19.6 Wednesday, Jan. 4 Rapid Inversion: Running Cockroaches, Geckos, and Robots Swing like a Pendulum under Ledges MONGEAU, J.-M.*; MCRAE, B.; JUSUFI, A.; BIRKMEYER, P.; HOOVER, A.M.; FEARING, R.; FULL, R.J.; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley; Olin College; Univ. of California, Berkeley; Univ. of California, Berkeley firstname.lastname@example.org
Escaping from predators often demands that animals rapidly negotiate complex environments. The smallest animals attain relatively fast speeds with high frequency leg cycling, wing flapping or body undulations, but absolute speeds are slow compared to larger animals. Instead, small animals benefit from the advantages of enhanced maneuverability. We report a novel behavior in small, legged runners that may facilitate their escape by disappearance from predators. Cockroaches (Periplaneta americana ) and geckos (Hemidactylus platyurus) ran rapidly at 12-15 body lengths-per-second toward a ledge without braking, dove off the ledge, attached their feet by claws like a grappling hook, and used a pendulum-like motion that can exceed one meter-per-second to swing around to an inverted position under the ledge, disappearing from an overhead view. We discovered evidence for the potential use of rapid inversion in nature. Geckos in the rainforests of Southeast Asia can run over fern leafs, engage their claws, and possibly their adhesive toe hairs, near the tip of the leaf and perform a pendulum-like swing towards the underside. This rapid inversion behaviour is inspiring design advancements of a small hexapedal robot DASH (Dynamic Autonomous Sprawled Hexapod) that begins to demonstrate this capability. We anticipate that the quantification of acrobatic behaviors in small animals will continue to provide biological inspiration resulting in small, highly mobile sentinel and search-and-rescue robots that assist us during natural and human-made disasters.