Robust H∞ output-feedback yaw control for in-wheel-motor driven electric vehicles with differential steering

This paper investigates the yaw control problem for in-wheel-motor (IWM) electric ground vehicles (EGVs) based on the differential steering in the presence of the complete failure of the active front-wheel steering. Differential steering is an emerging steering mechanism, generated from the differential torque between the left and right wheels in IWM EGVs. In case that the regular steering system is defective, differential steering can be utilized to act as the sole steering power, and thus avoid dangerous consequences for vehicles. For this purpose, a robust H∞ output-feedback controller based on differential steering is designed to achieve yaw stabilization, considering the desired steering angle is uncertain and hard to obtain. The front steering angle is provided by the differential driving torque generated by independently actuated IWMs mounted in the front wheels. Parametric uncertainties for the cornering stiffnesses and the external disturbances are considered to make vehicle robust to different driving conditions. CarSim-Simulink joint simulation results based on a high-fidelity and full-car model have verified the effectiveness of the proposed controller to guarantee the equal handling and stability.