平面度坐标测量的不确定度计算

目前的坐标测量只是给出平面度最小二乘检验的结果,并没有给出检验结果的不确定度.根据平面度最小二乘检验的基本原理和ISO/TS 14253-2给出的不确定度传递公式,提出了一种平面度坐标测量的不确定度的计算方法.该方法的特点是将平面方程的系数看作一个随机向量,通过计算该随机向量的均值和协方差矩阵来确定平面方程和平面度的检验结果及其不确定度.这不仅保证了平面度检验结果的完整性,而且符合新一代产品几何规范(GPS)标准的要求,从而可以提高工件检验的准确性.实验结果表明,根据平面度最小二乘检验的结果及其不确定度,可以根据ISO 14253-1给出的判定原则定量地判定平面是否合格.

Uncertainty Calculation of Flatness in Three-dimensional Measurements

The least-square method is commonly employed to verify the flatness in actual three-dimensional measurement processes,but the uncertainty of the verification results is usually not given by the coordinate measuring machines.According to basic principles of flatness least-square verification and the uncertainty propagation formula given by ISO/TS 14253-2,a calculation method for the uncertainty of flatness least-square verification was proposed.By this method,coefficients of the plane equation were regarded as a statistical vector,so that the plane equation,the results of flatness verification and the uncertainty of the results can be obtained after the expected values and covariance matrix of vector were determined.The method assured the integrity of the verification results,and accorded with requirements of new generation of GPS standards,which can improve the veracity of verification.Experimental results indicate that in conformity to the results of flatness least-square verification and the uncertainty,the plane can be accepted or rejected quantitatively in accordance with the decision rules given by ISO 14253-1.