Study On The Theory And Method Of Virtual Assembly

Facing violent market competition, how to push the new product into the market with the fastest speed and occupy the market rapidly is the key to the survival of the enterprises, for this reason, the scholars over the world have put forward many new product developing strategies, produce modes and advanced manufacture technologies. But these strategies, modes and technologies can not dispense the process radically that the prototyping has to be manufactured again and again during product development. The main reason of this is that the problems about assembly and maintenance in product design can only be exposed during manufacturing or after sold, therefore the virtual reality technology was applied to product assembly design and the virtual assembly was emerged. Since the virtual assembly technology can merge the assembly engineer's knowledge and experience into product assembly design, that the assembly engineer can make reasonable evaluation to the product assemblability and disassemblability at the early stage in product design, and the virtual assembly technology was welcomed deeply by the enterprises. But as far as the virtual assembly technology is concerned, it is a kind of new technology, the theories and techniques about the virtual assembly technology are all immature and the virtual assembly technology lacks relevant standards. Although the virtual assembly technology has been applied in motor and airplane enterprises and preliminary achieves have been made, these application lack the support of the relevant theories and techniques. So this thesis will analyze and study the relevant theories and techniques of the virtual assembly technology deeply. The contents and achievements are the following:â‘ In order to apply the virtual assembly technology to the enterprises, the reform of the design methods in manufacturing industry, the importance of the DFX design methodology in product design and the position of the virtual assembly technology in product design was analyzed. Based on the discussion of the custom demand on the virtual assembly system, the four-layer structure of the virtual assembly system, including data interface module, user interface module, virtual assembly environment module and data output module, was put forward. And the applying process of the virtual assembly technology in product development was advanced.â‘¡The problems of the virtual component model in virtual assembly system was analyzed, that is, the design information was loss when the component model was imported from CAD system into the virtual assembly system which makes it difficult for the assembly engineer to capture the assembly constrain relation between parts in virtual environment. Aiming at these problems, the mapping mechanism between the virtual model and the CAD model of the component was put forward. The assembly relation incarnated in geometry feature was mapped onto the virtual component via this mapping mechanism, therefore the assembly engineer can capture the assembly relation rapidly in the virtual environment. Based on this, the assembly method based on assembly relation was advanced, that is, while modeling the product, the assembly engineer can analyze the component size and tolerance, and choose suitable assembly method and assembly tool according the characteristic of the tolerance, and then the assembly sequence was generated. At last the record and store method of the output information of the virtual assembly system was studied.â‘¢The fault of the traditional interactive manner based on two dimensional metaphors and the characteristic of the interface between human and computer in virtual environment was analyzed. In order to overcome the contradiction between the space unlimitedness of the virtual environment and the space limitedness of the place producing the virtual environment and the difficulty of operating objects in the virtual environment, the virtual assembly technique based on the gesture command was advanced, according to the hand's anatomic structure and the principle of the...