The authors of the research, all from the Wyss Institute for Biologically Inspired Engineering at Harvard, modeled their miniature flying robot on the Drosophila commonly referred to as fruit flies.
The tiny aerial robot is made from a carbon fiber body with polymer wings and comes in at a lightweight 80 milligrams. It has a wingspan of three centimeters or slightly larger than a U.S. quarter. Using a piezoelectric material for the robots' "muscles" it can generate 1.3 milliNewtons of upward force.
The small size lead to a few problems however. For starters, a fly houses all the components necessary for flight. The control system, power supply and mechanical structures are combined into a tiny self-contained package. The miniature robot gets it's power and controls from a wire connected to the housing. And instead of using gears, motors or rotors as would normally be the case, the wings flap when voltage is applied which changes the materials' shape.
The researchers were able to get the wings to flap at 120 beats per second which is similar to a fly's. This created a resonance which transferred to the housing and resulted in an amplification effect. Instead of changing the amount of voltage to move the robot up and down, they instead altered the wings travel distance to generate more or less lift.
Much like the sophisticated avionics control systems used in jet aircraft, the robot's flight surfaces need constant updates for it to stay aloft. In order to accomplish that, tiny silver balls were attached to the feet, providing balance, and a motion capture system calculated it's position in a three-dimensional space.
All in all, the robot is a nice demonstration of using modern materials and current technology to great effect. Nature has had millions of years to achieve the results we see today but given enough time, researchers will eventually be able to replicate and improve upon that performance.