Attitude-constrained feedback control for spacecraft reorientation under actuator saturation and compound disturbance

The attitude-constrained reorientation maneuver problem in the presence of actuator saturation, parametric uncertainty, and external disturbance is investigated. An empirical-trial-free parameter-selection-method for the existence-conditions of the repulsive-potential-function is proposed, which enhances the universality of the potential- function-based controller and is able to avoid unnecessary detour during the maneuver process. In addition, an auxiliary system driven by the difference between the untreated command torque and the upper bound of the actuator torque is presented. Using the auxiliary system, the designed backstepping controller is able to guarantee the system stability without actuator saturation violation. In order to achieve real-time compensation of the compound disturbance consisting of parametric uncertainty and external disturbance, an extended state observer with finite time convergence is put forward. Thus, the ESO-based backstepping controller obtains a better performance on robustness and accuracy. Finally, simulations are carried out to illustrate the effectiveness of the proposed control scheme.