ANALYSIS OF HOLONIC MANUFACTURING SYSTEMS BASED ON NON-ORDINARY COLLABORATIVE PETRI NETS

Abstract

Holonic manufacturing systems (HMS) provide a flexible and decentralized manufacturing environment to accommodate changes and to meet customers' requirements dynamically. HMS is based on the notion of holon, an autonomous, co-operative and intelligent entity able to collaborate with other holon to process the tasks. It enables the construction of very complex systems that are nonetheless efficient in the use of resources, highly resilient to disturbances and adaptable to changes in the environment. To perform a task in HMS requires a minimal set of holons to form a collaborative network. As individual holons may be unreliable, this adds complexity in modeling and analysis of HMS. How to dynamically form a minimal cost collaborative network for a task and analyze the effects of resource failures on the system operation are challenging issues. In this paper, we consider holonic assembly/disassembly systems with unreliable resource holons. We propose a Petri net to model a collaborative network and study its robustness. Robustness analysis concerns with the ability for a system to maintain operation in case of resource failures. Existing results on robustness analysis are developed based on ordinary Petri net models. However, non-ordinary controlled Petri nets have the advantages to compactly model assembly/disassembly systems where multiple identical resources may be required to perform an operation. This motivates us to propose a non-ordinary collaborative Petri net (NCPN) for this class of systems and extend the robustness analysis to NCPN.