| Pipeline is increasingly becoming the primary means of transporting oiland gas because of its characteristics such as security, economic and efficient,and it is also broadly used in the chemical industry. But the objects thatpipeline transports have the characteristics such as flammable, explosive,highly corrosive, etc., so regular inspection and maintenance for pipeline is ofgreat significance to the safety of production.This thesis centers around the National Natural Science Foundationproject-Pipeline internal surface3D shape visual inspection theory andtechnology studies,takes the industrial pipe which inner diameter between70mm-200mm as the object, aims at the design, calibration and the issuesinvolved for realization of in-pipe surface vision inspection system，morein-depth research are conducted from theories, methods and experiments.According to the characteristics and requirements of the inspection system,this paper chooses the vertical arrangement of the camera and laser, which caneffectively reduce the lateral dimensions of the laser and vision sensor, and thesmall structural model of the structured light vision inspection system isguaranteed. Then the planar target fitting system characteristics is designed touse Zhang’s camera calibration method，and a method that based on the homography and the planar target to construct space circle structured lightcalibration points is proposed. This method allows the camera calibrationsimultaneously with the circle structure light calibration, and the entirecalibration process is carried out on the spot so that the errors caused by thesystem structural differences can be significantly reduced. In addition, thispaper focuses on the in-pipe surface image feature information extractionalgorithm, through the threshold contrast as well as the neighborhooddetection to filter out the noise, and get the accurate extraction results of thecircle structured light center.In this paper, the actual industrial pipe is measured using the proposedexperiments which comes from the measurement of using the proposedin-pipe surface inspection system, and the results are calculated by VC++6.0and MATLAB programming. The experiments show that the system has theadvantages of good visualization and it can achieve high accuracy of in-pipesurface inspection. |
PDF Full Text Request