Fixed-Time Sliding Mode Tracking Control and Adaptive Actuator Failure Compensation for Dual-Three-Phase Motor Steer-by-Wire System

The steer-by-wire (SbW) system driven by the dual-three-phase permanent magnet synchronous motor (DTPMSM) is attracting increasing attention. However, the parameter uncertainties, external disturbances, and potential actuator malfunctions pose great challenges for steering execution. To achieve precise, rapid, and robust tracking, this paper proposes a novel fault-tolerant tracking scheme incorporating the fixedtime sliding mode control and the adaptive actuator failure compensation. Initially, this paper delineates the configuration of the DT-PMSM driven SbW system, followed by the development of its mathematic model accounting for actuator faults. Then, a non-singular fixed-time sliding mode surface is developed by leveraging the proposed fixed-time stable system with a fast convergence rate. Subsequently, the fixed-time control law and the adaptive compensation law are proposed, which can ensure fixed-time stability under normal conditions and Lyapunov stability under fault conditions respectively. For accurate fault detection and strategy implementation, an event-triggered mechanism based on the cumulative sum (CUSUM) is introduced. Moreover, the fixed-time extended disturbance observer (FEDO) is designed to suppress the lumped disturbances, whose settling time is also bounded and independent of initial states. Simulation and experimental results substantiate the excellent transient and tracking performances of the proposed scheme under both normal and fault conditions.