Accuracy design of the Stewart manipulator of the Five-hundred-meter Aperture Spherical radio Telescope

A Stewart manipulator is used in the Five-hundred-meter Aperture Spherical radio Telescope to ensure the position and orientation accuracy of the feed receivers. Due to the weight limit, the feed cabin has a low stiffness, which highly affects the control accuracy of the Stewart manipulator based on the control conditions. The main purpose of this article is to present an effective accuracy design method of the Stewart manipulator of the Five-hundred-meter Aperture Spherical radio Telescope. First, error modeling of the Stewart manipulator with the structural deformation is set up, which can indicate the influence on the control error caused by the structural deformation in real-time control. Second, by analyzing the accuracy factors of the Stewart manipulator, the end-effector error limit caused by the structural deformation is obtained. Third, an error distribution method based on the maximum coefficient method is proposed, which guides the structural design of the feed cabin. Fourth, a semi-physical simulation model of the feed cabin is set up to simulate the control accuracy of the feed cabin, and the experiment results show that the control error of the feed cabin is within root mean square 4.8 mm. Finally, the feed cabin is effectively used in the Five-hundred-meter Aperture Spherical radio Telescope within its root mean square 10-mm accuracy requirement.