June 7, 2012
Cockroaches And Lizards Use Ninja-like Skills To Quickly Vanish
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Brett Smith for redOrbit.com
Graduate student Jean-Michel Mongeau and his colleagues first identified the amazing behavior while studying how roaches´ use their antennae to sense gaps and maneuver across them.
"As we made the gap wider, they would end up on the underside of the ramp," Mongeau said. "To the naked eye, it wasn't clear what was happening, but when we filmed them with a high-speed camera and slowed it down, we were amazed to see that it was the cockroach's hind legs grabbing the surface that allowed it to swing around under the ledge."
The UC Berkeley study, on which Mongeau was the lead author, appeared this week in the journal PLoS One and reinforced the cockroach´s reputation as one of nature´s top escape artists.
"Cockroaches continue to surprise us," said Robert Full, a UC Berkeley professor of biomechanics and study co-author. "They have fast relay systems that allow them to dart away quickly in response to light or motion at speeds up to 50 body lengths per second, which is equivalent to a couple hundred miles per hour, if you scale up to the size of humans. This makes them incredibly good at escaping predators."
The researchers discovered a similar behavior in lizards, particularly house geckos, which they documented using their hooked toenails to accomplish this escape technique both in the lab and in the jungle at the Wildlife Reserves near Singapore. According to Mongeau, the pendulum swing these creatures execute subjects them to 3-5 times the force of gravity, similar to what humans feel at the bottom of a bungee jump.
"This behavior is probably pretty widespread, because it is an effective way to quickly move out of sight for small animals," Full said.
In an effort to better understand the mechanism by which cockroaches perform this maneuver, the researchers teamed up with UC Berkeley engineering department to recreate the behavior using a tiny six-legged robot called DASH (Dynamic Autonomous Sprawled Hexapod).
A robotics group led by Ron Fearing, UC Berkeley professor of electrical engineering and computer science attached Velcro strips to the rear legs of the small, cockroach-inspired robot. Researchers were able to capture video that showed DASH reproducing the same behavior seen in roaches and geckos.
"This work is a great example of the amazing maneuverability of animals, and how understanding the physical principles used by nature can inspire design of agile robots," Fearing said.
"All this must be put together into a complete package to understand what goes into these animals' extraordinary maneuverability," Full said.
Aside from helping scientists understand animal locomotion, Full said these findings will go into making better robots.
"Today, some robots are good at running, some at climbing, but very few are good at both or transitioning from one behavior to the other," he said. "That's really the challenge now in robotics, to produce robots that can transition on complex surfaces and get into dangerous areas that first responders can't get into."