Abstract: The two level coupled tuning system of feed of the large radio telescope(LT) is composed of a Stewart fine tuning platform mounted in the suspended feed cabin and the cable-cabin coarse tuning system. By combining the dynamic equation for the structural nonlinear finite element of a cable system with that for the multibody system of the Stewart platform, the dynamic model of the rigid-flexible coupled two-level kinematic tuning system is constructed, which is an efficient method to analyze the coupled dynamic problem. The response of the cabin to the movement of the Stewart platform is simulated with the application of the model to the LT50m scaled model, and its results are validated by the experiment. The research serves as a foundation for designing the mass ratio of Stewart to cabin to eliminate the effect of the Stewart platform adjustment on the cabin.

Key words: large radio telescope, cable-cabin system, Stewart platform；dynamic coupling