柔性航天器高精度隔振与定向研究

Research on High Accuracy Pointing of the Flexible Spacecraft with Stewart Platform

随着大型航天器柔性越来越大,结构越加复杂,导致低频柔性模态密集,但同时需要极高的定向精度及姿态稳定度,这就对航天器姿态控制系统提出了更高的要求。本文采用拉格朗日法建立了柔性航天器姿态轨道耦合动力学模型,并设计了大角度机动航天器的姿态控制器。Lyapunov定理给出闭环系统的稳定性,在0.03Nm均方根的白噪声扰动下,大角度机动姿态角误差小于0.02°,均方根误差0.003°,为了抑制姿态抖振,设计了复合控制器,采用Stewart平台对敏感载荷局部高精度主动隔振和定向,局部控制后敏感载荷的定向误差小于0.0001°,均方根误差0.000036°。鲁棒Η∞控制器对Stewart平台主动镇定时,姿态抖振小于0.000002°,均方根误差小于0.0000008°,姿态稳定度优于0.00001°/s。

In this paper, the coupled dynamics model of the flexible spacecraft is derived by using Lagrange method, and attitude controller is designed for a large angle maneuvering spacecraft. The stability of closed loop is given by Lyapunov theorem. The error of attitude angle is less than 0.02° and the RiMS error is 0.003° at white noise random disturbance of RMS of 0.03Nm. Then, Stewart platform is used for fine active isolation and pointing of partial sensitive payloads. To suppress jitter, a composite controller is designed. The pointing error is less than 0.0001 ° with 0.000036°of RMS, for the measurement noise with 0. 000036° of RMS. Finally, Stewart platform using robust H controller is used to stabilize the partial sensitive payload. The attitude jitter is less than 0. 000002° with 0. 0000008°of RMS and the attitude stability is better than 0.00001°/s.