タイヤ非線形領域における4WS車両の安定性向上の理論的解析

抄録

4WS is a system developed to improve handling characteristics. In the tire linear region, the transient characteristics and sideslip angle of the vehicle can be controlled. However, 4WS is said to be less effective in tire nonlinear regions with high lateral acceleration. In this paper, the effects of 4WS in the nonlinear region were investigated using state transition vector diagrams. Unlike trial-and-error time-series simulations, the state transition vector diagram captures the entire vehicle motion state at each time. In the case of 4WS, the tire attack angle differs by the same amount as the rear wheel steering angle in all conditions. Therefore, 2WS and 4WS can be easily compared by shifting the state transition vector group left and right in parallel. As a result of the study, it was theoretically shown that 4WS can be on a more stable state transition trajectory than 2WS, and that it has a larger margin to reach the instability boundary.