Output feedback attitude synchronization tracking control for formation flying satellite

An output feedback structured attitude synchronization tracking control law is developed for the attitude synchronization tracking control with external constant disturbance and unobservable angular velocity. Specifically, two low-pass linear filters are firstly designed by using the absolute and relative attitude errors; then an adaptive updating law is also involved to identify the satellite inertia matrix such that no knowledge of the inertia of satellites in formation is required a prior. Moreover, the conditions of the communication topology are proved that if the undirected communication topology is a tree structure and the desired attitude is available only to a single satellite, the global stability is guaranteed for the system. The designed control law needs no explicit differentiation of attitude to synthesize angular velocity-like signals into the desired value, and the integral feedback term led into the control law makes the closed-loop system get better convergence in the presence of unknown (constant) disturbance torques, and further the communication load between satellites and the desired reference is relieved. Simulation results are presented to demonstrate the effectiveness of the control law.