Towards modelling of assemblies for product design

Abstract

Current cad systems provide exhaustive capabilities for specifying detailed component geometry in support of the product-design process. However, before detailed geometric designs are finally produced, the designer must first map the product requirements into functional specifications, and realize the functional specifications in the form of conceptual designs. While it may not be possible to automate these more creative steps fully in the design process, cad systems can support the design process better, by consistently representing and maintaining the functional intent of the designer. To provide such support, the cad systems must address the assembly level, since only at this level is it possible to model the functionality of the design in terms of the functionally significant geometry and assembly relations. The literature survey first establishes basic information requirements for a cad framework in support of the broader design process. The literature is reviewed in the context of this framework. The following areas are reviewed: the choice of modelling primitives for the specification of assembly information, the choice of various model structures for the aggregation of the assembly information and the use of this information for design analysis, and the choice of strategies for relative part positioning for the computation of the final assembly configuration. Even though research is well developed in individual aspects of assembly modelling, there are major gaps that must be addressed before cad systems can make use of assembly modelling as an integrated framework for product design.