Meeting Abstract
Animals can synergistically employ multiple appendages and body segments to perform behaviors. We hypothesize that these controllable components can be represented by sets of simple models (templates) that can be recruited in series or parallel to provide multiple strategies for executing a maneuver. To further define our conjecture, we measured self-righting in geckos, H. frenatus, on flat, rigid surfaces. Geckos self-righted successfully with average righting times of 0.22±0.03 s using complex dynamic appendage and body motions including body bending/torsion, limb/tail ground contact, and coronal plane tail sweeps qualitatively similar to those observed in inertial air-righting. To attempt to isolate control modules, we allowed geckos to right on a partially excavated rigid surface, where only the torso and legs, but not the tail, could make ground contact. Geckos still righted successfully without tail contact, but the average righting time increased by 40%, except when geckos used a different strategy, swinging their tails in the direction opposite to body rotation. Recruiting the tail inertial control module resulted in righting performance comparable to tail contact with average righting times of 0.19±0.02 s. Gecko body-level behavior appeared invariant to the dichotomy in tail strategy, with shoulder rotation preceding hip rotation. From these experiments, we begin to develop composable templates for quadrupedal terrestrial righting, start to validate these models through dynamic simulations, and explore possible feedback control strategies for bio-inspired robots. Our results suggest that geckos employ the tail as a multifunctional motor module in parallel with a body torsion template to increase robustness to challenging environmental substrates.
