Advanced Process for the Highly Efficient Conversion of FT Synthetic Crude Oil to FT Gasoline and Diesel for Automotive Use

Kenichi Okamoto･Noriaki Ohmori･Hiroshi Kisai･Akio Imai･Kazuyuki Morita･Mitsunori Tabata (Japan Petroleum and Carbon Neutral Fuels Energy Center)･Natsuki Hamada･Kazuhito Sato (Cosmo Oil Co., Ltd.)

The wax fraction of synthetic crude oil obtained using FT catalysts was post-processed, and the energy consumption and octane number of the resulting gasoline were evaluated. Additionally, the quality characteristics of synthetic crude oil produced using a hybrid catalyst, combining FT catalysts with a bifunctional catalyst for wax cracking, were analyzed. The potential for efficiently converting the synthetic crude oil into high-quality automotive gasoline and diesel was also investigated.

Investigation of Engine Combustion Characteristics of Fischer–Tropsch-Derived Gasoline

Kohei Kuzuoka･Mitsuharu Oguma (AIST)･Kenichi Okamoto (Japan Petroleum and Carbon Neutral Fuels Energy Center)

Gasoline engines require fuels with high knock resistance, typically indicated by a high octane number. However, fuels derived from Fischer–Tropsch (FT) synthesis often exhibit low octane numbers, which limits their direct applicability. In this study, the sensitivity of engine performance to changes in octane number was quantified, and the combustion characteristics of an engine fueled with post-processed synthetic fuel were evaluated.

Optimization of Diesel Injection Parameters for the Compatibility of Oxymethylene Dimethyl Ether (OME)

Shusuke Tanaka･Kaito Konno･Jiang Zijian･Hiroya Yamamoto･Masatoshi Tasima (Graduate School of Engineering, Hokkaido University)･Gen Shibata･Hideyuki Ogawa (Hokkaido University)

Oxymethylene dimethyl ether (OME) is effective in reducing smoke and shortening afterburn; however, its low calorific value necessitates optimization of the fuel injection system. In this study, injection parameters—namely injection pressure, nozzle hole diameter, and the number of holes—were varied to evaluate their effects on engine performance using OME blended fuel. Combustion images were also analyzed using a rapid compression and expansion machine to investigate spray and flame development, aiming to identify suitable injection conditions for stable and efficient combustion.

Effect of Distillation Characteristics of Synthetic Liquid Fuels on Diesel Spray Combustion

Hiroya Yamamoto･Masatoshi Tashima･Shusuke Tanaka･Kaito Konno (Graduate School of Engineering, Hokkaido University)･Gen Shibata･Hideyuki Ogawa (Research Faculty of Engineering, Hokkaido University)

In diesel spray combustion, fuel volatility and ignitability influence both the lift-off length and liquid-phase penetration. In this study, Fischer–Tropsch (FT) diesel was fractionated into four components ranging from light to heavy fractions. Using a Rapid Compression and Expansion Machine (RCEM), spray behavior was visualized and the lift-off length at ignition was measured. The effects of distillation　characteristics on spray formation and combustion were then analyzed to clarify how volatility influences the combustion process of synthetic diesel fuels.

Study of engine combustion in cold start in use of rich methanol blended fuel

Tetsuya Ohira (Aichi University of Technology)･Keisuke Ito･Makoto Kaneko･Hidenori Fujii･Naoyuki Suda･Yoshinari Ninomiya (Suzuki Motor)

Use of methanol is under study as carbon neutral fuel for engines. However, its properties, such as, boiling point, latent heat can be difficulties with engine combustion in cold start. In this study, with a spark ignited engine for production motorcycle, fuel vaporization in intake port, temperature distribution around engine parts, exhaust and crankcase gas emissions were investigated together with combustion stability in cold start. It was found that deep temperature drop and poor fuel vaporization in intake port caused worse combustion stability after engine start. Measured data could also suggest engine oil dilution as the other issue.

Effects of Ethanol on Combustion in Super Lean Burn Engine

Kenji Sugata･Naoyoshi Matsubara･Ryota Yamada･Koji Kitano (Toyota Motor)

In order to reduce WtW CO2 emissions from vehicles equipped with internal combustion engines, it is important to use bioethanol effectively. Lean burn engine is known as one of the means of improving thermal efficiency. In this study, the effects of ethanol blending on thermal efficiency, knocking, emissions, and combustion duration within the range of λ=1 to 2.5 are analyzed.

Alcohol Diffusive Combustion Technique as an Alternative Diesel Combustion (Third Report)
-Requirements of the diesel pilot injection for ethanol diffusive combustion by dual fuel injector-

Yoshifumi Wakisaka･Kenji Fukui･Teruaki Kondo･Yoshiyuki Mandokoro･Kazuaki Nishikawa･Takayuki Fuyuto (Toyota Central R&D Labs.)･Kenji Date･Yusuke Ueda･Satoshi Sugawara (DENSO)

Alcohol fuel, namely methanol and ethanol, are promising fuel for diffusive combustion in heavy-duty diesel engines, while they are difficult to self-ignite. In this study, a prototype dual-fuel injector that injects diesel fuel as an ignition source from the same nozzle with ethanol was developed. Requirements for the pilot injection with a high diesel fuel content to ignite the main injection with a high ethanol content were identified experimentally by in-cylinder observations and a single-cylinder direct injection diesel engine test.

Effects of Port Fuel Injection of Liquid Annmonia on Intake Air Mass and Combustion Characteristics in a Spark-Ignition Engine

Mitsuaki Ohtomo･Hideaki Masui･Hiroshi Miyagawa (Toyota Central R&D Labs.)･Norinosuke Nakatani･Tadashi Takeuchi (Toyota Industries Corporation)

The effects of intake air cooling with the latent heat of port-injected liquid ammonia in a spark-ignition engine on intake air mass and combustion characteristics were investigated using simulations and experiments. A decrease in intake air temperature resulted in an increase in intake air mass and improved IMEP, without leading to longer combustion duration or an increase in unburned ammonia. Furthermore, it was found that the increase in intake air mass varied depending on the injection timing of the liquid ammonia.

Detection Frequency Optimization and Experimental Validation for Enhanced Knock Detection Accuracy

Tomoya Niki･Tomokazu Onda･Ryo Adachi･Shouki Nakaya･Hironao Satou･Masayasu Nagado･Kouki Kishimoto･Hiroya Takai (SUBARU)

In the development of high-efficiency engines aimed at achieving carbon neutrality (CN), maximizing hardware performance is necessary; however, this increases the risk of abnormal combustion events such as knocking, and makes it more difficult to distinguish abnormal combustion from normal combustion.To achieve both reliability and performance, technologies capable of accurately detecting abnormal combustion are essential.This report presents detection frequency optimization and experimental validation for enhanced knock detection accuracy.

Effect of alicyclic hydrocarbons on knocking intensity

Yamato Maruyama･Michio Nakano (Nippon Institute of Technology)･Kuniyoshi Eto (YAMABIKO)

In a two-stroke gasoline engine, knocking intensity became higher by using fuels which contain cyclohexane. In this study, the relationship between molecular structure and knocking intensity was experimentally investigated. As a result, it was suggested that the existence of a methyl group and a double bond in molecules affects knocking intensity.

Effect of Cycle-to-Cycle Variation of Combustion on Knocking

Taisei Shimizu･Shota Okuyama･yu Otoshi･yuki Imagawa･Kazunari Kuwahara (Osaka Institute of Technology)

LW integral shows that at the autoignition timing of 15 degrees ATDC, ignition delay time is about 10 crank-angle degrees essentially, regardless of engine rotating speed. When a fast cycle increases in-cylinder pressure and temperature so that ignition delay time can shorten to 10 degrees, autoignition occurs essentially. An SI engine has been operated using several fuels with different RON's, and knocking has been set at different timings. The experimental data have suggested that knocking is controlled by fast cycles in the cycle-to-cycle variation of combustion.

Knock Suppression and Thermal Efficiency Improvement in a Gasoline Engine Using Fuel Reforming

Shota Tsuji (Hokkaido university, Graduate School of Engineering)･Gen Shibata･Hideyuki Ogawa (Hokkaido university, Research Faculty of Engineering)･Jun Gotou (Yamaha Motor)

Hydrogen and methane addition to spark-ignition engines has been shown to suppress knock, and this effect is further enhanced under boosted conditions. In this study, the knock suppression effect of hydrogen and methane was quantitatively evaluated through engine experiments and examined using a detailed chemical reaction model. Furthermore, the combined effect of fuel reforming and boosting was investigated. The influence of reformed gas, generated at various exhaust gas temperatures, on thermal efficiency was analyzed. Based on these results, the effectiveness of fuel reforming and the optimal operating conditions for maximizing engine efficiency were discussed.

Proposal and Demonstration of a New Spark Ignition Combustion Method with a Gross Indicated Thermal Efficiency Exceeding 53% (First report)
-Concept of Improving Brake Thermal Efficiency-

Koji Morikawa･Takuya Nomura･Yasuo Moriyoshi･Tatsuya Kuboyama (Chiba University)･Atsushi Akamatsu･Yusuke Minami (Cosmo Oil Lubricants Co., Ltd.)･Tomohiro Nakayama･Ryo Muto (SUBARU)

Under the super-high boost conditions of a small pre-chamber gasoline engine, we devised a combustion method in which the super-lean main chamber mixture, which has difficulty in flame propagation, is burned within the range reached by the jet from the pre-chamber, and the remaining mixture is sequentially self-ignited and burned out. We investigated the pre-chamber specifications and engine operating conditions using 3D simulation, and performed actual engine verification, achieving a gross indicated thermal efficiency of 53% or more.

Proposal and Demonstration of a New Spark Ignition Combustion Method with a Gross Indicated Thermal Efficiency Exceeding 53% (Second report)
-Optimization of Combustion using 3D-CFD and Verification on Actual Equipment-

Takuya Nomura･Koji Morikawa･Yasuo Moriyoshi･Tatsuya Kuboyama (Chiba University)･Atsushi Akamatsu･Yusuke Minami (Cosmo Oil Lubricants Co., Ltd.)･Tomohiro Nakayama･Ryo Muto (SUBARU)

In order to establish the combustion method in the first report, the pre-chamber specifications were optimized using 3D-CFD, and it was confirmed that it could be realized at a high load of 2 MPa or more and λ = 3, and that a gross indicated thermal efficiency of 50% or more was possible. Furthermore, a single-cylinder combustion experiment achieved a gross thermal efficiency of 53% or more. It was found that this combustion method can greatly reduce cooling loss and unburned loss.

Intake Characteristics of Multi-Cylinder Gasoline Engines for Small Competition Vehicles
-Fundamental study of the effect of intake geometry-

Takumu Takayama･Shinobu Kasamatsu･Ikkei Kobayashi･Wenbao Wu･Jumpei Kuroda (Tokai University Graduate School)･Kazuki Ogawa (Aichi University of Technology)･Hideaki Kato･Takayoshi Narita (Tokai University)

The authors have been conducting ongoing research on improving the performance of multi-cylinder gasoline engines that can be installed in small competition vehicles. In this report, the authors focused on the shape of the surge tank portion of the intake geometry from the intake to the cylinders with air restrictors, and conducted a basic study on the effect of changing the geometry on the intake characteristics using CFD analysis.

Simulation of a scavenging process for a small 2-stroke gasoline engine

Koichi Hatamura (Hatamura Engine Research Office)･Tadahhige Kawakami (Hosei University)･Kuniyoshi Eto (YAMABIKO)･Akira Iijima (Nihon University)･Keiya Nishida (Hiroshima University)

Performance simulation of 2-stroke gasoline engines is often performed using 3D-CFD, but parameter studies are difficult due to long computation time. Here, we adopted a simulation method that combines 1D-CFD and 3D-CFD, and measured the pressure and other data of each part in actual operation for experimental verification.

Using the Integration of Manufacturing Process Simulations to Improve the Accuracy of Predicting Thermal Distortion in Outer Panels during the Painting and Drying Process

Kenjirou Baba･Kazuki Shouyama (TOYOTA AUTO BODY)･Shinichi Takezoe･Ryuichi Kaminishi･Katsushi Tsunoura (TOYOTA AUTO BODY R&D)･Takeshi Chino･Masahi Arai (JSOL)･Hirotaka Fukui･Takashi Fujiwara (TOYOTA AUTO BODY)

In order to achieve vehicle body lightweighting, the adoption of thin sheets for outer panels is desirable. However, it presents multiple manufacturing challenges. Among these challenges, predicting thermal distortion in outer panels during the painting and drying processes is particularly difficult. In this paper, we will introduce our efforts to improve prediction accuracy in this field by integrating several process simulations.

Development of press feasibility evaluation method using surrogate model

Takayuki Yoshimatsu･Shigeki Kojima･Takashi Kanai･Takaaki Harada･Koji Okamura･Daisaku Yanaga･Yuji Miyazawa･Mamoru Wakasa･Kiyoshi Nonomura (Toyota Motor)

Recent advancements in automotive styling design have made it more difficult to ensure the press formability of sheet metal and shorten development time using the conventional finite element method (FEM). Machine learning is considered an effective method for front-loading studies to ensure formability at an early stage. In this study, we propose methods to expand the training dataset for surrogate models and modify the target model for prediction. We also present the results of verifying the accuracy of surrogate model predictions.

Development of an Automated optimization Method for Resin Molding by Integrating CAE and Machine Learning

Yuto Takehara･Takayuki Nukui･Ryo Kamogawa･Yoshiko Hayashi･Kenji Takamura (AsahiKasei)

We developed an automated system that integrates CAE and machine learning to explore multi-objective optimization. By setting the exploration range, the system repeatedly executes CAE, builds surrogate models, and searches for optimal conditions. This presentation provides an overview of the algorithm and a practical example focusing on the molding analysis of resin products.

Development of a System for Efficient Confirmation Tasks to Prevent Return with Contents Using Object Detection (Report No.1)

Masahiro Kagi･Toru Hirai･Yuya Sakakibara･Riyo Kobe･Haruki Sei･Yuto Mori (Toyota Motor)

In the logistics process, all stacked boxes are visually inspected to prevent returns with contents; however, there is a problem with the long time required for this task. To address this, we developed a system that combines technology for automatically counting the number of boxes in images using machine learning with a weight scale, aiming to reduce the time required for the confirmation process.

Automated Technology for Determining the Quality of Cylinder Block Cavity through digital transformation

Hiroyuki Kimoto･Yuki Okahara･Tooru Iwaki･Hirotaka Sakamoto･Kunihiro Nobuhara (Toyota Motor)

To prevent oil leaks, skilled workers visually check the condition of Cavities, which is one of the causes of oil leaks. However, the lack of standards, which is based on intuition and tips, makes it difficult to transfer skills to other workers, which is an issue in the factory. To solve this problem, we have developed an automatic judgment technology that does not rely on humans, through digital transformation.

Electroplating Technology Using Solid Electrolyte Membranes for the Realization of Environmentally Harmonized Surface Treatment Processes

Masaaki Nishiyama･Akira Kato (Toyota Motor)･Hitoshi Inoue･Katsuya Houkibara･Hiroki Sato (Mikado Technos)

We have developed a new electroplating process called "Solid Electro-Deposition method" that significantly reduces CO2 emissions and waste liquid, thereby lowering environmental impact. This method features metal ion transport via a cation exchange membrane, achieving high deposition rates and uniform film thickness. With a dedicated hard mask, it enables direct formation of fine wiring, which is expected to reduce production costs. In this presentation, we report the details of the process principles.

Cleaning Technology of Plating Using Ultrasonic Mist for the Realization of Environmentally Harmonized Surface Treatment Processes

Kosei Goto･Takahiro Hiramatsu (TMEIC)･Masaaki Nishiyama･Akira Kato (Toyota Motor)

In recent years, the plating process has required reductions in the high environmental impact caused by the massive use of water and cleaning agents in the plating process and its preceding and following processes, as well as the effluent treatment. In response to this issue, we have developed a new cleaning process using fine mist generated by ultrasonic vibration. We report on the experimental results of the mist cleaning processes for rinsing, degreasing, and acid cleaning, and so on.

Development of mass production process for cold spray valve seat
-Application to the third generation e-POWER engine-

HIROHISA SHIBAYAMA･HIDENOBU MATSUYAMA･DAIKI HIROBE･TAKASHI IZAWA･HIRONAO NETSU･SHOTARO TAKAHASHI･JUNICHI ARAI･HAYATO HIRAYAMA･YOSHINORI IZAWA (Nissan Motor)

Nissan Motor Co., Ltd. had been working on laser cladded valve seat, but many issues such as cracks and porosity caused by cast raw materials made mass production difficult. However, by adopting the cold spray, solid-state bonding process, these issues were able to resolve. Additionally, the mass production system that can be added to the Cylinder Head machining line was developed and applied to the third-generation e-POWER engine.

A basic study on energy-efficient electric vehicle oils by applying oil film forming lubricant additive (2nd report)

Toshitaka Nakamura･Shinji Hasegawa･Takashi Furuse･Shinya Akahori･Kimikazu Itou･Soichiro Sakurada･Junnosuke Akiguchi (ENEOS)

The authors had previously developed a new additive that enabled low friction in drive units. In this study, the authors aimed to achieve further energy efficiency by utilizing the additive to suppress the increase in sliding loss through viscosity reduction. As a result of our investigations, we succeeded in developing an ultra-low viscosity EV oil that has significantly lower viscosity than commercial oils, combining energy efficiency with durability.

Study on low viscosity lubricants for electrified transmissions and compatibility with organic materials

Tsuneo Adachi･Yoshinori Ono･Walter Bunting (Afton Chemical Japan)･Christopher Cleveland (Afton Chemical)･Ryouta Iwasawa･Yumi Suzuki･Hitoshi Nakamura･Hiroyuki Kitajima･Hisashi Aoki (SUBARU)

In recent years, with the spread of electric vehicles such as HEVs and BEVs, it is expected that future lubricants and additive formulation designs for electrified vehicles will become more suitable for these applications. In this study, the effect of low viscosity lubricants on organic materials was investigated and the optimal lubricant formulation methods are explained.

Development of Fuel-Efficient Engine Oil Using Plant-Derived Materials Compliant with ILSAC GF-7 and JASO GLV-2

Yasunori Kanno･Rikuto Saito･Kazuma Yagura･Noriyuki Matui･Ko Onodera (ENEOS Corporation)

To achieve Carbon Neutrality (CN), reducing CO2 emissions through CN raw materials and improved fuel efficiency is crucial. By using plant-derived base oil to achieve CN and improving additives to comply with the latest engine oil quality standards (ILSAC GF-7, JASO GLV-2), it is expected to contribute to CN through the development of fuel-efficient engine oil.

Detection Method for Gear Pitting Using a Rule-Based Approach

Junnosuke Akiguchi (ENEOS)

In recent years, the viscosity of drivetrain lubricants has been decreasing, increasing the importance of pitting evaluation.
Traditional pitting evaluation relied on visual inspection for stage assessment, making it difficult to capture differences in lubricant performance.
However, by establishing a gear pitting detection method that combines vibration and rule-based techniques, it has become possible to more clearly compare differences in lubricant performance.

Considering the Issues of Achieving Carbon Neutrality in the Automotive Sector
-Focusing on Heavy-Duty Vehicles-

Shuichi Kanari･Hiroshi Hirai･Yuka Sato･Tetsuya Suzuki･Akiyoshi Ito (JARI)

The authors have developed CAMPATH, a quantification method for long-term CO2 emissions and co-benefit effects targeting the automotive sector. This paper aims to examine the challenges in achieving carbon neutrality, focusing on heavy-duty trucks and buses, using the scenario analysis results.

Research on Customer Acceptance of CO2 Extraction Behavior in Vehicles with CO2 Capture Technology

Kenji Uchida･Masahiro Horikoshi･Akiko Miura･Chikara Tanaka･Yuji Harada (Mazda)

In vehicles with CO2 capture technology, customers may need to extract CO2 from the vehicle. This study evaluates customer acceptance of such vehicles by quantifying the effort required for the extraction process and the measures to reduce this effort, using a survey and monetizing the results.

Applicability of moisture swing adsorption for CO₂ capture from engine exhaust

Yusuke Osawa･Ibuki Matsubara･Satoshi Sakaida･Kotaro Tanaka (Ibaraki University)

To capture CO₂ from exhaust gas of automobile, CO2 adsorption at high temperatures is desirable. Therefore, this study focuses on the moisture swing adsorption, which enables CO₂ adsorption and desorption by controlling the water content of the adsorbent, without the need for heat during desorption. The applicability of this method under high-temperature conditions was investigated.

Project to Develop and Promote Next-Generation Heavy-Duty Vehicles through Industry-Academia-Government Collaboration toward Carbon Neutrality

Tomoki Takashima (Logistics and Road Transport Bureau)

Regarding trucks and buses, which account for approximately 40% of CO2 emissions from the transport sector, the Ministry of Land, Infrastructure, Transport and Tourism, through collaboration between industry, academia and government, is working to achieve "Carbon Neutrality in 2050" by strengthening the promotion of 1) electrification technology for large vehicles and 2) development of internal combustion engines that use carbon-neutral fuels, including hydrogen and synthetic fuels.

LCA for electric vehicles in traveling stage in line with Paris Agreement

Keiichiro Sano･Yuuri Ujike (Kanto Gakuin University)･Yasuhiro Oi (Former Kanto Gakuin University)･Hiroshi Yagita (Nippon Institute of Technology)･Junichi Kasai･Katsuhiko Takeda (Kanto Gakuin University)

Each country has different energy sources and CO2 emissions during power generation. Based on the Paris Agreement, each country plans to achieve zero emissions, and it can be predicted that the environmental impact of power generation will decrease. In this study, the reduction in the CO2 emission intensity of power generation in the seven major automobile producing countries was predicted until around 2050. The reduction in the environmental impact of electric vehicles during their lifetime traveling was also predicted by LCA in each country.

Study of OSC materials from the viewpoint of catalyst deterioration on-board diagnosis

Akhmad Fadel Fadilla･Masami Nakamoto･Dai Sawada･Tetsuro Onishi･Kazuya Yasuda (DAIHATSU MOTOR)･Yuki Kazama･Shunsuke Oishi･Takashi Goto (CATALER)･Daiju Matsumura (Kwansei Gakuin University, Japan Atomic Energy Agency)･Hirohisa Tanaka (Kwansei Gakuin University)

Catalyst degradation is diagnosed by monitoring the OSC (Oxygen Storage Capacity) of the catalyst.
In order to correctly diagnose catalyst deterioration, which is required to be more accurate due to stricter regulations, we studied the improvement of the OSC expression rate in relation to the amount of Ce input.
By lowering the CZ ratio of the OSC material, the valence change of Ce became faster, and the OSC expression rate improved.
We also confirmed an improvement in the purification rate.

High Performance DPF to Tackle Nano Particulate Emissions for Off-Highway Applications

Shotaro Kato･Hiroaki Suzuki･Ryuji Kai･Takashi Aoki (NGK Insulators)

Diesel Particulate Filters (DPFs) have been widely used for PM/PN reduction in diesel applications. With the upcoming Tier 5 and EU Stage VI regulations, including stricter PM/PN limits and potential CO₂ targets, NGK developed DPFs using Cordierite (Cd) and Silicon Carbide (SiC) with various cell structures. Engine testing was conducted to evaluate filtration efficiency and pressure drop across filters with different mean pore sizes. The results identified optimal DPF configurations that support a common aftertreatment system for future global emission compliance.

PN10 Emission Behavior in Diesel Engines

Hiroshi Anoda･Haruki Goto･Genshirou Shibuya (Isuzu Motors)･Igor Gershkovich･Mojtaba Keshavarz (Isuzu motors germany)

In the next European Emission Regulation Euro7, the PN (Particulate Number) regulation will be strengthened, and the target particle size will be expanded from 23 nm or more to 10 nm or more. It is important to understand the PN10 emission behavior. This paper reports the results of investigation of PN10 emission behavior in a diesel engine.

Improvement of performance of catalyst-coated gasoline particulate filter by controlling catalyst density

Tomoya Takizawa･Hiroyuki Kurita･Takashi Araki･Kohei Sakai･Hiroshi Murakami (Mazda)

This research aimed to improve the PN filtration efficiency of catalyst-coated gasoline particulate filter without worsening pressure loss. In this report, characterizing the relationship between the density of the catalyst coated on substrate and above perfoemance, we revealed design concept of catalyst-loaded gasoline particulate filter for higher PN filtration, lower pressure drop, and higher three-way purification perfoemance.

Study on Factors of Performance Degradation of Urea SCR System Installed in Heavy Duty Vehicles during the Use Process

Toshiro Yamamoto (NALTEC)

Data on the NOx reduction performance of urea SCR systems (copper-based catalyst) installed in vehicles that comply with the 2016 exhaust gas regulations was collected continuously by conducting chassis dynamometer tests etc. as the cumulative mileage increased. Based on this, the factors that affect the exhaust gas reduction performance of the urea SCR system during use were analyzed, and the actual performance degradation was grasped. During use, a decrease in the SCR catalyst gas temperature was confirmed, which coincided with a downward trend in the NOx purification rate and was therefore considered to be factors in the deterioration of performance.

Effect of Ambient Humidity on Nitrous Oxide Emissions from Light Duty Vehicles

Shoi Koshikawa･Hisakazu Suzuki (Automobile and Land Transport Technology)

Ambient conditions around a vehicle affect the emission characteristics from the vehicle. Nitrous oxide (N2O), which has a high global warming potential, has been reported to have emission characteristics under various temperature conditions, but humidity has not been focused on. In this report, the effect of ambient humidity on N2O emissions from a gasoline vehicle was investigated using a chassis dynamometer.

High Porosity Substrate for PHEV

Daiki Suzuki･Takashi Aoki･Tasuku Matsumoto･Yuji Sasaki･Kai Matsumoto (NGK Insulators)

For Tier 4 regulations in the US, the NMOG+NOx emission limits will become tighter. In particular, plug-in hybrid electric vehicles (PHEVs) may experience emission deterioration during the switch from EV mode to engine mode, making improvements to the aftertreatment system a key challenge. The high porosity substrate is expected to reduce emissions during cold starts, and this paper presents the evaluation results of such an approach.

Systematic Approach to Define Operational Design Domain from Individual Traffic Scene for Automated Driving Systems

Keisuke Shimono･Mitsuaki Hagino･Kimihiko Nakano (The University of Tokyo)

Explainable ODD to local government and citizens is required in the implementation phase of automated driving system (ADS). Each traffic scene is considered to design and development for ADS should be summarized systematically. Traffic scene includes several elements, therefore, those elements can be analyzed by graph approach to explain coverages of defined ODD to each traffic scene along the planned service route.

A Study on How Training Data Quality Affects the Performance of a VQA-based Model for Driving Scene Retrieval

Sota Nakanishi･Kento Ohtani･Kazuya Takeda (Graduate School of Informatics, Nagoya University)

In the field of autonomous driving, it has been pointed out that the quality of training data can adversely affect a model’s generalization performance and output stability.
This study focuses on a learning method that uses Visual Question Answering . We test this method using datasets that contain label bias and label inconsistency, and examine how stable the learning is and whether it avoids learning incorrect patterns.

Validation of autonomous vehicle management using remote assistance

Yasuhiro Akagi･Ryo Kanamori･Takayuki Morikawa (Nagoya University)

The remote assistance is a method which a human operator gives advice to an autonomous driving system to change its driving behavior from a remote location. In this paper, we impliment a remote assistance system to give advice for each traffic scenarios, such as passing through an unsignalized intersection, crossing a pedestrian crossing, and avoiding parked vehicles. We report on the effectiveness of the system based on field experiments in actual urban areas.

Occluded Vehicle Presence Estimation via Observable Vehicle Behaviors for Intersection Motion Planning

Koki Morita (Graduate School of Infomatics, Nagoya University)･Eijiro Takeuchi (TIER IV, inc.)･Kazuya Takeda (Graduate School of Infomatics, Nagoya University)

In autonomous driving, safe and efficient decision-making under occluded conditions is a critical important task.
overly conservative behavior that assumes the presence of unseen vehicles can cause unnecessary delays in traffic flow. We propose a method that observes the actions of visible surrounding vehicles and applies constraints to phantom vehicles in occluded regions, enabling more efficient motion planning. Using NuScenes dataset, real-world driving data, we demonstrate that our risk-constraint approach achieves more efficient decision-making than conventional models based on worst-case assumptions.

Development of Other Vehicle Behavior Model for BEV Thermal and Dynamic Evaluation Simulator

Masahiro Nojima･Masaki Morita･Takuji Horimoto (Toyota Motor Co.)

In BEV development, many new thermal induced power development issues have emerged. So, evaluation is necessary, but currently there were problems with man-hours and other constraints for on-site evaluation, making it desirable to utilize a driving simulator. However, it was not possible as traffic flow had not been established.
In this study, we developed an algorithm to extract big data from other vehicles, taking into account the traffic dynamics and interactions with our own vehicle. This algorithm accurately reproduces real-world conditions, enabling implementation and evaluation in a driving simulator.

Study on development efficiency and system cost reduction through BEV charging service platform

Midori Sugiyama･Yoshihiro Sakayanagi･Masato Ehara･Takahiro Hirano･Tsubasa Otohata (Toyota Motor)

To achieve carbon neutrality by 2050, we are developing a management system that integrates energy management with mobility services. The purpose of this work is to develop a platform that enhances development efficiency, shortens lead times, and reduces operational costs through using of APIs, communication protocols, and serverless architecture. Additionally, we summarize effects and insights gained from demonstration experiments.

Development of Logistic Demand Estimation Process and Supplementary Methods for Predicting Future Changes in Truck Demand.

Kenta Shintoku (Kozo Keikaku Engineering)･Nobumasa Ohashi･Junichiro Nitta (ISUZU ADVANCED ENGINEERING CENTER, LTD)･Ryoko Maeda (Kozo Keikaku Engineering)

In this study, we develop a future demand forecasting process for trucks based on public statistical data such as the Logistic Census. To address data limitations, we incorporate supplementary estimation methods based on prior research, allowing evaluation demand by regions, transportation modes and categories. Furthermore, through scenario analyses that takes into account the expected progress of modal shift, we provide a framework to capturing future structural changes in logistic demand. This study demonstrates the effectiveness of combining structured forecasts with data-based supplementation to support strategic planning regarding future trends in logistic demand.

Design and Evaluation of a Virtual Traffic Light (VTL) Control Algorithm Adaptive to Traffic Demand

Keita Sakai (Toyo University Graduate School)･Hironori Suzuki (Toyo University)

By using vehicle-to-vehicle (V2V) communication technology, Virtual Traffic Lights (VTL) can control intersection traffic flows more efficiently than conventional physical traffic lights. In this study, we design a novel VTL control algorithm that can flexibly respond to fluctuations in traffic demand. The proposed algorithm is implemented in a traffic flow simulator, and its effectiveness in improving traffic performance is evaluated through multiple scenarios.

Trajectory Prediction of Traffic Participants in Interaction Scenes at Signalized Intersections

Quy Hung Nguyen Van･Heishiro Toyoda (Toyota Motor)･Cui Xiongyi･Rosman Guy (Toyota Research Institute)･Kimimasa Tamura (Woven by Toyota)

In this paper, we present our approach to predicting the trajectories of traffic participants at signalized intersections in urban areas in Japan. Based on measurement data from sensors (cameras, lidar) installed at intersections, we focus on interactions between traffic participants (particularly, crossing pedestrians, bicycles, and vehicles turning right and left), and investigate the feasibility of learning and predicting trajectories in situations where real interactions between traffic participants occur by utilizing advanced deep learning models.

A Robust License Plate Recognition System Against Environmental Changes Using Vision-Language Models

Kota Shinjo･Shintaro Yoshizawa･Yuto Mori (Toyota Motor)

License plate recognition systems have been used for parking lot management and traffic monitoring, but it is desired to expand the scope of their use to wider fields, such as factory premises and smart cities. To this end, we have developed a technology to realize more advanced license plate recognition with high accuracy by utilizing a visual language model that can flexibly respond to a variety of images.

Study on Yield Strength Prediction after Bake Hardening of 6000 Series Aluminum Alloys Using Machine Learning

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

The 6000 series aluminum alloys used in automobile panels undergo hardening namely Bake Hardening (BH) after forming strain and/or paint baking. Combinations of such conditions affect the yield strengths; therefore, identifying the relationship of those combinations and yield strengths requires a large number of tension tests. This study aims to establish a prediction method for the yield strength after BH under arbitrary combinations of conditions without significantly increasing the number of tensile test data volume by applying machine learning.

Strength Properties of Steel/Aluminum Dissimilar Spot Welded Joint (First Report)
-Investigation of Tensile Shear and Peel Strength-

Ayaka Kagami･Eisuke Umeno･Naoki Horita･Tetsuya Fujisaki (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 tensile shear strength and L-shaped peel strength and present the relationship with the nugget diameter.

Development of heat-radiative aluminum coating material for automotive component housings

Hironori Watanabe･Osamu Katou･Yoshihiko Kyo (UACJ Corporation)

The heat-radiative aluminum coating material can be used as housings for electronic devices and automotive components, and are thought to contribute to thermal control by increasing the heat radiation from the coating, which promotes heat radiation. In this report, we present the results of an investigation into the relationship between the contained particles and coating performance by adjusting the particle size and concentration of silica contained in epoxy resin-based paints.

Nitriding Behavior of Stainless Steel in Ammonia Combustion Atmosphere

Yoshitomo Fujimura･Atsutaka Hayashi･Naoki Hirakawa･Jun-ichi Hamada (Nipponsteel)

Assuming ammonia combustion, the nitriding behavior of stainless steels at 600℃ for 50 hours in NH3-H2O-N2 atmospheres were investigated. The nitride layer formed on the surface of austenitic stainless steels is thinner than that of ferritic stainless steels. Even in ferritic stainless steel, nitriding tended to be restrained in a low NH3 atmosphere.

Bending fatigue behaviors of T-shaped Ni alloy brazed joints

Gyoko Oh･Atsushi Umezawa (Tokyo Roki)

Tests and numerical stress analyzes were conducted on the relationship between fatigue strength, fracture behavior, metallographic structure, and stress concentration of Ni alloy brazed joints of ferritic stainless steel. It was clarified that the surface layer of the brazing alloy was enriched with P and Cr, forming a solidified structure of Ni-Cr-Fe-Si-P, that the radius of curvature of the fillet had an effect on stress concentration, and that these factors were quantitatively related to fatigue limits.

Material Development for Cold Spray Valve Seat

Yoshinori Izawa･Junichi Arai･Hayato Hirayama･Shotaro Takahashi (Nissan Motor)

In order to form straight ports important for tumble flow reinforcement, materials for Cold Spray Valve Seat were developed. Cu-based material powder which satisfies contradictory requirements of ductility　necessary for coating and hardness necessary for wear resistance and Fe-based hard particle with the same lubricity as Co-base hard particle were designed. Finally, we achieved high wear resistance by combined coating layer.

Development of Steel for Carbo-Nitriding with Superior Pitting Fatigue/Bending Fatigue Strength

Arisa Ito･Tomoya Tamai･Ryosuke Ohashi･Ayumi Yamazaki (Daido Steel)

Gears for Reduction gear used in e-Axle, which are attracting attention as the drive unit for electric vehicles, require high strength in both tooth flank and tooth root properties. Carbo-nitriding process is a treatment that improves strength properties by increasing surface hardness and softening resistance. In this study, a steel with superior pitting fatigue strength and bending fatigue strength was developed by carbo-nitriding.

Development of frame with high performance using hot stamping

Yumi SAITO･Naoki KIMOTO (Nippon Steel)

As the growing popularity of electric vehicles, both cost reduction and safety enhancement of battery packs are desired. In this study, we focused on frames in battery packs. Using hot stamping materials enabled the achievement of high-strength frames with continuous flanges due to the high strength and high formability of materials. Consequently, an increase in stiffness and load capacity was indicated.

The Influence of Secondary Forming on Sheared Edge Delayed Fracture

Yuichi Matsuki･Junya Tobata･Toyohisa Shinmiya･hideyuki Kimura･Tsuyoshi Shiozaki (JFE Steel)

The application of ultra-high-strength steel sheets is expanding to achieve both lightweight automotive body structures and improved collision characteristics; however, delayed fracture at the shear edge remains a challenge. In this study, shear processing was performed on ultra-high-strength steel sheets, and secondary forming involving tension and compression was applied to the shear edges. Subsequently, delayed fracture tests were conducted under stress loading conditions to investigate and discuss the effects on delayed fracture characteristics.

Consideration on Vibration Durability Evaluation Using Simultaneous Three-Axis Excitation

Katsuhiko Nakamura･Tatsuki Okunaga (IMV)･Kenji Yoshida･Tsukasa Ohzawa (DENSO)･Tetsuya Hyakutake (SOKEN)

In actual operating environments, products are subjected to multi-degree-of-freedom vibrations. While design evaluations have conventionally been conducted using sequential single-axis excitation in three directions, the adoption of simultaneous three-axis excitation is gaining attention. In this study, using a simple test specimen, the evaluation results of the different excitation methods were quantified using vibration energy. The differences in these results and their underlying factors are clarified and discussed.

Improving the Fatigue Limit of Spot-Welded Tensile Shear Joints Using 980MPa-class High-tensile Steel Plate as the Base Material
-Improving the Fatigue Limit due to a Single Overload-

Kotaro Tanaka (Graduate School of Science and Technology, Nihon University)･Akifumi Okabe･Noboru Tomioka (Nihon University)

A spot-welded tensile-shear joint with a base material of 980MPa-class high-tensile steel plate was subjected to a constant amplitude load fatigue test after applying a single overload in advance to impart compressive residual stress to the crack initiation site and its surroundings, and it was confirmed that the fatigue limit was improved by the single overload. It was also shown that the fatigue life with and without a single overload can be uniformly evaluated by using the effective strain range.

Fatigue Strength Evaluation of Spot Welded Joints Using Infrared Thermoelastic Method

Hideki Ueda･Hiroshi Shiromizu (Nippon Steel)･Reiji Tanaka (Nippon Steel Technology)

We investigated the effect of load frequency using thermoelastic finite element (FE) analysis on spot welded joint commonly used in automobile parts. To simulate the thermoelastic effect, we developed a stress field-temperature field thermoelastic FE analysis technique that calculates the heat transfer of heat generation and heat absorption according to compression and tensile stress. The calculated stress distribution showed a good agreement with thermoelastic stress distribution measured using an infrared ray method. Moreover, we verified the accuracy of estimating the fatigue limit obtained from the point of sudden increase in dissipated energy by infrared measurement.

Development of Analytical and Evaluation Techniques for Enhancing the Performance of Integrated Hot Stamped Components　

Masahiro Kubo･Naoki Kimoto･Tohru Okada･Satoshi Shirakami (Nippon Steel)

The application of hot-stamped steel sheets in integrated automotive structural components, such as cabin frame structures, is increasingly prevalent. This report focuses on the development of analytical and evaluation techniques aimed at enhancing the performance of these components, with a particular emphasis on the analysis and evaluation of overlapping sections.

Development of Energy Transmissibility Model for Three-Degree-of-Freedom Vehicle Dynamics

Atsushi Kosegawa (Graduate School of Kanagawa University)･Toru Yamazaki･Kai Kurihara･Kazurou Iwata (Kanagawa University)

This study proposes a novel approach that applies energy transmissibility models to conventional vehicle dynamics models used for evaluating steering characteristics, steering response, and straight-line stability, in order to describe these phenomena from an energy-based perspective. Furthermore, the effects of changes in vehicle mass on steering response under various steering characteristics are described using the energy transmissibility model.

Dynamic Evaluation of Straight-Line Stability and Steering Components Based on an Energy Transmissibility Model

Toru Yamazaki (Kanagawa University)･Atsushi Kosegawa (Graduate School of Kanagawa University)･Kai Kurihara･Kazuro Iwata (Kanagawa University)

The energy transmissibility models of planar motion and roll motion are applied to a vehicle dynamics model to evaluate the influence of roll disturbances on straight-line stability from an energy-based perspective. In addition, by incorporating a model that accounts for the effects of hub bearings, which significantly influence the vehicle's steering response, the system is analyzed from an energy viewpoint to derive new design guidelines.

Coordinated Control of Driving/Breaking and Steering for Vehicle Stability Improvement on Split-μ Roads.

Hiroki Kamiya･Akira Ito (Aichi Institute of Technology)

This study proposes an MPC-based control method to improve vehicle stability on split-μ roads by coordinating driving/braking forces and independently controlled steering. The control utilizes road surface friction information predicted in advance by external sensors to achieve cooperative control.

Study of the Torsion Bar Stiffness Design of Electric Power Steering System

Takashi Miyoshi (Honda Motor)

In this study, we investigated the characteristics of a closed loop that combines an EPS system with a two-wheel model in order to express the sensory evaluation of the effect of enhancing the torsion bar stiffness of the EPS system. In this characteristic calculation, we obtained a design guideline for the torsional stiffness of the torsion bar of the torque sensor.　Furthermore, the suggested system was installed into a vehicle and its effectiveness is confirmed.

Study on handling assist control based on rear wheel sideslip angle

Naoto Ohkubo･Ryo Koyama･Fumiaki Honjo (Honda Moter)

In order to make it easier for the driver to trace the desired driving line even on slippery road surfaces, rear wheel sideslip angle feedback control that applies restoring yaw moment based on the rear wheel sideslip angle obtained from the estimator has been devised. The control effectiveness was confirmed through simulation and actual vehicle tests.

Study on roll behavior and improvement of dynamic cornering characteristics with front-rear relative roll angular velocity compensation control

Toshiki Matsumoto (Advanced Technology Development Division Integrated Application Development Dept.)･Yosuke Yamada (Product Validation Dept.)

Focusing on the fact that the relative transient behavior of the front and rear roll motion of the vehicle body, which is caused by the rigidity of the vehicle body, affects the “feel of connectedness" at the initial steering and the "predictability" during cornering, etc., we verified the effect of improving roll behavior and maneuverability characteristics during cornering with front-rear relative roll angular velocity compensation control using a variable damping force suspension (AVS).

Application of Data-Based Preview Controller to Torsion Bar Active Suspension

Hiroki Furuta･Jin Hozumi･Takashi Saito･Tatsuya Keida (Toyota Motor)

Torsion bar active suspension with using electronic motor is environmentally friendly and has advantage in cost because it is oil-less and possible to share parts with other chassis components. However, it has disadvantage in response, therefore in this paper, data-based preview controller proposed by us is applied to the torsion bar active suspension to improve control effectiveness.

Study on Self-optimizing Traction Control by Estimating Road Friction and Application to Autonomous Lawnmower

Kyohei Sakagami･Akiko Ito (Honda R&D)･Takayuki Arakawa･Yuichi Kawasaki (Honda Motor)

Autonomous lawnmowers require more accurate tracking than passenger cars, because even the slightest path error can result in grass being left uncut. Sudden changes in traction force can damage the grass, therefore, this problem cannot be solved by simply improving sensor accuracy or increasing control gain. In this paper, we propose a method to estimate road frictional coefficient based on the vehicle and traction force model and optimize the traction force of the left and right wheels.

Analysis of Handling Stability under Combined Steering and Road Irregularity Inputs

Ayumu Tanaka･Yasuji Shibahata･Makoto Yamakado･Masaki Yamamoto･Masato Abe･Yoshio Kano (Kanagawa Institute of Technology)

Most analyses of handling stability have been carried out on flat roads without road surface irregularities, and ride comfort analyses have been carried out on straight-line driving without steering input.
In this study, analyses of handling stability under combined steering and road surface irregularity inputs . In this report, a five-degree-of-freedom motion model is constructed considering road surface irregularities, and the effects of vertical friction of the suspension are investigated.

Analysis of the Impact of Changes in Vehicle Dynamics on Driver Operation.

Yoshinori Maeda (Toyota Motor)

This study examines the effects of changes in vehicle dynamics on driver perception and operation using a driving simulator. The results show that favorable vehicle dynamics are linked to a decrease in the peak value of steering speed. Analysis using τL reveals an increasing trend in τL, indicating that higher τL values lead to smoother driving operations, potentially resembling the behavior of experienced drivers.

Evaluation of Steering Characteristics Using τL and Steering Robot Tests on a Brake G-Vectoring Controlled Vehicle

Ibuki GENPEI･Makoto YAKAKADO･Masato ABE･Yoshio KANO･Masaki YAMAMOTO (Kanagawa Institute of Technology)･Tomohisa SHIBATA (Toyota Motor)

To explore applications in emergency avoidance, this study investigates the improvement of transient handling stability during steering using high-gain brake-based G-Vectoring Control. Open-loop transient characteristics were assessed via steering robot tests on a real vehicle. Driver margin was quantitatively evaluated using τL identification through lane-change experiments conducted with multiple drivers, confirming consistency with subjective steering characteristics.

Study on construction of system for estimating friction characteristics between tire and road on the forward road surface
-Sensor selection and algorithm construction for forward road friction characteristics estimation system-

Atsushi Watanabe･Ichiro Kageyama･Yukiyo Kuriyagawa･Tetsunori Haraguchi (Nihon University)･Tetsuya Kaneko (Osaka Sangyo University)･Minoru Nishio (Absolute Co., Ltd.)

In the previous report, we reported on road surface categorization utilizing multiple environmental information related to road surface friction characteristics on snowy and icy roads. In this study, we investigated the selection of effective sensors and the construction of an estimation algorithm for estimating the friction characteristics of the forward road surface. As a result, the effectiveness of the proposed method is verified and the feasibility of a forward road surface friction estimation system is discussed.

Vibration Analysis of Tire Using Compressed Sensing DIC

Yuki Kato (Kochi University of Technology)･Soma Watahiki (Kozo Keikaku Engineering)･Masayoshi Otaka (Ono Sokki)･Mitsuki Togoshi (Kozo Keikaku Engineering)･Yoshiho Oda (Ono Sokki)

Running tires exhibit complex vibration behavior due to excitation forces from the road surface and engine. However, it is difficult to measure vibration using a contact sensor with a cable because the tire is a high-speed rotating body. In this study, we developed a method to measure detailed vibration shapes and spectra of tires using compressive sensing and digital image correlation.

Experimental Analysis Method of Sprung Vibration Characteristics for Suspension Inputs
-Vehicle Electrification Impact Analysis Including Longitudinal and Lateral Inputs-

Tsuyoshi Yoshimi･Shingo Koumura (Toyota Motor)

For efficient development of ride comfort performance, it is useful to have analysis technology that separates the input from unsprung to sprung and the sprung response characteristics caused by elastic deformation of the body, etc. In this paper, we have developed a method to measure the sprung response characteristics not only for vertical inputs, but also for longitudinal and lateral inputs, and verified the usefulness of this method by considering the changes in response characteristics due to electrification of vehicle.

Vibration sensation evaluation based on a reproduction of vehicle vibration using a vibration exciter

Sota Tanaka･Gen Tamaoaki (Tokyo Metropolitan University)･Shuya Nojima･Hirotaka Shiozaki (Mitsubishi Motors)･Takuya Yoshimura (Tokyo Metropolitan University)

We investigate which directional components of vehicle vibration contribute to ride comfort by evaluating them through vibration experiments that simulate vehicle vibrations using a 6-axis exciter. Subjects seated on an automobile seat are excited by the following vibrations and evaluate their ride comfort. The base vibration is the vehicle vibration measured while the automobile traveled on a rough road. Adjusted vibrations are vibrations created by increasing or decreasing one directional component of the base vibration. Corrected vibrations are vibrations modified by other directional components to compensate for the loss of vibration power caused by a decrease in the directional component.

NV prediction technology for excitation force and vibration transfer using Multi-Body Dynamics CAE in the development of electric drive unit

Toshio Kageyama (AVL JAPAN K.K.)

Effective measures for noise vibration are to reduce the excitation force and vibration transfer. In general, it's not easy to distinguish whether the root cause is the excitation force or the vibration transfer when an abnormal noise occurs in the final stage of prototyping. We use a multibody dynamics analysis model that simulates actual operating conditions, and this presentation will introduce these efforts.

Construction of numerical model for in-vehicle sound field based on the exploration of phase difference during reflection

Takayuki Masumoto･Masahiro Takekawa (CYBERNET SYSTEMS)･Kazushi Kuroyanagi･Akira Shigeta･Hiroyuki Kumakura (JVCKENWOOD)

An attempt was made to build a numerical model that reproduces measured SPL values at multiple points in a vehicle. In this report, surface impedances, which are variables in the model, were organized based on sound absorption coefficient and reflection phase difference and were assigned to wall groups roughly generated based on the components. Appropriate values those could reproduce measured SPLs were explored through parameter studies in which these values were varied. The sensitivity of the sound absorbent material and microphone position to the response was also confirmed.

Proposal of a New Unit Mode Extraction Method

Takafumi Mochizuki･Hiroyuki Suzuki･Takao Hirai･Kazuki Hidaka･Moe Hanashima (Estech)

We propose the idea that vibration characteristics can be decomposed into modes with simple shapes called “unit modes”. Analyzing with these modes make the vibration mechanism very clear. We have previously reported that it is possible to easily study response reduction by changing the resonant frequency of unit mode. This research introduces a new method that solves the problems encountered with conventional extraction methods.

The Influence of Mass and Stiffness Distribution on the Vibration Characteristics of Automobile Bodies

Ryo Ageba･Kazuhiko Higai･Tsuyoshi Shiozaki (JFE steel)

Approaches to improve the vibration damping of automobile bodies include measures to reduce vibrations from the source to evaluation points, as well as controlling the body’s natural frequencies. An example of the latter, focusing on the optimization of mass distribution, was reported in 2024. This report evaluates the impact of changes in stiffness at various locations, such as through bead application, on the overall vibration characteristics of the vehicle body.

Evaluation of Vibration Characteristics of Bolted Joints Using Aluminum Alloy Bolts and Titanium Alloy Bolts

Yuuki Kawaharabashi･Satoru Kuga･Yoshinao Kishimoto･Yukiyoshi Kobayashi･Tristan Samuel Britton (Fujimori)･Keisuke Inoue (Tokyo City University)

Bolted joints are relatively easy to assemble and disassemble, but the use of many steel bolts and nuts leads to an increase in the total weight of the car body. In this study, the effects of replacing steel bolts and nuts with aluminum alloy and titanium alloy bolts and nuts, which are lighter than steel bolts and nuts, on the vibration characteristics of bolted joints were evaluated by hammering tests and the finite element analysis.

Vibration Characteristics of Bolted Joints in Magnesium Alloy Based Multi-Material Structures

Tristan Samuel Britton (Fujimori)･Keisuke Inoue･Yoshinao Kishimoto･Yukiyoshi Kobayashi･Yuuki Kawaharabashi･Satoru Kuga (Tokyo City University)

Magnesium alloy is the lightest structural metal, and it is known for its high damping performance. Therefore, it is expected to be applied on next-generational body structures. This study has investigated the vibration characteristics of bolted joints in magnesium alloy based multi-material structures by hammering tests and finite element analyses in order to establish an analyzing method that is applicable for the vibration characteristics prediction.

A technique for estimating air-borne noise propagation characteristics from the battery unit to the vehicle interior to consider high-frequency ripple noise

Kenya Fujii (Honda Motor)･Hitoshi Taira (AUTO TECHNIC JAPAN)･Naoki Toyama (Honda Motor)

We developed CAE technology to predict the air propagation characteristics of high-frequency ripple noise generated by the high-voltage battery unit of an electric vehicle. The development method used FEM and coupled analysis of the exterior acoustics, structure, and interior acoustics models. By appropriately considering the Biot parameters of the carpet and the interior sound absorption coefficient, we obtained CAE results that showed good agreement with actual measurements in the high-frequency.

NVH Development Process and Modeling Techniques for Electric Vehicles Using a Driving Simulator

Kenji Torii･Shion Mise･Fujii Kenya (Honda Motor)･Sellerbeck Philip･Philippen Bernd (HEAD acoustics)･Kenta Tanabe (HEAD acoustics Japan)

In the development of electric vehicles, there is a strong demand for enhanced development efficiency through shorter development cycles and reduced costs and labor. To address this need, the authors have established a development process that utilizes a driving simulator to evaluate NVH performance from the early design before the production of prototype vehicles. This presentation introduces an overview of the proposed development process and the modeling techniques that support it.

Development of a Machine Learning Model to Predict Engine Noise Perception Based on Cabin Noise and Vehicle Parameters

Shinichi Suganuma (Chuo University, Graduate School of Science and Engineering)･Shimpei Nagae (Nissan Motor)･Takeshi Toi (Chuo University)

Interior cabin noise and vehicle parameters were recorded simultaneously during on-road driving while drivers rated engine-noise annoyance on a three-level scale. A machine-learning model using only cabin noise as input achieved 56% accuracy in predicting these ratings. Adding engine speed, driveshaft torque, and vehicle speed increased accuracy to 65%. These findings demonstrate that vehicle parameters, in addition to cabin noise inputs, significantly influence perceived engine-noise annoyance.

Development of a Machine Learning Model to Predict Engine Noise Perception Considering Temporal Driving Conditions

Shinichi Suganuma (Chuo University, Graduate School of Science and Engineering)･Shimpei Nagae (Nissan Motor)･Takeshi Toi (Chuo University)

Engine speed, driveshaft torque, and vehicle speed—the driving parameters most strongly associated with subjective engine-noise annoyance—were used as inputs to a machine-learning model that predicted three-level annoyance with 65 % accuracy. Adding a five-second history of engine speed preceding the subjective evaluation raised the accuracy to 73 %. These results quantitatively demonstrate that short-term temporal factors significantly influence perceived engine-noise annoyance during driving.

Development of automatic evaluation system for BSR (2nd Report)

Tatsuya Sakuishi･Kazutaka Yonemori･Takaaki Yamanaka･Yoshinari Tokunaga･Yohei Kurami (Nissan Motor)

At the 2024 Autumn Conference, we reported on the development of an automatic evaluation system for abnormal noises, specifically BSR (buzz, squeak, and rattle), caused by rattling and friction. To apply this system to vehicle development, we worked on automatic classification of noise occurrence locations and utilized past knowledge to propose causes and countermeasures. Additionally, we enhanced noise detection performance through advanced signal processing. The details of these developments were presented at the conference.

Study on Psychoacousic Indices for Evaluating Annoyance Caused by Fluctuating Wind Noise

Tomoya Washizu (Nissan Motor)･Toshihiko Komatsuzaki (Kanazawa University)･Takuya Yoshimura (Tokyo Metropolitan University)･Akiyoshi Iida (Toyohashi University of Technology)･Toru Yamazaki (Kanagawa University)･Yuichi Matsumura (Gifu University)･Takenori Miyamoto･Keiichiro Iida (Suzuki Motor)･Keiichi Taniguchi (Nissan Motor)

A large scale auditory evaluation test was conducted to investigate the characteristics of fluctuating wind noise, which is unpleasant for passengers during high-speed driving.
Psychoacoustic indices highly correlated with the annoyance got from the auditory evaluation test were studied using psychoacoustic evaluation quantities, including sharpness and roughness, as well as modulation spectrum analysis.

Analysis of Crossing Pedestrians' Decision at Unsignalized Crosswalk Using Logistic Regression

Shunto Araki･Takashi Nishimoto･Hiroyuki Okuda･Tatsuya Suzuki (Nagoya University)･Kazunori Ban (Toyota Technical Development)

Replicating diverse traffic scenes in traffic simulations plays an important role in validating ADAS/AD systems. In this research, pedestrian crossing decision-making at an unsignalized crosswalk is analyzed using the logistic regression analysis. Pedestrians' behavior is observed using our simulator, and the various individual characteristics of pedestrian crossing decisions are analyzed.

Near-miss verification using a driver-pedestrian model at an unsignalized intersection

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

Human movement is often said to be realized through cognition, judgment, and motion, and these errors result in near-misses and traffic accidents. The decision model for drivers and pedestrians can explicitly represent errors in cognition, decision, and motion. Therefore, this paper verify the extent to which near-miss events occur due to each of these errors.

Analysis and Modeling of Cyclists’ Intersection-Crossing Behavior Using a Neural Network Model

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

To evaluate autonomous driving systems of vehicles through simulation, it is necessary to model the behavior of traffic participants. In particular, bicycles are a critical safety factor due to the various movements caused by cyclists’ ambiguous understanding of the rules. This study analyzes and models cyclists’ decisions and behaviors toward left-turning vehicles at intersections using deep learning, based on data collected with a cycling simulator.

Evaluation of driving training for passenger comfort by the vestibular surprise model

Keita Teshima･Masatoshi Takayama･Tomoo Kosaka･Mitsuhiro Narusue･Sho Yabunaka･Daichi Sato･Takeshi Yabuki･Masayuki Watanabe (Mazda)

We reported previously that the vestibular surprise model could be used as a human model to evaluate vehicle behaivor. Here, we adopted the same model to examine whether it could also evaluate driving skills for passenger comfort. Drivers were trained by an expert instructor from the Mazda Driving Academy. We compared the vestibular surprise of passengers seated in the rear seat before and after the drivers' training. We found that the driving training reduced the vestibular surprise of passengers. We conclude that the vestibular surprise model could be used as a tool for evaluating driving skills for passenger comfort.

Proposal of a Steering Assist System Considering Individual Driver Input Constraints: Second Report
-Evaluation Results with Elderly and Physically Limited Drivers-

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

Proposed earlier mixing-input shared control steering assist system was evaluated with elderly drivers and drivers whose range of motion is limited by physical constraints. Using a VR driving simulator, we examined steering workload reduction and other effects, and report the results.

Analysis of Abdominal Visceral Dynamics during Whole-Body Vibration Using a Human Body Finite Element Model

Toru Hamasaki･Yuko Nakahira･Masami Iwamoto (Toyota Central R&D Labs.)

In this study, we investigated the abdominal visceral dynamics under whole-body vibration using a human body finite element model. The model incorporated muscle activity to maintain a seated posture and adopted an implicit solver to enhance the computational efficiency of long-duration simulations. The simulation results indicated that the abdominal viscera underwent compressive and tensile deformation owing to phase differences between the thoracic and external excitation displacements, with peak deformation observed at approximately 5 Hz. Such deformations may induce the neural activation of mechanoreceptors within the abdominal viscera, potentially contributing to abdominal discomfort in moving vehicles.

Development of a method to predict the behavior of Engine parts in the market by combining big data and machine learning

Yuki Otsuka･Kenta Yoshii･Kazuhiko Ymakami･Kazuaki Watanabe･Kohei Tanaka (Honda Motor)

Estimating how engine components behave in the market is important for the development of high-quality engines.
The authors developed a method to estimate the behavior of components in the market by applying machine learning to market data.
The validity of the estimation was verified by loading the estimated component behavior on a stand-alone test machine.

Experimental Study on the Seizure Process in a Rig Test Machine for Evaluating Engine Bearings

Motohiko Koushima･Mari Nagata･Tadamichi Tamura･Shinichi Sakurai (Daido Metal)

This study conducted seizure tests using a rig test machine for evaluating automotive engine sliding bearings. Detailed analysis of the seizure process was based on temperature and torque data obtained during tests. The study clarified how bearings in a hydrodynamic lubrication state lose their oil film and progress to seizure. The results will be presented in this report.

Analysis of Oil Supply to Piston Skirt

Tomoya Jinnouchi･Kenta Sato･Hisanobu Kawashima･Hidekazu Suzuki･Tsuneaki Ishima (Gunma University)

The oil film thickness on the piston skirt and cylinder wall were observed to understand the oil supply process in the engine. The oil film thickness and its pathways were evaluated. It was confirmed through visualization that oil is mainly supplied to the piston skirt from the lower edge of skirt during the piston’s downward stroke. Additionally, it was observed that oil was also supplied to the skirt from other regions besides the lower edge.

Research on Cylinder Thermal Insulation Films and Evaluation Analysis Techniques for Reducing Cooling Loss of Engines (1st Report)
-Design of Thermal Insulation Materials, Coating Methods, and Evaluation of Thermal Insulation Performance-

Kentaro Shinoda･Koichi Kinoshita･Shahien Yamada Mohammed･Abe Haruka･Megumi Akoshima･Eishi Kubota (AIST)･Takayuki Ito (JARI)

In order to improve the thermal efficiency of engines, it is important to reduce cooling loss, and the formation of heat-shielding films on the engine combustion chamber walls has attracted attention. In this study, we aim to establish material design, film formation, and evaluation methods to improve the performance of heat-shielding films by using a film formation technology using the hybrid aerosol deposition (HAD) method developed by AIST, and we will report on the progress of our research.

Research on Cylinder Thermal Insulation Films and Evaluation Analysis Techniques for Reducing Cooling Loss of Engines (2nd Report)
-Evaluation of Thermal Properties of Thermal barrier coating-

Haruka Abe･Kentaro Shinoda･Megumi Akoshima･Koichi Kinoshita･Shahien Yamada Mohammed･Eushi Kubota (AIST)

The HAD method, a film formation technology developed by AIST, is a solid-phase particle lamination method in which solid particles are sprayed and deposited without melting, and because low thermal conductivity is expected, it is expected to be used as a heat barrier film on engine combustion chamber walls, etc. In this study, we report on the evaluation of thermal conductivity properties by measuring thermal diffusivity, specific heat, and density using a sample formed on a metal substrate using ceramic fine particles by the HAD method.

Development of Thermal Barrier Coating Using Low Thermal Conductivity Material for Piston（2nd Report）

Ryoko Yamanoi･Kazuki Ogiwara･Teppei Tano･Shiori Yoda (ART metal manufacturing)

To improve the thermal efficiency of the engine, a thermal barrier coating on the piston top surface is being developed to reduce cooling losses. This composite coating consists of a thermal barrier layer made of porous particles and a surface sealing layer that prevents the intrusion of fuel and combustion gases. In this study, we clarified the impact of the coating method on coating strength and the　relationship between the substrate surface properties and adhesion strength for practical application.

Development of a High-Response Thermal Barrier Coating to Improve Fuel Efficiency and Combustion Stability in Gasoline Engines

Hiroya Okada･kazuma Kobayashi･Koji Kawashita (SUBARU)･katsuya Takaoka (Nittera)･Takeshi Tsuda (SUBARU)

A high-response thermal barrier coating has gotten attention as one of the items for improving engine cooling losses. In this report, we investigated the effects of applying a rare-earth composite oxide coating to the piston crown surface on thermal efficiency improvement and combustion stability during cold start and warm-up. Fuel economy improved by up to 1%, and in bench tests simulating cold start and warm-up conditions, the coefficient of variation of IMEP improved by approximately 10%.

Development of a Foot Behavior Evaluation System Based on Automatic Hazard Scene Detection and Foot Joint Tracking

Kazuma Suzaki (Department of Modern Mechanical Engineering, School of Creative Science and Engineering, Waseda University)･Hiroaki Hayashi･Shigeki Sugano (Department of Modern Mechanical Engineering, Waseda University)･Mitsuhiro Kamezaki (Graduate School of Engineering, The University of Tokyo)

Preventive actions that enable immediate response to potential hazards are crucial for avoiding traffic accidents. This study focuses on the driver's right foot movement in preparation for braking. We propose an automatic evaluation method that detects hazardous situations (e.g., passing parked vehicles, driving in parking areas) using a front-facing camera, and tracks foot joint movements using a footwell camera to assess whether and when the foot moves toward the brake. Experimental results showed over 90% agreement with instructor evaluations.

Early Detection of Latent Unsafe Consciousness Based on Dynamic Estimation of Internal Driver State

Hironori Suzuki (Toyo University)･Toshiaki Kimura (Kyoto Tachibana University)･Jun Tajima (Misaki Design LLC)

Many traffic accidents caused by drivers are triggered by observable unsafe behaviors, which themselves may be rooted in latent unsafe awareness or unconscious cognitive states. Understanding and anticipating these underlying states is essential for improving driving safety. This study proposes an algorithm that dynamically estimates the internal state of the driver to detect early signs of latent unsafe awareness before it manifests as atypical driving. The effectiveness of the proposed approach is validated using experimental data collected from a driving simulator under various cognitive and environmental conditions.

Comparative analysis of Japanese and Chinese drivers behavior using the KM safe driving test kit

Masahiro Yamataka (Aichi University of Technology)･Katsuya Matsunaga (Kyushui university (emeritus professor))

This study examines the driving behavior of Japanese and Chinese individuals, assessing the impact of driver’s license possession and nationality on cognitive processing and reaction latency during driving. The KM Safety Driving Test Kit was employed to quantify cognitive load, reaction efficiency, and timing precision. The results indicate that among licensed drivers, Japanese participants exhibited reduced cognitive response times and greater temporal stability compared to their Chinese counterparts. Conversely, among unlicensed individuals, Chinese participants demonstrated accelerated and less variable cognitive reaction times relative to their Japanese peers. These findings suggest that driving experience enhances cognitive decision-making efficiency, while that differences in traffic environments may also influence driving behavior.

Characteristics of Bicycle Driving at Unsignalized Intersections by Non-Driving License Holders

Oto Nagamine･Hiroshi Yoshitake･Motoki Shino (Institute of Science Tokyo)

Since there are many bicycle accidents involving junior high and high school students and the bicycle side is often at fault, there is a need for safe driving assistance for cyclists. In this study, we focused on the fact that junior high and high school students do not have a driving license, and used a simulator to understand the characteristics of bicycle driving by those who do not have a driving license at unsignalized intersections, a scene where many accidents occur.

Investigation of Control Requirements for Maintaining Driving Excitement and Arousal in Level 2 Driver Assistance Systems

Masahiko Kato･Maki Sakamoto･Kenji Tanaka (University of Electro-Communications)

We conducted a study of control specifications to maintain high arousal and ensure safety during highway driving with a Level 2 driver assistance system. Referring to the idea of Russell's Circle Model, we presented control requirements that would achieve both high arousal and driving pleasure during driving by representing the driver's emotions on a plane with two axes: driving pleasure and arousal level.

Consideration of Indicators to Distinguish the Decrease in Attention Resources for Driving
-Capturing the Eye-Centering Phenomenon through Fixation Time-

Hiroaki Ogawa･Katsushi Asami (DENSO)･Takushi Kawamorita (Kitasato University)

We are studying a method to distinguish a state (cognitive distraction) in which the driver is looking ahead but is not sufficiently cognitive and attentional resources for driving are reduced using eye movements.
In addition to the control task of following the moving visual object displayed on the display with the eyes, the n-back task was imposed to reproduce the state of reduced attentional resources. The "eye-centering phenomenon" in which the gaze is located in the center of the visual field was frequently observed.
When this phenomenon was quantified by the fixation time near the center of the visual field, it was suggested that this condition could be distinguished with more than 80% accuracy.

Performance-based evaluation method for detectability of alert signs on vehicle meters display

Tsukasa Kimura･Yurie Shin･Ryuraro Oe (Graduate School of Human Sciences,The University of Osaka)･Masanori Furuya･Tomomichi Uekuri (Nissan Motor)･Kazumitsu Shinohara (Graduate School of Human Sciences,The University of Osaka)

This study investigated vehicle meter display visibility and evaluation methods based on physical display characteristics and the drivers’ knowledge for meter display. The results indicated that visual complexity and location of information placement are critical factors affecting visibility. Furthermore, the results suggested that the proposed experimental method may be an effective method for evaluating the visibility of designed vehicle meters.

Influences of In-vehicle Information Presentation using Animation Display on Drivers’ Behaviors
-Discussion on Information Providing by V2X System on Intersections with Poor Visibility-

Akira Ohtani･Ryohei Homma (JARI)･Masaaki Abe (JAMA)

In this study, we investigated the influences on driving behaviors when animation information about the appearance of vulnerable drivers at intersections with poor visibility was presented to drivers. Based on the results of a driving simulator experiment, the influences of the animated display on driving behaviors and driver distraction were discussed.

Influence of humanoid robot interaction on pedestrian-aware driving behavior

Ayaka Togiya･Hirotaka Yamamoto (Kyoto Institute of Technology Graduate School)･Mariko Osaka (The University of Osaka)･Yukiko Nishizaki (Kyoto Institute of Technology)

With the aim of proposing a new way to use humanoid robots for safe driving support, we examined whether interaction with a robot before driving promotes drivers' empathetic driving behavior. Drivers play a game involving imitation of behavior with a humanoid robot before driving. We examined whether this would lead to differences in the degree to which drivers slow down to give priority to pedestrians at unsignalized crosswalks.

Basic Study on a Method for Estimating Arousal Level Focusing on Physiological Information of Drivers Conversing with Generative AI

Tatsuya Sato･Yuta Ogura･Shunta Takahashi･Komei Hayashi･Hidenobu Takao (Kanagawa Institute of Technology)･Ayumu Kawata･Yusuke Tanizawa･Hiroaki Hashimoto･Rusako Fujino･Nagata Hideki (Pioneer)

In the future, an interactive system that maintains arousal level by interacting with a generative AI is considered useful. To achieve this, it is necessary to estimate the driver's arousal level, but this method has not yet been generalized. In this study, we investigate a basic method for estimating the driver's arousal level based on physiological information using deep learning, especially in the low arousal level range.

Multi-Turn Dialogue with Large Language Model for In-Vehicle Spoken Dialogue Systems

Akinobu Lee (Nagoya Institute of Technology)･Koichiro Karasawa (Toyota Systems)･Atsunobu Kaminuma (International Professional University of Technology in Tokyo)

Dialogue systems based on large language models (LLMs) have been rapidly adopted for in-vehicle user interfaces. However, controlling the amount of information in a LLM-generated response through simple prompting is inherently difficult, thus potentially increases drivers' mental work load. This study examines incorporating several multi-turn, step-by-step strategies into LLM-based spoken dialogue system, aiming to keep user convenience.

Evaluation of a Human Machine Interface for Vehicle – infrastructure Cooperative Driver Assistance at Right Turns at Intersections

Kimihiko Nakano･Jun Sawada･Masaaki Onuki (The University of Tokyo)

This study investigates whether information provided from infrastructure to vehicles in cooperative Level 4 automated driving can also serve as effective driving support. Human-machine interfaces (HMIs) are proposed to convey the presence or absence of obstacles, or right-turn initiation decisions at intersections. Their effectiveness is evaluated through driving simulator experiments.

Evaluation of Driver Acceptance in in-Vehicle Driving Assistance Information Across Various Situations Using Event-Related Potentials

Jongseong Gwak (Takushoku University)･Hiroshi Yoshitake･Motoki Shino (Institute of Science Tokyo)

To evaluate driver acceptance of driving assistance information, we examined central nervous responses when suitable and unsuitable information was presented, focusing on differences across information types. Using a driving simulator and biosignal measurement system, we analyzed event-related potentials. Results showed that P300 peak amplitudes varied depending on the type of information under different suitability conditions.

Simulation of Electric Vehicle Charging Behaviour on Highways Assuming Dynamic Pricing

Takuma Niimi･Tomoko Iwata･Tsuyoshi Yoshioka (Shibaura Institute of Technology)

With the increasing popularity of electric vehicles, supply and demand coordination is necessary to utilise solar-generated electricity for recharging during the daytime, as traffic on highways is concentrated in the morning and evening. In this study, a multi-agent simulation was used to estimate the effect of improving the self-consumption rate when dynamic pricing was introduced for recharging charges, assuming the installation of solar power in service areas.

Development of a new BEV charging and power supply system.

Takumi Kitajima･Shuichi Orita･Yuichi Hosaka･Keisuke Nishida (Nissan Motor)

The spread of BEVs requires improvements in convenience during charging and power supply, as well as the creation of new value. The new BEV adopts a Plug&Charge system, eliminating the hassle when charging. Additionally, leveraging the advantage of a movable battery, we developed a power supply system that allows the charged electricity to be supplied externally, enabling users to enjoy electricity anywhere without being limited by location.

Study on the feasibility of small, low-speed EVs with on-board PV systems

Toshio Hirota･Yushi Kamiya (Waseda University)･Sou Ikeda･Yasuyuki Muramatsu (Yamaha Motor)

A research EV with a photovoltaic (PV) system was constructed and road tests were conducted to clarify the feasibility. A PV panel was installed on the roof of a small-size, lightweight, two-seater vehicle, and EV electric consumption, solar irradiance, and PV power generation were measured and analyzed. A simulation model was developed to estimate the effects of installing PV, such as reduction in electric consumption depending on driving conditions and weather conditions.

The Evolution of Power Unit Development Process through MBD (Sixth Report)
-Improving Fuel Efficiency through Drive Unit Thermal Management-

Takuya Honjo･Rika Kikuchi (Honda Motor)･Mikito Nagata (Meitec Fielders INC.)･Kenichiro Ogata･Keijiro Koide (Honda Motor)

To achieve a carbon-neutral society, improving the fuel efficiency of hybrid power units is essential. For further performance enhancement, the thermal flow of the drive unit needs to be properly designed. Using a 1D drive unit thermal model, the specifications for the thermal management system were clarified, considering the vehicle system performance.

The evolution of power unit development process through MBD (Seventh Report)
-Model acceleration through formulation technology for engine thermal plant models-

Keijiro Koide･Kenichiro Ogata･Takumi Matsumoto･Go Toshizane (Honda Motor)

To enhance vehicle performance through power unit optimization, a 1D engine thermal plant model incorporating design data was developed to satisfy system-level thermal requirements. However, performance verification requires simulating numerous driving scenarios and control calibrations, making computational speed a challenge. This paper introduces a new formulation technique that maintains the accuracy of conventional models and preserves engine component-level temperature prediction, while achieving faster-than-real-time computation. This enables efficient simulation and supports broader scenario coverage, contributing to more effective performance validation and calibration processes.

The Evolution of Power Unit Development Process through MBD (Eighth Report)
-Model construction integrating thermal plant models and its use for control calibration-

Kenichiro Ogata･Takuya Honjo･Rika Kikuchi･Keijiro Koide･Takumi Matsumoto･Go Toshizane (Honda Motor)･Junya Matsumoto (Ryomo Systems)･Mikinori Sato･Yuki Hamatsu (AutoTechnicJapan co., LTD.)･Mikito Nagata (Meitec Fielders INC.)

In order to enhance performance of hybrid power unit, utilization of MBD throughout entire development process is anticipated. While MBD enables development without relying on prototype in early phase, it requires significant resources for control calibration using vehicles during performance verification phase. Therefore, replacement by MBD is necessary. This report constructed integrated model that combined 1D drive unit thermal plant model and engine thermal plant model with a vehicle system model, and implemented virtual calibration with design variables as calibration settings. By conducting multi-objective function and multi-design variable calculations, it was possible to explore calibration settings that maximize performance potential.

The Evolution of Power Unit Development Process through MBD (Nine Report)
-Enhancing Robustness of Energy Management Control for Hybrid Power Units-

Takumi Matsumoto･Kenichiro Ogata･Yuichiro Murata･Yuki Honma･Keiji Tojo･Tetsuya Fukuoka (Honda Motor)･Junya Matsumoto (Ryomo Systems)･Mikinori Sato･Kazuma Inukai (AutoTechnicJapan co., LTD.)

In order to fulfill different customer needs, robust power unit performance that adapts to usage conditions is demanded. The conventional development for the power unit requires a heavy workload and long periods because of vehicle-based robustness verification. Therefore, improvements are necessary. This report focuses on improving development efficiency through MBD. Specific means are transitioning control models to ECU onboard logic and creating scenarios that cover market driving patterns using big data. Conducting robustness verification with combining these with vehicle 1-D system model, we achieved rapid development for the robust power unit performance.

Model-Based Development of Parallel Hybrid System for K-cars

Norifumi Mizushima (AIST)･Kyohei Yamaguchi (Kokushikan University)･Yoichi Iiyama･Yuji Kado (JAXA)

In the previous study, the authors explored the optimized engine geometrical parameters, such as bore and stroke, compression ratio, connecting rod length and intake valve timing, to improve thermal efficiency of K-car engine regardless of the engine displacement standard for K-cars. In this study, the vehicle simulation model and quality engineering tools were linked to investigate the specifications of a parallel hybrid system for K-cars by applying the results of the previous report. This report introduces the methodology of the study and proposes a hybrid system for K-cars that can achieve WLTC (hot) mode fuel economy of 40 km/L.

Study of optimal thermal and power management control for Hybrid Electric Vehicle based on vehicle system 1D simulation model (Second Report)

Yuya Hato･Rinnosuke Hoshi･Wei-Hsiang Yang･Toshio Hirota･Yushi Kamiya (Waseda University)･Kiyotaka Sato (Mazda)

When using the lithium-ion battery in the electric vehicle, it is necessary to take measures against degradation at high temperatures and battery voltage drop at low temperatures. In order to achieve this objective, it is important to control the temperature and power of the battery in an appropriate and efficient manner. In this report, we studied how to manage lithium-ion batterie and thermal system in hybrid electric vehicles under conditions of battery temperature rise at low ambient temperature using a vehicle system 1D simulation model and optimization method.

Study on eco-driving method for BEV on real driving (2nd report: Energy consumption characteristics of light BEV on read driving)

Akira Kato･Hyo Yeon Yoon･Yuki Kumura (Teikyo univ.)

We conducted real driving tests in Utsunomiya City in the summer and autumn using light BEV, and analyzed the correlation between average vehicle speed, AC was on/off, and the frequency of acceleration, deceleration, idling, and cruising, and energy consumption, separately for urban, rural, and highway. We also compared the results with a standard BEV conducted last year to investigate eco-driving methods for light BEV.

The effects of various factors on fuel economy and driving range in a small commercial EV

Hisakazu Suzuki･Kenichiro Koshika･Shota Miyoshi (National Traffic Safety Environment Laboratory)･Tomonori Hasegawa (National Traffic Safety Environment Laborator)

EVs are highly compatible with home delivery and are becoming more and more popular. Although certified values for the driving distance, which is an issue with EVs, are made public, many businesses are concerned about their actual operation. Therefore, evaluation tests were conducted on small commercial EVs to examine the impact of factors that occur during actual operation, such as using air conditioners, on electricity consumption and changes in battery capacity.

Evaluation method development of drive control system function and performance by coupling the chassis dynamo and simulation software (VILS)

Akihiro Terao (Nissan Motor)･Toshiyuki Myochin (Nissan Motor)･Kazutoshi Miwa (Nissan Motor)

The new type of the vehicle evaluation method on the dyno bench has been established to evaluate the complicated electric drive system and improve the control adaption accuracy.
By combining the low-inertia, high-response chassis dynamometer and the vehicle dynamics simulation software, the dyno bench can simulate any type of road conditions.As a result, the new vehicle evaluation method can complete all requested test conditions and achieve the best control parameters adaption with eliminating the variations of road surface conditions that can happen in the normal proving ground test.

Evaluation review of a chassis dynamometer system for xEV testing (Third Report)
-On the purpose of standardizing the performance requirements and evaluation methods of chassis dynamometer test systems aimed at reproducing actual driving conditions.-

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

This report presents the plan to standardize a new methodology and evaluation index as Part 3 of the JASO E018 standard, which specifies chassis dynamometer control requirements and performance evaluation methods for reproducing actual driving fuel economy, electric power consumption, exhaust gas evaluation, and various driving conditions on test benches. This new standardization considers the power characteristics of xEVs (electrified vehicles) to enable high-precision evaluation for these vehicles as well.

Energy Optimization Method for Coordinated Operation of Household and Facility Using EVs and Shared Energy Storage System

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

We propose an energy optimization method for the community including households and a large commercial facility by utilizing EVs and Shared ESS(Energy Storage System). The system assumes that households own EVs, while the facility owns a large-scale photovoltaic system and Shared ESS. By simultaneously optimizing EV transport, charging/discharging, and the trading price of Shared ESS, we successfully achieved a significant reduction in household electricity costs while keeping the facility’s costs suppressed.

Estimation of Airflow in the Vehicle Engine Room and Velocity of Air Passing Through the Heat Exchanger Using Machine Learning

takumi kitsukawa･Kei Akasaka･Fangge Chen･Takuya Nanri･Takehito Teraguchi (Nissan Motor)

To evaluate vehicle thermal performance, Computational Fluid Dynamics (CFD) simulations play an important role, but they are costly and time-consuming. In this study, we propose a surrogate model using machine learning reduce the cost and time associated with CFD. This model estimates airflow in the engine room and the velocity of air passing through the heat exchanger from vehicle shape and airflow resistance of the heat exchanger. We then show the estimation accuracy and the computation time on a self-made dataset, demonstrating the effectiveness of the proposed method.

Research on the Flow Field Structure to Achieve Both Reduction of Snow Adhesion and Aerodynamic Performance.

Motoki Morioka･Masatoshi Saitou･Tomohisa Ueda･Hyuuga Miyazawa (SUBARU)

Focusing on the snow adhesion phenomenon at the rear of the vehicle, we analyzed the mechanisms that lead to snow adhesion. Based on our findings, we optimized the wake structure by controlling the airflow from both the underbody and the roof. This study explored technologies aimed at simultaneously reducing vehicle drag and minimizing snow adhesion.

Development of CAE Methods for Predicting Snow Accumulation on Underfloor Covers During Snowy Road Driving

Tadashi Matsuura･Teruyuki Annen･Shigeki Ueno･Takeyuki Harada･Mikio Asai･Haruyuki Watanabe (Toyota Motor)

The use of resin underfloor covers has become widespread in automotive design to enhance aerodynamic performance and fuel efficiency. However, during driving on snowy roads, snow accumulation poses a risk of damaging these covers, necessitating measures to mitigate this issue. This study employs a particle method for analyzing snow accumulation on the covers and proposes an evaluation technique that contributes to reducing the development time and costs in vehicle development.

Study on influence of on-road wind on vehicle aerodynamics based on airflow analysis around a simplified elevated road

Takuji Nakashima･Ren Hasegawa･Shohei Imagawa (Hiroshima University)･Keigo Shimizu･Takenori Hiraoka･Nakamura Yusuke (Mazda)･Rahul Bale (Kobe University)･Makoto Tsubokura (Kobe University, RIKEN)

Aerodynamic analysis of a general vehicle model for aerodynamic research driving on an elevated road model, including simplified sound barriers and bridge piers, was conducted together with aerodynamic analysis surrounding the modeled road. As a result, an example of the effect of airflow generated by surrounding structures on vehicle aerodynamic characteristics was investigated, and the relationship between airflow phenomena observed on the road and wind direction and speed observed from the vehicle was discussed.

Flow around a Longitudinal Circular/Square Cylinder Moving near the Ground

Yuui Mitamura･Firoz Mohammed RATHORE (Doshisha University)･Tatsuya Inoue (Railway Technical Research Institute)･Katsuya Hirata (Doshisha University)

In order to reveal the ground effect upon vehicles, we conduct wind-tunnel experiments to study the flow on longitudinal circular/square cylinder moving near the ground. As a result, the effect is remarkable at h/D < 1.0, where h and D are cylinder height and diameter respectively. CFD reveals the flow representing the effect.

Investigation of Aerodynamic Drag Differences Caused by Tire Brand Variations and Their Reduction Methods

Yoshiteru Hoshida (Honda Motor)

This study investigates the effect of tire brand variations on the aerodynamic drag coefficient (CD) of the same vehicle. Wind tunnel testing and CFD analysis revealed that differences in sidewall shape are the main cause of CD variation. In particular, the front tire shoulder and cross-sectional profile significantly affect the flow field and contribute to drag differences. Based on these findings, a shape optimization method was proposed to reduce CD variation, and its effectiveness was verified through wind tunnel tests. This presentation reports the mechanism of CD variation and the proposed reduction method.

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

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, we developed a three-dimensional analysis technique employing fluid dynamics. By comparing actual measurements of solar radiation and cabin temperature during outdoor parking with the simulation results, we examined how variations in solar radiation due to seasonal, weather, and temporal factors affect cabin temperature.

Design of battery cooling channel for electric vehicles optimizing object distribution

Yoshikatsu Furusawa･Kunitaka Shintani･Shunsuke Hirotani (Nature Architects)･Kentaro Yaji (The University of Osaka)･Kai Suto (Nature Architects)

Because of growing interest in electric vehicles, demand for developing high-performance battery systems is rising. While the development requires an efficient battery cooling unit, the design optimization of a cooling channel is difficult due to highly non-linear dynamics of fluids. Recently, an optimization method that obtains an optimal object distribution has been proposed for designing efficient cooling channels with good productivity. This study extends the method to the design of a battery cooling plate for electric vehicles.

Evaluation of Equivalent Temperature in Vehicle Cabin by a Mesh-Free Simulation (Fifth Report)
-Evaluation of equivalent temperature under transient cooling condition with solar radiation-

Yoshiichi Ozeki (AGC)･Hajime Oi･Akira Matsumoto (Nissan Motor)

The fifth report focuses on the analysis of the equivalent temperatures under cooling solar radiation transient conditions using a clothed thermal manikin model in a 3D-CAD SUV vehicle cabin by a mesh-free simulation. The calculated results are compared with experiments for an SUV vehicle under cooling transient condition with solar radiation in a climate chamber. The control differences of the clothed thermal manikin on the equivalent temperature are also studied.

Improvement of Steady-State Analysis Accuracy of Blower Fans through Optimization of the MRF Region

Katsutoshi Taninaka･Yusuke Koike･Kanichi Yamaguchi (Mazda)･Takuji Nakashima (Hiroshima University)･Masayuki Shiga･Yuka Kinoshita (Japan Climate Systems)･Keigo Shimizu (Mazda)

In this study, we aimed to reduce the analysis cost of blower fans by focusing on the MRF (Multiple Reference Frame) region to improve the accuracy of steady-state analysis. A high-accuracy model was constructed using unsteady analysis (sliding mesh), and by comparing it with MRF steady-state analysis, we analyzed the factors involved. Based on this analysis, we optimized the MRF region to construct a model that is almost equivalent to the unsteady analysis.

Optimized planned ventilation control based on estimated vapor generation in the vehicle cabin.

Yoshiyuki Takeuchi･Mamoru Fujita (Honda Motor)

To reduce the energy used for heating in electric vehicles and address the decrease in driving range during winter, we developed a target ventilation control system that estimates the amount of vapor generated inside the cabin using existing sensors, enabling the minimum necessary ventilation without any cost increase. This technology was first applied to PHEV vehicles and has since contributed to reducing heating power consumption in various types of electric vehicles.

Application of Numerical Boiling Heat Transfer Model to Pin-Fin Heat-Exchanger

Yoshiki Tanaka･Takaya Sato･Takeshi Ooyama (DENSO TECHNO)･Yukinori Hamaji･Masayuki Tokitani (National Institute of Fusion Science)･Yoshiyuki Tsuji (Nagoya University)

As the expectation for boiling cooling increases in response to high heat generation density of devices, there are few examples of numerical analysis and experimental verification of boiling heat transfer in mass-produced finned heat exchangers. This study aims to validate the accuracy of numerical analysis using existing boiling heat transfer models by comparing results with convective boiling experiments conducted in a pin-fin channel, a representative example of finned heat exchangers.

Utilization of the 1D Vehicle Model for the Development of the Thermal Management System for Battery Electric Vehicles

Motomasa Iizuka (SOKEN)･Tetsuma Takeda･Takayoshi Kojima (DENSO)

As part of our efforts to address the challenges of extending the range and reducing the charging time of Battery Electric Vehicles (BEVs), we have developed an environment where the performance of vehicles in the development stage can be estimated using a 1D vehicle model. This report presents a case study of its application to winter heating scenarios.

Self-decomposition evaluation of R-1132(E) mixed refrigerants

Takashi Usui･Tomoyuki Goto･Yasufu Yamada･Tomohito Inoue･Aoi Yamaguchi･Yasutaka Negishi (Daikin Industries, LTD.)

We have developed HFO refrigerant R-1132(E), which is low GWP and efficiency, and proposed blend refrigerants R-474A and R-479A. R-1132(E) has a characteristic of self-decomposition in the presence of an energy source, so we reported the boundary of self-decomposition and results of arc discharge energy inside a compressor at 2024 JSAE congress(autumn). In this paper, the effects of temperature, pressure, ratio, and energy source for the occurrence of self-decomposition, are examined in detail.

Modeling of short circuits and arc discharge energy prediction in automotive electric compressors

Kengo Nagai･Yota Omizu (Nagoya University)･Yasutaka Negishi･Tomoyuki Goto･Takashi Usui (Daikin Industries, LTD.)･Koichi Shigematsu･Jun Imaoka･Masayoshi Yamamoto (Nagoya University)

The HFO refrigerant R-1132(E) has low GWP and high performance, but self-decomposition occurs when external energy is input.In this paper, we used measured compressor parameters to simulate the arc discharge energy during a short circuit that induces self-decomposition.We also compared the amount of energy with actual measurements to verify its validity.

Development of High Power Density Motor – Part 1: Design and Analysis

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

This study reports design and analysis results for the development of high power density motor.
The design concept aimed at achieving world-standard power density is presented, along with performance predictions based on electromagnetic and thermal analyses.
Furthermore, the effectiveness of simulations is validated by incorporating experimental evaluation results.

Development of High Power Density Motor – Part 2: Experimental Verification

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

This paper reports the performance evaluation of high power density motor prototype based on design and analysis results. The testing methods and measurement environment are described, and evaluation results for performance characteristics, efficiency, and temperature distribution are presented.
Furthermore, issues observed during testing and the actual motor behavior are discussed, verifying consistency with the analytical results.

Development of High Power Density Motor – Part 3: Discussion and Optimization

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

This paper presents a discussion on the evaluation results of the prototype motor and further design optimization. Specifically, cooling performance is verified through a comparison of oil flow visualization results and analysis outcomes, followed by the identification of issues. Based on these insights, design improvements are proposed, and the outlook for realizing next-generation high power density motors is presented.

Development of Rotary-Fin Air-Cooling Technology for Small EV

Tetsuya Suto･Akeshi Takahashi (Astemo, Ltd.)･Makoto Ito (Hitachi)

We are developing an air-cooled outer-rotor direct-drive system for small cars and motorcycles with strict cost constraints. This drive system dissipates heat of motor losses from the rotary fins installed on the side of the rotor housing, achieving a continuous output of 5.5kW, which is top-class in air cooling. In this presentation, we report on the concept of this cooling structure and the test results.

Development of Two-Motor Electric AWD(All Wheel Drive) System for Minivans

Shuhei Tajima･Eigo Sakagami･Hiroki Shimoyama (Nissan Motor)

Nissan Motor has consistently pursued high response, strong, seamless, and high quality driving performance for its electric vehicles. In the development of the electric AWD(All Wheel Drive) until now, the development goal is to make the AWD enjoyable and comfortable to drive by further improving the power and high quality driving of Nissan's electric vehicles not only on snowy roads but also on all road surfaces and situations, by combining the control technology as AWD with the electric drive motor control technology cultivated from the development of electric vehicles, utilizing the merit of 100% electric drive and independent drive of front and rear wheels.
In adopting this AWD system for the first time in a minivan, we developed a minivan with a heavier vehicle weight than a conventional SUV to maintain the strength as an AWD and a sense of security on snowy and rough roads, and to maintain a flat vehicle attitude in which the occupant does not easily get motion sickness even in a minivan with a large change in pitch behavior by optimizing the front-rear driving force with an emphasis on the riding comfort and comfort of the occupant in the rear seat.

High Performance Inverter for an Electric Vehicle with a Newly Developed Double-sided Cooling Power Module

Kazushige Namiki･Kouichi Matsuda (Nissan Motor)･Yuta Numakura･Shuichi Shinohara･Shoya Awamori (Astemo)･Yu Ebihara (Jatco)

This paper describes the specifications of a newly developed inverter system and the features and effects of the technologies adopted. New technologies such as a double-sided cooling power module using thermosetting thermal interface material, a split-arrangement DC bus capacitor, a 3-in-1 structure that shares the housing with the motor and reducer have been used to improve current performance and reduce losses, without increasing mass, compared to the previous model.

Development of EV Powertrain and Battery for the Third Generation LEAF

Sho Maruyama･Kenichiro Gunji･Kazuya Nitta･Masato Nakajima (Nissan Motor)

Nissan was the first in the world to sell the mass-produced electric vehicle "Nissan LEAF“ in 2010 and the second generation was introduced, improving driving range and driving performance in 2017. While EVs have negative aspects compared to petrol and hybrid vehicles regarding driving range and charging time, they provide customers with the unique appeal of EVs through seamless acceleration and quietness, thanks to the characteristics of electric motor. In developing the new third-generation LEAF, we are adopting new development battery systems, a compact integrated electric power unit (3in1), and a bidirectional onboard charger.
To enhance the driving range and charging performance of EV, we are adopting a “Big module” that improves capacity density and charging performance by revising the battery's electrode materials and increasing the efficiency of cell installation. In the development of a compact integrated electric power unit (3in1), we are enhancing rigidity and achieving compactness by sharing the housing for the inverter, motor, and gearbox. This contributes to improvements in NVH performance, realizing unprecedented quietness, while also enhancing efficiency to contribute to the driving range. Additionally, the development of a new bidirectional onboard charger allows the normal charging port not only normal charging but also to provide power supply functionality, achieving appealing features unique to EVs. We would like to report on the details of this technological development.

Study on Slip Ratio Estimation Method for In-Wheel Motor Driven Vehicles Based on Angular Velocity Response to Sensing Torque

TOSHIYUKI AJIMA･Masaru Yamasaki (Astemo)･Wataru Hatsuse (Hitachi)

This paper presents a slip ratio estimation method in which a small-amplitude sensing torque, designed not to affect vehicle speed, is superimposed on the steady driving torque during vehicle operation. The slip ratio is estimated based on the resulting variations in tire angular velocity. The estimation formula is revisited and refined, and the validity of the proposed method is evaluated. Furthermore, the effectiveness of vehicle speed estimation based on the estimated slip ratio is also demonstrated.

A Study on the Development, CAE Analysis, and Test Validation of a Cell Frame Assembly Module for Advanced Battery Systems

GeonHee Cheon･Gun In･NamJin Kim･DongHoon Kim･JungSub Kim･Hyun Sung (SeoJin Industrial)･GyuHo Shim (ECOPLASTIC)

This study presents the Cell Frame Assembly Module, an integrated structure combining the chassis frame and battery case to enhance EV performance. Replacing aluminum with steel and optimizing the layout improves structural integrity, reduces cost, and expands battery space for longer range. Virtual analysis (vibration, fatigue, impact, cooling) and prototype testing confirmed performance. A form gasket and new bolt-sealing structure ensured IP67 level sealing. This integration simplifies manufacturing, maximizes space, and enhances competitiveness. The paper details CFAM's design, CAE methodologies, and validation tests, offering practical insights for next generation EV platforms.

Experimental research on fire prevention involving electric vehicles (1st report)

Yoshihiro Sukagawa･Koji Yamazaki (JARI)

While the global adoption of electric vehicles (EVs) has been accelerating rapidly in recent years, addressing the risk of fires caused by thermal runaway in the high-voltage batteries installed in these vehicles has become a critical issue. Although EVs are generally considered to have a lower risk of fire compared to gasoline-powered vehicles, when a fire does occur, it tends to cause significant damage. It has also been reported that extinguishing fires involving high-voltage batteries requires a large volume of water and a prolonged period of time. This risk is particularly heightened following vehicle collisions, as battery damage increases the likelihood of fire. Therefore, special precautions must be taken when storing EVs after a collision.
In this report, we investigate one potential countermeasure for post-collision storage of EVs: covering the entire vehicle with a fire-resistant sheet (fire blanket). We experimentally evaluated the effectiveness of this method.

A Study on the Development of Predictive Method for Structural Weakness of Bus Body in Concept Stage Using 1D Beam Model and Machine Learning

gyuhee kim (Hyundai Motor)

This study proposes a machine learning-based model that estimates joint strength levels using 1D simulation data, eliminating the need for 3D modeling. By leveraging the correlation between 1D and 3D analysis data, the model enables early-stage strength evaluation without detailed CAD or 3D construction, significantly reducing time and cost. The model was validated using domain knowledge, focusing on vulnerable joints. The process, which previously took weeks, was shortened to under an hour with over 80% accuracy. Future work includes expanding training datasets and developing features to enhance accuracy by incorporating diverse joint characteristics.

A Study on Suspension Input Load Prediction using RNN-based Virtual Sensor for Durability Application

SEUNGWAN SON SON･DAEJIN KIM (Hyundai Motor)

In this study, a method was developed to predict wheel input forces and suspension component input loads without wheel force transducers and suspension load cells. For the development and verification of the process, a set of training data was acquired by measuring the wheel forces and the suspension forces in one vehicle. Subsequently, a training model was created using the Recurrent Neural Network model. Finally, the wheel force and suspension load were predicted using a vehicle equipped with a low-cost single Inertial Measurement Unit, and the model performance was verified by comparing the predicted values with the measured data.

Efficient Optimization of Component Placement Using Replica Exchange Method

Koichi Seki･Masaya Michishita･Hideaki Bunazawa (Toyota Motor)

Efficient placement of components in vehicle development is crucial for performance enhancement and cost reduction. This study applies the replica exchange method to the placement problem of dummy components, comparing it with traditional hill-climbing and simulated annealing methods. The results demonstrate that the replica exchange method enables more efficient optimization, achieving improved component placement.

Optimization of Frame Cross-Sectional Shapes Using Kernel QA

Wataru Shimoda･Toshiki Kondo･Takehisa Kohira (Mazda)

In recent automotive development, the rapid increase in design parameters necessitates the practical application of efficient optimization techniques such as Quantum Annealing (QA). In this study, we optimized the cross-sectional shapes of automobile frames using QA, and applied kernel regression to reduce computation time. Additionally, by refining the binarization process, we achieved improved the performance even with finer discretization.

Prediction Technology Development for Millimeter Wave Radar Transmittance with Paint Composition in New Color Development.

Naoya Osaki･CHEETUCK HO･Hironori Tsutsui･Keiko Ukishima･Natsuko Kaji･Tomoyuki Okamoto (Nissan Motor)

With the proliferation of ADAS vehicles, radar transmittance of coatings has become a critical issue. Traditionally, coating evaluation was performed through measurements after paint development, leading to development rework if composition changes were necessary. To address this, we developed a technology that simulates radar transmittance from paint composition. This innovation allows for early evaluation of coatings before the completion of paint development.

Development of a Simulation to Estimate Emergency Transport Time and Its Simplified Method

Shinji Asakura･Heishiro Toyoda･Tomoyuki Miyoshi･Hiroto Kawano･Takashi Moriuchi･Shinji Yamagiwa･Maria Yasuda (Toyota Motor)

The emergency transport time has been increasing year by year, and there is a desire to reduce this transport time. One potential approach to study how we can shorten emergency transport times is to use traffic flow simulations. In this study, we developed a simulation model for emergency transport. Additionally, we developed a simplified estimation method to reduce the time needed to prepare the emergency driving model for future studies and to expand the options for routes being considered for emergency driving.

Analyzing the Discrepancy Between D-Call Net Based and Kinematics-Based Delta-V

Noboru Tanase･Shizue Katsumata･Takahiro Ando･Yasushi Nagaoka (Toyota Motor)･Mayu Ishii (Institute for Traffic Accident Research and Data Analysis)

D-Call Net constructs mortality risk curves based on pseudo ΔV calculated from accident data, while actual reports use the airbag ECU's ΔV to calculate mortality rates. Both ΔVs generally align in translational motion but may differ in rotational accidents. By matching accident data with D-Call reports, the differences in ΔV and their causes are analyzed.

Study on actual situations of D-Call Net by matching automatic notification data with ITARDA Macro data

Toru Kiuchi (ITARDA)･Nobuo Saito･Ichiro Ando (JAPAN MAYDAY SERVICE)･Mayu Ishii･Eiko Kagesawa (ITARDA)

In recent years, the number of automatic notifications has dramatically increased due to the spread of vehicles equipped with D-Call Net. The authors were able to obtain notification data from three new OEMs in addition to the existing one. Therefore, we conducted a new effect study by matching the most recent notification data from 2021 to 2023 with ITARDA macro data. Again, as in the previous study, the focus was on single-vehicle accidents.

Utilization of image recognition for pedestrian injury prediction considering vehicle collision areas.

Mie Tokuyama･Takahiro Andoh･Noboru Tanase･Shizue Katsumata (Toyota Motor)･Kohji Ichikawa (Toyota Technical Development)

To reduce traffic accident fatalities, early medical intervention is essential. This requires a higher accuracy in predicting human injuries. In this study, we will focus on pedestrians, who account for the highest number of traffic deaths. In addition to traditional collision speed, we will use the height of pedestrians and the vehicle collision areas measured by image recognition for the injury prediction algorithm.

Development of a Collision Detection Model Using Dashcam Audio Information (1st report)

Yuki Nomura･Shouhei Kunitomi･Yoshihiro Sukegawa (JARI)･Yasushi Nagaoka (JAMA)

This study developed a machine learning model for detecting collisions with passenger cars and vulnerable road users or motorcyclists using audio data recorded by dashcams. The model successfully detected 72 collisions out of 79 test data based on the audio data during the collisions. The analysis also discussed factors contributing to false detection and non-detection.

Numerical Modeling for Control to Achieve Early Activation of Urea SCR Catalysts by Electric Heating

Hayato Kojima･Reon Aoki･Tomoki Sakurai･Jin Kusaka (Waseda University)

An electrically heated catalyst (EHC) was installed in front of the SCR catalyst to improve the NOx conversion rate by increasing the temperature of the exhaust gas. Based on the characteristics of the exhaust gas, such as flow rate, temperature and composition, a numerical model for control was developed to calculate the power applied to the EHC required to bring the exhaust gas at the SCR catalyst inlet to the target temperature. The model enabled to raise the temperature of the exhaust gas with a maximum error accuracy of 3%.

Concept and Verification of Cold Emission Reduction Technology through Exhaust Path Reaction Control

Xiyao Ge･Ran Nishikido･Yoshitomo Takahashi･Tsugio Fukube･Daichi Takashima (Mazda)

Against the backdrop of stricter emission regulations, reducing emissions during the initial cold start phase when the catalyst is inactive has become an urgent task. In this study, we conceptualized a technology to control the temperature and concentration fields within the exhaust path to promote oxidation reactions. Through single-cylinder engine tests, we confirmed that this technology has the effect of reducing HC, CO, and NOx emissions by 70-90% compared to conventional methods.

Study on the Post-Oxidation Mechanism of Unburned Hydrocarbon Species inside the Exhaust port and manifold of Gasoline Engine.

Masahisa Yamakawa･Tatsuya Fujikawa･Daisuke Shimokuri･Keisuke Yamamoto (Hiroshima University)･Kenji Uchida･Jyunki Hori･Naoki Yoshioka･Kaede Shirane (Mazda)･Akira Miyoshi･Yoshiki Sho (Hiroshima University)

In order to achieve zero emissions of harmful substances (Zero EM), it is necessary to reduce not only unburned hydrocarbons (HC) during cold starts but also the intermittently emitted difficult-to-clean HC from the latter half of the catalyst warm-up process. Therefore, we introduced technology to measure the gas components and temperature inside the exhaust pipe with high time resolution to analyze their generation and post-oxidation. We investigated the effects of mixture formation and other factors on these emissions.

Proposal of a Compact Aftertreatment System Integrating Exhaust Gas Adsorption, Conversion and Particle Filtration Functions

Masashi Matsumoto (JARI)･Katsunori Hanamura (Sophia University / Japan Science and Technology Agency)･Takashi Ogi (Hiroshima University)･Kohei Kume (Waseda University)･Masahiko Matsukata (Waseda Univeresity)･Takaaki Kitamura (JARI)

An exhaust aftertreatment system with high performance and compact is required to meet stringent emission regulations and to reduce installation space. In this research, we have proposed a functionally integrated exhaust aftertreatment structure, in which three-way catalyst particles and hydrocarbon absorbent particles are layered on a wall-flow monolith. In this report, a concept of exhaust gas purification of this aftertreatment structure was demonstrated, and various results for further improvement of performance were introduced.

Experimental Analysis of Ammonia Generation Characteristics by Heated Urea Water Solution Spray in SCR Systems

Tetsu Ishii･Kengo Nakagawa･Eriko Matsumura (Doshisha University)

In SCR systems under low exhaust gas temperature conditions, the urea is not decomposed to ammonia completely and the NOx purification rate decreases. In this study, the effects of urea water solution heating control on ammonia production under low exhaust gas temperature conditions through experimental analysis are reported.

Hardening mechanism of gasoline deposits
-Viscoelastic behavior of deposits under thermal cycling conditions-

Yoshinori Nakayama･Takumi Suzawa (SOKEN)･Tomoharu Kataoka (Toyota Moter Corporation)

It has been demonstrated that gasoline deposits, which were previously believed to harden only at temperatures above 110°C, gradually harden even at 100°C when subjected to repeated heating. Furthermore, the viscoelastic behavior of these deposits indicates that they exhibit thermoplastic properties. Additionally, the mechanism by which these deposits harden through repeated heating has been examined.

Study on Modeling of Combustion Chamber Deposits in High-Efficiency Gasoline Spark-Ignition Engines (First report)
-Accelerated Formation of Combustion Chamber Deposits Using a Spark-ignition Engine-

Kazuma Motohashi･Takumi Nakajima･Kento Okusa･Satoshi Sakaida･Kotaro Tanaka･Mitsuru Konno (Ibaraki University)･Koichi Kinoshita･Yohko Abe (AIST)･Satoshi Kodama･Shinsuke Mori (Institute of Science Tokyo)

With the introduction of high-efficiency combustion technologies, unexpected formation of combustion chamber deposits (CCDs) has led to issues such as abnormal combustion due to increased compression ratio and deterioration in emissions. To develop a predictive model for CCD formation, accelerated deposit formation experiments were conducted using a spark ignition engine. Through these experiments, the formation process of combustion chamber deposits was elucidated.

Study on modeling of combustion chamber deposits in high-efficiency gasoline spark-ignition engines （Second report）
-Elucidation of the formation mechanism of combustion chamber deposits using an autoclave-

Koichi Kinoshita･Yohko Abe (AIST)･Kotaro Tanaka･Satoshi Sakaida･Mitsuru Konno (Ibaraki University)･Shinsuke Mori･Satoshi Kodama (Institute of Science Tokyo)

To improve thermal efficiency and reduce CO₂ emissions in passenger vehicles, a range of advanced combustion and fuel technologies are being investigated. However, the formation of combustion chamber deposits (CCDs) remains a critical challenge, as it can lead to engine knocking and other negative engine performance. This study aims to clarify the mechanisms underlying CCDs formation, establish effective suppression methods, and construct a predictive model. To this end, experimental analysis was conducted using both simulated deposits and samples obtained from actual engines, allowing for the identification of key contributing factors to deposit formation.

Reliability Impact Study of Printed Wiring Board Manufacturing Quality in Support of the SDV Era

Natsuki Kumagai･Tai Horikawa･Norimitsu Sakai (Nissan Motor)

With the evolution of electric vehicles and the shift towards Software-Defined Vehicles (SDVs), the sophistication of electronic devices supporting driving functions is advancing. While the circuits of printed wiring boards (PWBs) are becoming more complex and high reliability is required for 24-hour operation, the relationship between PWB manufacturing standards and reliability remains unclear. This study quantitatively verified the relationship between PWB manufacturing quality parameters and reliability.

Redefining Moisture Resistance Lifetime Design and Moisture Resistance Testing for Printed Circuit Boards in the Era of SDV

Tai Horikawa･Natsuki Kumagai･Shunsuke Narita (Nissan Motor)･Masatoshi Ando･Kazuya Okada･Masayuki Shimura･Takeshi Yoda･Takenori Kakutani (Taiyo Ink Mfg)

The high temperature and humidity bias test is a standard evaluation for electronic devices; however, its definitions as a durability or quality assurance test are ambiguous, and the methods for determining test specifications remain unclear. This study redefines the positioning of the test and establishes a lifetime design methodology for PCBs. Additionally, it derives a general model of material degradation from test results and prior research, demonstrating the continuous relationship between the Arrhenius model and physical laws.

Consideration of circuit models for in-vehicle printed circuit boards

Yukihiro Serizawa (Sohwa & Sophia Technologies Inc.)

Model-based development using CAE and simulation is progressing as a technology for predicting EMI test results. Printed circuit boards in many automotive electronics units have complex structures and become increasingly dense, and they change depending on external connections and exterior metal structures, making it difficult to create circuit models and electromagnetic field analysis models. This report introduces the outlook for practical use based on modeling of basic structures and examples of prediction.

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

Jun Muto･Hisao Nishimori･Junya Maeda･Miiyu Orinaka･Yasufumi Shibata･Takashi Yamada (Toyota Motor)

In recent years, high-speed data transmission in automotive electronic components has advanced, leading to the use of connectors with various shield housings. This paper reports on the observed cases of whisker formation from Sn plating applied to the shield housings and investigates the mechanisms behind their growth. Additionally, it proposes potential countermeasures based on the test results.

Analysis of solder peeling phenomenon in high-density electronic components and proposal of design guidelines

Yasufumi Shibata･Hisao Nishimori･Akihiro Yamagata (Toyota Motor)

As in-vehicle electronic components have become more sophisticated, ECUs are becoming more densely mounted. However, due to a mismatch between the internal structure of the circuit board and the solder material properties, peeling of the solder joints may occur during the reflow process. This study reports on an analysis of the mechanism behind the peeling of solder joints, and on guidelines for selecting board structures and solder materials for high-density packaging.

Optimization of ECU connector pin signal assignment using quantum-inspired technology

Toshiki Terabe･Daisuke Ibata･Hiroshi Yoshimoto･Yoshinori Suga (Toyota Motor)･Shinji Iwane (Fujitsu)

We have developed a technology that automates the signal assignment to ECU connector pins using a quantum-inspired technology called Factorization Machines with Quantum Annealing (FMQA). The introduction of this technology has significantly streamlined the signal assignment process, which previously required considerable time from skilled personnel, allowing it to be completed in a much shorter time.

Gate Driver CMTI Verification Model Development and Precautions for Power Electronics　MBD Development
-CMTI Verification model in VHDL-AMS-

Noboru Takizawa (consultant)

A gate driver is always used to drive a power device. Gate drivers must adhere to the CMTI specification. This requires that there is no CMTI verification model, and that the verification be performed including SiCMOS, load models, and parasitics on the peripheral circuits and board. This time, we will announce the points to note and the verification model for this verification

Time-series spectrum analysis of spark discharge and flame in hydrogen spark ignition engine

Kotaro Shimizu･Nobuyuki Kawahara･Yoshimitsu Kobashi (Okayama University)･Satoaki Ichi (Kawasaki Motors, Ltd.)･Koichiro Matsushita (Honda Motor)･Tomohiko Kamio (Yamaha Motor)･Yoshinari Ninomiya･Makoto Kaneko (Suzuki Motor Corporation.)

The objective of this study was to investigate changes in the plasma state during the process from spark discharge to combustion in a hydrogen spark ignition engine. In a compression-expansion engine using hydrogen as fuel, we simultaneously employed a fiber optic spark plug and a Cassegrain optics to obtain the time-series emission spectra from spark discharge to combustion. We detected emissions of OH and N2 and confirmed changes in the plasma state.

Study of flame propagation and quenching characteristics of premixed turbulent flames with Karlovitz number

DAI MATSUDA･Hiroshi MAEYAMA･Ekenechukwu Chijioke Okafor･Toshiaki Kitagawa (Kyushu univ.)

The purpose of this study is to control premixed turbulent combustion in spark-ignition engines. The flame propagation and quenching characteristics of premixed turbulent flames for various fuels (pentene, ethanol, and isooctane) were summarized using turbulence intensity and laminar burning velocity. In addition to the ratio of laminar burning velocity and turbulent intensity, the Karlovitz number was used to explain the quenching process.

Evaluation of reaction and mixing characteristics of near-wall gases based on micro gas sampling and numerical analysis in spark ignition engine

Yuji Tagaya･Tsuyoshi Nagasawa･Hidenori Kosaka (Institute of Science Tokyo)

To elucidate the flame quenching mechanism in spark ignition engines, this study applied a micro gas sampling system to a premixed propylene/air combustion field formed inside a Rapid Compression Machine (RCM) and conducted near-wall micro gas sampling. Based on the measured near-wall gas composition measurement values and numerical simulations, the reaction mechanisms and mixing characteristics of near-wall unburned and burned gases were investigated.

A Study on Ion Current of Carbon-free Fuel Reciprocating Engine

Kouichi Muneo･Mitsuhiro Izumi･Tsutomu Kusuhara･Hiroyuki Kimura･Akihiro Yamao･Kou Wada (Diamond & Zebra Electric)

Hydrogen and ammonia are attracting attention as carbon-free fuel and expected putting into practical use. However, these unique combustion characteristics complicated stable combustion. As combustion detection technology for addressing the issue, ion current detection is exemplified. In this study, ion current of hydrogen and ammonia combustion is evaluated the possibility of combustion control.

Study on Ignition and Combustion Characteristics for Ammonia-Fueled Spark Ignition Engine

Ryota Yamada･Shunsuke Kasuga･Hiroyuki Sakai･Takeshi Hashizume (Toyota Motor)

Ammonia is attracting attention as a next-generation fuel for internal combustion engines toward carbon neutrality. However, its low combustion rate and other characteristics make its combustion range narrow. Expansion of combustion range is required for its application to spark ignition engines. In this study, physical indices showing the ignition and combustion characteristics of ammonia were developed by combustion analysis and CFD of a single-cylinder engine, and directions for expanding the combustion range were obtained.

Laminar Premixed Combustion Characteristics of Ternary Fuel Mixtures of Methane, Hydrogen, and Carbon Dioxide

Wataru Nishio･Takuma Kobayashi･Taketoshi Shimizu (Waseda University)･Kei Yoshimura･Satoru Tokuhara (Suzuki Motor)･Jin Kusaka (Waseda University)

From a carbon-neutral (CN) perspective, compressed natural gas (CNG) and hydrogen compressed natural gas (HCNG), which mixes green hydrogen with CNG, are attracting attention. In order to put these fuels into practical use in society, it is necessary to understand their combustion characteristics. In this study, we clarified the effect of fuel composition on laminar combustion characteristics by visualizing combustion using a constant volume chamber.

A study of combustion-induced vibration in a single-cylinder diesel engine through modal analysis and dynamic behavior analysis

Daichi Yamane･Karin Aoyagi･Masato Mikami (Graduate School of Sciences and Technology for Innovation, Yamaguchi University)

In engines, the combustion impact transmits through each component, decays and finally radiates as noise from the outer surface. We focused on the internal transmission path of the combustion-induced vibration via the piston, connecting-rod and crank shaft and conducted a modal analysis and dynamic behavior analysis. From these results, we discussed frequency characteristics of vibration acceleration result obtained by measuring a single-cylinder diesel engine.

Mode Vector Control of Powerplant Eigenmodes Using Concentrated Masses for Engine Sound Quality Enhancement

Keizo Konishi (Honda R&D)･Kenji Torii (Honda Motor)･Hideto Tamaki (Auto Technic Japan Co., Ltd.)

In our previous study, we proposed structural design guidelines for improving power plant eigenmodes with the aim of efficiently enhancing the sound quality of engine combustion noise. This paper investigates structural configurations that satisfy those guidelines. Specifically, we report the results of evaluating a simplified structural model simulating a power plant, in which the nodal positions of its eigenmodes were adjusted to develop a structure that enhances sound quality.

The Improvement of NVH Evaluation Method through The Development of Simulation Technology to Realize The Vibration Effect of A Power Plant Suspended by Mounts on 3-axis Transmission Test Bench

Shoichi Ishigaki･Hajime Fujimura･Hiroshi Sho･Hiroaki Sumitomo･Hiroki Kuwamoto (Toyota Motor)

The evaluation of a transmission, such as NVH (Noise, Vibration, Harshness), is conducted on a 3-axis test bench before vehicle testing. However, since the transmission is fixed due to the bench structure, the test cannot be conducted with the vibration effects of a power plant suspended by the mounts on the bench. As a solution, we developed the control technology that simulates the vibration effects of the suspended power plant using a model, thereby realizing the effect on the bench.

Simplified Method to Create Vehicle Sound Model for Road Traffic Noise Prediction

Ayumu Yanagibayashi (Kanagawa University Graduate School)･Yoshihiro Shirahashi･Kai Kurihara (Kanagawa University)･Hiroyuki Houzu (NALTEC)･Toru Yamazaki (Kanagawa University)

Prediction of road traffic noise requires a noise model for each vehicle with different noise regulation. In this study, we proposed a method to construct a noise model based on noise regulation values for each regulation category, and validated the road traffic noise LAeq estimation.

Development of NVH Design Technology for High Combustion Speed of 3rd-Generation 100% Electric Drive Hybrid Powertrain

Shinpei Kondo･Hiroshi Matsuo･Tsuyoshi Kozima･Yoshihide Kawasaki (Nissan Motor)

High combustion speed for thermal efficiency improvement is generally trade-off with engine noise.In the newly developed powertrain, while improving fuel consumption by increasing combustion speed, achieve top-level quietness by the exciting force reduction reconsidering the engine main moving body structural system and lighter weight,higher rigidity of whole module, and solve trade-off.

Quietness development of a new electric vehicle with a third-generation e-POWER unit

syuuichi Etori･Takayuki Miyakawa･Shinichi Suganuma･Yukihiro Mori (Nissan Motor)

Third-generation e-POWER unit was developed to balance between high efficiency and low noise by high-speed combustion and 5-in-1. This paper introduces the evolution of the e-POWER unit and the technology development to apply to the vehicle from quietness point of view.

Development of integrated 3-in-1 ePT and dedicated EV platform for PT NVH improvement

Kazuhiko Arai･Hiroshi Matsuo･Tsuyoshi Kozima･Yasuyuki Asahara･Akihiro Hisada (Nissan Motor)

In the electric vehicle (EVs) with high quietness, the importance of the noise and vibration performance of the electric power train (ePT) is increasing. Although having continued to receive high evaluation before, in order to make customers feel more attractive, a top level of quietness has been realized by the development to make 3-in-1 lightweight and high-rigidity and to make EV Platform Optimized for ePT System.

Development of quietness for next　generation electric vehicle with 3in1 unit

Yoshihiro Ando･Takayuki Miyakawa･Shinichi Suganuma･Yukihiro Mori (Nissan Motor)

This paper introduces the technology to improve the quietness of the next generation electric vehicle with 3in1 unit on the platform for electric vehicle. Compared with previous model, it has evolved by sound insulation performance, and improved such as powertrain noise performance by applying to "high-rigidity platform" "high-performance anti-vibration system" and "3in1 unit".

Sensitivity Characteristics of Driver’s Body Regions to Airflow Stimulation in Thermal Environment

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

Airflow stimuli in the vehicle cabin are sensed through sensory receptors and affect the driver's sense of thermal comfort. In addition, the number of sensory receptors varies depending on the part of the body, and the sensitivity characteristics differ depending on the part. Therefore, in this study, in order to realize a thermal environment that is comfortable and maintains arousal, we investigated the sensitivity characteristics when airflow stimuli are blown onto the forearms, back of the neck, and lower legs.

Structure of Model to Quantify Psychological Aspects of Tactile Feedback of Switches (Second 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 the previous report, the necessity to consider differences in individual preferences was indicated. In this study, we classified examinees by clustering based on subjective evaluation results of tactile feedbacks. As a result, we constructed multiple regression models showed correlation between tactile feedbacks and mechanical properties for each cluster.

Study on extraction of sensory evaluation words for automobile steering systems using evaluation grid method

Yudai Hoshino (Graduate School of Sophia University)･Shoichiro Takehara (Sophia University)･Katsunori Tanaka･Ryo Nakada (Nissan Motor)

Steering behavior is an important factor for comfort in automobiles. In this study, we attempted to extract evaluation factors for the psychology of steering by passengers by using the evaluation grid method, in which a driving simulator is used to perform driving where factors related to steering are varied. From the obtained evaluation structure, we extracted the evaluation words related to the sensibility of automobile steering systems.

Quantification of Straight-Line Stability Using a New Approach
-Application to Chauffeur Car Development-

Toshiki Morita･Nagataka Sassa･Tomoyuki Katayama･Nobuaki Minami (Toyota Motor)

Based on sensory comments and vehicle data, we are continuing performance development. However, discrepancies in perception among stakeholders persist, making the quantification of sensory evaluation metrics a long-standing challenge. We focused on quantifying straight-line stability, essential for driving performance, with the full cooperation of skilled evaluators, emphasizing head movements related to sensory perception. We also applied this in a project.

Development of a Measurement System for Steering Operation and Grip Forces Toward Objective Evaluation of Steering Feel

Hideaki Shibue (S&VL)

Steering feel is an important factor that affects vehicle drivability and comfort, and its objective evaluation requires quantitative measurement of the mechanical interaction between the driver and the vehicle. In this study, we developed a system that can measure steering wheel operating force and grip force with high accuracy and responsiveness by optimizing the sensor configuration, layout, and calculation method.

Effects of Video Viewing and Reflection on Reducing Driving Anxiety in Novice Drivers

Yukiko Nishizaki･Chihiro Shumiya･Hajime Yoshida (Kyoto Institute of Technology)･Shin Hirano (Panasonic Holdings)･Motoyuki Okayama (Panasonic Automotive Systems)･Yukihiro Morita (Panasonic Holdings)

This study aimed to reduce driving anxiety in novice drivers by examining the effects of video viewing before and after driving through a driving simulator (DS) experiment. The results showed that watching instructional videos prior to driving as a form of pre-learning led to a reduction in anxiety. Furthermore, reflecting on their own driving by watching a video after the session significantly reduced anxiety levels and encouraged safer driving behavior.

Verification of 180-degree rotating armrest console rigidity through analysis

Dongmin Kim (KOMOS)

This study focuses on the structural and rigidity verification through various analyses for the development of a 180-degree rotating armrest console among variable console systems. Unlike existing console armrest products, it opens 180-degree, so it must satisfy not only the existing rigidity but also the rigidity when opened. In addition, the safety of the rear seat passengers must be ensured. Therefore, the problems of this 180-degree rotating armrest console are pre-verified and analyzed through analysis.

Measurement of Test Driver Workload in Autonomous Driving
-Effects on Heart Rate and Autonomic Nervous System Indicators During Autonomous and Manual Driving-

Hiroshi Watanabe･Mitsuhiro Takahara (AutoTechnicJapan)･Keiji Jimi (Gunma University)

This study aims to evaluate the workload of test drivers during autonomous driving tests by measuring and comparing heart rate and autonomic nervous system indicators during both autonomous and manual driving. Experiments were conducted at Gunma University, and the results showed that changes in autonomic nervous system indicators were more pronounced during autonomous driving. Additionally, it was confirmed that respiratory activities such as yawning affected heart rate.

Non-Contact Sensing for Real-Time Estimation of Driver Arousal Level During Automated Driving

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

Although automated driving technologies are advancing, the practical implementation of fully autonomous driving still requires time. Therefore, driver monitoring is necessary for the time being, and it is required to assess whether the driver can make appropriate decisions upon resuming manual control. This study aims to construct a real-time non-contact sensing system for the early detection of decreased arousal.

Assessment of human states using heart rate and heartrate variability indices
-Interpretation ofL F/HF index-

Mieko Ohsuga･Yoshiyuki Kamakura (Osaka Institute ofTechnokgy)･Shimpei Yamada･Hiroki Takeuchi (University of Occupational and Environmental Health)

Heartrate and heartrate variability indices, especially LF/HF, which are dimensionless numbers, are frequently used to assess states of drivers and occupants. However, the changes in these indices are complex and subject to misinterpretation due to the effects of inadequate measurement, respiration, speech, and posture and so on. This paper summarizes the considerations in the use of these indices and also discusses the problems of indices obtained from pulse wave data.

Estimation of Chronic Stress Using Pulse Waves and Facial Expression Features while Driving a Car

Masanari Murai･Rio Ishiguro･Kota Toyama (Chiba University)･Daisuke Negishi (Suzuki Motor)･Masato Takahashi･Norimichi Tsumura (Chiba University)

Chronic stress is a major factor that affects both mental and physical health, however its continuous assessment in natural settings remains challenging. This study aims to estimate chronic stress using pulse wave features and facial expressions collected during car driving. We conducted a driving simulator experiment and extracted physiological and facial features, which were then used to train a machine learning model for stress. The stress estimation results achieved a mean absolute error of 3.2. These findings suggest that collecting physiological signals while driving is a viable means of monitoring chronic stress in daily life.

Consideration of appropriate driving supports to achieve successful experiences in alleviating anxiety.

Yosuke Furuya･Yoshihisa Okamoto･Nanae Michida (Mazda)･Norihiro Sadato (Ritsumeikan University)

It is considered what kind of support is appropriate for drivers to achieve successful experiences in alleviating anxiety and transitioning to a positive emotional state through their own actions during high-anxiety driving situations. The effects of driving support, considered effective based on a psychological model, on both emotional and cognitive aspects were verified through experiments using a driving simulator.

Evaluation of Sleepiness by Leg Motion while Driving

Ryotaro Abe･Toshiyuki Shimizu (TS TECH)

This study examined the relationship between driver leg motions and sleepiness. As a result of analyzing the change in body pressure while driving a simulator, it was confirmed that the amount of motion of the left and right leg parts changed according to sleepiness. These results suggest the possibility of evaluating driver’s sleepiness based on changes in body pressure during driving by focusing on leg motions.

Research on Driver Arousal Maintenance Using Vibration Stimulation Based on Heart Rate

Ryuto Takahashi･Shuncong Shen･Toshiya Hirose (Shibaura Institute of Technology)･Kenichi Kamano･Tomoari Aiba･Toshiyuki Shimizu (TS TECH Co.,Ltd.)

In this study, we investigated the effect of vibration based on the driver's heart rate given from the driver's seat to prevent the driver from being hypo-aroused. Experiments were conducted using a driving simulator, and three vibration conditions were presented: 1.1 and 1.0 times of the heart rate, and no vibration. The driver’s arousal time was evaluated by driving maneuvers and facial expressions.. The results indicated that the driver's arousal time significantly extended by the vibration of 1.1 times of the heart rate.

Gear Rattle Noise Analysis Based on Electric Automotive Drivetrain Model

Takeshi Watanabe･Sachio Wada･Tsuyoshi Shinohara･Yoshiyuki Yomogida (SUBARU)

Battery Electric Vehicles (BEVs) are known for their excellent motor response and acceleration．However，gear rattle noise remains a significant challenge．This research provides a detailed model-based analysis of the mechanisms behind gear rattle noise．It indicates the gear rattle behaviors and also presents methods to achieve a high level of balance between vehicle acceleration response and gear rattle noise reduction．

Control Method that Achieves High Acceleration Response and Low Gear Rattle Noise of Electric Vehicles

Yu Takano･Keigo Yamada･Hajime Ishii (SUBARU)

Battery Electric Vehicles (BEVs) are known for their excellent motor response and acceleration. However, gear rattle noise remains a significant challenge. This research provides a control method that achieves a high-dimensional balance between acceleration response and gear rattle noise from mechanisms of the noise.

Auxiliary Brake Apparatus by Air Compression and Release for Stop of Heavy FCV Regenerative Brake (5th Report)
-Two-stage compression system for high brake power-

Chinatsu Sano･Hiroshi Uchida･Toshinori Fujita･Takashi Shibayama (Tokyo Denki University)

A simple structure auxiliary brake by utilizing air compression and release cycle had been proposed in last four reports to prepare for the case of FCV truck regenerative brake failure . In this report, it has been clarified that doubled braking capacity can be achieved without super charge inlet air by adopting two-stage compression system using both end of the compression piston for air compression. The test result will be reported.

Mechanism Analysis of Vehicle Dynamics Using Front-Rear and Left-Right Differential Rotation Constraints for AWD

Kai Kadono･Yusuke Yabusaki･Tomohiro Shimizu･Akira Ono･Satoru Sugiyama･Susumu Ito･Masami Oguri (SUBARU)

This paper investigates the impact on vehicle dynamics caused by the combination of limitations in speed differentials between the left and right, and front and rear wheels of an all-wheel-drive vehicle under snowy conditions. Based on the verification results, the magnitude of the influence of each on vehicle behavior and how to use them differently and cooperate with each other were examined. These combination variants could contribute to optimizing all-wheel-drive control to enhance vehicle stability and steering response on low-friction road surfaces.

Development of the Surrogate Model for Bolt Loosening in Differential Case Ring Gears by Integrating Generative Shape AI and Principles

Kazumasa Watanabe･Tomofumi Shimokawa (Toyota Motor)･Koji Iwayama･Takayuki Onojima (Shiga University)･Hiroaki Tashiro･Hiromasa Ueno･Takahiro Mochihara (Toyota Motor)

We have developed the surrogate model that rapidly predicts bolt loosening in differential case ring gears for design shapes by integrating latent variables and theoretical equations using Generative Shape AI. Furthermore, we report the establishment of the method to generate shapes that meet specified bolt loosening performance criteria.

Numerical prediction of the oil flow accelerated by the momentum received between gear teeth

Yoshihiro Kato･Tadanobu Ueda (Toyota Central RandD Labs.)

In numerically analyzing oil flow stirred by rotating gears, a major challenge lies in predicting the acceleration of oil caused by the reactive forces and the centrifugal forces acting between the gear teeth. To address this issue, we apply the volume of fluid (VOF) method to simulate fluid-gas two-phase flow and calculate the oil flow stirred by a single rotating gear. By comparing the numerical results with velocity measurements, we examine the sources of numerical error and explore ways to improve the prediction technique.

Prevention Design of Electrical Erosion in Deep Groove Ball Bearing for Electric Powertrain（Second Report）

Hideyuki Shiraku･Takahiro Kuwabara･Satoshi Takemoto (Nissan Motor)

Electricity can lead to electrical erosion in bearings due to the electrification of the powertrain. The issue of the electrical erosion is anticipated to be apparent due to high power motor in the future. To implement the optimal design and improve the efficiency of technical development from the beginning of development, we tackled quantitative prevention design for electrical erosion based on the discharge energy.

CAE Prediction of Tire Dynamics with Tread Patterns

Yoichi Mie (Sumitomo Rubber Industries)

Tire patterns significantly influence braking and cornering performance. However, the constantly changing contact patch poses challenges for conventional CAE analysis. To overcome this, we developed a novel dynamic characteristic prediction method for tires using explicit CAE. This method effectively captures the tire's dynamic behavior by representing the continuous changes in contact shape. This presentation will detail the developed method and present results, including contact pressure and stress distributions obtained from the analysis.

Development of a Tire Force Estimation Technique Based on a Four-Wheel Vehicle Model Using the Extended Kalman Filter

SHOTA KITANO･HIDEKI ITOGA･TAKANORI HIBINO･KAZUKI KUWABARA (ToyotaMotorCorporation)

This study aims to achieve high-accuracy virtual sensing of tire forces using an extended Kalman filter with a four-wheel vehicle model. By incorporating suspension K&C characteristics and load transfer due to roll, and applying a Combined Model to the tires, the method achieves estimation accuracy comparable to existing measurement devices.

Improvement of Road Friction Measurement System and Application to Various Road Surfaces

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

We have developed a continuous road friction measurement system based on its contribution to road traffic safety. To improve the reliability of the results and the efficiency of the experiment, we have modified the design of the measurement system, and we present the results of a characteristic measurement experiment on a test course. Next, we conduct μ-s characteristics measurement experiments on various road surfaces with different friction, confirm the accuracy, and propose an analysis method to improve the accuracy.

Development of Visual Analysis Approaches for the Contact Phenomenon Between Tires and Real Road Surfaces

Naohiro Ishigami･Naoki Isayama (Toyo Tire Corporation)

Tire performances are significantly influenced by the contact conditions with the road surface. However, visualizing this contact on uneven asphalt surfaces in real-world scenarios is challenging, leading to the common practice of using flat transparent plates for tire contact evaluation. However, there is a significant difference in contact behavior between flat plates and actual uneven road surfaces. In this study, we developed a method to visualize the contact state of real tires using replica road surfaces that replicate the shape of actual road surfaces with transparent materials. This presentation will introduce the experimental methodology and the results obtained.

Analysis of the influence of motorcycle aerodynamics on frame flexibility

TsuyoshiI I. Katayama･Masanori Myoyo (Kurume Institute of Technology)･Yuto Fujimoto (Kurume Institute Technology)･Takahiko Yoshino (Kurume Institute of Technology)

When the bending freedom of the front frame of a motorcycle becomes softer, the weave mode becomes unstable. Aerodynamic forces affect the amount of bending of the front frame. This paper shows that the aerodynamic forces change the side force of the tire, increasing the amount of bending of the front frame and destabilizing the weave mode.

Distance Calculation and Position Measurement Method Using Omnidirectional Images

Junji Hirasawa (Ibaraki KOSEN, College of Technology)

The author studied a method to estimate the position of a motorcycle using only externally captured image data. In this presentation, a method that utilizes the rider’s helmet as a marker and estimates the distance by incorporating its apparent size in the image is proposed. The results of my preliminary trials using this approach are presented. Furthermore, a method for calculating the vehicle's position and deriving its trajectory by combining these pieces of information is also presented.

Design Requirements Enabling Hands-Free Straight-Line Driving on Slanted Surfaces for a Personal Mobility Vehicle (PMV) Equipped with a Tilting Mechanism
-Comparison with Passenger cars and Motorcycles-

Tetsunori Haraguchi (Nagoya University / Nihon University)･Tetsuya Kaneko (Osaka Sangyo University)

In general, roads are constructed with a transverse gradient relative to the direction of travel to facilitate drainage. For narrow personal mobility vehicles (PMVs), which frequently operate near the left edge of the roadway, it is particularly important to ensure stable straight-line travel without active steering input in order to enhance operational safety. Accordingly, this study aims to clarify the design requirements that enable a PMV equipped with a tilting mechanism to maintain hands-free straight driving on slanted road surfaces, through a comparative analysis with passenger cars and motorcycles.

Investigating the Kinematic Performance of E-scooter via Real-world Comparative Experiment with Bicycle

Huiping Zhou･Akira Ohtani (JARI)･Takashi Hasegawa･Hiroyuki Mae (the Japan Automobile Manufacturers Association)

This study aims to investigate the causes of e-scooter accidents by clarifying the kinematic characteristics. Test-course experiment comparing with bicycle was conducted, and data was collected for straight riding, normal braking, harsh braking, and normal turning scenarios. The results revealed that, compared to bicycles, e-scooter exceeded the designated stopping target line more frequently during normal braking. In harsh braking, a delay of initiating braking and a relatively long stopping distance were observed. Furthermore, e-scooters exhibited less stable speed control in straight riding. These findings suggest that e-scooters' longer stopping distances, especially during harsh braking, may increase the risk of rear-end collisions.

Study on optimization of Two-stage Post Injection under PCCI Combustion

Yoji Hiraiwa･Yukito Watanabe (Hokkaido university, Graduate School of Engineering)･Gen Shibata･Hideyuki Ogawa (Hokkaido university, Research Faculty of Engineering)

Single post injection under the homogeneous in-cylinder conditions generated by PCCI combustion has been shown to be effective in suppressing partial oxidation of the fuel. In this study, Two-stage post injection was introduced under PCCI combustion with the aim of reducing fuel adhesion to the cylinder wall due to weakened spray penetration and efficiently supplying unburned hydrocarbons for DPF regeneration. The optimal DPF regeneration was investigated under PCCI combustion through engine experiments and 3D-CFD analysis.

Effect of the pilot injection on Ignition and Combustion Characteristics of Pentanol in a Common Rail Type Small DI Diesel Engine

Masaki Hirata･Koji Uchida･Hironori Saitoh (sojo University)

This study deals with the development of controlled-ignition technology for high-performance compression-ignition alcohol engines. The objective of this study is to make clear the effect of the pilot injection on the ignition and combustion characteristics of pentanol in a common rail type small DI diesel engine. Experiments were carried out by varying the pilot injection duration and hot EGR ratio under the condition of higher compression ratio (ε=23) in comparison with the original one (ε=18.5). Higher compression ratio was achieved by reducing the volume of combustion chamber formed on the top of the piston.

The Effects of Lower Boiling Point Hydrocarbons in the Diesel Oil on Combustion and Exhaust Gas Emissions Characteristics in a Heavy Duty Diesel Engine

Kunihiro Shimizu･Tomohiro Matsuda･Jin Kusaka (Waseda University)

This study investigates the impact of synthetic fuel properties on improving the combustion and emissions of high-compression-ratio (CR) heavy-duty diesel engines. Diesel, DP2b (Diesel + C6H14: 6:4 vol%), and DP3b (diesel + nC7H16: 6:4 vol%) fuels are tested in a single-cylinder CR=23 engine. Combustion, NOx, and soot are compared under various engine speeds/loads, EGR, and injection timings. A 3D-CFD model was calculated using CHEM-KIVA4 and Waseda’s phenomenological soot model. The results show that DP2b and DP3b generate similar NOx, but soot can be reduced by 25-62% compared to diesel, thanks to the low aromatic content and boiling points.

Effect of fuel ignitability and aromatic components on crystallite size of soot particles from a diesel engine

Yu Kuroshima･Yuki Yamakura･Mizuki Obara (Graduate School of Kitami Institute of Technology)･Kazuki Inaba･Kazuhiro Hayashida (Kitami Institute of Technology)

The effect of fuel ignitability and aromatic contents on the crystallite size of soot particles in a single-cylinder diesel engine were investigated. The influence of cetane number on the crystallite size was minimal for fuels consisting of paraffinic hydrocarbons. Differences were observed in the heat release rate profile during the premixed combustion period between fuels where paraffinic hydrocarbons were blended with diesel fuel and those blended with toluene as an aromatic component, attributable to variations in ignitability. However, the heat release rate profiles during subsequent combustion period showed no significant differences. A reduction in aromatic content led to decreased smoke emissions and a smaller crystallite size in soot particles.

Development of a 1D Combustion Model for Direct Injection Hydrogen Engines Considering Preferential Diffusion

Toshiki Mikami･Hirokazu Kurihara･Yuji Ishii･Kazuhiro Uehara･Hideyuki Handa (Toyota Motor)

This study presents a method for constructing a one-dimensional combustion model for direct injection hydrogen engines using GT-Power. In GT-Power, the equivalence ratio at the flame front is utilized to represent the in-cylinder mixture distribution. In this research, the transition of the equivalence ratio at the flame front is determined by combining calculations from 3D-CFD with actual combustion results from a real engine. Additionally, the parameters for turbulent burning velocity are considered with respect to preferential diffusion. It was confirmed that the constructed model reproduces the combustion characteristics of the real engine well.

Visualizing Hydrogen Jet Concentrations with Negative LIF

Shohei Ishida･Akihiro Ando･Ryusei Tawara (SOKEN)･Shiro Tanno･Jun Miyagawa (Toyota Motor)

Laser-Induced Fluorescence (LIF) is a promising diagnostic technique for measuring the concentration distribution of hydrogen jets with a high signal-to-noise ratio. However, in the case of gaseous fuels, it is difficult to precisely control the vaporization and mixing of the fluorescent tracer, and such fluctuations can adversely affect measurement accuracy. In this study, we applied a background LIF method, in which the tracer is introduced into the ambient environment surrounding the jet, to hydrogen jet flows. By employing image processing, we successfully corrected for variations in tracer concentration, thereby enhancing the reliability of the analysis.

Development of Measurement Method for Equivalence Ratio around the Spark Plug in Spark-Ignition Hydrogen Engine Using M10 Spark Plug

Taisei Bando･Nobuyuki Kawahara･Yoshimitsu Kobashi (Okayama University)･Satoaki Ichi･Kazuki Arima･Hiroshi Kato･Kyohei Izumi (Kawasaki Motors, Ltd.)･Koichiro Matsushita (Honda Motor)･Tomohiko Kamio (Yamaha Motor)･Yoshinari Ninomiya (Suzuki Motor)

The object of this study is to build a SIBS measurement method using an M10 spark plug to measure the equivalence ratio around the spark plug in a Direct-Injection Spark-Ignition Hydrogen Engine. A sapphire window and lateral electrode are attached to the M10 spark plug, and the hydrogen/air mixture ratio is measured using the SIBS method. The equivalence ratio around the spark plug was measured in a Compression-Expansion engine and an actual engine (Engine speed 2000 rpm).

Effect of Excess Air Rate and Injection Timing on Piston Surface Temperature in Cylinder Direct Injection Hydrogen Engines by Temperature Measurement Method Using Multipoint Small Data Logger

Shota Tsukamoto･Masakuni Oikawa･Yuji Mihara･Seiya Yamada･Kentaro Minoda (Tokyo City University)･Masahiko Satou･Toshiyuki Iseki･Junnosuke Yasuda (Komatsu)

One of the challenges of hydrogen engines is the high cooling losses owing to the short flame extinction distance characteristic of hydrogen. In this study, a multipoint small data logger was installed on the piston to measure the temperature distribution on the piston surface, which varied depending on the operating conditions of the direct injection hydrogen engine. As a result, the effects of the air excess rate and injection timing on the piston surface temperature were determined.

Effect of Fuel Supply System on Instantaneous Heat Flux at the Cylinder Liner Wall of Motorcycle Hydrogen Engine

aoshi Yokomori･Masakuni Oikawa･Yuji mihara･Yuki Kaga (Tokyo City University)･Takumi Iwata (MOTORA,Inc.)･Tomohiko kamio･Atsushi Yamamoku (Yamaha Motor)･Kenichi Sano (Honda Motor)･Yoshinari Ninomiya (Suzuki Motor Co., Ltd.)･Michiyasu Owashi (MOTORA,Inc.)

Six instantaneous heat flux sensors were installed in the cylinder liner of a 125cc motorcycle hydrogen engine to determine the effect of the injection method and engine speed on the instantaneous heat flux. As a result, the position of the instantaneous heat flux showing the maximum value differed between the premixing method and the direct injection method, and the tendency for the maximum value of the instantaneous heat flux to increase with higher engine speed was identified.

Comparative Verification of Measured and Numerical Analysis Results in Instantaneous Heat Flux of Motorcycle Hydrogen Engine

Yuki Kaga･Masakuni Oikawa･Yuji Mihara･Aoshi Yokomori (Tokyo City University)･Takumi Iwata (MOTORA,Inc.)･Tomohiko Kamio･Atsushi Yamamoku (Yamaha Motor Co.,Ltd.)･Kenichi Sano (Honda Motor)･Yoshinari Ninomiya (Suzuki Motor Co., Ltd.)･Michiyasu Owashi (MOTORA,Inc.)

Measurements of instantaneous heat flux at the cylinder head of motorcycle hydrogen engine indicated that the behavior of the instantaneous heat flux varied depending on the excess air ratio and measurement position. Therefore, the heat flux values calculated by the numerical analysis were compared with the measured values to understand the causes of the changing heat flux behavior. In addition, the set values of the numerical analysis based on the measured values are discussed.

Development of Elemental Technologies for Hydrogen Engines

Yasuyuki Murata･Hiroki Nagashima･Naoyoshi Nishigata･Ryo Iwashita･Saki Shiratori･Takeru Tagawa･Masato Watanabe (SUBARU)

As the realization of a carbon-neutral society becomes increasingly important, hydrogen fuel is gaining attention as a viable energy source. This study focuses on adapting an existing horizontally opposed engine for hydrogen combustion with minimal hardware modifications. Engine bench testing was conducted to evaluate its performance and durability under hydrogen-fueled conditions. This presentation reports on the reliability challenges identified through the validation process and discusses key considerations for future development of hydrogen engine hardware.

Changes in water content and elements in lubricant due to differences in operating conditions and cylinder wall temperature of a hydrogen engine and their effects on friction and seizure characteristics of engine bearings

Dengda Zhu･Yasuyuki Miyajima･Shinnosuke Higashino (Tokyo City University)･Takumi Iwata (MOTORA, Inc.)･Masakuni Oikawa (Tokyo City University)･Yusuke Iizuka･Rikuto Saito･Ko Onodera (ENEOS Corporation)･Yuji Mihara (Tokyo City University)

Water vapor generated by hydrogen combustion tends to condense on engine walls at low temperatures, leading to the emulsification of lubricant and the degradation of its lubrication performance. In this study, a single-cylinder hydrogen engine was operated for 33 hours to evaluate the lubricant’s emulsification behavior. Furthermore, the scuffing characteristics of fresh, emulsified, and dehydrated lubricants were compared using a bearing test rig, with a focus on the effects of lubricant additives.

Effects of changes in water content of lubricant oil due to combustion in hydrogen engines on friction characteristics of piston systems.

Shinnosuke Higashino･Yasuyuki Miyajima･Dengda Zhu (Tokyo City University)･Takumi Iwata (MOTORA, Inc.)･Masakuni Oikawa (Tokyo City University)･Yusuke Iizuka･Rikuto Saito･Ko Onodera (ENEOS Corporation)･Yuji Mihara (Tokyo City University)

In hydrogen internal combustion engines, the mixing and emulsification of water produced by hydrogen combustion into the lubricant is an issue.
In this study, therefore, we used a floating liner engine to evaluate the physical properties of lubricant oils containing a specific percentage of water , and also measured and evaluated the friction characteristics of these lubricants under fixed conditions. We also performed an evaluation using lubricant after evaporating the mixed water.

Avoidance behavior when encountering dangerous driving by others and driving behavior aimed at ensuring physical margin during city driving by human drivers. (the 1st report)

Toru Kojima･Yuki Manabe･Koichi Kitada･Kenji Morizaki (NALTEC)

Assuming automated vehicles will share general roads with human drivers, we used a driving simulator to investigate normative driving behaviors for automated vehicles, including harmony with surrounding traffic. Specifically, we examined the Avoidance behavior when encountering dangerous driving by others and driving behavior aimed at ensuring physical margin during city driving by human drivers, including violations of traffic laws.

Avoidance behavior when encountering dangerous driving by others and driving behavior aimed at ensuring physical margin during city driving by human drivers. (the 2nd report)

Yuki MANABE･Toru KOJIMA･Koichi KITADA･Kenji MORIZAKI (NALTEC)

Assuming automated vehicles will share general roads with human drivers, we used a driving simulator to investigate normative driving behaviors for automated vehicles, including harmony with surrounding traffic. Specifically, we examined the Avoidance behavior when encountering dangerous driving by others and driving behavior aimed at ensuring physical margin during city driving by human drivers, including violations of traffic laws.

Analysis of physical and gaze behavior factors influencing driver responses in intersection collisions

Kotaro Sugiura･Yuki Nitta･Yuqing Zhao･Koji Mizuno (Nagoya University)

This study aims to identify the factors influencing drivers’ braking reaction time (BRT) in car-to-cyclist collisions at intersections. By using results from driving aptitude tests and visual behavior data obtained from driving simulator experiments as explanatory variables in a decision tree model, the results show that scan frequency is the most influential factor affecting BRT, followed by dynamic visual acuity.

Gaze behavior analysis using a driving simulator

Yuki Nitta･Kotaro Sugiura･Yuqing Zhao･Koji Mizuno (Nagoya University)

Car-to-cyclist collisions at intersections occur frequently, and it is important to clarify the contributing factors. Moreover, many of these accidents have been found to occur under low-visibility conditions caused by inclement weather. In this study, a driving simulator was used to reconstruct various driving environments, including clear, nighttime, and rainy conditions. Driving behavior and visual data were analyzed to investigate differences in drivers’ emergency responses. The experimental results revealed that drivers’ gaze behavior varied depending on the driving environment, which contributed to differences in their responses to cyclists.

A Study on the Effects of Differences in Driver’s Brain Activity on Curve Recognition and Driving Performance

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

This study focused on the driver's brain activity in the prediction section, which is the stage before recognition, and analyzed the effects of superior or inferior brain activity on recognition and driving performance on curved roads from experiments using a driving simulator. The results showed that when the frontal lobe was activated in the predictive section, the recognition of curve became faster and the amount of lane departure in the curve section was decreased.

A Study on Optimal Driver Posture with Low Driving Burden
-Impact on Hazard Avoidance Scenarios-

Naoya Yamakawa･Souma Adachi･Ryoto Warashina (Suwa University of Science)･Masashi Makita (Teikyo University)･Hiroshi Kuniyuki (Suwa University of Science)

In this study, a hazard avoidance scene was set up using a driving simulator and the effects of seating posture on muscle strain and hazard avoidance performance were analyzed. The results showed that in braking avoidance, the forward lean posture had higher avoidance performance but also higher muscle burden, while in steering avoidance, the standard posture with a natural elbow joint angle had lower muscle burden and higher avoidance performance.

Impact of Roadside Sensor’s Sensing Performance on Automated Driving at Intersections Using Cooperative Systems

Hiroshi Yoshitake･Jiang Wu (Institute of Science Tokyo)･Wataru Kugimiya (The University of Tokyo)･Motoki Shino (Institute of Science Tokyo)

To realize safe and efficient automated driving in mixed traffic environments, our previous study demonstrated the effectiveness of cooperative systems utilizing roadside sensors. In this study, we hypothesize that the sensing performance of roadside sensors—such as detection rate and accuracy—can significantly affect the safety and efficiency of automated driving. To examine this impact, we conducted numerical simulations focusing on an automated bus traveling through an intersection.

Extraction of Contributing Factors for Safe Speed Calculation of Automated Buses Traveling Straight Through Intersections

Taichi Sawanobori･Hiroshi Yoshitake (Institute of Science Tokyo)･Yui Matsuura･Masaya Segawa (Advanced Smart Mobility)･Motoki Shino (Institute of Science Tokyo)

Currently, the speed of automated buses is subjectively determined based on the driver’s experience. However, for social implementation, a logical basis for speed setting is required. This study focuses on the difference between the safe speed that allows for collision avoidance with anticipated road users and the actual set speed. We identified the factors that should be considered when driving straight through intersections and examined a method for calculating safe speed that accounts for these factors.

Development of ultrasonic transmission simulation to predict the effect of sonar false detection

Motoyasu Ukai･Takaaki Nakamura (Aisin)

High-precision sensing technology is essential to realize autonomous driving and autonomous parking. AEB (Automatic Emergency Braking System) detects obstacles using ultrasonic sonar, but false detections occur due to the influence of surrounding vehicle parts. In this study, we report on our efforts to develop CAE technology that can predict sensor signals when installed in a vehicle and judge whether they are good or bad.

Effects of Cooperative Assistance Systems on Pedestrians by Using Mixed Reality

Yuki Sakamura･Ryohei Homma･Takashi Wakasugi･Genya Abe (JARI)･Motoki Shino･Hiroshi Yoshitake (Institute of Science Tokyo)･Yuji Takagi (Honda R&D)･Takashi Misumi･Tadafumi Shima (MLIT)

We investigated the effects of cooperative assistance using networks on pedestrians crossing roads in avoiding accidents, and the minimum timing of assistance notification that should be satisfied. An experiment using mixed reality technology were conducted on two actual cases in which pedestrian accidents have been occurring frequently in Japan. The effectiveness rate of the assistance was confirmed from the experiment data, and appropriate assistance timing was examined.

Camera Exposure Time for Reproducing Human Perceived Visibility in Snowstorms

Toshimitsu Sakurai･Hirotaka Takechi･Ikku Koshikuni･Masaru Matsuzawa (Civil Engineering Research Institute for Cold Region, PWRI)

Road administrators refer to CCTV camera footage to assess snowstorm conditions on-site and determine whether to dispatch road patrols or snow removal operations. However, since human vision and CCTV camera capabilities differ, the snowstorm conditions captured by cameras do not always correspond to the visibility experienced by individuals. This study aims to reproduce human-perceived snowstorm conditions using cameras. The results indicate that setting the camera’s exposure time to approximately 15 milliseconds enables recognition of visibility comparable to human perception. Furthermore, reducing the exposure time enhances long-distance visibility even in severe weather conditions, such as snowstorms.

2D quantitative measurement of friction coefficient μ with icy road surface using a NIR camera

Tomoki Kawahara･Akihiro Kido (Tohoku Gakuin University)

There are many technical challenges in measuring the slipperiness of roads in snowy and cold regions, and it is currently limited to qualitative measurement. In this study, we focused on the fact that ice has an absorption band in the near-infrared range, and attempted non-contact quantitative measurement using a near-infrared camera. As a result, two-dimensional quantitative measurement of the friction coefficient μ became possible by the processing the captured images.

Relationship between Void Distribution Function of Soft Polyurethane Foam and Mechanical Property (Compression Force - Displacement Characteristic) (First Report)
-Development of Evaluation Methodology and Parameter Studies of Void Distribution Function-

MINORU INOUE (Mazda / Kagawa Univ. / Hiroshima Univ.)･KEISUKE SUZUKI (Kagawa University)･HIROYUKI ITO (TOYO SEAT Co.Ltd.)

Mechanical properties (compression force – displacement characteristics) of the soft urethane foams used for seats have a great impact on vehicle ride comfort performance. However mechanical properties are resultantly determined by the base plastic material, chemical blowing agents and molding conditions and so controlling and designing mechanical properties in advance are difficult. Because of the recent developments of measurement and image processing techniques, void distribution function of the urethane foam can be obtained and methodology to evaluate the mechanical properties using void distribution functions are established and applied to the urethane parameter studies.

Study on Damping Performance of Resin and Metal Members with Bolted Joints
-Mechanical Factors of Vibration Damping and Analysis Model-

Keisuke Inoue･Tristan Samuel Britton (Fujimori)･Yoshinao Kishimoto･Yukiyoshi Kobayashi･Satoru Kuga･Yuuki Kawaharabashi (Tokyo City University)

Resin materials such as ABS resin are used in interior and exterior parts of automobiles to ensure vibration absorption and impact resistance. In this study, hammering tests were conducted to clarify the main factors that determine damping performance of structures with bolted jointed resin and metal members. It clarified the factors are viscosity of the resin and friction between the members, and the finite element analysis was used to predict the damping performance.

Development of Body Part Integration Technology Utilizing Ultra High Strength Steel and Cold Stamping

Ryo Ageba･Shunsuke Tobita･Satoshi Sumikawa･Yoichiro Onishi･Kazuhiko Higai･Tsuyoshi Shiozaki (JFE steel)

To reduce manufacturing costs in vehicle bodies, aluminum casting and hot stamping technologies are gaining attention. Simultaneously, cost reduction through component integration is being explored for cold-pressed parts. This report focuses on the rear member structure, proposing a reduced component design that balances crash performance, rigidity, and formability by utilizing ultra high-strength materials and cold pressing techniques.

Examination of analytical conditions for VOC components in vehicle interior using hydrogen carrier gas TD-GC-MS

kyosuke Karaki･Koichi Tatsu (Isuzu Motors)･Kunihiro Hoshino (ENV Sciences Trading)･Sadao Nakamura･takeshi Serino (Agilent Technologies Japan)･maiko Tahara (National Institute of Health Sciences)･Matsui Hidechika (Tokai Technology Center)

Quantitative analysis of VOC components was performed using TD-GCMS with hydrogen carrier gas. Sensitivity and LOQ were confirmed, and quantitative analysis was compared with that using helium carrier gas to determine optimal analytical conditions.

Development of a brake chamber failure prediction model using machine learning

MIKIYA OKUZAWA･Tomoya Suzuki (Ibaraki University)

Brake chambers used in transport trucks are the most important parts in terms of safety. However, they are prone to deterioration due to internal corrosion caused by rust, which makes visual inspection difficult. Therefore, by using machine learning to learn about the operating conditions of trucks, we aim to develop a predictive model that estimates the risk of brake chamber failure and use it as a criterion for deciding whether to perform expensive disassembly and inspection.

Development of prediction method for SPR(Self Piercing Rivet) joint strength using machine learning

Kento Shimizu･Yuta Suzuki･Hirotaka Sakamoto･Toshiyuki Isono･Kohei Takahashi (Toyota Motor)･Narihisa Fujimoto (TOYOTA MOTOR KYUSHU)

SPR (Self Piercing Rivet) joint is enabled to join dissimilar materials, but it is difficult to predict fatigue strength without testing and detailed mesh simulation because, it varies from plate combination. Therefore, it is essential to develop a method to predict fatigue strength of SPR easily. This report describes the investigation of SPR joint fatigue strength prediction method using a machine learning model with random forests, based on specimen test result.

High-resolution topology optimization of instrument panel beams

Yuji Wada (Institute of Science Tokyo)･Takeshi Kashiyama･Kei Nagasaka (Suzuki Motor)･Koji Nishiguchi (Nagoya University, RIKEN)･Shigenobu Okazawa (University of Yamanashi)･Makoto Tsubokura (Kobe University, RIKEN)

The instrument panel beam at the front of the vehicle body is often made of hollow tubes, but in order to reduce the number of parts, one-piece molding has been considered in recent years. Voxel topology optimization is performed under the CUBE framework and the resulting optimal shape is compared with existing parts to study stiffness performance and manufacturability using a plate manufacturing constraint.

Machine learning surrogate models for real-time Tire contact Finite Element Analysis

Akira Wada･Ryoji Sekine (TOYO TIRE)

Potential fundamental characteristics of tires are analyzed by tire contact finite element analysis. It is necessary to find the optimal design values efficiently, however they have hundreds of design variables. In this paper particularly focuses on tire profile variables and presents cases where a surrogate model enabling real-time simulation and evaluated for predictive accuracy within a certain design space.

A Study on Enhancing the Accuracy of Crash CAE Predictions for Fiber-Reinforced Plastic Components through the Utilization of Surrogate Models

Yoshikazu Nakagawa･Osamu Ito (Honda Motor)

To rapidly predict the fiber orientation of resin parts, essential for automotive crash analysis, we developed a surrogate model by extending the machine learning algorithm pix2pix to 3D. A comparison with resin flow analysis results confirmed the model's high accuracy. This approach successfully reduces the substantial workload associated with the entire labor-intensive flow analysis process.

Shape Optimization of Aluminum Extrusion Considering Manufacturing Constraints

Yuto Komatsu･Shota Chinzei･Taiki Yamakawa･Narikazu Hashimoto (Kobe Steel)

Aluminum extrusion design offers significant flexibility due to variations in cross-sectional geometry and internal rib configurations. However, achieving a globally optimal design is challenging through manual methods. While shape optimization is increasingly applied, it often overlooks manufacturing feasibility. This study presents and validates a technology that incorporates manufacturing constraints of extrusion process into the AI-driven shape optimization of aluminum extrusions.

3D Shape Generative AI for Thin Sheet Metal Components under Geometric Boundary Shape Constraints

Takumi Sugiura (JSOL)･Isamu Hashiguchi (The University of Osaka)･Atsushi Takahashi･Nobuhiro Taki (JSOL)･Koji Nishiguchi (Nagoya University)･Kei Saito (JSOL)

This paper proposes a 3D shape generative AI method to enhance efficiency during the early structural design phase of vehicle development. For sheet metal components, the method is capable of generating multiple internal shape concepts under specified geometric boundary shape constraints. The hood is used to demonstrate the proposed method.

Tread Pattern Design Technology that Balances Functionality and Aesthetics Using Generative AI

Ryoichi Ishihara･Shuichi Karatsu (TOYO TIRE)

The tread pattern must satisfy not only physical performance criteria, such as ride comfort and low fuel consumption, but also aesthetic design requirements. In this study, we propose a framework for optimizing tread pattern designs that simultaneously balance physical performance and aesthetics. We utilized CAE to evaluate physical properties and applied AI models for generating tread patterns and assessing aesthetic qualities.

Development of Real-World-Emission Reduction Technologies (First Report)
-Establishment of a Digital Twin Development Environment-

Masato ikemoto･Kentaro Mineo･Mie Kato･Takahiro Tsukagoshi･Hiromasa Nishioka･Bungo Kawaguchi (Toyota Motor)･Yuki Moribe･Masayasu Harimoto (Toyota Technical Development)

In addition to modal emissions, measures to address local emissions in the real world are being considered. Since traffic flow and driving characteristics influence real world emissions, a highly reproducible evaluation environment is necessary. By establishing a digital twin development environment that integrates traffic flow simulation, driving simulators, and vehicle simulators, it has become possible to evaluate emissions equivalent to those on actual roads.

Development of Real-World-Emission Reduction Technologies(Second Report)
-Consideration of Real-World-Emission Reduction-

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

In the real world, emissions are released locally based on the combination of traffic flow, driver behavior, and the condition of the catalyst. By utilizing miniPEMS, we analyzed the emission points and mechanisms of real-world-emissions. Additionally, we employed a digital twin environment to examine the control of the exhaust system, including the catalyst and air-fuel ratio, and to verify the robustness of countermeasures under various traffic flow conditions.

Development of Powertrain Technologies for Achieving Zero Emissions (Part 1)
-Improvement of the Trade-off Between Purification and Pressure Loss in Catalytic Reactions-

Hiroyoshi Ueda･Hiromu Sasaki･Kazuhiro Umemoto･Hiromasa Nishioka･Bungo Kawaguchi (Toyota Motor)

In the development of environmentally friendly vehicles aimed at achieving carbon neutrality, reducing air pollutants remains a critical challenge. Conventional approaches to improving exhaust purification efficiency often involve trade-offs, such as increasing catalyst volume or cell density, which result in higher pressure loss. This study investigates the fluid dynamics near the catalyst cell inlet, focusing on enhancing gas–catalyst interaction through the use of convection. By leveraging this mechanism, we have developed an innovative structural design that improves purification performance while improving the traditional trade-off with pressure loss.

A study on Screening method for Catalysts Using Arc-plasma Deposition

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

To address urban air pollution and global environmental issues, the development of technologies to neutralize or recycle various exhaust gas components is crucial. This report introduces a screening method to efficiently explore conditions and catalysts suitable for these reactions.

Prediction of exhaust gas purification performance of Pd/CZ-based three-way catalysts for plug-in hybrid passenger vehicles

Yuma Endo･Jin Kusaka (Waseda University Graduate School)･Yuya Hato･Takashi Araki (Mazda)

A numerical model was constructed to predict the purification performance of three-way catalysts for plug-in hybrid vehicles. Pd/CZ catalysts with accelerated degradation equivalent to 65,000 km usage were used to conduct CO pulse adsorption tests and light-off tests in lean, stoichiometric, and rich atmospheres in a mini-reactor. The results showed that the calculation model was able to approximately reproduce the purification behaviors of CO, C3H6, and NO at 150-400 °C.

Smoke emission characteristics of biofuels

Kenichi Tomomatsu･Masaharu Ito (SOKEN)･Yo Usui･Takashi Kawachi･Gaku Kishimoto (Toyota Industries Corporation)

As the transition toward carbon neutrality accelerates, the drop-in adoption of biofuels as alternatives to diesel fuel is progressing. However, due to regional characteristics and regulatory differences, various fuels are expected to be distributed. This study aims to predict smoke emissions based on the fuel properties and spray characteristics of biofuels, thereby contributing to the development of engine calibration for various biofuels in the market.

Development of Pipeline Design Method using 3D Shape Generation via Integration of Variational Autencoder and CAD

Shoichiro Kisanuki･Naoya Matsumura･Takuya Sugiura (AISIN)

Surrogate models have been used to accelerate performance evaluation of thermal-fluid products such as heat sinks. While these models enable rapid evaluation, creating 3D models remains time-consuming. This study presents an approach integrating VAE with CAD to generate 3D models efficiently. The proposed method reduces modeling time and supports design exploration.

Numerical Simulation of flows around DrivAer models using the Cartesian Cut-Cell Method

Kazuyuki Ueno･Atsumi Furusawa･Yuki Takeda･Masayuki Juryozawa (Iwate University)

A numerical simulation code based on the Cartesian cut-cell method was developed and simulations of the airflow around automobile modes were conducted. The vehicle geometries used in the simulations are the DrivAer models, developed as benchmark geometries by the Technical University of Munich, Audi AG, and BMW AG.
Numerical simulations of the DrivAer Fastback model during straight driving were performed, and it was confirmed that the pressure coefficient distribution and drag coefficient are in general agreement with a past experiment.
In addition, numerical simulations of the DrivAer Notchback and the DrivAer Estateback models in the presence of crosswind were performed, showing that the DrivAer Notchback model has a larger drag increase with increasing yaw angle.

Analysis of cabin odor components to improve vehicle interior air quality (VIAQ)

Miwako Oro･Mie Hirahara･Yuki Koda (Mazda)

In this study, we present the analysis and evaluation of cabin air components, with a particular focus on human-derived elements, aimed at improving cabin air quality. Through qualitative and quantitative analysis of the components present in the cabin air, we converted these findings into odor intensity parameters, which indicate the impact on humans, and identified the odors and their sources. Furthermore, we compared the results of sensory evaluations with the analytical results to discuss the validity of the evaluation methods.

Study of the Far Side Occupant Behavior in Side Impact in the Case that the Occupants seated in Driver and Front Passenger Seats

Yoshinori Tanaka･Yashiro Matsui･Naruyuki Hosokawa･Masatoshi Usui (National Agency for Automobile and Land Transport Technorogy Natrional Trarfic Safety and Environment Laboratory)

We conducted the side impact experiments under the condition that the dummies were seated on driver and passenger seats in accordance with UNR95 test procedure.
As a result, in a kei-car, the heads of the occupants impacted with each other, and the HPC exceeded the threshold. In a small passenger vehicle, the head of the far-side dummy impacted with the shoulder of the near-side dummy.

Latest Technique in Airbag Folding Model

Rie Kodama･Akifumi Daidoh･Chiharu Murase･Kazuo Imura (Toyota Motor)

Recently, Virtual Testing (VT) has been introduced in automotive crash safety assessment. Car manufactures must have confidence that CAE model predicts occupant response in VT various load cases. Airbag model folding is a key factor for occupant restraint simulation, however, creating the folding model is technically complex and time consuming in the VT process. In this study, the factors consuming a significant amount of time in the creation of folding model was identified, and techniques to improve them were developed. As a result, a folding method was established in approximately 40% of the time compared to the conventional methods.

Evaluation of the Effects of Restraint Conditions on Pelvic Kinematics of Rear Seat Occupants in Frontal Impact

Toshiharu Azuma･Yuqing Zhao･Koji Mizuno (Nagoya University)･Kei Nagasaka･Takahiro Suzuki･Idemitsu Masuda (Suzuki Motor)

FE simulations reproducing frontal impact sled tests were conducted using crash test dummies (THOR, Hybrid III) and human body models (THUMS) in rear seats. An L18 orthogonal array was used to evaluate the effects of seatbelt anchor position, the presence of restraint devices, and seat pan angle on pelvic rearward rotation and forward displacement.

Generation of Vehicle Body Deformation Data for Occupant Lower Extremity Injury Prediction in Crash using Machine Learning

Kyohei Noguchi (University of Yamanashi)･Kei Nagasaka･Idemitsu Masuda (Suzuki Motor)･Yuta Yokoyama (Diver Technology Corporation)･Hirofumi Sugiyama (University of Yamanashi)･Shigenobu Okazawa (University of Yamanashi/Diver Technology Corporation)

To develop a machine learning model for predicting lower extremity injuries of occupants based on dashboard deformation behavior during a crash, time-series data of various dashboard deformations are required as input for numerical analysis. As a preliminary step, we predict the time-series deformation of simplified structural components. Numerical experiments are conducted to investigate the effects of different input factor combinations and data structures. Finally, the performance of the proposed models is evaluated.

Safety performance evaluation of transport wheelchairs with simplified locking systems using sled test

Keisuke Fukuyama･Yoshihiro Sukegawa (JARI)･Yuuya Ueda (JAMA)

In Japan, the number of wheelchair users is expected to increase further due to the aging population. For this reason, there is a need for the standardization of simple and reliable wheelchair locking systems in vehicles and the dissemination of transport wheelchairs . In this report, we evaluate transport wheelchairs equipped with simplified locking systems using the sled tests in accordance with ISO standards, and discuss the required strength performance.

Damage assessment of pedestrians collided by high-velocity runaway vehicles
-Risk assessment between high-velocity runaway vehicle and pedestrian collision from statistical accident data analysis-

Yasufumi Sekine (Fukuyama University)

In collisions between high-velocity runaway vehicles and pedestrians, the velocity at which the accident occurs is an important factor that determines the extent of damage, such as injury degree of pedestrians. In this study, the author analyzed the relationship between vehicle velocity and fatal or serious rate of pedestrians from traffic accident statistical data analysis and examined to clarify the aggressiveness of high-velocity runaway vehicles toward pedestrians.

Rider Kinematics and Head Injury Evaluation in Full-Scale Car-to-Electric Scooter Crash Tests

Akihiro Kido･Takaaki Terashima･Ryunosuke Sakamoto･Kenshiro Kato (National Research Institute of Police Science)･Ryo Oga (Japan Safe Driving Center)

Our previous study revealed that electric scooter riders are at high risk of head injury in traffic accidents. In this study, we conducted full-scale crash tests in which a car collided with an electric scooter ridden by a crash test dummy. The rider’s kinematics, as well as the mechanism and severity of the resulting head injuries, were analyzed.

Effect of riding height of electric scooter on flying behavior of small-sized human body when colliding with a bonnet vehicle

Ryo Oga (Japan Safe Driving Center)

In this study, we study the form of encounter accidents in which a bonnet vehicle collides with the side of an electric scooter. The riding position of an electric kick scooter is not the sitting position of a bicycle, but is closer to the standing position of a pedestrian. Therefore, we compared the post-crash behavior of pedestrians and electric scooter riders. As a result, we found that standing on the step of an electric kick scooter affects the flying behavior of the human body. However, the subject is limited to the Hybrid-III AF05 equivalent, which reproduces a small physique.

Development of a Flexible Head Protection Cap for Cyclists (Concept Model)

Atsuhiro Konosu (JARI)

Since the shape of the current bicycle head protector does not change along the head, it causes discomfort when wearing it and low storability, which is one of the factors that reduces the wearing rate. Therefore, we initiated to develop a bicycle head protection cap that has both flexibility and head protection properties. This paper introduces a concept model of it.

Proposed Impact Performance Design Method Intended for Multi-Performance Optimization Based on Energy Propagation
-Design for S-Shaped Thin-Walled Member-

Xin Yuan (Kanagawa University Graduate School of Engineering)･Toru Yamazaki･Kai Kurihara (Kanagawa University)

The Impact Statistical Energy Analysis (ISEA) is a method for evaluating impact performance based on energy propagation. In this study, the front-side-member of an automobile is modeled as a S-shaped thin-walled member, and a design method using ISEA is proposed. The designed member is validated through FEM analysis, demonstrating the effectiveness and practicality of the design using ISEA.

Prediction of strain distribution in press forming using machine learning

Mayu Nitta (University of Yamanashi)･Okumoto Yuki･Kosuke Kojima (Mazda)･Genbu Takahashi (University of Yamanashi)･Yuta Yokoyama (Diver Technology Corporation)･Hirofumi Sugiyama (University of Yamanashi)･Shigenobu Okazawa (University of Yamanashi/ Diver Technology Corporation)

Accurate prediction of residual deformation and strain caused by press forming is essential for precise estimation of crash energy absorption. However, performing numerical simulations for each case is computationally intensive. To address this issue, this study proposes a machine learning-based approach to estimate residual strain distribution. The selection of training data and input features is carefully examined to enhance prediction accuracy. The proposed method is validated through numerical examples of effectiveness.

Multi-step Shape Optimization Method using Isogeometric Analysis（Second Report）
-Robust Search Independent of Initial Shape-

Mizuki Hoshino (University of Yamanashi)･Shinichi Arimoto･Kosho Kawahara (Toyota Motor)･Yuta Yokoyama･Hirofumi Sugiyama･Shigenobu Okazawa (University of Yamanashi)

To achieve global shape optimization using Isogeometric Analysis, we develop a scheme that automatically repeats optimization and changes the number of control points. In this report, we compare the derived shapes from different initial shapes and expand the search range to realize a more robust shape optimization that is independent of the initial shape.

FRP crash box made from a composite of carbon and flax fiber
-(Experimental consideration on impact absorption performance)-

Naoya Matsumoto･Hijiri Otake･Shinobu Kasamatsu･Wenbao Wu･Ikkei Kobayashi･Junpei Kuroda･Hideaki Kato･Takayoshi Narita (Tokai University)

Carbon fiber-reinforced plastics are used in many industrial products, but because of their high heat resistance, recycling processes have not yet been fully established and there is a need to reduce the use of these materials. Therefore, we focused on flax fiber-reinforced plastics and conducted an experimental study of their shock-absorbing performance by preparing specimens made of carbon fiber and flax fiber composites and conducting drop-weight experiments.

Development and Practical Application of an Analysis Process Utilizing Surrogate AI

KAZUTO UEHARA (AISIN)

In the fluid analysis of an electric water pump, the introduction of surrogate AI on the upstream side reduced the number of CAE computations and improved the efficiency of the analysis process. This report presents the practical application and effectiveness of AI technology in the analysis process, including case studies aimed at improving prediction accuracy.

AI-Driven Vehicle Cyber Risk Modeling for Comprehensive Cybersecurity Management Systems

Eugene Shubov (CTO)

In response to the increasing threats and complexity of vehicle architecture, we introduce an AI-driven approach for continuous vulnerability and threat monitoring and risk assessment. This approach utilizes AI to automate the construction of cyber risk models based on the vehicle architecture. Additionally, it facilitates CSMS compliance by optimally defining mandatory controls, cybersecurity tests, and IDS detection use cases. Furthermore, it helps in assessing vulnerabilities to ensure homologation approval for SUMS in accordance with UNR 155/156 and GB 44495/44496.

Improvement of End-of-Life Vehicle Chassis Number Reading Software Using AI-OCR

Masayoshi Nakamura (National Institute of Technology (KOSEN), Akashi College)･Shigeya Ikebo (Nagoya Bunri Univ.)･Satoru Yaseda･Hitoshi Yamasaki (Aratani Shoukai)

In order to comply with the resource recovery incentive system scheduled to be implemented from 2026, we developed VIN number reading software using AI-OCR two years ago. When the VIN numbers of 1,000 vehicles were read using the software, the reading accuracy was 64%. In this research, we worked to improve the reading accuracy of the software and have achieved some results, so we report here.

Study on Predicting Conductive Emissions in Electric Vehicles During Charging Utilizing Both EMC Simulations and Neural Networks

Makoto Jomoto･Keishi Miwa･Naoya Kajiura (Toyota Motor)

The requirements for vehicle certification include measuring conductive emissions generated by vehicles in the rechargeable energy storage system (REESS) charging model when coupled to the power grid through its AC or DC power lines. Recently, simulations and neural networks for predicting EMC performance have gained attention as a means to reduce the time and cost required for performance verification. In this paper, we aim to utilize both EMC simulations and neural networks to predict conductive emissions.

Stress Level Analysis Due to Differences in Application Methods in Electrostatic Discharge Testing

Hiroki Itozakura (Toyota Motor)･Takeshi Ishida (NOISE LABORATORY)

In electrostatic discharge testing, there are three application methods: contact discharge, air discharge and gap discharge, and the stress level changes depending on the application method. Additionally, in the case of air discharge, the stress level can also change due to differences in approach speed and humidity. This paper compared and analyzed the differences in stress level caused by application methods and environmental factors from the perspectives of peak current, rise time and frequency components.

A study on the effects of HEMP for automotive equipment

Akira Mori (Toyota Motor)

With the advancements in CASE, concerns have arisen regarding the effects of HEMP (High-altitude Electro-Magnetic Pulse) for automotive equipment. We conducted a study on this issue. We applied HEMP pulses (50 kV/m) to test samples that simulated vehicle wire harnesses and measured the induced voltage waveforms. As a result, we confirmed that the test samples induced voltage waveforms similar to those caused by electrostatic discharge.

Construction of direct evaluation system of adsorption/desorption speed for physisorption of carbon dioxide

Yoshitaka Hirabayashi･Takashi Kuraishi･Hiroshi Yokoyama (Toyohashi University of Technology)

To establish technologies for the separation and recovery of carbon dioxide in exhausted gases from plants and transport vehicles, the system for direct measurements of adsorption/desorption speeds in the physical adsorption of carbon dioxide with a plate-type adsorbent was constructed. Moreover, the effects of acoustic excitation to the adsorbent, which is known to affect the adsorption, on adsorption/desorption are investigated using this system.

Effect of heating conditions on evaluation of fiber orientation in carbon fiber-reinforced polymer composites using halogen spot periodic heating

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

Recently, carbon fiber-reinforced polymer composites have attracted interest in the automotive industry. These composites exhibit higher strength in the longitudinal direction than in the transverse direction of the fibers, making their fiber orientation evaluation crucial. In this study, we investigate the effect of heating conditions on evaluation of fiber orientation in carbon fiber-reinforced polymer composites using halogen spot periodic heating.

Effect of Fire-Resistant Structural Design on the Mechanical Properties of Fiber-Reinforced Polymer Composites

Yusuke Ishihara･Asami Nakai･Masayuki Okoshi (Gifu University)･Atsushi Yuki･Satoshi Enokida･Kouhei Kajitani (DaikyoNishikawa)･Shuhei Yasuda･Junichi Ogawa･Yuki Yamada (Mazda)･Masahiko Shigetsu (Hiroshima University)

The use of electric components in automobiles has led to a demand for improved fire resistance of FRTPs. The objective of this study is to establish a fire resistant structure that can achieve both sufficient flammability and mechanical properties by surface treatment. FRTP moldings with fire resistance were prepared by surface treatment, and the effects on flammability and mechanical properties were evaluated by combustion tests and mechanical tests, respectively.

Design and Performance Evaluation of CFRP Pipes Aimed at High Energy Absorption Characteristics

Riki Oishi･Kakeru Aoike･Asami Nakai (Gifu University)

From the perspective of lightweight design, CFRP pipes with braided structures have attracted considerable attention as energy-absorbing components in automotive applications. This study focuses on hybrid braided structures, employing multiple types of fiber bundles, and aims to design and evaluate CFRP pipes that achieve high energy absorption without compromising their mechanical properties.

Development and Validation of a Finite Element Model for Predicting the Bending Characteristics of CFRP Hat-Shaped Components

Masaharu Noguchi (SUBARU)

To expand the application of CFRP for automotive lightweighting, we are developing reliable analysis techniques. We conducted basic material tests and three-point bending tests on CFRP hat-shaped components, and constructed a finite element model based on the obtained mechanical properties. The validity of the model was verified by comparing the simulation results with experimental data.

Study on Vibration Characteristics of CFRP Plate Bolted Member

Satoru Kuga･Yuuki Kawaharabashi･Yoshinao Kishimoto･Yukiyoshi Kobayashi･Keisuke Inoue･Tristan Samuel Britton (Fujimori) (Tokyo City University)

Carbon fiber reinforced plastic (CFRP) is used as a structural material for car bodies due to its light weight, high strength, and high rigidity. However, there are few studies on the vibration characteristics of structures in which CFRP is bolted jointed, and this issue is an obstacle in product development. In this study, impact tests were conducted on bolted CFRP members to investigate the factors that affect stiffness and damping performance.

Evaluation method of dynamic interlaminar shear strength of CFRP for higher accuracy.

Ryohei Miyake･Kazuya Miyata･Masateru Yoshizumi･Hiroyuki Ogata (JFE Techno-Research)

The double-notch compression method is preferred for evaluating interlaminar shear strength of CFRP, but the strength might be overestimated due to friction between the fixture and specimen in the case of high-speed deformation. The tensile method is not affected by frictional forces, but it usually have greater out-of-plane deformation than the compression method, resulting in keeping the deformation mechanism away from pure shear. In this work, the digital image correlation method was used to modify the geometry of the tensile specimen to deform as closer to pure shear, thereby improving the accuracy of the dynamic interlaminar shear strength evaluation method.

Crack propagation simulation for lap joints considering adhesion

Hirofumi Sugiyama･Shigenobu Okazawa (University of Yamanashi)

This paper proposes a crack propagation simulation considering adhesion using a material model and numerical techniques. Multi-material structures that combine steel and composites are essential in various engineering fields, offering light weighting, enhanced strength, and tailored material properties. Conventional numerical simulations employ multiple types of material models to account for the complex deformation behavior. A novel approach uses the damage model, eliminating mesh dependency, and employs numerical techniques to handle crack propagation. Finally, the representative numerical example shows that the novel method is verified.

Unified strength evaluation for various adhesive joints and strength improvement by adding notches

Kazuhiro Oda (Oita University)･Rei Takaki (Nippon Bunri University)･Nao-Aki Noda (Kyushu Institute of Technology)

In this study, the adhesive strength of different edge shapes is evaluated using a method that assumes an edge crack at the interface edge. By comparing the average strength of butt joints and lap joints using the proposed method, it was found that the lap joint has about five times the strength of a butt joint. In addition, the adhesive strength can be improved by providing an additional notch near the interface to reduce the singular stress field at the interface edge.

Comparison of adhesive strength of butt joint and lap joint based on the intensity of singular stress field

Rei Takaki (Nippon Bunri University)･Nao-Aki Noda (Kyushu Institute of Technology)･Yasuaki Suzuki (Suzuki Adhesion Institute of Technlogy)･Kazuhiro Oda (Oita University)

This study investigated the adhesive strength of butt joint and lap joint by ISSF analysis and elasto-plastic analysis when the bond layer dimensions are varied. The butt joint strength can always be expressed as ISSF = constant. On the other hands, In the case of lap joint, when the bonding area is large, the bond strength can be expressed as ISSF = constant. The butt joint strength is constant independent of adhesive area. In the case of lap joints, the adhesive strength decreases with increasing adhesive area.

Improvement of fracture toughness of biomass composite materials using injection molding machine with vent system

Akio Ohtani･Senri Hirata (Kyoto Institute of Technology)

In this study, direct fiber injection molding was used to improve the fracture toughness of wood-blended plastics by incorporating natural fibers. To investigate the dispersion behavior of natural fibers in resin, natural fiber spun yarn and base resin were pretreated before molding, and the effects of the pretreatment methods on dispersion and mechanical properties were evaluated.

Effect of Changes Over Time in the Surface Crystallinity of Polypropylene on Adhesion

Takuo Saiki･Akihisa Otsuki･Haruo Unno (Nissan)

Resinization of car body parts is required to reduce the weight of automobiles, and some resin parts have adhesive joints. In this study, we investigated the adhesive properties of PP with respect to the storage term from injection molding to bonding, and found that the increase in surface crystallinity over time causes a decrease in toughness, which in turn affects adhesive properties.

Study on Fatigue Life Prediction of Lithium-ion Battery Electrode Materials with Stress Ratio

Atsuki Takeuchi･Yudai Furuhata･Yoshinao Kishimoto･Yukiyoshi Kobayashi (Tokyo City University)･Yasushiro Otsuka･Yuki Kawata･Jun Kanai (TA Instruments Japan)･Hajime Okui (Dainen Material)

Lithium-ion batteries are used in electric vehicles, etc., and ignition accidents often occur. The cause of such accidents is the occurrence of internal short-circuits due to damage to electrode materials and separators, but there are few studies on fatigue damage of the electrode materials. In this study, fatigue characteristics of electrode materials with stress ratios were investigated, and fatigue life prediction was attempted when approaching the actual working load.

Evaluation of Dissipated Strain Energy of Lithium-ion Battery Anode Material Using SBR-based Binder by Dynamic Mechanical Analysis

Yudai Furuhata･Atsuki Takeuchi･Yoshinao Kishimoto･Yukiyoshi Kobayashi (Tokyo City University)･Yasushiro Otsuka･Yuki Kawata･Jun Kanai (TA Instruments Japan)･Hajime Okui (Dainen Material)

Damages to electrode materials in lithium-ion batteries, which are used as power sources for electric vehicles and other applications, lead to reduced power generation performance and ignition. In this study, dynamic mechanical analysis has been introduced to establish an evaluation method for the deformation characteristics of electrode materials, and the dissipated strain energy of the anode material fabricated with SBR-based binder was evaluated at various input frequencies.

Experimental Investigation of Fracture Behavior and Regional Strength of Automotive Windshields under Stone Impact

koya sugawara･masaki kawamura (Honda Motor)

This study experimentally investigates the fracture behavior of automotive windshields subjected to stone impacts. The location of crack initiation and the propagation patterns were examined and categorized. The resulting fracture patterns provide a basis for estimating the impact conditions from actual damage, offering valuable insights for improving safety design and post-damage analysis.

Modeling the Drying Process of Fuel Cell Catalyst Inks for Predicting Catalyst Layer Properties

Takanori Sugiura･Yuki Ota･Ryosuke Maekawa･Yuji Kurotani (OYOTA MOTOR CORPORATION)･Yoshiko Ito (Leica Microsystems)･Yuri Nishino･Atsuo Miyazawa (Graduate School of Science, University of Hyogo)

The fuel cell catalyst layer is produced by drying the catalyst ink. The mesoscale structures formed during the drying process influence the material properties of the catalyst layer so that it is necessary to develop the prediction techniques considering the drying process. In this study, we simulate the drying process of the catalyst ink and conduct material properties predictions of the catalyst layer by using the structures from the drying process simulation.

Analysis of Foot Kinematics During Organ-Type Brake Pedal Operation

Shinji Komatsu (SOKEN)･Kengo Ito･Genki Suzuki (DENSO)

This study examines the effects of dimensional variations in organ-type brake pedals, expected to become prevalent with brake-by-wire adoption, on foot kinematics during operation. It highlights how the presence or absence of the separation distance between the rotation axis and pedal surface (pedal surface offset) influences toe flexion during pedal operation, subsequently impacting foot pressure distribution.

Effects of Driver’s Decreased Walking Ability on Pedal Operation

Yui Kato･Machiko Hiramatsu (Nissan Motor)･Naoto Kamide･Masataka Ando (Kitasato University)･Tsuyoshi Sakuma (Nissan Motor)

It is necessary to clarify the physical function elements that lead to the decline in driving ability among elderly drivers. Previous studies have shown a correlation between the pedal operation ability and walking ability of the elderly. In this study, we dissected walking ability into foot movement abilities, such as toe grip strength and ankle range of motion, as well as the transition patterns of vertical ground reaction forces during single-leg stance. We analyzed the effect of these elements on pedal operation ability.

Identification of Driving Behavior and Gaze Behavior of Drivers with Impaired Cognitive Function

Fumito Yamada･Machiko Hiramatsu･Yuki Ito･Tsutomu Kawano･Tsuyoshi Sakuma (Nissan Motor)

To explore methods for the early detection of age-related cognitive decline, we compared the driving behavior of healthy older adults with that of individuals diagnosed with dementia or mild cognitive impairment (MCI). Using a driving simulator, we replicated right-turn scene at an intersection and car-following situations. This study reports on the distinctive driving and gaze behaviors observed in drivers with cognitive impairment.

A Study on Estimation Method of Walking Ability and Cognitive Function by Driving Behavior

Akihiko Ebina･Machiko Hiramatsu･Tsutomu Kawano･Tsuyoshi Sakuma (Nissan Motor)

Examination of a method for estimating physical function deterioration due to aging from driving behavior.
Based on the fact that the pedal operation ability affects the parking behavior, the relation between the driving behavior from the parking start to the end and 2STEP test and TMT of drivers of wide age was examined. To propose a method for estimating function from driving behavior index correlated with walking ability and cognitive function.

Age-Related Changes in Pedal Operation and Their Effects on Driving (4th Report)
-Effectiveness of Pedal Characteristics Considerate of Elderly Drivers-

Machiko Hiramatsu･Akihiko Ebina･Tsutomu Kawano･Yui Kato･Tsuyoshi Sakuma (Nissan Motor)

This study focuses on pedal operations for the development of vehicles and support measures that consider the physical characteristics of elderly drivers. Previous research has shown that the decline in the dexterity of pedal operations associated with aging affects behaviors at stop sign intersections and parking. Additionally, we clarified the pedal characteristics that are easy to operate for elderly drivers and the range of ankle joint angles. In this report, we implemented these pedal characteristics in electric vehicles and confirmed their effectiveness in stop sign intersections and parking situations.

Comparison of Traffic Accident Characteristics Caused by Drivers’ Pedal Misapplications and Gear Shift Errors

Yoko Kato･Yasuhiro Matsui･Michiaki Sekine (NALTEC)

Thus far, the authors have analyzed traffic accidents statistical data to identify the characteristics of traffic accidents caused by pedal misapplications involving elderly drivers. In addition, accidents caused by drivers’ gear shift errors are also considered a type of accidents resulting from human error. This research provides a comparison of the characteristics of these two types of traffic accidents using recent statistical data. We discuss safety measures based on the present analyses results.

Investigating the Impact of Traffic Conditions on Safety Confirmation Behavior under Naturalistic Driving: Towards Driving Assessment for Older Drivers

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

To assess older drivers, naturalistic driving data was analyzed to examine the link between traffic conditions and safety confirmation. High-risk drivers showed notable confirmation deficits at obstructed stop intersections without vehicles.

Investigation of Dynamic Grip Strength Analysis for Establishing a Comprehensive Driving Ability Assessment Index

Ryuma Majikina･Yasumi Ito･Ryuichi Yamada･Takashi Nonaka･Ayumu Honda･Yoshiyuki Kagiyama (University of Yamanashi Graduate School of Integrated Research)･Yuki Tanaka (University of Gunma/Graduate School of Science and Engineering/Electronic Information Division)･Tetsuya Nemoto (University of Yamanashi Graduate School of Integrated Research)

This study aims to establish a comprehensive driving performance evaluation index by examining the correlations between diverse human capabilities, such as essential physical and cognitive functions, and accident propensity. Our proposed methodology involves measuring and analyzing dynamic grip strength, which fluctuates over time, to assess these multifaceted functions. This innovative approach holds promise for simultaneously gauging multiple performance indicators using only dynamic grip strength measurements.

Assessing the Demand for and Behavioral Responses to Aptitude and Safe Driving Training Programs among Elderly Drivers
-Study on Driver Characteristics for Delaying Driving Cessation (47)-

Shunji Taniguchi (Nagoya University)･Issaku Yamada･Norihisa Nomura (Toyota Motor)･Aiko Inoue･Hiroyuki Umegaki (Nagoya University)･Naoshi Koide (Osaka University)･Hirofumi Aoki (Nagoya University)

This study investigated the associations between elderly drivers’ motivations for life safety, health improvement, and safe driving, and the outcomes of online driving aptitude assessments, their engagement in educational programs for safe driving and health promotion, as well as their evaluations of these programs.

Effect of Education Correcting Overestimation on Older Driver's Awareness of Safe Driving

Mayu Yoshikawa (The University of Tokyo)･Hiroshi Yoshitake (Institute of Science Tokyo)･Ryota Fujita･Hiroto Kato (Mitsuibishi Precision Co.,Ltd.)･Motoki Shino (Institute of Science Tokyo)

Older drivers tend to overestimate their own driving abilities. This study experimentally examined the effectiveness of educational interventions designed to correct such overestimation, focusing on changes in their awareness of safe driving. The results revealed that the presence and extent of overestimation correction increased their awareness of age-related decline and burden associated with driving. These changes in awareness were also reflected in subsequent modifications in their driving behavior.

Verification of the Usefulness of a Vehicle Behavior-based Cognitive Decline Detection Technology under Unrestricted Driving Conditions

Yoshito Ogawa･Tatsuya Obuchi (Toyota Motor)

This study reports on the usefulness of a vehicle behavior-based cognitive decline detection technology under unrestricted driving conditions. Currently, a technology has been proposed that detects cognitive decline in drivers using vehicle behavior. In this study, the usefulness of this technology under unrestricted conditions was evaluated with vehicle behavior from the daily driving of older drivers. The results suggested the potential to detect cognitive decline.

Outdoor Evaluation Experiment Under Daytime and Nighttime Conditions on Perception of Automated Driving System Marker Lamps (First Report)
-When a linear marker lamp is installed at the front edge of the roof-

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

In WP29, discussions are being held regarding the requirements for “Automated Driving System (ADS) Marker Lamp” that indicates the status of ADS. In this study, an evaluation lamp with blue-green chromaticity specified in SAE J3134 was mounted on the roof of a passenger vehicle. Outdoor experiments were conducted under both daytime and nighttime conditions to evaluate its visibility as perceived by general drivers under various lighting conditions, including changes in luminous intensity, modulation waveform, and modulation frequency. The study also examined how the lamp was perceived when lit simultaneously with other vehicle lamps, such as direction indicators.

Outdoor Evaluation Experiment Under Daytime and Nighttime Conditions on Perception of Automated Driving System Marker Lamps (Second Report)
-When small marker lamps are installed near headlamps-

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

We investigated the visibility of small blue-green marker lamps, which indicate that the vehicle is in automated driving mode, when they are installed near the headlamp unit of an actual vehicle, both day and night, outdoors. We conducted subjective evaluation experiments on visibility, annoyance, and glare when only the marker lamp is turned on, and also considered how it looks when the direction-indicator and passing-beam are turned on at the same time.

Effects of Angular Velocity and Time Interval of Sequential Visual Stimuli Presented in Driver’s Peripheral Vision on Gaze Guidance for Large-Angle Safety Confirmation

Masanori Takemoto (Seikei University)･Takahide I (Seikei University, Graduate School of Science and Technology)

As a driving support system to facilitate confirmation of pedestrians and bicycles during left turns at signalized intersections, two dynamic visual stimuli moving horizontally were designed and presented in the driver's peripheral vision. This study conducted a simulator experiment to measure gaze data, analyzed the relationship between gaze movement and visual stimuli motion in detail, and examined the effects of the angular velocity and time interval of the two visual stimuli on gaze guidance.

Comparison of ease of search before and after the revision of the safety color

Shimpei Yamada (University of Occupational and Environmental Health)

Safety colors were adjusted from the viewpoint of universal design (JIS Z9103). A comparison of the subjective evaluation of visual search time and ease of searching was made for the safety colors before and after the revision. The safety colors after the revision were evaluated as easier to find, although the visual search time became longer. The causes of this discrepancy and its relationship with traffic signs are discussed.

Research on the Improvement of Pedestrian Visibility for Drivers by Geometric Patterns Projection Lighting

Yoshiro Aoki･Yoko Kato･Michiaki Sekine (National Traffic Safty and Environment Laboratory)

Vehicle-to-pedestrian accidents still occur frequently at night, and effective measures to reduce them are needed. In this research, we investigated effectiveness of a technology that improves pedestrian visibility for drivers by projecting diamond-shaped patterns onto pedestrians from the vehicle’s headlamps. We conducted real-world driving experiments to measure the drivers’ pedestrian recognition distances with this geometric patterns projection lighting and compared the results with those obtained using conventional driving-beam and passing-beam.

Effect of Body Segment-Specific Airflow via a Fan-Integrated Car Seat on Thermal Comfort in a Compensable Hot Environment

Ketaro Wada･Teruyuki Nagai (Graduate School of Science and Technology, Kyoto Institute of Technology)･Tetsuya Kitagwa (Fortech Co. Ltd.)･Yukiko Nishizaki･Naoyuki Yamashita (Kyoto Institute of Technology)

This study examined the effects of airflow via a fan-integrated car seat on thermal comfort in an environment with compensable heat. After walking for 10 minutes, airflow was directed to the backrest (Back), the seat base (Seat), both (Whole Body) or neither (CON). Compared with Seat and CON, whole-body and Back airflow significantly improved overall thermal comfort. These effects were not associated with rectal temperature. These results suggest that back airflow improves thermal comfort when assessed by whole-body measures without a significant change in core body temperature.

Consideration of an Alert Method Using Positional Correspondence Between Seat Vibration and Attention Targets(Second Report)

Yosuke Uemura (Kyoto Institute of Technology)･Tetsuya Kitagawa･Ryuji Furumai (Fortech Co.,Ltd)･Yukiko Nishizaki (Kyoto Institute of Technology)

In a previous report, we showed that responses were significantly faster when vibration from the back was presented from the same direction as the emerging attentional target. In this study, we examined the response-promoting effects of vibration, sound, and a combination of these stimuli. The results showed that the elderly responded better to the combination of voice and vibration than to voice alone when alerted.

Fundamental Study on Vibration Stimulation via an Automobile Seat

Yukiyo Kuriyagawa (Nihon University)･Xinyue Zhang (Nihon University Graduate School)･Hidefumi Koizumi･Shinichi Sagawai･Hiroshi Wakuda･Toshiki Nakamura･Keigo Abe･Kunio Sato (ALPS ALPINE CO., LTD.)

This study aims to realize comfortable and intuitive driving assistance by employing tactile stimuli delivered through seat vibrations, either as an alternative to or in conjunction with audiovisual cues. We investigated drivers’ cognitive responses to seat vibrations with varying frequencies, in contrast to conventional systems that use a fixed frequency.

Research on Active Car Seats for Reducing Car Sickness: Focusing on the Directional Specificity of Human Acceleration Perception Intensity

Masanori Matsuoka･Junya Hoshino (Advics)

An active car seat is proposed to reduce motion sickness in autonomous vehicles. By dynamically driving the car seat in response to vehicle acceleration, the perceived acceleration felt by passengers is reduced, thus preventing motion sickness. Based on the finding that acceleration perception intensity is high in the 30-degree direction above the front of the head, the seat drive amount was set and its effectiveness was verified in real vehicles.

The Estimation of Seated Bone Shape from Ultrasonic Images

Masateru Amano･Yuji Muragishi･Yosikazu Hattori (Toyota central reserach laboratory)

To clarify low-strain sitting postures based on the mechanical structure of bones, we developed a method to estimate the three-dimensional position and shape of bones using ultrasound imaging. Using this method, we examined changes in bone position and alignment in two different sitting postures: slouched and upright. The results showed that the relative position between the sacrum and lumbar vertebrae remained unchanged, indicating that they move together as a single unit regardless of posture.

Preliminary demonstration of internal state estimations for batteries in an in-service EV using a nondestructive diagnosis technique

Kenichiroh KOSHIKA (NTSEL)･Tomokazu MORITA (TOSHIBA)･Toshiki ODA (KANSAI ELECTRIC POWER)･Keizoh HONDA (JET)

Internal state estimations for traction batteries in an in-service EV (manufactured in 2013) using charging curve analysis as a nondestructive diagnosis technique has conducted. We revealed the range of SOH estimation results depending on differences in data sampling methods and analysis methods. The characteristics of battery degradation were also classified based on the estimated internal state of batteries.

Verification of Non-Destructive Diagnosis of Individual Cell Capacity, Cell Balance, and State of Health (SOH) of LIB Battery Pack in the Degradation Process

Tomokazu Morita (Toshiba)･Keizoh Honda (Japan Electrical Safety & Environment Laboratory)･Kenichiroh Koshika (National Traffic Safety and Environment Technology Laboratory)

A cycle degradation test was conducted on a 7-cell series battery pack using automotive lithium-ion batteries. At regular cycle intervals, non-destructive diagnostics were performed using charge curve analysis. The degradation state of the pack was evaluated by estimating individual cell capacities, internal states, and cell balancing conditions. The overall State of Health (SOH) of the battery pack was then calculated. Finally, the estimated SOH was compared with the measured capacity to verify the accuracy of the diagnostic method.

Study on improving cycle durability of anode-free all-solid-state battery (First report)

TAKASHI NAKAGAWA･KYOHEI IZUMI･Shuntaro Ujiie･HAYATE KUSUSHITA (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.

A Power Control Method Utilizing Pre-Operational Information to Extend the Lifetime of Fuel Cells in a Fuel Cell Hybrid Test Train

Takashi Yoneyama (Railway Technical Research Institute / Waseda University)･Sihai Xu･Shengen Hsu･Minhao Wen･Yida Bao･Wei-hsiang Yang･Yushi Kamiya (Waseda University)･Kenichi Ogawa･Takamasa Yamada･Manato Kaneko (Railway Technical Research Institute)

This study proposes an output power control method for a fuel cell hybrid test train that utilizes pre-operational information such as track gradient and passenger load factor. While conventional methods rely solely on the current state of the train—such as the battery state of charge (SOC) and traction converter output—as inputs for control, the proposed method incorporates pre-operational information into the control strategy. The impact of the method on fuel cell degradation is quantitatively calculated through a simulation.

Battery-in-the-Loop (BiL): A Real-Time Testing Methodology for Battery Electric Vehicle (BEV) Battery Evaluation

Phil Roberts･Yoshikazu Nagasawa (HORIBA Ltd)･Richard Stocker (HORIBA Instruments Ltd)･Tae Hwa Lee (HORIBA Ltd)

Battery Electric Vehicle adoption is outpacing advancements in battery technology. To compensate for low energy density, manufacturers install larger packs to ease range anxiety. Traditional characterisation methods are slow and not reflective of real-world use. This study introduces a Battery-in-the-Loop system combining HORIBA STARS, a battery cycler, physical battery, and IPG CarMaker simulation. Real-time drive cycles enable dynamic testing across chemistries and conditions, allowing manufacturers to optimise battery selection based on realistic performance metrics.

Investigation of Impedance Measurement Methods for EV Traction Batteries Mounted on EVs

Takumi Mori･Nozomu Teranishi (HIOKI E.E. CORPORATION)･Toshimichi Takahashi (Meidensha)

It is important to establish and standardize a method to measure and evaluate the electrical characteristics of EV traction batteries mounted on EVs as an inspection methodology for EV performance and safety. In this study, multiple methods for measuring the internal resistance/impedance of battery packs mounted on EVs were evaluated. The experiment results and comparative investigation is reported, to propose an appripriate and versatile method.

Development of Simulation Technologies for Efficient Parameter Design in xEV Driving Control

Takuya Morikawa･Takashi Kaminaga･Motoyuki Kimata･Yuya Nagasawa･Hirotaka Kaneko (Toyota Motor)

For improving the efficiency of parameter design in xEV driving control by utilizing simulation, elements that affect parameter design under various driving scenarios have been modeled based on physics throughout the entire vehicle system. Additionally, efficient parameter design process has been built by integrating the developed models with simulation techniques such as continuous automated execution.

HEV Transaxle Loss Estimation Using Integrated Physical and Experimental Model

Motoyuki Kimata･Takuya Morikawa･Hirotaka Kaneko (Toyota Motor)

In the parameter design of HEV driving control, it is important to consider not only the outputs of the engine and motor, rolling resistance, and aerodynamic drag, but also internal resistance, such as transaxle loss, especially under various operating conditions. To address this, an integrated loss estimation model was developed by combining a physical model, based on fundamental specifications of bearings and gears, with an experimental model that captures factors difficult to represent physically, such as oil level and lubrication conditions.

Study of Model Based Design of Engine Stop Control Parameters in xEV

Takashi Kaminaga･Takuya Morikawa･Hirotaka Kaneko (Toyota Motor)

Engine stop control is one of the most complicated parameter design items in xEV as it consists of large number of maps and constants. For simplification, reinforcement learning has been adapted with a reward function delivered from the basic functional requirements. Then, this has been translated into a simple physical formula for generalization which can be applied to vehicle development and enhance parameter design efficiency.

Development of Look-ahead Energy Management Control for Electric Commercial Vehicles with Route Information

Naohiko Matsuura･Masahiro Suzuki･Hidemasa Takayama (Hino Motors)

In this study, look-ahead energy management control using route information, such as traffic, geometry, temperature, is developed for the purpose of improving energy consumption of electric commercial vehicles. Developed controller is configured with an artificial neural network model learned with the optimization theory of dynamic programming on the condition of performing on on-board ECU, and computer simulation is conducted for heavy duty electric truck to verify the effectiveness of the controller.

Accelerating powertrain development cycles with GenAI

Jan Nowack (FEV Europe)･Jin Izawa (FEV Japan)

System development faces challenges due to the multi-dimensionality of conceptual solutions in control and design domains, particularly regarding derived use-cases. To address these challenges, FEV proposes integrating the vehicle powertrain system design and controls tool into customers' system development. This integration leverages frontloading capabilities and cost reduction potentials through early-phase design. Additionally, the AI-based vehicle powertrain system design and controls tool will accelerate efficient and faster development.

Verification of market suitability of ultra-low-floor light duty BEV trucks for last-mile delivery

Yusuke Takenaka (Hino Motors)

HINO Motors have developed and launched the ultra-low-floor small BEV truck "Dutro ZEV" that solves vehicle issues at logistics sites in last-mile delivery while also achieving a carbon-free environment.
In this presentation, we will report on the results of verification of market suitability for the vehicle concept and performance/function specifications, and propose future challenges.

Air Conditioner Drive System for Dual-motor EV Using Planetary Gear Transmission

Noritaka Matsuo (Matsuo Engineering Office)

In an EV equipped with an air conditioning system that directly cools the entire drivetrain with refrigerant, energy consumption of a conventional electric compressor system with integrated motor and compressor and a motor-compressor separated drive system in which the power of two traction motors is split into for traction and for compressor drive by a planetary gear transmission was compared by simulation, and the separated drive system proved to be better.

Development of Interactive Manual Drive

Yoichiro Isami･Tatsuya Imamura･Ryohei Yuasa･Toru Shinagawa･Yuji Iwase (Toyota Motor)

A device for shifting in BEVs and a control system that generates vehicle responses (such as driving force, sound, and meter) based on the driver’s actions have been developed, enhancing the joy of driving (including power control, shifting operations, and shifting feel). By applying a simple physical model to the control system, a highly extensible platform has been created, allowing for the development of diverse configurations.

The Formula One Turbo Hybrid Engine has calculated and measured Efficiency of 50% (The Third Report)
-Use of Synthetic Gasoline in Formula 1 Final suggests Solution to Oil Depletion Problem-

OSAMU FUJII (Renewable Energy Research Institute TRB)

The Formula 1 Engines are turbo hybrids with 1040 horsepower and an measured efficiency of 52.3%. The fact that the winning team in the 2021 Formula 1 finals achieved this efficiency using synthetic gasoline proves that synthetic gasoline has the highest efficiency and maximum output. Since synthetic gasoline is made from renewable energy, it can be used forever, suggesting that the problem of oil depletion can be solved.

Development of a prediction method for oxidative degradation performance in coolant for electric vehicles

SHINYA ASAURA･HIROYUKI HISATA･YASUAKI KODAMA･MIKIO TAKEDA･YUJI NOYORI･KAZUMI SUZUKI (Toyota Motor)

As vehicle development becomes more complex, using actual machine-based development methods leads to an increase in workload. Therefore, simulations are being utilized; however, simulating the time-series degradation of coolants, which involves chemical changes, is challenging. In this study, we developed a method to predict the time-series degradation of coolants by utilizing known data about the basic properties of materials and 3D fluid simulations.

Evaluating the effectiveness of a lighting system that alerts drivers to pedestrians they may have missed.

Maho Irita･Ayumi Nishikawa･Akifumi Yamamoto･Shiori Shimaya･Yang Han (MitsubishiElectric)

Automatic Emergency Braking (AEB) is effective in reducing pedestrian accidents, but many drivers report feeling fear when it activates. To achieve greater safety and peace of mind, our company considers it essential to reduce such fear-related near-miss experiences. Therefore, we are developing a system that alerts drivers to the presence of pedestrians before AEB is triggered, helping them become aware earlier and potentially avoid emergency braking situations.

Trajectory prediction and planning using combinatorial optimization in highway merging scenarios.

Koji Oya･Hiroshi Fujimoto (Mirise Technologies)･Yoshiaki Irie･Tomoaki Morimoto (Toyota Motor)･Kota Matsuura･Kenshin Yamamoto (Mirise Technologies)

Highway merging task requires predicting the trajectories of other vehicles and planning the trajectory of ego vehicle performing lane changes with appropriate relative speed and distance within a limited time and space, and it is one of the most challenging tasks in autonomous driving. To obtain a desirable solution from the combination of multiple vehicle trajectories, we devised the use of combinatorial optimization and conducted verification using a quantum-inspired machine.

Development of Localization Function for Achieving Autonomous Driving in Failing Environment of GNSS

Takahiro Sakai･Noriyasu Hasejima･Teppei Saitoh (Hitachi)

We developed a method to enhance localization function by integrating the results of GNSS, dead reckoning, point cloud matching, and template matching to realize autonomous driving systems in environments where GNSS is unavailable. As a result, we confirmed that autonomous driving can be sustained in GNSS-denied environments and that we can minimize tracking errors along the target trajectory.

Development of a Remote Driving Function Using a Digital Twin Environment Constructed with High-Resolution 3D Models

Noriyasu Hasejima･Kenta Maeda･Yoshibumi Fukuda･Tsuyoshi Kitamura･Hiroyuki Yamada･Naoyuki Tashiro (Hitachi)

To realize unmanned operation of autonomous driving services, the remote assist function is considered one of the key technologies as a backup for emergency situations. In this presentation, we report on the development of a remote assist function with low communication bandwidth that supports the process from stopping to resuming autonomous driving, by reflecting driving commands in a digital twin environment that reproduces the real world as a high-resolution 3D model.

Precise Docking Control of Urban Autonomous Driving using Multiple-Coordinates-based Cost Function

Hidemi Ando･Yuki Shiozawa･Takashi Fukushige (Nissan Motor)

In urban autonomous vehicles used for mobility services, it is essential to approach and stop at precise docking positions, avoiding parked vehicles and other obstacles to facilitate passenger boarding and alighting. In this study, we developed an MPC framework that combines a cost function for precise docking evaluation in Cartesian coordinates with an obstacle avoidance evaluation in Frenet coordinates. The proposed method was validated through real-world vehicle experiments.

Proposal for Stuck Vehicle Escape Control Using Tire Position Prediction in a Depression Based on Acceleration

YUJI HARA･KENTARO NISHIDA･TAKAHIRO YOKOKAWA･YOSHIYUKI IMASHIOYA (Toyota Motor)

There is a need for off-road autonomous driving to improve automobile safety. Particularly, getting unstuck requires advanced driving skills, and for those without these skills, the worst-case scenario is that they may be unable to move the vehicle at all. Therefore, this research proposes a function to get unstuck by estimating the tire's position in a depression based on acceleration and controlling the driving force according to that position.

Straight Path Tracking Control of a Trailer for Car-Caravan Type Articulated Tracked Vehicles Using Time-State Control Form

Bunji Mizukami･Yuichi Chida･Masaya Tanemura (Shinshu University)

In car-caravan type articulated tracked vehicles consisting of a tractor controlled by velocity and angular velocity and a trailer without driving force, we devised a transformation into a time-state control form along with control input conversion. This approach enabled straight path tracking of the trailer while avoiding jackknifing. The effectiveness of the proposed method was verified through simulations.

Development Methodology of ADAS Calibration Testing Utilizing Hub-coupled Vehicle Testbed

Tomoki Taira･Masaki Sagawa･Kenji Suemasu･Hirotaka Kaneko (Toyota Motor)

In order to improve development accuracy and efficiency in ADAS field, a development process re-engineering is implemented using hub-coupled vehicle testbed. In this paper, the way how to set up automated calibration platform system collaborated with measurement, peripheral vehicle models, and driver operation, is reported. This system is applied to vehicle evaluation project.

Investigation into Start Evaluation Issues in ADAS Calibration Utilizing Hub-coupled Vehicle Testbed

Masaki Sagawa･Tomoki Taira･Kenji Suemasu･Hirotaka Kaneko (Toyota Motor)

Until now, hub-coupled vehicle testbed has been primarily used for powertrain evaluation, but its application has recently expanded to include the assessment of Advanced Driver Assistance Systems (ADAS). For ADAS, evaluation also covers stop-and-go behavior, resulting in a broader operational domain compared to traditional powertrain testing, which has introduced new challenges. This paper discusses the issues related to start behavior caused by the tire model when evaluating ADAS functions using hub-coupled vehicle testbed, along with corresponding countermeasures.

Assessment of AVPS (Automated Valet parking Systems) CRC Functionality

Yasuhiro Yamasaki (Chukyo university)

The communication interface for Automated Valet Parking Systems (AVPS) is defined by ISO 23374. In accordance with this ISO standard, the German Association of the Automotive Industry (VDA) has issued a requirements document for AVPS. This document defines AVP as the communication protocol for AVPS and applies CRC32K9 to messages that are assigned an ASIL/SIL level. This paper evaluates the fault detection capability of CRC32K9 as a safety mechanism.

Correlation between ESA immunity test methods

Shinichiro Itoh･Keiji Kobayashi (National Traffic Safety and Environment Laboratory of National Agency for Automobile and Land Transport Technology)･Hitoshi Tsukahara (Japan Quality Assurance Organization)

Although various ESA immunity test methods are specified in ISO11452, there is no description of the correlation between these test methods.
Therefore, we investigated a method for verifying the correlation between these test methods and carried out comparative measurements of the main measurement methods among them, the ALSE method, the BCI method, and the RVC method.
In this papar, an overview of these results is reported .

Performance Evaluation of Advanced PAD Structure for HOD System

SEOKHWAN JI (KOMOS)

This study evaluates the core PAD structure developed by HOD (Human Occupant Detection) system. A series of electrical, thermal, mechanical, and material density tests were conducted to verify resistance, capacitance stability, and durability under varied environmental conditions. The new structure demonstrates superior voltage endurance and sensitivity compared to conventional designs. Test results confirm its robustness against temperature, humidity, and structural damage. These findings provide a reliable foundation for future mass production and design optimization of high-performance HOD sensing modules.

Mitigating Automotive Cybersecurity Risks in Software Containers for Software-defined Vehicles
-How Edge AI Is Transforming Vehicle Threat Detection-

Ian Chu (Architect at VicOne)･Hara Seiki (Senior Director, Engineering Department at VicOne)

Automotive manufacturers use container technology to streamline software-defined vehicle (SDV) development, offering lightweight, portable, and isolated environments that boost scalability, testing, and deployment. However, containers introduce new security challenges. Given evolving threats, AI-driven security with self-learning capabilities is essential to detect and adapt to emerging attack patterns, enhancing accuracy and response. This paper examines container-related attack vectors in SDVs and underscores the need for proactive, intelligent security strategies throughout the automotive software lifecycle to ensure system resilience in a connected environment.

From Emissions to Cybersecurity: Navigating Euro 7's New Compliance Landscape
-A Practical Path to Compliance through Strategic Adaptation of Existing Cybersecurity Frameworks-

Shin Li (Staff Engineer, Threat Research at VicOne)

EEuro 7 shifts from emission thresholds to cybersecurity, addressing tampering risks in emission control systems. By redefining TARA to focus on system awareness over traditional IT security, Euro 7 introduces unique compliance demands. Our analysis with Initiative 14333 shows that manufacturers can meet these requirements through minimal, strategic updates to existing frameworks. This presentation highlights our practical approach and core methodologies designed to fulfill the stringent yet targeted cybersecurity mandates of Euro 7 efficiently and economically.