UNLEASHED, ROBO-INSECT TAKES FLIGHT
years now, scientists have sought to build aerial robots inspired by bees and other flying insects. But they have always run into a fundamental problem: Flying takes a lot of energy.
Insects flap their wings, generating the thrust needed to move through the air by utilizing the energy stored in strong muscles. Their robot doppelgängers must rely on batteries, which are less efficient and tend to be heavy, or must be hooked up externally.
Now researchers at Harvard University have built a new type of robot that is capable of true, untethered flight. The unit, called the RoboBee X-Wing, is equipped with four tiny wings made of carbon fiber and polyester, and even tinier photovoltaic cells.
In bright light, its solar cells generate about 5 volts of electricity, which a minuscule transformer then boosts to the 200 volts necessary for liftoff. When the high voltage is applied to two components called piezoelectric actuators, they bend and contract, much as an insect’s muscles would. This drives the flapping motion of the RoboBee’s wings.
Clever engineering keeps the device small and light — about one-quarter the weight of a paper clip. This allows the RoboBee to flit about freely, whereas previous iterations of the robot could only take off, land, or perch midflight while leashed to a power supply.
“We wanted to keep pushing the limit on how much power we could squeeze out of the artificial muscles in the robot, and how efficient we could make the whole system,” said Noah Jafferis, a postdoctoral engineer at Harvard and one of the leaders of the research.
Last month, Jafferis and his colleagues reported in Nature that the RoboBee is now able to match the thrust efficiency of similarly sized insects, such as bees.
So far, each of the RoboBee’s test flights have only lasted a couple seconds. One of the robot’s shortcomings is that it still can’t store energy. As soon as it flies out of a small, well-lit area, it slows down and falls to the ground.
But Helbling and Jafferis are confident that the robot could stay aloft for several minutes if its solar cells and circuits were given the proper tweaks.