Adaptive Nonsingular Terminal Sliding Mode Control for Attitude Tracking of Spacecraft with Actuator Faults

In this paper, an adaptive nonsingular terminal sliding mode control (ANTSMC) is investigated for attitude tracking of spacecraft with actuator faults. First, a nonsingular fast terminal sliding mode surface is designed to avoid the singularity. Finite-time attitude control is developed using the nonsingular terminal sliding mode technique, which can make the attitude and angular velocity tracking errors converge to zero in finite time in the presence of uncertainties and external disturbances. Second, the total uncertainty is deduced to be bounded. The adaptive laws are incorporated to develop the ANTSMC, removing the restriction on the upper bound of the lumped uncertainty. The finite-time convergence of the closed-loop system with ANTSMC is proved using the Lyapunov stability theory. Finally, the simulation results are presented to demonstrate the performance of the proposed controllers.