SHEET METAL BENDING OPERATION PLANNING : USING VIRTUAL NODE GENERATION TO IMPROVE SEARCH EFFICIENCY

Abstract A large number of manufacturing operation planning problems can be formulated as state-space search problems. In the case of sheet metal bending operation planning, processing a search node involves extensive geometric reasoning. Computation-intensive node processing limits the number of search nodes that can be expanded in a reasonable amount of time, making it difficult to solve real-life operation planning problems. This paper describes a scheme to speed up operation planning by virtual generation of state-space nodes. Unnecessary computation is eliminated at the time of node generation by extracting the required information from already generated nodes. Although generation of two different search nodes rarely involves identical computation steps, there is considerable overlap. The node generation step is divided into a number of computation subproblems. When a new node needs to be generated, one can check if any of the subproblems have been solved for any of the already generated nodes. If any subproblem has already been solved for some other node, then the solution is used to save computation time. In such cases, computation steps are not performed; therefore, such node generation is called virtual. The scheme presented in this paper increases the node generation capability and consideration of many more search nodes. The ability to consider more search nodes helps in solving more complex problems and finding better operation plans.

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