65米射电望远镜副面调整系统姿态精度监测与回零策略

上海天文台65米射电望远镜的副面调整机构为Stewart型并联机器人,为了及时发现该并联机器人因机械磨损或误差累积造成的精度下降问题,使用倾角传感器对并联机器人动平台姿态进行检测,求得动平台姿念均方根误差并将其与设计指标进行比较,从而用户可以判断是否需要进行维修或回零操作.为了提高并联机器人的易维护性,设计了光电传感器回零和磁尺(磁致伸缩位移传感器)回零两种回零方式,分析了两种回零方式以及通过回零操作对光电传感器和磁尺精度进行检测的原理.总结了该并联机器人需要进行回零操作的不同状况,并给出了相应的回零控制策略.实验证明本文提出的回零控制策略是解决并联机器人回零问题的一种有效方法.

Orientation Precision Monitoring and Homing Strategy of the Subreflector Adjusting System for 65 Meters Radio Telescope

The subreflector’s adjusting mechanism of the 65 meters radio telescope in Shanghai observatory is a Stewart parallel robot.In order to find out the problems of this robot’s precision decline in time,caused by mechanical wear or error accumulation,inclinometers are used to measure the orientation of the mobile robot platform.Comparing the RMS (root mean square) error of the measured platform orientation with the expected orientation precision,thereby the user can judge whether maintenance or homing is required.For improving the easy maintenance of the parallel robot,two ways of homing are set up,by using photoelectric sensor and magnetic linearity displacement transducer(MLDT) respectively.The principles of the two ways of homing are analyzed,particularly that of calibrating the precision of the photoelectric sensor and the MLDT by using the homing operation.What’s more,different conditions under which the parallel robot needs homing operation are summarized,and the corresponding homing control strategies are proposed.Test shows that the homing strategy proposed is an effective tool to solve homing problem of the parallel robot.