【作者】 晏强；

【导师】 李彦；

【作者基本信息】 四川大学 ， 机械制造及其自动化， 2003， 硕士

【摘要】 本课题来源于国家自然科学基金(50075058)资助项目“基于过程的计算机辅助设计模型、拓扑结构和原型系统(A Process-based CAD Model and Prototype System)”。 在工程领域，日益增强的市场竞争对产品功能、质量、开发周期等提出了更高的要求。一个新产品的设计过程是一个包括了许多复杂推理及做出决定的过程。任何设计总是从需求出发，而不是从几何或者图形出发，图是设计的结果，而不是出发点。但现有CAD软件很大一个弱点在于是以图为设计的主体，从一开始就画图，仅能描述设计过程的最终结果，即几何详细设计阶段，而不能描述整个设计过程。从一个CAD文件只知道这个产品(PRODUCT)的数据，不能知道它的设计过程(PROCESS)数据。 本文就现代设计技术和现代CAD技术做了一些研究，建立了一个基于整个产品设计过程的计算机辅助设计模型和方法，并完成一个软件原型系统。它支持整个产品设计过程，即需求描述、概念设计、结构设计、详细设计和生产计划等，能支持设计者创建、分析、评价和选择他们的创新设计概念，能结构化设计数据和知识，并能支持设计团队的协同工作和基于网络的分布式设计工作。 本文提出的基于过程的计算机辅助设计理论模型—PCAD模型，其核心是关注整个设计过程的活动和任务，以及它们之间的逻辑关系。该模型并不是告诉设计者怎样设计，而是辅助他们设计并帮助他们管理、优化整个过程，以达到提高产品质量、降低产品开发成本、缩短开发周期，从而提高产品竞争力的目的。PCAD模型覆盖了整个产品设计过程，有助于繁杂问题的处理及跨平台和分布式的运用。PCAD模型由五个核心模块组成:设计矩阵、功能方法树、产品结构树、IDEF3、设计数据模型。 在PCAD理论模型的基础上，采用JAVA+XML作为开发工具实现了一个原型系统。PCAD原型系统的核心问题是利用计算机实现对整个设计过程的支持，并实现设计数据的重用，同时保证系统的平台无关性和数据的独立性，便于建立协同设计和分布式设计的平台。系统采用面向对象的程序设计方法完成各功能模块的设计，重点在于支持产品设计过程，实现设计数据模型及应用系统与XML文档的数据交互。系统采用XML文档结构化存储设计数据，具有良好的通用性和扩展性，便于在网络上的传输。定义了存储设计数据的XML文档的模板CellDatadid，规范XML文档的结构。PCAD原型系统并不是要建立一个新的类似于Pro/E，AutoCAD传统意义上的辅助设计系统，它重在对于设计过程的支持，是从产品设计的起点即需求分析出发，结合现有的一些CAD工具辅助设计者完成产品设计。 PCAD软件原型系统已初步建立并验证了理论模型的实用性。系统以工程形式来管理一个产品的设计过程，能够创建和管理功能方法树、产品结构树，建立设计矩阵，结构化存储设计数据。在设计矩阵单元中，设计者能够采用草图、文本、图片等多种形式和第三方工具软件一记录产品设计过程。 目前，只是初步完成了原型系统的开发工作，还有大量的工作需要在进一步的研究中完成。更多还原

【Abstract】 The Project is "A Process-based CAD Model and Prototype System" which is supported by National Natural Science Foundation(Grant No. 50075058 ).In order to remain competitive of products, new approaches in the field of mechanical engineering are needed to improve the effectiveness and efficiency of the design process. The design process of a kind of new product is a process that involves much complex reasoning and determination. Any design always starts out from requirement but not from geometries. The geometries are the result of design but not start point. However, CAD systems in existence have a big weakness, which is that they regard geometries as main body of design. They start from drawing and only can describe final results of design process, i.e. geometric detail design stage, but not whole design process. Designers just can know product data from a CAD files but cannot get design process data.Based on research of modern design technology and CAD technology, this paper presents a process-based CAD model and approach which can support whole product design process, i.e. requirement description, conceptual design, structural design, detail design and production plan. The model and approach is able to support generation, evaluation and selection of designer’s concept, to capture and structure the design data and domain knowledge, to support coordinating and distributed design based on Internet.At present, CAD systems cannot entirely support product design process. This paper presents a process-based CAD model, PCAD model, which focus on activityand tasks of design process and logical relationship between them. The model does not tell designers how to design but aid them designing and help them manage and optimize design process, to the effect that improving product quality, reducing product development cost, shortening development cycle and raising product competitive. PCAD model covers whole product design process, and it is developed by using the blackboard-based technology to combine the design matrix, function-means tree, product tree, IDEF3 model and third-party software tools. It is helpful to handle complex problems and build distributed application that is platform independent.According to PCAD theory model, the author develops a software prototype system using Java and XML. The core of the prototype system is to apply computer to support whole design process and achieve reuse of design data. Meanwhile, the system is platform independent and data is independent, so that coordinating and distributed design platform can be built. The PCAD system adopts object-orient programming method to design each function module. Its emphasis lies in supporting product design process, achieving Design Data Model and data exchange between system and XML files. XML files are used to store product design data. It has good universal property and expansibility and is easy to communication online. The paper defines CellData.dtd, the template of XML files, to standard the structure of XML files.PCAD software prototype system has been built in the main and verified the practicability of the theory model. The system manage design process of a product with project mode, and can establish and manage function-means tree, product tree and design matrixes to store structurized design data. In the cells of design matrixes, designers can use sketch, text, picture, and the third party software tools and so on to describe product design process.At present, the prototype system is just completed in the main, so there is still lots of work to be do in the further development.更多还原