Fault-tolerant Control Strategy for Steer-by-wire Vehicles Using Rear-wheel Steering

In this paper, a fault-tolerant control strategy for steer-by-wire (SbW) vehicles was proposed. Because steering motor failures in SbW vehicles can lead to fatal accidents, ensuring reliability and fault tolerance is crucial. In most studies, dual steering motors on the front axle have been used to achieve hardware redundancy. Few studies have focused on the development of fault-tolerant control strategies by using the rear-wheel steering system. In this study, a nonparallel hardware redundancy structure was proposed using a four-wheel steering system. A disturbance observer was designed to estimate the loss in the effectiveness of steering motors. The proposed fault-tolerant control strategy includes two approaches depending on the severity of the motor failure. In the first approach, the target steering value is increased when the motor failure is not serious, resulting in the desired turning behavior. However, this approach cannot sufficiently cope with serious failure situations, such as a complete failure of the motor. Therefore, in the second approach, a serious front-wheel steering motor failure is compensated by active rear-wheel steering. The fault-tolerant control performance of the proposed strategy was validated by conducting computer simulation studies using Carsim and MATLAB/Simulink. © ICROS 2023.