系统参数标定过程对多边坐标测量系统测量不确定度的影响

Influence of system parameters calibration process on measurement uncertainty of multilateral coordinate measurement system

坐标测量结果的不确定度评定是多边坐标测量系统待解决的关键问题之一。实际应用中,系统通常需标定系统参数后再进行测量,因此系统参数标定过程会对测量结果产生重要影响,但目前还缺乏相关研究。为了对其准确评定,建立了多边坐标测量模型,分析了测量不确定度的空间分布特性,重点研究了系统参数标定的影响并评定了整体测量不确定度。结果表明,目标点的x坐标、y坐标、z坐标测量不确定度分别优于0.004 0 mm、0.003 8 mm、0.005 3 mm,且测量不确定度的空间分布呈现径向、轴向不同的特点。进行了坐标测量精度验证实验,结果表明,两目标点间测距量不确定度优于0.005 3 mm,各组En值均小于1,验证了评定结果的准确性。研究了各不确定度分量对总体测量不确定度的影响,其不确定性主要来源是反射镜的光学中心偏差以及系统参数标定不确定度,表明系统参数标定过程对多边坐标测量系统测量不确定度的影响不容忽视。

Uncertainty evaluation of coordinate measurement result is one of the key problems in multilateral coordinate measurement system. In the practical application, it is necessary to calibrate system parameters before measurement. Therefore, the calibration process of system parameters have an important impact on measurement results. However, there is still lack of relevant research. To evaluate it accurately, a model of multilateral coordinate measurement is formulated. The spatial distribution characteristics of the measurement uncertainty are analyzed. The uncertainty of system parameters calibration is mainly studied and the overall uncertainty of measurement is evaluated. Results show that the measurement uncertainty of x coordinate, y coordinate and z coordinate of the target point is better than 0.004 0 mm, 0.003 8 mm and 0.005 3 mm, respectively. In addition, the spatial distribution of measurement uncertainty presents different characteristics of radial and axial directions. The accuracy of coordinate measurement is also evaluated by experiments. Results show that the measurement uncertainty of distance between two target points is better than 0.005 3 mm. En value of each experiment is all less than 1, which verifies the accuracy of the measurement uncertainty evaluation result. The influence of each uncertainty component on the overall measurement uncertainty is studied. The main sources of uncertainty are optical center deviation of reflector and uncertainty of system parameter calibration, which indicate that the influence of system parameter calibration process on the measurement uncertainty of multilateral coordinate measurement system cannot be ignored.