Development of a pilot of an Arecibo-type large spherical radio telescope for the square kilometre array

Abstract

An optomechatronics design project for the pilot of an Arecibo-type large spherical radio telescope for the square kilometre array (SKA) is proposed, concentrating on the feed-supporting system with large-span cables. The feed-supporting system consists of two parallel manipulators: the parallel cable manipulator, which provides a large workspace for the trajectory tracking and realizes the coarse tracking control, and the fine-tuning Stewart platform, which connects the parallel cable manipulator to the cabin structure and implements the high-accuracy requirement of tracking. In order to improve the real-time controllability, an approximate kinematics model of the parallel cable manipulator is developed using straight links to approximate the cables based on static equilibrium at low tracking velocity. A control strategy for the feed-supporting system is proposed using the independent control method, and the corresponding tracking accuracy of the coarse control and fine tuning is presented. The simulation results have supported the rationale of this approximate model of the parallel cable manipulator and the feasibility of this mechatronics design project for the SKA.