Tm. Kubow et Rj. Full, The role of the mechanical system in control: a hypothesis of self-stabilization in hexapedal runners, PHI T ROY B, 354(1385), 1999, pp. 849-861
Citations number
27
Categorie Soggetti
Multidisciplinary,"Experimental Biology
Journal title
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES
To explore the role of the mechanical system in control, we designed a two-
dimensional, feed-forward, dynamic model of a hexapedal runner (death-head
cockroach, Blaberus discoidabis). We chose to model many-legged, sprawled p
osture animals because of their remarkable stability. Since sprawled postur
e animals operate more in the horizontal plane than animals with upright po
stures, we decoupled the vertical and horizontal plane and only modelled th
e horizontal plane. The model was feed-forward with no equivalent of neural
feedback among any of the components. The model was stable and its forward
, lateral and rotational velocities were similar to that measured in the an
imal at its preferred velocity It also self-stabilized to velocity perturba
tions. The rate of recovery depended on the type of perturbation. Recovery
from rotational velocity perturbations occurred within one step, whereas re
covery from lateral perturbations took multiple strides. Recovery from fore
-aft velocity perturbations was the slowest. Perturbations were dynamically
coupled-alterations in one velocity component necessarily perturbed the ot
hers. Perturbations altered the translation and/or rotation of the body whi
ch consequently provided 'mechanical feedback' by altering leg moment arms.
Self-stabilization by the mechanical system can assist in making the neura
l contribution of control simpler.