Adaptive Fault-Tolerant Control for Rigid Spacecraft Attitude System Using Fractional Order Sliding Mode

This paper proposes an adaptive fault-tolerant attitude control method for a faulty rigid spacecraft. The proposed scheme solves a difficult problem of fault-tolerant control (FTC) design in the presence of actuator loss of effectiveness (LOE) fault and bias fault. Firstly, an adaptive sliding mode fault estimation observer is designed for the faulty attitude system of rigid spacecraft to get the estimated value of the actuator faults under the unknown uncertainty and external disturbance. On this basis, an adaptive FTC approach is developed for the rigid spacecraft attitude system in actuator faulty case by combining backstepping control and fractional-order terminal sliding mode (FOTSM) techniques, such that the closed-loop system not only has good robustness to external disturbance, but also has better fault-tolerant capability to unknown actuator faults. Finally, simulation results are presented to demonstrate the effectiveness of the proposed method.