Images of a cockroach (top), a gecko (center) and a microbot (bottom) swinging… (PLoS One )
Ever wonder how cockroaches and lizards can disappear from sight so quickly. A new study by researchers at UC Berkeley indicates that they can run off a ledge at full speed, grasp the edge, and swing around to the bottom of platform or leaf and keep running, hidden from larger predators that cannot carry out such a complicated maneuver.
The discovery has inspired the development of miniature robots, or microbots, that can mimic their behavior, the team reported in the journal PLoS One.
Biologist Robert J. Full said researchers first observed the behavior when they were filming cockroaches running at high speeds up an inclined track with a gap in it. They expected the cockroaches to jump the gap and continue on up the ramp. To their surprise, however, the insects grasped the edge of the track with their hind legs and pivoted around to the bottom of the track, then continued running in the opposite direction.
Further studies in the lab and in the forests of Singapore showed that lizards such as geckos can do the same thing. The inertia of larger organisms, however, is too high for them to accomplish the feat.
Examining the geckos more closely, the team concluded that the animal's claws were more important to the maneuver than the sticky pads on its feet, which help it maneuver on walls and ceilings. When they removed the claws from the hind feet, the geckos would still attempt the maneuver but they failed it 94% of the time.
The team has been developing a cockroach-inspired six-footed microbot called DASH (Dynamic Autonomous Sprawled Hexapod). To test their findings, they glued Velcro hooks onto the hind legs of the microbot and complementary Velcro strips at the edge and bottom of a platform.
The platform was level because at the early stage of development, the microbot still slipped going uphill. The microbot, which has a mass of only 16 grams, ran along the track at a speed intermediate between that of cockroaches and geckos and successfully swung to the underside of the platform.
"Our serendipitous discovery not only helps explain why tiny animal pests we chase seem to disappear, but reveals a new behavior to escape predators in nature that inspired a robot's design," Full said. "Once again, you never know where fundamental research will lead."