| Pipeline transportation is increasingly becoming the primary means of transporting energy such as oil and gas for it's characteristics such as security, economic and efficient. Because the objects that pipelines transport have the characteristics such as flammable, explosive, corrosive, etc., the regular inspection and maintenance for pipelines have great significance to ensureing safety in production.Structured light vision inspection technology based on optical triangulation is widely used in 3D shape measurement for it's features such as non-contact, high precision, fast, highly automated and robust. Let the probe of circle structured light vision inspection system deep into the pipe, accurate 3D measurement of pipe internal surface can achieve. The precise calibration of circle structured light vision inspection system has important significance to improving measurement accuracy of circle structured light vision inspection system, therefore the calibration method of circle structured light vision inspection system has become the research priority of structured light vision inspection technology.This thesis centers around the National Natural Science Foundation project-Pipeline internal surface 3D shape visual inspection theory and technology studies, to the structured light calibration technology and existed problem involved in pipeline internal surface visual inspection system based on circle structured light, conducts some in-depth studies on theory, methods and experiments, and does experimental verification.Based on the study of circle structured light visual inspection principle and the camera and circle structured light mathematical model, this thesis designed calibration method for circle structured light visual inspection system, researched the sub-pixel feature extraction method for circle structured light stripe center and the target corner. Based on the study of structured light calibration method, designed flat target suits circle structured light calibration, raised a method that based on the cross-ratio invariance principle and flat target, let the camera coordinate system as a benchmark, based on coordinate transformation between different planes, construct space circle structured light calibration points. Finally built the circle structured light calibration system, based on VC++ 6.0 and Matlab, achieved the calibration of circle structured light vision inspection system, and conducted error analysis.Experimental results show that the circle structured light calibration method this thesis raised can complete the calibration quickly and efficiently, the calibration precision is high, and the expected goal has achieved. |
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