摘要
针对机器视觉难以对反射表面进行缺陷检测等问题,本文提出一种基于相位测量偏折术的缺陷检测方法。该方法以LCD屏幕作为结构光源,格雷码图案结合相移图案作为结构光,通过LCD屏幕投射到被测表面,使用单目相机捕捉结构光的反射图案。首先对相机捕捉的图案逐个像素进行解码,获得包裹相位和条纹级数;然后进行相位展开并消除误差,生成绝对相位图像;再使用Canny算子对图像进行边缘检测,将投影区域与非投影区域分割;最后在投影区域内使用Canny算子检测出缺陷的边缘,实现表面缺陷的检测与定位。实验结果表明在环境亮度较低且恒定的条件下,相位测量偏折术可高效检测出反射表面上具有形变特征的缺陷,精度为0.1 mm,基本满足对反射表面上多种缺陷进行高精度、高效率、低成本检测的要求。
Aiming at the problem that machine vision is difficult to detect defects on reflective surfaces,a defect detection method based on phase measuring deflectometry is proposed in this paper.This method uses an LCD screen as a structured light source,Gray code pattern combined with phase shift pattern as structured light,which is projected onto the measured surface through the LCD screen,and monocular camera is used to capture the reflected pattern of the structured light.Firstly,the image captured by the camera is decoded pixel by pixel to obtain the wrapped phase and fringe order.Secondly,the absolute phase image is generated by unwrapping phase and eliminating the error.Thirdly,Canny operator is used to detect the edge of the image to segment the projected region and the unprojected region.Finally,Canny operator is used to detect the edge of defect in the projected region to realize the detection and location of surface defect.The experimental results show that under the condition of low and constant ambient brightness,phase measuring deflectometry can efficiently detect the defects with deformation characteristics on the reflecting surface,with an accuracy of 0.1 mm.It basically meets the requirements of high precision,high efficiency and low cost detection for various defects on the reflected surface.
作者
陶迁
周志峰
吴明晖
王立瑞
TAO Qian;ZHOU Zhi-feng;WU Ming-hui;WANG Li-rui(School of Mechanical and Automotive Engineering, Shanghai University of Engineering Science, Shanghai 201620, China)
出处
《液晶与显示》
CAS
CSCD
北大核心
2020年第12期1315-1322,共8页
Chinese Journal of Liquid Crystals and Displays
基金
上海市科学技术委员会科研基金(No.17511106700)。
关键词
机器视觉
缺陷检测
相位测量偏折术
格雷码
相移
machine vision
defect detection
phase measuring deflectometry
Gray code
phase shift
