Finite-time adaptive fault-tolerant attitude control for rigid spacecraft

This paper presents a novel finite-time adaptive fault-tolerant sliding mode spacecraft attitude control method, which could provide a rapid, accurate, and reliable attitude control for spacecraft rejecting external disturbances, uncertainties and actuator failures. Firstly, the dynamics and kinematics of the spacecraft in the presence of unknown disturbances and uncertainties are formulated. It is assumed that external disturbances and uncertainties are limited to unknown upper bounds (total uncertainties). The gain fault and the deviation fault are considered into the actuator failures. The error dynamics of the spacecraft attitude control is established including the total uncertainties. Secondly, a significant adaptive parameter, which is the estimation of the upper bound of total uncertainties, and a corresponding update law are designed. The adaptive update law, which contains a negative feedback term, could guarantee the convergence of the estimation. Then, based on the adaptive update law, a novel finite-time adaptive fault-tolerant attitude control method is derived under the framework of sliding mode control theory. Since the total uncertainties of spacecraft are compensated by the adaptive update law, the proposed control method can achieve higher control accuracy in the presence of actuator failures and disturbances. For the proposed control law, a certain term of control formulation is specially designed which can guarantee the finite-time stability. Finally, the Lyapunov function is established to prove the spacecraft can be stabilized in the finite time. Numerical simulations are performed to illustrate the effectiveness of the proposed control scheme.