针对刚体航天器姿态机动过程中存在的控制饱和与外部干扰问题,提出一类基于新型非奇异饱和终端滑模面的有限时间控制器设计方法。该控制方案不仅保证姿态机动过程的快速性,而且避免了传统的终端滑模面所带来的奇异性问题。此外,本文建议的控制器不仅显式考虑执行器输出力矩的饱和幅值要求,使航天器在饱和幅值的约束下完成姿态控制任务,而且控制器的设计对外部干扰的上界没有任何要求,也无需作任何小角度的假设。进一步的稳定性分析表明,通过引入新型非奇异饱和终端滑模,该控制器使得闭环系统能够快速收敛到滑模面的微小邻域内,继而收敛到平衡点的微小邻域内,并且系统对外部干扰具有较强的鲁棒性。数值仿真校验了该控制器在姿态机动过程中的性能。
A novel nonsingular saturated terminal sliding mode (NSTSM) based control law is investigated for a rigid spacecraft, in which the actuator control input saturation and even external disturbances are explicitly considered simultaneously. Specifically, in this proposed control scheme, the fast convergence of spacecraft attitude maneuvering is achieved, and also singularity can be avoided in comparison with traditional terminal sliding mode, the spacecraft is allowed to perform the given operations within the saturation magnitude. It is important to note that the results of this paper are derived with respect to magnitude saturation and under the condition of no additional restrictions on upper bound of disturbances, and need not to make any small-angle assumption. The stability analysis further shows that the controller ensures the closed-loop system to converge to the small neighborhood of the sliding surface fast and then to the small neighborhood of the equilibrium point, and has better robustness to external disturbances. The attitude maneuvering performance of the controller is evaluated by using a numerical example.