Design Technology Research Of Product Assembly Based On Semantics In VRML Environment

Technology of product assembly is an important one in CAD research and application. This dissertation studies the virtual assembly technology, presenting a product-assembly-design theory and method based of semantics in VRML environment. Great progress has been made in the research of the key techniques of virtual assembly, which includes the assembly model layer level representation, abstracting the commonly assembly semantics, semantics decomposition and constraint mapping, semantics driving.Chapter 1 (the introduction) gives a review of the development situation in pruduct design process and virtual assembly research and application, while the open questions are also analyzed. In this background, the significance and contents of product-assembly-design method based on semantics in VRML environment are proposed particularly.Chapter 2 presents the assembly model layer level representation in VRML environment, points out assembly information distribution on the layer levels of this model. On the basis of the work, it introduces assembly semantics embracing engineering constraint and assembly handling, giving assembly semantics a formed definition and layer level representation.Chapter 3 investigates the content and major form classes of assembly constraint with description of semantics, bringing forth semantics' being decomposed and constraint mapping in order to turn semantics delegating of abstract and generalization engineering knowledge into geometric constraint.Chapter 4 puts forward the semantics driving way of VRML system based on analyzing basic process, winnowing and stipulating the degree of freedom, coming into possession of algebra expression of geometrical constraint, holding forth the concept of beforehand assembly, actualizing the semantics drive with assembly constraint identification and assembly position solution method.With the theory and methods in this dissertation, chapter 5 introduces the environment of VRML system, coming up with some examples of semantics assembly.Finally, conclusions were drawn from this dissertation with recommendation for future research in chapter 6.