Research On The Machine Vision Measuring System Of Circumferential Hole Position Distribution

Circular hole is the basic structure of many parts,its manufacturing quality is directly related to the performance of parts.It's the key factor affecting product assembly quality,and the combination of holes in the circle is difficult to detect.So the development of circumferential hole location distribution Machine vision inspection system is necessary.The thesis analyzes the composition of the system,proposes an image sharpness evaluation function combining the SMD function and the energy gradient function,and realizes the accurate measurement of the position of the circumferential hole.The main error of the detection system is analyzed,the corresponding error compensation scheme is given,and the feasibility of the compensation scheme is verified experimentally.The main contents of the full text are as follows:Chapter 1:The paper introduces the background and significance of the research,summarizes the research status of the machine vision system,and introduces its key technologies such as auto-focusing algorithm,camera calibration technology and the method of hole location detection.Finally,the main contents of the full text research and the framework of the thesis are given.Chapter 2:The overall scheme of the visual measuring system for circumferential holes is given.The four-axis motion platform is designed and the hardware selection of measuring systems such as camera,lens,light source,grating ruler and motion control card is completed.The related functions of circumferential hole visual measuring system are analyzed.Software modules such as initialization,motion control,image acquisition,image processing,result output and auxiliary functions are introduced.The calibration of the vision system camera is discussed.Chapter 3:By contrasting the three kinds of image sharpness evaluation functions,such as time domain method,frequency domain method and statistical method,an image sharpness evaluation function combined with SMD function and energy gradient function is proposed.Through the processing of the collected 30 images with different degrees of focus,the advantages and disadvantages of the proposed evaluation function and other evaluation functions are analyzed and compared in terms of focusing accuracy,sensitivity and computational efficiency.Chapter 4:The calculation model of circumferential hole location is given.Comparing six kinds of classical edge extraction operators,it is concluded that the Roberts operator has the best effect on the edge extraction of cabin socket holes.By improving the least squares method,a circular algorithm based on iterative least square method is proposed,which can reduce the measurement error caused by edge contour defects.Chapter 5:The error source of the circumferential hole visual measuring system was analyzed.Established a mathematical model for the major error sources and presented a compensation scheme.The compensation scheme was given and its feasibility was verified.Finally,the final experimental results of the visual measurement of the distribution of circumferential holes are given.Chapter 6:Summarize the main research results of the full text and prospect the further research.