基于机器视觉的螺纹参数检测及评定系统设计

发布时间：2018-03-25 19:03

本文选题：机器视觉　切入点：LabVIEW　出处：《南昌航空大学》2017年硕士论文

【摘要】：螺纹连接是工业生产领域常见的机械连接方式,其几何参数对于一些紧密器械的性能有重大的影响。随着机械行业的迅猛发展,工业领域对于螺纹的检测技术日益提升。传统的螺纹检测技术在检测精度、检测效率方面越来越难达到工业领域的要求,因此提出了将机器视觉技术应用到螺纹参数检测中去。作为一门新兴科学,其中心思想在于通过计算机将获得的图像进行分析、计算并得到螺纹的各项参数,相对于传统的检测手段来说,将机器视觉技术应用到螺纹的参数检测中具有检测效率高、自动化程度高等优点,能够实现螺纹的非接触测量。本课题以设计高效的普通外螺纹参数测量系统为研究方向,提出了一种基于机器视觉的外螺纹参数测量及合格性评定系统。主要包括以下几个方面:(1)搭建了螺纹参数测量的硬件平台,主要构成包括光源、CCD摄像机、镜头、图像采集卡、计算机,其性能要求满足纹参数检测系统的测量任务和系统要求。(2)以LabVIEW虚拟仪器作为螺纹参数检测的软件平台,深入研究LabVIEW虚拟仪器的内置视觉模块的功能及作用,设计了图像采集模块、图像处理模块、螺纹边缘检测模块、特征值提取模块、螺纹参数计算模块和合格性评判模块。(3)研究了螺纹图像处理及螺纹参数计算的相关算法,通过图像预处理的方法,从螺纹原始图像中得到了螺纹图像轮廓的的相关信息。同时进一步设计了螺纹各项参数的计算方法,包括大径、中径、小径、牙型半角、牙高、螺距,并根据和光学显微镜的测量数值进行对比验证系统的有效性。(4)根据视觉系统的标定原理对检测到的参数像素值进行了实际物理量的变换,同时分析了系统误差并提出了改进误差的方案。(5)在LabVIEW虚拟仪器平台的基础上设计了螺纹合格性评判系统,对检测后的螺纹的合格性进行了判断。
[Abstract]:Thread connection is a common mechanical connection in the field of industrial production. Its geometric parameters have a significant impact on the performance of some compact instruments. The traditional thread detection technology is becoming more and more difficult to meet the requirements of the industrial field in terms of accuracy and efficiency. Therefore, the application of machine vision technology to thread parameter detection is proposed. As a new science, the central idea of machine vision is to analyze the images obtained by computer and to calculate and obtain the parameters of thread. Compared with the traditional testing methods, the application of machine vision technology to the parameter detection of thread has the advantages of high detection efficiency, high degree of automation and so on. The purpose of this paper is to design an efficient measuring system for the parameters of external thread. In this paper, a machine vision based external thread parameter measurement and qualification evaluation system is proposed. The hardware platform for thread parameter measurement is built including the following several aspects: 1) the hardware platform of thread parameter measurement is built, which consists of light source CCD camera, lens, image acquisition card, etc. The computer, whose performance requirements meet the measuring tasks and system requirements of the grain parameter detection system, takes the LabVIEW virtual instrument as the software platform for thread parameter detection, and deeply studies the functions and functions of the built-in visual module of the LabVIEW virtual instrument. Image acquisition module, image processing module, thread edge detection module, eigenvalue extraction module, thread parameter calculation module and eligibility evaluation module. Through the method of image preprocessing, the relevant information of thread image contour is obtained from the original image of thread. At the same time, the calculation method of various parameters of thread is designed, including large diameter, middle diameter, small diameter, tooth shape half angle, tooth height, pitch, etc. The validity of the system is verified by comparing it with the measurement value of optical microscope. (4) according to the calibration principle of the vision system, the actual physical quantities of the detected parameter pixel values are transformed. At the same time, the system error is analyzed and the scheme of improving error is put forward. Based on the LabVIEW virtual instrument platform, the thread eligibility evaluation system is designed, and the thread eligibility after testing is judged.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG85;TP391.41

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