Optimization Control for 4WIS Electric Vehicle Based on the Coincidence Degree of Wheel Steering Centers

The steering centers of four wheels for passenger car do not coincide, which may result in tire wear and the unharmoniously movement of the vehicle. In this article, an optimization control method for Four Wheel Independent Steering (4WIS) electric vehicle based on the coincidence degree of steering centers is proposed, to improve the driving performance. The nonlinear vehicle model of the four-wheel independent steering vehicle is established, and the formula of the wheel steering center is derived. The coincidence degree of wheel steering centers is defined as the evaluation index, to describe and evaluate the performance of the coordination for wheels’ movement. Meanwhile, the structure design of 4WIS system and the establishment of Direct-Current (DC) steering motor model are carried out, and the Model Predictive Control (MPC) controller for steering actuator is designed. The coincidence degree and related performance index for 4WIS vehicle steering system are performed as the optimization target for vehicles to achieve the optimal control by neural network predictive control algorithm. Simulations based on high-fidelity CarSim model show the effectiveness of the control approach.