Indexed on: 17 Jul '15Published on: 17 Jul '15Published in: Nonlinear Dynamics
Global attitude stabilization of a rigid spacecraft with unknown actuator delay time is an important problem that has rarely been studied. In this paper, first we investigate a Lyapunov-based controller for attitude regulation of a rigid spacecraft with delayed inputs. Simple conditions for global asymptotical stability are obtained by assuming that the true delay value is unknown, but approximation of its upper bound is available. It is also shown that a proper design of the controller prevents the unwinding phenomenon. Then, we extend the results for the system while taking disturbance effects into account. Based on Lyapunov–Krasovskii methodology, it is proven that the proposed controller can drive the closed-loop trajectories to a small region in the neighborhood of the origin in the presence of external disturbances and model uncertainties. Various numerical simulations are carried out to illustrate the effectiveness of the proposed control system.