A conceptual framework for holonic manufacturing: Identification of manufacturing holons

Future manufacturing systems will need to cope with frequent process distur bances and changes in production orders. Therefore, their control will requ ire constant adaptation and high flexibility. Holonic manufacturing is a hi ghly distributed control paradigm that promises to handle these problems su ccessfully. It is based on the concept of autonomous cooperating agents, ca lled "holons." This paper presents the conceptual framework that is needed for the development of holonic manufacturing systems (HMS). The paper defin es the identification task of the manufacturing holons as the first task in the development process and shows the role of a holon taxonomy herein. The holon taxonomy is based on orders, products, and resources as basic buildi ng blocks. They are structured using object-oriented design concepts like a ggregation and specialization. Additional staff holons provide the basic ho lons with specialized advice. The resulting architecture fulfills the requirements for holonic manufactur ing, where the autonomy of the agents provides the system with the ability to react to disturbances, while the existence of hierarchical control eleme nts provides the system with opportunities for global optimization. The res ulting architecture remains flexible, allowing control strategies ranging f rom very hierarchical to very heterarchical. A case study is given featurin g the PMA testbed HMS.