Adaptive Tracking Control for Spacecraft Formation Flying System via Modified Fast Integral Terminal Sliding Mode Surface

In this paper, the fast integral terminal sliding mode control for spacecraft formation flying system is concerned subjected to external disturbances and parametric uncertainties. First, a novel modified fast integral terminal sliding mode control law is designed, which contains the advantages of fast terminal sliding mode. Then, for estimating the external disturbances in the system, the control law based on the reduced-order disturbance observer is proposed which not only reduce the order of the observer but also guarantee the tracking errors converge in finite time. Further, to identify the unknown parameters accurately, by introducing an adaptive parametric updating law, the adaptive fast integral terminal sliding mode control law is proposed, which has better robustness against external disturbances and parameter uncertainties simultaneously. Finally, the effectiveness of the proposed control laws is demonstrated by the simulation results.