Speed-dependent coordinated control of differential and assisted steering for in-wheel motor driven electric vehicles

In this paper, we present a coordinated control system of differential and assisted steering for in-wheel motor driven (IMD) electric vehicles (EVs) with two independent front-wheel drives. An electric differential (ED) control strategy is proposed to track the expected yaw rate based on sliding mode control (SMC). Meanwhile, to realize differential drive assisted steering (DDAS), a variable speed integral PID controller is used to follow the ideal steering wheel torque. The impacts of the coupling with the ED and DDAS systems on EVs are analyzed, and a coordinated control system with adaptive weighting dependent on vehicle speed is designed. Results of the simulation on the CarSim-Simulink joint platform for IMD EVs model show that the proposed coordinated control approach can effectively reduce the torque of a steering wheel while ensuring the vehicle’s stability. Finally, road testing results of IMD EVs are demonstrated to be comparable with joint simulations, indicating the correctness of this solution.