Development of a Numerical Analysis Method for the Subcooling of Liquid Hydrogen Induced by Helium Injection

Toshiki Nara･Haruka Nikado･Gen Fujiura･Hideyoshi Takashima (AIS Hokkaido)･Masaharu Uchiumi (Muroran Institute of Technology)

Bubbles injected into a liquid cool the liquid by generating heat of vaporization at the interface of bubbles through diffusion. To increase the energy density of cryogenic fuels stored in tanks, this study aims to develop a subcooling technique for densifying cryogenic liquids based on this phenomenon. In this presentation, we report a numerical method developed to evaluate liquid cooling induced by such bubbles.

Development of a Cooling Water Module for BEVs Achieving Compact Size, Low Pressure Loss, and Adoption of Recycled Resin

Toshiya Kogiso･Shintaro Horisawa･Yasuhiko Esaki･Masao Kihara･Masato Ishii (Aisin)

To address the increasing demands for advanced thermal management in BEVs and improve vehicle packaging, a cooling water module integrating the EWP volute chamber and valve bore into a manifold was developed and mass-produced. By adopting a three-dimensional flow path, both compactness and low-pressure loss were achieved. In addition, recycled resin was applied to the manifold, and a structural design ensuring long-term reliability under high-temperature and high-pressure conditions was realized for the integrated resin structure.

AI Surrogate Modeling of the Refrigeration Cycle for Improving Thermal Management System Development Efficiency

Takumi Uemura (Mazda)･Bisser Raytchev (Hiroshima University)･Kenta Kobayashi (Mazda)

In electric vehicle development, a thermal management system integrating the refrigeration cycle and the powertrain is being investigated to address battery degradation and related issues. The computationally intensive refrigeration-cycle CAE model was converted into an AI surrogate model, allowing high-speed simulation. In addition, a reliability assessment model was introduced to verify the validity of the AI model outputs. This report summarizes these technical efforts.

Development of an EV HVAC Power Consumption Prediction Model Based on Multivariate Analysis and Machine Learning of Probe Data

Koichi Hasegawa･Haruhisa Tsuchikawa･Hiroki Matsui･Haruki Fukui (Nissan Motor)

Our BEV's Intelligent Route Planner function is built upon vehicle energy consumption prediction. Among its components, HVAC power consumption varies considerably with environmental and operating conditions, making high-accuracy prediction a key challenge. This study extracts feature variables from vehicle probe data, constructs a machine learning-based prediction model, and verifies improved prediction accuracy through validation against real-world driving data.

Basic Study of an Onboard Thermoelectric Power Generation System Utilizing Solar Heat and Driving Wind

Masaya Shimoike (SUBARU)･Tsutomu Iwase･Toshihiko Kozai (Gunma University/SUBARU)

This study examines the feasibility of an automotive thermoelectric generation system that uses both solar heat and driving wind. A custom-built test apparatus was used to simulate an in-vehicle environment and measure the open-circuit voltage of test samples. The results confirmed that adding an air layer increases power generation and enables continued power output even after solar irradiation stops.

Lifecycle greenhouse gas emission assessment of EVs using lithium-ion capacitors for wireless charging while driving

Asahi Nakayama･Ryosuke Ota (Tokyo Metropolitan University)

Dynamic wireless power transfer charges the vehicle battery only over limited road sections, resulting in a heavy load on the onboard battery. Therefore, this study investigates a system that combines the battery with a lithium-ion capacitor, which is suitable for high-power input and output, to extend battery lifetime. The effect of this lifetime extension is converted into greenhouse gas emissions over the entire life cycle, and the resulting reduction effect is quantitatively evaluated.

Development of Integrated Technologies for Dynamic Wireless Power Transfer and Autonomous Drive

Osamu Shimizu･Kazuyoshi Hanabusa･Kan Yamazaki (The University of Tokyo)･Zhihong Wang･Yoshinori Hirooka･Shigeo Kishi (PUES)

With the growing popularity of electric vehicles (EVs), wireless power transfer during driving (DWPT) has garnered significant attention in recent years. Applying DWPT to autonomous vehicles realize vehicles capable of driving indefinitely without a driver. A key challenge in utilizing this technology is that lateral misalignment of the coils cannot be resolved even when using sensor fusion technologies—such as cameras, LiDAR, and GPS. Therefore, we propose a method that estimates lateral misalignment based on the DC current at the receiver and vehicle dynamics model, and performs steering correction on the autonomous driving system side.

Energy Management System Utilizing EVs and Shared Energy Storage System

Yuito Ohno (Nagoya University)･Shinkichi Inagaki (Nanzan University)･Tatsuya Suzuki (Nagoya University)

This study investigates an energy management system that coordinates electric vehicles (EVs) and a shared battery within a local community for the effective utilization of surplus photovoltaic generation. We construct an operation method for the system and evaluate it from various perspectives, thereby discussing its effectiveness and remaining challenges toward practical implementation.

Investigation of EMC Testing During Charging and Discharging for On-board Bidirectional Chargers

Akira Mori (Toyota Motor)

The adoption of electric vehicles equipped with bidirectional chargers is advancing to make more effective use of electrical energy. Bidirectional chargers have both charging and discharging modes, but performing the EMC tests required by UN R10 for both modes presents a challenge due to increased testing effort. Therefore, we examined whether comparing EMC test results between the two modes could demonstrate equivalence, allowing testing to be limited to the charging mode alone.

Feasibility of Mobile Containerized DC Microgrids

Takeshi Serizawa (Daihatsu Motor)･Nobuhiro Kobayashi (Maeda)･Shiyouji Takeda (Daihatsu Motor)

We developed a 50 kW-class DC microgrid by applying automotive inverter technology. The system integrates a compact PCS, a 172 kWh battery, and V2X within a 20-foot container, enabling mobility. Combined with BEVs, it realizes a transportable distributed energy infrastructure. Demonstrations are being conducted through collaboration between a construction company and an automotive manufacturer to validate power optimization and business continuity (BCP) benefits, and the effectiveness of this approach is discussed.

Development of an On-board Built-in V2X System Utilizing the MG Neutral Point

Takeshi Serizawa (Daihatsu Motor)･Kazuyuki Yoda･Satoru Fujita (Fuji Electric)･Shiyouji Takeda (Daihatsu Motor)

An on-board built-in V2X system can be realized by combining the neutral point of the motor generator (MG) with the main inverter. This study verifies its effectiveness using a proof-of-concept prototype equivalent to the actual system. Conventional BEV-based power infrastructure requires expensive dedicated V2X equipment. In contrast, the proposed approach enables V2X functionality with minor modifications to existing systems, significantly reducing cost and complexity. Experimental results confirm stable operation and feasibility. The proposed method eliminates additional power conversion hardware and is expected to accelerate the practical use of BEVs as distributed power infrastructure.

Examination of Requirements for Testing xEVs on a Chassis Dynamometer with the Road Load Equivalent to Actual Driving Conditions
-1st report: Problems in Chassis Dynamometer Testing Caused by Vehicle Losses in xEVs-

Hisakazu Suzuki (NALTEC)･Isamu Inoue (Ono Sokki)･Tomonobu Furuta (MEIDENSHA)･Yoku Hirose (HORIBA)･Noriaki Nakate (JATA)

In electric vehicles, the absence of a clutch and the motor rotating during coasting can lead to discontinuous changes in vehicle losses. However, this is currently addressed by using an approximate formula when setting the road load on the chassis dynamometer. This point requires improvement to achieve the goal of reproducing actual road driving on the chassis dynamometer, as outlined in the Chassis Dynamometer Testing Method Subcommittee. This report presents the current status and concerns regarding this issue.

An e-Axle Loss Evaluation Method Using Continuous Measurement, Assuming Machine-Learning-Based Data Analysis

Ryoya Kodama･Haruhisa Tsuchikawa･Hiroki Matsui･Takaya Inukai･Kazunao Takashima (Nissan Motor)

Measurement of e-Axle losses, a major loss contributor in electrified vehicles, depends under in-vehicle operating conditions not only on rotational speed and torque but also on oil temperature and voltage. Therefore, measurements across multidimensional conditions are required, resulting in long test durations. In this study, we designed a continuous measurement approach that enables wide variations in oil temperature and voltage over the operating region, and rapidly constructed an e-Axle loss map using machine learning based on the acquired data. The effectiveness of the proposed approach for loss evaluation was confirmed.

Energy Management Based on Driving Pattern Classification Using Clustering Methods

Yuto Ishibashi･Kazuki Hayashi･Makoto Kozuka･Yousuke Hirowatari (Nissan Motor)

Current energy management strategies for series HEVs rely on a comprehensive set of control parameters that take multiple driving patterns into account, leaving room for fuel-economy improvement through pattern-specific optimization. In this study, driving patterns are classified by clustering historical driving data, and pattern-optimized control is applied. The effectiveness of the proposed control is validated.

Development of On-board PV System Model Using Modelica Language and Its Application to xEV Model

Norifumi Mizushima･Hidenori Mizuno (AIST)

In preparation for the implementation of the off-cycle credit framework, it is essential to establish a quantitative evaluation methodology for assessing the fuel economy improvement achieved by energy-saving technologies whose effects are not adequately captured by conventional chassis dynamometer testing. In this study, an on-board photovoltaic power generation system was modeled using the Modelica language, and the developed model was subsequently integrated into a vehicle simulation model developed at AIST. By performing vehicle-level simulations, the impact of the photovoltaic system on fuel consumption was quantified, thereby allowing for a systematic evaluation of its contribution to real-world fuel economy improvement.

Real-World Driving Behavior Analysis and Speed Variation Pattern Optimization for Improving the Energy Efficiency of an Electric Garbage Truck
-A Study Focused on Door-to-Door Waste Collection Operations-

Yiyuan Fang･Jiakai Gao･Yida Bao･Wei-Hsiang Yang･Yushi Kamiya (Waseda University)

This study investigates the real-world driving behavior and energy consumption characteristics of an electric garbage truck during door-to-door garbage collection operations. Analysis of measured operational data revealed characteristics such as frequent stop-and-go driving, long idling periods, and limited opportunities for regenerative braking. Furthermore, speed change pattern optimization was conducted for representative driving trips under identical travel distance and average speed conditions. The results demonstrated that reductions in powertrain losses and driving resistance could improve electricity consumption by approximately 20–28% compared with actual driving operations. These findings confirm the effectiveness of eco-driving speed pattern optimization for electric garbage trucks.

Analysis of fuel efficiency improvement technologies for hybrid vehicles using real road driving

Akira Kato･Kosuke Numata･Riku Anjo (Teikyo University)

The electrification of automobiles is progressing toward achieving carbon neutrality (CN) by 2050. However, there are many challenges to the widespread adoption of battery electric vehicles (BEVs), and in Japan, the sales ratio of hybrid electric vehicles (HEVs) is high. In this study, we conducted road tests using a low-fuel-consumption compact HEV and analyzed the results in comparison with the previous year's HEV model to analyze technologies for improving HEV fuel efficiency using real-road driving.

Multi-Point Heat Flux Measurement and Evaluation of Abnormal Combustion Effects in Direct-Injection Hydrogen Motorcycle Engines

Shoki Mashiko･Masakuni Oikawa･Yuji Mihara･Yuki Kaga･Aoshi Yokomori (Tokyo City University)･Takumi Iwata (MOTORA)･Hiroshi Kato･Kyohei Izumi (Kawasaki Motors)･Kenichi Sano (Honda Motor)･Tomohiko Kamio (Yamaha Motor)

Four heat flux sensors were installed on the cylinder head of a direct-injection hydrogen motorcycle engine, and transient heat flux measurements were carried out over a wide engine speed range from 2000 to 10000 rpm. In addition, heat flux behavior under abnormal combustion conditions at high engine speeds was successfully captured. Based on multi-point simultaneous measurements, this study elucidates the heat flux characteristics at high engine speeds and evaluates the influence of abnormal combustion on wall heat load.

An Investigation of Abnormal Combustionj Induced by Abnormal Electrical Discharge in a Direct-Injection Hydrogen Engine for Motorcycles

Hiroshi Kato･Kyohei Izumi･Yoshinori Nakao･Yusaku Matsumoto･Satoaki Ichi (Kawasaki Motors)･Tomohiko Kamio (Yamaha Motor)･Yoshinari Ninomiya (Suzuki Motor)･Kenichi Sano･Yusuke Marui･Takashi Kondo (Honda Motor)

Abnormal combustion phenomena, such as pre-ignition and knocking, are critical issues in the development of hydrogen engines for achieving carbon neutrality. In this study, the occurrence of abnormal combustion caused by abnormal electrical discharge was investigated in a direct-injection hydrogen engine for motorcycles through in-cylinder visualization and measurements of the secondary ignition voltage.

Analysis of the Effect of Hydrocarbon-Hydrogen Mixture on Flame Propagation Characteristics Using In-Cylinder Visualization

Tomohiro Nakamura･Takuya Hotta･Ryosuke Suda･Takamori Ueno (Nihon University)･Yoshinori Nakao (Kawasaki Motors)･Koichiro Matsushita (Honda Motor)･Tomohiko Kamio (Yamaha Motor)･Yoshinari Ninomiya (Suzuki Motor)･Akira Iijima (Nihon University)

In this study, we investigated the effect of hydrogen-hydrocarbon mixtures on combustion characteristics using in-cylinder visualization experiments and pressure analysis. The flame behavior was recorded using a high-speed camera and analyzed. As a result, mixing hydrogen improved flame propagation speed. Additionally, ignition characteristics were enhanced, resulting in earlier heat release rates and more stable combustion.

Study on a Two-Stage Hydrogen Engine Employing Diluted Stoichiometric-Combustion with 100% EGR of Lean-Combustion Exhaust Gas

Dengpei Chen･Yasu Moriyoshi･Takeshi Ishida･Tatsuya Kuboyama (Chiba University)･Hideki Kato･Hideaki Osada･Tomoyuki Sato (Hino Motors)･Keiso Takeda (Enable)

To realize zero emissions, simultaneous reduction of CO2 and NOx emissions from internal combustion engines is required. In this study, a two-stage hydrogen engine system enabling the application of a TWC was proposed through simulations using diluted stoichiometric combustion with 100% EGR of lean-combustion exhaust gas. Based on the simulation results, a prototype engine based on a four-cylinder diesel engine was developed for further investigation.

Optimization of Combustion Chamber Geometry for Direct-Injection Hydrogen Engine Using Mixture Formation Analysis and Machine Learning

Kentaro Minoda (Tokyo City University)･Nobuhiro Shimmura (Tokyo City University/Kawasaki Heavy Industries)･Masakuni Oikawa･Shota Tsukamoto (Tokyo City University)･Sekai Miyamoto (Kawasaki Heavy Industries)･Yuji Mihara･Yasuo Takagi (Tokyo City University)

To achieve high thermal efficiency and low emissions in hydrogen engines, optimization of mixture formation, including combustion chamber geometry, is essential. In this study, three indices, including mixture homogeneity, were defined to evaluate mixture formation, and combustion chamber geometry was optimized by quantitatively assessing these indices using machine learning. Furthermore, the validity of the proposed approach was experimentally validated.

Study of jet behavior and mixture formation processes in hydrogen engines

Ken Ayukawa･Akichika Yamaguchi･Seiya Nishimura･Satoru Sasaki･Masanori Goto･Kazufumi Serizawa (DENSO)

Hydrogen engines are a promising option for achieving carbon neutrality, but improving the homogeneity of the air-fuel mixture is a challenge in achieving both abnormal combustion avoidance and high power/low NOx emissions. In this study, we focused on the air-fuel mixture formation mechanism within the engine cylinder and clarified the injection and jet requirements necessary for homogeneous mixture formation through CFD analysis and engine test.

Study on Screening Method for Catalysts Using Arc-Plasma Deposition (Part 2)
-Exploration of NH₃ Selective Oxidation Catalysts-

Teppei Ohori･Kasumi Yonemama (Isuzu Advanced Engineering Center)･Masato Machida (Kumamoto University)･Hisashi Ozawa (Isuzu Advanced Engineering Center)

Candidate materials for NH₃ selective oxidation (NH₃-SCO) catalysts were explored using a catalyst screening method based on arc plasma deposition. The obtained findings were applied to ammonia slip catalysts used in diesel engine aftertreatment systems, resulting in excellent catalytic performance characterized by high ammonia oxidation activity and low formation of NOx and N₂O byproducts.

Analysis of White Solids Derived from Urea Solution in a Urea SCR System

Kozue Sato･Hayato Kojima (Waseda University)･Junji Sakai (Isuzu Motors)･Jin Kusaka (Waseda University)

In urea SCR systems, deposits believed to originate from urea and its polymerization products form inside the exhaust pipe at low temperatures. In this study, deposits were collected at various low exhaust temperatures, and their compositions were estimated through thermochemical analysis. Furthermore, assuming that the decomposition process of the deposits upon heating consists of three-step first-order reactions, the collision frequency factors and activation energies for each reaction were experimentally determined.

A Study on Changes in NOx Conversion Performance of Urea SCR Catalysts Due to Urea Pulse Injection

Yujin Ueki･Fuka Yoshida･Jin Kusaka (Waseda University)

There is a growing need to reduce NOx emissions from diesel vehicles. In this study, the NOx conversion performance of a urea SCR catalyst was investigated by comparing steady urea injection at 1 Hz intervals with pulse injection, in which the presence or absence of urea injection was controlled at an arbitrary duty cycle. A computational model was developed to investigate the effect of urea injection methods on NOx conversion performance.

Hydrothermal aging mechanism on Cu-CHA type SCR catalysts assumed for use in H2-engines

Fumika Ono･Fuka Yoshida (Waseda University)･Takayuki Mori･Hiroya Yamada (Tokyo Roki)･Jin Kusaka (Waseda University)

With the global shift toward carbon neutrality, H2-engines are drawing substantial interest. For the aftertreatment of H2-engines, SCR systems are typically adopted for NOx purification. This study investigated the effects of hydrothermal aging and the water content in exhaust gas on multiple sorts of Cu-CHA type SCR catalysts through both experiments and numerical simulations.

Development of Real-World Emission Reduction Technologies
-(Part 3) Study on Emission Reduction by Vehicle Control Using V2X Information-

Mie Kato･Masato Ikemoto･Takahiro Tsukagoshi･Hiromasa Nishioka･Bungo Kawaguchi (Toyota Motor)

Under real-world conditions, traffic flow constantly changes, affecting engine operation and catalyst states through driver behavior, and consequently altering emission characteristics. Therefore, further reduction of real-world emissions is expected by proper coordination between traffic and vehicles. In this study, traffic information simulating V2X was reproduced in a previously developed digital twin environment, and the effectiveness of traffic–vehicle coordination in reducing emissions is demonstrated.

Development of Real-World-Emission Reduction Technologies (Fourth Report)
-Study on Emission Reduction through Driver Behavior Modification-

Masato Ikemoto･Kohei Imai･Keita Moriyama･Takahiro Tsukagoshi･Hiromasa Nishioka･Bungo Kawaguchi (Toyota Motor)･Yutaka Arakawa (Kyushu University)

Achieving real-world zero emissions requires an integrated approach encompassing powertrains, driver behavior, and traffic flow. This study investigates emission reduction through driver behavior modification using a digital twin environment. Emissions induced by driver operations were predicted in advance, and behavioral interventions were applied to drivers. The results demonstrate a measurable shift in environmental awareness and a statistically significant reduction in NOx emissions, highlighting the effectiveness of targeted driver interventions for promoting environmentally conscious driving in real-world conditions.

Improvement of HC and NOx conversion rate by detecting the oxygen amount in the catalyst at restart of 100% Electric Drive HEV

Kouichi Murakami･Atsushi Morohoshi･Tomohiro Sakata (Nissan Motor)

Reduction of exhaust gas in engine restart of 100% Electric Drive HEV was examined. Focusing on the control of the amount of oxygen absorbed by each catalyst in the multi-stage three-way catalyst system, oxygen sensors were placed between the catalysts to optimize the target air-fuel ratio. As a result, the HC and NOx conversion rates were greatly improved by the rapid consumption of oxygen in the front-stage catalyst and the retention of oxygen in the post-stage catalyst.

Air Qualities in 2050, What it is like, carbon neutral society?
-Impact Analysis of Automobile Tailpipe and Non-Tailpipe Emissions-

Yusuke Yasukawa･Hiroyuki Yamada (Tokyo Denki University)･Yoshiaki Yamadaya (Ibaraki University)･Tazuko Morikawa･Masamitsu Hayasaki (JARI)･Hiroe Watanabe (Nissan Motor)･Kotaro Tanaka (Ibaaraki University)･Shinichiro Okayama (Motolity)･Yoshiaki Shibata (Institute of Integrated Atmospheric Environment)･Toru Kidokoro (Toyota Motor)

We conducted air quality simulations for the year 2050 to achieve carbon neutrality in accordance with the 7th Basic Energy Plan. Furthermore, to demonstrate the effectiveness of automotive environmental measures based on these results, we performed sensitivity analyses for tailpipe emissions, non-tailpipe emissions, and both combined.

Analysis of CO2 Emissions and Cost-Effectiveness in Long-Term Scenarios for the Automotive Sector

Shuichi Kanari･Hiroshi Hirai･Takaaki Kitamura (JARI)

The authors developed a long-term CO2 emissions model for the automotive sector to analyze scenarios up to 2050. Previously, the cost analysis focused only on vehicle-specific measures, such as engine efficiency and vehicle prices. This study newly incorporates costs for traffic flow management and optimized vehicle utilization. This enables the calculation of integrated costs in the automotive sector. Finally, CO2 reduction costs were evaluated based on the Strategic Energy Plan.

Effect of Fabrication Parameters on CO Oxidation Characteristics of Three-Way Catalyst Microparticles Membrane on Gasoline Particulate Filter

Eugene Gatete･Tsuyoshi Nagasawa (Institute of Science Tokyo)

This paper investigate effect of membrane fabrication parameters on CO oxidation for advanced gasoline particulate filters with three ways catalytic TWCGPF functionality. Using ultrasonic spray, TWC microparticles were generated at 700 and deposited onto GPF wall. CO oxidation were conducted to investigate catalytic performance of metal amounts and sintering temperatures. Comparing both two and four times precious metal loadings over standard TWC/GPF fired at 900, the light-off temperature T50 decreased the catalyst performance by 4.196 and 9.091 percent, however it led to an increase of CO conversion rate at full conversion temperature T100 by 33.984 and 32. 031 percent respectively

Emission Characteristics and Evaluation Method of Solid Particle Number from Diesel Engines Equipped with a Periodically Regenerating DPF

Ayumi Shimura (NALTEC)

In periodically regenerating DPFs, changes in filtration efficiency cause significant variations in SPN emissions. Immediately after regeneration, reduced filtration efficiency results in increased SPN emissions and variability. This study evaluates SPN emission characteristics in heavy duty diesel engines equipped with a periodically regenerating DPF and proposes a simple and appropriate evaluation method for SPN emissions during certification testing.

A Study on Changes in Exhaust Gas Performance During the Use Process of Heavy-Duty Trucks Equipped with Urea SCR System

Toshiro Yamamoto (NALTEC)

For heavy-duty truck equipped with urea SCR systems, we conducted periodic chassis dynamometer tests as their accumulated mileage increased from 150,000 km to 500,000 km, and continuously collected emissions data from the same vehicle. Based on this, we analyzed changes in exhaust gas performance by examining emissions of NOx, PM, N₂O, and other pollutants during the use process, and investigated the causes of these changes. Analysis revealed that as the accumulated mileage increased, the SCR catalyst temperature decreased to approximately 25°C to 30°C. It was considered possible that this caused changes in NOx, PM, and N₂O emissions.

Feasibility Study of Applying a Honeycomb Structure for Direct Air Capture on Vehicles

Ryosuke Sakuma･Kota Kaneyama･Kazuto Miura･Hideyuki Toyoshima･Tetsuo Toyoshima (NGK)

To evaluate the feasibility of applying a honeycomb structure for direct air capture (DAC) on vehicles, airflow during vehicle operation was simulated and CO₂ adsorption behavior was examined. Based on the relationship between airflow and adsorption kinetics obtained, the appropriate structure volume and replacement frequency were assessed.

Variable compression ratio system using a free piston
-A new mechanism that enables the Atkinson cycle-

Tomoaki Sato (Kanagawa Institute of Technology)･Tatsuro Kitahara (Shonan Institute of Technology)

This study proposes a novel internal combustion engine system that enables variable compression ratios even during engine operation by employing a free piston installed inside the cylinder. The proposed system realizes the Atkinson cycle without requiring a complex mechanical structure, enables optimal control according to operating conditions, and demonstrates the potential for creating a new thermodynamic cycle.

Research on a Small Two-Stroke Uniflow-Scavenged Opposed-Piston Engine

Ryoma Otsuki･Kai Araoka･Takumi Okuyama･Ikumi Okawara･Yoshiaki Yamazaki･Akira Iijima (Nihon University)

In recent years, while the proliferation of electric vehicles (EVs) has advanced in tandem with decarbonization initiatives, internal combustion engines have garnered renewed attention due to lingering challenges such as driving range limitations and charging infrastructure deficits. Under these circumstances, there is a growing demand for high-efficiency engines that depart from conventional design paradigms. To address this need, this study focuses on power-generation engines and investigates a two-stroke opposed-piston engine.

Comparative Study of Measurement Methods for Engine Efficiency Benchmarking in Hybrid Vehicles

Sukjoo Kim･Youngkuk An･Byungsoon Min (Tenergy)

Engine efficiency is a critical factor in determining fuel economy performance of hybrid vehicles, making accurate benchmarking of competitor vehicles essential for guiding development decisions. Three evaluation methods were investigated: a simplified estimation approach using engine torque acquired via CAN communication, a calculation method based on fuel flow meter and combustion pressure data, and a direct measurement approach with a torque sensor installed between the engine and transmission while connected to the vehicle. The measurement accuracy and practical applicability of each method were evaluated through mutual comparison of the engine efficiency results obtained.

Environmental Impact Assessment of the Rebuilt Parts Manufacturing Process

Toya Hanaki･Tatsuki Yamada (Toyama Prefectural University)･Akihiro Hayakawa･Shundai Nezu･Mitsunobu Fujita (NGP)･Masato Inoue (Meiji University)･Takao Mori･Yamada Shuho (Toyama Prefectural University)

Conventional environmental impact assessments of recycled parts have primarily focused on greenhouse gas emissions related to climate change, often lacking a multifaceted analysis of broader environmental impacts. In this study, targeting automotive engines and auxiliary components, the environmental impacts associated with a series of processes ranging from end-of-life vehicle dismantling to remanufacturing were quantitatively evaluated using the LIME2 methodology. Through this comprehensive assessment, the specific environmental impact generated by each individual process was clarified, and the most effective target processes for environmental improvement were successfully identified.

Environmental Impact Assessment for the Remanufacturing of Automotive CVT

Naoki Ichizawa (Waseda University)･Shingo Kodama･Akiko Sawai (Aisin)･Hiroshi Narita (Awquis Japan)･Norihiro Itsubo (Waseda University)

To promote a circular economy, this study comprehensively evaluates the environmental benefits of remanufacturing automotive CVT. By executing life cycle assessments with empirical data gained from detailed process tracking on the manufacturing floor, the research demonstrates that component reuse successfully mitigates both midpoint and endpoint environmental burdens across multiple impact domains while significantly lowering integrated ecological damage costs. Establishing this rigorous quantitative framework through actual industrial practices bridges key information gaps in domestic recycling. Consequently, these findings provide a vital scientific foundation to advance industry standardization and foster the robust expansion of sustainable markets.

Structural Changes in Oligomers and Additives in Polypropylene during Mechanical Recycling

Hirotaka Shioji･Nobuko Taniguchi･Suguru Tamura･Toru Yamanaka (Toray Research Center)･Riku Hashimoto･Ryo Ikegami (Aisin)

Polypropylene (PP) is a major plastic used in automotive applications, and recycling of PP is important. Understanding how PP changes during recycling is also useful for distinguishing it from virgin materials. In this study, changes in PP during material recycling were examined, focusing on the behavior of oligomers, and additives.

Effect of Initial Black Mass Composition on Valuable Metal Recovery in Hydrometallurgical Recycling

Yasuhito Aoki･Hirofumi Moriwaki･Tomohiro Ito･Junpei Yahiro･Hironobu Tsuji (Toray Research Center)

With the increasing practical use of electric vehicles, recycling of lithium-ion batteries (LIBs) has become increasingly important. In this study, two types of black mass with different initial states were prepared and compared. The leaching behavior of Ni, Co, Mn, and Li in a hydrometallurgical process, as well as the composition of insoluble residues, were systematically analyzed. Based on these results, the impact of the initial black mass composition on the recovery efficiency of valuable metals in hydrometallurgical recycling is discussed.

Generalization of Truck Disassembly Process Models for Reused Parts Production and Environmental Impact Assessment

Aoba Nohmura･Kazumasa Kita (Toyama Prefectural University)･Akihiro Hayakawa･Shundai Nezu (NGP)･Yuichi Takenaka (Japan Truck Refine Parts Association)･Mitsunobu Fujita (NGP)･Masato Inoue (Meiji University)･Takao Mori･Shuho Yamada (Toyama Prefectural University)

In automotive recycling, truck disassembly processes vary by facility, and no standardized model exists. For this reason, the calculated environmental impact reductions from reused parts vary depending on the facility. In this study, truck disassembly process models from two different facilities are generalized, and their environmental impacts are presented.

Control Strategies for Extending the Service Life of Repurposed EV Battery Systems

Tenyu Yan･Rika Isawa･Hiroki Nagano (Mazda)･Junichi Ishimaru･Akihiro Ogawa (The Chugoku Electric Power)･Nobuhide Seo･Kazuhiro Murashige･Takashi Utsunomiya･Tomu Fujikawa･Nobutaka Wada (Hiroshima University)

Second-life utilization of automotive batteries is expected to reduce environmental impacts; however, in stationary second-life battery systems composed of multiple batteries, degradation variability causes the battery with the shortest lifetime to constrain overall system longevity. This study develops a power allocation control scheme based on model predictive control (MPC) incorporating degradation models. The proposed method satisfies external power demands while mitigating degradation imbalance and extending system service life. Its effectiveness is demonstrated through experimental validation and simulation.

Vehicle Dynamics Performance Prediction by Integrating a Driving Simulator and Brake HILS

Kota Akiyama･Ryosuke Ide･Yoshinori Maeda (Toyota Motor)･Kentaro Takechi･Miku Kawai (Toyota Technical Development)

This study proposes an integrated evaluation environment combining a driving simulator with a brake hardware-in-the-loop system to predict vehicle dynamics performance at an early development stage. As a case study, traction control performance was evaluated under split-μ road conditions. By incorporating real brake ECUs and actuators, realistic control behavior was reproduced. The results demonstrate that the proposed environment enables trade-off analysis between stability and acceleration performance, reducing reliance on vehicle testing.

Numerical simulation on the effect of body stiffness on vehicle dynamic behavior considering detailed tire model

Haruki Honda･Haruya Oshita･Kenji Yoshida (Hiroshima Institute of Technology)

In this study, numerical simulation on the effect of body stiffness on vehicle dynamic behavior considering a four-wheel model with a detailed tire model are carried out. The target vehicle is FSAE car in our university. Focusing on the transient behaviors in response to steering and braking inputs, this study clarifies the influence of body deformation on tire slip angle and load changes on vehicle dynamics, and quantitatively demonstrates the necessary and sufficient body stiffness.

Development of an Objective and Quantitative Evaluation Method for the Dynamic Support Performance of Seats During Driving

Hideaki Shibue (S&VL)

This study aims to establish a new method for objectively and quantitatively evaluating seat performance during driving. We constructed a framework that integrates measurements of the driver’s body movements, steering force, and grip force to quantify the dynamic support characteristics of the seat. Through driving simulator experiments, we identified differences in seat characteristics and demonstrated the effectiveness of this method.

Development of 3-wheel EV vehicle Durability Mode Through Local Measurement in India

Seungyong Bae･Daejin Kim･Seongwoo Kim･Miyong Lee･Seungwan Son･Donghyun Ha･Damhyun Kim･Gyunam Park･Jaewan Kwon･Junwoo Chung (Hyundai Motor)

The company is pursuing the development of a three-wheeled electric vehicle to enter the Indian market and has set securing durability performance as a key task. This study aims to improve vehicle design and verification efficiency by developing a TDP that reflects the driving conditions in India. It sets durability targets, sets road ratios, constructs routes, sensors, and measures. Accelerated durability testing scenarios were developed using competitor testing routes. Finally, three types of TDPs were constructed for the combined actual road, unpaved road, and Rig test conditions to establish a durability evaluation system.

A Control Method for Enhancing Vehicle Handling and Stability via Driving and Braking Force Distribution Based on Vehicle Sideslip Angular Velocity

Shoma Baba･Kaoru Sawase･Hiromitsu Toyota･Ryosuke Koga･Kazunori Kawai (Mitsubishi Motors)

Electric vehicles can achieve high handling performance owing to their high flexibility in longitudinal force control and fast response characteristics. However, rear-wheel instability may occur under low-friction or rough road conditions. To address this issue, a novel control law is introduced in addition to conventional yaw-rate feedback control, which constrains the vehicle sideslip angular velocity within a specified range. The proposed control method is demonstrated to improve both steering response and vehicle stability under low-friction road conditions.

Damping Ratio Control in the Linear Region of Vehicle Dynamics

Naoto Ohkubo･Ryo Koyama･Fumiaki Honjo (Honda R&D)

This study proposes a control method that enables arbitrary adjustment of the damping ratio by applying a direct yaw moment through longitudinal forces, without altering the steady-state gains of yaw rate and sideslip angle or the natural frequency. Furthermore, the effectiveness of the proposed method, which is designed to vary only the damping ratio, is verified through simulations.

Analysis of driving and dynamic characteristics of BEV trucks considering loading conditions

Kazumasa Takahashi･Takayoshi Kamada (Tokyo University of Agriculture and Technology)

This study investigated the dynamic characteristics of small BEV trucks to contribute to the development of safe and reliable vehicle control systems. Since truck behavior is expected to change depending on cargo loading conditions, five different loading conditions were considered in the analysis. Under each condition, the steering response characteristics of a conventional small internal combustion engine truck and a small BEV truck were compared. The results provide insight into how electrification and load distribution influence vehicle motion characteristics and handling performance, which are important factors in the design and evaluation of future vehicle control technologies for commercial trucks.

Development and Performance Evaluation of an MR Fluid Variable Damping Force Rotary Damper

Yukihiro Hanajima (THK)

In recent years, advances in vehicle motion control have increased the performance requirements for variable damping-force dampers. In this study, an MR fluid variable damping-force damper has been developed by combining a rotary damper with MR fluid and applying a magnetic field, achieving a wide range of damping-force control and compact size. In this report, the performance was evaluated through bench tests and vehicle tests.

Theoretical Analysis and Experimental Verification using Test Bench of Jacking Characteristics during Cornering

Masaki Yamamoto (Kanagawa Institute of Technology)･Motoshi Ohki (Toyota Motor)

Jacking characteristics during steady-state cornering are analyze theoretically, covering not only independent suspension systems but also rigid suspension systems, such as those using torsion beam type. Furthermore, the experimental method using a test bench that is unaffected by road surface inputs to verify the relationship between suspension type and jacking characteristics.

Development of an Edge Device and Cloud Environment for Replica Vehicle Implementation

Seungwan Son･Daejin Kim･Seungyong Bae (Hyundai Motor)･Minchul Lee (ACEWORKS)

To support the establishment of vehicle durability targets using data from a large fleet, an AI-based virtual sensor was developed to enable the creation of a replica vehicle. An Edge Device was implemented to provide an onboard development environment, built on the ROS framework, enabling machine learning model development using CAN RAW data and measurement data. These models facilitated the estimation of suspension transfer loads. Furthermore, a cloud-based development environment was constructed to support scalable data acquisition, model training, and load prediction, contributing to reliable and data-driven durability evaluation.

Path following Control for a Large Bus Based on a Vehicle dynamics Model Considering Road Curvature and Cant

Tomoki Arita･Ryosuke Sakurai･Toshiyuki Sugimachi･Toshiaki Sakurai･Shuichi Yahagi (Tokyo City University)･Fujio Momiyama･Keiji Aoki (ASMobi)

In steering control for buses, it is important to design a control system that considers vehicle characteristics. In this study, a vehicle dynamics model of a large bus considering road curvature and cant was constructed, and a model-based Path Following control system was designed. Furthermore, simulations with crosswind disturbances were conducted to evaluate the control performance of the proposed control system and its robustness under crosswind conditions.

Modal Analysis of a Simplified Motorcycle Model During Turning Motion

Junji Hirasawa (Ibaraki KOSEN (College of Technology))

This study aims to establish a novel and simplified motorcycle model. Since the Sharp motorcycle 4DOF model, which assumes straight running near the upright position, has limitations in analyzing turning motion, a novel model is developed based on a motorcycle turning with a reference roll angle, and modal analysis is conducted.

Study of Pinion Gear Support Structure of Electric Power Steering System

Takashi Miyoshi (Honda R&D)

This study investigated the mechanical performance required for the pinion gear support structure, including the torsion bar, in an EPS (Electric Power Steering) system to achieve a direct steering feel. The results clearly showed that the linearity of the side force and displacement acting on the pinion gear contributes to the direct steering feel. Therefore, we propose a new structure that can contribute to enhancing steering feel.

Effects of Equivalent Steering Torque Characteristics Derived from the Coupling Structure of Steering System and Vehicle Dynamic Characteristics on Handling Quality Evaluation

Jun Ishio (Honda R&D)･Masato Abe･Ikuo Kushiro･Masaki Yamamoto･Reon Suzuki･Makoto Yamakado (Kanagawa Institute of Technology)

A coupled formulation of the steering system with assist control and vehicle dynamic characteristics is presented, and it is shown that the steering system can be reduced from two to one degree of freedom via internal forces, even in the presence of nonlinear EPS assist control. The effects of the derived equivalent steering torque characteristics on driver handling quality evaluation are confirmed with driving simulator.

Proposal of Parametric Road Feel Reproduction Based on Phase Coupling in Tire-Order Vibration Sidebands

Takuya Suzuki (Honda R&D)

To reproduce road feel in steer-by-wire vehicles, phase difference analysis was applied to steering vibration during driving. The sidebands of tire rotational order vibration were found to be phase-coupled to the carrier at 180°, indicating they represent amplitude modulation in the FFT domain. A parametric excitation model preserving this coupling structure was proposed, demonstrating improved signal reproducibility compared to conventional methods.

Development of Steering Control for Steer-by-Wire Systems Using a Hierarchical Gradient Method
-(Part 1)-

Rei Fukai･Takashi Furuichi･Atsushi Tsubouchi (Honda R&D)･Hideaki Shibue･Hideyuki Muramatsu (S&VL)･Makoto Iwamura (Fukuoka University)

This study develops a steering control method aimed at improving the cornering stability of vehicles equipped with steer-by-wire systems. By employing a hierarchical gradient method, which enables stable optimization under multiple constraints, the steering angle is derived to enhance cornering stability. This paper presents the application method of the hierarchical gradient approach to steering control and reports the initial evaluation results obtained using a driving simulator.

Study on Predictive Haptic Guidance Using Phase-Lead Compensation in Urgent Takeover of Automated Driving

Kansei Hattori･Toshio Ota (Hiroshima Institute of Technology)

In the urgent transition of control from automated driving systems to drivers, steering delays caused by cognitive lag present a critical challenge. This study proposes a system that performs predictive steering operations through phase-lead compensation and generates corresponding steering haptic feedback. Furthermore, this study investigates the effects of this predictive haptic guidance on the cognitive delays of drivers.

Ground Layout Design Considering Voltage Drop in Multiple Electronic Components

Yoshiko Seino･Masashi Komada･Takayoshi Shigihara (Toyota Motor)

The stable operation of multiple electronic components related to vehicle handling stability requires a ground layout that reduces voltage drop. In this study, resistance calculations are performed using a full-vehicle body shell model, and a method for designing ground layouts that reduces variations in inter-ground potential differences and voltage drops under combined current input conditions at multiple grounding points is presented.

Vehicle Lateral Control Based on Data-Driven ADRC

Shuichi Yahagi (Tokyo City University)･Itsuro Kajiwara (Hokkaido University)

This work introduces a data-driven design of the active disturbance rejection control (ADRC) for vehicle lateral control. This control method is effective for industrial systems with nonlinear and/or time-varying characteristics. However, its performance heavily depends on the choice of design parameters. The proposed method incorporates a one-shot data-driven design approach to optimize ADRC parameters directly from a set of data without repeated experiments. The effectiveness of the proposed method is demonstrated using a vehicle simulator, and the results confirm that it achieves good tracking performance.

Crowdsourced Generation of Parking Maps Using Mass-Production Vehicle Data for Parking-to-Parking Automated Driving

Yudai Kato･Kazutaka Hayakawa･Hiroshi Okabe (Aisin)･Keisuke Maekawa･Iori Nagase (Panasonic Advanced Technology Development)

Parking to Parking (P2P), which enables automated driving from an origin parking space to a destination parking space including both public roads and parking environments, is an important capability for next-generation mobility systems. To realize P2P, this study proposes a crowdsourced mapping technique for parking environments using sensor data collected from mass-production vehicles. Even under GNSS-denied conditions such as indoor and underground environments, the proposed method integrates observations from multiple vehicles to generate maps enriched with both geometric and semantic information. Furthermore, the approach enables continuous map updates without relying on dedicated mapping vehicles. The proposed framework aims to achieve a low-cost and scalable mapping solution, and its system architecture and effectiveness are investigated.

Development of Cloud-Based Parking Map Generation Technology for Automated Valet Parking

Morihiko Sakano･Takahiro Sakai (Hitachi)･Yoshinobu Ogasawara･Hidehiro Toyoda (Astemo)

This paper presents a cloud-based parking map generation and high-speed localization technology for Automated Valet Parking (AVP). A dual-descriptor map is introduced, which combines deep learning-based features for high-precision map construction with handcrafted features for real-time localization on edge devices. In addition, a divide-and-conquer map generation approach is proposed to significantly reduce processing time for large-scale parking environments. Experimental results using real-world data demonstrate that the proposed system achieves sub-meter localization accuracy with processing times suitable for real-time AVP applications, confirming its practical applicability.

Development of a Shape Optimization Framework Using AI-Based Shape Generation for Electric Water Pump Design and Its Practical Implementation Challenges

Yuka Ibaraki (Aisin)･Toshiki Terabe (Toyota Motor)･Kyohei Kitamura･Shohei Nakai (Aisin)

A shape optimization method combining DeepSDF-based shape generation and surrogate modeling was investigated for an electric water pump. By leveraging the relationship between latent variables and performance, optimization and performance prediction of newly generated shapes were achieved. This report discusses the challenges identified during practical application, along with approaches to addressing these issues and future perspectives for improving the applicability of the method.

Study on Performance-Driven 3D Shape Generation Using Latent Space

Keisuke Ootake･Hiroaki Suzuki･Yusuke Hasaba (Yamaha Motor Engineering)･Kiyofumi Shijo･Hibbanurrohim Ibram Muhammad (Astraea Software)

This study proposes a method for 3D shape generation and design support using latent space. A hybrid generative model combining a variational autoencoder (VAE) and a diffusion model is developed. By mapping CAE analysis results of the generated 3D shapes onto the latent space, the method enables inverse exploration of shapes based on target performance and demonstrates the potential for novel shape generation. The effectiveness of the proposed approach as a design support method is also confirmed.

Analysis of Large-Scale Real-World Driving Data for Prediction of Vehicle Dynamics on Arbitrary Driving Routes

Masanori Okamoto (Toyota Systems)･Hideaki Bunazawa･Tomohiro Yoshimura (Toyota Motor)･Thomas Bernes Lasserre (Toyota Motor Europe)･Shigeki Hasegawa (Toyota Motor)

Using large-scale real-world driving data collected from connected vehicles, the effects of vehicle type, region, and road conditions on vehicle dynamic characteristics (e.g., vehicle speed and acceleration) were analyzed. The obtained characteristics are expected to enable highly accurate prediction of driving behavior along arbitrary driving routes and to be applied to simulations of power performance, fuel economy, and durability.

Machine-Learning-Based Quantification of Subjective Evaluation for Vehicle Cornering Behavior

Ryoya Kanahori･Tomohiro Shimizu･Satoru Sugiyama･Makoto Okamoto･Takafumi Asano･Takashi Kaneko (SUBARU)

The assessment of vehicle dynamic performance has conventionally relied upon subjective evaluation by expert drivers, and translating such qualitative judgments into quantitative inputs for vehicle design and control has required substantial engineering effort. In this study, we developed an automated analysis framework that combines a Random Forest model with similarity assessment in the feature space, using measured driving data and subjective rating scores. The proposed approach enables rapid and reproducible derivation of performance indices that correspond to highly rated vehicle behavior, thereby establishing a foundational technology for improving the efficiency of vehicle dynamics design.

AI Image Generation for Safety Evaluation of Automated Driving Systems

Nobutoshi Ozaki･Tetsuya Niikuni (NALTEC)

Evaluating the safety of automated driving systems requires verifying whether such systems accurately recognize various situations in traffic. Datasets consisting of only real-world images require extensive driving data collection to capture rare situations, such as edge cases. In this study, we focus on object detection AI for traffic images and investigate a method for generating synthetic test images using generative AI.

Automation of test scheduling using mathematical optimization

Toshihiro Watanabe･Hiroshi Yoshimoto･Toshiki Terabe･Yuya Osamura･Junichi Abe (Toyota Motor)･Kosuke Suzuki･Tetsuro Sakamoto･Tomoko Ikuta (Fixstars)

To address the reliance on the experience and know-how of seasoned veterans for test planning, we introduced mathematical optimization to enable anyone to quickly create optimal test plans. By identifying the necessary equipment and personnel information for testing and formulating the tacit knowledge and rules of seasoned veterans into mathematical equations, we were able to not only create plans quickly but also analyze bottlenecks in test execution.

Consistency Evaluation System for ADAS ECU and Meter Display

Hiroyuki Takano (Nissan Motor)･Anhtuan Ngo･Ducphong Nguyen (Nissan Automotive Technology Viet Nam)･Tomohiro Kida (Fudo Giken Industry)･Daisuke Maruta (Accenture Japan)･Shigenori Tsunekado (Nissan Motor)

We developed an HIL system that automatically evaluates the consistency between ADAS ECU signals and meter displays. Icon images captured by a camera are recognized through image recognition and compared/judged in synchronization with the ECU signals. By converting the diverse and complex meter displays into signals and synchronizing them with the ECU signals for comparison, the evaluation process was simplified. This system was introduced into the vehicle verification process, where it was evaluated and contributed to reducing test man-hours.

A Method for Time Error Correction in SIL Simulation

Kyungnam Kim･Seungkyu Yoo･Hyunrak Ko･Sumin Park (Hyundai Autoever)

Precise time synchronization is crucial in Software-in-the-Loop (SIL) simulations. Conventional Sleep () functions lack microsecond accuracy, while Spinlock causes severe CPU degradation. This study proposes a hybrid time-delay method achieving 1-microsecond precision while maximizing CPU efficiency. It dynamically combines a low-cost timer (Sleep) with a high-cost timer (Spinlock). Using Welford's online algorithm, the system calculates the Sleep timer's statistical execution error in real-time. To save resources, it utilizes Sleep initially, transitioning to Spinlock only when the remaining wait time falls below the predicted error, effectively eliminating time discrepancies.

Research on Interface Methods between Virtual IP Models and Simulators in SIL Environments

Jaekyung Kim･Kyungnam Kim･Subin Jung･Haram Park (Hyundai Autoever)

In SIL environments, integrating virtual IP models with simulators using FMU standard causes performance degradation. This paper proposes direct interface approaches without FMU wrapper, defining optimized interfaces for data exchange and time synchronization. Experiments demonstrate reduced latency and increased throughput compared to conventional FMU-based approaches.

Development of a Parallel Level 4 Virtual Electronic Controller Unit Verification Platform Based on Cloud Infrastructure

Daeki Kim･YoungMo Lee (Hyundai Autoever)･HanSeung Myoung (Hyundai Motor)･Sunghoon Woo (Hyundai Autoever)

Conventional on-premises Level 4 virtual ECU verification has bottlenecks due to limited computing resources. This research proposes a parallel verification platform using cloud infrastructure. The platform executes multiple virtual ECU instances simultaneously in a distributed computing environment and processes verification in parallel according to software requirements. This reduces verification execution time and enables collaborative verification across multiple countries and departments. The results are expected to improve verification efficiency in automotive software development and shorten the development, verification, and deployment cycle.

Intelligent Fault Injection Scenario Generation Using Level 4 Virtual Electronic Controller Unit and Verification Efficiency Enhancement

YoungMo Lee･Daeki Kim･SungHoon Woo (Hyundai Autoever)

Manual fault injection scenario in Level 4 virtual ECU verification causes omission, redundancy, and inefficient resource allocation. This research proposes a methodology to automatically generate fault injection scenarios from functional safety requirements using AI. The methodology analyzes ISO 26262 requirements through machine learning and generates scenarios to enhance verification coverage. A priority determination algorithm eliminates redundancy and optimizes verification sequence, reducing verification time while expanding coverage. The results are expected to automate functional safety-oriented Basic Software verification, improve development processes, and reduce human errors.

Development of a TC39x TriCore Instruction Set Simulator for AUTOSAR OS QTDD ELF Verification Using AI-Assisted Methodology

Sunghoon Woo･Daeki Kim･Youngmo Lee･Kyungnam Kim･Jaekyung Kim (Hyundai Autoever)

This paper investigates whether AUTOSAR OS test ELFs can be executed on a SystemC ISS for the Infineon TC39x using AI-Assisted Methodology. The ISS implements six TriCore v1.6.2P cores with CSA chain, trap/interrupt handling, and 30 peripheral stubs (STM, MPU, MULTICAN, CAN-XL, GETH, FlexRay, ASCLIN etc). Completeness was improved via AI-driven datasheet analysis, MCAL sample code-based hardware modeling, and AI-assisted AUTOSAR OS boot register implementation. Key challenges -CSA linked-list reconstruction and 2-/6-core boot synchronization- were resolved under human knowhow.

Study on a Predictive Battery Charging Control System for Series Hybrid Electric Vehicles Using Gradient Information

Yuhi Abe･Takahiro Shimizu･Hyuga Cyujo･Mai Shinkawa･Jin Kusaka (Waseda University)

This study proposes a predictive battery charging control system for series hybrid electric vehicles using only road gradient information. The system actively uses battery energy during uphill driving to maximize regenerative energy recovery during subsequent downhill driving. A simulation model identified from real-world driving data was used for evaluation on a suburban route with large elevation changes. The results confirmed a significant increase in regenerated energy and an improvement in fuel efficiency, demonstrating the effectiveness of gradient-based predictive control without requiring uncertain velocity predictions.

Efficient Kalman Filter-Based Battery Pack SOC Estimation Using Bar Delta Filtering

Seyedmehdi Hosseininasab･Changwei Lin･Lennart Bauer (FEV Europe)･Tsuyoshi Horiba･Yasutaka Ikawa (FEV Japan)

Accurate estimation of SOC in lithium-ion battery packs is essential for safe reliable and optimized BMS in electric vehicles and energy storage. This study presents an efficient framework combining a lightweight Kalman filter with the Bar-Delta method for series-connected LFP cells. A simulation model with realistic cell-to-cell variations evaluates performance. The method estimates pack average SOC and cell deviations with lower computational cost. Results show comparable accuracy to full Kalman filtering while significantly reducing computation, enabling real-time embedded applications. It is suitable for resource-constrained hardware and scalable pack monitoring deployments today.

Comparison of IR, EKF, and NARX Estimators for Battery SOC and Voltage Prediction Across EV Pack Sizes

Alessandro Massimo Bertucci･Xinwei Li･Ratnak Sok (Waseda University)･Keiki Tanabe･Goro Iijima (Mitsubishi Fuso Truck and Bus)･Jin Kusaka (Waseda University)

This study compares Internal Resistance (IR), Extended Kalman Filter (EKF), and Nonlinear Autoregressive with Exogenous Inputs (NARX) estimators for battery state-of-charge and terminal-voltage prediction across S, M, and L electric-vehicle battery pack configurations. On regular-temperature JE05 measured logger data, IR and EKF achieved similar SOC accuracy but poor voltage reproduction, especially for the L configuration. NARX achieved higher joint SOC and voltage accuracy on the same data. Cold-chamber NARX results were separated by driving cycle, showing strong performance for 50 km/h and 80 km/h cases, while JE05 at -25 degC remained the most difficult voltage condition.

Battery Load Prediction in Market Environments Using Big Data and Generative AI

Yuya Hato (Mazda)

When lithium-ion batteries are used in electric vehicles, it is necessary to ensure reliability against degradation and thermal runaway, considering real-world customer usage patterns. Therefore, by applying generative AI to market big data, we developed a method to generate driving scenarios that replicate customer usage characteristics. We then developed a method to evaluate battery load intensity under market conditions by combining the generated scenarios with a one-dimensional model.

Measurement-Based Development of High-Fidelity Electrochemical Models for LFP Cells

Takatoshi Hasegawa･Ryotaro Miyazaki･Kazunao Takahashi･Kengo Araki･Tomomi Ejima (IDAJ)･Hironobu Tsuji･Hirofumi Moriwaki (Toray Research Center)

In battery-powered product development, electrochemical models are increasingly used, but methods for obtaining required parameters are not yet well established, and electrochemical parameters are often treated as tuning terms. In this work, we constructed a detailed measurement-based electrochemical model and demonstrate its value and importance.

Environmental Footprint of Aluminum and Steel BEV Battery Pack Structures under Equivalent Crash Performance

Shun Takenaka･Shuki Nakamura･Shota Chinzei (Kobe Steel)･Hatsumi Yoshino (Kobelco Business Partners)･Kazuyuki Hamada･Kenichi Watanabe･Masatoshi Yoshida (Kobe Steel)

Driven by increasing demand for environmental impact reduction, battery packs are required to simultaneously ensure crash safety and minimize environmental burdens. In this study, battery pack structures made of aluminum alloy and steel were designed to achieve equivalent crash performance under identical vehicle conditions, and their weight and environmental impacts over the life cycle were quantitatively evaluated.

Study on Improving Cycle Durability of Anode-free All-solid-state Batteries
-(Second Report)-

Takashi Nakagawa･Kyohei Izumi･Shuntaro Ujiie･Hayate Kusushita･Kenta Nagamine (Honda R&D)

Degradation analysis of anode-free all solid-state batteries and improvement of charge-discharge cycle durability by improving the specification of anode current collection foil will be reported.

Experimental Evaluation of Thermal Runaway and Thermal Propagation Behavior in Lithium-Plated Cells Using Laser Irradiation

Kenichiroh Koshika (NALTEC)･Hideki Tsuruga (JET)･Tomokazu Morita (Toshiba)･Keizoh Honda (JET)

This study evaluates the thermal runaway and thermal propagation behavior of lithium-plated cells using a laser irradiation method. Single-cell tests were conducted to compare the onset characteristics of thermal runaway, while propagation tests were performed using configurations of adjacent cells. The results demonstrate that lithium plating promotes the initiation of thermal runaway and significantly enhances the likelihood of thermal propagation between cells, indicating a reduction in battery safety associated with lithium plating.

SOH and Cell Balance Estimation Using Non-Destructive Diagnostics During Cycle Aging of a Battery Pack Emulating Repurposed Use

Tomokazu Morita (Toshiba)･Kenichiroh Koshika (NALTEC)･Hideki Tsuruga･Keizoh Honda (JET)

A battery pack emulating a repurposed battery, composed of cells with different degradation histories, was fabricated, and cycle degradation tests were conducted. As a non-destructive diagnostic method to estimate the state of health (SOH) and cell balance of the battery pack and each cell, the degradation state of the battery pack was estimated using charging curve analysis and estimation methods based on cell OCV-SOC. The estimation accuracy was evaluated by comparing the estimation results with the measured capacity of the battery pack.

Durability Prediction of Fuel Cell Adhesive Sheet by FC System Simulator

Ichikawa Ryosuke･Naoki Ogiwara･Norishige Konno (Toyota Motor)･Kyohei Kobayashi･Shigeyuki Watanabe (Toyobo)

The widespread adoption of fuel cells (FCs) has increased expectations for the commercial multi-purpose applications. For the heavy-duty mobility applications, increasingly severe durability requirements caused by longer operation times and higher temperatures necessitate the advanced durability design. In this study, we focus on an adhesive sheet providing the sealing and insulation functions in the FC cells. The durability prediction methodology is established by integrating the stress and strength concepts into an FC system simulator capable of analyzing the dynamically varying power generation distributions within the FC cell during the HDV driving.

ECMS-based Energy Management Strategy for a Hydrogen Fuel Cell Hybrid Yard Tractor

Juhan Lee･Beomho Lee･Taeho Park･Dohyun Park･Janghyeok Won･Deokjin Kim (Korea Automotive Technology Institute)

Hydrogen fuel cell (FC) hybrid powertrains are a zero-emission option for port yard tractors (YTs), whose high peak power, low average power, and frequent start-stop operation challenge battery-electric solutions. A software-in-the-loop (SILS) model of an FC hybrid YT-80 kW FC stack, 90.7 kWh battery, 310 kW motor-is built in MATLAB/Simulink with IPG TruckMaker. A representative duty cycle from 191 in-service trips shows 22 kW average and 232 kW peak power. The baseline rule-based supervisor yields bimodal FC operation, motivating a proposed ECMS with a PI-based adaptive equivalence factor to shift FC operation into its high-efficiency region while sustaining charge.

Development and evaluation of a water-cooled fuel cell stack with porous rib GDL/MPL

Takumi Nunokawa･Aiko Miyata･Takumi Onda (SUBARU)･Mitsunori Nasu (ENOMOTO)･Makoto Uchida･Masahiro Watanabe (University of Yamanashi)･Naohide Yoshimura (SUBARU)

To reduce the processing cost of bipolar plates and to improve the volumetric power density of the cell, a water-cooled fuel cell incorporating porous rib GDL/MPL was fabricated. Furthermore, a short stack was constructed by stacking multiple cells. The power generation performance and the effects of this approach are reported.

Experimental Investigation of Hydrogen Storage and Utilization Technique using Hydrogen Absorbing Alloys for Light Duty Device

Sota Kato･Hikaru Komatu･Masataka Kosaka (Saitama Institute of Technology)

In recent years, changing the energy of a lot of devices including Light Duty Vehicle, Heavy Duty Vehicle and so on into hydrogen, have been trying. In many cases, the high pressure compressed hydrogen gas is used as power of these devices, so public use is difficult. In this paper, the hydrogen storage vessel using the hydrogen absorbing alloys that were possible to absorb and desorb the large amount of hydrogen gas at room temperature and normal pressure, for the Light Duty devices were developed and the characteristics of proposed unit were described.

Elucidation of Coupled Vibrations in Highly Damped Systems Using Modal Energy Contribution Analysis

Daichi Hiraiwa･Yuichi Matsumura (Gifu University)･Masato Hashioka･Masashi Komada (Toyota Motor)

A method has been developed to quantitatively analyze the modal contributions of individual subsystems to the steady-state response of high-damping systems at arbitrary frequencies, expressed in terms of energy quantities. This analytical method was applied to a finite element model that simplified the reproduction of vibrations causing road noise, and the results verifying its effectiveness are reported.

Full-Field Measurement of Transient Tire Vibrations Using Digital Image Correlation and Dynamic Mode Decomposition

Hailemichael Solomon Addisu･Yuki Kato (Kochi University of Technology)

Accurate measurement of transient tire vibrations is essential for vibration design and noise evaluation. However, conventional contact sensors are difficult to use on operating tires and offer limited spatial resolution. Image-based methods, such as digital image correlation (DIC), enable full-field structural measurements, but suffer from high-frequency noise and limited subpixel accuracy. To overcome these issues, this study integrates DIC with dynamic mode decomposition. The proposed framework was validated by 2D-DIC on an aluminum cantilever beam and then applied to 3D-DIC measurement of tire tread blocks.

Experimental Study on the Mechanism of Hot Judder in Automotive Disc Brakes

Kenya Sada･Takashi Nakae･Takahiro Ryu･Junichi Kitamura (Oita University)･Tsuyoshi Suzuki･Takuro Koseki･Hideaki Ikeda･Takahiro Horii･Tetsuya Noguchi (Akebono Brake Industry)

In automotive disc brakes, a pattern of heat known as a hot spot forms during high-speed braking, causing a vibration known as hot judder in the vehicle. To clarify the mechanism behind this phenomenon, the authors conducted experimental tests using a dynamometer, clarifying that the pattern repeatedly forms and dissipates, and that the number of such patterns increases over time.

Development of a Prediction Method for Vehicle Vibrations During Driving Caused by Constant Velocity Joints

Junichi Hirata･Daiki Suzuki･Hideto Fujiwara (NTN)

A component-based Transfer Path Analysis (TPA) using 6 degrees of freedom virtual points is applied to investigate the contributions of vibration transfer paths to lateral vehicle vibration caused by constant velocity joints during driving. Based on the investigation results, a simplified prediction formula for lateral acceleration at the vehicle evaluation point is developed. Predicted values are calculated using the thrust forces induced by the constant velocity joints obtained from kinematic analysis and are compared with measured values.

Application of a Real-Time Noise Prediction System to Steering Noise Development

Keiji Hara･Hiroki Fukasawa･Hidekazu Muto･Nobuyuki Himeno (Estech)･Mitsutaka Nakamura･Jun Ishio (Honda R&D)

To achieve front-loading in steering noise development, a bench evaluation environment capable of capturing sound variations caused by subtle differences in input is required. In this study, a real-time acoustic prediction system based on transfer path analysis was developed for full-vehicle noise prediction and auditory evaluation. The system was applied to steering noise development.

Exploration and Evaluation of Psychological Burden Factors Experienced by Vehicle Occupants in Traffic Environments
-A Data-Driven Approach Using Natural Language Processing-

Nichika Asai (Salesforce Japan)･Ritsuko Iwai (R-IH, RIKEN)･Takatsune Kumada (Kyoto University)

In recent years, autonomous driving technology has rapidly advanced; however, the subjective comfort of vehicle occupants has not yet been sufficiently investigated. Therefore, this study explored traffic environments that induce psychological burden on vehicle occupants, proposed an automatic questionnaire generation method using natural language processing and large language models, and examined the relationship between the constructed psychological burden scale and occupants' personality traits.

Effects of Foreground Visual Stimuli on Ride Comfort Evaluation in Autonomous Vehicles

Yuya Satsu･Junya Tatsuno (Kindai University)･Kazuma Ishimatsu (Jikei University)･Setsuo Maeda (Nottingham Trent University)

This paper aims to develop guidelines for the interior design of fully autonomous vehicles, as such vehicles do not require 360-degree windows and therefore allow for the introduction of new interior concepts. To investigate the effects of presenting visual information different from the surrounding scenery on ride comfort evaluation, driving simulator experiments were conducted using three displays. During the experiment, 20 participants evaluated the discomfort caused by whole-body vibration while passing through a vibration section on the test course. The results suggest that differences in foreground visual stimuli may affect ride comfort evaluation even under identical vibration conditions.

Objective Evaluation Method for In-Cabin Sound Quality in Electric Vehicles (Second Report)
-Sound Quality Evaluation Method for In-Cabin Sound-

Kenya Fujii･Kenji Torii (Honda R&D)

The authors have been investigating methods for quantifying the in-cabin sound quality of electric vehicles. In the previous report, sound quality evaluation indices for in-cabin electric powertrain noise were developed. Based on this work, a new subjective evaluation experiment targeting overall in-cabin sound, rather than only electric powertrain noise, was conducted. This report presents the results and clarifies the important sound quality factors required for comprehensive enhancement of in-cabin sound quality in electric vehicles.

Objective Evaluation Method for Interior Sound Quality in Electric Vehicles (Third Report)
-Preliminary Validation of Interior Sound Quality Indices and Proposal of a Sound Quality Map-

Kenji Torii･Kenya Fujii (Honda R&D)

The authors have previously shown that reducing loudness and tonal noise originating from the electric powertrain is important for improving the in-cabin sound quality of electric vehicles, and corresponding objective evaluation indices were developed. In this report, the validity of these indices is verified through subjective evaluation experiments conducted by experts. In addition, a sound quality map for visualizing sound quality differences among vehicles is proposed.

Analysis of the Effect of Driving Workload on an Engine Noise Perception Prediction Model Using Time History of Vehicle Parameters

Shinichi Suganuma (Chuo University)･Shimpei Nagae (Nissan Motor)･Takeshi Toi (Chuo University)

In a previous study using on-road driving data, the highest accuracy was obtained when a 5.5-second time history of engine speed was added to an engine noise perception prediction model that used vehicle parameters as explanatory variables. To clarify how variations in driving workload influence the time-history effect, the present study used a driving simulator in which driving workload was changed by varying driving environments and driving conditions. The resulting variation in the time-history effect was examined to analyze the cognitive structure of engine noise perception.

Contribution to improving drivability through the development of a quantitative system for NV sensory evaluation

Hiroyuki Hiroyuki Kimoto Kimoto･Shunsuke Rikitake･Masao Yano･Yuta Yamakita･Kunihiro Nobuhara･Hitoshi Yoshimura (Toyota Motor)

While NV analysis and evaluation are crucial for improving stability, quietness, and feel, it has been difficult to assess the sensory that do not rely on skilled workers. we present our method for assessing the effect of static electricity elimination on improving drivability and feel using our data analysis system (WAVEBASE).

Development of quietness for new compact SUV with third-generation e-POWER unit

Riku Sekine･Ryo Matsunaga･Takayuki Miyakawa･Masahiro Kanayama･Yukihiro Mori (Nissan Motor)

The first and second generation e-POWER systems already on the market have been gotten good reviews for EV-like quietness. We developed the third-generation e-POWER unit, achieving both high efficiency and quietness by combining a generator engine (HR14DDe engine) with a 5-in-1 system. This paper introduces Quietness development of the new compact SUV equipped with the third-generation e-POWER.

Quietness Improvement Technologies for New Generation MINIVAN equipped with fully electric drive system

Yuki Namai･Kazuhisa Okada･Yukihiro Mori (Nissan Motor)

This paper introduce the technology to improve the quietness of the next minivan, which is equipped with a third-generation e-POWER unit that achieves both high efficiency and low noise. The adoption of a high-rigidity platform and high-performance soundproofing materials achieves class-leading quietness.

Introduction of the next generation Active Noise Control for engine noise and road noise

Haruna Aimi･Wataru Ogose･Daisuke Ochi･Kazuhisa Okada･Yukihiro Mori (Nissan Motor)

Active Noise Control (ANC), which is adopted to Nissan ICE or e-POWER vehicles, is a system corresponding to a single frequency to reduce the engine rpm order. Otherwise the new ANC system is corresponding to a broadband frequency which deal with both engine generation noise and road noise, and adopted to the Nissan new minivan first in the world. In this lecture, we will present the concept for realizing high performance ANC.

Test Method for Unification and Luxury of Operating Interior Electric Curtain Noise

Sangkyun Ahn (Hyundai Motor)

Recently, the electrification of indoor parts has been rapidly progressing. In order to develop a sense of unity, luxury, and differentiation by utilizing statistical techniques, we intend to present new development criteria by matching noise measurement factors with emotional variables. Through this evaluation method, we intend to provide differentiated interior sound sensibility to our customers. This study was conducted in The order of developing emotional quantification factors and securing noise measurement and emotional data in Section 2.1, verifying significance factors through statistical analysis in Section 2.2, and establishing guidelines for differentiation, luxury, and uniformity in Section 2.3. Finally, the actual project verification was conducted through the Genesis large flagship SUV in Section 2.4

A Study on Vibration Devices for Vehicle Interior Applications

SeokHwan JI (KOMOS)

The automotive industry is developing technologies to improve driver convenience and safety through autonomous driving and in-vehicle interface systems. Interest in haptic systems using vibration motors has increased. This study investigates the structural and performance characteristics of vibration motors for vehicle interior applications. The motors must ensure stable vibration transmission, low noise, structural reliability, and proper thermal characteristics within limited spaces. Therefore, stiffness, noise, heat generation, strength, and sensitivity characteristics were analyzed and evaluated to verify the performance of vehicle interior vibration motors.

Development of MBD method that simultaneously considers power management, thermal performance, vehicle motion performance, etc by using the cross-domain model
-Part II: A Multivariate Optimization Case Study Based on Cross-Domain Model Results-

Aoto Utsumi･Shigemitsu Takahashi･Mayuka Ojima･Masayuki Kiyono (Nissan Motor)

In this study, we present a case study on the application of multivariate optimization to overall vehicle design that accounts for trade-offs among multiple performance attributes, using output results obtained from the cross-domain model CAEM (Collective Automotive Engineering Model), reported in Part 1, which integrates multiple performance domains, such as fuel economy and handling stability, belonging to largely different physical domains. The study confirms that overall vehicle design can be optimized with respect to the selection of design variables and modules.

Development of an MBD Method for Global Design Optimization Using Cross-Domain Models
-Report 3 Efficiency Improvement of Analysis, Evaluation, and Data Management Using LLMs-

Shigemitsu Takahashi･Aoto Utsumi･Masayuki Kiyono (Nissan Motor)

Global optimization utilizing cross-domain models significantly increases the amount of knowledge and decision-making speed required from engineers, making human capability the limiting factor. To address this issue, we structured data and interfaces on the premise of enabling both LLMs and engineers to access knowledge and execute analyses, thereby improving overall engineering efficiency.

Improving Bracket Design Efficiency Through CAE and AI Integration

Mikito Kawamura･Toshiki Terabe･Chika Kanba･Makoto Okawa･Takumi Sano (Toyota Motor)

In bracket design, reducing the development cycle while simultaneously satisfying multiple performance criteria such as noise and vibration (NV) and thermal stress is essential. Conventional CAE-driven design workflows, however, depend heavily on iterative trial-and-error evaluations and thus provide limited scope for time reduction. This study expedites the exploration of exhaust manifold bracket designs by integrating surrogate modeling and generative shape optimization with CAE simulations. We demonstrate that the combined approach significantly accelerates design space exploration and improves solution discovery, and we discuss the method’s practical benefits, limitations, and operational challenges encountered during implementation.

Development of a Design Space Exploration Method for Structural Members under Manufacturing Constraints

Tetsuya Ishigai Ishiga･Kohei Shintani･Mashio Taniguchi･Tomohito Sono･Sho Yamanaka･Hayata Morita (TOYOTA Mortor)

In recent automotive development, the use of shape optimization and machine learning has been increasingly explored to shorten development lead time. However, for practical vehicle development, a systematic process has not been fully established to generate feasible cross-sectional shapes within manufacturing constraints and to present multiple effective design candidates for decision-making. This paper proposes a design support process that integrates cross-section shape generation and design exploration. By using a generation method capable of producing realistic part-like shapes composed of flat regions and filleted regions, the proposed process enables efficient presentation of multiple design candidates in the early design stage.

Simultaneous Material and Shape Optimization of EV Battery Plates Using Surrogate Models Trained on Limited Samples

Hiroyuki Saito･Takayuki Michishita･Kotaro Kawajiri (AIZOTH)

In designing EV battery plates responsible for heat dissipation, both thermal and mechanical strength requirements must be satisfied simultaneously. This study presents a method that enables real-time prediction and simultaneous material and shape optimization by utilizing a high-accuracy surrogate model for thermo-structural physical field prediction, constructed through limited-sample learning.

Target Cascading of Tire Performances using Machine Learning

Yeonsang Yoo (Hyundai Motor)･Benjamin Schaefer (RWTH Aachen University)･Yongdae Kim･JinSil Kyeong (Hyundai Motor)

The automotive industry is shifting towards Model-Based Systems Engineering (MBSE) to manage increasing complexity in development. However, virtual tire development has a significant limitation: setting tire performance targets in early stage is difficult without physical testing. To overcome this situation, this study proposes a Target Cascading (T/C) process to derive tire performance targets directly from vehicle performance requirements and validated the process. Previously developed performance prediction models were improved for refined T/C process. Additionally, a GUI was developed to integrate the prediction models and T/C process for user convenience.

Parameter estimation for spot-weld fracture prediction models using data assimilation

Risako Ito･Yoshiteru Ishibashi･Taichi Sato･Yasuhiro Tosaka (Nissan Motor)

Regarding fracture prediction of spot welds in FEM analysis, the current major method is based on load criteria. Recently, more detailed spot weld models have been proposed in order to reproduce the spot weld failure based on multiaxial stress state under combined loading on the heat-affected zone (HAZ), where fracture initiates. However, it is difficult to directly measure the material properties of the HAZ through experiments. In this study, data assimilation is applied to estimate the material properties of the HAZ.

Study on Crash Analysis Correlation of Aluminum Die Casting Components Using Simplified Casting Simulation

Kenichiro Fukagawa (Honda R&D)

In recent years, the application of aluminum die castings to automotive body structures has been expanding. Aluminum die castings exhibit material property distributions, and reflecting these distributions is important for achieving accurate crash analysis correlation. Prediction methods for such distributions include casting simulation; however, issue remain for application in the early stage of development. In this study, a method for predicting material property distributions using simplified casting simulation and applying the results to crash analysis, which can be implemented in the early stage of development, was investigated.

A Study on Fracture Analysis Using Isogeometric Analysis with Trimmed Solids

Shinnosuke Nishi･Tadashi Naito (Honda R&D)･Norio Shimizu (JSOL)

Isogeometric analysis with trimmed solids enables efficient modeling of complex geometries while maintaining high accuracy through high-order basis functions. In this study, we apply trimmed solids incorporating Lumped Assumed Strain elements to the fracture analysis of aluminum components under crash conditions. Comparative simulations using conventional FEM solid elements are conducted to assess differences in accuracy and computational cost. The results demonstrate the effectiveness of the proposed approach and provide insight into the underlying factors governing its effectiveness in fracture analysis.

Optimal Shape Design of Crash-Resistant Parts Using Linear Buckling Analysis

Ryo Ageba･Kazuhiko Higai･Toyohisa Shinmiya (JFE Steel)

To address increasing performance demands on impact components due to electrification and the need to shorten vehicle development time, shape optimization techniques are useful. However, crash analysis involves computationally expensive nonlinear analysis, making it unsuitable for shape optimization. This study developed an optimization method for impact components by using buckling strength obtained from linear analysis as the objective function.

A study on securing Torsional Stiffness in the Early Design Stage to Enhance Chassis Frame Durability

Namjin Kim･Gunwoo Nam･Geonhee Cheon･Eunsu Jang･Soosang Yoo･Hyun Sung･Jungsub Kim (Seojin Industrial)

Torsional loads during driving significantly impact the fatigue life and durability of a chassis frame. This study analyzes the correlation between torsional stiffness and durability performance. Initially, 1D element based analysis identified main design parameters regarding cross sections and thickness. These parameters were validated using a 2D flexible body finite element model for precise stiffness verification. Finally, durability analysis confirmed that increased stiffness effectively reducing stress and extends fatigue life. These results indicate that securing structural stiffness during the early design stage is critical for enhancing overall durability.

A Study of the Durability analysis method considering various contact conditions

JinHee Jang (Hyundai Motor)･DongJun Kim (Cadence)･MoonHo Yang (Hyundai Motor)

The durability performance directly related to safety is an item that must be satisfied. Because endurance testing requires a lot of cost and time, it is very efficient to evaluate simulation before testing. In this study, we examined the application of Nastran's recently developed Glue contact technology to the durability analysis of chassis components. And we developed a method to apply residual stress such as bolt pre-tension and pipe interference fit. Since the method implemented in this study can be used to study various boundary conditions in durability analysis.

Identification of High-Quality Tactile Requirements for an Instrument Panel through Friction Measurement and Fingertip Surface Visualization

Kazuki Yamagishi･Ran Nishikido･Yoshitomo Takahashi (Mazda)

Tactile feel at touchpoints, such as interior materials, varies significantly among individuals, making it difficult to quantify design requirements that often rely on expert heuristics. In this study, we measured friction during touch motions in several dozen participants and visualized fingertip-surface conditions for a subset of participants. Based on these results, we elucidated the friction mechanisms and performed statistical analyses to link subjective sensations to objective physical quantities.

Pre-verification of the development of the deco bezel specification steering wheel through analysis

Dongmin Kim (KOMOS)

When manufacturing automotive steering wheels, a high defect rate occurs during the manual leather stitching process. Therefore, we developed a steering wheel with a deco bezel specification that eliminates this manual leather stitching process to reduce the defect rate and allows for the application of a high-end design to the front of the steering wheel. Accordingly, this study pre-verifies the issues encountered during the development of the deco bezel specification steering wheel through analysis.

A Study on Partition Layouts for Configuring Independent Spaces in Vehicles

Jiseob Park (Hyundai Motor)･Jaemoon Jung (SeoYon E-Hwa)

This study proposes a partition layout for creating independent spaces in autonomous vehicles. Based on aircraft full-cover partitions, the design was redefined to suit limited vehicle interiors. A console-type partition was developed and evaluated through usability testing. The optimized design integrates a variable armrest, cup holder, smartphone mount, and PDLC film. The results verify its feasibility for improving privacy, convenience, and spatial independence in autonomous vehicle interiors.

The Development of Active Air Skirt for reducing Drag Force

Jinyoung Yoon･Soobok Kim (Hyundai Motor)･Jaesup Byun･Jangho Kim (hyundai Mobis)

There are various active air flaps, active rear spoilers, and active deflectors, which are various active aerodynamic devices to improve the aerodynamic performance of electric vehicle. This technology is an active air skirt that improves the air resistance of the front wheel tire by controlling the air flow in the front lower part and improves the air flow to the rear, and is deployed/stored according to the vehicle speed. As a result of conducting a wind tunnel test by applying it to a real vehicle, the effective CD (coefficient of Drag) value was confirmed, and mass production feasibility was confirmed through robust design of the actuator and operating mechanism.

Development of a Predictive Model and Identification of Influencing Factors for the Millimeter-Wave Transmittance of Coatings

Hironobu Kominato･Keisuke Yamakawa･Hiroya Ochiai･Tomokazu Okugi･Hiroto Matsui･Daiji Katsura (Mazda)･Takashi Yamamoto (Kogakuin University)･Takuichi Hirano (Tokyo City University)

We are developing high-performance bumper components capable of achieving a high level of both aesthetic quality and sufficient millimeter-wave transparency. To efficiently determine the formulation requirements for the metallic bright materials within the coating that attenuate millimeter-wave, this study constructed the numerical calculation model capable of predicting transmission performance with practical accuracy and identified the factors by which metallic bright materials influence transmission performance.

3D Measurement of the Baseline Direction in Stereo Cameras Using Image Magnification Ratio

Hideaki Kido (Hitachi)･Kota Irie (Astemo)

We propose a method for measuring 3D distances in the reference direction for fisheye stereo camera systems. This method estimates distances using image magnification under the assumption of a planar surface. Numerical simulations and experiments using computer graphics demonstrated that, when the angle of incidence is close to 90 degrees, this method achieves higher accuracy compared to conventional parallax-based measurement methods.

Feasibility of Embedding a Mini-LED Module in Laminated Glass for Automotive Lamp Applications

Sang Heon Wang･Nak Kyoung Kong･Kyung Hwan Kim (Hyundai Motor)･Jun Ho Bang (KCC Glass)･Jina Lee･Dong Hoon Cha (Seoul Semiconductor)

This study investigates the feasibility of a laminated-glass-integrated Mini-LED module for automotive lamp applications. A Mini-LED sample was embedded in laminated glass using a conventional automotive lamination process. Luminance comparison before and after lamination and high-temperature reliability tests were conducted to evaluate process compatibility and durability. The embedded module showed limited luminance change after lamination and satisfied predefined evaluation criteria after reliability testing. These results indicate the applicability of laminated-glass-integrated Mini-LED modules to future automotive lamp systems.

Research on Lamp System for Vision Sensor

Byoungsuk Ahn･Hyungsun Kim (Hyundai Motor)･Jungsub Lim･Hyunchang Hwang (Hyundai Mobis)

This study investigates the effect of high-definition micro-LED (HD) beam control on camera-based lane detection under nighttime driving conditions. Conventional low and high beam was compared with an HD adaptive lighting system across various road environments. Conventional lighting reduced lane recognition accuracy, particularly on curved roads and near reflective structures that induced glare. In contrast, the HD module enhanced lane visibility through precise light distribution control and maintained more stable recognition performance. These findings suggest that HD adaptive lighting may improve vision-based ADAS perception and enhance nighttime driving safety.

Considerations and Countermeasures for Reliability Design of BGA Solder Joints

Hisao Nishimori･Jun Muto･Yasufumi Shibata (Toyota Motor)

As electronic components become more advanced, designs increasingly place many BGAs—whose solder joints cannot be inspected visually—on the same board. This makes it essential to develop product designs and manufacturing processes that build in quality based on an understanding of failure modes. By characterizing BGA solder-joint conditions through both non-destructive and destructive analyses, this presentation introduces approaches to achieving robust designs that include manufacturing quality, drawing on international standards as part of the evaluation.

Manufacturing management approach with AI and statistical methods for improvement of Printed Circuit Boards manufacturing quality

Shunsuke Narita･Tai Horikawa･Tomoyuki Ueno (Nissan Motor)

High manufacturing quality is necessary for the realization of further advancement of printed circuit boards by the advancement of electronics in automobiles. We investigated a method to reconcile quality and efficiency by shifting manufacturing management from threshold-based management to distribution-based management. In this research, we propose the process of early generation of estimated distribution and outlier detection through the application of Bayesian Estimation from AI and ML processing capabilities.

Proposal for the Mechanism of Whisker Formation and Countermeasures from Sn Plating in High-Speed Communication Connectors: Part II

Jun Muto･Hisao Nishimori･Hitoshi Yakuden･Miiyu Orinaka･Yasufumi Shibata･Takashi Yamada (Toyota Motor)

In recent years, the shift to higher-speed communication has led to the adoption of connectors with various shield housings in automotive electronic components. Tin plating on zinc die-cast shield housings is known to produce whiskers driven by thermal stress. In this report, we present experimental results and, based on those findings, propose plating specifications predicted to suppress whisker formation.

Development of a simple evaluation method for abnormal heat generation phenomena in automotive ECUs under high-temperature environments

Koki Mori･Tai Horikawa･Fumito Kishi (Nissan Motor)

Electronic components can suffer random failures, and if current continues to flow after such a failure, abnormal heating can occur. Because automotive ECUs are used under more severe high-temperature conditions than ECUs for other applications, it is necessary to investigate the causes of such abnormal heating and to verify the effectiveness of countermeasure designs. This study proposes a method for constructing a simple high-temperature evaluation setup that does not require the use of costly temperature-controlled chambers.

Development of an artificial weather chamber that reproduces a dynamic weather environment for autonomous driving sensors (4th report)

Hemant SUBHAS Ningaraddi･Tatsuki Yoshida･Hiroyuki Enoki･Hisayasu Shima (ESPEC)･Ifuu Ooishi･Sou Igarashi･Masao Nakagawa (Doshisha University)

To facilitate the extensive adoption of automated driving technologies, novel methodologies for assessing the recognition capabilities of in-vehicle sensors, such as cameras and LiDAR, which are susceptible to the effects of diverse weather conditions, must be developed. This study evaluated the recognition performance of various sensor types, including those employed in automated driving systems, within a fog environment where the size of fog droplets and visibility were controlled using an artificial weather testing chamber.

A Study on SNN-Based Decision Models for Autonomous Driving

Katsuo Semmyo･Katsuki Tomita･Yuya Arima･Shuo Huang (NTT DATA Automobiligence Research Center)

Compared to conventional Artificial Neural Networks (ANNs), Spiking Neural Networks (SNNs), which mimic brain-like structures, offer advantages in low power consumption and low latency, making them promising for applications in automotive functions with demanding hardware requirements. As part of developing a decision model using reinforcement learning, we evaluate an SNN in a simplified experimental environment and discuss its potential.

Physics-Guided Two-Stage Anomaly Detection Framework for Industrial Connector Fitting Verification

Ryusho Itoh･Mako Sasaki･Koichi Ichige (Yokohama National University)･Hirotatsu Matsuo･Atsushi Ugaji･Matsutaro Hata･Kouji Abe (Nissan Motor)

We propose a physics-guided two-stage anomaly detection framework for industrial connector fitting inspection to guarantee zero-defect outflow. Stage 1 feeds CWT-based log-scalograms into a linear bottleneck convolutional autoencoder, suppressing over-generalization and scoring anomalies with a hybrid MSE–SSIM metric. Stage 2 applies a deterministic fail-safe layer evaluating intersection magnitude (IM) with a modified z-score, eliminating remaining false negatives. On five automotive connector types, Stage 1 achieved F1 = 99.36% on the most challenging connector and 100% on all others; Stage 2 completely eliminated false negatives. Under open-set conditions, recall was 99.97% versus 83.37% for CNN baselines.

Correlation between ESA Immunity Test Methods (Second Report)
-Influence of Circuit Impedance and Injection Point-

Shinichiro Itoh･Keiji Kobayashi (NALTEC)･Hitoshi Tsukahara (Japan Quality Assurance Organization)

Comparative measurements were conducted on the correlation between the ALSE method, BCI method, and RVC method, which are ESA immunity test methods specified in ISO 11452. The comparative measurements regarding the effect of different circuit impedances showed that the effect of circuit impedance was relatively small in these three test methods. Furthermore, comparative measurements regarding the effect of different injection points in the BCI method showed that the null point frequency may change depending on the injection point, and that the effect of induced voltage due to the injection point was relatively small.

Investigation of the Impact on Emission Performance during Chassis Dynamometer Testing

Katsumasa Aoki (Toyota Motor)

With changes in the market electromagnetic environment, EMC regulations are becoming stricter and the importance of ensuring EMC performance is increasing. Vehicle EMC emission limits are defined by standards such as CISPR 36, and on-road measurements performed on a chassis dynamometer are required. This paper examines the effect of static electricity generated during chassis dynamometer testing on emission performance.

Development of MILS Technology for Auxiliary Power Supply Control Systems

Takahiro Kinoshita･Yuki Hata (SUBARU)

This paper reports on the overview and achievements of MILS technology development for an auxiliary power supply control system.

Metrics for estimating driver inattention in level 2 automated driving

Nozomi Nakajima (Keio University)･Ryusuke Sagawa･Nobuhiro Mizuno･Akira Yoshizawa (DENSO IT Laboratory)･Tatsuru Daimon (Keio University)

This study investigated metrics for estimating driver inattention during Level 2 automated driving, involving reduced attention to monitoring the surroundings and immersion in thought. Using a driving simulator, we replicated inattentive states by assigning secondary tasks. We report the results of a comparative analysis of visual behavior characteristics between monitoring in an inattentive state and monitoring perceived as safe by the driver.

Detection of Driver's Unsafe Awareness Based on Dynamic Estimation of Forward Gaze Point

Manabu Sato･Hironori Suzuki (Toyo University)

This study detects the latent unsafe awareness of drivers on three-lane highways. Using a Preview Driver Model (PDM) and applying a particle filter to front-wheel steering angle data, the forward gaze point is estimated from the derived parameters. By visualizing this forward gaze point (which is typically difficult to measure directly) this research successfully verifies the detection and validity of drivers' unsafe awareness.

Driver and Passenger State Monitoring for Determining Appropriate Intervention Timing and Methods

Mieko Ohsuga (Osaka Institute of Technology/Wellnesslab)･Hiroki Takeuchi (University of Occupational and Environmental Health)･Yoshiyuki Kamakura (Osaka Institute of Technology)

As automated driving advances, the need for monitoring driver and passenger states is paradoxically increasing. One primary objective of this monitoring is real-time intervention. This presentation identifies the requirements and challenges for enabling interventions at appropriate timing and through suitable methods. Furthermore, we report insights obtained from an exploratory analysis of proprietary data.

Optimization of Multisensory Stimulation Based on Physiological Indicators
-Investigation of Stimulus Combinations Contributing to Arousal Enhancement-

Yurie Ogawa･Shinya Ohira･Yuto Korogi･Chie Fukuhara (Toyota Mortor)

To develop a system that enhances driver arousal, the effects of auditory, climate, and fragrance stimuli, as well as the amplification or attenuation resulting from their interactions, were quantified using subjective sensory evaluations and physiological measurements. In an actual vehicle environment, the results suggest that airflow direction from the climate system alters auditory perception and the distribution of fragrance, thereby affecting the magnitude of these effects. Based on these findings, guidelines for adjustments to vehicle controls to maximize the overall effect were proposed.

Effects of regional airflow from dual- and single-column fan-integrated carseat on body coolimg under a comparable resting skin-temperature environments

Hayato Takahashi･Kentarou Wada･Teruyuki Nagai (Kyoto Institute of Technology)･Tetsuya Kitagawa (Fortech Co. Ltd.)･Yukiko Nishizaki･Naoyuki Yamashita (Kyoto Institute of Technology)

This study investigated the effect of single- and dual-column fan configurations in a fan-integrated carseat on thermoregulatory responses under an ambient temperature of ~33°C, comparable to resting mean skin temperature. Fans were arranged in three and two rows in the backrest and seat cushion, using either dual- or single-column configurations. An airflow was delivered from both the backrest and seat cushion. Rectal and skin temperatures were measured throughout the experiment. Changes in rectal and mean skin temperatures did not differ significantly between the two configurations, suggesting that single-column fan configurations may be sufficient to maintain thermoregulatory responses at 33°C.

Analysis of a Participants Experiment on the Physiological and Psychological Responses due to the Low-Emissivity Glass in a Winter Vehicle Cabin

Yoshiichi Ozeki (AGC)･Yuuichiro Tsujimoto･Kan Shindo･Shin-Ichi Tanabe (Waseda University)

This paper investigates the effects of glass emissivity on the thermal environment inside a vehicle as well as on human psychological and physiological responses. We conducted an experiment in a vehicle cabin simulating a winter scenario with low-emissivity (low-E) and normal glass on each side. We measured the thermal environment around each type of glass and participants’ thermal sensation votes were collected. The experimental results indicate that the single low-E glass for automotive applications significantly improves the radiant environment and provides a thermal environment equivalent to that of low-E double glazing for architectural applications. Moreover, the low-E glass helped maintain higher skin temperatures and reduced cold sensations, as confirmed by a previously developed numerical model.

A Study on Estimating Occupant Thermal Comfort Using Facial Expressions and Physiological Indicator

Chikara Kawamura･Yuko Hara･Yuki Kodama (Mazda)･Toshio Tsuji (Hiroshima University)

We built a model using facial and physiological data to estimate thermal comfort and identified its effectiveness and technical issues.

Construction of an Accelerator Operation Prediction Model Based on Driving Data Clustering Considering Driving Characteristics

Takafumi Hosogi･Ryu Murotani･Susumu Sato (Institute of Science Tokyo)

In this study, real-world driving data were clustered based on driving characteristics, and an LSTM-based accelerator operation prediction model was constructed for each cluster. The proposed method aims to perform prediction that reflects the operational tendencies of each driving dataset. The experimental results showed that cluster-specific modeling improved the prediction performance of accelerator operation.

Study on an In-Cabin Biosensing Method Using Endocrine Indicators

Masaaki Nishi (Honda R&D)･Shintaro Izumi･Nobuhito Taniguchi･Yuto Noda (University of Kobe)･Toshihide Shiino･Yasushi Noguchi (Honda R&D)

To estimate occupants’ stress and comfort/discomfort states in a vehicle cabin, this study focused on the relationship between heart rate variability (HRV) and endocrine responses. HRV analysis windows were shifted backward from each saliva sampling time to synchronize continuous HRV features with delayed salivary hormone changes. A convolutional neural network (CNN) -based estimation model was then used to predict hormone dynamics, enabling successful classification of mental and physical stress states.

Impact of Trust Formation in Driver Assistance Systems on Drivers' Peace of Mind

Yousuke Furuya･Yoshihisa Okamoto･Taisei Kamio･Hiromasa Kenmotsu･Nanae Michida (Mazda)･Norihiro Sadato (Ritsumeikan University)

To enable drivers to enjoy driving with peace of mind, it is considered essential that they have trust in vehicle safety and driver assistance functions. We hypothesized that a key requirement for building such trust is that the assistance meets drivers’ expectations. Using a driving simulator experiment, we demonstrated that the formation of trust leads to increased peace of mind during driving.

Driver Accelerator Prediction using Real-World Environmental Parameters: Integrating a Brake Prediction Mechanism

Ryu Murotani･Takafumi Hosogi･Susumu Sato (Institute of Science Tokyo)

This research constructs a driver accelerator-prediction model from real-world environmental parameters (inter-vehicle distance, relative speed, road gradient, etc.) for vehicle simulations in the development phase. The model has two parallel prediction branches based on machine learning (LSTM/Transformer) : one predicts the accelerator pedal opening, and the other predicts the probability of braking. By integrating these outputs via a gating mechanism, the model improves overall accuracy, achieving particularly high prediction performance around vehicle stops.

Effects of Airflow Stimulation Considering Body-Part Sensitivity Characteristics on Drivers' Thermal Comfort and Arousal Maintenance

Jongseong Gwak (Takushoku University)･Yoko Hayashi (Institute of Science Tokyo)･Akinari Hirao (Shibaura Institute of Technology)･Motoki Shino (Institute of Science Tokyo)

To maintain drivers’ arousal while suppressing thermal discomfort, this study focused on body-part sensitivity characteristics to airflow stimulation under thermal environments and investigated the effects of airflow stimulation to the neck on thermal comfort and arousal level. The results indicated that, although the effects differed depending on the initial arousal state, airflow stimulation to the neck has the potential to maintain driver arousal while suppressing thermal discomfort.

Development of a Drowsiness Assessment and Prediction System (DAPS) for Commercial Vehicle Drivers: A Basic Study on Arousal Level Assessment Methods

Nobuhisa Tanaka･Tetsuya Niikuni (NALTEC)

We conceptualized a Drowsiness Assessment and Prediction System (DAPS) for commercial vehicle drivers to reduce drowsy-driving crashes by detecting declines in arousal during driving after the pre-duty roll call (tenko) and predicting the onset of drowsiness. Focusing on sleepiness-related changes in working memory and speech-related performance, we conducted an overnight, repeated-measures human-subject experiment in which tests assessing these functions were administered repeatedly. Test performance declined as sleepiness increased, demonstrating the promise of the indices used in each test.

Systematization of Traffic Disturbance Scenarios with Explicit Positional Relationships Among Traffic Participants on General Roads

Daisuke Miura･Hisataka Yoshida･Akiyoshi Hayashi (NTT DATA Automobiligence Research Center)･Mayu Mori (MEITEC)･Yoshitake Kozai (NTT DATA Automobiligence Research Center)･Ryo Hasegawa･Yuki Konishi･Hisashi Imanaga (JARI)

This study defines Pre-Logical Scenarios as an intermediate layer between Functional and Logical scenarios for traffic-disturbance situations on general roads. Targeting interactions with vehicles, motorcycles, bicycles, and pedestrians, we propose a unified six-element representation comprising road geometry, ego-vehicle behavior, ego-vehicle position, surrounding participant behavior, position, and direction. This common structure enables consistent scenario generation across all traffic participant types, facilitating a systematic transition toward Logical scenarios.

Development of Foundational Technologies for Comprehensive Safety Evaluation Against Traffic Disturbances Encountered by Automated Vehicles
-Integrated Extraction of Traffic Laws and Traffic Disturbance Scenarios Corresponding to Road Structures and Signs-

Hisataka Yoshida･Daisuke Miura･Akiyoshi Hayashi (NTT DATA Automobiligence Research Center)･Mayu Mori (MEITEC)･Yoshitake Kozai (NTT DATA Automobiligence Research Center)･Ryo Hasegawa･Yuki Konishi･Hisashi Imanaga (JARI)

This study proposes a method for comprehensively generating Pre-Logical Scenarios for traffic disturbances on general roads and systematically associating real-world constraints - including road structure, physical structures such as guardrails, and traffic-law regulations - with each scenario to enable structured extraction of scenarios relevant to safety evaluation. An automated tool implementing this method was developed as a foundational technology for comprehensive safety evaluation of automated driving systems. Case studies were conducted to demonstrate its practical applicability.

Development of a Real-Time Intersection Risk Prediction Method Utilizing Two-Dimensional Occupancy Grid Maps

Hironori Chaya･Heishiro Toyoda (Toyota Mortor)

This study proposes a real-time risk prediction method for intersections. Using traffic data observed on-site, the proposed method considers signal states and speeds separately for vehicles and pedestrians and efficiently extracts future near-miss risks and their potential hazards based on past similar situations. Such a framework enables us to holistically and simultaneously predict potential conflicts among multiple traffic participants.

A Study of Careful Driving Behavior in Right-Turn Maneuvers at Intersections by General Human Drivers

Yuki Manabe･Toru Kojima･Akihiro Abe･Mamoru Takushima･Kouichi Kitada (NALTEC)

To investigate referential human driving behavior for automated driving vehicles, including harmony with surrounding traffic, a driving simulator study was conducted on cautious driving behavior of general human drivers in situations where they may approach an oncoming vehicle while making a right turn at an intersection.

Study on High-Precision Estimation Methods for Vehicle Trajectory Using Drive Recorder Video and 3D-LiDAR Data

Hideki Matsumura (NALTEC)･Kazuki Tainaka (Tokyo Metropolitan University)･Kotaro Ishizuka (Institute for Traffic Accident Research and Data Analysis)･Motoki Sugiyama (nstitute for Traffic Accident Research and Data Analysis)･Naoyuki Kubota (Tokyo Metropolitan University)

To prevent traffic accidents or mitigate their damage, it is necessary to investigate their causes. For this investigation, it is important to reconstruction the accident as reliably as possible. In this study, we studied a method for high-precision estimation of driving trajectories using drive recorder video and 3D-LiDAR data to enhance the reliability of accident reconstruction.

Study on Accident Reconstruction and Its Usefulness Using Combined Drive Recorder Video and EDR Data and with High-Precision Estimation Results of Vehicle Trajectory

Kotaro Ishizuka (Institute for Traffic Accident Research and Data Analysis)･Hideki Matsumura (NALTEC)･Kazuki Tainaka (Tokyo Metropolitan University)･Motoki Sugiyama (Institute for Traffic Accident Research and Data Analysis)･Naoyuki Kubota (Tokyo Metropolitan University)

Regarding accident reconstruction, which is important for investigating the causes of traffic accidents, the authors proposed an objective and quantitative method using EDR data and drive recorder video, as well as a high-precision driving trajectory estimation method using drive recorder video and 3D-LiDAR data. In this study, these methods were applied to reconstruct an actual accident and analyze it.

Application of Particle-Based Simulation in Vehicle Corrosion Protection Development

Yoshiki Matsumoto (SUBARU)

Conventional corrosion protection development for automotive components has relied heavily on specification selection based on past knowledge and on physical vehicle evaluations, often resulting in a trial-and-error process. In this study, a vehicle water exposure analysis employing coupled particle-based simulation and structural analysis was introduced. By accounting for deformation of a resin cover caused by water pressure, the ingress of mist into the engine compartment was successfully reproduced, thereby improving the accuracy of desk-based evaluations.

Bayesian Estimation of the Time Evolution of Corrosion Amount in Automotive Components Using Field Corrosion Data

Atsushi Tokunaga (SUBARU)

Due to the limited sample size and big variances in corrosion data from field-recovered components, some adjustments are needed for regression analysis of corrosion amount over time challenging. This study proposes a Bayesian statistical method to estimate statistically reasonable time evolution of corrosion amount and to accurately estimate the upper tail of the probability distribution. An extended approach incorporating automotive sales plans is also introduced.

Evaluation of Corrosion Resistance of Aluminum Components by Low-Temperature Sealing

Shintaro Ono･Haruhiko Murakami･Masahiro Fujita (Suzuki Motor)

Since outboard motor engines use seawater for cooling, high corrosion resistance is required for cooling channels with complex geometries. In this study, we developed a new surface treatment technology that combines an anodization process with low geometry dependency and a novel sealing process that achieves both heat and corrosion resistance at low temperatures and in a short time. In this paper, we report the performance evaluation results of this technology and demonstrate its effectiveness.

Mechanistic analysis of degradation phenomena considering electrode–electrolyte interfaces

Kazuhiro Sakuramoto･Keisuke Shirai (Toyota Industries)

At electrode–electrolyte interfaces that control battery performance and lifetime, complex phenomena such as electric double layers occur, making experiments and conventional simulations difficult. This study uses simulations to analyze interfacial structures and demonstrates applications to Al-related corrosion phenomena.

Correlation Study Between the New JASO M 609 Method and Accelerated Evaluation Method for Corrosion Resistance

Tatsuya Ezaki･Teruaki Asada (Mazda)

For the development of high-quality rust prevention in automobiles, a highly accurate and efficient method for evaluating the corrosion resistance of coatings is crucial. Recently, the new JASO M 609 method has been established as a corrosion testing method with higher market correlation. The accelerated evaluation technology developed to efficiently assess corrosion resistance also correlates highly with this new JASO method and is effective for developing high-quality rust prevention in a wide range of applications.

Analysis of the Relationship Between Solvent Diffusion Behavior and Polymer Chain Relaxation in the Chemical Resistance of Automotive Interior Decorative Films

Takito Shibuya (Honda R&D)

In this study, white discoloration in automotive interior decorative films was found to be partly caused by void formation induced by the ingress of limonene, a principal component of citrus-based fragrances. Uptake analysis and dynamic mechanical measurements revealed that variations in acrylic composition alter diffusion behavior through differences in chain relaxation characteristics. These differences were shown to influence whitening associated with void formation. Based on these findings, design guidelines for acrylic layers with enhanced chemical resistance are proposed.

Development of an In-Situ Tensile Testing Method for Fire-Resistant Resins at High Temperature and During Combustion
-Comparative Evaluation of Resin Composite Materials for Battery Packs-

Satoshi Enokida･Kouhei Kajitani･Atsushi Yuki (Daikyonishikawa)･Yuki Yamada･Shuhei Yasuda･Junichi Ogawa (Mazda)･Masayuki Okoshi･Asami Nakai (Gifu University)

With the widespread adoption of battery electric vehicles (BEVs), structural safety requirements under fire conditions have become increasingly stringent. However, evaluation methods for the mechanical properties of resins during high-temperature combustion processes have not yet been established. In response, the authors developed an in-situ tensile testing apparatus capable of performing tensile tests during resin combustion. In this study, two types of resin composite materials applicable to battery pack structural components were evaluated. The results demonstrate that the sheet molding compound (SMC), which forms a char layer during combustion, exhibits superior strength retention.

Study on Non-Destructive Evaluation of Fiber Content for Advanced Quality Assessment of Recycled CFRP
-Thermal Diffusivity Measurement Using Active Thermography-

Atsushi Akai (Kyoto University of Education)･Yukihiro Hamada (Toyota Motor)･Yasumoto Sato (Toyota Central R&D Labs.)･Atsushi Mikuni (Toyota Motor)

Recently, recycled carbon fiber reinforced polymer (recycled CFRP) composites, which are made from recycled fibers, have attracted considerable interest. In the quality assessment of recycled CFRP composites, non-destructive evaluation of fiber content uniformity is important. As an indicator reflecting the through-thickness fiber content in CFRP composites, we focused on their out-of-plane thermal diffusivity. In this study, active thermography using a flash lamp was applied to CFRP composites to measure their out-of-plane thermal diffusivity. Furthermore, the feasibility of evaluating fiber content using the out-of-plane thermal diffusivity was investigated.

The Effect of Substrate Grain Size on Coating Microstructure and Bearing Performance in Multilayer Plating Materials for Engine Bearings

Yuhei Maegawa･Ryuji Kanaya･Yuma Haneda (Daido Metal)

With the aim of improving fatigue resistance for multilayer plating, we examined the control of the substrate microstructure by grain size. The grain size of the substrate can be reduced by changing the amount of metal added, which also affects the grain size of the multilayer plating. The study showed that controlling the grain size of the substrate can change the stress dispersion and crack progress behavior, potentially contributing to improved bearing performance.

Evaluation of Liquid Metal Embrittlement and Spot Weldability in E-Coated, Galvannealed 1.8 GPa Hot-Stamped Steel

Wook Jin Oh･Chang Wook Lee･Dong Ha Kang･Youn Il Jung (Hyundai Motor)･Je Youl Kong･Dong Hyun Kim･Jae Wook Kang (Hyundai Steel)

This study investigates the effects of E-coating on mechanical properties, spot weldability, and liquid metal embrittlement of galvannealed (GA) 1.8 GPa hot-stamped steel. GA steel shows superior elongation and bending performance with Al-10Si coated steel. Liquid metal embrittlement is controlled by heat treatment conditions, requiring adequate holding to suppress zinc penetration. Resistance spot weldability is maintained despite surface oxidation. These results support GA hot-stamped steel application in automotive structural components.

Standard Harmonization in Hydrogen Embrittlement Evaluation Using Equivalent Metrics

Amon Kimura･Satoshi Mizokami･Mitsugi Fukahori (Mazda)

The demand for vehicle weight reduction and improved crash safety has led to the increased application of high-strength steel sheets. For high-strength steels, addressing hydrogen embrittlement is one of the critical reliability issues, and the establishment of appropriate evaluation methods is required. This study reports a method to achieve equivalent hydrogen embrittlement evaluation using four-point bending and U-bend tests employed in domestic and international standards.

Evaluation of Hydrogen Embrittlement Resistance under Dynamic Loading Conditions

Susumu Maeda (Honda R&D)･Junya Suzuki (Honda Motor)･Tatsuya Houda (Honda R&D)･Hideki Tanaka (Honda Motor)･Shuji Ichijo･Mizuki Nihira･Kazuto Goto (Honda R&D)

The mechanism of hydrogen embrittlement under dynamic loading, such as in bearings, has remained unclear, and no definitive conclusion has been reached. In this study, we investigated the effects of additives on oil film formation and the influence of vibration under actual operating conditions to clarify the mechanism and obtained meaningful insights. Furthermore, a practical indicator for evaluating hydrogen embrittlement strength applicable to real operation was established.

Trends in Elderly Drivers Population and Related Accidents in Japan

Yoko Kato･Yasuhiro Matsui･Michiaki Sekine (NALTEC)

Japan is experiencing population aging. Meanwhile, due to increasing automobile dependence and generational changes in driving experience, the proportion of elderly drivers may be increasing at a faster pace. This presentation quantitatively shows the increase in elderly drivers and discusses annual trends in accidents frequently associated with elderly drivers, such as pedal misapplication accidents.

Relationship Between UX Evaluation of Electric Mobility for Older Adults and Physical/Cognitive Functional Characteristics

Hiroshi Watanabe･Hiroshi Yamazaki (AutoTechnicJapan)･Shu Moriyama･Kenshin Muto･Eiko Takano･Izumi Kondo (NCGG)

A User Survey of Personal Mobility Devices Was Conducted in a Demonstration Project for Supporting Mobility Among Community-Dwelling Older Adults. The Relationship Between Physical/Cognitive Functions and UX Evaluations of Two Mobility Models Was Analyzed. The Results Suggested the Importance of Selecting and Adjusting Mobility Devices According to User Characteristics.

Impact of VR Training on Safety Confirmation Behavior Based on Individual Characteristics of Older Drivers

Yuki Yoshihara･Linjing Jiang･Nihan Karatas･Asuka Harada･Hitoshi Kanamori (Nagoya University)･Motoshi Kojima (Toyota Motor)･Takahiro Tanaka (Nagoya University)

An intervention study using VR training was conducted with older drivers to examine its effects on safety confirmation behavior in actual vehicle driving. Drivers with safety-oriented characteristics showed a positive correlation between training performance and on-road confirmation behavior, suggesting that driver characteristics influence the transfer of training effects.

Elucidation of Accident Risk Structure in Older Drivers Based on an Integrated Analysis of Driving Aptitude Tests and Surveys on Lifestyle, Health, and Driving Awareness
-Study on Driver Characteristics for Delaying Driving Cessation (50)-

Shunji Taniguchi･Rin Ito･Hirofumi Aoki (Nagoya University)

This study integrates survey data on lifestyle, health, driving behavior, and safety awareness with results from driving aptitude tests to conduct a multifaceted analysis of accident risk structures. The findings confirm pathways whereby health decline increases accident risk through impaired cognitive function, and reveal discrepancies between self-assessed and actual driving abilities. Furthermore, the relationship with the perceived necessity of ADAS is clarified, and directions for effective safety interventions are proposed.

A Study On Optimizing Automotive Air Conditioning For Cabin Comfort

Jun Suzuki･Masaharu Marumoto･Akane Masui･Koki Kawakami･Akira Togi (Mazda)

In order to improve the comfort of automotive air conditioning and reduce energy consumption, we developed a CFD surrogate model that quickly calculates convective airflow in the cabin. Using parameter studies and optimization, we clarified how air conditioning blowing conditions (air volume, distribution, etc.) affect the temperature field and velocity field distribution near different parts of the human body.

Experimental Validation of Reynolds-Averaged Turbulence Models for Air-Conditioning Supply Jets in a Vehicle Cabin

Kazuki Ito (Hiroshima University)･Masahiro Morishita･Kouhei Mutou (Highly Marelli Japan)･Takuji Nakashima (Hiroshima University)･Itsuhei Kohri (Tokyo City University)･Yoshiichi Ozeki (AGC)･Minoru Inoue (Mazda)･Kazuhiko Matsunaga (Kanagawa Prefectural Junior College for Industrial Technology)･Hidemi Mutsuda (Hiroshima University)

Accurate evaluation of occupant equivalent temperature in vehicle cabin air-conditioning requires heat-balance prediction that accounts for convective heat-transfer coefficients. Therefore, improving HVAC airflow prediction remains important. This study investigates a supply jet and validates the reproducibility of turbulent energy transport mechanisms in the Realizable k–ε model through comparison with measurements obtained using a high-response multi-hole probe. Based on the results, challenges for further improving prediction accuracy are clarified.

The Effect of Reducing the GWP of Refrigerants on the Heat Transfer Performance of Oscillating heat pipe

Rikuto Dogan (Tohoku University)･Yasutaka Negishi･Asuka Bunno･Yuji Mihara (Daikin Industries)･Ayuki Kano･Ayumu Shimizu･Hiroki Nagai (Tohoku University)

Oscillating heat pipe (OHP) have attracted attention as thin, lightweight, and high-heat-spreading devices. This study aims to apply OHPs to mobility applications and experimentally investigates the heat transport performance of an OHP filled with R474B, a next-generation low-GWP refrigerant. Through the measurements of internal pressure and tube wall temperature, as well as comparisons with other refrigerants, the effects of differences in refrigerant properties on the heat transport performance of the OHP were evaluated.

Fundamental Properties of POE Refrigeration Oils for Low GWP Refrigerants

Yusei Minagawa･Tomohiro Takaki･Ken Sawada･Tsukasa Sakuraba･Yuya Mizutani (ENEOS)

In recent years, refrigerants with low global warming potential (GWP) and low environmental impact have attracted attention in the field of refrigeration and air-conditioning systems. This report presents evaluation results for various properties of refrigeration oils used to lubricate refrigeration compressors under the conditions of low GWP refrigerants such as R290 (propane).

Development of a 1D Simulation Model for BEV Thermal Management Systems
-(Part 2) Modeling of Oil Behavior in the Refrigeration Cycle-

Yu Yamashita･Yosuke Yasuda･Yusuke Sato･Tomohiro Sudo (DENSO)

Thermal management systems for BEVs have seen increasing diversification of operating modes, raising the demands placed on the refrigeration cycle that lies at their core. The compressor, in particular, is lubricated by oil dissolved in the refrigerant, making it essential to achieve both adequate lubrication and high efficiency. In this report, we present an original model that predicts oil behavior within the cycle based on the underlying physical phenomena, and demonstrate that it reproduces measured values from actual equipment with high accuracy.

Study on Thermal Management System utilizing Next-Generation Refrigerant for future xEV

Ryo Michikawauchi･Hiroyuki Sugihara･Atsuharu Ota (Toyota Motor)･Yuichi Kami (DENSO)

Considering the European PFAS regulatory landscape, thermal management system for xEVs was investigated using propane refrigerant as a non-PFAS alternative with superior cabin comfort energy efficiency and battery thermal control performance. To enhance safety, refrigerant circulation is restricted outside the cabin by adopting a coolant-based secondary loop with newly integrated chiller and cooler core components. While this architecture may increase system complexity, a simplified thermal circuit with reduced refrigerant charge was designed. Feasibility was confirmed through analytical evaluation.

Formulation design for long-life low-conductivity battery coolants

Yasuaki Kodama (Toyota Motor)･Ryo Karasawa･Takumi Otsubo (Japan Chemical Industries)

In battery electric vehicles (BEVs), battery cooling system safety and reliability are critical under high-load and high-temperature conditions such as rapid charging and high-power driving. Low-electrical-conductivity coolants reduce the risk of abnormal heating due to leakage; however, conductivity increases over time because of ethylene glycol oxidation and ion dissolution from components. This study identified flux-derived ions from aluminum brazing as a key factor. The use of optimized aluminum corrosion inhibitors effectively suppressed ion dissolution and stabilized conductivity during long-term circulation. The developed coolant formulation extends service life and has been applied to battery cooling systems since 2025, ensuring electrical safety and durability.

Thermal-Flow Stabilization Design of a Coolant Heater for Electric Vehicles

Daeseong Han･Jung Han Kim･Dae Nyeon Kim (Gyeongbuk Institute of IT Convergence Industry Technology)･Il Hwan Yi (Kumoh National Institute of Technology)･Jaehwan Jeong (DHG)

This study analyzed the outlet coolant temperature characteristics according to the flow channel design of a coolant heater. CFD simulations were conducted under conditions of 8 kW heating power and 10 L/min flow rate to evaluate the outlet coolant temperature and derive an optimal flow channel design. The results confirmed that the flow channel structure attached to the heating plate was effective in improving heat transfer performance and generating coolant turbulence.

Investigation of the Effect of Automotive Tire Tread Patterns on Vehicle Aerodynamic Drag

Shingo Ida･Masahiro Nagase (Sumitomo Rubber Industries)･Satoru Yamada･Ikuo Tanaka (Dassault Systems)

To reduce vehicle running resistance, the effect of differences in tire tread patterns on aerodynamic drag was investigated. Using two types of vehicles for CFD analysis, it was found that variations in tread patterns can change the tire drag contribution (CD) by up to 0.003 for all four tires combined. Additionally, differences in tread patterns were found to influence the flow field behind the vehicle.

Investigation of an Index for Evaluating The Aerodynamic Drag Reduction Effect of Full Wheel Covers

Mitsuharu Takeda (Suzuki Motor)

In Kei cars, steel wheels combined with full wheel covers are commonly used, and the styling of the wheel covers has an influence on aerodynamic performance (ΔCd). In this study, a simple index based on the opening configuration in a specified region near the inner side of the wheel cover outer edge is proposed. A clear correlation between the proposed index and ΔCd was confirmed, indicating that the proposed index has potential as an aerodynamic evaluation metric in the styling design stage.

Analysis Method for Airflow around a Vehicle Considering Electrostatic Charging, Surface Ion Neutralization, and Electrostatic Force Fluctuation by Vehicle Motion

Naohito Takasuka (SOKEN)･Kazuhiro Maeda (Toyota Mortor)･Noboru Maeda (SOKEN)

In the previous study, flow variations induced by vehicle electrostatic charging during driving were clarified through numerical analysis using a simplified step model that couples three physical fields: fluid flow, electrostatics, and charge transport. In this study, variations in tire-induced charge input, ambient positive air ions, and surface neutralization were further considered, and the influence of each factor on the airflow was evaluated.

Construction of Online Co-Simulation Environment
-(7th report) Fundamental Investigation of MBD for OBD-

Kenichiro Ogata･Daijiro Nakamura･Takashi Tsurumaki (Honda R&D)･Michinori Tani (Honda Motor)･Toshiharu Fukushima･Yohei Okagawa･Yutaro Tanimoto･Takuya Honjo (Honda R&D)

A highly efficient power unit development process based on Model-Based Development (MBD) is essential to achieve timely mass production of automobiles. However, On-Board Diagnostics (OBD), which is one of the regulatory requirements for mass production, involves fault diagnosis of vehicle systems and therefore typically requires the use of actual vehicles in the later stages of development. As a result, a full transition to a highly efficient, model-based development process remains challenging. This study focuses on an evaporative leak diagnostic function of the fuel tank system under OBD regulations and investigates the applicability of MBD to this regulatory domain

Development of a Method for Predicting Ambient Temperature of In-Vehicle Electronic Components Using 3D Fluid Analysis
-(Second Report)-

Takafumi Okumura･Hisao Nishimori･Jun Muto･Taishi Kamatani･Yahiro Honda･Daiki Yamaguchi (Toyota Motor)

With the enhancement of functionalities in automotive electronic components and the diversification of vehicle designs and applications, the thermal design of electronic components based on their installation positions has become increasingly critical. To predict the temperature within the cabin, this paper applies the method proposed in our first report to a different vehicle model and region, and compares the results with measurements to validate the boundary conditions under which the method is effective and to improve errors in predicted temperature variations.

Investigation of a Vehicle Aerodynamic Prediction Model Using Latent Representations with Separated Global and Local Geometric Features

Takuji Nakashima･Taichi Okamoto･Jiangdong Miao･Chisato Sasaki･Bisser Raytchev･Takahide Nouzawa (Hiroshima University)･Keigo Shimizu･Yusuke Nakamura･Kohei Seo (Mazda)･Makoto Tsubokura (Kobe University/RIKEN)

In this study, a latent representation of vehicle geometry is constructed by separating the shape into global structure and local features based on spatial resolution and integrating the resulting representations to better retain features associated with local geometric details. Based on this latent representation, an aerodynamic performance prediction model and a neural-operator-based model for high-resolution prediction of the flow field around a vehicle are constructed, and their effectiveness is examined.

Transfer Learning for Efficient Prediction of Automotive Surface Pressure and Stress Using Graph Neural Networks

Tokiya Tanaka (Kobe University)･Junya Onishi (RIKEN Center)･Takuji Nakashima (Hiroshima University)･Makoto Tsubokura (Kobe University)

To improve the efficiency of automotive aerodynamic performance evaluation, GNN-based models that directly predict pressure and stress fields on vehicle surfaces have attracted considerable attention. However, scratch learning for each vehicle type requires costly CFD data generation and model training. In this study, transfer learning using a pretrained model is applied, and its effectiveness is evaluated in terms of training time and prediction accuracy.

Development of a prediction method for leakage noise through door gaps using CAE

Tatsuya Toki･Yuta Ito (Toyota Motor)･Fumihiko Kosaka (Dassault Systemes)･Shiro Yasuoka (Toyota Motor)

Leakage noise, a type of aerodynamic noise, occurs when sound passes through small gaps such as door clearances during high-speed driving and is a key factor in cabin quietness. This study develops a CAE-based prediction method and applies it to a door structure to estimate sound transmission paths and levels into the cabin under acoustic excitation. The predicted results are validated through comparison with experimental measurements conducted under similar conditions, demonstrating the effectiveness of the proposed approach.

Fundamental Study on Inferring Aerodynamic Characteristics by Large Language Models Using Latent Representations of 3D Shapes

Satoru Ito (Nagoya University)･Koji Nishiguchi (RIKEN)･Koichiro Nakaya･Yuuri Ozaki (Nagoya University)･Hiromune Kanamori･Shingo Noritake･Hiroshi Tanaka (Toyota Systems)

To integrate Large Language Models (LLMs) into the automotive aerodynamic design process, it is essential to accurately capture complex, non-linear geometric features. This study proposes an approach that compresses 3D car shapes into latent vectors using DeepSDF and directly inputs them into an LLM to predict drag coefficients (CD). Specifically, we investigate the effect of expanding the dimensionality of the latent vectors on the inference accuracy. Results using the DrivAerNet++ dataset demonstrate that increasing the dimensionality enhances the LLM's physical inference capability, significantly reducing the prediction error without compromising geometric reconstruction accuracy.

Consideration for High-Accuracy 6-DOF Vibration Contribution Analysis Method utilizing Operational TPA and Virtual Point Transformation

Koki Fujimaki･Kenta Hara･Junji Yoshida (Osaka Institute of Technology)

In this study, we considered 6-DOF contribution separation analysis method from the excitation source, where direct measurement is difficult, to the response point by combining Virtual Point Transformation (VPT) and operational TPA. In addition, we attempted to improve the accuracy of contribution separation by the modification of the VPT matrix. The method was applied to a simplified vehicle model and the accuracy was verified.

EXTRACTION OF HIGH CONTRIBUTING ACOUSTIC MODES OF VEHICLE LUGGAGE COMPARTMENT AND RESPONSE LEVEL ESTIMATION UTILIZING OPERATIONAL TPA-CAE COMBINED PROCEDURE

Junji Yoshida･Masato Nakamura (Osaka Institute of Technology)･Norihisa Nakajima･Ichiro Fukumoto (Kasai Kogyo)

In this study, a method for obtaining high contributing acoustic mode in a vehicle luggage compartment model to the response sound pressure at the rear seat position was proposed by combining CAE eigenvalue analysis and OTPA principal component model. In addition, a response point SPL estimation procedure after the luggage space modification was also considered by introducing principal CAE acoustic mode response into the TPA model at around the target frequency band.

Study on Health Monitoring of Road Infrastructure Using Tires Mounted with Microphones

Hiroshi Tani･Renguo Lu･Shinji Koganezawa (Kansai University)

We investigated a method for monitoring road surface conditions—such as surface roughness and unevenness—and the structural integrity of bridge decks, including their state of deterioration, using tires equipped with microphones. The results indicated that this method has the potential to detect surface roughness, unevenness, and the extent of bridge deterioration.

Measurement of Instantaneous Structural Intensity in Shell Structures Based on Moving Least Squares

Hironori Yamada (SUBARU)･Keisuke Abe (University of Michigan/North American SUBARU)･Toru Yamazaki (Kanagawa University)

A measurement method for instantaneous structural intensity in shell structures was developed to visualize the active component of vibrational energy flow during transient wave propagation. Vibration velocities measured at multiple points using a scanning laser Doppler vibrometer were processed using moving least squares (MLS) to reconstruct the displacement field and its spatial derivatives on the shell surface. The instantaneous structural intensity was then evaluated from the reconstructed field. The proposed method was validated by comparing experimental with FEM.

Evaluation of the dynamic characteristics of the human body-seat system and ride comfort using actual vehicle vibration

Takuya Yoshimura･Kouji Ogasawara･Gen Tamaoki (Tokyo Metropolitan University)･Shuya Nojima･Hirotaka Shiozaki (Mitsubishi Motors)

The six-axis actuator reproduce the floor vibration when the car running in an actual road. The principal modes of car seats are analyzed and compared with respect to two kinds of seats at several different speed of the car. The principal modes that have significant effects to the ride comfort are investigated.

Development of Comfortable Operating Sound for Power Seat (Part 1)
-Optimization of Gear Meshing Force for Reducing Power Seat Operational Noise-

Keiichiro Shinbori･Atsushi Ssto･Rui Tokida (Toyota Boshoku)

With the rapid electrification of vehicles, the demand for reducing cabin noise has increased. In this study, attention was focused on the gear meshing excitation force of the motor in power seat systems. A 1D-CAE model was developed, and optimization analysis was conducted to evaluate the reduction effect of the excitation force. The effectiveness of the proposed method for application in the early design stage was also demonstrated.

Development of a Prediction Method for Ventilation Noise Reduction in Air-Cooled Battery Units (Prediction of Duct Attenuation)

Fumihiro Chatani･Takuo Watanabe･Masanobu Nishiwaki･Akira Ohtagaki (Toyota Motor)

Blower-induced ventilation noise is a key issue in the development of cooling performance for HEV battery packs. This study develops a prediction method focused on sound attenuation in duct sections (“duct attenuation”). Using the duct system of a production vehicle, the effects of sound-absorbing materials and duct bends on attenuation characteristics were verified.

Boundary Layer Control and Flow-induced Noise Reduction in Duct Bends Using Surface Microstructures

Shunpei Nomura･Sobue Yuta (Gifu University)･Sho Kosaka･Kenji Yoshida･Kaori Seki (DENSO)･Yasuhiko Sakai (Nagoya Industrial Science Research Institute)･Shuho Yamada (Toyama Prefectural University)･Osamu Terashima (Gifu University)

This study experimentally investigates the effects of boundary layer control using surface microstructures smaller than 1 mm on flow-induced noise and pressure loss in separated and reattached flows occurring in bends of ventilation and air-duct systems. The results reveal that optimizing the characteristics and geometry of the microstructures enables reduction of flow-induced noise in specific frequency bands without increasing pressure loss.

An Item Response Theory-Based Classification of Hazards in a Driving Risk Assessment Test

Kazumitsu Shinohara･Naoko Masuda (The University of Osaka)･Kan Shimazaki (Kindai University)･Rin Itoh･Hirofumi Aoki (Nagoya University)

The driving risk assessment test evaluated in this study requires participants to observe computer graphics (CG) first-person driving videos and sequentially touch detected hazards within each scene. To improve evaluation accuracy, it is desirable to assess hazard perception skills while accounting for the unique characteristics of each individual hazard presented during the test. This study aims to clarify the factor structure underlying hazard perception abilities within this assessment framework and attempts to estimate the item characteristic parameters of each hazard utilizing item response theory (IRT).

Characteristic Analysis of Vehicle-VRUs Crashes Based on Real Accident Data in China

ze yao Li (Huaqiao University)･Zhuo Li･Di Pan (Xiamen University of Technology)･Koji Mizuno (Nagoya University)･Yong Han (Xiamen University of Technology)

Vulnerable Road Users (VRUs) suffer high casualty rates in traffic crashes and are a major focus of road safety research. Based on 4,060 real vehicle-VRU crash videos from the VRU-TRAVi database in China, this study conducts statistical and characteristic analysis across pre-crash, in-crash, and post-crash stages. K-modes clustering is used to identify typical accident scenarios. The findings reveal spatiotemporal, kinematic, and injury patterns of pedestrians, cyclists, and powered two-wheelers, and clarify key risk factors including visual obstructions, speed, and impact locations. Results provide reliable data support for vehicle safety design, road management, and VRU crash prevention.

Study on Strength Prediction of 6000 Series Aluminum Alloys Using Machine Learning and its Application to Crash Simulation (Second Report)

Junya Nagai･Kentarou Aono･Ryousuke Negawa･Hiroki Takami (SUBARU)

The purpose of this research is to use machine learning to predict the strength of an actual vehicle after 6000 series aluminum alloy, which has age-hardening characteristics, has hardened due to heat during the paint baking process, and to apply this to a crash simulation to improve the accuracy of performance predictions by making the model more accurate to the actual vehicle.

Theoretical Evaluation of μ Measurement with Icy Road using Backscattered Light

Tomoki Kawahara･Akihiro Kido (Tohoku Gakuin University)

In the measurement of the friction coefficient (μ) of icy road surfaces using NIR backscattered images, multilayer reflections composed of reflections from both the ice surface and the underlying road surface layer are measured. In particular, the reflected light from the road surface layer is considered to depend on both the measurement wavelength and the surface roughness. In this study, these reflection characteristics were investigated, and the validity of measuring the friction coefficient (μ) of icy road surfaces using backscattered light was theoretically verified.

Modeling and Reproducibility Verification of Vehicle Rollover Behavior Induced by Entry into Gravel

Hiroki Ihara (SUBARU)･Toshihiko Kozai･Tsutomu Iwase (Gunma University/SUBARU)･Naoki Morotomi (SUBARU Techno)･Hirofumi Kinoshita･Seiichi Gokurakuji (SUBARU)

In real-world traffic environments, vehicles may skid into roadside sand or gravel, potentially leading to rollover accidents. Focusing on this gravel entry, we modeled the gravel and identified the friction coefficient between gravel particles. Furthermore, we verified the reproducibility of vehicle behavior using the developed gravel model. This paper reports on these results.

Remote Connection Demonstration for Cycling and Driving Simulators and the Impact of Latency on Decision-Making

Takuma Yamaguchi･Masayasu Harimoto･Kazunori Ban (Toyota Technical Development)

Since traffic behavior involves coordinating with others to move smoothly, linking multiple traffic simulators is a useful method for analyzing traffic behavior. However, such linking requires network communication, making latency a significant challenge. Therefore, we will demonstrate remote connections and verify the resulting latency. Furthermore, by utilizing a decision-making model, we will assess the acceptable level of latency.

Quantitative Evaluation of Safe Driving Behaviors and Their Limitations for Autonomous Vehicles in Car-to-Bicycle Crossing Scenarios
-First Report: Near-Miss-Based Risk Assessment-

Masami Aga (Tokyo University of Agriculture and Technology)･Yuichi Saito (University of Tsukuba)･Pongsathorn Raksincharoensak･Masao Nagai (Tokyo University of Agriculture and Technology)

This study analyzes 483 car-to-bicycle near miss cases and reconstructs them into collision scenarios to evaluate autonomous driving vehicle safety. The results quantitatively show that even when driving at the legal speed limit, about 43% of scenarios remain unavoidable. Preemptive deceleration can reduce collision risk; however, even with a 10 km/h reduction, 16% of cases still result in a collision, and with a 20 km/h reduction, 2% remain unavoidable. The study establishes a data driven framework for assessing safe driving behavior and clarifying both the benefits and the practical limits of autonomous driving vehicle performance.

An Evaluation of the Acceptance of a Driver Assistance System That Alerts Drivers to the Presence of Bicycles

Asuka Harada･Hitoshi Kanamori (Nagoya University)･Kenichi Yamada･Hayato Mizuma･Masaharu Saito (Toyota Motor)･Yuki Yoshihara･Nihan Karatas･Linjing Jiang･Takahiro Tanaka (Nagoya University)

Communication-based driver assistance systems, particularly V2X-based technology, are expected to prevent crossing collisions on residential roads. However, challenges remain regarding the accurately of notifications alerting drivers to the presence of bicycles. We identified the issues associated with low correct notification frequencies and narrowed down the notification methods suitable for low-frequency notifications. We conducted driving simulator (DS) experiments under various conditions, including correct notifications, false notifications, and missed notifications, to assess the acceptability of the assistance system. We also investigated the impact of low-frequency assistance systems on driver attention and report our findings here.

Effects of Viewpoint Position on Steering Characteristics in Remote Operation of Autonomous Buses

Yusaku Matsumura･Naoki Furugohri･Toshiyuki Sugimachi･Toshiaki Sakurai･Shuichi Yahagi (Tokyo City University)･Masaaki Onuki･Kimihiko Nakano (The University of Tokyo)･Jongseong Gwak (Takushoku University)

This study evaluated the impact of different viewpoint positions on driving characteristics in the remote operation of autonomous buses. Using a driving simulator for heavy-duty vehicles, we established various viewpoints and speed conditions. By conducting a comparative evaluation of driving performance and workload, we examined the optimal viewpoint conditions for remote operation.

Online Map Generation Using Stereo Cameras: A Case Study

Ryo Yanase･Langxing Tan･Akitaka Okou (SUBARU)

Accurate map generation is a key challenge in autonomous driving and advanced driver assistance systems (ADAS). This paper proposes a method for online map generation using object recognition results from stereo cameras. The proposed framework integrates observed object information in real time, supporting robust map generation that can adapt to dynamic changes in the environment. In addition, we validate the effectiveness and practicality of the proposed method through experiments using real-world driving data.

Development of a High-Power Density Motor
-(Fourth Report)-

Naoki Itasaka･Michiharu Kawano･Hisayuki Kabashima･Kentaro Nomura･Kazunori Hirabayashi (MCF Electric Drive)

Based on issues identified in previous studies, this paper presents design improvements for a high power density motor. High-speed operation, electromagnetic optimization, and cooling enhancement were applied. Design conditions considering mechanical strength and loss were clarified, and electromagnetic and thermal characteristics were improved through redesign of flux, current distribution, and cooling paths. Analytical methods evaluated the influence of each factor on power density. Prototype testing confirmed that power density exceeded 10 kW/kg, demonstrating the effectiveness of the proposed design approach.

Development of a High-Power Density Motor
-(Fifth Report)-

Hisayuki Kabashima･Naoki Itasaka･Michiharu Kawano･Kentaro Nomura･Kazunori Hirabayashi (MCF Electric Drive)

This paper presents a detailed evaluation of the prototype motor designed in Paper 4. Output characteristics, efficiency, temperature distribution, and loss behavior at high-speed operation were investigated. Comparison with analytical results enabled quantitative evaluation of the contributions of electromagnetic design and cooling structure. In addition, interactions among design factors were analyzed to identify dominant factors governing performance. Finally, design constraints and remaining challenges were clarified, providing insights for further improvement of high power density motor design.

Development of Miniaturization, High Efficiency, and High Torque Density Technologies in e-Axle

Yohei Takahashi･Katsura Uesugi･Takahiko Oishi･Eiichi Shiomitsu (Meidensha)

A compact e-Axle with a low-profile, lightweight structure and high torque density was developed for mini and A-segment vehicles. The gear train adopts a two-shaft parallel configuration, and the inverter is arranged in the vacant space alongside the motor to minimize the unit dimensions in all three directions. High torque density was achieved by increasing the motor winding fill factor and employing a dual-V magnet configuration, while high efficiency was attained by increasing the switching speed and reducing oil losses.

Development of an Abnormality Detection and Recovery Method for Position Sensorless Control of a Generator Motor

Kenichi Mori･Tetsurou Kojima･Akira Sawada･Takashi Nakajima (Nissan Motor)

When applying position sensorless control to a generator motor in a 100% electric-drive hybrid vehicle, handling transient estimation abnormalities is an important issue. This study proposes an abnormality detection method based on the rate of change of estimated speed and current, along with a recovery method combining gate-off and three-phase short-circuit control. The method achieves both overcurrent suppression and vibration reduction while enabling restart. Its effectiveness is verified through vehicle experiments.

Basic Verification of Hybrid-Excitation Memory Motor with Field Winding Connected Between Neutral Points of Dual Three-Phase Windings
-(Part 4)-

Hiroaki Makino･Ryosuke Saito･Makoto Matsushita･Katsutoku Takeuchi (Toshiba)

Variable flux technology has attracted attention as a means of improving motor efficiency. The authors propose a hybrid-excitation memory motor with field winding connected between neutral points of dual three-phase windings, aiming to achieve superior variable flux performance while suppressing an increase in inverter capacity. This paper presents the results of verifying the efficiency improvement effect using a miniaturized prototype model.

Development of high-speed prediction system using surrogate models for motor cooling CAE

Shintaro Nakano (Toyota Motor)

This paper proposes a method for accelerating particle-based motor cooling CAE using a surrogate model. The method consists of a preprocessing step that converts CAE results to a Cartesian grid, followed by prediction of particle behavior using a geodesic convolutional neural network (GCNN) and subsequent calculation of the wetted area. The results show that the computation time is reduced to approximately one minute compared with conventional particle-based analysis, while achieving a wetted-area prediction accuracy with a mean absolute percentage error (MAPE) of 5%.

Development of a Model-Based 2-Stage Motor System Inverter Durability Test Mode Reflecting Customer Usage

Minsu Hyun･Miyong Lee･Je Hwan Lee･Yeong Ju Koh (Hyundai Motor)

This study proposes a methodology for developing durability test profiles for a 2-stage motor system inverter based on real-world customer usage. A C-segment electric crossover vehicle was used as a reference to generate simulation scenarios, and a multi-physical vehicle model was applied to reproduce operating conditions. The generated scenarios were applied to a target vehicle to calculate inverter thermal loads, and an optimization approach was used to derive durability test profiles. The proposed method reproduced customer usage within a 5% error margin and established durability test profiles applicable to component-level inverter durability testing.

Research on integrated charging and Power supply system for electric vehicle

Keisuke Azusawa･Yoshihisa Kubota･Soumei Nakatomi･Kiyoshi Asami･Keiya Nimura･Takumi Todoroki･Naoya Naito (Honda R&D)

As electric vehicles incorporate a large number of electrical components, there is a growing demand for miniaturization, cost reduction, and high efficiency. In this study, an integrated charging and power supply drive unit utilizing a traction motor and inverter is investigated. By switching the motor windings between series and parallel configurations, both high power and high-efficiency drive operation are achieved. Furthermore, torque-free operation during AC charging and high charging efficiency are simultaneously realized.

Development of a BEV System for Toyota's New Mid-Size Pickup Truck

Hayato Suzuki･Kengo Maeda･Takeshi Hashimoto･Koichi/ Nakamura･Hiromitsu Kawamori (Toyota Motor)

Toyota is promoting a multi-pathway strategy to achieve carbon neutrality by addressing increasingly stringent fuel economy and emissions regulations while delivering attractive vehicles that exceed customer expectations. As part of this approach, this study presents the development of a battery electric vehicle (BEV) powertrain system for a mid-size pickup truck, which plays a vital role in supporting society, particularly in commercial applications. The developed system is designed to provide off-road driving capability.

Development of the Third Generation 100% Electric Drive Hybrid Powertrain for Compact SUV

Hironari Kiriseko･Atsushi Kobayashi (Nissan Motor)

The third-generation 100% electric-drive hybrid powertrain (e-POWER) has been developed for compact SUV. This third-generation hybrid powertrain delivers top-level quietness and acceleration performance, along with high fuel efficiency.

Development of battery technology for powerful driving of premium minivans

Satoshi Murakami･Takashi Honda･Ryo Sakamoto･Kenji Hosaka･Shozo Ishimoto･Norihiko Hirata (Nissan Motor)･Tatsuhiko Kawasaki･Kiyoharu Hosoya･Eiji Seki (Vehicle Energy Japan)

Nissan has introduced 100% electric drive hybrid systems from small cars to minivans. To meet the need for high-output batteries for use in large minivans, we developed a new battery cell and designed a balance between heat generation and cooling performance to realize a high-output battery system that balances cost, weight, and durability.

Development of the Third Generation 100% Electric Drive Hybrid Powertrain for Large Minivan

Shinichi Suzuki･Naohiro Yoshida･Shin Ishizaki (Nissan Motor)

The new large minivan was developed with the aim of achieving a high-level balance between driving pleasure and passenger comfort. By improving fuel efficiency and quietness through the third-generation 100% electric drive hybrid powertrain (e-POWER) and by adopting new technologies to accommodate larger vehicle sizes, it delivers excellent driving performance, comfort, and fuel efficiency.

A Study on Control Calibration Optimization in THS Engine Start-up Vibration by Applying MBSE

Soh Shimizu･Masaki Sagawa･ ･ ･ ･ (Toyota Motor)

In recent vehicle dynamic performance development, increasing complexity has led to significant growth in control calibration effort and rework. This study targets engine start-up vibration in hybrid vehicles and constructs a SysML-based model. By visualizing relationships among requirements and design elements, and introducing validation based on intermediate state variables, a principled calibration approach is achieved. The proposed process demonstrates effectiveness in reducing rework and calibration effort while supporting an efficient development flow from performance planning to hardware validation.

Improving e-Axle System Development Efficiency through MBSE and Generative AI (LLM)
-(Part II)-

Takurou Hirano･Masaru Katsuki･Kazunori Kawashima･Takurou Kawasumi (JATCO)･Daiki Katagiri･Makoto Morinaga･Motokazu Nishimura (Stockmark)

In our previous report, we presented the efficiency improvement of e-Axle development by converting MBSE models into knowledge graphs and utilizing generative AI. However, a remaining challenge in maintaining the knowledge graph is the need for continuous updates. In this presentation, we propose a methodology and provide practical examples of continuously updating the graph by using AI to automatically extract information structures from unstructured documents, such as technical reports.

Investigation of Risk Assessment Methodology for Physical Layer Attacks to Prevent Vehicle Theft

Maki Shimokawa･Takanori Miyoshi･Kazuhiro Kakito･Satoshi Horihata (Sumitomo Electric Industries)

ISO/SAE 21434 risk assessments tend to underestimate physical layer attack risks. To address growing physical threats like vehicle theft, this paper proposes a risk assessment methodology for automobiles that explicitly incorporates physical-layer considerations. Furthermore, we discuss the importance of physical-layer security alongside software countermeasures to achieve early attack detection.

Bayesian Approach for Unknown Risk Quantification on Highly Automated Driving

Masanori Yokota (NTT Data Automobiligence Research Center)

In highly automated driving, it is difficult to identify all contexts and triggering conditions in advance. Therefore, in safety arguments, it is necessary to appropriately estimate the risks arising from unknown contexts and triggering conditions and evaluate whether they meet acceptable levels. This presentation will introduce a method for evaluating unknown risks using a Bayesian approach, through concrete examples.

A Re-certification Credit Allocation Method for OTA Software Updates in Software-Defined Vehicles

Naoki Hashimoto (Monstarlab)

Over-the-air (OTA) software updates can alter type-approval-relevant functions of software-defined vehicles, yet how much of the required re-assessment can be discharged virtually rather than physically remains under-specified. Simulation-credibility provisions for type approval (EU 2022/1426; NATM) and software-update management (UN-R156/SUMS, RXSWIN) exist separately, but no method connects them by accounting for virtual evidence reuse across an OTA change. This study proposes such a credit-allocation method, pairing change-impact classification with a virtual-evidence credibility tier, and demonstrates it on the OTA-delivered ODD speed extension of a deployed L3 ALKS (UN-R157).

Regulatory Frameworks for RXSWIN and Software Update, A Comparative Overview between Japan and EU

Megumi Enomoto･Tetsuya Niikuni (NALTEC)

Post-production vehicles can have their original functions extended or modified by software updates following the establishment of UN-R156 in 2021. Methods for verifying regulatory compliance of those modified vehicles are different between Japan and the EU; the EU approach specifically compares the RXSWIN of the vehicle and its certification. This study comprehensively outlines the contents and the background of the 2025 UN-R156-01 amendments, and provides an analysis of operational challenges of software updates using RXSWIN.

Relationship between Online Driving Aptitude Assessment and On-Road Driving Evaluation for Older Drivers
-Study on Driver Characteristics for Delaying Driving Cessation (49)-

Rin Ito･Shunji Taniguchi･Hirohumi Aoki (Nagoya University)

This study examined the relationship between on-road driving evaluation and various indicators, such as grip strength, TMT, MVT, and HP, obtained from an online driving aptitude assessment for older drivers. While acknowledging certain limitations, we demonstrate its potential as a simplified assessment method that encourages drivers to undergo driving aptitude tests.

Preliminary Studies to Measure Cognitive Characteristics of Elderly Drivers, Utilizing Multitasking Conditions That Simulate Driving in a Simplified Manner
-Study on Driver Characteristics for Delaying Driving Cessation (50)-

Hiroshi Kishi･Hirofumi Aoki (Nagoya University)

To provide driving assistance that is precisely tailored to each individual’s needs, it is also important to understand the driving cognitive characteristics of each elderly driver. We are currently developing an app to measure cognitive characteristics -including “change detection in peripheral vision,” “spatial search,” “decision-making,” and “spatial memory”-under multitasking conditions that simulate driving in a simplified manner. Preliminary findings have demonstrated the usefulness of these multitasking conditions.

Study of Driving Error Mechanisms by Inadequate Steering-Pedal Coordination

Yui Kato･Machiko Hiramatsu･Yuka Nakayama･Akihiko Ebina (Nissan Motor)･Naoto Kamide･Masataka Ando (Kitasato University)･Atsushi Takamatsu (Nissan Motor)

This study aimed to clarify the driving error mechanisms that are common among older drivers. We analyzed crashes and near-miss incidents involving lane departure or pedal misapplication. The results suggested that one contributing factor is inadequate timing and magnitude of coordination between steering and pedal inputs during turning. Based on these cases, we developed an operating task that quantitatively measures this coordination. We examined how task performance relates to drivers’ physical and cognitive functions. From these data, we identified individual characteristics and typical patterns of steering and pedal actions associated with difficulties in coordinating these controls.

Effects of Early Cataract on Driving Behavior in Low-Light Conditions

Machiko Hiramatsu･Tsutomu Kawano･Yuki Ito･Yuki Hayakawa･Atsushi Takamatsu (Nissan Motor)･Takushi Kawamorita (Kitasato University)

Cataract is prevalent among older adults, reducing visual acuity under low-contrast and glare conditions, and has been associated with traffic accidents. This study aimed to clarify the effects of cataract on driving by measuring driving and gaze behaviors under dusk and nighttime conditions using a driving simulator, and by analyzing their relationship with lens opacity. Drivers with lens opacity exhibited compensatory behavior during right turns and showed delayed recognition of destination signs. These findings suggest that cataract-related changes may affect driving safety under low-contrast conditions.

Optimization of Fuel Injection Control Based on Combustion Chamber Wall Temperature Estimation for Improved Fuel Economy and Reduced Emissions

Ryutaro Morioka･Ryo Adachi･Takeshi Tsuda･Susumu Shimura･Kotaro Atsushi (SUBARU)

In hybrid vehicles that restart the engine frequently, the engine condition changes a lot at restart, which affects emissions and fuel economy. In this study, vehicle tests were conducted using an engine equipped with a wall temperature sensor, confirming fuel injection reduction during restarts. In addition, an AI model was developed to estimate wall temperature from existing control parameters, showing the potential of wall-temperature-based injection control.

Proposal of numerical methods for computationally affordable and high-fidelity large eddy simulation of automotive engines

Hiroki Yao (Ryoyu Systems)･Takayuki Ito (JARI)･Toru Takabayashi (Honda R&D)

As the circumstances surrounding the development of automotive internal combustion engines have become increasingly complex, there is a growing need to reduce the cost of CFD simulations, one of the key analysis tools, and to improve its prediction accuracy. In response to this demand, the authors have been developing a CFD code that employs cell-based AMR and high-order discretization methods. This paper presents the progress of these efforts, along with demonstrative computational examples.

A Fundamental Study on the Geometry of Intake Manifolds for Multi-Cylinder Engines with a Single Throttle System
-Evaluation of Intake Air Distribution Characteristics Using Transient Flow Analysis-

Takumu Takayama･Kenshin Koshimizu･Shinobu Kasamatsu･Wenbao Wu (Tokai University)･Kazuki Ogawa (Aichi University of Technology)･Takayoshi Narita･Hideaki Kato (Tokai University)

The authors are conducting ongoing research into improving the performance of multi-cylinder gasoline engines suitable for small-scale racing vehicles. This report presents a fundamental study on the effects of intake manifold geometry on air mass distribution characteristics, focusing on the flow pattern from the intake port—equipped with an air restrictor—to the cylinders, and utilizing unsteady fluid dynamics analysis to evaluate these geometries.

Experimental Analysis of Unburned Hydrocarbon Emissions in Lean-Burn Spark-Ignition Engines

Shoya Kawaguchi･Tatsuya Kuboyama･Yasuo Moriyoshi (Chiba University)

Incomplete combustion and associated unburned hydrocarbon (UHC) emissions remain critical challenges limiting the application of lean-burn combustion as a high-efficiency engine operating strategy. In this study, combustion characteristics and UHC formation and emission behavior were investigated under lean-burn conditions using an exhaust gas analysis system equipped with Fast FID and NDIR, together with heat flux sensors. The dominant factors governing exhaust UHC emissions were identified.

Development of High Thermal Efficiency PFI Lean-Burn Engine (1st report)

Kazunari Watanabe･Yukihide Nagano･Hiroaki Masatsuki･Kazuhito Okui･Keiichi Sata･Kousuke Kusaba･Akishige Sakuragi･Yuuta Shima･Kazuya Naitou･Tatsuya Ehara (Daihatsu Motor)

We have been developing a high-quality, affordably priced port fuel-injection (PFI) lean-burn gasoline engine for compact vehicles (λ ≥ 2). Modifications to the combustion-chamber geometry improved in-cylinder flow, enhancing flame speed and combustion stability, and extending the lean limit to λ = 3. In the low-to-mid engine speed range, the engine achieved indicated thermal efficiency exceeding 45% and low NOx emissions.

Investigation of a Combined ORC-TEG Waste Heat Recovery System for a Hybrid Electric Vehicle with a Lean-Burn SI Engine

Masaki Naruke･Takaaki Kitamura (JARI)

Recovering waste heat is essential for improving the fuel efficiency of hybrid electric vehicles. In this study, a waste heat recovery system combining an organic Rankine cycle (ORC), including engine cooling, and a thermoelectric generator (TEG) is applied to a hybrid electric vehicle equipped with a lean-burn spark-ignition engine capable of operating at an excess air ratio of 2.0 or higher. The performance of the combined ORC-TEG system is evaluated using one-dimensional numerical simulations.

Navigation under Rank-Deficient Localization for Nonholonomic Ground Vehicle
-A Special Spiral Curve Method-

Wei Wang･Kimihiko Nakano (The University of Tokyo)

This study proposes a vehicle navigation method using special spiral curves for rank-deficient localization, where only lateral position feedback is available. The proposed approach enables accurate navigation without odometer-based positioning and avoids curvature breakpoints. Experimental results demonstrate the feasibility of navigation under sensor-limited conditions and show that the method is potential to reduce path deviation.

Design and Development of a Photorealistic Simulation Platform for Model-Based Development of End-to-End Autonomous Driving

Keigo Nakamura･Miyu Yokoyama (Aisin)

CG-based autonomous driving simulation faces challenges such as domain gaps with real-world imagery and high modeling costs. To address these issues, this study proposes a simulation platform that jointly simulates 3D Gaussian Splatting and vehicle dynamics. By tightly integrating photorealistic scene representation with physically consistent vehicle motion, the proposed approach achieves both visual realism and motion accuracy. The platform is evaluated through experiments, confirming its effectiveness for model-based development (MBD) of autonomous driving systems.

Evaluating Occluded Pedestrian Detection and Enhancing Distant Recognition via Virtual Telephoto Cameras in Autonomous Driving

Yitong Wang･Jishu Miao･Yukiya Hattori･Tsubasa Hirakawa･Takayoshi Yamashita･Hironobu Fujiyoshi (Chubu University)

To enhance the safety of autonomous driving and improve the detection accuracy for distant objects, we propose a Multi-View BEVFormer that combines conventional camera views with a view focused specifically on distant regions. By evaluating the effectiveness of this proposed method, we demonstrated that it achieves highly accurate detection of objects 100 meters away, which are traditionally difficult to detect using conventional approaches.

Application of High-Precision LiDAR Recognition and Automated Inspection for the Introduction of Infrastructure-based Autonomous Driving Systems into Vehicle Inspection Factory

Shinya Hozumi･Takeshi Kanou･Yuki Okamoto･Yuhei Nagafuchi･Kento Iwahori･Noritsugu Iwazaki･Takuro Sawano･Yuta Kishioka (Toyota Motor)･Seiya Takata･Kenta Azuma (DENSO)

To address the challenges of labor shortages and to enhance productivity in vehicle manufacturing plants, we are developing an infrastructure-based autonomous driving system. In environments where humans and equipment coexist, and under conditions with external disturbances, we have developed self-localization and object detection functions based on high-precision LiDAR, replacing conventional camera-based approaches. Furthermore, we are investigating the feasibility of automated inspection enabled by more precise vehicle control.

Active Misalignment Correction System for Autonomous Driving Radar Using IMU/MAG Sensors and Actuators

Sukbom Son (Hyundai Motor)･Juhwan Park･Wanho Son (Ecoplastic)･Jin Young Yoon･Dongha Kim･Hongheui Lee･Sungho Park･Soobok Kim (Hyundai Motor)

Automotive radar sensors are a critical component of Advanced Driver Assistance Systems (ADAS), and their misalignment directly compromises autonomous driving safety. When integrated into the bumper rather than the front-end module (FEM), angular deviations are difficult to manually correct due to restricted physical access, and the exposed position makes the sensor inherently susceptible to impact-induced misalignment. In this study, we propose an automatic self-leveling system that detects radar misalignment via IMU and magnetometer (MAG) sensors and physically corrects the deviation using a custom-designed 2-DOF actuator, eliminating the need for manual calibration.

Tightly Coupled LiDAR-IMU-Odometry Fusion with Continuous-Time Trajectory Representation for Robust Ego-Vehicle Localization

Naoki Akai･Yasuhiro Akagi･Takayuki Morikawa (Nagoya University)

LIO can be used with only a LiDAR and an IMU, while odometry, which represents vehicle motion characteristics, is effective for improving robustness in vehicle applications. This presentation describes a robust vehicle localization technique that extends conventional discrete-time state estimation systems to continuous-time state estimation systems, enabling seamless fusion of LiDAR, IMU, and odometry according to their respective characteristics.

Development of Autonomous Driving with a Bird's Eye View Perception System Integrated with Map Information of Road Structure and Connectivity

Kento Kubota･Hajime Oyama･Kazuki Ishii･Kaito Sakogawa･Hideyuki Takao (SUBARU)

We developed a surrounding vehicle sensing system for autonomous driving that integrates Bird’s Eye View perception with road structure and connectivity. Surrounding vehicles detected by the perception are matched onto a map, and their future behavior are estimated by considering road structure and connectivity. This system enables autonomous vehicles to operate in coordination with surrounding vehicles based on their behavior prediction.

An Integrated Framework for Predicting Vehicle-to-Vehicle Interactions and Planning Based on GameFormer

Masaya Miwa･Akira Ito (Aichi Institute of Technology)･Ken Kinjo (DENSO)

In autonomous driving, planning faces increased state dimensionality due to interactions among multiple traffic participants, making it difficult to handle with model-based methods alone. This study proposes a planning method that integrates GameFormer, which predicts future trajectories considering interactions among traffic participants from past trajectories and map information, with model-based planning.

Trajectory planning and deviation monitoring with combinatorial optimization in highway merging scenarios

Ryuji Takahashi (MIRISE Technologies)･Koji Oya (DENSO)･Kota Matsuura･Kenshin Yamamoto (MIRISE Technologies)

We have reported a trajectory planning method by using combinatorial optimization for vehicles merging from a local road onto a highway in various situations. In the previous spring conference, we showed a comparison between simulation and real-world data in highway merging scenarios. In this report, we incorporate a monitoring function into the previous method. We show that the function can reduce the number of the planning recalculations, and hence the computational cost is reduced.

Autonomous Merging System in Traffic Congestion with Dynamic Adjustment of Decision Thresholds

Takumi Iwasa･Hanwool Woo (Kogakuin University)

This study achieves autonomous merging for automated vehicles during traffic congestion by implementing a decision-making algorithm that accurately mimics human driving behavior. Utilizing a simulation environment constructed from empirical traffic flow data, the proposed system dynamically adjusts the specific thresholds required for merging maneuvers. These adjustments are continuously made in response to the real-time behaviors of mainline vehicles, including their travel speeds and inter-vehicular distances. By employing this dynamic adjustment mechanism, the system successfully enables flexible and adaptive merging decisions under dense traffic conditions, which are inherently difficult to achieve when relying solely on conventional, fixed decision thresholds.

Analysis and Modeling of Interactive Low-Speed Merging Behavior Using a Driving Simulator

Ren Kuroyanagi･Tatsuya Ishiguro･Hiroyuki Okuda･Tatsuya Suzuki (Nagoya University)

This study analyzes and models human driver behavior during low-speed right-angle merging from a parking area onto a main road. Based on observational experiments using a driving simulator, the study focuses on a slight forward movement behavior near the stop line, referred to as “Inching” and proposes an estimation model that represents human merging decisions as transitions among multiple states.

Evaluation of Visual Alerts on a Head-Up Display Considering Driving Experience

Hisato Fukuda (Gunma University)･Toshihiko Kozai･Tsutomu Iwase (Gunma University/SUBARU)･Ikuo Goto･Takeshi Torii･Tsukasa Mikuni (SUBARU)

The effects of visual alerts presented on a head-up display on drivers were evaluated. In particular, this study focused on driving experience to examine whether the effectiveness of these visual alerts varies at different levels of driver experience. A sensory evaluation experiment was conducted using a VR-based driving simulator to assess the effects of these alerts on participant groups with varying levels of driving experience. The experimental results revealed significant differences in both sensory evaluations and vehicle control performance across different presentation conditions and levels of driving experience.

Outdoor Evaluation Experiment Under Daytime and Nighttime Conditions on Perception of Automated Driving System Marker Lamps (Third Report)
-When Marker Lamps Are Installed Near Rear Signal Lamps-

Akihiro Abe･Yoko Kato･Tatsuya Iizuka･Michiaki Sekine･Yoshiro Aoki (NALTEC)

At WP.29, requirements for an "Automated Driving System (ADS) Marker Lamp," which indicates the status of automated driving, are currently under discussion. In this study, outdoor experiments were conducted under both daytime and nighttime conditions using an evaluation lamp with blue-green chromaticity developed based on the regulatory proposal submitted to GRE in 2025. The study focused on lighting conditions such as luminous intensity and luminous area to investigate the visual characteristics of the evaluation lamp and other vehicle signaling lamps, such as direction indicators and brake lamps.

Requirements For Easily Recognizable Icon Symbols

Yuka Miyashita (Nissan Motor)

Icon symbols on car switches and displays serve to communicate operation methods and meanings to the user. While many are easily understood without explanation, in order to design clearer icons for increasingly complex car functions, we considered them from a philosophical perspective, drawing inspiration from signs on public transportation and displays on home appliances and other devices.

Proposal of a quantitative evaluation method for response characteristics to visual and auditory stimuli in motorcycle forward collision warning HMIs

Takato Yamamoto･Keisuke Suzuki (Kagawa University)･Naotoshi Takemura･Joohyeong Lee･Tomoki Minami (Honda R&D)

This study proposes an evaluation methodology for motorcycle forward collision warning (FCW) HMIs that accounts for the unique riding environment. By replacing conventional driving simulator assessments with psychological experimental methods, we utilized a mental rotation task to apply individualized optimal cognitive loads. Under tightly controlled presentation conditions, we quantitatively measured 30 participants' reaction times to visual and auditory warnings across various downward viewing angles. The experiment successfully acquired robust data sufficient for statistical comparisons, yielding valid results consistent with existing knowledge. Ultimately, this establishes a methodological guideline for quantitatively evaluating motorcycle HMI cognitive characteristics.

Design Study of a Portable Driving Simulator through Co-design with Older Drivers

Linjing Jiang･Yuki Yoshihara･Nihan Karatas･Asuka Harada･Hitoshi Kanamori･Takahiro Tanaka (Nagoya University)

This study involved older drivers experiencing four types of portable driving simulators: a VR-based system with physical pedals, a physical-pedal system, a digital-pedal system, and a touch-operated system. Through group discussions, the advantages and limitations of each approach were identified. The redesign directions were then organized from the perspective of older drivers, considering the balance among acceptability, easy of operation, physical burden, and portability.

Maximization of Total Tangential Force Based on Rear-Front Driving Torque Distribution Control

Takane Akiyama･Yuki Yokokura･Kiyoshi Ohishi (Nagaoka University of Technology)･Jun-Ichi Fukui･Kenta Tatsuda･Yasumasa Imamura･Hirotaka Mochizuki (Mazda)

For both vehicle safety and operability, maintaining the vehicle's optimal total tangential force in response to the varying relationship between the tyre and the road surface is crucial. Particularly in All-Wheel-Drive (AWD) vehicles with independent front and rear drives, the flexibility of the front-rear drive force distribution ratio achieves this goal. This study investigates a drive-force distribution control method that maximises the sum of the tangential forces of the front and rear wheels, with the AWD vehicle as the control object.

Study on road friction information for next-generation road traffic safety
-Construction of new system to improve measurement procedures and accuracy-

Ichiro Kageyama (Consortium on Advanced Road-Friction Database)･Atsushi Watanabe･Yukiyo Kuriyagawa･Tetsunori Haraguchi (Nihon University)･Tetsuya Kaneko (Oosaka Sangyo University)･Minoru Nishio (Absolute)

Road friction information is crucial for ensuring the safety of autonomous driving and ADAS-equipped vehicles, and this information is considered essential, especially on snowy and icy roads in winter. In this study, we have been continuously measuring this road friction information, and we have now constructed a new measurement system to simplify the measurement procedure and improve measurement accuracy for wider-area measurements. This presentation will describe the overview of the system and provide examples of measurement results.

Estimation of Grip Margin and Road μ focusing on Motor Drive System Vibration

Eiichi Ono･Norio Yonezawa (Toyota Central R&D Labs.)･Tadakatsu Koyabu (DENSO)

The resonance phenomenon observed in wheel speed varies depending on the road surface friction condition. By utilizing this characteristic, it becomes possible to estimate the grip margin and the road surface friction coefficient (μ). In this paper, we propose an estimation method that makes use of the driveshaft resonance phenomenon in motor-driven vehicles. Furthermore, experimental verification of road surface μ estimation will be conducted on a proving ground where road surface μ is controlled.

Measurement of Three-Component Force Distribution in a Tire Contact Patch during Steering at Standstill Using Tread-Block Scanning

Tomonori Sakai (Honda R&D)･Masami Matsubara･Shuto Shimizu (Waseda University)

During steering at standstill, significant shear deformation occurs within the tire contact patch, resulting in a complex distribution of friction forces between the tread blocks and the road surface. In this study, we proposed a scanning measurement method capable of measuring contact forces at the tread block level, with the aim of elucidating the mechanical behavior within the tire contact patch during steering at standstill.

Loosening Progression of Wheel Nuts at Zero Axial Force

Takanobu Kawano･Ayako Okamoto･Yusuke Kimura (SOKEN)･Takahiro Tsuji･Yosuke Kimura (Toyota Motor)･Moe Suzuki (SOKEN)

The progression of loosening after the loss of clamping force in wheel fastening systems remains unclear, despite its importance for preventing tire detachment accidents. In this study, a tire test rig was used to measure the behavior of a nut under zero axial force conditions. The results indicate that an unloaded nut repeatedly contacts and separates from the wheel hole during tire rotation, thereby generating a force acting in the rotational direction of the nut, which may contribute to the progression of loosening.

Strength Properties of Steel/Aluminum Dissimilar Spot Welded Joint
-(Second Report) Investigation of Fatigue Strength-

Ayaka Kagami･Mitsuhiro Aimoto･Eisuke Umeno (Toyota Motor)･Hideaki Matsuoka･Tatsuyuki Amago (Toyota Central R&D Labs.)

In spot welding between steel plate and an aluminum alloy, it is well known that the intermetallic compound formed at the joint interface is closely related to the joint strength. In this study, we fabricated welded joints with protrusion-like structures to overcome the brittleness of intermetallic compounds in spot welding between steel plates and aluminum alloy sheet. We investigate the fatigue strength.

Coaxing Effect in Fatigue of a Stainless Steel Sheet with Stress Raiser

Gyoko Oh (Tokyo Roki)

We investigated the fatigue behavior of stress raisers in stainless steel sheets and clarified the influence of coaxing on the fatigue limit. By observing differences in crack initiation and propagation depending on the stress ratio R and stress amplitude from hysteresis loops and fatigue curves, we attempted to elucidate the mechanisms of crack propagation and fracture. The location and propagation rate of cracks differed depending on the stress amplitude and R value, and it was revealed that coaxing in stress raisers affects fatigue strength and is an important factor influencing crack arrest and fatigue life.

Additively Manufactured HEA for Functional Integration and Weight Reduction in Mobility Systems

Hyomoon Joo (Hyndai Motor)

Recent mobility systems require structural materials with stable properties over wide temperature ranges. Conventional alloys degrade under extreme conditions. A Ni-based high-entropy alloy was fabricated via additive manufacturing, enabling precise microstructural control. The alloy exhibited temperature-insensitive tensile behavior due to its stable single-phase structure and sluggish diffusion. Grain boundary engineering enhanced strain hardening and mechanical robustness. The material shows strong potential for automotive applications, including electric powertrain and thermal components, offering improved durability and reliability for next-generation mobility systems.

A Study on Optimization of Two stage rolling process to Improve formability and Reduce springback of Pure titanium thin sheet for Fuel cell Separator

Jaebong Park･Sunghwan Kim (Hyundai Motor)

It was confirmed to improve the formability and reduce springback of titanium for separators through a two-stage rolling process with intermediate annealing. The effect of rolling texture dispersion due to inducing twin was verified. In addition, the analysis of rolling texture, grain, mechanical properties and springback was conducted based on the number of rolling stage, thickness reduction ratio, final annealing temperature and time. Through these results, the optimal two-stage rolling process that can improve formability and reduce springback were derived.

Development of Forming Technology for Circumferentially Tailored Thickness Structures by Multi-Directional Forced Lubrication Hydroforming

Motoki Sasaki･Hiroki Tsutsumi･Yunosuke Asahina･Hiroaki Kubota (Tokai University)

Differential thickness structures with circumferential thickness distribution were formed using multi-directional forced lubrication hydroforming, and bending-compression behavior was evaluated through FEM analysis. Under three-directional and four-directional lubrication conditions, both the maximum load and absorbed energy were improved compared with conventional hydroforming. The results indicate that controlling the circumferential thickness distribution by forced lubrication can effectively enhance crash performance. Furthermore, the proposed method demonstrates the potential to achieve both lightweight structures and improved crash safety performance in automotive structural members.

Study on the Prediction Accuracy of Outer Panel Distortion Caused by Bead-Applied Stiffeners

Tkashi Iwama･Yoichiro Onishi･Toyohisa Shinmiya (JFE Steel)･Ayaka Honda･Yujiro Mitsui (SUBARU)

The application of bead-applied stiffening materials has been investigated to improve the panel stiffness of automotive outer panels. However, panel distortion caused by material shrinkage during the paint baking process is a critical issue. For vehicle implementation, it is necessary to determine appropriate bead dimensions (width and thickness) that do not induce distortion, but no reliable prediction method has been available. Through prototype testing of an actual vehicle door, it was found that incorporating material property changes during thermal curing significantly improves distortion prediction accuracy.

Quantitative Evaluation of the Effects of Single Blowhole Size and Through-Thickness Location on Stress State in Aluminum Alloy Welded Joints

Sogo Takuno･Eita Niisato･Kazumi Otake (Toyota Motor)

The application of aluminum alloys in automotive body structures has increased in recent years to achieve vehicle weight reduction. However, welded joints in aluminum alloys often exhibit lower strength than the base material, making the weld zone a potential structural weak point. As a result, manufacturing defects such as blowholes can significantly influence joint strength and remain a critical issue for quality assurance. Conventional evaluations have primarily focused on defect size and porosity. However, even defects of identical size can produce different stress states depending on their position within the cross section. This study aims to quantitatively clarify the combined effects of blowhole size and location on joint strength. Linear finite element analysis was conducted on aluminum alloy welded joints with varying blowhole diameters and positions to evaluate stress at crack initiation sites. In addition, machine learning was applied to efficiently analyze trends across multiple conditions. Experimental validation was performed through static and fatigue tests using specimens with artificial defects introduced by drilling. The results indicate that defect position has a greater influence on stress concentration than defect size. The combined evaluation of size and position enables a more systematic assessment of blowhole effects on joint strength.

Efforts to develop door deformation prediction technology in the paint drying process

Kazuki Shouyama (TOYOTA Auto Body)･Shinich Takezoe (TOYOTA AUTO BODY R&D)

In vehicle manufacturing, the fit of the body and doors is a crucial control item for ensuring exterior quality. Regarding the phenomenon of door shape change (hem misalignment) before and after the paint drying process, which is an influencing factor, we have conducted verification of the occurrence mechanism using component evaluation and developed a prediction technology using simulation, which we will now introduce.

Development of Gears with Low Heat Treatment Distortion

Yuudai Ookawa･Gou Katou･Makoto Maeda (JATCO)

Drivetrain gears acquire high strength and wear resistance through heat treatment, but the resulting thermal distortion necessitates a subsequent deformation correction step. Hollow-structured internal gears for planetary gear systems are particularly susceptible to severe deformation. To address this challenge, we have developed a novel combination of materials and processing methods that achieves both high strength and low distortion. This approach enables the production of high-precision gears while entirely eliminating the correction process.

Improving Catalytic Conversion Efficiency by Controlling Exhaust Pulsations

Takashi Esaki･Chie Honda･Shinya Sugihara (Sango)

When the engine operates under high load, the large exhaust flow causes high gas velocities within the catalyst, reducing its purification performance. In this study, the pulsation of the engine exhaust was investigated, and purification was improved by reducing fluctuations in flow velocity. Control of the velocity fluctuations within the catalyst was achieved by altering the internal structure of the muffler mounted downstream of the catalyst.

Modal Emission Modeling Using a Data-Driven Approach

Kohei Sakai･Takashi Araki･Takaaki Nagano･Michiharu Kawano (Mazda)

In automotive development, increasingly stringent emission (EM) regulations require effective allocation of functions at the vehicle level, driving the need for fast and accurate model-based emission prediction technologies. To address this challenge, this study proposes a data-driven model that combines steady-state performance maps with AI-based transient correction. Using this approach, a modal emission prediction method applicable to new vehicle configurations with specification changes is developed. The proposed method enables efficient and reliable emission prediction, supporting model-based development in early-stage vehicle design.

Numerical Computational Fluid Dynamics Analysis of Pd-based Three-way Catalysts Considering Detailed Surface Reactions
-Effects of Mass Transport in the Catalyst Layer-

Keita Inoue (Waseda University)･Soichiro Oda (Sapporo Breweries)･Sota Aoyama (Toyota Motor)

To advance exhaust purification efficiency, this study quantitatively evaluates mass transport phenomena within Pd three-way catalysts. CO-O₂ light-off tests were conducted using catalysts coated with an inert alumina top layer to isolate diffusion effects. A comprehensive 1+1D simulation model was developed, integrating physical parameters directly derived from mercury porosimetry and SEM observations. The proposed model successfully reproduced experimental light-off behaviors. Subsequent detailed internal analyses elucidated that under high-temperature conditions, catalytic reactions become strongly diffusion-limited, heavily concentrating near the washcoat surface.

Analysis of Molecular Diffusion in TWC Aggregated Particles with Interconnecting Pores and Evaluation of Reaction Rates in Their Layered Structures

Ryuta Chimoto･Mariko Watanabe (Sophia University)･Katsunori Hanamura (Japan Science and Technology Agency)

We calculated diffusion coefficients for porous ternary catalysts composed of nanoscale particle aggregates featuring submicron-scale interconnected pores using diffusion simulations. These coefficients were subsequently incorporated into a particle-layer model as a simplified representation of the porous structure. By conducting a comprehensive analysis integrating flow, diffusion, and reaction processes, we elucidated the combined effects of the interconnected pore network and particle stacking structure on the overall reaction rate.

Analysis of Cyclist Avoidance Behavior in Emergencies Using VR Simulation

Hiroya Sano･Yuqing Zhao (Nagoya University)

Half of fatal and serious injury accidents involving bicycles are crossing collisions with cars. This study developed a virtual reality bicycle simulator to conduct experiments simulating a car suddenly crossing. Cyclists' riding characteristics and emergency avoidance behaviors were measured to identify the behavioral factors determining collision avoidance success.

Modeling of Cyclist's Speed Decision Based on Acceleration and Deceleration Judgments at Unsignalized Intersection

Ryo Wakisaka･Takuma Yamaguchi･Kazunori Ban (Toyota Technical Development)･Hiroyuki Okuda･Tatsuya Suzuki (Nagoya University)

Bicycles exhibit diverse behavior due to ambiguous rule recognition, making them an important safety factor for automobiles. Therefore, modeling cyclist behavior is a critical issue for evaluating safety systems such as automated driving through simulations. This study develops a cyclist speed decision model for interaction scenes with left-turning vehicles at unsignalized intersections. The model is constructed using experimental data measured with a bicycle simulator and is evaluated through comparisons with the measured data.

Overtaking Decision Model for Cyclists Considering Interaction with Rear-Approaching Vehicles

Soya Oguri (Nagoya University)･Ryu Wakisaka (Toyota Technical Development)･Hiroyuki Okuda･Tatsuya Suzuki (Nagoya University)･Takuma Yamaguchi･Kazunori Ban (Toyota Technical Development)

This study proposes a hierarchical cyclist overtaking model focusing on psychological pressure from rear vehicles in mixed traffic. Using simulator data, we probabilistically model the decision process in two phases: intention estimation via an LSTM incorporating physical preparatory behaviors, and final execution decision. The model is verified against conventional methods.

Pedestrians Recognition of Vehicle Yielding Intent under Vehicle Deceleration Behavior and Its Modeling
-Analysis Based on Initial Speed, Deceleration Rate, and Deceleration Onset Position-

Kazusa Fukawa･Taiki Yoshikawa (Keio University)･Wataru Nakashima･Takeshi Waragaya (Stanley Electric)･Tatsuru Daimon (Keio University)

This study investigated pedestrians’ judgments of being yielded to and the cognitive process underlying the recognition of vehicle yielding intent under vehicle deceleration behavior using a VR experiment reproducing an unsignalized crosswalk environment. Vehicle initial speed, deceleration onset position, stopping position, and day/night conditions were controlled as experimental variables. The data were analyzed from the perspectives of judgment timing and psychological factors, and the effects of vehicle behavior on pedestrians’ cognitive and decision-making processes are reported.

The Effect of Pattern-Projection Headlamps on Reducing Nighttime Pedestrian Accidents

Tatsuya Iizuka･Yoko Kato･Yoshiro Aoki･Michiaki Sekine (NALTEC)･Kazuyuki Kawamura･Kei Oshida (Honda R&D)

To reduce nighttime pedestrian vehicle-to-accidents, the effect of a headlamp projecting a diamond-shaped pattern was evaluated through real-vehicle driving experiments. In experiments conducted from the driver’s perspective, pedestrian detection distance was measured, whereas in experiments conducted from the pedestrian’s perspective, vehicle detection distance was measured under distracted conditions caused by smartphone use. The proposed headlamp was compared with conventional driving-beam and passing-beam headlamps.

The Effects of Differences in Drivers' Brain Activity on Recognition of Left- and Right-Hand Curves and Driving Performance

Reon Ogawa･Kohjiro Hashimoto･Kikunori Shinohara (Suwa University of Science)･Masashi Makita (Teikyo University)･Hiroshi Kuniyuki (Suwa University of Science)

In this study, the relationship between drivers’ brain activity and driving performance on left- and right-hand curves was analyzed using a driving simulator. The results showed that activation in the right prefrontal cortex was associated with reduced deviation from the curve for both left- and right-hand curves. Furthermore, for right-hand curves, higher activity in the right frontal pole was associated with reduced deviation from the curve.

Analysis of Factors Leading to Disregarding Traffic Signal Accidents

Hiroshi Kuniyuki･Syunya Oshima･Ginpei Suzuki (Suwa University of Science)

In this study, high-accident locations in urban areas where accidents caused by drivers' disregarding traffic signals frequently were investigated and analyzed to clarify contributing factors. The results revealed that these locations are characterized by short intervals between traffic signals at intersections and the presence of a large intersection further ahead. It is considered that short intervals between traffic signals make drivers more likely to perceive these intersections as a single unit, while the presence of a major intersection ahead causes them to overlook the preceding intersection, which are the primary contributing factors to these accidents.

Development of Attribute-Based Driver Models Using a Driving Simulator
-(First Report): Development and application of driver models for cornering-

Shingo Sugiura (TOYOTA Systems)

This paper proposes a method to build attribute-specific driver models using a driving simulator. Using such models is expected to streamline fully virtual ECU evaluation when combined with various test scenarios. We collected simulator data from 41 drivers on a multi-curve course. From the data, we extracted driver features by attribute and built models for younger and older driver groups. We tuned a virtual ADAS using these models and evaluated driver acceptance for the target groups. The results support the effectiveness of the proposed attribute-based driver modeling method.

Evaluation of Stochastic Characteristics of Driver Pedal Operation for Interpreting Machine Learning-Based Pedal Operation Prediction Errors

Akihiro Matsumoto･Toshiya Hirose (Shibaura Institute of Technology)

Toward pedal misapplication detection, machine learning-based prediction of pedal operation has been investigated. However, drivers’ pedal operations are not fully deterministic and may vary even under the same driving conditions. Therefore, when evaluating a prediction model, it is necessary to consider not only the model’s predictive performance but also the stochastic variability inherent in human operation. This study quantitatively evaluates variations in pedal operation under identical conditions and examines basic indices for interpreting prediction errors in machine learning-based pedal operation prediction.

The Relationship Between Driver Home Range and Age, Travel Mode, and Residence
-Analysis Using Property Damage Only Crash Data as Samples of Driver Movement-

Kazunori Nishiki･Hanae Kosuge･Nobuaki Takubo (Institute for Traffic Accident Research and Data Analysis)

In this study, to analyze drivers' mobility behavior, we employed the distance between home and the accident location as a proxy measure for home range. Multiple regression analysis revealed three distinct patterns of age-related changes in home range, while also indicating significant variations based on transportation mode and residential area.

Analysis of Driver Behavior During Intersection Approach

Takuya Murakami (Mitsubishi Electric)･Yuji Matsuki (Fukuoka Institute of Technology)･Takara Myojin (Mitsubishi Electric Mobility)･Taichi Kojima･Asako Omote･Yudai Nakamura (Mitsubishi Electric)

This exploratory study aimed to examine everyday driving habits in a simple way. We used a driving simulator to compare experienced and novice drivers as they passed through intersections with varying visibility conditions. We found significant differences in stop-sign compliance and left-right safety checks. These results suggest that differences in the habituation of routine safety checks may explain the observed behavioral differences.

Effects of Video-Based Reflection and Positive Self-Evaluation on Anxiety in Novice Drivers

Hajime Yoshida･Rikuto Nakae･Yukiko Nishizaki (Kyoto Institute of Technology)

This study aimed to reduce novice drivers' anxiety in challenging driving scenarios by examining the effects of reflecting on their own driving by watching a video and positive self or other - evaluation after driving through a driving simulator experiment. Additionally, it investigated how traffic complexity influences the amount of anxiety reduction achieved through each reflecting method. In addition to evaluating anxiety reduction through subjective and physiological measures, changes in driving behavior were also assessed.

Evaluation of Driver Seating Fatigue during Long-Time Driving Using Motion and Static Driving Simulators

Kota Kurita･Yamato Masuda･Soichiro Hayakawa･Ryojun Ikeura (Mie University)･Tetsuya Kitagawa (Fortec)

This study aims to compare and examine the effects of seat motion on driver seating fatigue during long-time driving using both motion and static driving simulators. Fatigue evaluation was conducted using objective assessments based on various physical condition indicators, as well as subjective assessments through questionnaires. By comparing these indicators, differences in fatigue are clarified.

A Preliminary Proposal for a Method to Estimate Lumbar Load by Considering Seat and Backrest Reactions

Rintaro Manabe･Yoshio Tsuchiya (Kagawa University)

Sitting for long periods of time, such as while driving, is believed to be a cause of poor blood circulation and low back pain. To identify the causes of these issues, it is necessary to accurately assess the strain on the lower back. To this end, we measured the pressure exerted on the seat and backrest of a chair, developed a prototype model to estimate lower back strain based on these measurements, and conducted simulation evaluations.

Occupant Behavior Analysis in Seating Posture including Large Backrest Inclination
-Whole-Body Frequency Response Characteristics under Six-Axis Frequency Sweep Excitation-

Daichi Kato･Atsushi Kawaguchi (Toyota Central R&D Labs.)･Tetsuhiro Okuda (Toyota Boshoku)

Toward comfort evaluation in next-generation mobility, this study investigated occupant behavior in seating postures with large backrest inclination. Whole-body dynamic responses under six-axis frequency sweep excitations were measured using a motion capture system. The results of this preliminary study indicate that frequency response characteristics vary depending on backrest inclination and excitation direction.

Analysis of Pedal-Switching Characteristics During the Transition to Parking

Yudai Baba･Junya Inoue (Graduate School of Industrial Technology, Nihon University)･Keisuke Kazama･Yoshitaka Marumo (College of Industrial Technology, Nihon University)･Machiko Hiramatsu (Nissan Motor)･Hiroshi Mouri (Tokyo University of Agriculture and Technology)

This study aims to clarify the impact of the driving environment on pedal misapplication accidents. To achieve this, we measured and compared pedal operations during normal driving and parking. Pedal-switching behaviors were classified into "heel-pivot" and "foot-shifting" types. For the heel-pivot type, the heel position shifted toward the brake pedal during parking. We confirmed that this shift altered lower limb kinematics. These changes suggest a potential contribution to the occurrence of pedal misapplications.

Proposal of a Steering Assist System Considering Individual Driver Input Constraints
-Third Report: Actual Vehicle Evaluation with Drivers Simulating Physical Constraints-

Daisuke Nagasaka (J-QuAD Dynamics)･Akira Ito (Aichi Institute of Technology)･Hiroyuki Okuda･Hirofumi Aoki (Nagoya University)･Shigenori Ichinose (J-QuAD Dynamics)

The steering assist system proposed in previous reports, which considers individual driver input constraints, was evaluated in an actual vehicle with drivers simulating physical constraints. This report presents the evaluation results, including the effects on steering workload reduction and driving assistance.

Vehicle Attitude and Disturbance Suppression Control Based on Optimal Torque Allocation to Front and Rear Wheels

Ryo Watanabe･Nobutaka Wada (Hiroshima University)･Minoru Miyakoshi･Yasuhide Yano･Tomohiko Adachi･Seiji Fukui (Mazda)

This paper proposes a control method to stabilize vehicle attitude during acceleration and deceleration and minimize the impact of road irregularities on body motion by optimizing the distribution of braking and driving forces between the front and rear wheels. The proposed control law is derived based on model predictive control. The effectiveness of the proposed method is verified through numerical simulations.

Robust Performance Improvement of Automotive Powertrain Control Systems Using Deep Reinforcement Learning Considering Parameter Variations

Hiroki Shibata･Heisei Yonezawa (Hokkaido University)･Shota Sato･Hiroya Kikuchi･Takashi Hatano･Shuichi Kondo･Shigeki Hiramatsu (Mazda)･Itsuro Kajiwara (Hokkaido University)

In automotive powertrain systems, reducing low-frequency vibration during acceleration remains a challenging issue. Since model-based control systems depend on system models, their control performance may degrade due to parameter variations in actual plants. This study obtains a control policy using deep reinforcement learning that accounts for parameter variations, thereby improving vibration suppression and robust performance under varying conditions.

Development of Method for Deriving Comprehensive Use Cases on Public Roads for Functional Safety Analysis

Yoshihiro Miyata･Shuhei Kashihara･Takayuki Nakano (Nissan Motor)

In hazard analysis for systems operating on public roads, countless use cases must be considered, and defining them requires a tremendous amount of time. Demonstrating coverage is also difficult. This issue is especially relevant for autonomous driving systems that perform diverse vehicle control functions. We have developed a method for deriving use cases that addresses these issues. In this presentation, we report the developed method and its application examples.

Wireless Channel Measurement and Network Bonding Emulation for Mobility Systems

Saya Yamamoto･Ryu Atsuta (1FINITY Mobile Techno)

This study investigates a network bonding technique using multiple wireless interfaces to provide a stable communication environment for mobility systems. We measured wireless characteristics using a cellular measurement system based on smart devices and emulated the effectiveness of network bonding. We report the results of these evaluations.

Network Bonding Field Testing for Mobility Systems

Ryu Atsuta･Saya Yamamoto (1Finity Mobile Techno)

In this study, we investigated network bonding technology using multiple wireless interfaces to provide a stable communication environment for mobility systems. We developed a network bonding testbed using smart devices and conducted tests. This presentation will report on the results.

Simulation-Based Evaluation of One-to-Many Remote Support for Automated Driving Services

Yanbin Wu･Toshihisa Sato･Naohisa Hashimoto (AIST)

In the implementation of Level 4 automated mobility services, operations in which a remote supervisor monitors multiple vehicles must achieve both safety and efficiency. This study developed a remote supervision simulator and conducted experimental evaluations of remote supervision tasks and operational simulations to examine how the number of monitored vehicles affects safety and efficiency, as well as the operational constraints of one-to-many supervision.

Effect of Steering Torque Feedback Timing on Driver Control in Teleoperation Driving

Ryotaro Hosoi･Keiji Jimi (Gunma University)･Toshiki Kanbayashi (SUBARU/Gunma University)･Ren Okuma･Hisato Fukuda (Gunma University)･Toshihiko Kozai･Tsutomu Iwase (Gunma University/SUBARU)

In teleoperated driving, steering resistance and reaction forces from the road surface are not transmitted to the driver, making stable steering difficult. In this study, we generate steering torque feedback using a non-linear tire model on a driving simulator. We evaluate its effectiveness for vehicle control assistance and report the results on how the presentation timing of steering torque feedback affects driver operations.

A Simulator Study on the Effects of Teleoperation Video Quality and Driving Support by White Line Enhancement

Ren Okuma･Keiji Jimi (Gunma University)･Toshiki Kanbayashi (SUBARU/Gunma University)･Ryotaro Hosoi･Hisato Fukuda (Gunma University)･Toshihiko Kozai･Tsutomu Iwase (Gunma University/SUBARU)

In teleoperation, the communication environment fluctuates significantly; however, stabilizing the connection can be expected by reducing video quality. Conversely, a decline in video quality degrades the perception of the surrounding environment, making stable maneuvering difficult. This study compares the effects of a low-resolution state with those of lane-marker enhancement, and reports the effects of lane-marker enhancement under low-resolution conditions on driving behavior.

Evaluation of Vehicle Dynamic Performance on Snowy Roads Using a Driving Simulator and Reforming the Development Process

Tatsuhiko Nakajima (Toyota Motor)

Evaluation of vehicle dynamic performance on snowy roads is essential but time-consuming. This study integrates a driving simulator with vehicle and control models to build an MBD (model-based development) evaluation environment. By coupling and visualizing physical quantities in real time, it enables the identification of issues and consideration of countermeasures before conducting full vehicle tests. As a result, we confirmed a reduction in evaluation time and improved efficiency, offering guidance for transforming the development process.

Proposal of an Integrated Vehicle Development and Production Architecture Based on Manufacturing-Induced Physical State Variables

Ichiro Tanaka･Hiroyoshi Horibe･Takayuki Fujii･Eisei Higuchi (Honda R&D)･Mitsuhiro Takayama (Former Honda R&D)

This paper proposes a vehicle development and production integrated architecture in which a CAE predicting manufacturing-induced physical state quantities accumulated across multiple body production processes serves as a core hub, enabling physically consistent coupling of body four-major-performance CAE, manufacturing robot simulations, and prediction models of CO₂ emissions during production based on common physical state variables.

Digital Twin Construction Technology through Information Circulation between CAE and Manufacturing Robots

Takayuki Fujii (Honda R&D)･Takahiro Jinnai (Honda Motor)･Kazuto Ito (Digital Process)･Seiji Tsukada (Progress Technologies)･Ichiro Tanaka (Honda R&D)

This study proposes a digital twin construction technology aimed at eliminating discrepancies between design and manufacturing through information circulation between CAE and manufacturing robots. By reflecting robot operation conditions in CAE and feeding back on-site adjustment data, prediction accuracy is improved, and its effectiveness is validated through application to actual production.

Numerical Simulation of Airbag Inflation Using a Discrete Membrane Model Toward Prediction of In-Vehicle Pressure Changes

Satoshi Nohara (Kobe University)･Shinsuke Shibata･Kazuki Hikida･Hisaki Sugaya･Atsushi Hasegawa (Honda R&D)･Makoto Tsubokura (Kobe University)

Barotrauma cases potentially associated with transient in-vehicle pressure changes have been reported in the context of airbag performance enhancements, including increased inflation speed and deployment in new locations. In this paper, we present numerical simulations of airbag inflation under specified internal pressure using a newly developed discrete membrane model, and explore the potential applicability of the proposed method to fluid–structure interaction simulations aimed at developing methods for predicting in-vehicle pressure changes.

Study on Optimization Design Methodology for Heat components of electric vehicles using an FMI-Based Integrated Vehicle Model

Ryusaku Sawada (Sawada R&D)･Makoto Koekiba (Chuozuken)

To optimize EV thermal components early in development, this study proposes a system simulation approach. Lightweight 1D thermal-fluid models based on empirical data are integrated via FMI into a Simulink environment covering the vehicle, drivetrain, and HVAC. Parametric analysis of thermal resistance and capacity demonstrated that this method rapidly identifies robust, optimal component specifications affecting energy consumption and temperature behavior under various driving conditions, without relying on high-overhead 3D CFD.

Effects of Partial Forging on the Fatigue Strength of Cast Aluminum Alloys

Kento Shimizu･Mikiya Nozaki･Soichiro Ishida･Yoshihiro Maekawa･Masaaki Hirakawa･Kensuke Yoshizue (Toyota Motor)･Tomohiro Suzuki (Toyota Industries)･Takushi Isono (Toyota Motor)

Fatigue cracks in cast aluminum alloys are known to initiate from casting porosity defects. In this study, partial forging was applied to artificial defects simulating casting porosity, and the effects of defect size and defect crushing on fatigue strength were investigated. The experimental results showed that applying forging perpendicular to the principal stress direction affected the fatigue strength characteristics and crack propagation behavior.

Weight Reduction of Automotive Suspension Parts using 980MPa Class Steel

Takahiro Otani･Masaaki Tanaka･Hiroki Kimura (Mazda)

Vehicle dynamics performance and environmental performance are necessary for realization of " joy of driving " and "the superior environmental performance" that Mazda aims at. It is effective to reduce the thickness of stamping parts to send this thought to more customers. However, the coexistence at the high level of rigidity, strength, the anti-corrosion performance is demanded. I report the result that solved these problems by evolution of the elemental technology.

Investigation of Fatigue Characteristics of Adhesive–Rivet Hybrid Joints under Peel Loading

Chihiro Wada･Hiroaki Kawamura･Eita Niisato･Sohgo Takuno (Toyota Motor)

This study investigates the fatigue characteristics of adhesive–rivet hybrid joints for lightweight and multi-material automotive body applications. While previous studies have mainly focused on shear and tensile loading, the static and fatigue characteristics under peel loading were evaluated using specimens representing flange regions in vehicle bodies. The results show that fatigue behavior is governed by the rivet in the high-load region, whereas in the low-load region, load sharing by the adhesive improves fatigue strength.

Relationship between Void Distribution Function of Soft Polyurethane Foam and Mechanical Property (Compression Force - Displacement Characteristic)
-(Third Report) Compression Force - Displacement Characteristics Studies By Means of Void Distribution Function-

Minoru Inoue (Mazda/Kagawa University/Hirosima University)･Keisuke Suzuki (Kagawa University)･Hiroyuki Ito (Toyo Seat)･Toshihiro Yoshida (Mazda)

By means of CAE methodology to evaluate mechanical properties (compression force - displacement characteristics, hereafter F-S characteristics) of the soft urethane foams using void distribution function, which was verified and improved by the preceding papers, F-S characteristics studies by changing void distribution function curves were performed and executed. Then properties and parameters of void distribution functions which affect compression F-S characteristics are clarified and possibilities to control F-S characteristics of soft urethane foams are presented.

A Study on an Efficient Duct Component Evaluation Method Using Fluid Topology Optimization

Yoshio Itoh･Satoshi Ito (Toyota Motor)･Fumiya Shiratsu･Masahiko Kono･Toshiki Watanabe (Toyota Systems)

This study proposes an efficient HVAC duct design method based on fluid topology optimization. Conventional design relies on iterative CFD analysis and CAD modifications, resulting in high development effort. The proposed workflow enables automatic generation of optimized duct geometries while incorporating outlet boundary conditions, including downstream register effects. The results were validated through experiments using 3D-printed prototypes and a component test bench. It was demonstrated that outlet boundary conditions have a significant impact on pressure loss and optimized shapes. The proposed method improves performance under realistic operating conditions and reduces development effort by approximately 24 hours per phase.

Prediction of In-Cylinder States under Multiple Injection Conditions Using a Reduced-Order Model Derived from 3D CFD

Hiroki Nagashima･Ryo Adachi･Yousuke Eguro･Kouyou Nakagawa･Takuma Katsuragawa (SUBARU)･Natsuki Ishizawa (IDAJ)

Improving development efficiency is essential to achieve high performance, fuel economy, and emission reduction. Multiple injection strongly influences emissions, while 3D CFD analyses over a wide range of operating conditions require high computational cost. This study proposes a method to estimate in-cylinder states under various injection timings using a Reduced-Order Model (ROM) derived from CFD result.

Combustion and Exhaust Gas Characteristics of a Spark-Ignition Engine using Carbon Neutral Fuels (MtG: Methanol to Gasoline, EtG: Ethanol to Gasoline)

Chihiro Kishimoto･Haruto Morimoto･Ratnak Sok (Waseda University)･Kou Osada･Ryota Yamada (Toyota Motor)･Jin Kusaka (Waseda University)

This research experimentally investigates the effects of MtG and EtG on combustion and exhaust characteristics in spark-ignition engines from low to high load ranges. No differences were observed in brake thermal efficiency between fuel types. However, differences were confirmed in exhaust gas composition. This suggests that the influence of each fuel's evaporation characteristics on the mixture formation process is a contributing factor.

Combustion and Exhaust Gas Characteristics of a Spark-Ignition Engine using Ethanol-Blended Carbon Neutral Fuel (MtG: Methanol to Gasoline)

Haruto Morimoto･Chihiro Kishimoto･Ratnak Sok (Waseda University)･Kou Osada･Ryota Yamada (Toyota Motor)･Jin Kusaka (Waseda University)

This research investigates the effects of adding ethanol to gasoline and MtG on engine performance by engine dynamometer testing. Ethanol addition enabled ignition timing advance, resulting in improved brake thermal efficiency. Furthermore, CO, NO, and THC emissions were reduced. No significant difference in ethanol addition sensitivity was observed between gasoline and MtG.

Construction of a Chemical Kinetic Mechanisms for Carbon Neutral Fuels (MtG: Methanol to Gasoline, EtG: Ethanol to Gasoline) in Spark-Ignition Engines

Chihiro Kishimoto･Haruto Morimoto･Ratnak Sok (Waseda University)･Kou Osada (Toyota Motor)･Jin Kusaka (Waseda University)

This research investigates the combustion characteristics of gasoline, MtG, and EtG by experiments using constant-volume combustion chamber and detailed chemical reaction analysis. It was confirmed that MtG and EtG tend to exhibit lower laminar flame velocities and lower adiabatic flame temperatures compared to gasoline. Sensitivity analysis showed that heavy aromatic components in the fuels were the cause of the decrease in laminar flame speed.

Synthetic Gasoline Production by MTG (Methanol to Gasoline) Process and Quality Adaptation
-Consideration of Gasoline Production through Comparison with FT Synthesis-

Kenichi Okamoto･Naoki Amitani･Noriyuki Aratani･Nobuo Oyama･Akio Imai･Seiya Suzuki･Noriaki Ohmori･Hiroshi Kisai (Japan Petroleum and Carbon Neutral Fuels Energy Center)

To address global warming and reduce greenhouse gas emissions, early introduction of bioethanol and synthetic gasoline for transportation fuels is strongly required. In this study, MTG (Methanol to Gasoline) synthesis was experimentally conducted, and the quality characteristics of the obtained MTG crude oil were analyzed to investigate approaches for complying with gasoline specifications through fuel property adaptation. In addition, production efficiency was compared with FT synthesis gasoline, and future directions for synthetic gasoline production and utilization were discussed from the viewpoints of fuel quality and manufacturing efficiency.

Comparison of Laminar Burning Velocities Between e-Fuels and Conventional Fuels

Dai Matsuda･Kei Kikuchi (Kyushu University)･Kenichi Okamoto･Nobuo Oyama (Japan Petroleum and Carbon Neutral Fuels Energy Center)･Ekenechukwu CHIJIOKE Okafor (Kyushu University)

To clarify the fundamental combustion characteristics of carbon-neutral fuels for application to spark-ignition engines, laminar burning velocities were measured using a constant-volume combustion vessel for commercial gasoline, MTG fuel, and a prototype FT synthetic fuel using synthetic gasoline obtained by JPEC through a NEDO-commissioned project. The equivalence ratio dependence was evaluated, and the effects of fuel composition and carbon structure on laminar burning velocity are discussed.

Engine Combustion Characteristics of Olefin-Rich Gasoline Derived from Fischer–Tropsch Synthesis

Kohei Kuzuoka･Mitsuharu Oguma (AIST)･Kenichi Okamoto (Japan Petroleum and Carbon Neutral Fuels Energy Center)

Fischer–Tropsch (FT) -derived fuels inherently face challenges in achieving sufficient anti-knock performance in gasoline engines. In this study, a surrogate fuel representing olefin-rich FT-derived fuel compositions was employed based on the assumption of an FT catalyst capable of directly producing olefin-rich fuels. Engine experiments clarified the influence of fuel composition on knock characteristics under various operating conditions. The findings provide insight into the relationship between olefin-rich fuel compositions and knock resistance behavior in gasoline engine operation.

Effects of azeotropic phenomena in ethanol-blended gasoline on liquid film evaporation characteristics during cold start

Siryu Sato･Kenji Tamura･Tomoki Nagata (Waseda University)･Kenji Uchida･Junki Hori･Shinya Iida (Mazda)･Jin Kusaka (Waseda University)

Liquid film evaporation characteristics of ethanol-blended fuels were investigated using a constant-volume chamber and 3D-CFD. Ethanol was found to promote the evaporation of high-boiling-point components through azeotropy, a phenomenon further confirmed in simulations incorporating an azeotropic correction model. The numerical results led to the conclusion that evaporation characteristics are governed by two competing factors related to temperature drop: the enhancement of evaporation rates due to azeotropy and the increase in latent heat of vaporization.

A Fundamental Study on the Impact of Light (Ethanol) and Heavy Components on Gasoline Deposits under Heating–Cooling Cycles

Tomoharu Kataoka (Toyota Motor)･Yoshinori Nakayama (SOKEN)

In recent years, the implementation of ethanol and synthetic gasoline has been accelerated as part of global efforts to reduce CO₂ emissions. Furthermore, previous studies have reported that cyclic heating–cooling treatments accelerate the hardening of gasoline deposits. In this study, the effects of light components, such as ethanol, and heavy components associated with synthetic fuels on deposit formation under heating–cooling cycles are investigated.

Study on Modeling of Combustion Chamber Deposits in High-Efficiency Gasoline Spark-Ignition Engines (Third report)
-Sensitivity Evaluation of Carbon-Neutral Fuel Components on Deposit Formation Using a Visualized Constant-Volume Vessel-

Kazuma Motohashi･Kotaro Tanaka･Satoshi Sakaida (Ibaraki University)･Koichi Kinoshita･Yohko Abe (AIST)･Shinsuke Mori･Satoshi Kodama (Institute of Science Tokyo)

To reduce carbon dioxide emissions, the use of carbon-neutral (CN) fuels has been extensively considered; however, deposit formation remains a significant concern. This study aims to develop a predictive model for combustion chamber deposit formation. In this report, a visualization constant-volume vessel simulating a combustion chamber was employed to clarify the effects of CN fuel components on deposit formation.

Study on Modeling of Combustion Chamber Deposits in High-efficiency Gasoline Spark-Ignition Engines (Fourth Report)
-Evaluation of Deposit Formation under Carbon-Neutral Fuel Conditions Using an Autoclave-

Koichi Kinoshita･Yohko Abe (AIST)･Kotaro Tanaka･Satoshi Sakaida (Ibaraki University)･Shinsuke Mori･Satoshi Kodama (Institute of Science Tokyo)

In recent years, carbon-neutral fuels, such as synthetic fuels, have been considered as alternatives to fossil fuels; however, deposit formation associated with their use remains a concern. This study aims to clarify the formation mechanisms of combustion chamber deposits, establish suppression methods, and develop predictive models. In this report, deposit formation experiments were conducted using an autoclave under conditions simulating carbon-neutral fuels, and the formation behavior and characteristics of the resulting deposits were evaluated.

Study on Modeling of Combustion Chamber Deposits in High-efficiency Gasoline Spark-Ignition Engines (Fifth Report)
-Development of a Predictive Model for Deposit Growth Rates in Carbon-Neutral Fuels Integrating Engine Data and Laboratory Simulations-

Shinsuke Mori･Satoshi Kodama (Institute of Science Tokyo)･Koichi Kinoshita･Yohko Abe (AIST)･Kotaro Tanaka･Satoshi Sakaida (Ibaraki University)

In recent years, improving the efficiency of internal combustion engines and utilizing carbon-neutral fuels have become increasingly important. Meanwhile, deposits formed and accumulated in combustion chambers are a concern because they can induce abnormal combustion phenomena. Therefore, this study aimed to develop a predictive model for combustion chamber deposit growth rates in carbon-neutral fuels. In this report, simulated deposit formation experiments were utilized to investigate the effects of fuel composition on deposit growth characteristics. Furthermore, model development incorporating data obtained from actual engine tests was also examined.

Development of ammonia/hydrogen SI engine
-Initial Performance and Effects of Ignition Energy in Ammonia/Hydrogen PFI Engine-

Ryo Murakami (Daihatsu Motor)

This presentation is a follow-up report to the 2026 JSAE Annual Congress Spring. A co-firing engine supplying ammonia and hydrogen with PFI was developed, and the engine performance and the hydrogen addition ratio required for stable combustion were verified using the actual engine. In addition, the effects of the spark plug gap and ignition energy on combustion at the starting operating point were evaluated, and the results are reported in this presentation.

Research on the Effect of Hydrogen Mixing on Knocking in Spark-Ignition Natural Gas Engines

Wataru Nishio･Taketoshi Shimizu (Waseda University)･Kei Yoshimura･Satoshi Tokuhara (Suzuki Motor)･Jin Kusaka (Waseda University)

The effects of hydrogen addition on knocking characteristics in a spark-ignition engine fueled with HCNG were investigated through experiments and numerical analysis. The results showed that hydrogen enrichment increases knocking intensity, while its effect on knock onset timing is limited. To investigate the underlying mechanism, reaction pathway analysis was conducted. The analysis indicates that enhanced oxidation reactions during autoignition via the HO₂/H₂O₂ reaction system are primarily responsible for the increased knocking intensity.

A Study on Communication of Yielding Intention through Automated Vehicle Deceleration Behavior at Unsignalized Crosswalks

Taiki Yoshikawa･Kazusa Fukawa (Keio University)･Wataru Nakashima･Takeshi Waragaya (Stanley Electric)･Tatsuru Daimon (Keio University)

This study investigates how pedestrians recognize a vehicle’s yielding intention from its deceleration behavior at unsignalized crosswalks. Focusing on behavioral conditions such as the vehicle’s initial speed and deceleration start position, the effects of these differences on pedestrian perception are analyzed through real-vehicle experiments. The objective of this study is to clarify the characteristics of deceleration behavior that make a vehicle’s yielding intention difficult for pedestrians to recognize.

Effects of Dark Conditions on Pedestrian Crossing Decisions

Wataru Nakashima (Stanley Electric)･Taiki Yoshikawa･Kazusa Fukawa (Keio University)･Takeshi Waragaya (Stanley Electric)･Tatsuru Daimon (Keio University)

This study analyzed the effects of dark conditions on pedestrian crossing decisions under a scenario in which an automated vehicle yields to a pedestrian at an unsignalized crosswalk. Based on real-world vehicle experiments, whether participants recognized that the vehicle yielded was recorded as a binary outcome, and statistical analyses including interaction effects were conducted using vehicle behavior as explanatory variables.

Emotional Evaluation of a Cross-Modally Aware Forward-View Video Driving Support System

Tori Nakano･Shoichiro Takehara (Sophia University)･Hideki Sakamoto (ALPS ALPINE CO., LTD.)

This study investigated cross-modal effects produced by a combination of auditory and vibrotactile cues to achieve intuitive and comfortable left-turn guidance. An SD (Semantic Differential) method experiment was conducted using left-turn guidance scenarios, and the effects of different stimulus conditions on emotional evaluations were organized to derive design guidelines.

Consideration of an Alert Method Using Positional Correspondence Between Seat Vibration and Attention Targets
-(Third Report)-

Yosuke Uemura (Kyoto Institute of Technology)･Tetsuya Kitagawa･Ryuji Furumai (Fortech)･Yukiko Nishizaki (Kyoto Institute of Technology)

We reinvestigated the facilitative effect of seat vibration–induced spatial attentional orienting, previously examined using simple visual stimuli, on target detection in a dynamic visual environment with real-world driving footage. Consistent with previous findings, presenting seat vibrations congruent with the appearing location of the attention target significantly reduced reaction times for both younger and older groups. Furthermore, subgroup analyses of younger-old and older-old adults suggested that the characteristics of attentional orienting induced by seat vibration may vary across stages of aging.

Right-Turn Decision Support Based on Dynamic Gap Distribution Prediction at Multi-Lane Intersections

Haru Ishizuki･Hiroyuki Okuda (Nagoya University)･Takuma Yamaguchi･Kazunori Ban (Toyota Technical Development)･Heishiro Toyoda (Toyota Motor)･Tatsuya Suzuki (Nagoya University)

This study proposes a right-turn decision support system for multi-lane intersections that utilizes wide-area infrastructure sensor data to account for the lane-changing behavior of oncoming vehicles. The system dynamically and probabilistically predicts the gap distribution caused by lane changes, and supports optimal decision-making to maximize the driver's expected utility by balancing the trade-off between safety margins and waiting time.

Brake Operation Characteristic Design Considering Ankle Joint Passive Resistance for Full Brake by Wire Systems

Tomohiro Yokoyama･Kengo Ito･Shotaro Kaga (Toyota Motor)･Hiroshi Yoshitake･Motoki Shino (Institute of Science Tokyo)

In conventional hydraulic brake systems, pedal stroke is structurally constrained because the system is designed based on the fluid volume and master cylinder stroke required to reliably generate braking force. As a result, brake pedal characteristics have traditionally been optimized with priority given to hydraulic feasibility, making it difficult to freely design the pedal operation system based on human operation characteristics. In contrast, the application of brake-by-wire (BbW) technology mechanically decouples pedal operation from brake force generation, allowing system design to be freed from fluid-volume and mechanical constraints. This enables new possibilities for designing brake operation systems based on human characteristics. With BbW technology, the relationship between pedal force (Force), pedal stroke (Stroke), and vehicle deceleration (G), namely the F-S-G characteristics, is no longer restricted by mechanical constraints, resulting in a significant increase in design freedom. This has made it possible to design a wide range of brake operation characteristics with an emphasis on pedal feel and reduction of driver workload. For example, not only pedal reaction force but also pedal stroke itself can now be treated as a design variable, enabling the reconstruction of operation styles that were difficult to realize under conventional hydraulic constraints. Consequently, brake operation systems that better match human movement characteristics—such as operation based on heel support utilizing the natural rotational motion of the ankle joint—can be considered feasible. On the other hand, the design of F-S-G characteristics still relies heavily on subjective driving evaluations and empirical tuning, and systematic design guidelines grounded in human characteristics have not yet been sufficiently established. Previous studies have focused on ankle-dominant braking behavior and have shown that, in muscle-driven control regions where the soleus muscle acts as the primary contributor, the relationship between operation input and perceived deceleration can be approximated by the Weber–Fechner law. However, vehicle evaluations and subjective assessments have also confirmed that pedal force is generated even under relaxed conditions and that this force significantly influences the initial brake pedal feel. Such initial operation characteristics have not been clearly theorized under conventional design concepts based on fluid volume and stroke constraints. In this study, the origin of the pedal force generated under relaxed conditions is redefined as joint passive resistance at the ankle joint, and a brake operation characteristic design method that explicitly incorporates this effect into the F-S-G characteristics is proposed.

A Study on Enhancing Driver Situational Awareness Using Seat Haptic Stimuli via Multi-Vibrator Configurations

Yukiyo Kuriyagawa (Nihon University)･Hidefumi Koizumi･Shinichi Sagawai･Hirosh Wakuda･Toshiki Nakamura･Keigo Abe･Kunio Sato (Alps Alpine)

運転者⽤シート振動による触覚刺激を視聴覚刺激の代替やこれらと組み合わせて⽤いることで, 快適で直感的な運転⽀援効果を得ることを⽬指している．本研究では, シート内の複数振動子を組み合わせることで, ドライバの車両周辺等への状況認識向上効果を図った検討結果を述べる．

Theory of Personalized HMI Design for Promoting Safe Driving Using Structural Equation Modeling

Kaito Murotani･Keisuke Suzuki (Kagawa University)･Emiko Yoshida (Aioi Nissay Dowa Insurance)

Based on one-week real-world driving data and surveys of individual characteristics, this study proposes an information-presentation HMI design methodology that integrates latent psychological factors (personality) with manifest factors (driving behavior). We enhanced the reliability of the presented information by visualizing causal structures via Structural Equation Modeling (SEM), thereby employing a transparent logic distinct from black-box AI. By delivering warnings optimally tailored to individual drivers, this novel design paradigm effectively achieves both user trust-building and safe driving, establishing a vital framework for the approaching Software-Defined Vehicle (SDV) era.

Structure of Model to Quantify Psychological Aspects of Tactile Feedback to Switches

Hideki Sakamoto (Alps Alpine)･Hyoungsun Kim (Tohoku University)･Syota Takeuchi (Alps Alpine)･Wenyu Zhang･Chunlin Liu･Yi Ding (Tohoku University)･Hisato Shimomura･Kunio Sato (Alps Alpine)･Motoaki Sugiura (Tohoku University)

Switches installed in automotive cockpits are required to provide various operational tactile sensations depending on their intended functions. Although subjective evaluation has been used to assess these tactile sensations, it is well known that the evaluation items representing psychological quantities exhibit large inter-subject variability, making objective assessment difficult. This study aimed to clarify the sensory dimensions of tactile experiences by identifying their neural representations in the brain using fMRI, and to establish an objective evaluation method based on neural indices.

Structure of Model to Quantify Psychological Aspects of Tactile Feedback of Switches (Third Report)

Yuya Nanaeda･Hideki Sakamoto (Alps Alpine)･Shoichiro Takehara (Sophia University)

Switches equipped in the cabin of automobiles require various tactile feedbacks depending on their purposes for each user. In this study, we identified the factors that classify individual preferences by analysis based on subjective evaluation results of tactile feedbacks when pressing a switch. In addition, we constructed models which showed correlation between psychological quantity and mechanical properties for each evaluator group categorized by attributes.

A Study on a Quantitative Evaluation Method for Daytime Visibility of Automotive Interior Illumination Using CIELAB

Seong Uk Kim (Hyundai Motor)

Daytime visibility assessment of automotive interior illumination has traditionally relied on subjective evaluation, leading to inconsistent pass or fail criteria. This study proposes a quantitative method based on LMK imaging photometer measurements in CIELAB color space. Although dE00, a conventional color difference metric, did not correlate well with visual perception, dLstar and LCR were found to be more effective indicators of daytime visibility. Empirical analysis showed that daytime visibility was insufficient when dLstar was below 4.5 or LCR was below 0.06. This luminance based criterion enables objective and reproducible evaluation for automotive interior illumination design.

Cooling Loss Reduction in a High-Compression-Ratio HD Diesel Engine with an Optimized Combustion Chamber and a High Flow Rate Nozzle

Tomoyuki Mukayama･Noboru Uchida (New A.C.E. Institute)

To achieve even higher thermal efficiency in heavy-duty commercial diesel engines, achieving a higher compression ratio and developing novel designs and technologies, which can drastically reduce escalating cooling loss with increased compression ratio, are essential. In this study, following numerical investigation of an optimized combustion chamber geometry at a compression ratio of 23.5, the achieved design guideline was applied to a compression ratio of 26. As a result, significant cooling loss reduction effect was also experimentally confirmed with the prototype high-compression-ratio piston combined with a high flow rate nozzle with larger orifice diameter by utilizing a single-cylinder heavy-duty diesel engine.

CNN-Based Virtual Sensing of Rate of Heat Release for Fuel-Robust Diesel Engine Control (First Report)
-Rate of Heat Release Estimation and Improvement in Estimation Accuracy-

Ryo Sekiguchi･Takeshi Okamoto･Hisashi Ozawa (Isuzu Advanced Engineering Center)･Akihiro Yanai･Ratnak Sok･Jin Kusaka (Waseda University)

To enable the future use of diverse carbon-neutral fuels, robust combustion control is required to achieve target engine performance regardless of fuel properties, without fuel-specific engine calibration. In this study, RHR-based combustion control logic for feedback correction of engine control variables was developed using a convolutional neural network (CNN) -based rate of heat release (RHR) estimation method. The accuracy of RHR estimation was evaluated for diesel fuels with different cetane numbers using in-cylinder pressure and rotary-encoder-derived crank-angle acceleration. The results clarify the influence of training conditions and image resolution on estimation accuracy and demonstrate the feasibility of fuel-robust combustion control.

Effects of Fuel Physical Properties on Spray and Combustion Characteristics in a Diesel Engine
-Part1: Effects of Fuel Properties on Air Entrainment Near the Nozzle in Diesel Sprays-

Ryota Kobayashi･Gakuto Aizawa･Yoshio Zama (Gunma University)･Takeshi Hashizume (Toyota Motor)

The application of carbon-neutral (CN) fuels to compression-ignition engines has been expected to further reduce environmental impact. There is possibility that physical properties of CN fuels such as surface tension are different from those of conventional diesel fuel, and it is expected that characteristics of air entrainment induced by a spray are changed due to differences in the physical properties. Therefore, the surroundings gas flow of the spray near the nozzle exit was evaluated using a fluorescent PIV technique, and the effect of fuel physical properties on the air entrainment in a spray was investigated.

Effects of Fuel Physical Properties on Spray and Combustion Characteristics in a Diesel Engine
-(Part 2) Effects of Fuel Physical Properties on Combustion and Exhaust Gas Emission Characteristics-

Yuma Endo･Mitsuki Shida (Waseda University)･Takeshi Hashizume (Toyota Motor)･Jin Kusaka (Waseda University)

In this study, experiments were conducted using five fuels with different physical properties in order to clarify the effects of fuel physical properties on diesel combustion. A single-cylinder diesel engine was used as the test engine, and the air entrainment rate was estimated using a two-zone model. The results showed that earlier air entrainment enabled particulate matter reduction even at lower injection pressures than those used conventionally.

A study on Optimization of Combustion Chamber Geometry in Large Diesel Engines Using CFD and Machine Learning

Ryo Matsumae･Tomohiro Matsuda･Jin Kusaka (Waseda University)

Optimization of diesel engine combustion chamber geometry, including lip diameter, lip depth, and re-entrant angle, was conducted using thermal efficiency, soot, and NOx emissions as objective indices. An ANN-based surrogate model was developed to estimate the relationship between combustion chamber geometry and performance metrics, and PSO was applied for optimization. Sensitivity analysis clarified the influence of each geometric parameter, and chamber geometries achieving both improved thermal efficiency and reduced emissions were explored.

A study on Optimization of Combustion Chamber Geometry in Large Diesel Engines Using CFD and Machine Learning
-Analysis of the optimal shape that reflects the design intent-

Ryo Matsumae･Tomohiro Matsuda･Jin Kusaka (Waseda University)

This study evaluates the in-cylinder phenomena of two combustion chamber shapes optimized using Particle Swarm Optimization (PSO). For the balanced shape, suppressing excessive flow velocity reduced wall heat loss, achieving both low emissions and high thermal efficiency. In contrast, the efficiency-priority shape enhanced initial combustion and late-stage oxidation through increased turbulence and fuel spray collision with the lip edge. These results provide a physical basis for PSO-optimized designs and demonstrate that specific combustion strategies can be realized by adjusting the weighting factors of the objective functions in the PSO evaluation.

Effect of PM Reduction due to Hydrogen Oxygen Gas addition to intake air in Diesel Engines

Kanta Kasugai･Takafumi Kato･Ryosei Takeda･Ryoma Ohnishi･Kensei Kurita･Yoshiaki Nishijima (Aichi Institute of Technology)

It is expected to improve fuel efficiency by using of addition of the generated Hydrogen Oxygen GAS in the intake air of an engine. We use the hydrogen oxygen gas produced by electrolysis of water. As a result, we measure a reduction in the mass of particulate matter ad PM in the exhaust gas.

Visualization and Analysis of Formaldehyde Formation and Consumption in Diesel Spray Combustion

Toshiaki Hijima･Tomohiro Hayashi (SOKEN)･Sho Fukuda･Takashi Kawachi･Yuto Tsutsui (Toyota Industries)

With the advancement of fuel diversification driven by carbon neutrality, variations in fuel properties significantly affect combustion and emission characteristics in diesel auto-ignition combustion. In this study, focusing on in-cylinder formaldehyde distribution as an effective indicator of combustion state, a visualization and analysis technique based on chemiluminescence and laser-induced fluorescence (LIF) using a rapid compression expansion machine (RCEM) was developed.

Effects of Intake Gas Conditions on the Carbon Crystallite Size of Soot Particles from a Diesel Engine

Mao Takeuchi･Miyu Yamamoto･Yu Kuroshima･Kazuki Inaba･Kazuhiro Hayashida (Kitami Institute of Technology)

In this study, the effects of intake gas conditions (pressure, temperature, and oxygen concentration) on the carbon crystallite size (La) of soot particles emitted from a diesel engine were investigated. Diesel fuel and hydrotreated vegetable oil (HVO) were used. Regardless of fuel type, La varied with intake gas conditions, and the qualitative trends in its variation were consistent across both fuels.

A Study on the Combustion Characteristics of a Methanol-Diesel Dual-Fuel Engine

Kei Morita･Taiga Moriwaki (Waseda University)･Ryosuke Kogure･Takafumi Tanaka (Mitsubishi Heavy Industries Enine & Turbocharger)･Tomohiro Koga (Mitsubishi Heavy Industries)･Jin Kusaka (Waseda University)

The fundamental combustion characteristics of diesel methanol co-combustion were investigated over a wide range of conditions by the visualization experiments using a rapid compression and expansion machine. In addition, a reaction mechanism was selected based on the analysis of ignition delay and the laminar flame speed by detailed chemical kinetic calculation, and a highly accurate 3D-CFD model capable of predicting combustion under various parameter changes was developed. It was found that that excessively advanced or retarded diesel injection timing result in the deterioration of the diesel spray behavior and causes a significant ignition delay.

Effect of Biofuels on Soot emission Focusing on Hydrogen Content

Takafumi Kato･Kanta Kasugai･Ryosei Takeda･Ryoma Ohnishi･Kensei Kurita･Yoshiaki Nishijima (Aichi Institute of Technology)

In diesel engines, a higher hydrogen content in the fuel meaning a lower carbon content, which is expected to lead to soot formation reduction. Combustion tests were conducted using a single-cylinder engine. We measured that the amount of soot production against the hydrogen content in the fuel.

The effect of HVO ratio for ignition timing

Ryosei Takeda･Kanta Kasugai･Takafumi Kato･Ryoma Ohnishi･Kensei Kurita･Yoshiaki Nishijima (Aichi Institute of Technology)

Biofuels have attracted attention as a means of improving the exhaust performance of diesel engines. In particular, HVO (Hydrotreated Vegetable Oil) has a high hydrogen content due to hydrotreatment. This characteristic promotes the reaction between hydrogen in the fuel and oxygen in the air, resulting in an earlier ignition onset. In this study, we confirmed that HVO exhibits an earlier ignition timing than that of diesel fuel.

Evaluation of ignition and combustion characteristics of bio-blended fuel using a diesel engine equipped with a DPF

Minoru Tsuda･Masateru Ishida･Dai Yamanishi (National Fisheries University)･Yoriyuki Kambe (Was-inc)･Hidetsugu Sasaki (Tokyo University of Marine Science and Technology)

Since the ignition temperature of biodiesel fuel (BDF) is higher than that of diesel fuel, it is necessary to clarify its ignition and combustion characteristics. In this study, we clarified the ignition and combustion characteristics when using B5 (5% bio-blended fuel), B10, B20, and B30 as fuels in a 214kW/3101min-1 diesel engine equipped with a DPF in the exhaust system, and the effect of cerium-based fuel additives on reducing soot accumulated in the DPF (fuel efficiency improvement effect).

Effects of Fuel Physical Properties on Shape of Spray from a Diesel Nozzle

Kodai Aritomi･Keisuke Komada (Fukuoka Institute of Technology)･Shohei Yamamoto (Osaka Electro-Communication University)･Yasuyuki Takatsu (Fukuoka Institute of Technology)

The kinematic viscosity, surface tension, and density of the fuel were focused in this study, and test fuels were prepared in which only these physical properties differed. The test fuel, pressurized to 60 MPa, was injected into the atmosphere through a 10-hole injector with a nozzle diameter of 0.133 mm. The fuel spray was observed using a high-speed camera. The spray width was wider when the kinematic viscosity was low or the surface tension was low. The spray penetration was shorter when the density was high.

Nonlinear Vibration Response Modeling and Performance Prediction of Air Suspension Using Machine Learning

Yoshihiro Atsumi･Yasukazu Sato (Yokohama National University)

A vibration response model incorporating the nonlinear characteristics of an air suspension is constructed using machine learning, and a method for accurately predicting ride comfort performance is proposed. The nonlinear characteristics are separated into static and dynamic components based on design specifications and experimental data. These components are then modeled. The prediction accuracy of the proposed method is evaluated through simulations in preparation for bench testing, and its effectiveness is demonstrated.

Estimation Technique of Differential Pressure–Flow Characteristics of Shock Absorber Valves Based on Machine Learning

Haruhito Kato･Peng Lyu･Kenji Hashirayama･Naofumi Harada (Astemo)

In the early design phase of shock absorbers, it is necessary to obtain the differential pressure–flow characteristics of the valves. The characteristics are generally estimated using computer simulations. It is difficult to increase both estimation accuracy and computational efficiency since the characteristics depend on valve geometry. In this paper, we develop the machine-learning-based estimation technique that is able to address the practical problem.

A Target Characteristic Setting Method for Tires and Suspensions Using Surrogate Models and FRF-Based Substructuring

Keito Akima･Masayuki Taketani･Hideki Kawai･Hiroyuki Seino･Hirotaka Shiozaki (Mitsubishi Motors)

Road noise development is facing increasing constraints due to shortened development schedules and fuel efficiency demands, making it crucial to set appropriate component targets in the early stages when design flexibility is high. This study proposes a method using surrogate models and FRF-based substructuring to derive specific targets such as component stiffness and resonance frequency from interior noise targets.

Occupant Head Motion Estimation Using an LSTM-Based Machine Learning Model

Kenji Nishida･Chikara Kawamura･Daichi Sato･Hiroto Nishimura･Hiroaki Miyatake･Kenji Takeda･Yu Chen･Toshiaki Aoki･Kosuke Maruyama･Toru Ishikawa (Mazda)

In vehicle development, it has been challenging to quantitatively predict, at the early design stage, how changes in vehicle requirements affect occupant head motion. In this study, an LSTM-based time-series model was developed using experimental data to predict occupant head motion from vehicle behavior. A key feature of the model is its ability to account for input history. The prediction accuracy of occupant head motion under variations in vehicle behavior was evaluated, and the applicability of the model to vehicle requirement analysis was assessed.

Multi performance parametric optimization for motor using machine learning models and Robust validation

Koichi Yakawa･Ryoichi Adachi･Ryotaro Nakayama (Mazda)

In this presentation, we will introduce a method for exploring specification and the evaluation of variation factors through parametric optimization using machine learning models. In the development of electric vehicle motors,manual adjustments take time to derive specifications that resolve conflicting multi-performance issues and comprehensive verification of variation factors. We created a machine learning model based on JMAG calculation results, incorporated it into an optimization tool, and performed optimization. We also used the created machine learning model to evaluate the impact of variation factors.

Optimization of an FCEV Air Exhaust System for Flow-Induced Noise Reduction and Cost Efficiency

Jong Yeol Lee･Seung Tae Gong･Jong Seung Won (Hyundai Motor)･Hyun Soo Kim･Joon Ho Jang (SJG SEJONG)

This study investigates an optimized air exhaust silencer for a fuel cell electric vehicle to reduce flow-induced noise while improving cost efficiency. Vehicle tests identified discharge noise in the 1-3 kHz range as the primary NVH issue, originating from APC valve-induced turbulence and structural limitations of the production silencer. To mitigate this, the noise attenuation zone was relocated forward and a Helmholtz resonator-based concept was applied. Transmission loss analysis showed that the optimal design achieved up to 16.6 dB improvement in TL RMS, maintained approximately 90% gas-liquid separation, and reduced dependence on absorptive materials.

Effects of carrier frequency modulation control on the unpleasantness of inverter noise

Takuma Kasori･Masahiko Kondo･Masao Yamaguchi･Takeshi Toi (Chuo University)

Inverter noise consists of multiple pure-tone components generated by the carrier frequency and its sidebands. In recent years, carrier frequency modulation has been used to spread these pure-tone components and improve masking effects. In this study, the effects of modulation parameters, such as modulation width, on unpleasantness were quantitatively evaluated, and effective modulation conditions for reducing unpleasantness were clarified.

Adaptive Update of a Backlash Estimation Observer Based on Online Backlash-Angle Identification for Vibration Suppression in EV Powertrains

Manato Kawasaki･Noboru Sakamoto･Akira Nakashima (Nanzan University)

We propose a method to suppress vibrations in EV powertrains by online identification of the gear backlash angle and adaptive updating of a backlash estimation observer via feedback of the identified value. Numerical simulations demonstrate the effectiveness of the proposed method and provide a comparison with a conventional observer under parameter variations. The influence of identification errors on vibration estimation is also discussed.

Measurement of rattle behavior and backlash modeling in automatic transmissions

Seijun Morita･Kensuke Imanishi･Kotaro Suzuki･Ryu Chikasue･Yu Chen (Mazda)

In automatic transmissions (ATs), expanding the lock-up area or adopting a torque-converter-less structure can improve environmental and driving performance, but it also increases the risk of rattle noise. By measuring the angular velocities both sides of the backlash inside the AT, the rattle occurrence state for each driving condition were identified. Based on measurement results, the backlash model capable of reproducing backlash collision velocities was constructed.

Motor Bearing Knocking in Electric Powertrains
-(Part I - Elucidation of the Mechanism)-

Shinpei Kondo･Daisuke Kobayashi･Tsuyoshi Kozima･Hiroshi Matsuo (Nissan Motor)･Takanori Nakatani (Nissan Automotive Technology)

Although abnormal noise in electric powertrains is easily detected in electric vehicles, its underlying mechanism remains unclear. This paper focuses on knocking noise from motor bearings and, based on dynamic simulations and validation on an actual powertrain, shows that the knocking phenomenon occurs when the radial runout trajectory of the motor shaft, tilted by gear reaction forces, passes through the bearing's radial clearance.

Motor Bearing Knocking in Electric Powertrains
-(Part II - Development of the Design Method)-

Daisuke Kobayashi･Shinpei Kondo･Takayuki Asai･Shiro Kono (Nissan Motor)

Based on the shaft dynamic behavior mechanism of the electric powertrain clarified in the first report, this study proposes a design process for noise suppression through shaft dynamic behavior control. Shaft dynamic behavior analysis is incorporated as an evaluation method applicable to component design, enabling the quantitative prediction of abnormal noise. This approach enables a superior balance among cost, efficiency, and NVH performance in electric powertrains.

Equalization of Natural Frequency Spacing in Panel Design

Rui Yamada (Gifu University)･Keizo Konishi･Kunito Iida (Honda R&D)･Yuichi Matsumura (Gifu University)

When designing structures such as automobiles, the natural frequencies of each subsystem are generally separated from one another to prevent significant changes in the natural frequencies after assembly. In this study, we investigated a method to equalize the intervals between the natural frequencies of a panel-like structure without making structural modifications, by optimizing the placement of spot welds.

A method for reducing blocked force by sparse structural modifications

Tatsuki Morishita (Gifu University)･Yuki Kato (Kochi University of Technology)･Yuichi Matsumura (Gifu University)

In this study, we developed a method to reduce Blocked force by modifying the structure of the excitation subsystem to reduce the response of the passive subsystem. By employing sparse modeling, we minimized the extent of the structural modifications and reduced their impact on the whole structure. This presentation reports the results of applying the proposed method to a finite element model.

Extension of a Tire/Road Noise Model Accounting for Two Peaks of Accelerated Pass by Noise Level

Naoki Suzuki･Yoshihiro Shirahashi･Toru Yamazaki･Yukari Iwaizumi (Kanagawa University)･Masayuki Wada･Daisuke Morie (Nissan Motor)

Conventional models of tire-road noise under acceleration have mainly focused on noise generated at the tire trailing edge. In this study, the model is extended to include noise generated at the leading edge, focusing on the bimodal characteristics observed in pass-by noise during acceleration. The applicability of the proposed model was verified using multiple tires. The results show that the leading edge noise can also be modeled based on elastic energy and that the extended model is effective for evaluating vehicle exterior noise.

Development of a Technology for Enhancing Effective Felt Mass and Transmission Loss via Low-Stiffness Region Control in Automotive Double-Felt Soundproofing Materials

Kanta Kasama･Ryoji Morisaki･Shinichiro Iwai (Hirotani)

A technique for improving transmission loss (TL) in automotive double-felt soundproofing materials was developed by controlling the low spring constant region between the sound-absorbing felt and the film. Furthermore, a prototype dash insulator incorporating this technique was fabricated, and its effectiveness was validated through in-vehicle evaluation

Experimental Characterization of Vibration Properties of an MG Stator Structure with a Laminated Core and Resin Fixation Using Simplified Test Specimens

Shingo Aoki･Hiroshi Hashimoto･Yusuke Sawamura (Toyota Motor)

To achieve lean development of motor NV performance, prototype-free approaches are being pursued; however, the prediction accuracy of vibration characteristics for MG stator structures with laminated cores and resin fixation materials remains a challenge. In this study, experimental verification using simplified test specimens was conducted, focusing on the deformation behavior of laminated cores. As a result, vibration characteristics and shape effects were clarified, and high-accuracy prediction of vibration characteristics was achieved by incorporating these findings into the model.

Development of a Mixed Traffic Simulation Environment with Heavy Vehicles Incorporating a Merging Decision Model Based on Empirical Trajectories

Kenta Shintoku･Nobuhiro Araki･Tomoyo Saitou･Tushar Shrotriya (Kozo Keikaku Engineering)･Hiroyuki Furushou･Hisashi Imanaga･Hideo Nakamura (JARI)･Hiroshi Fujimoto (JAMA)

This study extracted and modeled the human merging decision-making process from empirical trajectories to evaluate natural merging behaviors in mixed traffic flows containing automated and advanced driver-assistance vehicles. Subsequently, by integrating both the mixing of heavy vehicles with distinct characteristics and a merging scene classification into the traffic flow simulation, the high-accuracy reproducibility of vehicle behaviors under actual conditions was confirmed.

Evaluation of merging support system using assumed automated driving vehicles on main lane of Highway
-(First Report) Effective penetration rate of automated driving vehicles in the system at early penetration stage-

Hisashi Imanaga (JARI)･Kenta Shintoku･Nobuhiro Araki･Tushar Shrotriya･Ryota Okazaki (Kozo Keikaku Engineering)･Hideo Nakamura (JARI)･Hiroshi Fujimoto (JAMA)

This paper proposes a merging support system assuming the widespread use of automated vehicles on highway main lanes. It involves increasing the distance between leading vehicles to facilitate merging. Traffic flow simulations confirmed that, assuming a low proportion of automated vehicles in the initial stages of adoption, this system can minimize negative impacts up to a 30% adoption rate of automated vehicles.

Evaluating Traffic Control in Pedestrian-Vehicle Mixed Spaces Using Agent-Based Simulation Considering Personal Characteristics

Shunto Araki･Hiroyuki Okuda (Nagoya University)･Kazunori Ban (Toyota Technical Development)･Tatsuya Suzuki (Nagoya University)

In pedestrian-vehicle mixed spaces, it is important to consider the impact of traffic participants' personal decision-making characteristics on traffic flow. In this study, we probabilistically modeled individual decision-making characteristics based on experimental data collected in a virtual environment, and constructed an agent-based simulation incorporating these models. Using the constructed simulation, we execute various traffic control scenarios to evaluate traffic control approaches from the perspectives of efficiency and safety.

Development of an Optimal Charging Infrastructure Deployment Model Considering the Adoption of Electric Trucks for Long-Distance Transport

Soichiro Ishii･Hirohisa Aki (University of Tsukuba)

In this study, we developed an optimal deployment model for charging infrastructure that combines dynamic wireless power transfer systems and quick charging facilities at parking areas, targeting electric trucks used for long-distance transport on expressways. Furthermore, we performed traffic simulations based on the vehicle penetration status to analyze facility deployment, charging facility use, and the impact on power load.

Promotion of Proactive Behavioral Change to Prevent Human Error
-Part 1 Longitudinal relationships between perceptual–cognitive functions and strategic driving behavior in older drivers-

Toshihisa Sato (AIST)･Hiroshi Yoshitake (Institute of Science Tokyo)･Yoshiko Goda･Masashi Toda (Kumamoto University)･Motoki Shino (Institute of Science Tokyo)

This paper describes the relationship between perceptual and cognitive functions and strategic driving behavior at two time points, one year and four years later. The study involved 106 older drivers (57 of whom were female). Structural equation modeling contributed to identifying the strategic driving behaviors where the impact of changes in cognitive function over time became evident, as well as those where the cognitive factors influencing them changed.

Promotion of Proactive Behavioral Change to Prevent Human Error
-Part 2 Analysis of Behavioral Change Processes in Older Drivers Through Collaborative Reflection-

Yoshiko Goda･Masashi Toda (Kumamoto University)･Maki Arame･Junko Handa (The Polytechnic University of Japan)･Hiroshi Yoshitake (Institute of Science Tokyo)･Toshihisa Sato (AIST)･Motoki Shino (Institute of Science Tokyo)

This study analyzed the process of safe behavioral change by combining driving data from AI-equipped training vehicles with reflective dialogue among nine older drivers. Participants collaboratively reflected on their driving characteristics and hazardous situations through group discussions. The results indicated a reduction in major driving errors, along with increased awareness of personal driving tendencies, perspective changes through interaction with others, and metacognitive reflections related to hazard prediction. This paper qualitatively examines how collaborative reflection contributes to proactive behavioral change in older drivers.

Promotion of Proactive Behavioral Change to Prevent Human Error
-Part 3 Effects of Presenting Benefits of Behavioral Change in Driving Behavior Intervention for Older Drivers-

Hiroshi Yoshitake (Institute of Science Tokyo)･Jongseong Gwak (Takushoku University)･Motoki Shino (Institute of Science Tokyo)

To promote voluntary changes in driving behavior among older drivers, a previous study proposed first-person perspective training with feedback. However, individual differences in intervention effects suggested that understanding the rationale and benefits of behavioral change may influence outcomes. In this study, we presented information on the rationale and benefits of changing driving behavior during the intervention and examined how the content of this information affected post-intervention changes in driving behavior.

Promotion of Proactive Behavioral Change to Prevent Human Error
-Part 4 Estimation of Driver's Head Pose, Gaze, and Driving Posture and Visualization of Gaze Targets Using In-Vehicle Cameras for Driving Behavior Analysis-

Ryota Ishihara･Akito Yamasaki (Meijo University)･Hiroshi Yoshitake･Motoki Shino (Institute of Science Tokyo)

Quantitative analysis of driving behavior is essential for developing assistance strategies that promote drivers' autonomous behavioral change. In this study, we propose a system that estimates a driver's head pose, gaze direction, and driving posture from in-vehicle camera images in a non-contact manner, and visualizes gaze targets by projecting the gaze direction onto the forward-view image. The effectiveness of the proposed method is demonstrated through experiments in an actual vehicle environment.

Promotion of Proactive Behavioral Change to Prevent Human Error
-Part 5 Development of a Fundamental Technology for Integrating Attention Targets Extracted via LLM-based Traffic Context Understanding with Driver Gaze Targets-

Soma Yamasaki･Akito Yamasaki (Meijo University)･Hiroshi Yoshitake･Motoki Shino (Institute of Science Tokyo)

Conventional driving behavior analysis can evaluate "what the driver looked at," but it has been difficult to address the requirements imposed by the traffic environment, namely "what the driver should have looked at." In this study, we propose a method that extracts and structures "attention targets" from road environment images using a large language model, and integrates them with the driver's "gaze targets" to quantitatively evaluate the appropriateness of confirmation behavior.

Development of Driver Education System for Calibrating Older Drivers' Self-Assessment

Motoki Shino･Shuto Inouchi･Hiroshi Yoshitake (Institute of Science Tokyo)･Ryota Fujita･Hiroto Kato (Mitsubishi Precision)

We developed a driver education system designed to calibrate drivers’ self-assessment of their driving without the involvement of an instructor utilizing a driving simulator. The system was applied to older drivers, and the results suggested that it can increase safety awareness and anxiety about traffic accidents, while improving driving behavior at intersections. The results also revealed that greater correction of overestimation through driver education was associated with greater improvement in driving behavior.

Distinction of Attention Decline Using Eye-Centering Phenomenon in Viewing Driving Video

Hiroaki Ogawa･Katsushi Asami (DENSO)･Takushi Kawamorita (Kitasato University)

The previously reported eye-centering phenomenon, in which gaze shifts toward the center of the visual field during decreased attention, has raised concerns regarding its applicability in driving environments, where forward gaze predominates. In this study, we confirmed that this phenomenon also occurs while viewing driving scenes and demonstrated its potential applicability for detecting attentional decline.

Development of an Intention Estimation Method Using Driver Gaze Behavior During Driving (First Report)

Kenta Yamamoto･Takashi Furuichi･Teru Goto･Tsubouchi Atsushi (Honda R&D)

When reaching for a cup, humans typically look at the cup before extending their hand. In this way, gaze movements precede limb movements. By exploiting this characteristic, this study aims to develop a method for estimating the trajectory that a driver intends to follow (i.e., intention) from the driver’s gaze behavior prior to the execution of driving actions. In this report, we present human gaze characteristics that are related to trajectory generation.

Analysis of Driving Behavior of Automobile Drivers During Sudden Visual Field Changes Using a Driving Simulator (Report 1)
-Investigation of a Method for Reproducing Sudden Visual Field Changes and the Effectiveness of the Blind Spot Monitor (BSM)-

Yushi Mitsumori･Daisuke Ito (Kansai University)･Hiroshi Kuniyuki (Suwa Tokyo University of Science)

Driving behavior during sudden visual field changes and the effectiveness of the Blind Spot Monitor (BSM) were analyzed through driving simulator experiments. In a scenario assuming lane changes and stopping while a vehicle was approaching from behind, drivers with higher anxiety tendencies tended to require more time to stop, and the results suggested that auditory warnings may be more effective than visual warning lights for the BSM.

Effect of Forward Field-of-View Width on Motion Sickness During Fixed Gaze Inside a Car

Masateru Amano･Kazunori Higuchi･Yosikazu Hattori (Toyota Central Reserach Laboratory)

To reduce motion sickness during in-car visual tasks, we investigated the effect of forward field-of-view restriction on motion sickness while rear-seat passengers maintained a fixed gaze within the vehicle interior. During figure-eight driving maneuvers with a maximum yaw rate of 15 deg/s, the motion sickness score (MISC) was lowest when the forward field of view within ±30° was occluded.

Effects of Foaming on Transmission Fluid for Hybrid Vehicles

Shuzo Sonoda (Honda R&D)

In hybrid vehicles, the integration of electric motors within the transmission has become widely adopted, with a single fluid being utilized for both cooling and lubrication.As higher rotational speeds raise concerns regarding shear-induced degradation of the fluid, the present study focuses on foaming behavior under such operating conditions.The differences in surface foam and entrained bubbles, depending on the type of antifoaming agent, as well as their respective effects on lubrication performance, are systematically investigated.

Study on Friction Reduction in Oil-Film Journal Bearings Using Microbubbles
-Application and Evaluation of Novel Oil Grooves-

Shodai Sakabe･Yuki Yoshimura･Yuto Yamazaki･Koki Gonda･Yuki Kawamoto･Akihiko Azetsu･Masayuki Ochiai (Tokai University)

It has been demonstrated that microbubbles reduce friction in oil-film journal bearings, where an increase in the void fraction (the volumetric ratio of the gas phase to the liquid phase) within the bearing clearance enhances the friction reduction effect. Therefore, this study investigated a novel oil groove design aimed at increasing the void fraction, and friction torque measurement experiments were conducted on a bearing incorporating this groove.

A Study on Seizure Prediction of Engine Plain Bearings Using EHL Analysis

Shinichi Sakurai･Akichika Shimizu･Motohiko Koshima (Daido Metal)

In predicting seizure of engine plain bearings, parameters such as PV value, film thickness ratio (Λ), and temperature are typically used. However, by utilizing EHL (elastohydrodynamic lubrication) calculations to evaluate a wider range of physical quantities, further improvements in prediction accuracy are expected. This study presents our research.

Relationship between Electrolytic Corrosion and Lubrication State in e-PT Sliding Components

Tomohiro Sezume･Makoto Maeda･Gou Katou (JATCO)･Shinji Koyama (Gunma University)

Electrolytic corrosion in bearings and similar components is caused by motor leakage current. This phenomenon occurs when current flows through the lubricating oil in sliding interfaces, leading to electrical discharge machining (EDM) and subsequent damage. In this study, we focused on the lubrication state and the properties of the transmission fluid to clarify their influence on electrolytic corrosion through experimental analysis.

Effect of Lubricants on Tooth Surface Damage Behavior of Gears in e-Axle Reduction Units

Takashi Yanagihara (Idemitsu Kosan)

For gears in e-Axle reduction units, where high-speed operation increases the importance of tooth surface damage, the effect of lubricants was evaluated. Based on surface observation, tooth profile measurement, and roughness measurement, differences in wear behavior and fine-scale tooth surface damage caused by different lubricants are reported.

Severity Analysis of m-LSD Differential Durability Test Using the Morrison Surface Fatigue Equation

Hwiun Lee･Daejin Kim･seonghyun Son･seungyong Bae (Hyundai Motor)

This study investigates pitting fatigue life at the cam-ring gear contact in a mechanical limited slip differential (m-LSD) with asymmetric spur gears. Using the Morrison life equation, it quantitatively compares accumulated contact fatigue damage between component-level bench tests and full-vehicle circuit driving. Two representative loading conditions were analyzed: high-load/low-differential-speed and low-load/high-differential-speed. Contact stress factors and fatigue damage were calculated for each case, and equivalent bench test cycles were derived from actual circuit driving distances.

Auxiliary Brake Apparatus by Air Compression and Release for Stop of Heavy FCV Regenerative Brake (6th report)
-Proposal of a Rotary Vane Mechanism for Compact Design-

Ko Amada･Daiki Fujita･Mimi Tsuchiya･Toshinori Fujita･Takashi Shibayama (Tokyo Denki University)

In our previous reports, we proposed a simplified auxiliary brake based on an air compression and release system to be used in situations where regenerative braking in FCV trucks is unavailable. The previous design employed an axial piston mechanism, which required converting rotational motion into reciprocating motion, thereby imposing limitations on compactness. In this report, we propose a rotary vane mechanism for improved compactness and present its characteristics.

Development of a Power Transmission Characteristics Testing Machine for High-Speed, High-Output, and High-Reduction-Ratio Traction Drives

Natsuki Morita･Takeshi Yamamoto (Tokai University)

To evaluate the performance of traction drives, a power-circulation testing machine was developed to enable measurements at 50,000 rpm and 50 kW. This machine overcomes facility constraints and achieves traction coefficient measurements under these specific high-speed and high-output conditions. Furthermore, in tests under high reduction ratios, it was confirmed that the traction coefficient could be successfully measured without any reduction.

Electric Control of a CVT for Motorcycles Using a Self-Locking Reduction Mechanism

Genjiro Ueda･Tatsuhito Aihara (Hosei University)

An electric control method for a CVT for motorcycles using a self-locking reduction mechanism and a motor is proposed. The pulley position is controlled by the motor to achieve rapid shifting and high efficiency. In addition, the self-locking function enables the pulley position to be maintained without power consumption. This presentation reports the mechanism configuration, operating principle, and shifting characteristics of the proposed system.

Powertrain Vibration Suppression via the Integration of Domain Randomization-Based Deep Reinforcement Learning Control and Model-Based Control

Heisei Yonezawa･Ansei Yonezawa･Itsuro Kajiwara (Hokkaido University)

The design of control systems for powertrains requires consideration of nonlinearities and uncertainties in dynamic characteristics. In recent years, deep reinforcement learning has attracted considerable attention as a promising approach; however, learning inefficiency and policy conservativeness remain significant challenges. To address these issues, this study proposes a method for assisting domain randomization-based deep reinforcement learning by introducing a model-based controller that ensures baseline performance.

Development of a Mode-Adaptive Shift Control Optimization Method for Fuel Cell Garbage Trucks with Multi-Layered Operating Modes

Yida Bao･Jiakai Gao･Xiang Zhang･Jiachen Xi･Yiyuan Fang･Wei-Hsiang Yang･Yushi Kamiya (Waseda University)

Fuel cell garbage trucks exhibit complex collection-and-driving patterns with wide-ranging performance requirements, making it difficult for a single shift map to maintain optimal operation. This study proposes a multi-layered operation-mode-based shift map considering motor torque limit characteristics and regenerative braking. Bayesian Optimization is applied to jointly optimizes gear ratios and shift maps under an integrated objective combining energy efficiency, dynamic performance, and drivability. Simulation results on representative duty cycles show that, compared with conventional fixed shift maps, the proposed approach improves both energy efficiency and dynamic performance while preserving drivability.

Proposal of a CVT Shift Map for BEVs Based on Optimal Control Methods

Hanqing Zhao･Yasuo Moriyoshi･Tatsuya Kuboyama (Chiba University)

For EV CVT control, shift maps are generally designed empirically, and their optimality has not been sufficiently investigated. In this study, optimal CVT ratios under various driving conditions were calculated using an optimization method, and the differences from the conventional CVT map were analyzed. In addition, correction regions were classified using a decision tree, and correction maps for each region were constructed to investigate a method for improving conventional CVT shift maps.

Development of a Virtual Performance Evaluation Model for New Multi-Mode Hybrid Powertrain System with RCP-HIL Validation

Myeong-Won Seo･Dohyun Park･Janghyeok Won･Beomho Lee･Taeho Park･Deokjin Kim (Korea Automotive Technology Institute)

This study presents a virtual performance evaluation model for a multi-mode hybrid powertrain comprising a 1.6L GDI engine, P1/P3 electric motors, and a dog-clutch 2-speed transmission. Three driving modes - EV, Series HEV, and Parallel HEV - are supported through a multi-controller architecture (HCU, TCU, ECU, MCU, BMS, BCU). Plant and controller subsystems are separated into non-virtual blocks, enabling RCP-HIL deployment via dual Speedgoat machines over CAN bus. All performance targets were met: (FTP-75, HWFET), 0-100 km/h in 10.00 s, EV grade ability 39.14%, and maximum speed 168.7 km/h.

Analysis of Abdominal Injury Mechanisms in Frontal Sled Simulations Using a Human Body Model

Yu-Ki Higuchi (JARI)･Mitsutoshi Masuda (JAMA)･Fusako Sato (JARI)

Abdominal injuries are a critical injury outcome for reducing fatalities and serious injuries in road traffic crashes; however, assessment methods using anthropomorphic test devices (ATDs) have not yet been sufficiently established. Toward the development of abdominal injury assessment procedures, this study analyzed the ITARDA Micro Data, an in-depth accident investigation database in Japan, to identify frontal crash configurations and abdominal injury patterns. The associated injury mechanisms were then investigated through frontal sled simulations using the THUMS AF05 human body model.

A Human Body Model Based Sensitivity Analysis of Belt Routing Conditions in Frontal Impact Simulation

Kaito Nishimura･Takashi Yoshida･Shigeru Kotama･Nozomi Saito (Tokai Rika)

This study compared occupant responses under a standard belt routing condition and multiple alternative belt routing conditions in frontal impact simulation using the THUMS human body model under identical analysis conditions.

Analysis of Pelvic Rotation in Human Body Model During Frontal Impact

Toshiharu Azuma･Yuqing Zhao･Koji Mizuno (Nagoya University)･Kei Nagasaka･Takahiro Suzuki･Idemitsu Masuda (Suzuki Motor)

In frontal impacts, rearward pelvic rotation can cause the lap belt to slip off the pelvis, increasing the risk of submarining. To investigate this phenomenon, finite element simulations of rear-seat sled tests under frontal impact conditions were conducted to analyze the pelvic rotation that occurs under lap belt restraint. The moment time histories around the pelvic center of gravity were compared using human body models (THUMS) of an average male and a small female, clarifying the characteristics of the rotational behavior attributed to pelvic shape.

Prediction of the Occupant Lower-Extremity Injury Criterion (Tibia Index) in Frontal Collisions Using Machine Learning

Seiya Tanamoto (University of Yamanashi)･Kei Nagasaka･Idemitsu Masuda (Suzuki Motor)･Yuta Yokoyama (Diver Technology)･Hirofumi Sugiyama (University of Yamanashi)･Shigenobu Okazawa (University of Yamanashi/Diver Technology)

Lower-extremity injuries sustained by occupants in frontal collisions are difficult to predict because vehicle deceleration and dashboard deformation are intricately correlated. In this study, a machine learning model is developed to estimate the occupant lower-extremity injury criterion (Tibia Index) using dashboard deformation modes and acceleration pulse inputs in sled simulations. In addition, the influence of analysis cases on prediction accuracy is investigated. Furthermore, the validity of the proposed method is evaluated through comparison with numerical simulation results.

Relationship between the shape of the front of a passenger vehaicle and its energy absorption characteristics

Keisuke Fukuyama･Takahiro Isshiki･Koji Mikami (JARI)

In traffic accident analysis, energy absorption distribution diagrams are used to calculate the deformation energy of vehicles. Existing distribution diagrams show room for further improvement in their ability to adapt to the diverse front-end shapes of vehicles in recent years. To address this issue, this study clarifies the relationship between the front-end shape and energy absorption characteristics of recent vehicles.

Effectiveness Evaluation of an Age-Adjusted D-Call Net Algorithm for Fatal and Severe Injury Prediction

Shizue Katsumata･Noboru Tanase･Takahiro Andoh (Toyota Motor)･Mayu Ishii (Institute for Traffic Accident Research and Data Analysis)

In the current operation of D-Call Net, the fatal and severe injury rate is calculated assuming an occupant age of 65 years. In this study, accident data are linked with D-Call Net notification data to investigate the actual age distribution of occupants involved in accidents and its impact on injury severity estimates.

Aerodynamic Development of Solar Car Considering Actual Flow Characteristics

Masato Ogawa･Takamasa Ninomiya･Kota Fukuda (Tokai University)･Hiroshi Tanaka･Hiromune Kanamori (Toyota Systems)･Kouhei Sagawa･Hideki Kimura (Tokai University)

Tokai University participated in many world solar car challenges. Top teams carried out aerodynamic development the state-of-the-art CFD technologies. The consideration of actual flow characteristics is crucial for the aerodynamic development of solar cars since the challenges are held in public roads. Tokai university solar car team has carried out aerodynamic development considering actual flow characteristics. In this presentation, outline of our aerodynamic development based on actual flow characteristics will be introduced.

Effect of slant angle and Reynolds number on regimes of flow around Ahmed body – difference with turbulence models

Shunta Fukuoka･Itsuhei Kohri･Suguru Shiratori (Tokyo City University)

Regimes and drag coefficient (CD) of flow around the Ahmed body may drastically change depending on the slant angle. To clarify the range where these steep CD changes take place, a series of CFD simulations is carried out using RANS turbulence models. The range of Reynolds number and slant angle for flow regime change is found to be different depending on the turbulence model used.

Aerodynamics shape optimization based on VAE and PINN - hybrid SDF and point-cloud method

Kaho Hikita･Suguru Shiratori (Tokyo City University)

In aerodynamic shape optimization, conventional methods, which require re-meshing, take huge computational cost. Our research group has proposed mesh-free approach, where the shape is parameterized by latent space based on VAE and aerodynamic drag is evaluated by PINNs. In this study, we propose a new shape representation using hybrid of SDF and point-clouds. Validations are conducted for two-dimensional airfoils.

A Comparative Study of Airflow Around a Vehicle During On-Road Driving and on a Chassis Dynamometer

Daisuke Kawano (Osaka Sangyo University)･Souma Iiboshi (Osaka Sangyo University (Currently, Daihatsu Motor))･Kazuki Aoyama (Osaka Sangyo University)･Toshimichi Takahashi (Meidensha)

Since airflow around a vehicle significantly affects its performance, chassis dynamometers need to reproduce airflow during on-road driving. In this study, airflow on a chassis dynamometer was compared with that during on-road driving by simultaneously measuring airflow velocity at multiple points around the vehicle. In addition, the factors causing the differences in these airflows were analyzed using CFD.

Overview of the Catesby Aero Research Facility (CARF), a Tunnel-Based Aerodynamic Proving Ground

Hiroshi Shimoyama･Hiroki Nagano･Satoshi Yoshizawa･Wataru Kato･Keiichi Watanabe (SUBARU)

The Catesby Aero Research Facility (CARF) is a tunnel-based aerodynamic proving ground put into operation in 2019 with investment from SUBARU through its corporate venture capital, and its facility characteristics and measurement technologies are presented. A 2.7 km straight track converted from a former railway tunnel enables continuous coast-down testing to very low speeds, providing higher repeatability than outdoor testing. The facility is expected to bridge the gap between CFD, conventional wind tunnel testing, and on-road testing.

Dynamic Aerodynamic Forces Generated by Vehicle Motion and Their Effects on Vehicle Motion
-Full-Scale Vehicle Excitation Tests in a Wind Tunnel-

Kazuhiro Maeda･Mitsuru Sugimoto･Yasuhiro Endo･Akinao Yamamoto (Toyota Motor)

To investigate the effects of aerodynamic devices aimed at improving vehicle dynamic performance, we focused on dynamic aerodynamic forces generated by vehicle motion rather than relying solely on steady aerodynamic forces. Full-scale excitation tests were conducted in a wind tunnel using a vehicle. The results showed that the oncoming flow makes the front of the vehicle less responsive to excitation while making the rear more responsive. In addition, when the flow becomes disturbed, the vehicle tends to move less easily, whereas flow rectification increases its ease of motion. These findings confirm the influence of dynamic aerodynamic forces on vehicle motion.

Wind Tunnel Evaluation of Combined Active Aerodynamic Systems on a CUV-type EV

Dong Ha kim･Hak Lim kim･Hong Hee lee･Jin Young youn･Su Bok kim･Suk Bom son･Woo Jae Kwon･Ju Wan Han･Woo Yul Baek (Hyundai Motor)

This study investigates the combined aerodynamic effects of three active systems Active Air Skirt, Active Rear Diffuser, and Active Spoiler Module on a CUV-type EV through wind tunnel testing. Results confirm a total drag coefficient improvement of delta Cd 0.023 versus baseline, with negligible interaction between systems, enabling linear superposition for aerodynamic performance prediction. These findings serve as fundamental data for the development of effective combination and control strategies for EV active aerodynamic systems, ultimately contributing to improved energy efficiency in next-generation EVs.

Development of Truck Aerodynamic Technologies to Achieve Carbon Neutrality in the Logistics Sector

Yuta Hino･Yusuke Kitazawa･Takafumi Makihara (Toyota Motor)

The logistics sector is a key area for achieving carbon neutrality, and reducing the aerodynamic drag of trucks is an effective approach to improve fuel efficiency and cut CO₂ emissions. This study applied aerodynamic knowledge from passenger vehicles to a truck and evaluated drag reduction potential of each area using wind tunnel tests and CFD analysis. And based on truck-specific constraints, more practical aerodynamic measures were proposed. These measures demonstrated weight and cost-effective aerodynamic improvements for trucks, also achieving drag reduction without compromising other performance.

An Inverse Design Method Considering Design Constraints for Automotive Aerodynamic Development

Yusuke Yoshinaga･Takuya Yabu･Naoki Hamamoto･Yasuhiko Okutsu･Norimasa Hashimoto (Mitsubishi Motors)

In the contemporary automotive industry, there is an increasing demand to deliver high-quality vehicles to customers within a shorter development period. To shorten the development period, an inverse design approach based on a statistically constrained PCA space incorporating design knowledge is proposed. Under constraints that account for design freedom, shape candidates expected to improve aerodynamic performance are generated efficiently. By enabling direct exploration within feasible design regions, trial-and-error iterations are reduced, and more effective design exploration is facilitated. As a result, the design quality of early-stage aerodynamic performance is improved, contributing to a shorter development period.

Damage assessment of cyclists collided by high-velocity runaway vehicles
-Risk assessment between high-velocity runaway vehicle and bicycle collision from statistical accident data analysis-

Yasufumi Sekine (Fukuyama University)

When discussing the dangers of high-velocity runaway vehicles, the potential for causing personal injury to victims cannot be ignored. This study analyzed the relationship between vehicle collision velocity and the fatal or serious injury rates among cyclists using traffic accident statistics. Based on these analysis results, the author attempted to clarify the risk (the injury level of cyclists) of collisions between bicycles and high-velocity runaway vehicles.

Validation of the Traffic Offence Traits Scale (TOTS)
-An Examination Using Cognitive Tasks-

Masae Kojima (Nagoya University)･Kojiro Shojima (National Center for University Entrance Examination)･Kazuko Okamura (National Research Institute of Police Science)･Chieko Nishizawa･Shota Matsubayashi･Kazunori Ban (Toyota Technical Development)

This study examines the validity of the Traffic Offence Traits Scale (TOTS), a self-report measure developed for risk assessment of offending traits. Building on previous studies confirming its 7-factor, 24-item structure, we verify that TOTS factors correspond to objective performance-based measures. A sample of general drivers will complete TOTS alongside three cognitive tasks via web panel survey: the Balloon Analogue Risk Task (BART) for risk-taking, the Iowa Gambling Task (IGT) for decision-making, and the Stop-Signal Task (SST) for response inhibition. Significant associations between TOTS factors and corresponding cognitive measures will demonstrate TOTS as a valid tool for traffic offence risk assessment.

Educational Policies Designed for Traffic Offenders: Analysis of Traits and Behavior

Chieko Nishizawa･Shota Matsuayashi (Toyota Technical Development)･Masae Kojima (Nagoya University)･Takuma Yamaguchi･Kazunori Ban (Toyota Technical Development)

Conventional educational programs for traffic offenders may not be effective for all individuals, because the programs are applied regardless of offender traits. Our goal is to develop more effective educational policy for traffic offenders. This study investigates appropriate feedback methodology as a preliminary step This paper reports the results of analyses of offender traits and behavior conducted to support the design of such feedback.

Study on Electric Kick Scooter Accident Analysis Using ITARDA Macro Data and TUAT Drive Recorder Data

Toru Kiuchi (ITARDA)･Masami Aga (Tokyo University of Agriculture and Technology)･Mayu Ishii (ITARDA)･Yukiko Ookita･Masao Nagai (Tokyo University of Agriculture and Technology)

Since July 2023, persons aged 16 and older have been permitted to ride electric kick scooters without a license. The National Police Agency’s accident statistics database, revised in 2022, added “stand-up electric vehicles” to the “Vehicle Type” category, and a further revision in 2024 added “specified small mopeds”. The authors attempted to examine electric kick scooters’ accident situation using ITARDA macro data from 2023 and 2024.

Investigation of Impact Behavior of Electric Scooter Riders in Head-on Collisions with Automobiles

Ryo Oga (Japan Safe Driving Center)

Research on electric scooter collisions using moving vehicles is scarce. This report details a head-on collision experiment between a moving automobile and a stationary electric scooter to verify rider impact behavior. Results showed the rider rode up onto the hood and struck the windshield. Due to a higher initial body position than pedestrians from the step height, the rider's hood override increased. Although the handlebar is at waist height, the stem fractured at an impact speed of 30 km/h, suggesting the handlebar minimally affects rider impact behavior.

Who Benefits from Which Driving Assistance? A Large-Scale Cross-Sectional Study on the Psychological Effects of Driving Assistance

Yoh Yamazaki (Mazda/Hirosaki University)･Nanae Michida･Masanori Honda･Hiromune Obayashi･Yosuke Furuya (Mazda)･Yoshinori Tamada･Ken Itoh･Tatsuya Mikami･Koichi Murashita･Shigeyuki Nakaji (Hirosaki University)

Driver assistance tailored to individual driver characteristics is essential for safe and comfortable driving. In this study, approximately 900 participants were classified into four groups based on driving attention ability and driving self-efficacy. We investigated the psychological effects of three types of driving assistance designed to support different cognitive functions. The results showed that the effectiveness of driving assistance differed depending on driver characteristics.

Effect of relative hood leading-edge height on torso injuries based on pedestrian in-depth crash data

Tsukasa Goto･Susumu Ejima (SUBARU)

This study examined the relationship between the vehicle front-end height relative to the pedestrian waist and hip and pedestrian torso injuries using pedestrian in-depth crash data in Japan. The results show that as the relative front-end height increases, the proportion of accidents with AIS 2+ injuries to the pedestrian chest, abdomen, and pelvis increases. This study shows detailed results, causes of this trend, and influence on pedestrian protection.

Analysis of Pedestrian Chest Injury Mechanisms in High-Hood SUV Impacts
-Change in Whole-Body Kinematics of THUMS Induced by Vehicle Reaction Forces-

Yojiro Iizuka (Toyota Motor)･Sora Ueki (Meitec)･Junji Kawashima･Hiroaki Imai･Mitsuhiro Hamada･Yuuji Nakane (Toyota Motor)

To clarify the mechanism of pedestrian chest injury in high-hood SUV impacts, a crash simulation was conducted based on the THUMS pedestrian model. Chest deflection was found to depend on thoracic impact velocity induced by bumper reaction forces transmitted through the pelvis support, whereas rib strain was primarily influenced by direct hood reaction forces acting on the thorax. These findings indicate the critical importance of vehicle reaction forces in determining pedestrian chest injury.

Development of an injury prediction algorithm using GIDAS for pedestrians in Europe

Yasuaki Gunji･Takashi Hasegawa (Honda R&D)･Suguru Yoshida (SGR Consulting)･Shigeru Tominaga (Nihon University)

This study developed an injury prediction algorithm for an Advanced Automated Collision Notification (AACN) system targeting pedestrian accidents in Europe. Using the GIDAS accident investigation database, the algorithm was developed by using collision speed and age of pedestrian as risk factors in regression analysis. As a result, the algorithm achieved a level of accuracy useful for emergency medical response assessments, predicting the probability of MAIS score of 3 or higher.

Accuracy Enhancement of CAE Simulations for Pedestrian Collision Accidents in Medical–Engineering Collaboration

Mie Tokuyama･Takahiro Andoh･Koji Onishi･Noboru Tanase (Toyota Motor)･Toru Kiuchi･Takehiro Tsuji (Institute for Traffic Accident Research and Data Analysis)

Medical–engineering collaboration aims to reduce fatalities and injuries by elucidating injury mechanisms through the integration of engineering analyses, such as traffic accident scene investigations and vehicle damage analyses, with medical diagnostic information. By further incorporating CAE-based simulations, more detailed analyses can be achieved. In this study, to improve simulation accuracy, the effects of human body model height and weight distribution on kinematic behavior were investigated using actual pedestrian accident cases. Pedestrian motion was quantitatively evaluated using an image-based 3D matching

Relative Position of a Pedestrian After Collision With Respect to the Vehicle's Stopping Position

Mototsugu Suzuki･Tetsuya Nishimoto (Nihon University)･Tomokazu Motomura (Nippon Medical School)

This study examined the relationship between the vehicle’s final stopping position and the pedestrian’s fall location in pedestrian accidents. Although the analysis was limited to approximately 18 real-world cases, the distances from the vehicle’s stopping position were identified. These findings are considered to provide fundamental information for utilizing in-vehicle cameras in emergency medical care.

Mechanisms of injury among cyclists and the influence of body center of gravity, as indicated by fatal injuries to pedestrians

Shinichi Ishii･Yasuo Ono (Chiba Pref. Police H.Q.)

In response to the urgent challenge of significantly reducing the number of traffic fatalities, as outlined in the 12th Basic Plan for Traffic Safety, we identified the mechanisms specific to cyclists by using the mechanisms of fatal injuries among pedestrians as a reference. The decisive factor distinguishing the injury mechanisms between cyclists and pedestrians was the vertical offset of the body’s center of gravity relative to the front edge of a car’s engine hood.

a Study on the Effect of Piston stiffness on Pin Rotation in a Diesel Engine

Kentaro Seki･Akemi Ito (Tokyo City University)･Yorimasa Tsubota･Junichi Miwa (Isuzu Motors)

To elucidate the rotational generation mechanism of full- floating piston pins with superior anti-seizure properties, the torque for pin rotation was measured using a newly developed testing apparatus. The effect of the stiffness of the pin boss bearing of a piston was investigated. It wasfound that pistons exhibiting low structural stiffness generate insufficient rotational force. Furthermore, the tests demonstrated that uneven contact resulted from bearing deformation were key factors that significantly impede proper pin rotation.

Oil Film Distribution and Skirt Friction Loss in the Concave Created by Piston Skirt Profile or Pattern Coating

Junpei Oshima･Kenta Sato･Hisanobu Kawashima･Hidekazu Suzuki･Tsuneaki Ishima (Gunma University)

The FMEP reduction of the skirt with the concave on the sliding surface has been estimated by calculations. Pistons with the concave in skirt profile were tested. The distribution of the oil film in the concave area was observed, and the process of oil inflow into the concave area was investigated. The skirt FMEP calculation was carried out using the results of obtained oil film distribution in the concave. The concave area has an effect of reducing skirt FMEP.

The effect of piston skirt lubrication on piston performance by modified piston shape

Kunihiko Kobayashi･Kenta Hayashi･Toshio Kobayashi･Hiroki Kosaka･Wataru Sakurai (Art Metal Mfg.)

The lubrication of the piston skirt, which moves in contact with the cylinder bore, is known to affect friction and vibration transmission to the cylinder block. In this study, when we change the lubrication of the piston skirt by modifying the stiffness and profile of the skirt, we investigate the effect of skirt lubrication on piston performance. And based on these results, we examine design guidelines to ensure the required lubrication.

Smoothing of Anodic Oxidation Film on Piston Top Ring Groove

Haruhiko Murakami･Masahiro Fujita･Shinya Suzuki (Suzuki Motor)

This study investigates the effect of smoothing the anodic oxide film on piston top ring grooves to reduce particulate number (PN) emissions immediately after cold start in direct-injection gasoline engines. Engine tests reveal a strong correlation between groove surface roughness (Ra, Rpk) and PN emissions, suggesting that roughness reduction effectively mitigates PN generation. We also confirmed that the superimposed AC/DC anodic oxidation method forms a more homogeneous film than the conventional DC method. Furthermore, we propose an ultra-low-pressure shot blasting technique aiming at mass-production applicability, which successfully reduces Ra and Rpk. This process improves oil behavior, demonstrating significant potential for suppressing PN emissions.

A Study on the effect of the Anodized Coating in the Piston Top Ring Groove on the Running-in Process and Oil Consumption

Ryuto Furumizo･Shunsuke Ito･Akemi Ito (Toyko City University)･Masahiro Fujita･Haruhiko Murakami (Suzuki Motor)

Anodized coating is applied to the piston top ring groove to prevent wear. The coating is also expected to promote early running-in and reduce PN. In this study, the effects of properties of the coating on oil consumption, which is a substitute characteristic of PN, and running-in process were investigated.

Observation of Land Oil Distribution to Elucidate Upward Oil Transport Pathways

Ryo Takenaka･Kenta Sato (Gunma University)･Noriaki Ida (Mitsubishi Heavy Industries)･Hisanobu Kawashima･Hidekazu Suzuki･Tsuneaki Ishima (Gunma University)

The oil distribution on the piston lands area was visualized to clarify the dragging oil flow phenomena by using a test engine with transparent sapphire cylinder. The tests were carried out under conditions of both 2-piece and 3-piece oil rings, as well as top rings with different gaps. The oil flow is primarily affected by the accumulated oil on the piston land area, while the ring specifications have a relatively less significant influence on it.

Study on In-Cylinder Thermal Barrier Coatings and Evaluation/Analysis Techniques for Reducing Cooling Losses
-(Third Report) Evaluation of Thermal Properties of Thermal Barrier Coatings II-

Haruka Abe･Kentaro Shinoda･Koichi Kinoshita･Yomonori Urushibara･Megumi Akoshima･Eishi Kubota･Mitsuharu Oguma (AIST)

This study aims to reduce cooling losses and improve engine thermal efficiency by fabricating a thermal barrier coating applicable to pistons using the hybrid aerosol deposition method developed at the National Institute of Advanced Industrial Science and Technology (AIST). In this report, we describe the development of a new thermal barrier coating with lower thermal conductivity than that presented in the second report, and we present the results of evaluating its thermal conductivity characteristics.

Chemical State and Structural Evolution of Metal-Containing Additives in Engine Oil under Different Operating Conditions

Masahiro Kunisu･Xi Li･Daisuke Murata･Sachi Nakashima･Tatsuya Tominaga (Toray Research Center)

X-ray absorption fine structure (XAFS) analysis was applied to metal-containing additives in engine oil for fresh oil, oil after normal operation, and samples subjected to different conditions. Differences in chemical states and local structures depending on usage conditions were identified for the target elements. Under specific conditions, an increase in components exhibiting ionic-like behavior, possibly associated with coordination by water molecules, was observed. These results indicate that the local chemical environment of metal-containing additives can vary significantly with operating conditions.

Friction Reduction Technology for Engine Journal Bearings Based on Oil Film Shear Stress

Motohiko Koushima･Mari Naga･Hiroshi Itoigawa･Tadamichi Tamura･Erina Yasuda (Daido Metal)

Friction loss reduction in engine bearings was investigated by focusing on oil film shear stress. Experiments were conducted using a newly designed test rig. The results indicate that optimization of bearing surface properties is effective in reducing friction loss under hydrodynamic lubrication conditions.

Development of a Friction Evaluation Method under Actual Operating Conditions and Friction Reduction in the Crankshaft System

Kazunori Toida･Takashi Koyama･Makoto Okawa･Teru Ogawa (Toyota Motor)

In automotive internal combustion engines, the indicator diagram methodology is widely used to evaluate friction under the working load of in-cylinder pressure; however, its measurement accuracy remains limited. To address this issue, a practical boosted-motored friction methodology was developed. Friction reduction approaches for the crankshaft system derived from analysis were validated using the developed methodology.

Experimental Study on Driver State Changes with Eyes-off Function in Traffic Jam Pilot

Takemi Tsukada･Hiromu Sato･Ryuta Yonemitsu (Honda R&D)･Motonori Ishibashi･Yukiyo Kuriyagawa (Nihon University)

This study investigated the effects of the Eyes-off function in traffic jam conditions through field testing on public roads. Compared with the hands-off function, changes in driver state were evaluated using subjective assessments and physiological indicators. The results clarify the effects relative to hands-off driving, differences in driver state characteristics, and provide insights for enhancing the value of driver assistance systems.

A Density-Estimation ACC Strategy from an Empirical Traffic Flow Relation

Yoshiaki Irie･Tomoaki Morimoto (Toyota Motor)

The mechanisms of traffic congestion have conventionally been investigated within transportation engineering. Aiming at the development of advanced vehicle control systems, this study analyzes the congestion mechanism in detail from a microscopic (individual vehicle) perspective and explores its integration into ACC algorithms.

Effectiveness of Photogrammetry-Based Three-Dimensional Modeling for Post-Crash Test Vehicle Inspection

Toru Hashimoto･Azusa Nakata (Honda R&D)

Post-crash test vehicle inspection is generally based on physical vehicle confirmation. However, it involves significant time and space constraints, which can make information sharing and re-examination among stakeholders difficult. In this study, a photogrammetry-based three-dimensional modeling method was applied to vehicles after crash tests, and its effectiveness for post-test inspection was evaluated. After organizing the image acquisition conditions and model generation procedure, the reproducibility of the generated three-dimensional models and the visibility of vehicle damage phenomena were assessed. The results confirmed that, compared with conventional photographic records, the proposed method improves the understandability of damage modes and the shareability of inspection information. This method has the potential to enhance the post-crash test vehicle inspection process.

Experimental Study on Collision Avoidance Performance of the System during Rapid Approach of Another Vehicle while the Driver is Using Advanced Driver Assistance Systems (ADAS)

Toru Kojima･Yuki Manabe･Akihiro Abe･Mamoru Takushima･Koichi Kitada (NALTEC)

As representative scenarios in which another vehicle rapidly approaches while the driver is using Advanced Driver Assistance Systems (ADAS), vehicle experimental tests on sudden deceleration of a lead vehicle and cut-in maneuvers were conducted. Based on the experimental results, the collision avoidance performance of the system, including the activation of the Advanced Emergency Braking System (AEBS), was analyzed.