Event-triggered active return-to-center control for steer-by-wire system by a time-window algorithmic framework

Since the mechanical decoupling of the steer-by-wire system, the self-aligning torque from the vehicle tire cannot be transmitted to the steering wheel. As a result, the steering wheel does not automatically return to the center position after the driver releases the steering wheel. In order to design an active return-to-center (RTC) steering system, this paper proposes an event-triggered active RTC control for the steer-by-wire system by a time-window algorithmic framework. The active return state is worked by the slide mode control to track the steering wheel RTC speed reference. For the SBW system, an RTC speed reference model is designed to obtain referable kinematic characteristics of an ideal mechanical steering system. Additionally, an active return transition module for RTC state switching is designed by a time-state sequence transfer mechanism, which is used to reduce the jerking sensation during the transition between normal steering and active returning states. To evaluate the effectiveness of the proposed algorithms, a hardware-in-the-loop test platform with a steer-by-wire system is established. Based on the different experimental scenarios, the performance of the proposed active RTC control approach is verified by comparative analysis.