Relative orbit and attitude integrated coupled control for formation satellite

The problem of the relative orbit and the attitude coupled control of the formation satellite is studied by using single body fixed low-level continuous thruster and reaction wheels. Actually, the action time of the thruster is much longer for the relative orbit control by a low-level thruster, and the thrust vector cannot point out in any direction at a certain time or during a period of the time interval, thus, the thrust vector depends on the current attitude and its maneuverability of the satellite. In particular, the star camera cannot point out in the sun during formation maneuvering due to the high attitude determination requirement of some formation mission. The formation coupled control is a difficult problem with nonlinear and non-convex attitude dynamics. Then, it is transferred as a nonlinear optimal control problem via direct transcription using the Gauss pseudo-spectral method. Examples demonstrate that the proposed method is effective for the simulated trajectory optimization of a dual-satellite formation initialization.