Modal Analysis Approach on Vehicle Transient Behavior
-Considering Roll and Pitch Dynamics-

Kaoru Kusaka･Takahiro Yuhara･Shingo Koakutsu (Honda Motor)

Vehicle dynamics are primarily governed by planar motion; however, roll and pitch significantly influence handling and subjective evaluation. Prior studies suggest that phase differences between roll and pitch during turn-in affect driver perception. While modal analysis has been applied to motorcycles, its use for four-wheel vehicles remains limited. This study formulates a four-degree-of-freedom model incorporating roll and pitch and solves the complex eigenvalue problem analytically to extract vibration modes. Furthermore, by demonstrating that vehicle behavior results from the superposition of these modes, the underlying mechanism of sprung-mass motion is elucidated.

Analysis of Handling Stability under Combined Steering and Road Irregularity Inputs (Second Report)

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

In the first report, a 5-degree-of-freedom motion model considering road surface irregularities was constructed, and the influence of suspension friction on handling and stability was analyzed. In this report, the effect of front-rear wheel friction force difference on the initial alignment effect is investigated, and it is shown that, under certain conditions, the yaw damping effect is less than the lateral force understeer. Similarly, an analysis will be conducted on the stroke velocity dependence of the damping force.

Theoretical Derivation and High-Accuracy Refinement of an Approximate Eigenvalue Formula for Steering–Vehicle Systems under Force Control

Hideki Sakai (Kindai University)

The author classifies steering feel into three components: 1) the quasi-static angle–force characteristics, 2) the rear-wheel lateral force transmitted to the steering wheel, and 3) the steering wheel's response to steering torque. The last component is referred to as force control, whose characteristic equation becomes a fourth-order equation because the steering system and the vehicle system are coupled. Intuition was used in formulating high-accuracy approximation formulas for their resonance frequencies. In this paper, we theoretically derive these formulas based on analytical considerations and further improve their approximation accuracy.

Upstream Design Support for Chassis Components Based on a Hierarchical 1D Model and Sensitivity Analysis

Tetsuhiro Tanabe･Junichi Ichimura (Newton Works)

This study investigates an upstream design support method for chassis components using a 1D-CAE vehicle dynamics model. The relationship between vehicle dynamics targets, with a focus on handling stability, and chassis component parameters is represented in a hierarchical structure, and sensitivity analyses based on vehicle responses to steering inputs are performed to support design decisions in the upstream design phase.

Mathematical Model of Vehicle Dynamics for Drifting in Motor Sports

Yoshio Adachi

Drifting in motorsports utilizes traction force as centripetal force during cornering; therefore, modeling of the traction force is indispensable. In this study, we introduce a vehicle model that incorporates a kinetic-friction tire model focusing on contact patch velocity, enabling analytical calculations. Furthermore, we examine the steering angle and slip angle in drifting of four-wheel-drive vehicles.