应用激光跟踪仪的三坐标测量机几何误差检测方法

Measurement Method of Geometric Error of Coordinate Measuring Machine Using Laser Tracer

几何误差是三坐标测量机的重要误差来源,三坐标测量机几何误差检测方法存在效率低、测量精度不高的问题,严重影响三坐标测量机使用性能的进一步提升。为此,提出了一种应用激光跟踪仪的三坐标测量机几何误差检测与直接分离方法。首先,基于多体系统理论和齐次坐标变换方法,建立三坐标测量机几何误差模型;其次,建立激光跟踪仪测量几何误差的数学模型,以三坐标测量机几何误差特性为约束条件,结合Levenberg-Marquardt方法,实现了几何误差的直接分离。最终,应用该方法在某三坐标测量上进行了几何误差检测试验,并使用激光干涉仪进行了单项定位误差和空间位置误差的检测对比。试验结果表明:该三坐标测量机X、Y和Z轴定位误差分别为-27.06、43.75和36.76μm,X、Y轴垂直度误差为-82.89μrad,是其主要误差来源;预测最大空间误差为74.64μm,位于测量空间的极限区域。辨识结果与激光干涉仪检测结果相比,X、Y和Z轴定位误差最大相差7.43μm,体对角线预测定位误差最大相差10.51μm;与其他跟踪测量方法相比,X和Y轴空间位置误差与激光干涉仪检测结果相差最小为5.3μm,验证了该方法的有效性。该方法可在2 h内实现三坐标测量机17项几何误差的检测,具有快速和高精度的优点,在三坐标测量机和数控机床精度检测领域有较大的应用前景。

Geometric error is an important error source of coordinate measuring machine(CMM).The geometric error measurement methods currently used have the problems of low efficiency and low accuracy,which seriously deteriorate the further improvement of the performance of CMM.Hence,a novel geometric error measurement and direct separation method of CMM using laser tracer was proposed.Firstly,the geometric error model was established based on the multi-body system theorem and homogeneous coordinate transformations.Furthermore,the mathematical model of geometric error measurement using laser tracer was formulated.And the geometric errors were directly separated based on the constraints of geometric error characteristics combining with the Levenberg-Marquardt method.Finally,the experiment of geometric error measurement of a CMM using a laser tracer and comparison experiments of single axis positioning error and volumetric positioning error were carried out.The results showed that the positioning errors of X,Y and Z axis are-27.06,43.75 and 36.76μm,respectively,and the squareness error between X and Y axis was-82.89μrad,which were the main error sources.The maximum volumetric error predicted of CMM was 74.64μm,which was located in the limit area of the measurement volume.The identification results of geometric errors compared with the results measured by laser interferometer showed that,the maximum difference of three-axis positioning errors was 7.43μm and the maximum difference of body diagonal positioning errors predicted was 10.51μm.Compared with other laser tracking geometric error measurement method,X and Y axis volumetric positioning errors measured by this proposed method were the closest to the results measured by laser interferometer with the maximum difference of5.3μm which verified the effectiveness of this method.In addition,the 17 geometric errors of CMM could be measured within 2 hours by the method,which is of high speed and accuracy,and has a large application in the field of accuracy measurement of CMM and CNC machine tool.