Automatic identification of geometric constraints in mechanical assemblies

Mechanical assemblies of manufactured components involve sets of relations between mating surfaces and functional characteristics. Components must fit together to assemble and function properly, placing constraints on the allowable values of the component dimensions. Kinematic motion of the components is often necessary, resulting in other geometric constraints. Identification of constraints in models of mechanical assemblies is necessary for simulations of the effects of dimension and tolerance changes. This paper presents techniques for the automatic identification of such constraints in computer models of three-dimensional assemblies with nonorthogonal contacts between component surfaces and kinematic joints. The approach relies on a graph-based representation of the assembly. Search algorithms for identifying assembly constraints in this graph are presented. (C) 1998 Elsevier Science Ltd. All rights reserved.