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Proceedings Paper

Analysis of decentralized variable structure control for collective search by mobile robots
Author(s): Steven Y. Goldsmith; John T. Feddema; Rush D. Robinett
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Paper Abstract

This paper presents an analysis of a decentralized coordination strategy for organizing and controlling a team of mobile robots performing collective search. The alpha- beta coordination strategy is a family of collective search algorithms that allow teams of communicating robots to implicitly coordinate their search activities through a division of labor based on self-selected roles. In an alpha- beta team, alpha agents are motivated to improve their status by exploring new regions of the search space. Beta agents are conservative, and rely on the alpha agents to provide advanced information on favorable regions of the search space. An agent selects its current role dynamically based on its current status value relative to the current status values of the other team members. Status is determined by some function of the agent's sensor readings, and is generally a measurement of source intensity at the agent's current location. Variations on the decision rules determining alpha and beta behavior produce different versions of the algorithm that lead to different global properties. The alpha-beta strategy is based on a simple finite-state machine that implements a form of Variable Structure Control (VSC). The VSC system changes the dynamics of the collective system by abruptly switching at defined states to alternative control laws. In VSC, Lyapunov's direct method is often used to design control surfaces which guide the system to a given goal. We introduce the alpha- beta algorithm and present an analysis of the equilibrium point and the global stability of the alpha-beta algorithm based on Lyapunov's method.

Paper Details

Date Published: 9 October 1998
PDF: 8 pages
Proc. SPIE 3523, Sensor Fusion and Decentralized Control in Robotic Systems, (9 October 1998); doi: 10.1117/12.327013
Show Author Affiliations
Steven Y. Goldsmith, Sandia National Labs. (United States)
John T. Feddema, Sandia National Labs. (United States)
Rush D. Robinett, Sandia National Labs. (United States)


Published in SPIE Proceedings Vol. 3523:
Sensor Fusion and Decentralized Control in Robotic Systems
Paul S. Schenker; Gerard T. McKee, Editor(s)

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