"Flying 3D eye-bots" can be deployed as additional surveillance resources during major events, or as high-resolution 3D street imaging systems. These unmanned aerial vehicles (UAVs) are a kind of mini-helicopter, with a wingspan of around two meters. They have a propeller on each of their two variable-geometry side wings for rapid and precise maneuverability. A CMOS sensor developed by researchers at Germany's Fraunhofer Institute for Microelectronic Circuits and Systems IMS lies at the heart of the flying robot's anti-collision technology. “The sensor can measure three-dimensional distances very efficiently,” says Werner Brockherde, head of the development department. The eye-bots are capable of identifying small objects measuring 20 by 15 centimeters at ranges of up to 7.5 meters.

The 3D distance sensors are built into cameras manufactured by TriDiCam, a spin-off company of Fraunhofer IMS. Even when there is interfering light - for example when a drone is flying directly into the sun - the sensor will deliver accurate images. It operates according to the time-of-flight (TOF) process, whereby light sources emit short pulses that are reflected by objects and bounced back to the sensor. To prevent over-bright ambient light from masking the signal, the electronic shutter only opens for a few nanoseconds. The sensor also takes differential measurements, in which the first image is captured using ambient light only, a second is taken using the light pulse as well, and the difference between the two determines the required output signal.

Whether deployed to create virtual maps of difficult-to-access areas, to monitor construction sites, or to measure contamination at nuclear power plants, these mini UAVs could potentially be used in a wide range of applications, obviating the need for expensive aerial photography and/or satellite imaging.