激光跟踪仪的高精度预准直方法和精度分析

High Precision Pre-Alignment Method Based on Laser Tracker

  • 摘要: 新型粒子加速器对关键元件的准直测量精度要求越来越高,而现有测量仪器受自身技术发展的限制,难以在短时间内显著提高其单站测量精度,由此提出一种基于激光跟踪仪的三维测边网平差的预准直测量方法。通过布设多个测站,将定位点和测站点的坐标均作为未知参数进行平差解算,得到较高精度的定位点坐标。此外,通过比较分析不同测站数目下各定位点的解算精度,得到局部最优测站数。实验结果表明,三维测边网平差解算的定位点精度远高于同等观测条件下三维边角网平差解算的定位点精度。当采用22个测站时,各定位点的空间点位中误差的均值为8.9 μm。根据4个定位点均要获得10 μm以内的定位精度需求,综合考虑定位精度和工作效率两方面因素,判断布设12个测站能达到此要求。所提方法对实际工作中高精度的预准直测量和设备的安装定位具有一定的工程应用价值。

     

    Abstract:
      Objectives  Higher accuracy is needed for the alignment and installation of key components in new generation particle accelerators. However, the existing measuring instruments are limited by the technological development, it is difficult to significantly improve the measurement accuracy in a short time.
      Methods  In this paper, we proposed a novel pre-alignment method based on 3D trilateration network adjustment of laser trackers. Firstly, we established multiple survey stations surrounding the component which needs to be pre-aligned. Then, we utilized only distance observations between station points and location points to establish 3D trilateration network. Finally, we regarded all coordinates of both station points and location points as unknown parameters, and adopted a 3D free trilateration network adjustment.
      Results  Experimental results show that the root mean squared error (RMSE) of location points calculated by 3D triangulateration are three times higher than that calculated by 3D trilateration. In addition, the average RMSE of location points can reach the highest precision as 8.9 μm by establishing 22 survey stations. Because the precision is no-more-than 10 μm by establishing 12 survey stations, we consider 12 as the quantity of locally optimal survey stations.
      Conclusions  This method can provide crucial engineering values for the practical work during the high-precision alignment and installation of devices.

     

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