Development of an Ontology for the Automatic Reconfiguration of a Vise-Type Fixture Device

Abstract

The need for reconfigurable manufacturing systems has long been recognized as a key factor to gain the necessary flexibility for economically producing customized products. Automation of the reconfiguration processes is a challenge both on the hardware and the software level. Addressing this issue in the field of fixture design, a new reconfigurable fixture device for a CNC milling machine has been developed. The developed vise contains interchangeable jaws enabling the secure fixture of a wide variety of workpiece geometries. To enable automated reconfiguration, a reasoning system is needed that can determine feasible fixture configurations based on the given workpiece and part as well as the available fixture components. In this paper, an ontology for representing fixture design and reconfiguration knowledge for a specific reconfigurable vise-type fixture is introduced. The creation of the ontology is based on a systematic building methodology to identify necessary concepts, attributes and relations within the domain. Using Description Logic as the representation formalism, core concept definitions and relations are formalized to evaluate the correctness and consistency of the ontology. The ontology is validated both on the informal and on the formal level by its ability to find feasible fixture configurations, i.e. appropriate jaw pairs to fix example workpieces. The paper concludes with a discussion of the results and future work.