Research On 3D Measurement And Reconstruction For Inner-Contour Of Pipe Figure Components

Pipe figure components can be found everywhere in our lives: municipal sewage pipes and fresh-water pipes, petroleum pipes, fibers or cable pipes imbedded underground or at the bottom of the sea, gun barrels and cannon barrels, deep holes in workpieces, etc. All of these pipe figure components with rough inner-surface are made from different materials and have different shapes and sizes, whose geometric parameters and quality need to be measured accurately and controlled strictly during production. So, Measurement and reconstruction for inner-contour of pipe figure components is a subject which has significant practical value and academic research significance. The specialty of pipe figure components, 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 pipe figure components rapidly and efficiently is always a big problem.The new non-contact measurement method needs to be proposed for different pipe figure components with different materials and sizes. At the same time, how to evaluate and reconstruct the inner-contour of pipe figure components 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 and the inner-contour can be reconstructed. Before research proposalling, a novelty retrieval work was done for the measurement methods and the data processing methods proposed in this paper. The novelty report showed that these new methods have certain innovation.The subject mainly includes two aspects, which were the research on the measurement and reconstruction method for inner-contour of pipe figure components. The two relative independent aspects have a close relationship. The first aspect mainly complete the cloude data capturing and characteristic parameters calculated, and the second aspect mainly reproduction the inner-contour of pipe figure components.According to the two main research aspects, this dissertation compeleted many works summarized as follows:1. 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. At the same time, we summarized the difficults and defects of available surface reconstruction methods.2. Combining the existed visual measurement methods, four new methods were proposed in this dissertation, which were Symmetrical Distributed Structure method, Vertical distributed structure method, External-reflection Integrated Structure method and Internal-reflection integrated structure method. According to the structure of the four methods, the mathematical model was built correspondingly.3. 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).4. 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 difference, 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.5. Lastly, reference to the reconstruction processing of free closed surface, a new reconstruction method for inner-contour of pipe figure components was proposed, which named as active subdivision 3D reconstruction method based on generatrix characters. The new method was compoed of three steps, which were closed surface subdivision, single surface reconstruction and surface blending & suture. Firstly, the closed surface subdivision employed active subdivision method based on generatrix characters. Secondly, the single surface was reconstructured by NURBS surface. Thirdly, all these surface patchs were blent and sutured by the cubic spline or the bicubic curved surface of coons. In the experiment, the new method could compeleted the inner-contour reconstruction of pipe figure components fastly, and obtained higher reconstruction precision.In conclusion, all the research works in this dissertation can give a guide to develop the similar measurement apparatus, at the same time, in practice, which can improve measurement efficiency, reduce labor intensity, and bring significant economic benefits.