In this paper we examine an approach to the visualization, analysis and design of functional shape interactions represented as motion constraints in configuration space. A graphical constraint representation, together with a set of computational tools we have developed, permits a designer to visualize and directly manipulate motion constraints in order to achieve desired functional properties. The resulting system has been implemented and applied to the analysis and design of a set of orienting, fixturing and assembly devices for the automated assembly of planar parts.>

The authors illustrate the need for planning in assembly and describe a set of modeling and planning techniques developed to generate robust force-control strategies for a certain class of assemblies. Specifically, they develop strategies for the chamferless insertion of a planar peg into a hole and the insertion of a three-dimensional rectangular peg into a rectangular hole. The complexity of applying these techniques in three dimensions is also discussed. It is seen from the analysis of the insertion of a planar peg into a chamferless hole that there are cases where an assembly may not be reliably carried out if the contact configurations between parts are not constrained. In such cases it is necessary to a priori specify the configurations through which the assembly must pass, and guarantee that only those configurations are encountered. From the analysis for the insertion of a three-dimensional rectangular peg into a chamferless hole, it is seen that for moderately complex assemblies involving may possible configurations, the specification of a set of configurations through which parts must pass is considerably more difficult than for the planar case. However, by considering only a subset of the possible configurations chosen on the basis of a set of heuristics, successful assembly strategies can be generated.>