A finite-time adaptive robust control for a spacecraft attitude control considering actuator fault and saturation with reduced steady-state error

This paper addresses the problem of attitude control of a spacecraft in the presence of model uncertainty, external disturbance, actuator fault and saturation. By introducing a novel form of integral backstepping control, a finite-time fault tolerant control is designed to obtain satisfactory performance, rapid convergence of the system states, reduced steady-state error and high robustness. Guaranteeing finite-time convergence of the attitude trajectory is a significant feature of the proposed control law that is critical in fault tolerant systems. Since the upper bound of the system uncertainty and disturbance is quite difficult to obtain, an adaptation mechanism is presented under which there is no need to know this upper bound. Not only finite-time convergence of the attitude trajectory is proved using the Lyapunov analysis, but also the actuator saturation and fault are taken into account while designing the controller. Simulation results verify the effectiveness and performance of the presented approach.