Research on Torque Allocation of Four-Wheel Independent-Driving Electric Vehicles Based on Stability

Abstract

A torque allocation method of PID (Proportion-Integral-Derivative) control based on BP (Back-Propagation) neural network is adopted to investigate the stability of a four-wheel independent-driving electric vehicle under extreme driving conditions and to control both yaw rate and sideslip angle. The main characteristic parameters of the stability are analyzed first, and the control variables are determined. Finally, the torque allocation control strategy for an independent-driving electric vehicle is designed. The controller has two layers: upper and lower. In the upper layer, according to the demand of longitudinal force, the PID control method is designed for speed control, and the PID controller based on the BP algorithm is set up to control the yaw moment created by yaw rate and side-slip angle. In the lower layer, a fuzzy control method is adopted to control the slip rate. Finally, the designed control system is simulated. Results show that the designed torque allocation control strategy ensures driving safety and vehicle stability under extreme driving conditions.