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Rapid inversion: running animals and robots swing like a pendulum under ledges.

Mongeau JM, McRae B, Jusufi A, Birkmeyer P, Hoover AM, Fearing R, Full RJ - PLoS ONE (2012)

Bottom Line: 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 in part due to scaling.Quantification of these acrobatic behaviors provides biological inspiration toward the design of small, highly mobile search-and-rescue robots that can assist us during natural and human-made disasters.

View Article: PubMed Central - PubMed

Affiliation: Biophysics Graduate Group, University of California, Berkeley, California, United States of America. jmmongeau@berkeley.edu

ABSTRACT
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 in part due to scaling. Here, we report a novel behavior in small, legged runners that may facilitate their escape by disappearance from predators. We video recorded cockroaches and geckos rapidly running up an incline toward a ledge, digitized their motion and created a simple model to generalize the behavior. Both species ran rapidly at 12-15 body lengths-per-second toward the 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, out of sight. We discovered geckos in Southeast Asia can execute this escape behavior in the field. Quantification of these acrobatic behaviors provides biological inspiration toward the design of small, highly mobile search-and-rescue robots that can assist us during natural and human-made disasters. We report the first steps toward this new capability in a small, hexapedal robot.

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Related in: MedlinePlus

Sequence of rapid inversion behavior in a cockroach, gecko, and a robot prototype.Panels (a) and (b) show a high-speed 180-degree inversion behavior on an incline for cockroaches, P. americana and house geckos, H. platyurus, respectively. Panel (c) shows a cockroach-inspired hexapedal robot, DASH, successfully performing a similar maneuver from a horizontal platform with small Velcro hooks attached at the end of the hind legs.
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pone-0038003-g001: Sequence of rapid inversion behavior in a cockroach, gecko, and a robot prototype.Panels (a) and (b) show a high-speed 180-degree inversion behavior on an incline for cockroaches, P. americana and house geckos, H. platyurus, respectively. Panel (c) shows a cockroach-inspired hexapedal robot, DASH, successfully performing a similar maneuver from a horizontal platform with small Velcro hooks attached at the end of the hind legs.

Mentions: We discovered that American cockroaches (mass = 0.71±0.07 g, n = 6 animals, 32 trials) escaped at high speed (62.1±9.1 cm s–1) up an inclined track, dove forward and caught their tarsal claws, usually of both hind legs, on the substrate (Fig. 1a; Video S2). Data are reported as means ± s.d. unless otherwise noted. The claws briefly disengaged from the substrate as the tibia contacted the tip of the ledge, but then quickly reengaged at the tip [20]. With the claws attached, cockroaches executed a pendulum-like swing with peak head velocities of 109±12 cm s–1 (head angular velocities >1,200 deg s–1) around towards the underside of the substrate in only 127±22 ms (Fig. 2a-c). Cockroaches experienced mean peak accelerations of 3.8±0.9 Gs during the swing. After the swing, they secured their position and took several steps forward in an inverted posture. In approximately one quarter of the trials, cockroaches used a single leg to perform the maneuver without detectable changes in performance. Animals ran at full speed off the incline without requiring substantial braking. In only a few trials the animals continued to run off the ramp. Either slippage of the hind legs, loss of ground contact on the front and middle legs, or rapid change in pitch appeared to initiate the claw engagement reflex [20], suggesting active control. In all trials, the front and middle legs continued to cycle during the swinging maneuver. We attempted a balanced experimental design where we collected between 5 to 7 trials per individual.


Rapid inversion: running animals and robots swing like a pendulum under ledges.

Mongeau JM, McRae B, Jusufi A, Birkmeyer P, Hoover AM, Fearing R, Full RJ - PLoS ONE (2012)

Sequence of rapid inversion behavior in a cockroach, gecko, and a robot prototype.Panels (a) and (b) show a high-speed 180-degree inversion behavior on an incline for cockroaches, P. americana and house geckos, H. platyurus, respectively. Panel (c) shows a cockroach-inspired hexapedal robot, DASH, successfully performing a similar maneuver from a horizontal platform with small Velcro hooks attached at the end of the hind legs.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368944&req=5

pone-0038003-g001: Sequence of rapid inversion behavior in a cockroach, gecko, and a robot prototype.Panels (a) and (b) show a high-speed 180-degree inversion behavior on an incline for cockroaches, P. americana and house geckos, H. platyurus, respectively. Panel (c) shows a cockroach-inspired hexapedal robot, DASH, successfully performing a similar maneuver from a horizontal platform with small Velcro hooks attached at the end of the hind legs.
Mentions: We discovered that American cockroaches (mass = 0.71±0.07 g, n = 6 animals, 32 trials) escaped at high speed (62.1±9.1 cm s–1) up an inclined track, dove forward and caught their tarsal claws, usually of both hind legs, on the substrate (Fig. 1a; Video S2). Data are reported as means ± s.d. unless otherwise noted. The claws briefly disengaged from the substrate as the tibia contacted the tip of the ledge, but then quickly reengaged at the tip [20]. With the claws attached, cockroaches executed a pendulum-like swing with peak head velocities of 109±12 cm s–1 (head angular velocities >1,200 deg s–1) around towards the underside of the substrate in only 127±22 ms (Fig. 2a-c). Cockroaches experienced mean peak accelerations of 3.8±0.9 Gs during the swing. After the swing, they secured their position and took several steps forward in an inverted posture. In approximately one quarter of the trials, cockroaches used a single leg to perform the maneuver without detectable changes in performance. Animals ran at full speed off the incline without requiring substantial braking. In only a few trials the animals continued to run off the ramp. Either slippage of the hind legs, loss of ground contact on the front and middle legs, or rapid change in pitch appeared to initiate the claw engagement reflex [20], suggesting active control. In all trials, the front and middle legs continued to cycle during the swinging maneuver. We attempted a balanced experimental design where we collected between 5 to 7 trials per individual.

Bottom Line: 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 in part due to scaling.Quantification of these acrobatic behaviors provides biological inspiration toward the design of small, highly mobile search-and-rescue robots that can assist us during natural and human-made disasters.

View Article: PubMed Central - PubMed

Affiliation: Biophysics Graduate Group, University of California, Berkeley, California, United States of America. jmmongeau@berkeley.edu

ABSTRACT
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 in part due to scaling. Here, we report a novel behavior in small, legged runners that may facilitate their escape by disappearance from predators. We video recorded cockroaches and geckos rapidly running up an incline toward a ledge, digitized their motion and created a simple model to generalize the behavior. Both species ran rapidly at 12-15 body lengths-per-second toward the 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, out of sight. We discovered geckos in Southeast Asia can execute this escape behavior in the field. Quantification of these acrobatic behaviors provides biological inspiration toward the design of small, highly mobile search-and-rescue robots that can assist us during natural and human-made disasters. We report the first steps toward this new capability in a small, hexapedal robot.

Show MeSH
Related in: MedlinePlus