柔性航天器高精度隔振与定向研究

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。

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

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 RMS 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.