| A method is presented which allows a designer to interactively create an assembly of components by specifying geometric constraints between individual components. Lower kinematic pairs are implicitly defined through the explicit definition of geometric constraints. Upon establishing lower kinematic pairs, or joints between several components, a spatial mechanism begins to take form. The spatial mechanism may consist of one or several open and closed loops it may also contain both serial and parallel chains. Regardless of the composition of the spatial mechanism, the designer is free to add, delete, and edit components and joints in the mechanism, as well as grab and drag components to new positions. All is done while maintaining previously defined geometric constraints automatically.To achieve this freedom and flexibility in mechanism assembly, two areas of work are presented. The first is the development of an assembly representation that establishes connectivity between components in a hierarchical manner. The second is the development of an algorithm which automatically maintains all geometric constraints whenever the assembly is modified. The assembly representation and geometric constraint algorithm developed in this work are mutually exclusive--both stand alone on their own merit. Yet combining the two yields a robust Computer-aided design (CAD) tool which allows the designer the freedom and flexibility to explore a myriad of assembly designs without sacrificing complexity and time. The intent of this work is to give the designer an unencumbering CAD assembly tool which serves as a front end to subsequent analyses. Providing a front end assembly tool will promote the exploration of several design alternatives, thus yielding the best design artifact prior to submission to more extensive and costly analyses. |
