Research On Theory And Technology Of Heterogeneous CAD Collaborative Design Based On Cellular Ontology

As a kind of advanced product paradigm in network economy and knowledge economy environment, collaborative design among heterogeneous CAD systems emphasizes inter-enterprise collaboration and information sharing in the whole society. The goal of collaborative design is to improve the innovative capability and to realize the lower cost and higher efficiency of product designing. However, the data are stored by different storage methods among heterogeneous CAD systems, and defined based on different concepts, attributes and relations, which results in the heterogeneity of data source, and brings to difficulties of collaborative design.The characteristics of semantic feature modeling and the theoretical results of collaborative design based on the home and aboard are analyzed adequately. Computer technology, ontology technology and the other related technologies are applied in collaborative design to resolve the problems of incomplete semantic information of CAD modeling, low transmission speed of shared modeling data, concurrency conflict and so on. This study includes the following contents:Firstly, to realize the goal of widely distributed and heterogeneous CAD system share and integration, a collaborative resource share approach based on cellular ontology is proposed. The building method of cellular ontology is discussed in detail. The cellular ontology is composed of three parts: cellular model, sharing ontology library and semantic inference model. The cellular ontology provides the basis for unified representation and data exchange of heterogeneous semantic information and implements to dynamically acquire the semantic information of feature modeling. Based on the proposed framework, a application case is implemented aiming to provide semantic interoperability between heterogeneous CAD systems and richer collaborative resources for enterprises.Secondly, to solve the problem of high data transmission quantity of shared CAD model in synchronized collaborative design, a hierarchical data transmitting method based on feature face is proposed. By this method, only the triangle facet information is transferred first, the feature faces of components, which would be assembled , would be specified when that parts are to be collaborative assembled, and send all semantic information of the special feature face. For extracting any feature face in a short time, the architecture of sematic feature modeling is expanded four-level structure: feature dependency graph, feature face model, cellular model and facet model. This method reduces data transmission quantity of shared model, and improved transmission speed.Thirdly, conflict is unavoidable in synchronous collaborative design, a conflict resolve method based on feature precedence relation is proposed. The static priority of designers is made based on role mechanism. The feature dependency relation of feature modeling is summarized. Dynamic priority of feature operation is made based on feature dependency relation. The combination of the two can effectively detect and resolve conflict, maintain consistency of the models.Fourthly, the similarity of part and assembly is analyzed. Based on the analyses, a uniform collaborative virtual assembly environment is proposed. Collaborative assembly relation model is developed to represent assembly relations in a semantic feature modeling. In collaborative assembly relation model, high-level assembly concepts and relationships among those concepts are defined, the assembly knowledge has been classified into a hierarchy of assembly concepts. The assembly information is dynamically acquired based on collaborative assembly relation model, and implicit constraint relation is acquired too. The collaborative assembly of parts and components are realized among heterogeneous CAD systems based on this framework.At last, the prototype system of synchronous collaborative design is developed based on the above-mentioned key technologies and computer program technologies such as KAON、VC and SQL Server database, and the feasibility and efficiency of the platform is proved.