ZHANG Li-min，AN Qi-chang，YANG Fei

（Changchun Institute of Optics，Fine Mechanics and Physics，Chinese Academy of Sciences，

Changchun 130033，China）

Abstract：Aiming at the problems of measuring comprehensively and exactly the flexibility parameters of the flexural support system for reflect mirror，the parameter identification was investigated and the modal parameter identification theory was introduced in the frequency domain to analyze the flexibility parameters of the flexural support system. Firstly，the spring-mass-dumping modal in series was built to study the flexural support system in certain direction and get the methods approach to the parameter of the free side sub-system by the transfer matrix of the overall system. Then，after the analysis of numerical emulation，the correctness of the research mentioned above was evaluated. At the last，it was tested by use of the special flexural support system，Bipod for instance，for small reflect mirrors. The experimental results indicate that compared with experiment error between researched method and traditional way are smaller than 5%， which indicate that it is rational and accurate，can act as the reference of the measurement and analysis for other flexible system.

Key words：modal parameter identification；transfer function；flexural support；flexibility parameters