管件内部截面形状和尺寸的非接触测量系统

Measure system for internal cross section shape and diameter of pipe

针对目前异形管件内部形状尺寸非接触测量光源成本高、加工精度难以保证等问题,在深入研究柱透镜光学性能的基础上,设计并实现了由线激光器和柱透镜组成的近封闭激光线作为光源、用CMOS相机采集测量对象的内部截面图像的光电测量装置。运用五方向边界跟踪虫提取经过自适应阈值化处理的内部截面图像的边界。通过近似曲率梯度场确定圆弧与直线段的切点,根据切点对边界点分组,计算直线段长度,运用最小二乘法计算圆弧半径和圆心位置。实验结果表明,本系统的测量结果与千分尺直接测量的结果相比,绝对误差最小达到0.01 mm,相对误差最小达到0.01%。该装置在保证良好采集管件内部横截面图像、较高的测量精度的同时,避免了对测量对象的影响,在降低成本的同时,实现了真正意义上的非接触测量。

The cost of measure system of abnormal hollow parts＇ inner diameter is high, and the manufacture accuracy of light system is demanding. An automatic measure platform was established to decrease the cost with high accuracy guaranteed.A laser beam radiator composed of laser line and cylindrical lens is taken as the light to get the hollow part＇s inner images,which are captured by the CMOS camera. The images were preprocessed by self-adapted threshold, edges of which were traced with five-direction trace bugs. The points of tangency were determined according to the gradient of the edges＇ approximate curvature. The points on the edges were classified into two groups, then the length of lines is got. The radius and the center of the arcs were computed using least square method. Experimental results show that, the measure platform can measure the inner dimension without contact. The minimum absolute error reaches 0. 01 mm, and the minimum relative error gets to 0. 01 percent.