重心时变的多级混联支撑系统终端精度分析

Terminal Accuracy Analysis of a Multi-level Hybrid Support System Based on Time-varying Barycenter

为保证天文观测的跟踪精度,针对500m口径大型球面射电望远镜(FAST)的多级混联馈源支撑系统因重心实时变化带来的终端馈源接收机位姿误差问题,本文首先构建索并联机构的弹性力学模型,建立馈源舱的重心位置和馈源接收机位姿误差的关系模型.然后,研究馈源舱重心的时变规律.最后,采用Newton-Raphson法迭代确定重心时变引起的馈源接收机位姿误差范围.最大位置误差和姿态误差分别达到120mm和1.40°,无法达到天文观测的精度要求,因此在原型机的设计、抑振控制及精度控制时要充分考虑重心变化的影响.

In the multi-level hybrid feed support system of the Five-hundred-meter Aperture Spherical radio Telescope （FAST）,the cabin＇s time-varying barycenter can cause the terminal feed receiver＇s pose error.In order to ensure the tracking accuracy of astronomical observations,firstly the elastic mechanics model of the cable-driven parallel mechanism is deduced, and the relationship between the cabin＇s barycenter location and the feed receiver＇s pose error is illustrated.Then the change law of the cabin＇s barycenter is studied.Finally,the Newton-Raphson method is adopted to iteratively get the range of the feed receiver＇s pose error caused by the time-varying barycenter.The maximum position and orientation errors are respectively 120mm and 1.40°,which can＇t meet the astronomical observations＇ accuracy requirement.So the cabin-barycenter change should be considered in the prototype design,vibration control and precision control.