Friday, March 20, 2020

This drone can play dodgeball—and win

MARCH 19, 2020, by University of Zurich
https://techxplore.com/news/2020-03-drone-dodgeballand.html

The drone is able to successfully dodge - even if the ball is approaching it from a distance of three meters at 10 m/s. Credit: UZH

Using a novel type of cameras, researchers from the University of Zurich have demonstrated a flying robot that can detect and avoid fast-moving objects. A step towards drones that can fly faster in harsh environments, accomplishing more in less time.

Drones can do many things, but avoiding obstacles is not their strongest suit yet—especially when they move quickly. Although many flying robots are equipped with cameras that can detect obstacles, it typically takes from 20 to 40 milliseconds for the drone to process the image and react. It may seem quick, but it is not enough to avoid a bird or another drone, or even a static obstacle when the drone itself is flying at high speed. This can be a problem when drones are used in unpredictable environments, or when there are many of them flying in the same area.

Reaction of a few milliseconds

In order to solve this problem, researchers at the University of Zurich have equipped a quadcopter (a drone with four propellers) with special cameras and algorithms that reduced its reaction time down to a few milliseconds—enough to avoid a ball thrown at it from a short distance. The results, published in the journal Science Robotics, can make drones more effective in situations such as the aftermath of a natural disaster.

"For search and rescue applications, such as after an earthquake, time is very critical, so we need drones that can navigate as fast as possible in order to accomplish more within their limited battery life," explains Davide Scaramuzza, who leads the Robotics and Perception Group at the University of Zurich as well as the NCCR Robotics Search and Rescue Grand Challenge. "However, by navigating fast drones are also more exposed to the risk of colliding with obstacles, and even more if these are moving. We realized that a novel type of camera, called Event Camera, are a perfect fit for this purpose".

Event cameras have smart pixels

Traditional video cameras, such as the ones found in every smartphone, work by regularly taking snapshots of the whole scene. This is done by exposing the pixels of the image all at the same time. This way, though, a moving object can only be detected after all the pixels have been analysed by the on-board computer. Event cameras, on the other hand, have smart pixels that work independently of each other. The pixels that detect no changes remain silent, while the ones that see a change in light intensity immediately send out the information. This means that only a tiny fraction of the all pixels of the image will need to be processed by the onboard computer, therefore speeding up the computation a lot.

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