Flying robots cooperate to play catch


September 29, 2012

Flying quadrocopters at ETH Zurich's Flying Machine Arena catch and launch a ball using a net spread between them

Flying quadrocopters at ETH Zurich's Flying Machine Arena catch and launch a ball using a net spread between them

Image Gallery (3 images)

Swiss researchers have published a new video showcasing the impressive aerial cooperation capabilities of robotic quadrocopters. In the demonstration, a trio of quadrocopters tethered to a net fly in formation to catch balls tossed at them. Once they've caught the ball in the net, they are able to launch it upwards by stretching the net at each end.

"To toss the ball, the quadrocopters accelerate rapidly outward to stretch the net tight between them and launch the ball up. Notice in the video that the quadrocopters are then pulled forcefully inward by the tension in the elastic net, and must rapidly stabilize in order to avoid a collision. Once recovered, the quadrotors cooperatively position the net below the ball in order to catch it." explained Robin Ritz, Lead Researcher at ETH Zurich’s Flying Machine Arena.

"Because they are coupled to each other by the net, the quadrocopters experience complex forces that push the vehicles to the limits of their dynamic capabilities. To exploit the full potential of the vehicles under these circumstances requires several novel algorithms, including:

  • an optimality-based real-time trajectory generation algorithm for the catching maneuver;
  • a time-varying trajectory following control strategy to manage the forces on the individual vehicles that are induced by the net; and
  • learning algorithms that compensate for model inaccuracies when aiming the ball.
  • "

    See this unique aerial display in the video below. You can also check out this earlier video of flying robots building a tower block by block.

    Source: ETH Zurich Flying Machine Arena via Robohub

About the Author
Jason Falconer Jason is a freelance writer based in central Canada with a background in computer graphics. He has written about hundreds of humanoid robots on his website Plastic Pals and is an avid gamer with an unsightly collection of retro consoles, cartridges, and controllers. All articles by Jason Falconer


Mark Smith

Wow, that is incredible programming. Extremely difficult to do, and they have nailed it. Such programming will be essential for a future where miniaturised robots will be used to save lives (Fire and rescue), or do recon (military). Can't wait to see this kind of tech being used in real-world applications.

Brendon Walker

I see a time in the not-too-distant future when UAV countermeasures become an important part of the domestic security industry. Whats that buzzing sound I keep hearing?


Switzerland continues to amaze us, great piece of pure Tech fun! But have you considered one day, a swarm of such groups, but of much larger quadrocopters, catching people falling from buildings?

Edgar Castelo this is how Skynet gets started!


When you suspend a load from a crane there are dynamic effects of the rope swinging, and that's a large part of the crane operator's skill is to dampen out the swinging and keep the load under control. It's one of those skills that takes a lot of experience to develop the "feel" and become really proficient at it, to the point you can become safe handling loads around people. If a UAV can become proficient with handling a suspended load, of an arbitrary weight at an arbitrary length, then that is an impressive technological leap. There are several tragic videos on youtube of heavy-lift helicopter cranes losing control and crashing their load and killing everybody on board - it would be a real leap forward to eliminate this operator risk by automation.


There is a design of space elevator using a cable rotating in Low Earth Orbit (LEO) . The purpose of which is to catch objects carried by fast aircraft and launch them into space. The software for this could be developed from the above demonstration.

Stephen Colbourne
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