航天器姿态系统饱和抗干扰控制方法的研究

In the field of spacecraft attitude control, two problems are often encountered: input saturation and anti-disturbances. To deal with them, lots of scholars have proposed their solutions, whereas few are able to deal with these two problems simultaneously due to their own disadvantages, i.e., the form of the designed controllers are too complicated, or the range of the parameters that can be chosen are limited, or the convergence of the quaternion cannot be guaranteed, etc. The goal of the study is to further investigate these problems by utilizing nonlinear system's theory and invariant area analysis, and includes three aspects. Firstly, for a double integrator system, we will try to design controllers that are simple and loose on choosing control parameters, and in the meanwhile we will provide the rigorous proof of the closed-loop stability. The purpose to study on a double integrator system lies in that it is the simplified form of an attitude system in the case of small angles. Secondly, in view of the importance of input-to-state stability in the saturated and anti-disturbance control of nonlinear attitude system, we will study the states’ behavior under disturbances, and try to design switched controllers with robustness that can ensure the input-to-state stability of the nonlinear attitude system. Finally, we will conduct a systematic research on the anti-disturbance control of nonlinear attitude system with input saturation. We will design saturated controllers that enjoy more freedom of selecting controller parameters while providing rigorous proof of closed-loop stability.

控制力矩饱和与抗外界干扰时在航天器姿态控制问题中具有广泛的应用背景。许多学者曾提出过解决方案，但能同时处理这两方面问题的成果并不多，且存在控制器形式复杂、参数要求严格和不能保证四元数收敛等缺点。本文即对该问题展开深入研究，试图利用非线性系统理论,结合不变区域分析等手段,设计出饱和抗干扰的姿态控制器,具体包括三方面的内容。首先，针对姿态系统线性化后的二阶积分系统，试图设计出形式简单、参数要求宽松的饱和PID控制器，并提供闭环稳定性的严格证明。其次，考虑到姿态系统的输入-状态稳定性在饱和抗干扰问题中的重要作用，将对非线性姿态系统在存在干扰下的状态行为进行深入研究，并设计出能满足输入-状态稳定的鲁棒姿态切换控制器。再次，对非线性姿态系统的饱和抗干扰问题展开较为系统的研究，力图克服已有文献中不能保证四元数收敛的缺点，设计出参数要求宽松、抗干扰能力强的饱和控制器，并提供闭环系统稳定性的完整证明。

控制输入饱和问题属于控制领域的难题。本课题对航天器姿态控制当中的饱和控制问题进行了较为深入的研究。主要针对二阶积分系统中的饱和控制器设计、非线性姿态系统中的输入-状态稳定性和非线性姿态系统的饱和抗干扰控制这三方面开展研究，并在各方面均取得了一定的研究成果。针对二阶积分系统，提出了基于干扰快速闭环辨识和补偿的控制方案，并将该方法推广到含有挠性和液体晃动的复杂航天器当中，具有较强的工程适用价值。针对非线性姿态系统采用连续PD控制律不能获得输入-状态稳定特性的问题，提出了采用具有时滞特性的混杂型PD控制律，并严格证明了闭环系统相对于干扰的输入-状态稳定性。基于该输入-状态稳定的结果，提出了两种新的鲁棒饱和控制器。在非线性姿态系统的饱和抗干扰控制方面，研究了不同干扰形式下饱和PD控制的姿态系统的闭环状态行为；提出了基于四元数分区的切换型类饱和控制器，较好的解决了机动性与状态约束的矛盾；提出了基于自适应的月球着陆器六自由度控制器，较好的消除了推力和质量不确定性对悬停的影响。