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Holonic-based Control System for Automated Material Handling Systems
Radu F. Babiceanu

Dissertation submitted to the Faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of

Doctor of Philosophy in Industrial and Systems Engineering

Dr. F. Frank Chen, Chair Dr. Robert H. Sturges, Jr. Dr. Subhash C. Sarin Dr. C.Patrick Koelling Dr. Philip Y. Huang

July 12, 2005 Blacksburg, Virginia
Keywords: Holonic manufacturing systems, Material handling systems, Real-time scheduling
Copyright © 2005 by Radu F. Babiceanu

Holonic-based Control System for Automated Material Handling Systems
Radu F. Babiceanu

ABSTRACT In real-word manufacturing environments, finding the right job sequences and their associatedschedules when resource, precedence, and timing constraints are imposed is a difficult task. For most practical problems classical scheduling easily leads to an exponential growth in the number of possible schedules. Moreover, a decision time period of hours or even minutes is too long. Good solutions are often needed in real-time. The problem becomes even more complicated if changes, such as neworders or resource breakdowns, occur within the manufacturing system. One approach to overcome the challenges of solving classical scheduling problems is the use of distributed schemes such as agent or holonic-based control architectures. This dissertation presents an innovative control architecture that uses the holonic concept, capable of delivering good solutions when applied in dynamicenvironments. The general holonic control framework presented in this research has specific characteristics not found in others reported so far. Using a modular approach it takes into account all the categories of hardware and software resources of a manufacturing system. Due to its modularity, the holonic control framework can be used for assigning and scheduling different task types, separately orsimultaneously. Thus, it can be used not only for assigning and scheduling transport tasks, but also for finding feasible solutions to the job assignment and scheduling of processing tasks, or to better utilize the auxiliary equipment and devices in a manufacturing system. In the holonic system, under real-time constraints, a feasible schedule for the material handling resources emerges from thecombination of individual holons’ schedules. Internal evaluation algorithms and coordination mechanisms between the entities in the architecture form the basis for the resultant schedules. The experimental results obtained show a percentage difference between the makespan values obtained using the holonic scheduling approach and the optimal values of under seven percent. Since current controlsystems in use in industry lack the ability to adapt to dynamic manufacturing environments, the holonic architecture designed and the tests performed in this research could be a part in the effort to build the foundations for the control systems of the next generation manufacturing systems.

Table of Contents
Nomenclature List of Tables List of Figures Acknowledgements Part I: General Information1. Introduction
1.1. Characteristics of the Global Manufacturing Environment 1.2. Automated Material Handling Systems xi xiv xviii xxii

1 2 2 2 4 4 5 6 6 10 11 11 12 13 14 16 16 17 19 19 20

2. Research Motivations, Objectives and Contributions
2.1. Previous Approaches to Manufacturing Systems Research and Implementation 2.2. Requirements for Next Generation Manufacturing Systems 2.3.Research Objectives 2.4. Contributions to the Manufacturing Systems Field

Part II: Background Information and Literature Review
3. Manufacturing Control Architectures
3.1. Centralized Control Architectures
3.1.1. Example of Centralized Control Architectures

3.2. Hierarchical Control Architectures
3.2.1. Examples of Hierarchical Control Architectures

3.3. Modified Hierarchical Control...
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