An Ontology Approach to Product Disassembly

In recent years, growing ecological concern has prompted for ‘design for environment’. One way to achieve this is to design products that are easy to disassemble, because this improves the ability to reuse or recycle parts of a product. This paper presents a computational theory for product modeling and reasoning about product disassembly. This theory, implemented in the PROMOD system, is based on an ontology of different connection types between product components. For the task of reasoning about disassembly, the standard topological relation that expresses that two objects are connected or in contact proves to be inadequate. We therefore introduce, within a topological context, a small number of new ontological primitives concerning the rigidness of connections and the constrained degrees of freedom, which in effect are task-oriented abstractions of geometric and physical-chemical properties of products. On this basis, it is demonstrated that one can automatically generate all feasible product disassembly sequences, and in additionperform an ecological costbenefit analysis. The latter provides a preference order over disassembly sequences, allowing to compare alternative product designs for recycling and reuse. Finally, we show how the proposed ontology for disassembly is an extension of existing ontologies dealing with physical systems, and is based on the same ontology design principles. This work has been carried out as part of the SUSTAIN project, with PRé Product Ecology Consultants and ECN as partners, and partially supported by the SENTER-IT Programme of the Netherlands Ministry of Economic Affairs. Helpful discussions with Mark Goedkoop (PRé) and Jan Braam (ECN) are acknowledged. We also thank Mark Goedkoop for kindly providing us with the coffee machine which we have thoroughly disassembled for the purposes of the present study.