视觉坐标测量系统的自动对焦策略研究  

Study on Automatic Focusing Strategy of Vision Coordinate Measuring System

作　　者：毕超 张洋 张超 周鹏 Bi Chao;Zhang Yang;Zhang Chao;Zhou Peng(Beijing Precision Engineering Institute for Aircraft Industry,Beijing 100076,China)

机构地区：[1]北京航空精密机械研究所精密制造技术航空科技重点实验室 [2]北京遥感设备研究所

出　　处：《工具技术》2022年第8期136-141,共6页Tool Engineering

基　　金：国防基础科研计划(JCKY2018205B013)。

摘　　要：为了使研制的视觉坐标测量系统自动调整到正焦状态,本文提出了基于改进Prewitt算子与Gaussian函数拟合的自动对焦策略。在自动对焦过程中,控制运动机构使工业相机在对焦区间内以小步长等间距方式采集被测物体的图像序列;通过基于改进Prewitt算子的对焦评价函数计算每幅图像的清晰度,并采用函数逼近法在清晰度峰值点邻近的数据点集上进行对焦位置搜索,应用Gaussian函数对数据点集进行拟合,以获得近似的清晰度曲线;将解析出的峰值点位置作为最佳成像位置,从而实现自动对焦;应用长方体实验件和组合实验件分别进行对焦重复性与对焦精度的验证实验。结果表明,系统的对焦重复性≤0.0030mm,对焦方向上的尺寸测量精度≤±0.0030mm,表明了本文所提出自动对焦策略的可行性和有效性。In order to adjust the vision coordinate measuring system established to the focusing state,the automatic focusing strategy based on improved Prewitt operator and Gaussian function fitting is proposed.In the implementation procedure,the image sequence of the measured target in the focusing range is captured by the industrial camera moving at equal intervals in small steps.The sharpness of every image in the image sequence is calculated by focusing evaluation function based on improved Prewitt operator.To search the focusing position on the point set adjacent to the sharpness peak by the function approximation method,the Gaussian function is utilized to fit the approximate sharpness curve to analyze the peak position,which would be taken as the optimal imaging position.The automatic focusing is realized.The focusing repeatability and accuracy are verified by a cuboid test piece and combined test piece respectively.The results show that the repeatability is smaller than 0.0030 mm and the measuring accuracy on the focusing direction is smaller than±0.0030 mm.Therefore,the experimental results manifeste the feasibility and effective of the automatic focusing strategy proposed in the paper.

关 键 词：清晰度 自动对焦 视觉测量 PREWITT算子 

分 类 号：TG806[金属学及工艺—公差测量技术] TP273.5[自动化与计算机技术—检测技术与自动化装置]