Design Of NC Machining Self-correcting System Based On Machine Vision

With the development of miniaturization of electronic products,micro-circuits have put forward higher requirements for the processing accuracy of PCB boards.Installation error is one of the main factors affecting PCB processing accuracy.For example,when PCB board is installed on the engraving machine,because of the flatness and deflection angle of the fixture,there are positioning errors in the installation link,which directly affects the positioning accuracy of the circuit diagram on the PCB board.In this paper,based on the principle of'visual positioning,a self-correcting algorithm is proposed.Combining with the processing conditions,the installation error is eliminated.By comparing the processing accuracy through experiments,it is concluded that the self-correcting algorithm can effectively improve the processing accuracy.The right-angle vertex of PCB is used as MARX point,and the Hough intersection method is used to precisely locate the coordinates of MARK point.Hough line has the characteristics of strong anti-light instability and insensitivity to local deletion.Its principle is to transform image space into parameter space.Using this method,right-angled image is processed,and then accurate linear equation is obtained.Then,MARK point coordinates can be obtained by solving two right-angled side equations together.This method can also reduce the image positioning error caused by PCB plate deformation caused by clamping fixture.By analyzing PCB board coordinate system,image coordinate system,mechanical coordinate system and their corresponding relations,the self-correction algorithm is established.From the mapping relationship between image coordinate system and mechanical coordinate system,the corresponding relationship between actual object size and pixels is obtained;from the mapping relationship between PCB coordinate system and mechanical coordinate system,the processing G code is obtained;through calculating the position relationship between non-standard and standard PCB installation,the self-correction algorithm is used to correct the G code,so as to obtain more accurate processing G code.The hardware platform of PCB engraving machine is constructed.The relationship between non-standard and standard PCB board is compared.The precision analysis model and calculation process are given.The feasibility of the self-tuning system is analyzed based on the experimental process.