Spacecraft fault-tolerant control using adaptive non-singular fast terminal sliding mode

Finite-time convergence control strategies based on adaptive non-singular fast terminal sliding mode are proposed for spacecraft attitude tracking subject to external disturbances, inertia uncertainties, control saturation and actuator faults. A finite-time fault-tolerant attitude tracking controller meeting the multi-constraints is developed by introducing a non-singular fast terminal sliding mode with finite-time convergence and singularities avoidance attributes. It is further shown that the controller is independent from inertia uncertainties and bound of external disturbances with parameter adaptations. In addition, the controller designed in this paper explicitly considers the actuator output torque saturation amplitude requirements, which makes the spacecraft complete the given operations within the saturation magnitude and without the need for on-line fault estimate. The Lyapunov stability analysis shows that the designed controller can guarantee the fast convergence of the closed-loop system and has a good fault tolerant performance on control saturation and actuator faults under the multi-constraints on external disturbances, inertia uncertainties, control saturation and actuator faults. Numerical simulation has verified the good performance of the controller in the attitude tracking control.