(cid:2)(cid:3)(cid:4)(cid:5)(cid:4)(cid:6)(cid:3)(cid:7)(cid:8)(cid:5)(cid:5)(cid:9) (cid:10)(cid:11)(cid:12)(cid:13)(cid:3)(cid:14)(cid:15)(cid:16) (cid:17)(cid:4)(cid:18)(cid:4)(cid:19) (cid:2)(cid:15)(cid:20)(cid:8)(cid:21)(cid:3)(cid:4)(cid:14) (cid:22)(cid:11)(cid:6)(cid:3)(cid:11)(cid:15)(cid:15)(cid:14)(cid:3)(cid:11)(cid:6) (cid:23)(cid:19)(cid:24)(cid:16)(cid:3)(cid:15)(cid:12) (cid:3)(cid:11) (cid:25)(cid:24)(cid:26)(cid:26)(cid:3)(cid:11)(cid:15)(cid:12)(cid:12) (cid:8)(cid:11)(cid:16) (cid:23)(cid:4)(cid:27)(cid:19) (cid:28)(cid:4)(cid:29)(cid:13)(cid:24)(cid:19)(cid:3)(cid:11)(cid:6) (cid:2)(cid:3)(cid:4)(cid:5)(cid:6)(cid:7)(cid:8)(cid:4)(cid:9)(cid:8)(cid:10)(cid:11)(cid:4)(cid:12)(cid:13) (cid:30)(cid:14)(cid:4)(cid:27)(cid:31) (cid:8)(cid:11)(cid:24)(cid:12)(cid:26) !(cid:8)(cid:7)(cid:13)(cid:14)(cid:26)(cid:9)" (cid:23)(cid:9)(cid:12)(cid:19)(cid:15)(cid:29)(cid:12) (cid:17)(cid:15)(cid:12)(cid:15)(cid:8)(cid:14)(cid:7)(cid:20) (cid:10)(cid:11)(cid:12)(cid:19)(cid:3)(cid:19)(cid:24)(cid:19)(cid:15) (cid:30)(cid:4)(cid:5)(cid:3)(cid:12)(cid:20) #(cid:7)(cid:8)(cid:16)(cid:15)(cid:29)(cid:9) (cid:4)(cid:27) (cid:23)(cid:7)(cid:3)(cid:15)(cid:11)(cid:7)(cid:15)(cid:12) (cid:24)(cid:5)(cid:31) $(cid:15)%(cid:15)(cid:5)(cid:12)"(cid:8) & ’()**+ ,(cid:8)(cid:14)(cid:12)(cid:8)%- (cid:30)(cid:4)(cid:5)(cid:8)(cid:11)(cid:16) (cid:22))(cid:29)(cid:8)(cid:3)(cid:5). "(cid:8)(cid:7)(cid:13)(cid:14)(cid:26)(cid:9)"/(cid:3)(cid:18)(cid:12)(cid:13)(cid:8)(cid:11)(cid:31)%(cid:8)%(cid:31)(cid:13)(cid:5) (cid:20)(cid:19)(cid:19)(cid:13).00%%%(cid:31)(cid:12)(cid:13)(cid:14)(cid:3)(cid:11)(cid:6)(cid:15)(cid:14)(cid:31)(cid:16)(cid:15)0(cid:7)(cid:6)(cid:3))(cid:18)(cid:3)(cid:11)0(cid:12)(cid:15)(cid:8)(cid:14)(cid:7)(cid:20)1(cid:18)(cid:4)(cid:4)"(cid:31)(cid:13)(cid:5)2(cid:12)(cid:15)(cid:14)(cid:3)(cid:15)(cid:12)345*( (cid:25)(cid:24)(cid:14)(cid:19)(cid:20)(cid:15)(cid:14) (cid:21)(cid:4)(cid:5)(cid:24)(cid:29)(cid:15)(cid:12) (cid:4)(cid:27) (cid:19)(cid:20)(cid:3)(cid:12) (cid:12)(cid:15)(cid:14)(cid:3)(cid:15)(cid:12) (cid:7)(cid:8)(cid:11) 6(cid:4)(cid:5)(cid:31)57(cid:31)<(cid:31)(cid:28)(cid:31) (cid:8)(cid:3)(cid:11)-D(cid:31)(cid:28)(cid:20)(cid:15)(cid:11)(cid:8)(cid:11)(cid:16)$(cid:31)(cid:10)(cid:7)(cid:20)(cid:8)(cid:5)"(cid:8)(cid:14)(cid:8)(cid:11)F(cid:15) (cid:18)(cid:15) (cid:27)(cid:4)(cid:24)(cid:11)(cid:16) (cid:8)(cid:19) (cid:4)(cid:24)(cid:14) (cid:20)(cid:4)(cid:29)(cid:15)(cid:13)(cid:8)(cid:6)(cid:15)(cid:31) >(cid:22)(cid:16)(cid:12)(cid:31)? (cid:17)(cid:6)(cid:15)(cid:3)(cid:8)(cid:8)(cid:10)(cid:9)(cid:3)(cid:6)(cid:15))(cid:9)(cid:3)(cid:6)(cid:15)(cid:11)(cid:28)(cid:6)(cid:30)(cid:2)(cid:5)(cid:3)(cid:10)(cid:13))##(cid:8)(cid:10)(cid:4)(cid:28)(cid:15)(cid:10)(cid:7)(cid:6)(cid:11)(cid:22)(cid:23)(cid:24)(cid:24)(cid:23) (cid:10)(cid:23)(cid:2)$@)+5’7)(*&5)A 6(cid:4)(cid:5)(cid:31)75(cid:31)(cid:2)(cid:31)(cid:2)(cid:4)(cid:24)(cid:7)(cid:20)(cid:4)(cid:11))8(cid:15)(cid:24)(cid:11)(cid:3)(cid:15)(cid:14)- (cid:31)9(cid:24)(cid:19)(cid:3):(cid:14)(cid:14)(cid:15)(cid:26))(cid:17);(cid:4)(cid:12)- <(cid:31)8(cid:8)(cid:6)(cid:16)(cid:8)(cid:5)(cid:15)(cid:11)(cid:8)(cid:8)(cid:11)(cid:16)(cid:17)(cid:31)(cid:17)(cid:31)=(cid:8)(cid:6)(cid:15)(cid:14)>(cid:22)(cid:16)(cid:12)(cid:31)? 6(cid:4)(cid:5)(cid:31)55(cid:31)(cid:28)(cid:31)E(cid:24)(cid:8)(cid:11)(cid:6)(cid:8)(cid:11)(cid:16)=(cid:31)(cid:23)(cid:20)(cid:3) (cid:2)(cid:3)(cid:4)(cid:5)(cid:6)(cid:7)(cid:8)(cid:7)(cid:9)(cid:10)(cid:3)(cid:11)(cid:12)(cid:7)(cid:13)(cid:14)(cid:7)(cid:6)(cid:11)(cid:15)(cid:13)(cid:16)(cid:4)(cid:15)(cid:10)(cid:6)(cid:9)(cid:17)(cid:6)(cid:15)(cid:3)(cid:8)(cid:8)(cid:10)(cid:9)(cid:3)(cid:6)(cid:15)(cid:18)(cid:19)(cid:11)(cid:15)(cid:3)(cid:20)(cid:11)(cid:21)(cid:22) (cid:2)(cid:7)+(cid:28)(cid:13)(cid:30)(cid:11)(cid:29)(cid:12)(cid:12)(cid:10)(cid:4)(cid:10)(cid:3)(cid:6)(cid:15)(cid:25)(cid:16)(cid:26)(cid:26)(cid:19)(cid:17)(cid:6)(cid:12)(cid:7)(cid:13)(cid:20)(cid:28)(cid:15)(cid:10)(cid:7)(cid:6)’(cid:13)(cid:7)(cid:4)(cid:3)(cid:11)(cid:11)(cid:10)(cid:6)(cid:9)(cid:22) (cid:23)(cid:24)(cid:24)(cid:23) (cid:23)(cid:24)(cid:24)(cid:23) (cid:10)(cid:23)(cid:2)$@)+5’7)(*A*)+ (cid:10)(cid:23)(cid:2)$@)+5’7)(*+A)C 6(cid:4)(cid:5)(cid:31)5’(cid:31)(cid:2)(cid:31)(cid:2)(cid:4)(cid:24)(cid:7)(cid:20)(cid:4)(cid:11))8(cid:15)(cid:24)(cid:11)(cid:3)(cid:15)(cid:14)- (cid:31)9(cid:24)(cid:19)(cid:3):(cid:14)(cid:14)(cid:15)(cid:26))(cid:17);(cid:4)(cid:12)- 6(cid:4)(cid:5)(cid:31)(’’(cid:31)(cid:23)(cid:31))E(cid:31)(cid:28)(cid:20)(cid:15)(cid:11)>(cid:22)(cid:16)(cid:31)? <(cid:31)8(cid:8)(cid:6)(cid:16)(cid:8)(cid:5)(cid:15)(cid:11)(cid:8)(cid:8)(cid:11)(cid:16)(cid:17)(cid:31)(cid:17)(cid:31)=(cid:8)(cid:6)(cid:15)(cid:14)>(cid:22)(cid:16)(cid:12)(cid:31)? (cid:29)(cid:31)(cid:7)(cid:8)(cid:16)(cid:15)(cid:10)(cid:7)(cid:6)(cid:28)(cid:13)(cid:19)(cid:14)(cid:7)(cid:20)#(cid:16)(cid:15)(cid:28)(cid:15)(cid:10)(cid:7)(cid:6) (cid:2)(cid:3)(cid:4)(cid:5)(cid:6)(cid:7)(cid:8)(cid:7)(cid:9)(cid:10)(cid:3)(cid:11)(cid:12)(cid:7)(cid:13)(cid:14)(cid:7)(cid:6)(cid:11)(cid:15)(cid:13)(cid:16)(cid:4)(cid:15)(cid:10)(cid:6)(cid:9)(cid:17)(cid:6)(cid:15)(cid:3)(cid:8)(cid:8)(cid:10)(cid:9)(cid:3)(cid:6)(cid:15)(cid:18)(cid:19)(cid:11)(cid:15)(cid:3)(cid:20)(cid:11)(cid:23)(cid:22) (cid:10)(cid:6)(cid:29)(cid:4)(cid:7)(cid:6)(cid:7)(cid:20)(cid:10)(cid:4)(cid:11)(cid:28)(cid:6)(cid:30)(cid:25)(cid:10)(cid:6)(cid:28)(cid:6)(cid:4)(cid:3)(cid:22)(cid:23)(cid:24)(cid:24)(cid:23) (cid:23)(cid:24)(cid:24)(cid:23) (cid:10)(cid:23)(cid:2)$@)+5’7)(*+&)7 (cid:10)(cid:23)(cid:2)$@)+5’7)(*AA)A 6(cid:4)(cid:5)(cid:31)(’((cid:31)(cid:23)(cid:31) (cid:31)G(cid:21)(cid:8)(cid:12)"(cid:8)(cid:8)(cid:11)(cid:16)<(cid:31)8(cid:31)(cid:23)(cid:26)(cid:19)(cid:8)(cid:11)(cid:16)(cid:15)(cid:14)(cid:8)>(cid:22)(cid:16)(cid:12)(cid:31)? (cid:18)(cid:7)(cid:12)(cid:15)(cid:14)(cid:7)(cid:20)#(cid:16)(cid:15)(cid:10)(cid:6)(cid:9)(cid:10)(cid:6)(cid:17)(cid:6)(cid:30)(cid:16)(cid:11)(cid:15)(cid:13)(cid:10)(cid:28)(cid:8)(cid:29)(cid:8)(cid:3)(cid:4)(cid:15)(cid:13)(cid:7)(cid:6)(cid:10)(cid:4)(cid:11)(cid:22)(cid:23)(cid:24)(cid:24)(cid:23) 6(cid:4)(cid:5)(cid:31)5((cid:31) (cid:31) (cid:31)(cid:2)(cid:24)(cid:7)"(cid:5)(cid:15)(cid:9)-(cid:22)(cid:31)(cid:22)(cid:12)(cid:5)(cid:8)(cid:29)(cid:3)(cid:8)(cid:11)(cid:16)B(cid:31)(cid:25)(cid:15)(cid:24)(cid:14)(cid:3)(cid:11)(cid:6) (cid:10)(cid:23)(cid:2)$@)+5’7)(*++)& (cid:25)(cid:16)(cid:26)(cid:26)(cid:19)(cid:27)(cid:28)(cid:15)(cid:5)(cid:3)(cid:20)(cid:28)(cid:15)(cid:10)(cid:4)(cid:11)(cid:10)(cid:6)(cid:29)(cid:4)(cid:7)(cid:6)(cid:7)(cid:20)(cid:10)(cid:4)(cid:11)(cid:28)(cid:6)(cid:30)(cid:29)(cid:6)(cid:9)(cid:10)(cid:6)(cid:3)(cid:3)(cid:13)(cid:10)(cid:6)(cid:9)(cid:22) (cid:23)(cid:24)(cid:24)(cid:23) 6(cid:4)(cid:5)(cid:31)(’4(cid:31)(cid:2)(cid:31)<(cid:3)(cid:24) (cid:10)(cid:23)(cid:2)$@)+5’7)(*A&)@ (cid:2)(cid:5)(cid:3)(cid:7)(cid:13)(cid:19)(cid:28)(cid:6)(cid:30)’(cid:13)(cid:28)(cid:4)(cid:15)(cid:10)(cid:4)(cid:3)(cid:7)(cid:12),(cid:6)(cid:4)(cid:3)(cid:13)(cid:15)(cid:28)(cid:10)(cid:6)’(cid:13)(cid:7)(cid:9)(cid:13)(cid:28)(cid:20)(cid:20)(cid:10)(cid:6)(cid:9)(cid:22) (cid:23)(cid:24)(cid:24)(cid:23) 6(cid:4)(cid:5)(cid:31)54(cid:31)(cid:30)(cid:31)(cid:30)(cid:31)#(cid:11)(cid:6)(cid:15)(cid:5)(cid:4)(cid:21) (cid:10)(cid:23)(cid:2)$@)+5’7)(*5’)@ (cid:29)(cid:31)(cid:7)(cid:8)(cid:31)(cid:10)(cid:6)(cid:9) (cid:16)(cid:8)(cid:3)!"(cid:28)(cid:11)(cid:3)(cid:30)(cid:27)(cid:7)(cid:30)(cid:3)(cid:8)(cid:11)(cid:22)(cid:23)(cid:24)(cid:24)(cid:23) (cid:10)(cid:23)(cid:2)$@)+5’7)(*A+)( 6(cid:4)(cid:5)(cid:31)(’@(cid:31)$(cid:31)(cid:2)(cid:8)(cid:14)(cid:11)(cid:15)(cid:12)(cid:8)(cid:11)(cid:16)D(cid:31))H(cid:31)<(cid:3)(cid:24) -(cid:6)(cid:7)+(cid:8)(cid:3)(cid:30)(cid:9)(cid:3)!"(cid:28)(cid:11)(cid:3)(cid:30).(cid:10)(cid:11)(cid:10)(cid:7)(cid:6)!((cid:16)(cid:10)(cid:30)(cid:3)(cid:30) (cid:7)$(cid:7)(cid:15)(cid:11)(cid:22)(cid:23)(cid:24)(cid:24)(cid:23) 6(cid:4)(cid:5)(cid:31)5@(cid:31)6(cid:31)6(cid:31)(cid:28)(cid:14)(cid:4)(cid:12)(cid:12)(cid:8)(cid:11)(cid:16)B(cid:31)#(cid:31)(cid:23)(cid:24)(cid:16)"(cid:8)(cid:29)(cid:13) (cid:10)(cid:23)(cid:2)$@)+5’7)(*5*)& (cid:18)(cid:10)(cid:20)(cid:10)(cid:8)(cid:28)(cid:13)(cid:10)(cid:15)(cid:19)(cid:28)(cid:6)(cid:30)(cid:14)(cid:7)(cid:20)#(cid:28)(cid:15)(cid:10)$(cid:10)(cid:8)(cid:10)(cid:15)(cid:19)(cid:10)(cid:6)(cid:25)(cid:16)(cid:26)(cid:26)(cid:19)(cid:18)(cid:3)(cid:15)(cid:2)(cid:5)(cid:3)(cid:7)(cid:13)(cid:19)(cid:22) (cid:23)(cid:24)(cid:24)(cid:23) 6(cid:4)(cid:5)(cid:31)(’*(cid:31)(cid:25)(cid:31)(cid:17)(cid:4)(cid:19)(cid:20)(cid:5)(cid:8)(cid:24)(cid:27) (cid:10)(cid:23)(cid:2)$@)+5’7)(*A7)C (cid:3)#(cid:13)(cid:3)(cid:11)(cid:3)(cid:6)(cid:15)(cid:28)(cid:15)(cid:10)(cid:7)(cid:6)(cid:11)(cid:12)(cid:7)(cid:13)((cid:3)(cid:6)(cid:3)(cid:15)(cid:10)(cid:4)(cid:28)(cid:6)(cid:30)(cid:29)(cid:31)(cid:7)(cid:8)(cid:16)(cid:15)(cid:10)(cid:7)(cid:6)(cid:28)(cid:13)(cid:19) )(cid:8)(cid:9)(cid:7)(cid:13)(cid:10)(cid:15)(cid:5)(cid:20)(cid:11)(cid:22)(cid:23)(cid:24)(cid:24)(cid:23) 6(cid:4)(cid:5)(cid:31)5*(cid:31)8(cid:31)8(cid:8)(cid:7)(cid:28)(cid:14)(cid:3)(cid:29)(cid:29)(cid:4)(cid:11)(cid:8)(cid:11)(cid:16)(cid:30)(cid:31)B(cid:3)(cid:5)(cid:5)(cid:15)(cid:14)(cid:12)>(cid:22)(cid:16)(cid:12)(cid:31)? (cid:10)(cid:23)(cid:2)$@)+5’7)(*5&)4 (cid:2)(cid:5)(cid:3)%(cid:19)(cid:6)(cid:28)(cid:20)(cid:10)(cid:4)(cid:11)(cid:7)(cid:12)&(cid:16)(cid:30)(cid:10)(cid:4)(cid:10)(cid:28)(cid:8)’(cid:13)(cid:7)(cid:7)(cid:12)(cid:22)(cid:23)(cid:24)(cid:24)(cid:23) 6(cid:4)(cid:5)(cid:31)(’A(cid:31) (cid:31)(cid:23)(cid:15)(cid:6)(cid:4)(cid:21)(cid:3)(cid:8)-(cid:30)(cid:31)(cid:23)(cid:31)(cid:23)(cid:26)(cid:7)(cid:26)(cid:15)(cid:13)(cid:8)(cid:11)(cid:3)(cid:8)"(cid:8)(cid:11)(cid:16) (cid:10)(cid:23)(cid:2)$@)+5’7)(*A5)7 8(cid:31)$(cid:3)(cid:15)(cid:16)(cid:26)%(cid:3)(cid:15)(cid:16)(cid:26)(cid:3)(cid:11)(cid:12)"(cid:3)>(cid:22)(cid:16)(cid:12)(cid:31)? 6(cid:4)(cid:5)(cid:31)5A(cid:31)B(cid:31)=(cid:31)<(cid:3)(cid:11)-=(cid:31)=(cid:31)=(cid:8)(cid:4)(cid:8)(cid:11)(cid:16)<(cid:31)#(cid:31)D(cid:8)(cid:16)(cid:15)(cid:20)>(cid:22)(cid:16)(cid:12)(cid:31)? 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Duro Universidade da Corufia Escuela Politecnica Superior c/Mend.izabal s/n 15403 Ferrol (La Corufia) Spain richard @udc.es Professor Jose Santos Universidade da Corufia Departamento de Computaci6n Campus de Elvina 15701 La Corufia Spain santos @udc.es Professor Manuel Grana Universidad del Pafs Vasco, UPV/EHU Departamento de Ciencias de la Computaci6n e Inteligencia Artificial 20018 San Sebastian Spain ccpgrrom @sc.ehu.es ISSN 1434-9922 ISBN 978-3-7908-2517-6 ISBN 978-3-7908-1775-1 (eBook) DOI 10.1007/978-3-7908-1775-1 Library of Congress Cataloging-in-Publication Data applied for Die Deutsche Bibliothek - CIP-Einheitsaufnalune Biologically inspired robot behavior engineering I Richard J. Dnro ... ed. - Heidelberg; New York: Physica VerJ., 2003 (Studies in fuzziness and soft computing; Vol 109) This work is subject to copyrighL All rights are reserved, whether the whole or part of the material is con cerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, repro duction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Physica-Verlag. Violations are liable for prosecution under the German Copyright Law. ©Springer-Verlag Berlin Heidelberg 2003 Originally published by Physica-Verlag Heidelberg New York in 2003 Softc over reprint of the hardcover 1st edition 2003 The use of general descriptive names, registered names, tradernms, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and tegulations and therefore free for general use. Printed on acid-free paper "Was the Setaur intelligent? Well yes, in its own fashion! That "unnecessary" -and at the present moment highly dangerous- "wisdom" of the machine angered many participants in the action; they couldn't see why in the hell the engineers had endowed such freedom and autonomy on a machine made strictly for mining tasks. McCork calmly explained that this "intellectronic redundancy" was - in the current phase of technological development- the same thing as the excess of power generally found in all conventional machines and engines: it was an emergency reserve, put there in order to increase safety and dependability off unction. There was no way of knowing in advance all the situations in which a machine, be it mechanical or informational, might find itself. And therefore no one really had the foggiest notion of what the Setaur would do." The Hunt, p. 156 in Stanislaw Lem, Mortal Engines, Orlando, Fla: Harcourt Brace Jovanovich 1992 Preface Engineering is concerned with the construction of artificial objects that accomplish some required task or fulfill some needed function. This book is primarily about engineering in the sense that its contents deal with artificial objects and some specific ways to conceive and construct them. On the other hand, it strays from the general mainstream in this field in the methodological aspects of the design process. The general kind of objects considered here belong to the branch of robotics defined as "mobile robotics" or, in a more general definition, "autonomous robotics". This type of systems share many engineering features with other machines and robots, but differ from traditionally engineered ensembles in that, irrespective of their final function, they must carry out this function as independently as possible from human supervision, even under changing environmental and/or internal conditions. Thus, a higher design level not contemplated for most machines that involves certain capabilities such as adaptability, learning, behavior modification and fault tolerance, among others, is needed. Design at this level introduces requirements that are very hard to state precisely and in conventional methodological engineering terms about how to learn, what is important in an environment, what is the relationship between body and function, etc. Consequently, many researchers in this field have resorted to biology for inspiration. Biological agents are autonomous and manage to survive in their ecological niches. Therefore, we can draw some ideas from them on how to obtain different types of behaviors and on the structures that are required for autonomy. Conversely, by implementing what we think are biological concepts on VI artificial systems and combining them with more traditional engineered solutions we can gain insight into how biological systems work and relate to their environment. The words "Biological Inspired Engineering" have a multitude of meanings, of which the contents of the present book are a privileged sample. The backgrounds of the authors contributing to this volume encompass a broad spectrum of fields, and therefore their views on the area reflect this variety. Some are in the biological sciences trying to replicate biological behaviors, while others belong to more classical engineering fields and are more interested in efficiency questions: efficient design, efficient control, and efficient computation. Still others are in the nebulous area between the established scientific fields. Biological inspiration may affect The object itself, The purpose of the construction of the object, The construction methodology, The building blocks for the objects. We would like to provide a neat classification of the work contained in this book, but it is not possible, as is often the case with fast evolving research areas. Nevertheless we can consider the above list as possible axes in an abstract graph that allows us to locate the contributions and to relate them. The object: The physical design of the robot may be heavily influenced by biology: grasping hands, legged insect-like robots, etc. In this volume, two exotic designs are studied: the swimming lamprey-like robot (Chs. 1 and 4) and the brachiation robot (Ch. 2). Other authors consider more conventional legged and/or wheeled robots (Chs. 1, 6 and 9) and some take as the object of their study individual subsystems, proposing different solutions to enhance sensing or actuation capabilities (Chs. 5 and 12 to 15). Finally, the robot morphology used to test the ideas under development may be closely entwined with theory and condition its shape. i.e.: Ch. 6 makes an explicit effort to abstract from the Khepera robot, but is still conditioned by its broad morphological features. The purpose: Some papers deal with the modeling of biological entities and try to obtain new insights through the simulation, analysis and parameter optimization of their artificial counterpart (Chs. 2, 3, 4 and 11). However, in this same volume other authors strive to solve very precise technological problems (Chs. 12 to 15). Others (Chs. 1, 9) fall in a nebulous region where the results may be interpreted from a biological perspective and have a technological value. They are not concerned with the existence of a biological VII counterpart, they profit from the biological metaphor in terms of the power and flexibility that is derived from it. The work on lamprey swimming robots reflects the divergence in purposes that may be characteristic of the field and the contents of this book. While the authors in Ch. 4 aim to learn about the dynamic implications of Ekeberg's model parameter settings, the authors of Ch. 1 seek the spontaneous generation of the control structure and parameter settings, following a general methodology that is also applied to other robot types. The design methodology: Automatic robot design implies some kind of optimization process, either for parameter estimation or for structural design. Evolutionary Algorithms are becoming the standard tool for these processes and most of the chapters involve their use in some way or another. The reason lies in the enormous modeling flexibility allowed by coding the problem into individual genotypes and the fact that some guarantees of convergence are conveyed by the use of these algorithms. Finally, it is usually easy to obtain relative performance values for complex robots operating in different environments, which is what an evolution based algorithm requires, but very hard to provide the exact gradient or error values needed by other types of optimization techniques. Notwithstanding this fact, in some cases the parameter estimation can be achieved by simple techniques, such as gradient descent algorithms. The building blocks: Some neural architectures have become standard tools for data fitting and modeling: Self Organizing Maps (SOM), Multiple Layer Perceptrons (MLP), etc. Given the fact that data clustering and categorization pervades the autonomous learning paradigm, competitive neural networks are present in many control system designs (Chs. 6, 8, 11 and 12). However, there is still room for some recent neural networks (Ch. 13) or derivations of traditional networks, such as those including trainable delayed connections (Ch 9). We have included within the scope of biologically inspired some computational models such as fuzzy modeling (Ch. 2 and 15), inspired on the "computation with words" ability of humans; and regular grammars for syntactic modeling and synthesis of (control) structures (Ch. 1). VIII Questions This book poses rather than solves a number of questions. These questions are defining the boundary of research in this area and the contributions included in this book are motivated by the quest for answers to some or all of them. Autonomy What are the limits and conditions of achievable autonomy? Autonomy is the key term in this volume and in the whole area of robotics. The goal is to obtain systems that work without human intervention. The Autonomy question can be stated in another way: When is the Deus ex machina required to restart the processes or to correct undesired or unstable behaviors?. Truly autonomous systems will never need the intervention of the God like supervisor. The degree of intervention required for the system to work is a negative measure of autonomy. There are several degrees of autonomy that are easily acknowledged by the scientific community: Autonomous behavior: how long does the robot live by itself? Autonomous adaptation: To what degree is the robot able to change itself to survive? We can distinguish between the following: • Parameter fitting. • Strategy learning. • Morphological adaptation The ultimate goal is to propose systems that, starting from the zero structural state, learn the optimal control structure and parameter settings to cope with a specified task in a given (noisy) environment. However, the unavoidable teacher appears most of the time in the form of an objective function or some kind of reward (reinforcement). Even unsupervised systems hide some implicit type of supervision in the computation of the objective function. Although the length of the active life is the basic measure of autonomy, there are few studies that involve the duration of the life cycle of the robot. Those studies that exist need to provide complete strategies for robot refurbishment and "feeding" and to define appropriate environments. Some studies found in the literature, introduce hunger as the driving force for the robot and measure fitness of the individual by its length of life. These studies seldom wander off the simulation desk. They do, however, provide a way to obtain some degree of autonomy, at least in the form of a short life before starving. In this volume only Ch. 11 gives some lateral consideration to this issue. Some of the authors found in this volume, (Chs. 1, 3, 4 and 9) build (often by means of evolutionary algorithms for parameter optimization) their systems IX offline, out of the real-life operation loop. Life is an experiment that is restarted each time, in an infinite trial and error process. Although some kind of evolutionary algorithm implements the search process, there is no truly autonomous breeding and selection in a closed environment. We can distinguish two cases of autonomous parameter fitting. The first corresponds to systems that perform some type of on-line learning or "learning while performing". Ch. 2 estimates the parameters of its brachiation controller during operation. Ch. 8 proposes a neurocontrol architecture with some ability to learn and categorize new sensorial data to integrate the desired behaviors. Others, such as Chs. 12, and 13, propose visual information processing schemes intended for adaptation during the real-time operation of the robot. Ch. 10 also proposes on-line learning once the control structure is set. The second case of autonomous parameter fitting corresponds to the consideration of non-stationary environments. Changing environments imply changing sensory conditions as well as structural conditions. It is not only the map of the world that may change. The lighting conditions may affect the camera or the infrared proximity sensors. Also the internal state of the system may change, e.g. batteries drain and so motors reduce their response to control commands. In Ch. 5 the author claims that his system is naturally adapted to external changes, given that the model of the world is embedded in the neural structure. Ch. 12 considers the robustness of non-stationary image capture implicit in the adaptation performed by the competitive neural networks that compute the filtered image. The second and third levels of autonomous behavior are subjects of active research. Ch. 11 induces control structures from sensory motor interaction with the goal of obtaining high-level control structures, i.e. planning. However an example of strong structural adaptation is lacking. Generality Is there any kind of no-free lunch theorem for computational intelligence in autonomous systems? Traditional robotics is based on the mathematics of (linear) control theory and mechanical modeling. The power of these formal tools to face real life problems has been extensively proven, and also their limitations. Biologically inspired modeling and design tools have been proposed as a way to overcome these limitations, but the question remains: Is it possible to propose a general design strategy and general modeling tools for autonomous (robotic) systems? At any level, adaptation implies some kind of optimization process, which sometimes (but not always) can be formalized. The translation of the no-free lunch theorem, already formulated for optimization problems to the design of autonomous systems, means that no general strategy defined in an absolute way would be X applicable to every situation. Research in this line must include work on defining the range of applicability of the proposed tools. The work of Ch. 1 addresses the formulation of a general design strategy that may be easily transported from one problem space to another. Modeling is based on the definition of a given grammar structure that must be tailored to the problem at hand. Ch. 9 provides another view on this issue, studying the reusability of control modules that perform precise behaviors. Chs. 6, 10 and 11 propose general control architectures, but they are still very conditioned by robot morphology. It is not an easy task to translate them to other robot-environment-task settings. Sensing versus control Poor sensing (i.e. infrared) needs sophisticated information processing, such as the time integration shown in some of the virtual sensors of Ch. 9, or some means of noise reduction, as in the work presented in Ch. 1 on obstacle avoidance of the rolling robot. Rich sensing (i.e. vision) overcomes the complexities of the post-processing, but it is much more expensive to obtain and process the information provided by the sensor. Ch. 5 proposes a flexible neural planning system, which relies on a very exhaustive observation of the environment. Propioceptive sensing in the form of wheel revolution counting, as in the case presented by Ch. 11, is the most basic sensing that must be considered for localization and orientation. The mixture of several sensory channels, i.e. propioceptive and visual, is a new and promising venue of research under the name of "sensor fusion". Chapters 6 and 11 introduce propioceptive sensing for enhanced control architectures. The quantization of the input sensor values, or their categorization, is a central problem in many approaches. This quantization is a means to assign numerical values to the input and allows for further processing in the control modules. Ch. 8, 10 and 11 make extensive use of quantization via competitive neural networks. Ch. 7 poses the interesting problem of the interdependence of task definition, sensing and internal control and tries to set the basis to elucidate when sensor information time integration is really needed. Robot objective Does robot behavior have any useful meaning? What are the tasks that can be learnt autonomously? The distinction between artificial life and robotics lies in the (external) definition of the utility obtained from the robots behavior. Artificial life does not expect any reward from the robots behavior, whilst roboticists focus on the utility of robot behavior. Robotics talks about "tasks" whilst artificial life talks about "behaviors" and mechanisms of reproduction. The chapters in this volume smoothly traverse the