Deep-Coupled Sliding Mode Disturbance Observer-Based Composite Attitude Control for Flexible Communication Spacecrafts

Multifrequency flexible vibration generated from solar arrays and deployable antennas has become the dominant disturbance source for communication spacecrafts with high precision, high stability, and fast-response attitude control requirements. Thereby, focusing on the accurate and rapid rejection of flexible vibration disturbance, a deep-coupled sliding mode disturbance observer (DO)-based composite attitude control scheme is proposed in this article for flexible communication spacecrafts. First, the dynamic of flexible vibration disturbance has been fully excavated and described by a recessive model, overcoming the conservativeness of derivative-bounded assumption in traditional methods. Second, a novel deep-coupled sliding mode DO with finite-time convergence and adaptive parameter estimation capabilities is proposed to estimate the flexible vibration disturbance, where the disturbance model has been fully utilized. Then, based on the output of deep-coupled sliding mode DO, a composite attitude control law is proposed by combining a finite-time backstepping control. Unified stability analysis has been conducted by combining the observer dynamic and attitude control dynamic. Finally, numerical simulation and experiment verification are respectively carried out to show the performances of the proposed method.