Handling stability control strategy for four-wheel hub motor-driven vehicle based on adaptive control for road adhesion

Handling stability control can improve the safety of four in-wheel motor independent-drive electric vehicle (4MIDEV). An adaptive motion state control strategy based on improved sliding mode control for 4MIDEV is proposed to improve the steering stability control of the vehicle under different adhesion conditions. This adaptive control strategy uses a multi-layer structure, which mainly includes a motion reference layer, an upper-layer motion controller, and a lower-layer torque distribution controller. Aiming at the non-linear dynamic characteristics of 4MIDEV under different adhesion conditions, a dynamically parameter-varying motion reference layer is constructed to improve the accuracy of the reference values of sideslip angle and yaw rate, and realize the joint control of them. Considering the adhesion coefficient, construct the comprehensive yaw rate state variable, and use the improved sliding mode control algorithm to calculate the expected yaw moment. The lower-level controller uses the optimal distribution method to distribute the torque of each drive wheel in combination with the adhesion coefficient. By constructing a joint simulation platform of Carsim and Simulink, simulations under different road adhesion conditions are realized, verifying that the proposed improved strategy can effectively adapt to different adhesion conditions, while improve the handling stability of 4MIDEV.