Distributed composite state observer-based cooperative control for spacecraft swarm

This paper proposes a distributed composite state observer-based cooperative control scheme for multiple spacecraft with consideration of external disturbances. The nonlinear relative motion dynamics of multiple spacecraft is established in a rotating local-vertical local-horizontal (LVLH) reference frame attached to a virtual spacecraft. Based on the undirected topology, a novel distributed composite state observer is developed for each follower spacecraft only using the position level information of its neighbors, such that the states and total disturbances of both the leader spacecraft dynamical model and the consistency error system can be estimated. Then, a composite controller is put forward in terms of the outputs of the developed composite state observer, which not only enables to overcome the external disturbances but also achieve spacecraft consistent collaborative control or formation flying. The convergence and stability of the distributed composite state observer and the closed-loop control system are verified by the Lyapunov theory. Finally, the effectiveness of the presented cooperative control strategy is proved by two illustrative numerical simulations.