On Dynamic Performance Of The Cable-cabin System Of The Large Radio Telescope

The suspended cable-cabin system of the Large Radio Telescope belongs to under-constrained parallel mechanism. The positioning accuracy of its cable-cabin system is difficult to control.Based on LT5m suspended cable-cabin system,a research of dynamic performance is carried out for improving the performance and the positioning accuracy of the system.In this thesis, with cable described as catenary shape, a nonlinear mathematical model of the cable-cabin structure is established, and the cables' lengths and forces are calculated out through an optimal strategy on the distribution of the driving forces when the focus cabin moves along its trajectory. Thus the unlooped control of movement of the cabin is realized by adjusting the lengths of the cables coordinately.Dynamic model of the cable-cabin system is derived by finite element method (FEM).This is a basis of analyzing the dynamic performance of the cable-cabin system.Based on the analysis of statics,an analysis of dynamic performance about LT5m suspended cable-cabin system is carried out,including modal analysis,harmonic response analysis,spectrum analysis.Natural frequencies and vibration modes of six-cable system is obtained.The results of dynamic analysis is in line with the law of vibration and is corresponding to the natural frequencies and vibration modes of the system.And the modal of nine-cable system is established.Two configurations,six-cable system and nine-cable system,are based on LT5m suspended cable-cabin structure, and their dynamic responses are compared.This demonstrates that dynamic performance of nine-cable system is better than that of six-cable system.It can restrain the vibration of suspended cable-cabin system effectively.The research work in this thesis provides the basis for further improving the dynamic performance of the suspended cable-cabin system of the Large Radio Telescope.It has certain guiding significance in engineering applications.