O形密封圈尺寸视觉精密测量技术

针对现有O形密封圈尺寸测量方法的局限性,设计基于主动视觉的精密检测方法,并对快速自动调焦、亚像素边缘检测、边缘点拟合技术进行了研究。将快速自动调焦过程分为3个阶段,使用大步长和方差函数,结合灰度切割对比度增强与中值滤波,完成粗调焦;使用小步长和Tenengrad函数,完成细调焦;采用Brenner函数和微步距完成高灵敏度调焦.用Zernike矩算法对边缘点进行亚像素定位,并采用面积最小误差法拟合边缘点,求取O形密封圈的内径、外径.实验结果表明:本文方法经过16步搜索,在15 s内可自动完成调焦;与传统方法相比,通过亚像素提取,能将内外径测量结果达到微米级,满足O形密封圈测量需求. 

Vision-Based Precision Measurement Technology for O-Ring Seal Size

To overcome the disadvantages in existing methods for detecting the size of O-ring seals, a precise measurement method based on active vision was proposed, and the technologies such as automatic quick-focusing, sub-pixel edge detection, and edge fitting were studied. The procedure of automatic quick-focusing was divided into three phases. The rough focusing was implemented through image contrast enhancement in gray scale, mid-value filter, large step and variance function calculation; the fine focusing was realized using small step and Tenengrad function; and the high sensitivity focusing was realized using micro step and Brenner function. In addition, edge points were located with sub-pixel accuracy using the Zernike moment algorithm. The inner and outer diameters of the O-ring seal were measured with the edge fitted by the minimum area error method. The experimental results show that the proposed method can realize an automatic focusing within 15 s in 16 search steps. Compared with the traditional methods, the proposed method, by sub-pixel detection, can reach a accuracy of 1 μm in the outer and inner diameter measurement of O-ring seals, which satisfies the measurement requirements of stability and accuracy for O-ring seals.