Minimal infeasible sets of connections: a representation for efficient assembly sequence planning

This paper describes methods aimed at increasing the efficiency of cutset-based assembly sequence planners by: (i) providing an alternative representation to precedence constraints which is easy to maintain and facilitates the logical evaluation of assembly operations, (ii) maximizing the reuse of previous results of assembly operation feasibility evaluations and (iii) using exact and heuristic assembly knowledge encoded in a knowledge-based system, which may provide time saving shortcuts to the direct use of geometric algorithms. It is formally proved that in this method it is sufficient to evaluate directly the assembly operations corresponding to the decompositions of a product in its completely assembled state for the generation of all assembly sequences of a product. The feasibility of any other operation, that may be performed in the assembly of the product, can then be logically inferred from these evaluation results. A simple and well known assembly is used to illustrate the application of the approach and facilitate a comparison with other methods.