空间绕飞任务中航天器姿态跟踪的鲁棒控制

研究了空间绕飞任务中从航天器对主航天器进行观测时的姿态跟踪控制问题，提出了综合考虑挠性、外部扰动和参数不确定性等因素的输入饱和鲁棒控制器设计方法。根据主、从航天器的质心相对运动信息，解算出了从航天器的期望跟踪姿态。为保证从航天器跟踪期望姿态时控制器的有界性和强鲁棒性，将文献中已有的一种一阶滑模姿态调节控制器推广到了姿态跟踪的情况。进一步，为消除一阶滑模控制的高频抖振问题，将姿态跟踪问题转化成了标准的二阶滑模控制问题，提出了一种连续的二阶滑模姿态跟踪控制器。仿真结果表明，本文算法能有效实现绕飞过程中的姿态跟踪，同时具有强鲁棒性。

Robust control of spacecraft attitude tracking for space fly-around mission

The problem of the attitude tracking control for space fly-around mission, when the slave spacecraft is desired to observe the main one, is investigated, and a method of robust controller design, associated with such factors as flexible vibration, external disturbances, and parametric uncertainties, subject to control input saturation, is presented. According to the relative motion information of the mass centers of both spacecraft, the desired attitude to be tracked by the slave is calculated. To guarantee the boundedness and strong  robustness of the controller when the slave tracks the desired attitude, the extension of a first-order-sliding mode controller for attitude regulation given in existing literatures to the case of attitude tracking is attempted. Further, to eliminate the high-frequency chattering brought by the first-order sliding mode controller, the attitude tracking problem is transformed to that of standard second-order sliding-mode control, then a continuous and second-order sliding-mode control based attitude tracking controller is proposed. Simulation results show that the algorithm in the paper can achieve the goal of attitude tracking during the fly-around stage effectively, and has strong robustness.