四面体三坐标测量机精度分析

Accuracy Analysis of Tetrahedron CMM

并联式三坐标测量机具有测量范围大和精度高的特点。针对这些特点，介绍了一种四面体坐标测量机，可对机床或空间某一点位置进行测量。由于机构的几何误差以及各级伸缩杆之间的不可避免的间隙所带来的误差使得测量机存在一定的测量误差。文中针对伸缩杆杆长误差建立了测量机的测量误差模型，并通过MATLAB软件对测量机测量空间进行误差仿真分析，得到了测量机在机床工作空间的误差缩放规律。通过计算分析得出杆长误差及被测点初始位置误差对测量机测量误差的影响仅在0．2％～1．5％之间，满足测量要求。

Parallel three dimensional( 3D) coordinate measuring machine( CMM) has characteristics of a large measurement range and high accuracy. A tetrahedron CMM was described which can measure the position of a point in space or machine tool by aimed at these characteristics. There were some measurement errors existed in the CMM due to the geometric errors and the error of inevitable gaps of Telescopic rod at all levels. A measurement error model of the CMM was established by aimed at the error of Telescopic rod length,and through MATLAB software,the measurement errors of CMM space were analyzed with simulation so as to obtain error telescopic law of workspace of machine tool in the CMM. By analysis with calculation,it is obtained that the error of Telescopic rod length and measured initial position errors which impacted on the measuring machine error are only between 0. 2% ~ 1. 5%,and meet the measurement requirements.