基于结构光的大锻件尺寸测量中光条纹中心线提取方法

大型锻件温度高,测量条件恶劣、误差较大,精确的尺寸测量可有效减少加工余量并提高材料的利用率.以高温锻件图像采集方法为基础,双目视觉结合结构光法可用于大型锻件尺寸在线测量.为消除干扰光线对在线测量锻件尺寸的影响,提出通过对单幅锻件结构光图像处理提取结构光条纹中心线的方法.该方法利用结构光条纹在截面上近似高斯分布的特点,首先根据设定阈值在行方向上搜索,并确定结构光条纹及干扰光线的起始位置;其后从起始位置开始沿光条纹在设定范围内搜索,并判断光条纹截面是否近似符合高斯分布以去除干扰光线;最后以结构光条纹起始位置为起点上下搜索,并计算结构光条纹的亚像素中心.实验结果表明:该方法具有计算简单、实现快速、稳定性好的特点,可用于大型锻件尺寸测量中结构光条纹中心线的提取.

A method for extracting center-lines of structured light stripes in process of dimension measurement of large forgings

It is difficult to measure the dimension of hot large forging accurately in forging process because of the high temperature and poor measuring conditions.Accurate dimension measurement of hot part is very important to improve productivity and reduce scraps during hot forming process.Based on the image acquiring method of hot forgings,binocular structured light system is used to measure the dimension of hot large forgings on-line.Thus,the center-lines of structured light-stripes should be extracted by eliminating other kinds of structured light reflected by hot large forging.A method for extracting the center-lines of structured light-stripes from the single image of hot large forging is proposed.According to a certain threshold,the initial locations of structured light stripes and other kinds of light stripes are determined along a line in the row direction.The cross section of structured light stripe usually obeys the Gaussian distribution,so other kinds of light stripes can be eliminated by searching along the light stripes.Once the start points of light stripes are located in the image,the subpixel centers of structured light stripes can be calculated by searching along the light stripes.Experimental results show that this method is convenient and stable,and can efficiently extract the center-lines of structured light stripes which are projected on the surface of hot large forgings.