As engineers begin to build tiny aircraft for tasks such as military-related surveillance and post-disaster search, they are turning to nature for inspiration. Conventional aircraft designs can be scaled down only so far, but birds and bugs are a fruitful source of alternative blueprints for cheap, agile miniature flying vehicles.RoboBees, like the one shown here, could be equipped with sensors and sent out after a natural disaster to collect environmental data or search for survivors, says their creator, Robert Wood, a professor of electrical engineering at Harvard University. For now, RoboBees can’t fly unless they’re guided by stiff wires and connected to an offboard power source. But Wood says that within about three years they should be able to fly unassisted. Such small robotic insects will be vulnerable, but they should be cheap enough to send on missions in large numbers with the expectation that not all will survive.
If swarms of small aircraft are to come into wider use, they will need to look after themselves. This quadrotor, with four helicopter-type blades, can navigate independently in controlled environments. It uses twin laser scanners, motion sensors, and an onboard computer to map its surroundings and the terrain below so that it can pick a safe landing place. Its builder, Maxim Likhachev of Carnegie Mellon University, says that future craft could be given high-level commands, such as “Go explore this building,” without need for detailed directions.This hummingbird mimic can dart in and out of open doorways in an urban environment, flip in midair, and hold its position against winds of up to eight kilometers per hour. It was developed by defense contractor AeroVironment of Monrovia, California, to meet a call by the Defense Advanced Research Projects Agency for a small, agile reconnaissance craft. It can fly for 11 minutes, directed by a pilot using a live video stream from the camera visible on the hummingbird’s chest.The wings of the SmartBird, built by the German robotics company Festo, closely mimic those of the seagull, from their two-meter span to their ability to twist for agility. While airplanes have separate structures and systems for lift, propulsion, and control, birdlike wings must handle all three at once. The SmartBird’s wings twist as they flap up and down; varying the twist controls the flight. Bird-like designs are able to switch between soaring to conserve energy and flapping for takeoff and other maneuvers.Instead of working to build and control robotic insects, Michel Maharbiz and collaborators at the University of California, Berkeley, hijacked the real thing. This six-centimeter-long flower beetle is fitted with electronics that stimulate its brain and flight muscles. Signals delivered by radio waves command its flight. Maharbiz is working on miniaturizing the electronics to control smaller insects, such as houseflies.The DelFly Micro, pictured above next to a one-euro coin, is the smallest flapping-wing craft capable of free flight while carrying a camera and a wireless transmitter. It has a wingspan of 10 centimeters and weighs three grams. The team responsible for the DelFly, at Delft University of Technology, in the Netherlands, has achieved superior control by combining flapping wings with a conventional airplane-style tail.