Yaw and lateral stability control for four-wheel-independent steering and four-wheel-independent driving electric vehicle

Abstract

Based on the traditional four-wheel steering system, this paper combines the steer-by-wire system and four-wheel-independent driving technology to develop a new steer-by-wire four-wheel-independent steering and four-wheel-independent driving electric vehicle, which can realize four-wheel-independent steering and four-wheel-independent driving. Aiming at the steering actuator redundancy characteristics of the four-wheel-independent steering and four-wheel-independent driving vehicle, a hierarchical control method is proposed in this paper. In view of parameters perturbation of vehicle speed and tire cornering stiffness and the model uncertainty problem, the structure singular value μ is used to study the stability control of four-wheel-independent steering and four-wheel-independent driving vehicle under multiple perturbations in the upper layer, and verifies the advantages of μ controller by comparing it with H∞ control and proportional-integral-derivative control. The lower layer is aimed at the redundancy of vehicle steering actuator, an on-line reconfigurable steering angle and driving force allocation control method based on tire force optimal allocation is proposed. This method can not only optimize the tire longitudinal force and lateral force distribution under normal conditions but also reconstruct the distribution control strategy on-line under fault conditions, realizing active fault tolerance. Finally, simulations by MATLAB/Simulink and hardware-in-the-loop experiments are conducted to verify the proposed control method. The simulation results show that the designed controller can maintain good stability under the conditions of model perturbation, separation pavement, and actuator failure.