Research On Visual Measurement System Of Specific Size Of Plate Like Parts Based On DXF File

Plate like parts are common parts in mechanical structure,which are widely used in automobile,ship,aerospace and other fields.With the rapid development of manufacturing industry,the processing technology of plate like parts is becoming more and more perfect,and the accuracy of various mechanical processing equipment is also increasing.However,after each process is completed,the traditional manual detection is still used,and the detection efficiency is low,It costs a lot of manpower and financial resources,and most of the traditional measurement methods are contact measurement,which is easy to scratch the surface.In view of the above problems,this paper adopts the method of visual measurement,and proposes a method based on the entity data extracted from the DXF file of the part to guide the matching positioning and measurement of the size to be detected in the image collected after each process,The visual measurement data is compared with the entity data extracted from DXF file to judge whether the process is qualified or not.This paper takes a certain type of plate parts as the research object.Firstly,it studies the data structure and entity data acquisition method in DXF file.The graphics file established by DXF format can be written into standard ascii code.At the same time,the elements contained in DXF graphics file can be extracted for interactive use in other graphics interactive software of computer.DXF file has the advantages of generality,flexibility and flexibility The advantages of good readability and high storage accuracy provide a strong support for the implementation of the method;The second step is to build the measurement system,including the selection of hardware facilities and the design of software system;The third step is to process the collected image,which is mainly the extraction of image edge and the fitting of geometric elements.Canny operator is used to extract the image edge,and the least square method is used to fit the geometric elements.Then the matching location based on DXF file is carried out.The matching location based on DXF file is based on the edge gradient direction matching algorithm,Supported by the DXF graphics file and the data contained in it,it is equivalent to a part design drawing of a given machine vision measurement system,which contains the dimensions of the geometric elements to be measured.The edge of the part image obtained by the vision measurement system is matched and aligned with the fitted geometric elements after fitting the line segment,circle and arc in the extracted image edge,Automatically identify the parts to be measured,and finally measure the specific size of the part image.The experimental results show that the relative error of the measurement system for specific geometric elements is less than 4%,which meets the needs of measurement.