基于双平行平面相机模型的钢板尺寸视觉测量  

Visual metrology for steel plate sizes based on two-parallel-plane camera model

作　　者：刘昶[1] 韦飞云 孙维广[1] 

机构地区：[1]沈阳理工大学信息科学与工程学院,辽宁沈阳110159

出　　处：《光学精密工程》2016年第4期714-725,共12页Optics and Precision Engineering

基　　金：国家留学基金资助项目(No.201308210280);沈阳理工大学计算机应用重点学科开放基金资助项目(No.4771004kkfx10)

摘　　要：提出基于双平行平面相机模型的视觉测量方法,用于测量生产线上运动钢板的尺寸。该方法采用数据驱动的方式计算像点在标定平面上投影点的世界坐标;采用k近邻(k-NN)方法生成目标在标定平面上的无畸变投影图像,并建立投影图像与世界坐标系的直接关联。提出了双平行平面模型下相机光心位置标定算法,利用线结构光进行板材厚度测量;在无畸变的投影图像上利用钢板边缘间的平行和垂直性进行钢板边缘特征提取,通过边缘直线的世界坐标方程求取长宽尺寸。最后,给出了针对大尺寸钢板测量的多相机测量系统框架。提出的方法为单目视觉测量方法,相比于其他方法具有现场安装简单和标定工作量小的特点。通过图像分辨率为640×480的相机对尺寸为80mm×50mm×15mm的标准铝块进行了测量,结果显示:厚度测量误差为0.1mm,长度和宽度的误差在0.2mm以内。实际应用中测量精度远高于加工精度,能够满足产品计量的要求。A visual metrological method based on a two-parallel-plane camera model is proposed for the measurement of the sizes of moving steel plates on production lines.This method uses a data driven mode to calculate the world coordinates of any image point＇s corresponding projective point on the calibration plane.Ak Near Neighbour（k-NN）algorithm is presented to generate the distortion free projective image on the calibration plane from the original image and to build a direct connection between the image and the world coordinate system.An optical center localization algorithm is also proposed.The metrological method uses line structured light to realize the thickness measurement.Then,it extracts plate＇s edge lines from the distortion free projective image by using their parallel or perpendicular properties and calculates the size of the plate from the edge lines＇ equations in the world coordinate system.Finally,a framework of large scale steel plate size measurement system is given.The abovemethod is a monocular visual metrology.As comparing to other methods,the method is characterized by simple mounting and smaller calibration process.Experiments results show that if a camera with an image resolution of 640×480is used to measure a standard 80mm×50mm×15mm aluminum cuboid via the method,the thickness error is 0.1mm,and the length and width errors are both less than 0.2mm.When the method is applied to real steel plate measurement,the measurement accuracy is higher than manufacture accuracy,which shows that it satisfies the demands of product measurement.

关 键 词：单目视觉 双平面相机模型 钢板 尺寸测量 视觉测量 标定 

分 类 号：TB92[一般工业技术—计量学] TP391[机械工程—测试计量技术及仪器]