Analysis of a Supporting System with a Stewart Platform for Telescope Secondary Mirror

A virtual prototype model of a new type of 6-PSS parallel structure was established.The stiffness, the precision, and the layout of the drive in the 6-PSS parallel structure, which was used in the supporting system of the secondary mirror in our 2-meter level astronomical telescope, were better than those in a 6-SPS parallel structure.There are seven parameters in the model to define the structure.The paper focuses on the analysis of the relation between stick force and elevation angle, which needs to be particularly and carefully considered in applications to telescopes.We also derived a method for setting the parameters, which allows the states of stick force to change rather weakly and limits the maximum stick force for the range of the elevation angle of 0° to 90°.