Research On Some Key Problems Of Multidisciplinary Collaborative Design In Network Environment

With the increase of the market pressure, product design is more and more becoming a collaborative task among the designers in different disciplines distributed geographically. By synthetically considering all disciplines' performance requirements on product as well as coordinating and solving the conflicts among the disciplines the development cycle and cost can be reduced and product quality improved. However, traditional CAD tools have failed to satisfy this requirement, so a new network-based multidisciplinary collaborative design (MCD) system needs developing. In the domain of product design, from the view of product design theory and method, some key problems of MCD are studied in this thesis, and the thesis also makes creative explorations on the theory, method and practice of MCD.Firstly, on the basis of the analysis of characteristics of MCD, some new concepts such as three-dimension framework of MCD, discipline view and product discipline model etc. are proposed. The multi-levels' relation of function, behavior and structure among many product discipline models is analyzed, and the formalization description of multidisciplinary collaborative design problem is given. Thus, the foundation for theoretical study and implement of MCD in this thesis is established.Then, a new MCD-oriented product information model that merges design semantic, physical structure, collaboration, relation and constraint data is put forward. An extended object-oriented method is introduced to represent the product model, by which, the product model can be defined recursively without a pre-defined granularity, and can be easily extended transversely and lengthwise, and thus has good flexibility and evolution ability. The class inheritance mechanism under network environment is studied, and the methods to build the product discipline model are given.A multi-level constraint and relation net model about function, behavior and structure is put forward, along with the corresponding approaches to realize the coordination and consistency maintenance among many product discipline models by synthetically using the design semantics, relation, restriction and collaboration management information. The principles and methods based on the semantic reasoning to realize the static and dynamic coordination among multiple discipline models are discussed. Aiming at the problems such as the concurrent operation, the dead lock and the consistency maintenance in the solving process of distributed constraint network of multidisciplinary collaborative design, a time-based lock-adding algorithm is put forward to resolve all the problems above. A strategy locking constraint resource by using "write-lock" and "read-lock" is presented to consider the time delay of data transmission and improve the efficiency of concurrent operation, which is added by the corresponding lock-adding algorithm.The functions such as collaborative browse, control, modification and service, etc of product geometric model among multi disciplines are realized by using VRML, Web technology, redeveloping technology of Pro/Engineer and middleware technology, etc synthetically. Aiming at the semantic mismatch problem in MCD, the thesis suggests a sort of multi-level semantic communication model; develops a communication language used for multidisciplinary semantic negotiation which is developed based on XML; sets the open action original language set and the open message type template library; and builds a shared ontology library based on OWL to promote the consistent understanding of common conception among the designers in different disciplines.After the negotiation characters of MCD is analyzed, a negotiation framework and a negotiation strategy is put forward, the latter is used to make the union satisfaction of the overall goal maximum on the premise of guaranteeing the satisfaction level of every discipline's local goal. Utilizing the game theory, a formal description to the negotiation strategy is made, and the corresponding negotiation model used for MCD is generated. On the base, a negotiation management system is developed for supporting the negotiation process among the disciplines. Through synthetically considering and weighting the suggestions of each side, a recommend scheme is given by the negotiation management system, which can assist the different discipline designers rapidly reach a consistent product design solution.Based on the above research results, a multidisciplinary collaborative design prototype system (MCDPS) is developed, which consists of the distributed discipline modules, the distributed component libraries, the distributed calculation resource libraries and the management modules, and has such characteristics as distribution, openness, concurrency and flexibility. By means of MCDPS, the design of the automobile clutch is carried out. The case study indicates that the proposed methods are feasible and effective.