Abstract:

A differential power steering control method was proposed based on variable universe fuzzy proportional-integral-derivative (PID) to improve the steering lightness of an in-wheel-motored electric vehicle. A steering system model and an ideal power assist characteristic model were established to obtain the ideal steering wheel torque during vehicle steering. According to the deviation of steering wheel torque and the change rate of the deviation, the PID control parameters were adjusted and the torque distribution control of the four wheels were realized. PID was used to control the slip rate of the wheels to avoid excessive wheel slip. Numerical simulation based on CarSim and MATLAB/Simulink software was used to analyze the control performance. The results show that the vehicle steering lightness improvement under variable-domain fuzzy PID control is 43.5%, and the error rms of the yaw rate is 0.212 rad/s. The proposed control method can improve the accuracy of steering wheel torque tracking ideal torque, and effectively realize the wheel slip rate control.

Key words:  in-wheel-motored electric vehicle ,  differential power steering , fuzzy PID contro l variable universe ,  slip ratio control