Jozef Wyns

Holonic manufacturing systems

This chapter presents the earlier results in our development of a holonic manufacturing systems framework, with a clear emphasis on manufacturing and logistics. The insights discussed in the previous chapters were used as precious guidelines and as a check for soundness when comparing options. In particular, design for the unexpected (low and late commitment) and maximizing the potential for achieving critical user mass were important factors influencing the choices made during the development activities.

A conceptual framework for holonic manufacturing: Identification of manufacturing holons

Future manufacturing systems will need to cope with frequent process disturbances and changes in production orders. Therefore, their control will require constant adaptation and high flexibility. Holonic manufacturing is a highly distributed control paradigm that promises to handle these problems successfully. It is based on the concept of autonomous cooperating agents, called “holons”. This paper presents the conceptual framework that is needed for the development of holonic manufacturing systems (HMS). The paper defines 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 building blocks. They are structured using object-oriented design concepts like aggregation and specialization. Additional staff holons provide the basic holons with specialized advice. The resulting architecture fulfills the requirements for holonic manufacturing, where the autonomy of the agents provides the system with the ability to react to disturbances, while the existence of hierarchical control elements provides the system with opportunities for global optimization. The resulting architecture remains flexible, allowing control strategies ranging from very hierarchical to very heterarchical. A case study is given featuring the PMA testbed HMS.

Designing Holonic manufacturing systems

Abstract This paper discusses the design of Holonic manufacturing systems (HMS), with emphasis on manufacturing control. First, it discusses the concept of a Holonic system. Second, it presents the HMS reference architecture for manufacturing control. Third, it addresses the overall design problem, i.e. designing both the holonic control system and the underlying manufacturing system. Finally, the paper addresses the design and development of the control software itself.

Planning systems in the next century ( II )

Abstract This document is the second part of two papers that present a vision on planning systems for the 21st century. Reflecting the research background of the authors, the focus of this second part is short term planning and plan execution, including shop floor control, whereas the first part addresses medium and long term planning, e.g. MRP. Current IT support for planning and plan execution enables to master huge amounts of data. However, these IT systems reduce the ability of the overall manufacturing system to adapt and evolve when this requires IT system maintenance. This paper presents five vision statements on future planning systems that contribute to the ability to adapt and evolve: multiple hierarchies, early return, order agents using advice, embedded simulation, and allowing redundant functionality.

Holonic Manufacturing Control at K.U. Leuven

Abstract This paper presents an overview of ongoing research on Holonic Manufacturing Control at the PMA division of the K.U.Leuven. First, it discusses the term Holonic System. Next, it describes the Holonic Manufacturing Control Architecture. Third, the paper discusses a functional decomposition of the control system design. Finally, implementation issues are addressed

Resource allocation in the holonic manufacturing system at K.U.Leuven

Abstract Dynamic resource allocation is an important task within next generation manufacturing control systems. Since the problem is crucial to the correct functioning of the manufacturing system, a generic and reusable concept is preferred. A deadlock prevention mechanism based on sequential numbering of the resources is adopted from computer science research. The entitlement to resources is an extension of this basic mechanism to increase the potential resource utilisation rate. More advanced resource allocation mechanisms can be introduced into the system by using the concept of aggregated processes (teams) and aggregated resources (domains). The presented deadlock avoidance concepts are being implemented in the prototype holonic manufacturing system currently under development.