线结构光三维传感器扫描方向标定方法  

A Scanning Direction Calibration Method of Line-Structured Light Three-Dimensional Sensors

作　　者：刘昌文 段发阶[1] 李杰 徐毅 邢少颖 Liu Changwen;Duan Fajie;Li Jie;Xu Yi;Xing Shaoying(State Key Laboratory of Precision Measuring Technology&Instruments,Tianjin University,Tianjin 300072,China;AECC Sichuan Gas Turbine Research Establishment,Chengdu 611730,Sichuan,China)

机构地区：[1]天津大学精密测试技术及仪器国家重点实验室,天津300072 [2]中国航发四川燃气涡轮研究院,四川成都611730

出　　处：《中国激光》2023年第5期50-56,共7页Chinese Journal of Lasers

基　　金：国家重点研发计划(2020YFB2010800);国家自然科学基金(61905175,61971307);青年人才托举工程(2021QN⁃RC001);国防科技重点实验室基金(6142212210304);霍英东教育基金会资助项目(171055);广东省重点研发计划(2020B0404030001);中国航发四川燃气涡轮研究院外委课题(WDZC2021-3-4)。

摘　　要：线结构光三维传感器需要结合扫描机构才能对物体进行三维重构,在使用前需要对扫描方向进行标定。由于各个标定图像的清晰度不同,传统标定方法会多次引入噪声,降低了标定精度。为了减小由图像清晰度不同多次引入的噪声,本文提出了基于联合估计的扫描方向标定方法。在标定过程中,需要使用位移台将平面靶标移动一个固定的距离,使每个拍摄位置处的靶标相对相机坐标系的旋转矩阵相同,同时平移向量的变化由位移台的运动步长约束。通过对旋转矩阵和平移向量增加约束,将平面靶标上的二维特征点拓展为三维特征点;联合所有标定图像进行统一的单应性估计,减小了由图像清晰度不同多次引入的噪声。通过测量量块尺寸进行了验证实验,实验结果表明:所提方法的测量误差相比传统方法减小了约30%,而且所提方法具有更好的重复性。所提方法实现了线结构光三维传感器扫描方向的高精度标定,减小了传感器三维重构的误差。Objective In a visual measurement system,the scanning mechanism is used to move the vision sensors or the measured object to expand the measurement range,which is known as translation scanning.The measurement range of a single image,particularly for a linestructured light threedimensional(3D)sensor,is only the light stripe formed by the intersection of the light plane and object.To achieve a 3D reconstruction of the measured object,a scanning mechanism must scan the entire surface of the light plane.In practical applications,linestructured light 3D sensors and translation scanning mechanisms are used in combination to measure flat objects and in defect detection,quality control,geometric dimension measurement,positioning,and other applications.However,before use,it is necessary to unify the coordinate systems of the scanning mechanism and sensor,that is,to calibrate the translation direction of the scanning mechanism.In the traditional calibration method,the checkerboard plane target is fixed,sensor is moved along the scanning direction,and camera captures target images.Subsequently,the extrinsic camera parameters corresponding to each image are estimated separately,and the 3D coordinates of the same feature point on each target image are calculated in the camera coordinate system.Finally,the 3D coordinates of the same feature point are fitted with a straight line,and the straight line’s direction vector is the scanning direction.Because of the different sharpness of the target images captured at different positions,the corresponding camera extrinsic parameters contain different noises for each image separately,introducing noise several times when calculating the 3D coordinates of feature points and then reducing the calibration accuracy.Methods First,the study analyzed and verified the disadvantages of the traditional calibration method,which introduces noise several times.In the verification experiment,the target was only translated by the highprecision stage;the orientation of the plane target relative to th

关 键 词：机器视觉 扫描方向标定 联合单应性估计 噪声分析 线结构光传感器 

分 类 号：TP29[自动化与计算机技术—检测技术与自动化装置] TH741[自动化与计算机技术—控制科学与工程]