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新一代空间望远镜、空间激光通信平台及其他敏感载荷要求超静力学环境,传统被动减振无法满足要求,主动振动控制是一种有效的方法,Stewart平台主被动混合隔振被广泛研究。本文分析了立方Stewart隔振器6个主动杆之间的耦合特性,建立了单个主动杆的刚弹耦合动力学模型,并在模态空间中去掉刚体模态。考虑建模不确定性及传感器噪声,利用不含刚体模态的单杆动力学模型,进行多目标Η∞和μ综合控制器设计,对于低频指向控制信号进行保持,而对高频扰动进行抑制。而后对控制器进行鲁棒稳定性测试和分析,并对控制器进行了模型降阶,最后用μ降阶控制器对标称系统进行时域仿真,并与 PI 控制器比较。结果指出μ控制器达到了低频指向信号保持和高频扰动抑制的指标要求。
The new generation of space telescopes, space laser communication platforms and other sensitive loads require an ultra-static environment. The traditional passive vibration reduction can not meet the requirements. Active vibration control is an effective method. The active and passive vibration isolation of the Stewart platform has been widely studied. In this paper, the coupling characteristics of the six active rods of the cubic Stewart vibration isolator are analyzed. The rigid-elastic coupling dynamics model of the single active rod is established and the rigid mode is removed in the modal space. Considering modeling uncertainty and sensor noise, a multi-objective H∞ and μ integrated controller is designed by using a single-rod dynamic model without rigid body modalities, and the low-frequency directional control signal is maintained while the high-frequency disturbance is suppressed . Then the robust stability test and analysis of the controller are carried out, and the controller is modeled and reduced. Finally, the μ-order controller is used to simulate the nominal system in time domain and compared with the PI controller. The results show that the μ controller achieves the target requirements of low-frequency directional signal hold and high-frequency disturbance rejection.