Research On Positioning Module Of Stone Unloading Device Based On Machine Vision

Because of its stable physical and chemical properties,natural stone is widely used in construction and decoration fields.Stone unloading operation is an essential link in the production of granite SLATE.In China,stone unloading operation is completed manually,which has low production efficiency and high work intensity.In this paper,to solve the above problems,the design of stone plate unloading device,the use of machine vision technology to obtain the location information of each slab,the use of location information guide stone plate unloading device to complete the stone plate unloading operation.The main research contents of this paper are as follows:(1)Through the analysis of the positioning module of the stone plate unloading device,the overall scheme of the positioning module of the stone plate unloading device is determined,including the hardware selection of the image acquisition and positioning module,and the lifting rotary table used for adjusting the stone square material and the stone plate unloading device used for the operation of the stone plate unloading.(2)Build the experimental platform and calibrate the camera.An experimental platform for image acquisition on the top of the slab was constructed,and the imaging model and lens distortion of the camera were analyzed.The image of the checkerboard calibration plate was collected by the experimental platform,and the internal and external parameters of the camera were obtained by using Zhang’s calibration method.The calibration experiment results were analyzed by using the reprojection error.(3)Image preprocessing of the slab top.The experimental results of different image filtering denoising,binarization and morphological processing methods were analyzed,and the image pretreatment of the top of the SLATE was carried out to eliminate the noise,holes and other interference information in the collected images,so as to reduce the influence on the subsequent experiments.(4)Edge detection and visual positioning of the top image of the SLATE.Several common edge detection operators are analyzed,and Canny edge detection operator is selected to extract the contour of the top image of the SLATE.The area of the extracted contour was calculated,and the top contour of the SLATE was screened out.The minimum external rectangle method was used to achieve the fitting of the top edge of the SLATE,and the corner information of the top edge of the SLATE was obtained.The center of mass of the top of the SLATE was obtained by the gray centroid method.Establish the coordinate system between the machine vision module and the target workpiece,solve the three-dimensional coordinates of the top of the SLATE,realize the positioning of the target SLATE,using the three-dimensional coordinates,drive the motor to drive the stone plate unloading device to unload the SLATE from the SLATE base.