Road Feel and Return Control on Low Friction Coefficient Road for Steer-by-wire Vehicles

Since the partial mechanical connections between the steering wheel and the front wheels are cancelled in the steer-by-wire(SBW) system, the steering resistance torque of vehicle can't be directly feedback to the driver. Based on the analysis of the generation principle of the traditional vehicle road feeling, the steering motor current measured by current sensor is used to be as equivalent the road load, and the self-design of road feeling of SBW is realized. By establishing the model of SBW and utilizing the information of the self-aligning torque, considering that the self-aligning torque of vehicle will decrease significantly on low friction coefficient road, a new returning control strategy is proposed, which uses the extended Kalman filter algorithm to estimate the road adhesion coefficient, and designs different return current according to different road adhesion coefficient, so as to make sure that the designed SBW system has good return ability on all kinds of pavement. Finally, the simulation and the hardware-in-the-loop test are implemented to verify the method, the results show that the designed road feeling satisfy the driver's handling needs well. The returning control strategy proposed in this paper greatly improves the driver's perception of road feeling on low friction coefficient road.