Seen with the eyes of a traditional ethologist, walking appears to be a basic and therefore not very interesting behaviour. Although at first sight control of walking seems to be a simple task, the underlying problems become however apparent as soon as an artificial walking system is to be constructed. Control of walking has to deal with all fundamental problems that appear when it comes to the control of behaviour in general. Control of walking has to be extremely adaptive to immediate changes in the environment and therefore heavily relies on sensory input. Sensory input depends not only on the properties of the environment, but also on the own motor actions. Looking at this task with the eyes of an engineer, fast, robust and reliable control of locomotion immediately reveals its complexity. More than 10 years ago (1990 and 1991), two small workshops held at the ZiF stimulated the cooperation of several groups, biologists and engineers, to concentrate on the construction of walking machines. Since 1997 a DFG priority program (Autonomous Walking) has been installed, the results of which have now been presented at the ZiF:Workshop Walking Machines. A number of different solutions have been shown dealing with different problems that can be naturally ordered into problems that occur with a varying number of legs: there are two-legged systems, four-legged systems and systems with six (and more) legs. Increasing the number of legs decreases the difficulty of maintaining a stabile body posture, but increases the problem of coordination of the high number of available degrees of freedom. Six robots with impressive properties have been presented that show different ways of approaching the problems: The two-legged humanoid robot Johnnie from the Technical University of Munich, one four-legged and two six-legged systems from the University of Karlsruhe, the stick insect-like robot Tarry developed together at the Universities of Duisburg and Bielefeld, and the eight-legged robot Scorpion from the University of Bremen. In addition, progress was reported in the field of biology. This includes behavioural studies of walking on difficult terrain as well as studies concerning the underlying neuronal structure. The latter results together with several simulation studies pointed to open questions that require further research in engineering sciences. On the lower level these questions concern the contribution of mechanical system, in particular the properties of muscle-like systems compared to electric motors that could dramatically simplify the control of legged movement. On the higher level, cognitive properties have to be studied that allow for the control of bodies with high degrees of redundancy and, probably a related problem, for the capability to plan ahead.
Marko Ackermann (Stuttgart), Jan Albiez (Karlsruhe), Wolfgang Banzhaf (Dortmund), Karsten Berns (Kaiserslautern), Bettina Bläsing (Bielefeld), Reinhard Blickhan (Jena), Till Bockemühl (Bielefeld), Anke Borgmann (Köln), Thomas Buschmann (Garching), Ansgar Büschges (Köln), Holk Cruse (Bielefeld), Joachim Denk (München), Rüdiger Dillmann (Karlsruhe), Elmar Dittrich (Ilmenau), Volker Dürr (Bielefeld), Wiebke Ebeling (Bielefeld), Örjan Ekeberg (Stockholm), Martin S. Fischer (Jena), Leonid Frantsevich (Bielefeld), Jens Peter Gabriel (Köln), Bernd Gassmann (Karlsruhe), Daniel Germann (Duisburg), Sibylle Grunze (Ludwigsburg), Michael Günther (Tübingen), Rémi Hackert (Jena), Bodo Heimann (Hannover), Hugh Herr (Cambridge, MA), Manfred Hiller (Duisburg), R. M. Hochkönig (Ludwigsburg), Jürgen Hoefeld (Bonn), Kerstin Hoppenhaus (Ludwigsburg), Omar Jimenez (Ilmenau), Rainer Keppler (Karlsruhe), Jutta Kiener (Darmstadt), Hiroshi Kimura (Tokio), Frank Kirchner (Bremen), Daniel E. Koditschek (Ann Arbor, MI), André Krause (Bielefeld), Antje Krutz (Ludwigsburg), Simone Kühn (Bielefeld), Oliver Lenord (Duisburg), Manuela Lenzen (Bielefeld), Annette Leßmöllmann (Hamburg), Christian Lindner (Bielefeld), Klaus Löffler (Garching), Sebastian Lohmeier (Garching), Georg Mayr (Garching), Ralf Möller (München), Günther Palm (Ulm), Seunjae Park (Bielefeld), Friedrich Pfeiffer (Garching), Eugen Pflüger (Ludwigsburg), Simon Pick (Würzburg), Tamina Pinent (Bielefeld), Arthur Prochazka (Edmonton), Lars Quernheim (Hannover), Christian T. Remiger (Ludwigsburg), Thorsten Roggendorf (Bielefeld), Werner Schiehlen (Stuttgart), Günther Schmidt (München), Syn Schmitt (Tübingen), Josef Schmitz (Bielefeld), Axel Schneider (Bielefeld), Javier Fernández Seara (München), Werner von Seelen (Bochum), Katja Sievers (Bielefeld), Dirk Spenneberg (Bremen), Maximilian Stelzer (Darmstadt), Günther Stelzner (Karlsruhe), Viola Stephan (Berlin), Oskar von Stryk (Darmstadt), Thomas Thümmel (Garching), Henning Tolle (Darmstadt), Veit Wank (Karlsruhe), Inga Werner (Bielefeld), Hartmut Witte (Ilmenau), Jens Wittenburg (Karlsruhe), Harald Wolf (Ulm), Dirk Wollherr (Berlin), Sergiy Yakovenko (Edmonton), Jure Zadotnik (Bielefeld), J. Marius Zöllner (Karlsruhe)