Super-twisting Sliding Mode Observer Based Finite-Time Attitude Control of Combined Spacecraft

A novel finite-time controller integrated with disturbance observer is proposed for a combined spacecraft in the presence of inertia uncertainty and external disturbance. As a stepping-stone, a super-twisting sliding mode disturbance observer(STDO) is designed firstly such that the reconstruction of lumped disturbances is accomplished in finite time and the observer error is convergence. Then, with the reconstructed information, a finite-time controller synthesized with the backstepping method, and command filter is used to avoid the too cumbersome analytic derivation, then the closed-loop system/state is proved to be finite-time stable. Numerical simulation results for the combined spacecraft show good performances, which validate the effectiveness and feasibility of the proposed scheme.