Study of Control Method for Large Telescope with Friction Drive

Currently, friction drive with ultra-low speed and high accuracy is widely used in large astronomical telescopes. However, astronomical telescope is a large inertia load. Slippage and creepage are hardly avoided while the telescope are operating at ultra-low speed and facing variable external disturbances like wind buffeting. This paper describes the control method and software design for the large telescope with friction drive. UMAC-cored high-accuracy servo control system and nonlinear control algorithm are applied. The development platform, system architecture and the relations among all modules, as well as the functionalities are analyzed. The experimental results of LAMOST (The Large Sky Area Multi-object Fiber Spectroscopic Telescope) are demonstrated to show that the performance of the control method and software satisfies the requirements of large telescope.