精密跟踪型望远镜适配的快速星图匹配  

Rapid star pattern matching for precisely tracking telescopes

作　　者：刘德龙 杨文波[1] 柳鸣 康喆[1] 李振伟[1] LIU Delong;YANG Wenbo;LIU Ming;KANG Zhe;LI Zhenwei(Changchun Observatory,National Astronomical Observatories,Chinese Academy of Sciences,Changchun 130117,China)

机构地区：[1]中国科学院国家天文台长春人造卫星观测站,吉林长春130117

出　　处：《光学精密工程》2022年第22期2952-2961,共10页Optics and Precision Engineering

基　　金：国家自然科学基金项目资助(No.12003052)。

摘　　要：空间目标的精密定轨需要高精度的天文定位技术,而星图匹配是天文定位的基础。本文针对精密跟踪型望远镜提出一种快速星图匹配算法,它包含优化三角形匹配和序列图像修正两部分。论文主要叙述了该算法原理、流程与实现,并对其速度与精度等方面进行了研究。首先,利用编码器轴系定位划取指向天区的星表数据,经筛选和归算列为导航星表。接着,应用降维查表的方法加速三角形匹配并通过理想坐标底片常数之间的关系校验得出首帧匹配结果。然后,修正算法结合后续各帧中望远镜指向的变化量计算导航星的理想坐标,并应用上一帧的底片常数,匹配观测星和导航星。最后,对底片常数计算得出的导航星和目标定位结果进行统计对比。经实验,计算39组星对时采用快速三角形匹配可以将时间缩短至近1/300;对后续图像(每帧含大约100组匹配星对)使用序列图像修正算法,均可以在0.04 s以内完成匹配;采用快速星图匹配算法获取的匹配星对用于对中高轨激光星定位,其平均误差在0.5″左右。由此可见,快速星图匹配算法充分满足精密跟踪型望远镜天文定位精度高、速度快的要求。Star pattern matching is critical when using high-precision astronomical positioning technique,which,in turn,is required for the precise determination of space objects’orbits.This paper proposes a rapid star-pattern-matching method for precisely tracking telescopes,including its principles,program flow and implementation.First,the catalog of pointed sky region was filtered out with the shafting positioning from the encoder;then,after selection and reduction,the stars in the area were compiled into a navigation stars list.After which,the optimized triangle matching method,based on dimension reduction and table look-up methods,was employed in the first frame,where the relation between plate constants verifies the success of matching.The changes of the telescope pointing were considered to calculate the standard coordinates of navigation stars,and the observed stars were matched through the last plate constants.Finally,the coordinates of navigation stars calculated were compared by the plate constants with their reduced values from the catalog,and the position of one space object was calculated through celestial positioning.Experimental results indicated that 39 star pairs could be matched by applying the optimized triangle matching proposed,however,with only approximately 1/300 of the time taken compared to the conventional method.When calculating the following sequential frames(approximately 100 star pairs per-frame),the matching could be finished in less than 0.04 s.The matched star pairs obtained by the rapid star pattern matching algorithm were used to locate an MEO laser satellite with an average error of approximately 0.5″.As a result,the method proposed fully satisfies the requirements of high accuracy and speed in astronomical positioning for precisely tracking telescopes.

关 键 词：星图匹配 天文定位 三角形匹配 图像序列 底片常数 

分 类 号：P123.2[天文地球—天体测量] P123.3[天文地球—天文学]