挠性空间结构的密集模态特性及影响分析

挠性空间结构周期性构型引起的低频段模态密集问题给振动控制中的控制对象建模、传感器优化配置和控制方案设计等造成困难.本文推导密频结构模态不稳定特性的产生机理,随即证明模态不稳定特性引发模型不确知性,而后基于可控性Gram矩阵的奇异值分析了密集模态的低可控度,并通过分析剩余模态的作用机理,说明模态密集将加剧溢出问题.在分析密集模态特性及影响的同时,给出控制设计中应注意的问题及可能的解决途径,对密频挠性结构在轨振动控制设计具有重要参考价值.

An Analysis on Characteristics and Impacts of Close Modes in Flexible Space Structures

Along with spacecraft growing complex, flexible space structures such as large solar panels and large deployable antenna are often applied. To achieve ideal attitude performance and antenna pointing accuracy, vibration control receives much attention. It is worth noticing that flexible space structures often possess close modes at low frequency, which potentially poses problems for the vibration control system. Characteristics and impacts of close modes must be taken into consideration in object modelling, actuators/sensors placement and controller design. In this paper, the reason for modal instability of close modes is first deduced, followed by the proof of model uncertainty caused by this modal instability. Then, based on the singular values of controllability Grammian, the particularity on the controllability of close modes is analyzed. Moreover, the spillover disturbance is demonstrated to show the impact of close modes further. Based on these characteristics, suggestions for vibration control of structures with close modes are proposed, which offers important reference value to on orbit vibration control of flexible space structures.