Unmanned helicopters are opening up entirely new possibilities. With the help of a 50- to 150-centimeter mini-helicopter, one can quickly discover faults in solar panels with the aid of an infrared camera, and wind energy convertors and bridges can be more easily checked.

They can be used to create spectacular aerial images for film and television, and the police can monitor major events from the air. Scientists have been able to document the penguin population in the Antarctic using a drone, and in Switzerland farmers are using the technology to detect fawns and partridges before harvesting their crops with combine harvesters. Only a few years ago, this sort of technology was used exclusively by the military.

The advantage of small helicopters with four to eight rotor-blades is their stability in the air, even in strong winds. They simply stay put on their target position. Complicated manoeuvres are not necessary with this technology - a helicopter with just one propeller. These unmanned air acrobats cost between 15,000 and 40,000 euros ($19,000 - $52,000).

Flying robots play tennis

The helicopters are not only good for taking aerial photographs and film footage. Researchers at the Technical University of Zürich (ETH) developed a small flying robot, which can make do without GPS or remote controls and using a mini-computer can independently navigate enclosed spaces.

At the Hannover Fair, researchers and students from ETH Zurich presented the possibilities and potential applications of mini-helicopters. In one presentation, two helicopters played tennis in midair - actually hitting a ball back and forth with rackets. The cameras in the helicopters detected the flying object and the computer calculated the trajectory and the swing required to hit the ball back.

Even dancing to music and precisely constructing towers are no problem for the mini-helicopters from ETH Zurich. A student hurled one of the flying robots with great force into the air in front of a stunned crowd. The four propellers whirred for a short time, then the "quadrocopter" remained calmly floating in the air.

Flying robots can also react to hand movements. With a camera lens, the flying robot detects the hand and moves in synchronization. The whole thing looks playful, but behind that is a precise steering mechanism and an enormous computer capacity, explained Fabian Müller.

The 26-year-old student has just completed his master's degree on the helicopters at ETH Zurich. "The real challenge is to hold the helicopter with stability in the air and then to develop algorithms so that we can make the helicopter do what we want to see. To that belongs the ability to launch from different paths, that they achieve feats and then that they land again when we want them to."

No deployment in contaminated areas

Above all, the potential for the deployment of mini-helicopters in disaster zones is particularly interesting. The use of robots in atomic catastrophes such as Fukushima is not far off. But until now, helicopters have hardly been used in radioactive regions, as the radioactive gamma rays are a big problem for the robot's electronics. The high-energy rays can damage sensors and circuitry, wipe saved data and render the helicopter completely out of service.

Author: Gero Rueter / hw
Editor: Ben Knight