A Positioning Method For V-cut Machine Based On Machine Vision

In this thesis,the study is based on a company's production of CNC V-Cut machine. The platform of V-Cut machine has only one degree of freedom and the PCB to be cut moves along with the load platform in a direction with a linear reciprocating motion. Before cutting the PCB, the distance between the positioning holes of the PCB and its testing line is manually measured as the correction value of the CNC system of V-Cut machine, and input this value into the system to control program of the V-Cut machine through the computer interactive interface. In this way, making the system origin and mechanical origin of the CNC V-Cut machine coincidence to achieve the purpose of positioning.Therefore,the positioning of the original CNC V-Cut machine method is mainly measured by the workers who operating the machine. Obviously, because of the manual measurement introduces a large error, V-Cut machine is difficult to achieve the ultimate positioning accuracy requirements, and reduce the factory production efficiency.Aiming at the working principle of the CNC V-Cut machine and the shortcomings of the original positioning method, this thesis designs a machine vision positioning system to replace the original manual positioning operation and proposed two sets of measurement program. It includes the hardware system and the software system. The hardware system consists of camera, light source, electric moving table, grating scale and load platform. The software system includes image acquisition, image processing, camera calibration and grating reading. In order to ensure the accuracy of high measurement and short measurement distance, the system is set to collect the image at two position.In the first program the distance between the two position is measured by the electromagnet, and the measured distance is calculated indirectly by the data from the electromagnet and the image processing.The second program is through the image mosaic technique to the collection of two PCB images tiled into a mosaic image and calculate the distance directly.The thesis mainly includes the following content:1. Aiming at the positioning principle and positioning accuracy of CNC V-cutter,a machine vision positioning system is designed and its hardware system and software system are designed in detail.2.The camera must be calibrated first, depending on the need for visual positioningand the purpose is to eliminate image distortion to correct the image. Based on the camera model, the principle, the process and the calibration result of the camera calibration are described in detail.And then through the the image mosaictechnique based onbinocular calibration to the beginning and end of the PCB image tiled into a mosaic image. Finally,the results of camera calibration are verified by measuring the standard gauge block.3.In this thesis, some of the image processing algorithms used to extract the PCB positioning marks are analyzed in detail and the algorithms are implemented by the program in order to measure the PCB positioning marks after the camera calibration.Finally,the positioning marks are measured in the corrected PCB image.4.The preparation of human-computer interaction interface.