大尺寸工件螺孔的机器视觉测量方法研究

Study on Machine Vision Measurement Method for Large-Size Workpiece Screw Hole

基于3C产品外壳工件螺纹圆孔加工时通常采用角点定位的特点,利用线阵相机采集子图像的连续性,提出基于直线特征和圆特征定位的螺纹圆孔位置尺寸测量方法。基于拟合法改进的Hough直线定位方法和基于乘同余法改进Hough变换圆形检测方法,实现3C外壳工件图像边缘定位及螺纹圆孔的圆心坐标提取及直径尺寸测量;基于图像的连续性,采用子图像逐一检测,相邻子图像起始像素累加的方式,实现大尺寸图像螺纹圆孔尺寸全局检测。上述方法最终实现大尺寸3C外壳工件螺纹圆孔的位置尺寸测量精度为±0.2220mm和孔径大小测量±0.0904mm,单工件检测耗时为33.737s。

Based on the characteristic of corner positioning commonly used in the machining of threaded circular holes in 3C product shell workpieces,a method for measuring the position and size of threaded circular holes based on linear and circular feature positioning is proposed by utilizing the continuity of sub images captured by a linear array camera.The improved Hough linear localization method based on the fitting method and improved Hough transform circular detection method based on the multiplicative congruence method were used to achieve edge localization of 3C housing workpiece images and extraction of circular coordinates and diameter dimension measurement of threaded circular holes.Based on the continuity of the image,the sub images were detected one by one and the starting pixels of adjacent sub images are accumulated to achieve the global detection of threaded round hole size in large size images.The above method ultimately achieves a measurement accuracy of±0.2220mm for the position and size of the threaded circular hole on large-sized 3C shell workpieces,and±0.0904mm for the aperture size.The detection time for a single workpiece is 33.737s.