Adaptive finite time distributed 6-DOF synchronization control for spacecraft formation without velocity measurement

In this paper, the problem of distributed finite time six-degree-of-freedom (6-DOF) synchronization control for spacecraft formation flying (SFF) with the external disturbances and parameter uncertainties is investigated. Firstly, a continuous adaptive finite time distributed control protocol with full state feedback is proposed, which can overcome the chattering problem and reduce the convergence time in the reaching phase. Subsequently, an adaptive sliding mode observer with finite time convergence is designed to estimate the velocity information. Then a new observer-based continuous adaptive finite time distributed control protocol is designed. Rigorous proofs show that these two distributed controllers both can guarantee that the attitude and relative position tracking errors can converge to the origin within finite time rather than the bounded regions around the origins. Finally, the effectiveness of the designed distributed control protocols is demonstrated by simulation results.