Fault diagnosis and reconstruction strategy of redundant motors and sensors in steer-by-wire system

In the steer-by-wire (SBW) system of autonomous commercial vehicles, the dual-motor steering actuator acts as the sole steering power source. Motor or related sensor failures directly impair steering functionality and even cause traffic accidents. To address this issue, this paper proposes a fault diagnosis and reconstruction strategy for the SBW system of autonomous commercial vehicles. First, the structural principle and fault types of the dual-motor SBW system are analyzed, and a mathematical model is established. Next, the system’s fault diagnosis and reconstruction process is elaborated: targeting faults at different locations, fault factors are calculated using an adaptive Sliding Mode Observer (SMO), Square Root Cubature Kalman Filter (SRCKF), and three-phase current coordinate transformation, respectively. Meanwhile, fault flags are set based on the calculated fault factors to switch corresponding control modes. A reconstruction control strategy integrating hardware redundancy, software redundancy, and hierarchical degradation is further proposed to enhance the SBW system’s safety and stability. Finally, hardware-in-loop (HIL) experiments verify the effectiveness of the designed strategy.