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First published online August 31, 2007
Journal of Experimental Biology 210, 3209-3217 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.008367
An isolated insect leg's passive recovery from dorso-ventral perturbations
Department of Integrative Biology, University of California at Berkeley, Berkeley, CA 94720-3140, USA
* Author for correspondence at present address: Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada (e-mail: dudek{at}zoology.ubc.ca)
Accepted 2 July 2007
Cockroaches recover rapidly from perturbations during high-speed running that allows them to cross unstructured terrains with no change in gait. Characterization of the exoskeletal material properties of the legs suggests that passive mechanical feedback could contribute to the self-stabilizing behavior. We imposed large, dorsal-ventrally directed impulsive perturbations to isolated hind legs having both a fixed and free body–coxa joint and measured their recovery. We tested a frequency-independent hysteretic damping model that effectively predicted the behavior of sinusoidal oscillations of isolated legs. Leg position reached its peak amplitude within 4–6 ms following an impulse. Position was 99% recovered within 16±3.3 ms for the stiffest possible leg configuration and within 46±6.6 ms for the most compliant leg configuration. The rapid recovery supports the hypothesis that passive musculo-skeletal properties play an important role in simplifying the control of high-speed locomotion.
Key words: locomotion, biomechanics, modeling, Blaberus discoidalis