Disturbance observer based finite-time coordinated attitude tracking control for spacecraft on SO(3)

To solve the problem of attitude synchronization control for spacecraft formation flying (SFF) suffering from external disturbances under a directed communication topology, a sliding mode disturbance observer (SMDO) based on the finite-time control strategy is developed to observe the time-varying external disturbance via estimating the upper bound of its first derivative. Meanwhile, the rotation matrix is employed to describe the attitude of SFF for the purpose of the avoidance of singularity and unwinding phenomenon. As for the attitude synchronization and the tracking control architecture, a sliding mode surface (SMS) is given such that the control objective can be achieved. The effectiveness and the validity of the proposed method are elaborated via theoretical analysis and numerical simulations.