Fixed-Time Coordination Control for Spacecraft Formation Flying via NFFTSM and Sliding Mode Disturbance Observer

This paper presents a distributed fixed-time control protocol for spacecraft formation flying with the sliding mode disturbance observer. Firstly, the dynamics of spacecraft formation is established. The formation has one virtual leader spacecraft and n follower spacecraft, and the information flow among the formation is described by a directed graph. Secondly, a sliding mode disturbance observer is developed to estimate the external disturbances, which can guarantee the estimation errors converge to zero in finite time. Thirdly, a non-singular fixed-time fast terminal sliding mode cooperative controller is designed to ensure that each spacecraft will track their desirable positions and velocities in fixed time. The stability of the closed-loop system is proved through Lyapunov method. Finally, simulation results demonstrate the effectiveness of the proposed control method.