激光跟踪仪测角误差的现场评价

Field evaluation of laser tracker angle measurement error

激光跟踪仪是基于角度传感和测长技术相结合的球坐标测量系统,其长度测量采用激光干涉测长方法,可直接溯源至激光波长,因此,激光跟踪仪的长度测量精度远高于角度测量精度,相对而言,测角误差就成为评价跟踪仪测量精度的重要指标。为了对现场测量激光跟踪仪的测角误差进行快速有效地评价,采用跟踪仪多站位对空间中测量区域内若干个被测点进行测量,与传统基于角度交汇原理的多站位冗余测量不同,利用各站位所观测的高精度测长值建立误差方程,并通过测长方向的矢量位移对跟踪仪测长误差进行约束,获得被测点三维坐标在跟踪仪水平角和垂直角方向上的改正值,以此来评价激光跟踪仪的测角误差。通过Leica激光跟踪仪AT901-LR进行了多站位测角误差评价实验,在现场测量条件下,跟踪仪水平和垂直方向测角误差约为0.003 mm/m(1σ),符合跟踪仪的测量误差特性。

Laser tracker is a spherical coordinate measuring system based on angle and length measurement technolo- gies. The length measurement uses laser interference method, which can traceable to the laser wavelength directly. So, the tracker length measurement accuracy is much higher than its angle measurement accuracy; comparatively speaking, angle measurement error is an important indicator for evaluating tracker measurement accuracy. In order to evaluate angle measurement error quickly and efficiently, laser tracker is used to measure several measuring points with multi-stations, which is different tYom traditional redundant measurement based on angle intersection. In this paper, an error equation is established using the high-precision length measurement values observed by the laser tracker in multi-stations; then the length measurement error is constrained by the vector displacement in length meas- uring direction; at last, three-dimensional corrected coordinates in the directions of horizontal angle and vertical an- gle are obtained to evaluate the angle measurement error. Field evaluation experiments with multi-station measure- ment were carried out using Leica laser tracker AT901-LR; the angle measurement error is about 0. 003 mm/m（1σ） in the field measurement condition; the result is consistent with the laser tracker error characteristics.