Luc Bongaerts

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.

Hierarchy in distributed shop floor control

Abstract This discussion paper examines the role of hierarchy within the domain of shop floor control in manufacturing plants. Specifically, three distinct structures for shop floor control are considered, namely, hierarchical, heterarchical and holonic control systems. Holonic manufacturing is a novel paradigm for manufacturing that tries to merge the best properties of both hierarchical and heterarchical systems, namely, a high and predictable performance with a high robustness against disturbances. The paper identifies the concept of hierarchy in distributed shop floor control as one of the key contributions of holonic manufacturing. In a holonic architecture, the mapping of functions to control units remains flexible, such that decision power can be distributed over these units as needed. Based on the invariants concept of computer science, a modelling framework is proposed to identify the decision making needs of each unit. It can be used not only to describe the behaviour of the system, but also to impose performance and operational guarantees.

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.

Programming, scheduling, and control of flexible assembly systems

Abstract This paper surveys the research results on flexible assembly systems at the Mechanical Engineering Department of the Katholieke Universiteit Leuven. In the first section, it describes the overall architecture of the pilot assembly system. The second section surveys the programming methodology employed for the manufacturing equipment. The third section presents the control system and discusses its capabilities. The fourth section addresses the development and the integration of an on-line reactive scheduler. Finally, the last section discusses a benchmark that was performed in the framework of the fifth IMS test case.

IMS Test Case 5: Holonic Manufacturing Systems

Abstract This paper surveys the activities and results of the IMS test case entitled: ‘Holonic Manufacturing Systems.’ This one-year project covers a wide range of manufacturing systems, encompassing discrete, continuous and/or batch processing. It puts forward a new paradigm for manufacturing: the holonic manufacturing system. In addition, benchmark results are presented in this paper.

Architectural and System Design Issues in Holonic Manufacturing Systems

Abstract This paper describes research based on the HMS or Holonic Manufacturing Systems concept, which was elaborated in the IMS Test Case N° 5. First, the paper discusses the HMS paradigm. Second, it presents a number of fundamental properties of complex adaptive systems. Third, examples demonstrate how the insights of the previous section have an impact on the design and architecture of distributed manufacturing systems and their components.

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

Holonic manufacturing control systems : architecture and methodology

Abstract This paper presents ongoing research on Holonic Manufacturing Control at the PMA division of the K.U.Leuven. First, it introduces the concept of a Holonic System. Next, it describes the Holonic Manufacturing Control Architecture. Finally, the paper addresses the system development methodology