Holonic Manufacturing Systems: Phase II

Real time control of holonic manufacturing systems requires a radically different approach from that of traditional unit level regulatory control. Because they need to automatically adapt and reconfigure based on the ever changing requirements of the manufacturing system, control systems based on this approach are termed metamorphic control systems. The engineering of such software centric metamorphic control systems for dynamically reconfigurable distributed multi sensor based holonic systems is addressed. An integrated and uniform event driven control architecture is specified for various functional levels of metamorphic control system. This architecture utilizes the emerging International Electrotechnical Commission function block standard (IEC 1499) for industrial process measurement and control systems to specify the requisite behavior of distributed control software components (agents).

The field of holonic manufacturing was initiated in the early 1990s to address the upcoming challenges for manufacturing operations in the 21st century. It is intended to support highly responsive organizations by providing a modular building block or 'plug and play' capability for developing and operating a manufacturing production system. The holonic approach can be viewed as an alternative to more hierarchical operations management methods such as those based on computer- integrated manufacturing (CIM). Since 1990, an increasing amount of research has been conducted in holonic manufacturing over a diverse range of industries and applications, with a strong emphasis on how holonic systems will perform the different planning and control functions required to manage a production operation. The planning and control work to date has, however, been focussed on specific problem formulations and solution strategies. The intention of this paper is to provide an overview of the use of holonic manufacturing concepts in production planning and control which is accessible to both practitioners and researchers in the area. The aims of the paper are as follows. To define clearly what is meant by a holonic manufacturing system and to demonstrate the relevance of its development to production planning and control. To motivate holonic manufacturing based on a business rationale, demonstrating specifically how it can support improved responsiveness and the management of production complexity. To review existing work in holonic manufacturing systems relevant to production planning and control, and provide an analysis of the scope and applicability of these results.

The holonic manufacturing system paradigm is a derivation of a classical framework theory, and has implications at all levels of a manufacturing system. In this paper, the authors present the main concepts of holonic systems and some issues related to the collaboration and coordination aspects in this context. Finally, some considerations of implementation are made.

An architecture for metamorphic control of holonic manufacturing systems

The design and development of holonic manufacturing systems requires careful, and sometimes risky, decision making to ensure that they will successfully satisfy the demands of an ever-changing market. In this paper, the authors propose a methodology for a holonic manufacturing systems requirement analysis that is based on a virtual reality approach and aimed at assisting designers of such systems along the entire systems design and development process. Exploiting virtual reality helps the user collect valid information quickly and in a correct form by putting the user and the information support elements in direct relation with the operation of the system in a more realistic environment. A prototype software system tool is designed to realise the features outlined in each phase of the methodology. A virtual manufacturing environment for matching the physical and the information model domains is utilised to delineate the information system requirements of holonic manufacturing systems implementation. A set of rules and a knowledge base is appended to the virtual environment to remove any inconsistency that could arise between the material and the information flows during the requirement analysis.

In a Holonic system the issues concerned with interfacing to the physical equipment are of utmost importance. The two performance criteria for agile systems defined as structural and operational performance have to be optimised. This necessitates a clear model of the capabilities of the physical equipment encapsulated within the Holon. This is achieved through a generic model representing the states and capabilities of the physical equipments, which the Holon uses for structural and operational changes. This model is implemented in the HoMuCS architecture, which is a specific implementation of the Holonic Manufacturing System theory, with the VMD class. The paper briefly describes the Holonic Manufacturing Systems (HMS) and the HoMuCS architecture. It then supplements with a more in depth description of the characteristics and architecture of this VMD and its capability model. The use of a VMD class is exemplified through a case study.

The objective of the research described is to develop an integrated process planning and scheduling system of machine products, aiming at realizing flexible production control in holonic manufacturing systems. The basic architecture of the holonic manufacturing system is discussed from the viewpoint of the integration of the process planning and the scheduling systems. Procedures are proposed to select suitable machining sequences of machining features and suitable sequences of machining equipment, taking into consideration future schedules of machining equipment. A combined method of genetic algorithm and dynamic programming is applied to selection of the machining sequence and the sequence of the machining equipment.

Engineering Holonic Manufacturing Systems

The paper examines some issues relating to an open architecture for holon cooperation and autonomy. We identify the requirements of a holonic system architecture and discuss the merits of our approach in comparison with classic agent-based models. A suitable architecture to satisfy these requirements is also presented, together with a discussion of the holonic kernel needed to support distributed holonic control. The material presented is based on results from the international programme on Holonic Manufacturing Systems (HMS).

This paper documents the fact that the research in the two areas of holonic manufacturing systems and multi-agent systems contains substantial overlap. Many technologies and results achieved in the multi-agent area can be applied with advantage in the holonic field. This is especially true when talking about standardisation, which should enable interoperability of systems. The FIPA international consortium has introduced a systematic approach to development and maintenance of specifications and standards for the multi-agent domain. The principles of the FIPA Abstract Architecture are briefly described. Two examples of applications of FIPA standards in different areas within the scope of holonic systems (control, and production planning and supply chain management) are presented. FIPA standards have been recognised as a suitable candidate for ensuring complete interoperability in the holonic field.

Metrics for evaluating distributed manufacturing control systems

Assistance tools for actors of cooperative systems, which are often centralized are increasingly designed to adhere to the system organization using a distributed architecture. However, generally these systems have difficulty in managing data coherency at the global level. In answer to this problem, we turned towards a particular organizational model: holonic systems. This concept has guided us in the design of the Holonic Multi-Agent System (HOLOMAS), which offers a good compromise between the distribution of knowledge and control centralization. In fact, the use of the HOLOMAS appeared to be necessary following the study of the procedures used in the patent department of a large company.

This paper presents an innovative Multi-Agent approach related to an advanced real time control of flexible manufacturing systems. The proposed architecture is based on the paradigm of Distributed Intelligence and Multi-Agent Systems. The developed Multi-Agent prototype system integrates the following functions: Scheduling, dispatching, monitoring and error handling. A new negotiation protocol for manufacturing systems is presented in this paper. The purpose of this protocol is to assign dynamic operations to the resources of the Manufacturing System in order to accomplish the proposed tasks. This protocol is able to deal with exceptions.

In this paper, we propose a procedure for production flow control in reentrant manufacturing systems. The system under study consists ofN machines and producesM product types simultaneously. Each part goes through the system following a predefined process and may visit a machine many times. All machines are subject to random failures and need random repair times. The scheduling objectives are to keep the production close to demand and to keep the WIP inventory level and cycle times at low values. The model is motivated by semiconductor fabrication production. A three-level hierarchical controller is constructed to regulate the production. At the top level of this hierarchy, we perform capacity planning by selecting the desirable buffer sizes and the target production level for each operation. A production flow rate controller is at the middle level which recalculates the production rates whenever a machine fails or is starved or blocked. The loading times for individual parts are determined at the bottom level of the hierarchy. Comparison with alternative control is made through simulation and it shows that the control policy performs well.

This paper deals with a real time scheduling system of a holonic manufacturing system for machining process. The holonic manufacturing system was proposed aiming at realizing more flexible and robust control structures of the manufacturing systems which can cope with the variety of the products and the unscheduled disruptions, such as status changes of equipment and input of high priority jobs. Decision making procedures of individual holons are discussed in the paper to establish a real-time scheduling method, and an emulation system for evaluation of real-time scheduling process.