基于远心镜头的活塞外轮廓机器视觉测量技术研究

Research on Machine Vision Measurement Technology of Piston Profile Based on Telecentric Lens

为提高活塞裙部轮廓尺寸的检测效率,提出一种基于远心镜头的活塞外轮廓视觉检测方案。采用矩方法提取活塞裙部特征点,通过特征点定位测量高度位置,利用反正切函数拟合指定高度上活塞裙部边缘在水平方向的灰度变化,借助标准塞规确定真实边缘位置与边缘灰度变化曲线的关系,从而实现图像边缘亚像素级定位。搭建了由远心镜头、平行光源、精密伺服转台、面阵相机等构成的活塞裙部轮廓视觉测量实验平台,实验结果显示,图像测量的标准偏差0.0078mm,置信系数为2时,测量的极限偏差为0.0156mm。

In order to improve the detection efficiency of piston skirt profile size,a visual inspection scheme of piston profile based on telecentric lens is proposed.The piston skirt feature points are extracted by the moment method,the height position is measured by feature point positioning,the grayscale variation of the piston skirt edge in the horizontal direction at the specified height is fitted by the inverse tangent function,and the relationship between the real edge position and the edge grayscale variation curve is determined by the standard plug gauge,so as to realize the sub-pixel level positioning of the image edge.An experimental platform for visual measurement of piston skirt profile consisting of telecentric lens,parallel light source,precision servo turntable,and surface array camera is built.The experimental results show that the standard deviation of image measurement is 0.0078 mm,and the limit deviation of measurement is 0.0156 mm when the confidence factor is 2.