大尺寸球形件的光笔式视觉测量系统设计

Design of light-pen vision measurement system for large-scale spherical parts

为实现大尺寸球形零件的三维形貌、球径和球度误差等参数的测量,设计了光笔式视觉测量系统,系统主要由高分辨率摄像机、光笔和配套的图像处理软件组成。首先介绍了系统的测量原理,然后依次研究了其中的关键技术:光笔的结构设计和基于近景摄影测量的光笔标定方法,利用单应性矩阵建立光笔坐标系和摄像机坐标系之间转换关系的方法。基于光栅尺的精度评价实验表明,在2000 mm×1500 mm视场范围内,相对测量精度优于0.05 mm/m。选取大尺寸金属球为实验对象,提取了球面若干点的三维坐标,生成拟合球并计算出球度误差为2.068 mm。

In order to measure the three-dimensional shape,spherical diameter and sphericity error of the large-size spherical parts,a light-pen vision measurement system is designed.The system is mainly composed of high-resolution camera,light pen and supporting image processing software.Firstly,this paper introduces the measurement principle of the system,and then gives the key technologies in turn:the structural design of the light pen and the light pen calibration method based on close-range photogrammetry,and the method of establishing the conversion relationship between the light-pen coordinate system and the camera coordinate system by using the homography matrix.The accuracy evaluation experiment based on grating ruler shows that the relative measurement accuracy is better than 0.05 mm/m in 2000 mm×1500 mm field of view.Taking the large-size metal ball as the measured object,the three-dimensional coordinates of multiple points on the balll surface are extracted to generate the fitting ball,and then the sphericity error is calculated to be 2.068 mm.