Abstract: In-wheel motors drive electric vehicles can independently control the driving/braking torque of each wheel, and can significantly improves the dynamics control ability of the X-by-wire chassis through the coordination control of the driving, braking, steering and suspension system. However, the simple superposition of the control functions of the various subsystems of the vehicle cannot exert the control performance of the entire vehicle. In order to improve the stability control effect of vehicle with X-by-wire chassis, a coordinated control method for space stability that integrates front-wheel active steering, four-wheel differential drive and active suspension control is proposed. At first, the vehicle dynamics simulation model is built and the characteristics of vehicle instability process is analyzed. Then, the chassis cooperative control framework is constructed, the vehicle state expectation and the intervention conditions of active suspension system are calculated, and the weight distribution method of active front steering and four-wheel differential drive direct yaw moment control is designed. At last, an active front steering controller based on model predictive control, a direct yaw moment controller based on sliding mode control and an active suspension system controller based on non-singular terminal sliding mode control are designed and the simulation verification is completed. The research shows that the proposed chassis cooperative control strategy can ensure the safety and stability of the vehicle on roads with different adhesion conditions. The completed research provides a new idea for the development of X-by-wire chassis integrated control strategy.

Key words: electric vehicle, in-wheel motor, X-by-wire chassis, vehicle dynamics, cooperative control