Direct yaw moment control of electric vehicle with 4 in-wheel motors to improve handling and stability 2020-01-0993
More and more OEMs are studying the in-wheel motor driven vehicle. One of the in-wheel motor driven vehicle key technologies is multi-motor torque distribution and control. This paper proposes a direct yaw moment control strategy to improve 4 in-wheel electric vehicle handling and stability. The control method consists of three components: feedback control based on target yaw rate, feedforward control based on current lateral acceleration and deceleration control based on under/oversteer situation. Feedback control is used to follow the driver’s target yaw rate and improve the vehicle yaw rate response and stability. The target yaw rate is calculated by two-freedom vehicle model and limited by lateral acceleration and vehicle current steering condition. So we don’t need the vehicle side slip angle or road adhesion coefficient information to prevent excessive target yaw rate, which are very different to obtain. The feedforward control is used to reduce the vehicle understeer characteristic when accelerating in a curve and increase the vehicle yaw rate. The deceleration control can reduce the driven torque of each motor to slow down the vehicle when in critical steering condition. The proposed control strategy was verified on a 4 in-wheel motor electric vehicle and the experiment result indicated that it can reduce vehicle understeer characteristic in steady steering condition, improve vehicle yaw rate response in transient steering condition and enhance vehicle steering stability in critical steering condition. Furthermore, it is able to achieve an “on-the-rail” feeling that is quick, linear, and highly stable, which can increase the driving fun.
Yongqiang Zhao, Jinlong Cui, Zehui Zhou, Yang Fang, Deping Wang, Tianqiang Zhang, Aibin Wu, Qichun Sun, Yang Zhao
College of Automotive Engineering Jilin University, China FAW Group Corporation