Research On Collaborative Design In Heterogeneous Environment And Its Application In Automobile Product Design

The globalization of modern manufacturing, especially in automobile industry calls for CAD technology focusing on collaborative CAD based on heterogeneous environment. Based on systemic summarizing production up to date, this dissertation deeply researches some key technology in the domain. Mainly content are:Basic meaning, architecture and correlative key technology of collaborative CAD system in Heterogeneous environment are discussed systemically. By utilizing the advantage of centralized and replicated system, composite collaborative CAD system is established. Furthermore, the key problem of CAD model exchange method between Heterogeneous CAD Systems based on feature, CAD model representation, transmission mechanism, and message route and treatment are researched in the dissertation.According to analysis of feature-based commercial CAD systems, framework of data exchange based on implicit and incremental feature is put forward and based on it, standard feature library is established. Furthermore, feature element, feature structure, feature history and feature coordinate are discussed in detail. To satisfied demand of car body design, geometry-based surface representation is put forward according to the method of previous investigator.Directly referring to topological entity of B-Rep domain in feature's parametric definition domain is inherent limitation of previous persistent naming topological entity method. A feature-based solution for topological entity naming is proposed in this paper. Firstly, uniform naming method for feature face is established and its name is remaining invariable during the modeling procedure. Secondly, the expression between topological entity and feature face is established and topological entity expressed by feature face is referred during the course of feature's parametric definition, and as a result, solve the problem of persistent naming topological entity for feature-based collaborative CAD. Thirdly, the concept of reference face is proposed and utilized to solve ambiguous referring problem, which arose from topological face splitting, topological edge splitting and multiply intersection edges. Based on above researches, topological face and topological edge matching method is discussed in detail. By analyzing the characteristic and deficiency of previous concurrency control of replicated collaborative CAD system and deeply researching complicated relations of features, the definition of concurrent conflict is presented in collaborative design system. The method of concurrency control taking feature as unit is proposed according to spatial and reliant relation between CAD features and concurrency control mode which is fit for replicated cooperative design system is designed. According to Practice requirement, low-coupling with local CAD system function module is also designed.Take account of product database system, the mappingEXPRESS-definitions into relational database system structures is researched firstly in this dissertation. The rules for mapping the data type defined in STEP standard to relational database system, including primitive type, naming type, aggregation type, structural type, and the relations between different types such as simple or complicated inheritance and reference. Secondly, aim at three representative access mode Navigational, Existence-dependent and mixed mode, take Part Identification, Bill of Materials and Part Geometry as example, corresponding data access method are presented. Lastly, as an application example of product database, a bridge for exchange information between AP214 and AP224 is designed to implement CAD/CAE/CAM integration. The procedure for extracting feature information form AP214 product database is discussed in detail. Based on the research mentioned above, system prototype is developed utilizing Visual C++ programming language and ST-Developer which is STEP development tool.Collaborative view triangular-surface model among different design teams is realized by using interface of CAD software. Firstly, original triangular surface is obtained form VRML file. Secondly, in order to capable of view original CAD model more approximately, method of constructing G~1 continuous triangular B-B surface and mesh subdivision after the vertex consistency problem is solved.