在线测量刀具图像调焦特性的镜头对比研究
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摘要
光学系统是在线高精度视觉测量系统的重要模块,其中远心镜头的引入导致对焦不准、系统复杂度和成本大大提高等问题。文章以实验室搭建的视觉测量系统为平台,采用平行背光源,分别用远心镜头和普通镜头对数控铣刀进行了直径测量。根据清晰度比率、灵敏度、局部极值因子等评价指标对两类镜头环境下的Tenengrad函数特性进行对比分析。结果显示,非远心镜头在灵敏度、分辨率和鲁棒性更占优势,高达35%左右,而远心镜头具有更好的曲线性,超出30%左右。考虑到该在线测量系统应用于复杂工业环境中,应选择分辨率、灵敏度和鲁棒性均占优势,且成本更低的非远心镜头。
The optical system is an important module of the online high-precision visual measurement system,in which the introduction of telecentric lens leads to problems such as inaccurate focusing,increased system complexity and greatly increased cost. In this paper,the visual measurement system built in the laboratory is introduced as a platform,and the diameter of the NC milling cutter is measured by using the parallel backlight. According to the evaluation indexes such as definition ratio,sensitivity and local extremum factor,the Tenengrad function characteristics of two kinds of lens environment are compared and analyzed. The results show that telecentric lens has the advantages of sensitivity,resolution and robustness,which is as high as 35%,while the telecentric lens has better curve,which is more than 30%. Considering that the online measurement system is applied in complex industrial environment,the non-telecentric lens with the advantages of high resolution,sensitivity and robustness and low cost is selected.
The optical system is an important module of the online high-precision visual measurement system,in which the introduction of telecentric lens leads to problems such as inaccurate focusing,increased system complexity and greatly increased cost. In this paper,the visual measurement system built in the laboratory is introduced as a platform,and the diameter of the NC milling cutter is measured by using the parallel backlight. According to the evaluation indexes such as definition ratio,sensitivity and local extremum factor,the Tenengrad function characteristics of two kinds of lens environment are compared and analyzed. The results show that telecentric lens has the advantages of sensitivity,resolution and robustness,which is as high as 35%,while the telecentric lens has better curve,which is more than 30%. Considering that the online measurement system is applied in complex industrial environment,the non-telecentric lens with the advantages of high resolution,sensitivity and robustness and low cost is selected.
引文
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[13]蒋昀赟.基于一种新的调焦函数的工作台实时距离自动检测系统[EB/OL].http://www.paper.edu.cn,2014.
[14]祁晓玲,赵霞霞,靳伍银.基于机器视觉的轴类零件几何尺寸测量[J].组合机床与自动化加工技术,2013(1):65-67.
[2]潘兵,俞立平,吴大方.使用双远心镜头的高精度二维数字图像相关测量系统[J].光学学报,2013,33(4):97-107.
[3]屈玉福,浦昭邦,赵慧洁,等.调焦评价函数灵敏度的影响因素分析[J].光学学报,2005,25(7):902-906.
[4]何博侠,张志胜,徐孙浩,等.大尺寸机械零件的机器视觉高精度测量方法[J].中国机械工程,2009,20(1):5-10.
[5]洪裕珍,任国强,孙健.离焦模糊图像清晰度评价函数的分析与改进[J].光学精密工程,2014,22(12):3401-3408.
[6]金雪,马卫红.图像调焦过程的清晰度评价函数研究[J].光学仪器,2012,34(1):59-64.
[7]Chen C Y,Hwang R C,Chen Y J.A passive auto-focus camera control system[J].Applied Soft Computing,2010,10(1):296-303.
[8]Hong Y Z,Ren G Q,Sun J.Analysis and improvement on sharpness evaluation function of defocused image[J].Guangxue Jingmi Gongcheng/optics&Precision Engineering,2014,22(12):3401-3408.
[9]谢权.镜头像差对图像画质影响的解析与对策[J].西安文理学院学报:自然科学版,2013,16(3):125-128.
[10]Alobayde M A,Abrahem S A.The Effect of Geometrical Dimensions on the Image Position of the Thin Gravitational Lens[J].Annals of Biomedical Engineering,2010,29(12):1064-1073.
[11]王平江,陈德军,巫孟良,等.一种复合的自动对焦方法在影像测量仪中的应用[J].中国机械工程,2007,18(21):2555-2560.
[12]刘焕牢,师汉民,李斌.数控机床定位误差的高精度测量及补偿技术[J].组合机床与自动化加工技术,2005(1):40-41.
[13]蒋昀赟.基于一种新的调焦函数的工作台实时距离自动检测系统[EB/OL].http://www.paper.edu.cn,2014.
[14]祁晓玲,赵霞霞,靳伍银.基于机器视觉的轴类零件几何尺寸测量[J].组合机床与自动化加工技术,2013(1):65-67.