基于模态观测器的挠性航天器姿态控制

Sliding Mode Attitude Control for Flexible Spacecraft Based on Modal Observer

针对带有挠性附件航天器的姿态跟踪问题,提出了基于挠性模态观测器的滑模控制律。采用混合坐标法建立挠性航天器动力学模型,构造挠性模态观测器观测挠性模态位移及其变化率。选择一类滑模面,用Lya-punov方法得出基于挠性模态观测器的滑模控制律,并给出了稳定性证明。分别在变速率姿态跟踪,恒速率姿态跟踪和零速率姿态跟踪的情况下进行了仿真。仿真结果显示,与一般的滑模控制律相比,提出的控制律能够有效提高姿态控制的稳态精度,减小挠性模态振动对姿态控制的影响。

To solve the attitude control problem of spacecraft with flexible appendages, sliding mode control law based on modal observer is presented. Hybrid coordinate method is adopted to model the dynamic of flexible appendages, and the modal displacements and their derivatives are observed by the modal observer. A kind of sliding surface is selected to obtain the sliding mode control law based on the observer and the stability proof is given using the Lyapunov stability theory. Simulations are done under variable angular velocity tracking, constant angular velocity tracking and zero angular velocity tracking respectively, and the resuhs show that compared with the conventional sliding mode control law, the control law presented here could improve the steady state control accuracy and diminish the effect of modal vibration on the attitude control.