SELF-ORGANIZATION IN LARGE
POPULATIONS OF MOBILE ROBOTS

Abstract

A homogeneous population of robots described as an Army-ant swarm is to be realized for material transportation. Robots envisioned in the Army-ant scenario are relatively small, independent autonomous mobile robots which can cooperatively carry palletized loads. In this thesis, the agents are treated as a self-organizing system of moving points. This characteristic makes the Army-ant swarm a modular, adaptive and dynamic system.

Several algorithms for spatial self-organization of the robots are given. Self-organizing agents can arrange themselves geometrically in two- and three-dimensional space using only local information about teammates. The method is a distributed one: each agent uses only the information obtained by its own sensors. Algorithms are based on feasible assumptions. It is also shown possible to divide such a population into different groups around goals by communicating minimal data. Data transfer has a broadcast characteristic.

Behavioral self-organization in the Army-ant scenario is also investigated. Activation and inhibition relations between robots determine the behavior (position in a behavioral space) of the agents, while in spatial self-organization force fields are in effect.

Several problems which may be encountered and the solution to some of these problems are outlined. Methods for communication and cooperative decision systems -such as coupled van der Pol oscillators- in finding and carrying the pallets are proposed. Sensors and communication systems which may be used in the Army-ant scenario are also briefly discussed.

Dedication

Acknowledgments

Han Kiliççöte and Ergin Güney, two exceptional friends, were so gracious in providing me some of the tools I needed for research and documentation. Aylin Barlas, a fellow graduate student who certainly understood what I have been through, was always available for an irrelevant question (or for a visit to Capri Twin). Also Elif Evin, ex-manita extraordinaire, was always with me no matter how dubious my decisions were. And I believe I owe many thanks to my parents Ayhan & Aydin Ünsal who were very supportive of my academic venture.

1. Introduction
   • 1.1 Motivation
   • 1.2 Context
   • 1.3 Scope and Structure of Thesis

2. Review of Literature
   • 2.1 Self-Organization
   • 2.2 Natural Systems
   • 2.3 Multiple Mobile Robots
   • 2.4 Learning and Decision-Making

3. Spatial Self-Organization
   • 3.1 Formation of a Circle Around a Goal
   • 3.2 Alterations and interpretations of the algorithm
   • 3.3 Formation of a Paraboloid
   • 3.4 Multigoal situations
   • 3.5 Other issues

4. Behavioral Self-Organization
   • 4.1 Behavioral Model of Army-ant Robots
   • 4.2 System-level analysis of Army-ant problem
   • 4.3 Team Coordination

5. Technical Assessment
   • 5.1 A Communication Method: Binary Coded Signals
   • 5.2 Sensors

6. Conclusions and Future Research
   • 6.1 Conclusions
   • 6.2 Areas of Further Development

7. Appendix
   • Programs
   • Matlab/Simulink Simulation Snapshots

8. Bibliography

9. Vita

Library Information

from vtls.vt.edu (128.173.16.7)

 CALL NUMBER: LD5655 V855 1993 U572                                            
      Author: Unsal, Cem, 1967-                                                
       Title: Self-organization in large populations of mobile robots
	      / by Cem Unsal.                                                 
     Imprint: 1993.                                                            
 Description: xi, 128 leaves : ill. ; 28 cm.                                   
      Series: VPI & SU. Electrical Engineering. M.S. 1993.                     
        Note: Vita.                                                            
        Note: Abstract.                                                        
        Note: Thesis (M.S.)--Virginia Polytechnic Institute and State          
              University, 1993.                                           
        Note: Bibliography: leaves 124-127.