带有输入非线性的挠性航天器姿态机动变结构控制

Variable Structure Control for Flexible Spacecraft with Input Nonlinearities During Attitude Maneuver

针对挠性航天器反作用飞轮输入力矩受限情况下的姿态机动问题,提出了一种仅利用输出信息的变结构输出反馈控制方法。在基于非线性和低阶模态的动力学模型基础上,给出了滑模存在条件以及变结构输出反馈控制器设计的方法,并保证闭环系统渐近稳定;另外,为了避免确定不确定性和外干扰界函数上限的困难,又给出了一种自适应变结构输出反馈控制器的设计方法,并基于Lyapunov方法分析了滑动模态的存在性及稳定性。最后,将本文提出的两种控制方法应用于三轴稳定挠性航天器的姿态机动控制,并进行数值仿真研究。仿真结果表明:在反作用飞轮的控制受限条件下,完成姿态机动的同时,使得挠性附件的振动幅值远远小于0.001,有效地抑制挠性附件的振动。

This paper proposes a robust control algorithm for stabilization of a three-stabilized flexible spacecraft in the presence of model uncertainty, external disturbances and control input nonlinearities. This control algorithm is based on variable structure output feedback control design technique, and explicitly accounts for the control input nonlinearities in the stability analysis. The proposed variable structure output feedback controller ensures the global reaching condition of the sliding mode of the spacecraft dynamics system. An attractive feature of the control method is that the structure of the controller is independent of the elastic mode dynamics of the spacecraft, since in practice the measurement of flexible modes is not easy or feasible. It is also shown that an adaptive version of the proposed controller is achieved through releasing the limitation of knowing the bounds of the uncertainties and perturbations in advance. Numerical simulations show that the precise attitude control can be accomplished using the derived controller for both cases with and without adaptive control and the amplitude of the vibration mode is more less than 0.001.