“Two of the most challenging problems tackled with quadrocopters so far,” says Markus Waibel at Robohub, “are balancing an inverted pendulum and juggling balls.” It’s not clear to me why those are problems that need to be solved, but I’m glad the team at ETH Zurich’s Flying Machine Arena is working on them, because this video is awesome. “Inverted pendulum” refers to a balancing act, like a clown balancing a chair on his chin–these quadrocopters are tasked with balancing a very tall, straight pole, while flying. And then they’re tasked with tossing that pole to each other.

This is an autonomous project; the quadrocopters recalculate the pole’s balance and trajectory a whopping 50 times per second in order to perform this highly difficult trick. And considering the total time between a throw and a catch of the pole is only 0.65 seconds, the quadrocopters have very little time to analyze and adjust.

Check out the details over at RoboHub, where they lay out all the challenges involved in the trick (and there are many). Or, just watch that video a few more times.