Automatic derivation of transition matrix for end-of-life decision making

Abstract

Recently strengthened environmental regulations have obligated manufacturing companies to treat end-of-life (EOL) products both environmentally consciously and economically. EOL treatment begins with disassembling a product into recyclable or disposable sub-assemblies. Therefore, the economic value of an EOL product is largely a function of the plan for its disassembly: the means by which it is to be disassembled into smaller sub-assemblies, and the choice of sub-assemblies to be disassembled first. In order to make these decisions, a disassembly structure describing every possible sub-assembly division and its disassembly path from the original product has to be presented in a typical form. A widely used form of such a structure is a transition matrix. A transition matrix shows all feasible sub-assemblies and their disassembly hierarchy. Whereas it can be easily transformed into mathematical disassembly planning problem, the tedious work required for its generation limits its practical use. In this paper, we propose an algorithm for automatic derivation of a transition matrix. The proposed algorithm provides an efficient way to derive a transition matrix based on a product's architectural information, which includes the product's physical connections and the relative geometric locations between individual parts. The algorithm was validated in deriving a transition matrix of a car door-trim. Our algorithm can significantly expand the applicability of transition-matrix-based disassembly planning research.

Keywords:

• end-of-life treatment
• disassembly planning
• transition matrix
• product architecture
• connection graph
• precedence graph

Acknowledgements

This work was supported by a Korea Research Foundation Grant (KRF-2005-042-D00360) funded by the Korean Government (MOEHRD). The authors would like to express special thanks to the Engineering Research Institute (ERI) of Seoul National University for its administrative support during the project period, as well as to Hyundai Motor Company for their cooperation.

Notes

Note

1. P(S) and C(S) are used to denote a set of parts and joints of sub-assembly S, respectively.