基于拓扑结构分析的实体特征造型理论与方法

Computer aided geometric modeling performs an important role in industry and national defense. Recently, the development of modeling technologies is facing the urgent requirement as well as the bottleneck to apply the flexibility of the free-style modeling mode for entertainment industry to the precise feature-based solid modeling for manufacture industry. For example, the result topology will have a sudden change if the feature parameters are modified to be out of some threshold. This usually leads to an exception of the program or the malfunction of the algorithm. From the aspects of geometry and topology, this project will study the essential difficulties to combine the benefits from the free-style modeling and the feature-based modeling. This project will also try to establish the theory foundation of the coverage of the feature parameter space, as well as the methods of topological analysis for the complex structures in solving the problems of feature-based model construction. The project will base on the study and practice of the applicants’ institute, which has a thirty-year research and development experience of geometric modeling systems with independent intellectual property rights. Starting from the solid extrusion and fillet operations, the project will study the modeling theory and methods based on featuring, topological reconstruction and topological analysis. It will also expand the coverage of the feature parameters, enhance the flexibility of operations, and finally improve the performance and quality of geometric design. The achievement of the project will be applied to the geometric modeling of vehicles and equipment of nuclear reactor in order to serve national economy and defense.

计算机几何造型对工业与国防都具有重要作用。如何将面向娱乐业的自由造型的灵活性融入到面向工业设计的精确实体特征造型当中是当前的迫切需求和发展瓶颈。目前当特征参数变化超过阈值时，结果实体拓扑结构的突变往往会导致造型算法失效或程序异常。本项目拟从几何学与拓扑学的角度分析自由造型操作与特征造型之间难以融合的问题本质，建立特征造型的特征参数空间覆盖域的理论基础，形成适用于特征造型的拓扑结构分析以及在特征造型操作下的复杂拓扑结构变化分析理论与方法。本项目将以依托单位所拥有三十多年的自主知识产权的造型软件系统为基础，将上述理论与方法应用于具体的实体特征造型操作之中，以实体拉伸和过渡操作为切入点，研究基于拓扑结构分析与拓扑重建的实体特征造型操作理论和方法，从根本上拓广特征造型的覆盖域范围，提升操作的自由灵活程度，从而提高设计效率与质量，并用于汽车与核反应堆装备几何建模之中，为国防和国民经济做出贡献。

计算机三维几何造型已成为服务于各行业的支撑性技术，而当前基于特征的实体建模的灵活性和稳定性是制约其发展的瓶颈问题之一。本项通过研究特征参数变化所产生的算法失效和过程异常等问题，提出了在拉伸、过渡等特征建模操作中增加参数自由度的理论方法和解决方案，可提高三维建模操作用户输入容错能力。在研究过程中，研究团队意外探寻到了解决三维设计协同、特征造型和动画驱动的关键性的新方法，并在新方法的实现、验证和示范方面做出了具有创新性和突破性的案例。该方法提出了基于程序式半结构化三维设计理论，通过将三维设计工作抽象为约 50 个控制元语，通过计算机程序编制的方法利用这些元语的串行组合控制空间中的三维图龟，利用三维图龟的扫掠形成三维形体。该方法打破传统特征设计方法，而是利用程序流程控制形体生成，在形体特征生成上拥有传统方法不具备的自由性，同时将成熟于程序设计领域的协同设计等方法融合入三维设计，能够创造性地解决传统方法难于解决的协同设计、高级参数化设计等关键问题。该项目成果具备良好的商业转化前景，并已在300余家单位和1700用户进行示范性应用。