Fault tolerant attitude control design for rigid satellite using sliding mode observer technique

In this paper, the problem of fault tolerant attitude control against unknown actuator faults is investigated for the rigid satellite attitude dynamics by using sliding mode observer technique. Firstly, the satellite's dynamic equations and kinematic equations are given to describe the attitude systems of rigid satellite. Then the actuator fault model is introduced to represents the loss of effectiveness fault and stuck fault. To obtain the estimation value of the effects of unknown actuator fault, a nonlinear sliding mode observer is developed and an adaptive fault estimation law is also developed. Based on the estimated fault information, an active fault tolerant attitude controller is designed for the attitude systems of rigid satellite. Meanwhile, the stability of closed-loop attitude control systems is analyzed by using Lyapunov approach. Finally, simulation results are given to demonstrate the effectiveness of the developed fault tolerant control scheme.