Research On Inspection Method Method Of Pipeline Inner Surface Defects Based On Machine Vision

Pipeline transportation,as an efficient and economical mode of transportation,plays an important role in the national economy.With the extension of service time of pipeline,due to the aging of pipeline material,corrosion and erosion of conveying media,pipeline leakage accidents occur from time to time,which will not only cause waste of raw materials and products,but also cause serious casualties and serious environmental pollution.Therefore,pipeline defects,especially internal surface defects,are accurately detected.It is of great significance to grasp the defect status and development law in time for ensuring the normal operation of pipelines and reducing losses.Based on the theory of computer vision inspection and the method of combining theory with experiment,the method of pipe inner surface defect detection based on machine vision is studied in this paper.In this paper,aiming at the industrial pipeline system with a diameter of 80-200 mm,a three-dimensional visualization inspection system of pipeline inner surface defects based on circular structured light is designed,which combines the related characteristics of pipeline inner surface environment,monocular vision and circular structured light.Considering the narrow space of the inner surface of the pipeline,the circular structured light laser and the camera are arranged longitudinally to collect the image of the inner surface of the pipeline.The image processing algorithm of circular structured light strip is studied,including image preprocessing,image binarization,strip center extraction,sub-pixel position acquisition and strip center fitting,etc.An improved strip center extraction algorithm for circular structured light strip is emphatically studied,which can extract strip center accurately and quickly.According to the working principle of circular structured light and the characteristics of monocular camera,two calibration methods are compared experimentally to find a suitable calibration experimental method,so as to better detect the size of defects on the inner surface of pipeline.The improved strip center extraction algorithm is used to obtain the strip center point of circular structured light.Combined with the calibration method,the three-dimensional point cloud data on the inner surface of the pipeline are obtained.Then the three-dimensional morphology visualization of the inner surface defects of the pipeline is realized by MATLAB programming and the size of the defects is obtained.The experimental results show that the system uses the improved algorithm to extract the center of the circular structured light strip with higher accuracy.It can extract the center of the circular structured light strip accurately and efficiently,reduce the defect detection error,make the relative error of defect measurement less than 1%,and realize the visualization of the three-dimensional shape of the inner surface defect of the pipeline,and achieve the expected goal.The research work has certain theoretical significance and engineering application value.