Research On Dynamic Analysis And Active Vibration Control Of Deployable Space Truss Structure

In recent years, the space truss structures have a large number of applications in the aerospace industry because of its characteristics of large packaging ratio, light weight and superior stiffness and strength。When working in an environment with zero gravity,its low-frequency and large-amplitude vibration will easily be excited. Because of small damping, the vibration will last for a long time, which will not only endanger other related equipments'function, even cause system failure for internal energy dissipation. The problem of vibration suppression for large deployable truss in space now becomes one of the international hot issues for the researchers.This paper works on the active vibration control of the deployable space truss structures from four aspects, such as actuators design, modeling methods of truss and analysis, active vibration suppression methods and active control experiments.By analyzing the operating principle of the piezoelectric ceramic actuators, experiments of its static and dynamic responses of output displacement are done and the active control struts which can replace the original struts of the truss are designed. In order to overcome the shortcoming of small output displacement of PZT actuators, a new kind of shape memory alloy actuator is raised and the influence factors of its performances is studied by experiments.The results of active vibration control are inseparably related with the dynamic characteristics of the controlled object. So the dynamic analysis of the truss is studied before the active vibration control. The modeling programs of truss based on space bar elements and the three-dimensional frame elements are written separately. The natural frequencies and mode shapes of the truss are calculated in order to explore the influence factors of vibration characteristics of the truss as well as to prepare for the simulation of active vibration control. The model strain energy at every struts location is computed to select the suitable locations for active control struts.Quadratic optimal control and modal space are used to control the vibration of the truss by simulation. The influence of different locations of the active control strut is considered. Taking the maximum of diagonal element of the modal assurance criterion matrix as target function, the number and locations of the sensors are optimized by the Multiple Island Genetic Algorithm.The practical vibration characteristic of the truss is studied by hammering method, and the modal parameters are distinguished by LMS PolyMAX method. The results are compared to the results of the theoretical analysis before. Active vibration control experiments of the truss are carried out by the control method of proportional feedback control.