Integrated fault estimation and fault tolerant attitude control for rigid spacecraft with multiple actuator faults and saturation

This study proposes an integrated fault estimation (FE) and fault-tolerant control design for a rigid spacecraft attitude system with inertia uncertainties, external disturbances, input saturation, and different type multiple actuator faults. A barrier function is first introduced to eliminate the effects of inertia uncertainties and disturbances in the design of the sliding mode FE observer. By using the non-singular fast terminal sliding mode control technology, a finite-time fault-tolerant attitude stabilisation controller and a finite-time fault-tolerant attitude tracking controller are designed to guarantee that the closed-loop attitude system has a good fault-tolerant performance under actuator faults. Furthermore, when considering actuator saturation, an auxiliary system is utilised to compensate for the saturation. The stability of the closed-loop system is analysed by Lyapunov theory. Finally, the effectiveness of the proposed control approach is demonstrated via simulation results.