Attitude Tracking of Rigid Spacecraft with Bounded Input

Attitude control is essential for spacecraft to accomplish various tasks, and the attitude tracking is one of the most important attitude control tasks. In this paper the attitude tracking of a rigid spacecraft with bounded input is examined. At the same time, the unknown external disturbances are finite, but their boundaries are unknown. In order to make sure the attitude tracking errors converge to zero, the nonlinear system model and problem formulation are obtained using quaternion method. Meanwhile a novel adaptive-robust-sliding mode control algorithm is designed, which can be applied in spacecraft systems with large parametric uncertainty or even with unknown inertial matrix. At last simulation results can illustrate the effectiveness of the control law.