Fault-tolerant holonic manufacturing systems

This paper presents a model of fault‐tolerant holonic manufacturing systems (HMS) where each holon's activities are controlled by an intelligent software agent. Multiple agents schedule actions, resolve conflicts and manage information to produce, transport, assemble, inspect and store customized products. Our model provides robustness and distribution transparency across a shop‐floor where unpredictable failures occur with machines, control software and communication networks. Each autonomous holon is composed of a hierarchy of large‐grain functional components where interaction is carried out by user‐defined cooperation strategies. These strategies enable holons to coordinate their behaviour through exchanging messages and sensing/actuating of their shared environment. Therefore, holonic agents can select suitable rescheduling and recovery mechanisms to tolerate faults and keep the manufacturing system working. We also propose how the IEC 1499 standard (Function Block Architecture) for distributed control systems could be used to implement our model. The model presented here is a crystallization of some concepts from a generic cooperating agent system, with suitable extensions to meet the criteria of the ongoing HMS project. Copyright © 2001 John Wiley & Sons, Ltd.