Research On 3D Measurement For Inner-Contour Of The Thickened End Of Drill Pipe Based On Computer Vision

Drill pipes are important instruments in exploiting petroleum. The geometric parameters and quality of drill pipes need to be measured accurately and controlled strictly during production. So, Measurement for inner-contour of pipe figure components is a subject which has significant practical value and academic research significance. The specialty of drill pipe, e.g., closed, unseen, and narrow spaces, leads to many difficulties during parameter measurement and inner-surface inspection. Therefore, how to measuring the parameters and learning the inner-wall of drill pipe rapidly and efficiently is always a big problem.The new non-contact measurement method needs to be proposed for the inner-contour of drill pipe. At the same time, how to evaluate the quality according to the captured data is a problem waitted for solving. After reading many references and completing many preresearch works, the new visual method based on automatic gain ringy discrete structured laser was proposed, which can be used to capture the cloud data of inner-contour. The new structured laser was composed of multimode optical fiber component and laser device component whose sigle intensity could be controlled independently. The new method employed the high-resolution industry CCD to capture the inner-contour’s cloud data. On the base of captured cloud data, the inner-contour parameters can be calculated.After reading many references, we classified and analyzed all the measurement methods metioned in these references, and pointed out the advantages and disadvantages of different method. A new ringy structured laser was designed in the dissertation. On the basis of the new ringy structured laser, an experiment system was constructured and calibrated for verifying the validity and practicality of the new methods. For improving the precision of the measurement system, some work was done for correction the distortion of non-linear component (large-angle lens).The fast algorithms for capturing the inner-contour cloud data and extracting inner-contour feature parameters were proposed in this dissertation. The new algorithm was composed of several steps, which were generatrix resample, generatrix filter, falling method division, subsection linear fitting and inner-contour feature parameters extracting. In the experiment, the new methods obtained well performace on anti-disturbance ability and stability, and got enough measurement precision.The software if coded in visual basic 6.0 integrated environment. The functions include measuring modes controlling, image capturing, image processing, data processing and data saving. Besides, it provides a convenient interface for operators.