Attitude tracking and trajectory planning for underactuated spacecraft

This paper provides some new results for the problem of attitude tracking control and on-line feasible trajectory generation for a symmetric rigid spacecraft with two controls. First, we deduce the attitude tracking models, and design the tracking control law based on the backstepping method. Second, we derive the necessary and sufficient condition of feasible trajectory according to the models characteristics, and utilize the notion of differential flatness to propose a simple way for designing the trajectory in the flat output space. Third, the control law and the feasible trajectory are simulated according to the different attitude tracking task. Both the theoretical and numerical results illustrate the validity of the control strategy in this paper.