复杂曲面激光测量与重构相关技术研究

【作者】 李春玲；

【导师】 路长厚；

【作者基本信息】 山东大学 ， 机械电子工程， 2005， 硕士

【摘要】 产品数字开发技术是现代产品开发技术中的核心技术之一。逆向工程是实现产品数字开发的重要方法,成为当今研究的一个热点方向。它被广泛用于翻制模具、复制零件、快速原型制造等方面。 论文总结了现阶段国内外逆向工程的研究和应用成果,对点云获取的不同方法进行分析和比较;论述了利用激光扫描仪LSH-800进行曲面测量的原理、方法和关键问题;对复杂曲面进行了激光扫描测量。 论文详细研究了点云数据的处理问题,针对实物样件进行数字化时,不能在同一坐标系下将产品的几何数据一次测出的问题,即点云数据的坐标定位问题,采用基本像素进行定位的方法,将多次扫描得到的点云资料整合在同一坐标系下,解决了点数据输入软件时点坐标不统一的现象。用这种方法进行定位可以得到很高的整合精度。 采用角度判别法,对点云数据中的误差点进行删除,并利用surfacer软件的强大功能,对点云数据的精简、点云数据的特征识别、数据分割等关键问题进行了分析研究,为后续曲面重构的准确性奠定了基础。 对逆向工程中曲面重构的基本理论进行了探索;研究了如何应用计算机辅助设计技术,进行三维曲面的拟合、延伸、剪切、求交等混和运算问题,探索出复杂自由曲面重构的方法和规律;研究了进行逆向工程项目时,在点云数据的精度和客户要求已知的情况下,曲面构建过程中,对曲线和曲面的拟合误差的分配方法。 由于构建倒角曲面时,在三个倒角的交界处经常会出现三边所形成的破洞,虽然Surfacer提供了直接构建三边曲面的功能,但由软件直接创建的三边曲面补片容易出现尖点,而且和周围的曲面缝补起来后形状不易调整。针对此问题,本文提出了在Surfacer环境中用“辅助法”构建三边曲面补片的新方法,该方法有效弥补了Surfacer的不足,具有很好的使用价值。 最后作者运用Surfacer软件对螺旋锥齿轮模型的构建进行了研究,并进行了螺旋锥齿轮的三维CAD造型。利用该模型能够方便进行运动仿真分析,齿轮修形和更多还原

【Abstract】 Digital development is one of the key technology for product development nowadays. Reverse Engineering is an important method to carry out product digital development. It is widely used in reproducing module and replicating accessory and rapid prototype manufacturing and etc.Researching and application achievement about reverse engineering in country and abroad are summarized, and several approaches to obtain point clouds are analyzed and compared. The principle and the method, as well as the key problem in surface measurement using Laser Scan Machine LSH-800 are discussed in detail.Author researches the management problem of point clouds in detail. In reverse engineering, When we measure an existing object, sometimes we cann’ t measure the whole object in one coordinate system, so we must measure the object by several times. Then the point clouds should be settled in the same coordinate system, namely coordinate orientation matter. In the paper, author puts forward primitive element method which can make point clouds in different coordinate system in the same coordinate system. If we use this method on the point clouds, its presicion will be very high.In this paper, author uses angle distinguish method deleting error points. Also the sampling and the feature extraction and segmentation of point clouds are analyzed and reaseached to make surface reconstruction more exactly.In this paper, the essential theory of reverse engineering and surface reconstruction are researched and explored. Further more, author researched how to deal with 3D surface with CAD technology and summarized rule and method. Also, author put forward an error distribute method during surface reconstruction when we carried out a reverse engineering project.When we construct a fillet surface, a three-triangle hole willoccur. Although we use Surfacer can deal with the three-triangle hole directly, a tine point will occur in the three-triangle patch which is obtained by Surfacer directly, moreover it cann’ t patch with neighbour surface successfully. Aimed at this question, author put forward a method called assistant method to construct three-triangle patch. This method compensate the shortcoming of Surfacer, so it has good application value.In the last part of this paper, author researched the construct process of spiral bevel gear in reverse engineering Surfacer environment. Using this CAD model , we are able to carry out movement simulation analysis, we are able to modify tooth pattern, to optimize the design of the gear, and to provide basic gear data to CNC and die cutting.If the theory and application of Reverse Engineering in the industry design fields are researched in detail, the level of industry design would be improved, the cost of the product design would be reduced, the period of the development would be shorten, the competition of the product in international market would be improved. The study of this paper enriched the theory and method in the sculpt and design of industrial product, and would promote the application and popularization of reverse engineering in industry design field.更多还原