Research On The Theory,Method And Application Of Product Information Symbol Modeling

Product information modeling is the foundation of product design activity. According to the characteristics of product design information and design process, this dissertation presents the principle and method of product information symbol modeling on the basis of unit modeling, investigates the key technology of product conceptual scheme modeling, assembly relationship modeling and detailed structure modeling based on symbol model, and a symbol modeling prototype system is developed.The main work of the dissertation is as follows:Chapter one reviews the current research situation of product information unit modeling, analyses the existing problems, and addresses the significance and contents of the dissertation.Chapter two presents the basic principle and method of product information modeling based on symbol. With the analyses of the unit characteristics of product design, the symbol is defined to describe the design object and relevant information, and its content, form, characteristic, classification, coding and database are studied. The structure of symbol model and its construction, variation and reconstruction are discussed, and the product design process based on symbol model is marked out. Taking the symbol as the product information carriers and basic elements, the symbol modeling realizes the information description with formalization, abstraction and integration, expresses the product design process with symbol model evolution, and offers the new theory and method for product development.Chapter three presents the product concept scheme model based on the function and structure characteristics of symbol. The internal relationship between function information and structure information of the design objects is established with the symbol integration, the function resolution symbol model and the structure scheme symbol model are presented. The conceptual design process can be divided into three levels for dispersing the design object according to function resolution, thus the structure scheme can be obtained to meet the function requirement with the function-structure mapping. On applying symbol modeling principle to product conceptual design, the limit of geometry expression is avoided, and the innovation and abstract requirement of product concept modeling is fulfilled.Chapter four presents the product assembly relationship model based on the symbol correlation. The concepts of mating face and mating couple are defined, and the assembly relationship of solid level and face level is described with assembly constraint and mating constraint respectively. The assembly constraint symbol network model and the mating constraint expanded symbol network model are established. The dynamic construction of assembly model, dynamic loading of constraint information, part localization solving, the refinement and variation of assembly constraint, and the model reconstruction are also studied. The assembly model based on symbol correlation describes the assembly constraint and design process in formalization, and facilitates the product structure reconstruction.Chapter five presents the part structure model based on the unit symbol. The conception of unit symbol is defined; its internal and external structure feature and the correlation between them are also described. The part model based on the structure correlation constraints of unit symbol is established, the dynamic modeling process is studied, and the structure variation design and parameter variation design are implemented. As the structure information carrier, the unit symbol improves the description level of structure information, facilitates the construction and variation of product structure model, and offers an effective method for enhancing the efficiency of part structure design.Chapter six studies the recognition technology for product information in engineering drawings. The cell is presented as the basic unit to describe the technology information form, and the correlation constraint between cells and between forms is analyzed. The standard form is established for recognizing and writing the form information to database through matching method, and the database provides data support for product symbol modeling.Chapter seven introduces the product design prototype system based on the symbol modeling technology, lists the architecture and main components, and demonstrates the applying of symbol modeling technology in product design with some examples.Chapter eight summarizes the research work in the dissertation, and suggests the further research direction.