The Study Of Model Reduction For Dynamics Of Flexible Multibody System

In order to dynamics analysis and control system design, it is necessary to build the model of the flexible multibody system. A model with a large number of degrees of freedom ,can cause numerical difficulties ,uncertainties , and high computational casts if used to study the dynamics of a system. The model coordinate of the flexible appendage added to the system is the reason that cause the order of the system too high. Therefore, the most important question of the model reduction is the selection of the component modal coordinate.First, the developing history of the dynamics modeling and model reduction of the flexible multibody system is summarized in detail.Second, for the flexible spacecraft , the linear equation of the flexible multibody system is established, which is based on the component modes.Third , the three methods including inertia! completion, modal cost analysis and inner balanced method are researched respectively and deeply. In the case of the small damping and widely separated natural frequencies, the approximation expression of the modal cost is introduced ,and the system is approximately balanced.At last, according to the typical flexible spacecraft ,the relation of the component model and system model is studied .The number of the appendage model is selected through the modal cost analysis and inner balanced method to build the reduction system. The result showed that the reduction system is same with the original system with MATLAB.