离焦成像条件下的螺纹牙型角修正方法  

Correction method of thread angle under defocus imaging condition

作　　者：李奎 陈曼龙[1,2] 燕立志 杨帆 余智超[1,2] LI Kui;CHEN Manlong;YAN Lizhi;YANG Fan;YU Zhichao(School of Mechanical Engineering,Shaanxi University of Technology,Hanzhong 723000,China;Shaanxi Key Laboratory of Industrial Automation,Hanzhong 723000,China)

机构地区：[1]陕西理工大学机械工程学院,陕西汉中723000 [2]陕西省工业自动化重点实验室,陕西汉中723000

出　　处：《光学技术》2022年第2期204-209,共6页Optical Technique

基　　金：陕西省教育厅专项科研计划项目(18JK0145)。

摘　　要：针对机器视觉中螺纹参数测量无法实现正确对焦的问题,通过理论与实验相结合的方法研究了离焦成像对螺纹牙型角参数测量的影响。证实了离焦现象对螺纹参数测量会造成不可忽略的误差。并且通过螺纹图像清晰度评价值与离焦量关系的分析,提出了螺纹牙型角误差修正的方法。首先对图像清晰度评价值与离焦量进行标定,然后求取待测图像的清晰度评价值,由评价值得出修正后的离焦量,最后根据离焦量对选定区域的图像边缘长度和面积进行修正,利用修正后的结果求取螺纹牙型角。实验结果表明,对于M20×1.5-6H的螺纹塞规而言,当离焦量小于0.5mm时,经修正后的牙型角相对误差小于0.0425%。Aiming at the problem that the thread parameters can not be focused correctly in machine vision,the influence of defocus imaging on the thread angle parameters are studied by combining theory and experiment.It is proved that defocus phenomenon can cause nonnegligible error in thread parameter measurement.By analyzing the relation between the sharpness evaluation value of thread image and defocus quantity,a method for correcting the error of thread angle is proposed.Firstly,the sharpness evaluation value and defocus quantity of the image are calibrated,then the sharpness evaluation value of the image is calculated,and the defocus quantity is corrected.Finally,the length and area of the image edge of the selected area are corrected according to the defocus quantity,and the thread angle is calculated using the modified results.The experimental results show that the relative error of the modified thread angle is less than 0.0425%when the defocusing quantity is less than 0.5 mm for the screw plug gauge of M20×1.5-6 H.

关 键 词：离焦成像 清晰度评价 牙型角 误差修正 

分 类 号：TP394.1[自动化与计算机技术—计算机应用技术]