共查询到19条相似文献,搜索用时 62 毫秒
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基于实物模型的复杂曲面产品的反求技术 总被引:2,自引:0,他引:2
针对反求工程中复杂曲面CAD建模,综合论述了产品造型过程中所涉及到的相关技术。重点介绍了样件表面数字化技术、曲面重构技术及曲面光顺技术。 相似文献
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主要研究复杂曲面的反求技术 ,提出了一种新的反求方法——映射参数分割法 :它将复杂曲面分为广义平面、广义柱面和广义球面三类 ,根据不同特征选择定义映射引导参数面 ;将曲面的检测点集映射到引导参数面 ,形成映射参数域并确定其取值范围 ,实现参数域、检测点集分块 ;通过最小二乘平面逼近 ,形成整体曲面的插值网格点 ,最终采用标准的 Bezier曲面方法实现复杂曲面反求 相似文献
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基于实物的复杂曲面零件反求工程中未知区域测量数据补充及曲面重构技术 总被引:7,自引:0,他引:7
针对基于实物的复杂零件反求工程中含有部分形状未知区域(如裁减曲面中的被裁减部分、测量盲区等)的复杂曲面反求CAD建模问题,提出了三种测量数据补充方法:①局部区域实物填充法。②补充设计数据补充法。③基于逼近曲面或三角曲面的测量数据自动补充法。研究了基于三角曲面模型初始表达的复杂曲面分区NURBS曲面重构方法。最后,给出了结合上述方法和反求工程软件RE-SOFT所解决的摩托车塑料件反求CAD建模实例。实践表明,综合运用所提出的数据补充和曲面重构方法,能够大大缩短实物样件的反求CAD建模时间,提高复杂曲面产品的设计效率。 相似文献
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提出了基于实体特征的自动建模系统SFRE的方案,该方案对实物原型的点云数据进行分类处理,找出形成最简单体元的数据点集,识别体元类型,在商业化造型软件环境下实现体元造型和拼合,以构造原型的CAD模型。SFRE系统由两部分组成:第1部分为自动建模编程软件,在Windows平台上运行,自动编制实现实体造型的程序,完成数据处理、特征识别和构造特征树工作;第2部分为自动造型接口软件,在商业化CAD造型软件环境下运行,实现自动造型,完成三维重构。可实现对具有多形态、多内腔的复杂原型的自动三维重构,为基于原型的产品创新设计奠定基础。SFRE系统特点是:基于实体特征,特征最简,反求建模和正向造型结合,自动化程度高。其是目前已有三维重构技术的必要补充和发展,将为反求工程和快速成形的应用拓宽范围。 相似文献
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Fan Shuqian Ke Yinglin College of Mechanical Energy Engineering Zhejiang University Hangzhou China 《机械工程学报(英文版)》2005,18(4):482-489
A novel method to extract conic blending feature in reverse engineering is presented. Different from the methods to recover constant and variable radius blends from unorganized points,it contains not only novel segmentation and feature recognition techniques,but also bias corrected technique to capture more reliable distribution of feature parameters along the spine curve.The segmentation depending on point classification separates the points in the conic blend region from the input point cloud.The available feature parameters of the cross-sectional curves are extracted with the processes of slicing point clouds with planes,conic curve fitting,and parameters estimation and compensation.The extracted parameters and its distribution laws are refined according to statistic theory such as regression analysis and hypothesis test.The proposed method can accurately capture the original design intentions and conveniently guide the reverse modeling process.Application examples are presented to verify the high precision and stability of the proposed method. 相似文献
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Lü Zhen 《机械工程学报(英文版)》2003,16(3):248-251,263
A new method of extraction of blend surface feature is presented. It contains two steps: segmentation and recovery of parametric representation of the blend. The segmentation separates the points in the blend region from the rest of the input point cloud with the processes of sampling point data, estimation of local surface curvature properties and comparison of maximum curvature values. The recovery of parametric representation generates a set of profile curves by marching throughout the blend and fitting cylinders. Compared with the existing approaches of blend surface feature extraction, the proposed method reduces the requirement of user interaction and is capable of extracting blend surface with either constant radius or variable radius. Application examples are presented to verify the proposed method. 相似文献
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基于三角Bézier曲面的复杂特征模型重建及特征融合技术研究 总被引:6,自引:2,他引:4
针对复杂过渡特征零件的建模问题,提出了一种新的H角Bezier曲面反求建模方案。应用局部网格点追加和网格拓扑关系调整等技术,较好地解决了三角曲面建模中分块搭接时在特征走向变化区域存在的“X”和“T”形相交特征的融合问题。应用实例表明,基于分块建模、曲面搭接以及特征融合的三角曲面建模方案,可以得到特征表达完备的高质量曲面模型。 相似文献
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Ke YinglinSun QingLu ZhenCollege of Mechanical andEnergy Engineering Zhejiang University Hangzhou China 《机械工程学报(英文版)》2003,16(2):163-166
The main purpose of reverse engineering is to convert discrete data points into piecewise smooth, continuous surface models. Before carrying out model reconstruction it is significant to extract geometric features because the quality of modeling greatly depends on the representation of features. Some fitting techniques of natural quadric surfaces with least-squares method are described. And these techniques can be directly used to extract quadric surfaces features during the process of segmentation for point cloud. 相似文献
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The key issues such as vision sensor, sampling planning are studied for reverse engineering. For the developed sensor, the low sensitivity to the incident angle and the high linearity between the output and the input are carried out. During digitizing, the adaptive sampling planning method based on the curvature of surface and the slope of tangent line of measured point is proposed. After integrating the vision sensor, CNC milling and relevant software, the reverse engineering system based on computer vision is developed. The experiment shows that this system is reliable and efficient. 相似文献
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Tian Xiaodong Zhou Xionghui Ruan XueyuNational Die & Mould CAD Engineering Research Center Shanghai Jiaotong University Shanghai China 《机械工程学报(英文版)》2002,15(3):238-242
Triangulation of scattered points is the first important section during reverse engineering. New concepts of dynamic circle and closed point are put forward based on current basic method. These new concepts can narrow the extent which triangulation process should seek through and optimize the triangles during producing them. Updating the searching edges dynamically controls progress of triangulation. Intersection judgment between new triangle and produced triangles is changed into intersection judgment between new triangle and searching edges. Examples illustrate superiorities of this new algorithm 相似文献