Object Surface Defect Detection Method And Experimental Research Based On Line Structured Laser

In today's world,the development of science and technology is increasingly rapid,people have higher and higher requirements for the quality of industrial products.As a result,a variety of detection technologies have emerged,and object defect detection is one of the important applications.In recent years,line structured laser technology was popularized in defect detection,which belonged to the field of three-dimensional vision measurement.It takes advantage of contactless measurement to eliminate electromagnetic interference by means of electrical measurement.At the same time,it has a great advantage in detection efficiency,suitable for real-time measurement sceneses.Based on the measurement principle of the laser triangulation method,this paper took advantage of the laser projection device,the image acquisition device,and the displacement transmission device to build the object defect detection system with the line structured laser,which can scan the surface of the object,and determine the system parameters through the calibration processes,obtain two-dimensional data through the image processing algorithm,and calculate three-dimensional coordinates using the matrix transformation to extract the depth informations of the object,and then complete the detection of surface defects.The paper explored the following in depth:First,the operating principle of the laser triangulation method was briefly introduced,and the two types of projection methods were compared and analyzed.According to the theoretical results and the actual requirements,the detection scheme was determined.Second,the theoretical model of the system was establishing,based on the model,a line structured laser detection system was designed and built,and the workflow was briefly described.Third,various parameters of the system were calibrated using checkerboard and sawtooth targets respectively.According to the principle of cross ratio projection invariance,the comprehensive calibration method based on two-dimensional planar target was proposed.Fourth,the light intensity distribution of the laser streak images were studied,preprocessing the images,and several common streak centerline extraction methods were described,in order to elicit a new method of extracting centerline by the gray center of gravity method in the direction of the cross section of the laser streak,besides comparing and analyzing the advantages of this method.Fifth,scatter dataes were obtained by matrix operation,and the corresponding relationship between depth and gray was established,so the dimensionality reduction conversion from a three-dimensional points cloud to a gray image was realized.The surface morphological change of the object was reflected according to the situation of the gray distribution,so that achieving the purpose of defect detection.According to the experimental results,it was found that the system had good measurement accuracy and also had certain advantages in working efficiency,which was able to meet the requirements of most application situations.