Reacts in a split second This drone wins at dodgeball

Die Drohne kann erfolgreich auszuweichen – sogar wenn der Ball aus drei Metern Entfernung mit 10 m/s auf sie zukommt.
The drone can sidestep quickly - even if the ball is approaching it at 10 m/s from a distance of three metres.

Drones are not very good at avoiding obstacles - especially when they are moving fast. Scientists at the University of Zurich have developed a new type of camera technology that can help.

Although many flying robots have cameras that detect obstacles, it usually takes 20 to 40 milliseconds for the drone to respond. This sounds fast, but is not enough to avoid a bird or another drone. This causes problems when many drones are flying at the same time or the environment is unpredictable.

That's why the research group...

... "Robotics and Perception" at the UZH Institute of Computer Science equipped a quadrocopter (drone with four propellers) with special cameras and algorithms, thus reducing the reaction time to a few milliseconds - short enough to avoid a ball thrown from a short distance. "In search and rescue missions, such as after an earthquake, the time factor is very critical. That's why we need drones that navigate as fast as possible to achieve more with the limited life span of their batteries," says Davide Scaramuzza, who heads both the Zurich research group and the Rescue Robotics Grand Challenge of the National Centre of Competence in Research (NCCR) Robotics. "However, fast navigating drones also have a higher risk of colliding with obstacles, especially when they are moving. We recognized that a new type of camera, a so-called event camera, is perfectly suited for such applications."

Conventional video cameras...

...for example in smartphones, regularly take snapshots of the entire scene by exposing all pixels simultaneously. However, a moving object is only detected when all pixels have been analyzed. Event cameras, on the other hand, have intelligent pixels that work independently of each other: Only the pixels that detect a change in light intensity immediately send out information, the others remain silent. This speeds up processing considerably. Because event cameras are a new invention, researchers had to develop their own algorithms for use in drones. These algorithms collect all the events recorded by the camera over a very short period of time and subtract from this the effect of the drone's own movement. The signal that is then left over probably comes from a moving object.