Fixed-time fault-tolerant control for virtually coupled train set with actuator faults and saturation

This paper investigates a fixed-time fault-tolerant control problem for the virtually coupled train set subject to the actuator faults, input saturation, external disturbances and parameter uncertainties. A novel fixed-time adaptive sliding mode fault-tolerant control scheme is proposed. By introducing the hyperbolic tangent function, a failure compensation strategy is designed to address the unknown actuator fault without the prior knowledge of fault. Moreover, we estimate the combinations of unknown parameters instead of directly estimating the unknown parameter itself, which significantly saves the computing resources of trains and improves the efficiency. Furthermore, an auxiliary system is introduced to compensate for the influence of input saturation. It guarantees the position and speed tracking errors of each train can converge to the small regions in fixed time in despite of the influence of internal faults and external disturbances, as well as actuator saturation. The proposed control scheme is of great significance to improve the efficiency, safety and reliability of high-speed trains' operation. Finally, simulations are provided to verify the feasibility and effectiveness of the proposed control scheme.