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How Spy Flies Will Work

Micromechanical Flying Insect
An artist's concept of the completed micromechanical flying insect being developed at Berkeley
An artist's concept of the completed micromechanical flying insect being developed at Berkeley
Photo courtesy R.Fearing/UC-Berkeley

The U.S. government has also invested $2.5 million in the Berkeley project to develop a robotic insect the size of a common housefly. The first major step toward getting this micromechanical flying insect (MFI) in the air was the development of Robofly, which gave researchers important insight into the mechanisms of insect flight.

In order to build the MFI, researchers performed experiments to learn how flies fly. One of the experiments involved building a pair of 10-inch (25-cm) robotic wings, called Robofly, which was made of Plexiglass and modeled after the wings of a fruit fly. The wings were immersed in a tank of mineral oil, which forces them to react like smaller, 1-millimeter-long fruit-fly wings beating rapidly in the air. Six motors -- three on each wing -- moved the wings back and forth, up and down and in a rotary motion. Sensors were attached to measure the force of the wings.

Eventually, the Robofly will be shrunk down to a stainless-steel microrobotic fly that is 10 to 25 millimeters (0.4 to 1 inch) in width and weighs roughly 43 milligrams (0.002 ounces). The wings will be made of a thin Mylar film. Solar power will run a piezoelectric actuator that will push the wings to flap. The robot's thorax will transform piezoelectric-actuator deflections into the large wing stroke and rotation required to achieve flight.

Although the robot does not yet fly, it's been reported that approximately 90% of the force required for lift has been achieved experimentally with a fully operational, two-wing structure. The next step will be to add a flight-control unit and communication unit for remote control. The researchers say that they are working on enabling controlled hovering by way of optical sensing and an onboard gyroscope.