Fault-tolerant control of off-road vehicle steering based on motor torque compensation and differential steering

Steering actuator faults can seriously degrade the path-tracking accuracy and driving safety of unmanned off-road vehicles operating in complex environments. Existing fault-tolerant steering methods often focus on a single fault mode, while the coordinated diagnosis, classification, and reconfiguration of different steering motor faults remain insufficiently addressed. To improve the steering reliability of off-road vehicles, this paper proposes a fault-tolerant control strategy based on motor torque compensation and differential steering. The proposed framework estimates the steering motor internal resistance through Kalman filtering to detect motor faults, and further identifies performance degradation and hard faults using the generalized likelihood ratio of the motor torque signal. For performance degradation faults, a sliding-mode observer reconstructs the fault value and enables motor torque compensation to recover the steering response; for hard faults, the steering function is reconfigured through differential steering, where a sliding-mode controller calculates the required differential steering moment and the wheel longitudinal forces are optimally distributed. Simulation and hardware-in-the-loop tests demonstrate that the proposed strategy effectively maintains steering response, path-tracking accuracy, and yaw stability under different steering motor fault modes.