Meeting Abstract

34-8   08:45 - 09:00  Gliding lizards crashing-landing head-first into tree trunks emulated by soft robots with active tail reflexes Siddall, R; Byrnes, G; Full, R; Jusufi, A*; Max Planck Institute for Intelligent Systems, Stuttgart, Germany; Siena College, NY; U.C. Berkeley, Berkeley, CA; Max Planck Institute for Intelligent Systems, Stuttgart, Germany ardian@is.mpg.de http://bio.is.mpg.de

Diverse solutions are known for alighting on vertical surfaces. Here we show the perching of the Asian flat tailed gecko, Hemidactylus platyurus. High-speed video footage in the Southeast Asian rainforest capturing the subcritical, short-range glides revealed that geckos did not substantially reduce speed before impact. Unlike specialized gliders, geckos experienced hard landings with front legs and head with a tree trunk at 6.0 ±0.9m/s (over 120 snout vent lengths per second). Geckos were still accelerating prior to alighting in some glides. This headfirst impact imparts a large amount of pitching angular momentum to the animal, as their head and torso pitches head over heels up to 130° away from the tree trunk anchored by only their hind limbs and tail. By using their tails to create a long moment arm, geckos are able to gradually dissipate this momentum by pitching back, and ultimately alight successfully with reduced forces. We have termed this remarkable maneuver the ‘Fall Arresting Response’ (FAR). Mathematical modeling of the dynamics pointed to the utility of tails for the FAR upon landing. Here we test predictions by measuring foot forces during landing of a soft, robotic physical model with an active tail reflex triggered by forefoot contact. As in the geckos' FAR, perching success was found to be greater for tailed robots. Experiments revealed that longer tails and an active tail reflex resulted in the lower adhesive foot forces necessary for stabilizing successful landings, with a tail shortened to ¼ of body length requiring over twice the adhesive foot force. Multiple coordinated tail reflexes, such as FAR, appear required for the most successful gliding and landing robustness in animals and robots.