Control of Walking in the Stick Insect: From Behavior and Physiology to Modeling

  • Authors:
  • Jeffrey Dean;Thomas Kindermann;Josef Schmitz;Michael Schumm;Holk Cruse

  • Affiliations:
  • Abteilung für Biokybernetik und theoretische Biologie, Universität Bielefeld, Postfach 100 131, D-33501 Bielefeld, FRG. j.dean@csuohio.edu;Abteilung für Biokybernetik und theoretische Biologie, Universität Bielefeld, Postfach 100 131, D-33501 Bielefeld, FRG;Abteilung für Biokybernetik und theoretische Biologie, Universität Bielefeld, Postfach 100 131, D-33501 Bielefeld, FRG;Abteilung für Biokybernetik und theoretische Biologie, Universität Bielefeld, Postfach 100 131, D-33501 Bielefeld, FRG;Abteilung für Biokybernetik und theoretische Biologie, Universität Bielefeld, Postfach 100 131, D-33501 Bielefeld, FRG

  • Venue:
  • Autonomous Robots
  • Year:
  • 1999

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Abstract

Classical engineering approaches to controlling a hexapodwalker typically involve a central control instance that implementsan abstract optimal gait pattern and relies on additionaloptimization criteria to generate reference signals forservocontrollers at all the joints. In contrast, the gait of theslow-walking stick insect apparently emerges from an extremelydecentralized architecture with separate step pattern generators foreach leg, a strong dependence on sensory feedback, and multiple, inpart redundant, primarily local interactions among the step patterngenerators. Thus, stepping and step coordination do not reflect anexplicit specification based on a global optimization using arepresentation of the system and its environment; instead they emergefrom a distributed system and from the complex interaction with theenvironment. A similarly decentralized control at the level of singleleg joints also may explain the control of leg dynamics. Simulationsshow that negative feedback for control of body height and walkingdirection combined with positive feedback for generation ofpropulsion produce a simple, extremely decentralized system that canhandle a wide variety of changes in the walking system and itsenvironment. Thus, there is no need for a central controllerimplementing global optimization. Furthermore, physiological resultsindicate that the nervous system uses approximate algorithms toachieve the desired behavioral output rather than an explicit, exactsolution of the problem. Simulations and implementation of thesedesign principles are being used to test their utility forcontrolling six-legged walking machines.