Research On The Key Technologies Of Formal Design For Product Scheme

This dissertation presents a new theory and method of formal scheme design based on the characters of design information, such as abstraction, fuzziness and hierarchy. The emphases in the dissertation are the key technologies in motion scheme design, assembly scheme design, configuration design and scheme reusing. The successful applications in several research projects have proved the utility, flexibility and power of the theory, method and software proposed in the dissertation.The main work of the dissertation is as follows:Chapter 1 gives a review and history of the development situation of product scheme design, analyzes the inevitability of formal scheme design. The background and contents of formal scheme design are also proposed particularly.Chapter 2 puts forward several basic principles for formal scheme design, analyzes the formal design steps for diffent kinds of product schemes, and proposes design language and deduction methods for formal scheme design.Chapter 3 puts forward a hierarchical formal model for motion scheme design. The model is composed of three levels, namely motion function, mechanism mapping and mechanism combination. The level of motion function realizes the abstraction expression of design process and complex motion relationship by character symbols. The level of mechanism mapping realizes the evolution from character symbols to mechanism symbols, and from mechanism symbols to assembly symbols by the mapping of motion function to mechanism and the mapping of motion relationship to mechanism combination. The level of mechanism combination realizes the visualization of motion scheme by the combination of assembly symbols.Chapter 4 puts forward a formal method for assembly scheme design. To obtain assembly constraints from functions automatically, the dissertation puts forward a mapping method from function to assembly semantics, and assembly semantics to assembly constraint. Assembly semantics is assembly expression that accordant with engineer's design habit. The mapping method includes two steps: one is the mapping from function to assembly semantics; the other is the mapping from assembly semantics to basic assembly constraints that easy to handle with computer. The assembly sketch is obtained by the combination of assembly symbols.Chapter 5 puts forward a formal method of configuration design. The composition, attribute and relationship of template symbol and node symbol are researched, and an optimization model of configuration design based on template symbol is put forward. A variable design method based on template symbol is researched. The relationship of product version evolution and template symbol evolution is analyzed.