Performance-Guaranteed Adaptive Switching Fault-Tolerant Control of Steer-by-Wire System Considering Actuator Fault and Load Disturbance

In order to meet the requirement of a higher safety level for the steer-by-wire (SBW) system, this article proposes a dual-motor SBW (DMSBW) system to realize its safety redundancy function. Aiming at the problem of vehicle tracking performance degradation when the steering motors of the DMSBW system have serious failures, a performance-guaranteed adaptive switching fault-tolerant control (FTC) strategy is designed. First, considering the actuator faults and the caused load disturbance, the DMSBW system switching control model is established. Then, to guarantee the tracking performance of DMSBW system before and after switching FTC, the performance-guaranteed adaptive backstepping switching controller based on the extended state observer (ESO-PABSC) is designed. The expanded state observer estimates the state of the system and the perturbation of the load torque. Considering the parameter uncertainties existing in the system, the control output of the DMSBW system is solved by the performance-guaranteed adaptive backstepping controller, and the dynamic switching controller is designed to perform dynamic switching when the steering motor fails, which ensures that the tracking error of the system is within the prescribed performance. Finally, the effectiveness of the proposed control strategy under the actuator stuck fault is verified by the simulation and experiment. The results show that the proposed ESO-PABSC algorithm improves the vehicle tracking performance by 56.7% and 72.9% compared to the PBSC and Hinf algorithms, respectively.

I. Introduction

As an emerging automotive steering system, the steer-by-wire (SBW) system is an indispensable component in the future development of unmanned vehicles [1], [2]. It sends control commands to the steering actuators through electronic signals to select autonomously the steering ratio, which makes the steering performance more precise and flexible [3]. However, in the absence of traditional mechanical connections, SBW systems are susceptible to component faults and unforeseen environmental changes [4], [5]. Therefore, enhancing the fault tolerance and reliability of SBW systems becomes a pressing challenge in the field of SBW research.