FAST望远镜馈源舱精度分析研究

Accuracy Analysis on Focus Cabin of FAST

500 m口径球面射电望远镜(Five-hundred meter aperture spherical radio telescope,FAST)馈源舱主要用于实现馈源的精调定位,馈源舱的精度控制机构即其内部的Stewart平台,根据控制方案可将馈源舱的精度分析研究简化为该Stewart平台的精度分析研究。根据馈源舱实际工况及控制方案,提出三类馈源舱定位精度主要影响因素,基于索驱动控制误差分析及舱索耦合情况,分析得到为避免舱索耦合而形成的馈源舱控制残差;考虑馈源舱的低刚度性,基于Stewart平台控制方案及结构变形分析参数,采用蒙特卡洛与区间分析方法得到结构变形造成的馈源舱定位误差;分析馈源舱实际测量手段得到测量误差,最终得到三类影响因素下馈源舱定位精度综合评估值。通过建立半物理仿真模型,使用仿真软件模拟实际工况及舱索耦合特性,以实际的馈源舱内机构为试验对象,试验验证了馈源舱精度分析的准确性,并为馈源舱后续调试及应用提供了必要的控制参数和参考。

Focus cabin is used for precise positioning of feeds of the five-hundred meter aperture spherical radio telescope（FAST）. According to the control scheme, Stewart platform in the focus cabin is the adjusting mechanism to realize precise positioning of the feeds. Therefore, the accuracy analysis of the focus cabin can be simplified to the accuracy analysis of the Stewart platform. Three kinds influence factors of feeds positioning is proposed based on the real work situation and control scheme of the focus cabin. By analyzing the control accuracy of the six-cable driven parallel robot and the coupling of the focus cabin and the cables, residual control error of the focus cabin is obtained. Considering the low stiffness of the Stewart platform and its structure deformation analysis, positioning accuracy of the focus cabin is studied by using Monte Carlo and interval analysis method based on the control scheme of the Stewart platform. Meanwhile, positioning error of the focus cabin caused by measurement error is given. Therefore, the comprehensive positioning accuracy evaluation value of the focus cabin can be obtained. Setting up a semi-physical simulation model by using the actual focus cabin and a simulation software to simulate actual working conditions and the coupling characteristics of the cables and the focus cabin, experiment results on the semi physical simulation model verify the positioning accuracy of the focus cabin, and provide necessary reference and debugging parameters of the focus cabin in the real work.