Optimal attitude control of an accompanying satellite rotating around the space station

This paper mainly deals with the optimal control of an accompanying satellite (AS) rotating around the space station (SS). The concept of AS around the SS is introduced. Both the AS and the SS are modeled as rigid bodies with the reference coordinate frames described for the AS pointing to the SS according to different missions. Then the paper designs an optimal control law with the full set of nonlinear equations of motion derived by using unit quaternion. These equations are solved numerically using direct transcription method to obtain optimal solution for the underactuated satellite. The analytical and simulation results show that the proposed control law is effective in the case of failed actuators.