Adaptive Behavior, 5 (2)

We present a novel evolutionary approach to robotic control of a real robot based on genetic programming (GP). Our approach uses GP techniques that manipulate machine code to evolve control programs for robots. This variant of GP has several advantages over a conventional GP system, such as higher speed, lower memory requirements, and better real-time properties. Previous attempts to apply GP in robotics use simulations to evaluate control programs and have difficulties with learning tasks involving a real robot. We present an on-line control method that is evaluated in two different physical environments and applied to two tasks--obstacle avoidance and object following--using the Khepera robot platform. The results show fast learning and good generalization.

Key Words

real-time control; stimulus-response behavior; obstacle avoidance; genetic programming; online evolution; stochastic sampling

Pages 141-167

The Influence of Light-Dark Adaptation and Lateral Inhibition on Phototaxic Foraging: A Hypothetical Animal Study

By René J. V. Bertin and Wim A. van de Grind

Abstract

Vision did not arise and evolve merely so that individuals might "see" things but rather so that they might act on and interact with their habitat. Thus it might be misleading to study vision without looking also at its natural coupling to vital action. Here we investigate this problem in a simulation study of the simplest kind of visually guided foraging by a species of two-dimensional hypothetical animal called the (diurnal) paddler. In a previous study, we developed a hypothetical animal called the archaepaddler, which used positive phototaxis to forage for autoluminescent prey in a totally dark environment (the deep sea). Here we discuss possible visual mechanisms that allow (diurnal) paddlers to live in shallower water, foraging for light-reflecting prey in ambient light. The modification consists of two stages. In the first stage, Weber adaptation compresses the retinal illumination into an acceptable range of neural firing frequencies. In the second stage, high-pass filtering with lateral inhibition separates background responses from foreground responses. We report on a number of parameter studies conducted with the foraging diurnal paddler, in which the influence of dark-light adaptation and lateral inhibition on foreground-background segregation and foraging performance ("fitness") are quantified. It is shown that the paddler can survive adequately for a substantial range of parameters that compromises between discarding as much unwanted visual (background) information as possible and retaining as much information on potential prey as possible. Parameter values that optimize purely visual performance, such as foreground-background segregation, are not always optimal for foraging performance, and vice versa. This article shows that studies of vision might indeed require more serious consideration of the goals of vision and the ethogram of the studied organisms than has been customary.

Key Words

dark-light adaptation; lateral inhibition; hypothetical animal; phototaxic navigation; Weber adaptation

Pages 169-207

Ant-Based Load Balancing in Telecommunications Networks

By Ruud Schoonderwoerd, Owen E. Holland, Janet L. Bruten, and Leon J. M. Rothkrantz

Abstract

This article describes a novel method of achieving load balancing in telecommunications networks. A simulated network models a typical distribution of calls between nodes; nodes carrying an excess of traffic can become congested, causing calls to be lost. In addition to calls, the network also supports a population of simple mobile agents with behaviors modeled on the trail-laying abilities of ants. The ants move across the network between randomly chosen pairs of nodes; as they move, they deposit simulated pheromone as a function of their distance from their source node and the congestion encountered on their journey. They select their path at each intermediate node according to the distribution of simulated pheromone distributions at each intermediate node. The performance of the network is measured by the proportion of calls that are lost. The results of using ant-based control (ABC) are compared with those achieved by using fixed shortest-path routes, and also those achieved by using an alternative algorithmically based type of mobile agent previously proposed for use in network management. The ABC system is shown to result in fewer call failures than the other methods, while exhibiting many attractive features of distributed control.

Key Words

ants; telecommunications routing; stigmergy; emergent collective behavior; mobile agents; applications of adaptive behavior

Pages 209-213

Growing a Unified Social Science

By Bernhard Borges

Review of Growing Artificial Societies: Social Science from the Bottom Up, by Joshua M. Epstein and Robert Axtell. Cambridge, MA: MIT Press, 1996.

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Adaptive Behavior, 5 (2)

Adaptive Behavior

Volume 5, Number 2

Fall 1996

Table of Contents

Peter Nordin and Wolfgang Banzhaf

An On-Line Method to Evolve Behavior and to Control a Miniature Robot in Real Time with Genetic Programming