PID slip control based on vertical suspension system for in-wheel-motored electric vehicles

A slip controller for in-wheel-motored electric vehicles (EVs) based on PID theory is proposed in this paper. Half-vehicle vertical vibration model and the vehicle body dynamics model are built to research longitudinal dynamic performance of EVs. The effect of vertical force transfer on tire is analyzed to describe vehicle movement accurately. Based on the model, PID slip controller is designed. The longitudinal slip of front wheel and rear wheel are controlled in the stable range through controlling the torque of the wheels. Finally, the effectiveness of the proposed controller is verified in the MATLAB/Simulink. The longitudinal slip ratio of the wheel can catch the optimal longitudinal slip in three seconds. Slip is maintained between 0 and 0.08 when accelerating, or -0.08 when braking. The wheels are prevented from getting locked or slipped to ensure safety of the vehicle.