Novel non-singular saturated terminal sliding mode based attitude controller for spacecraft

A novel nonsingular saturated terminal sliding mode (NSTSM) based control law is investigated for a rigid spacecraft, in which the actuator control input saturation and even external disturbances are explicitly considered simultaneously. Specifically, in this proposed control scheme, the fast convergence of spacecraft attitude maneuvering is achieved, and also singularity can be avoided in comparison with traditional terminal sliding mode, the spacecraft is allowed to perform the given operations within the saturation magnitude. It is important to note that the results of this paper are derived with respect to magnitude saturation and under the condition of no additional restrictions on upper bound of disturbances, and need not to make any small-angle assumption. The stability analysis further shows that the controller ensures the closed-loop system to converge to the small neighborhood of the sliding surface fast and then to the small neighborhood of the equilibrium point, and has better robustness to external disturbances. The attitude maneuvering performance of the controller is evaluated by using a numerical example. ©, 2015, China Spaceflight Society. All right reserved.