基于SVM和形状特征的电极三维模型分类检索的研究-材料加工工程专业论文.docxVIP

摘 要 计算机硬件、三维模型建模软件及互联网技术的飞速发展，以及三维模型以自 然、直观的方式描述现实世界物体的优越性，极大地促进了三维模型在工业设计、 电子游戏、虚拟现实等领域的广泛应用与普及。 在机械工业领域，传统的二维 CAD 设计已被三维模型建模技术取代，企业数据 库中的三维模型及其加工工艺知识已非常庞大，利用数据库中的相似三维模型及其 数控加工工艺知识，将能快速地完成现有零件的加工方案设计和创新，减少错误的 发生。如何从数据库中快速准确地获取相似三维模型及工艺信息，便成为解决问题 的关键。本文的主要内容就是对三维模型检索和 SVM 分类技术进行实现展开的。 本文通过基于不变矩的两种形状特征提取技术，将三维模型的形状特征描述成 基于 SVM 的特征向量；从形状和数控工艺上分析了电极三维模型的分类指标；提 出了一种以面单元做功方式来数值化描述三维模型形状特征的提取方法，并从理论 和实验上对它进行了旋转、平移和缩放不变性证明；对三种特征提取方法进行了相 似性度量实验和电极三维模型检索实验，结果表明三种方法都达到了较好的检索效 果，且改进算法具有更好的泛化性能；实验分析了四种核函数的性能，确定了最适 合本文的 SVM 分类器和核函数类型，通过 k 折交叉验证法和“晶格”有哪些信誉好的足球投注网站，找到 了 SVM 分类器的最优参数组合，并对六类电极进行分类实验，结果表明准确度达 到 88.6148%，同时还从对其中的两类样本进行分类实验，准确度达到 95.1531%； 提出了三维模型特征向量的数控工艺特征化方法。基于以上理论研究开发了具有使 用性的电极 3D 模型分类检索系统，实现了基于 SVM 和形状特征的分类检索算法， 并已取得较好的分类准确度与检索效果。 关键词：三维模型检索；SVM；分类；特征提取；三维模型 Abstract The rapid development of computer hardware, 3D modeling software and internet technology，as well as the advantages of describing objects in real world by 3D model in natural and visual away, have greatly promoted the widely use and popularization of 3D model in many fields, such as mechanical manufacture, video games and virtual reality. In the field of mechanical industry, the traditional 2D CAD has been replaced by 3D model technology. Huge amounts of 3D models and processing technic have being created and saved in the data base. Using the exiting similar 3D model and its relative knowledge to design a new part and its process plan will increase the design efficiency and reduce mistakes. So how to classify the created model, and find out similar 3D model and processing technic quickly and correctly from a 3D model library has become a issue of design. The main content of this thesis is to realize the 3D model retrieval and SVM based classification. In this thesis, two methods of shape feature extraction both based on invariable moment were applied to construct the SVM vector which describes the 3D model shape feature. Classification criterions of electrode 3D model were put forward from shape and NC machining