Robust time optimal controller design for rigid spacecraft under input saturation

This paper presents a robust adaptive controller dealing with time optimal attitude control problem for rigid spacecraft under input saturation while taking inertia uncertainties, external disturbances and actuator configuration misalignments into consideration. In order to improve the robust performance merely using open-loop time optimal control, a closed-loop attitude tracking strategy is proposed, which means designing a controller to guide system states to follow the prior optimization results. The optimization procedure is implemented by solving the nonlinear programming problem to which the original problem is transformed with the aid of collocation method. The closed-loop tracking controller design is achieved by utilizing sliding mode and adaptive control methods to provide control system with strong robustness. Simulation results show that the presented controller has good control performance under multiple constraints mentioned above.