Research Of Collaborative System Based On Heterogeneous CAD Platform

Integrated with the CAD technology and CSCW technology, the collaborative CAD, which is able to shorten the product development time, make best use of remote resources and reduces the design cost, has made a rapid and further progress in the past decade. The collaborative design between heterogeneous CAD systems is an important aspect for research. The collaborative design within heterogeneous CAD systems becomes a significant challenge because of the great difference between the modeling operations and underground data structures of different systems. In order to enable it, This dissertation mainly deals with collaborative system based on heterogeneous CAD platform and some related key technologies.The product model is very important for the collaborative system based on heterogeneous CAD platform. A product modeling technology based on neutral modeling command is developed in this paper according to the product modeling technology with parameter: one is the orient object technology, to express the neutral modeling command with class and object, the other one is using the topology category of topology type directly and the geometry information of the topology category in the world coordinate to express the boundary topology category. The technology solve the problem of indication of product modeling of the collaborative system based on heterogeneous CAD platform.A design history-based direct incremental transmission algorithm is developed in this paper according to the requirement of real-time transmission of accurate CAD model in collaborative modeling systems. The incremental model is expressed in means of changed primitives. Changed primitives is composed of the topological elements changed in one of modeling operation which can be classified to added elements, deleted elements and modified elements. The algorithm makes use of identifying mechanism of entities to maintain and update the solid model. The paper gives the methods of determining, coding and transmitting changed primitives and solves the problem of reconstructing the result model correctly.Empl- ing this method may greatly reduce data transferred among the collaborative sites and make collaborative design effectively.A collaborative information exchange method is proposed to realizing the collaboration awareness, This method reduces the data flow of network transmission. The structure of knowledge base is established by Meta Data Services in Microsoft SQL Server 2000. The TCP/IP protocal and socket procedure are used to implement the data network commtmication.On the basis of the theories and the methods above-mentioned, the collaborative system based on heterogeneous CAD platform is developed in the SolidWorks and Pro/E environment by utilizing Visual C++ and Visual Basic. Some functions, including the management of members and control power, the expression of the product model, the incremental transmission of the model data, the information exchange between the collaborative members and so on, are realized in this system. Living example shows the theories and the methods proposed in this paper are correct and has strong practicability in collaborative product modeling.