Stiffness Study of a Hexapod Telescope Platform

This paper presents our study on the structure of a hexapod platform used as a coplanar mount for a radio interferometer array. We have surveyed the hexapod platform using the photogrammetry method to measure its upper surface deformation under various pointing positions of the hexapod. We have also measured the strain distribution at the high strain areas of the platform structure. The results provide important information to verify the structural design of the platform, and a direct monitoring on the platform structural integrity. These measurements are compared with the finite-element analysis (FEA) that takes into account the gravity loading and the interaction loading between the platform and the hexapod. This study concludes that the interaction loading between the platform and the hexapod actuators is the dominant factor affecting the platform deformation.