High-precision Surface Construction And Isosurface Generation Based On Laser Scanning

Industrial production becomes more and more automatic and intelligent.The traditional method of polishing propeller shaft manually,due to its low efficiency and high cost,becomes incompatible with modern shipbuilding industry,and a new automatic method is urgently needed to meet the demand for high efficiency in propeller shaft assembly.Using laser radar technology is a new method to improve efficiency in propeller shaft assembly.A robot equipped with a laser scanner scans the aseembly surface of the propeller shaft.Based on the theredimensional reconstruction of the assembly surface,we generates a high-precision surface to guide the grinding of the assembly surface and this work improve the assembly efficiency greatly.Based on the three-dimensional reconstruction technology by laser,this paper designs a robot-based laser's moving scanning system and real-time monitoring and data processing system based on freedom surfaces.The main work of this paper is as follows:(1)The paper designs and imprements a robot-based moving scanning laser system.According to the analysis of project requirements the paper selects a robot,a laser scanner and other equipment and a laser scanning system based on robots is set up by these equipment.The acquisition and synchronization of laser data and attitude data are studied and implemented.(2)Three-dimensional reconstruction and preprocessing of point cloud are realized.The theory of point cloud generation and related algorithm of point cloud preprocessing are studied.Based on the features of the assembly surface,the algorithm of point cloud filtering and point cloud reduction is verified and implemented,and several filtering algorithms are compared.A real-time monitoring and data processing system is designed to achieve real-time communication and monitoring with the robot.Based on this system,some algorithm,such as point cloud generation,preprocessing,surface construction,and isosurface generation,are realized.(3)Research and realization of bicubic NURBS surface generation.The paper study the generation theory of NURBS curves and NURBS surface,and extend from cubic NURBS curve theory to bicubic NURBS surface.This paper collects actual surface data to calculate the node vector,the control vertex and weight factor of surface.Finally,the bicubic NURBS surface is constructed.Based on the study,this paper studys the surface splicing.The experiment is designed to verify the accuracy of the NURBS surface from two perspectives to meet the project requirements.(4)Realization the construction of the isosurface based on NURBS surface.According to the requirements of the project,the principle of isosurface generation is analyzed and the fitting datum surface based on the discrete points is studied.And then the paper calculates the actual grinding distance of each point based on the datum plane,and uses the discrete points to construct the interpolation grid based on NURBS surface.The grinding distance isosurface is constructed.Finally,the paper design experiments verify the feasibility and accuracy of the isosurface on NURBS surface.