Mexican Jumping Bean Robots Rock and Roll
Robots are often built to imitate animals' amazing feats. Among the hundreds designed, there's a gecko-inspired machine that climbs walls and one based on cockroaches that can do flips. Now a team at the Georgia Institute of Technology has turned to the Mexican jumping bean to help build robots that don't need legs and can operate with simpler instructions and less battery power.
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The Mexican jumping bean isn't a bean; it's a large seed with a moth larva growing inside. The larva climbs around inside the seed to make it roll. When the larva hits the inside wall of the seed hard with one end of its body, the seed jumps. All this rolling and jumping is to help the larva seek out a cooler location when the temperatures get too warm outside. (After about six to eight months, the larva turns into a moth and leaves the seed).
Mechanical engineers Daniel West, Ishan Lal, Michael Leamy and David Hu studied the motions of larvae, putting several of them in a kind of racetrack with a hot end and a cool end. The larvae all tried to get to the cooler area. They found a definite pattern in the movements: the beans jumped 85 percent of the time, rolled 14 percent of the time and flipped 1 percent of the time.
The scientists then wrote an algorithm to control a wheeled robot's movement that incorporated similar rules: tumble randomly to the left or right, go in the direction of lowest sensed temperature and stop moving after reaching a preset temperature.
Robots like this could make inexpensive sensors, since a cluster of bean-sized robots could be scattered and give a more complete picture of temperature differences in a given area. It's also possible to program a different kind of gradient; one might use light or a chemical in the air. Such simple algorithms don't need the processing power that more complicated locomotion does, and as such, it saves both space and power.
The study appears in the journal Bioinspiration & Biomimetics.
Image: Wikimedia Commons