基于变结构/输入成形的航天器振动抑制方法

针对挠性航天器大角度姿态机动的振动抑制问题,提出了一种基于输出反馈变结构控制和输入成形振动抑制方法相结合的主动振动控制策略.首先,采用拉格朗日方法建立中心刚体上带有弹性附件的航天器的动力学模型.然后,在基于非线性和低阶模态的动力学模型基础上,考虑挠性结构模态不可测的情况,为了避免设计状态观测器及其引入的误差,在输出反馈变结构控制的基础上,给出了滑模存在条件以及仅利用输出信息的变结构控制器设计方法,使系统的状态轨迹达到滑动平面,并保证闭环系统渐近稳定;在此基础上,应用输入成形方法设计成形控制器来抑制该系统的振动,使得航天器星体姿态和挠性附件的振动同时得到了有效的控制.该成形控制器的设计仅需闭环系统的振动频率和阻尼.将该方法应用于单轴挠性航天器的大角度rest-to-rest(静止到静止)姿态机动控制进行了仿真研究,结果表明,方法可行有效.

Flexible spacecraft attitude maneuvering and vibration damping using variable structure control in put shaping

A generalized scheme based on the output feedback variable structure control(OFVSC) and input shaping(IS) technique has been proposed for the rotational maneuver and vibration suppression of an orbiting spacecraft with flexible appendages.The proposed control design process is design of the attitude controller followed by the design of a flexible vibration attenuator.The attitude controller using only the attitude and angular rate information for the flexible spacecraft consists of a linear feedback term and a discontinuous feedback term.By combining the linear term with the discontinuous term,very good disturbance rejection and robustness can be achieved with a lower control effort that would be required from either control when used independently.The linear gain and the discontinuous gain are designed so that the sliding surface exists and is globally reachable.With this attitude controller in place,the dynamics of the closed-loop system is studied and any harmonics in the response are eliminated using input shaping technique,which requires information about the natural frequency and damping of the closed-loop system.This information is used to modify the input such that the flexible modes are not excited.The proposed control strategy has been implemented on a flexible spacecraft,which is a hub with symmetric cantilever flexible beam appendages and can undergo a single axis rotation.The results have proven the potential of this approach to contrvol flexible spacecraft.