By Olivia Solon

Researchers at the Swiss Federal Institute of Technology have developed quadrocopters that can be controlled with such precision that they can play tennis.

The quadrocopters — fitted with a taut mesh, akin to the head of a tennis racket — were able to return a ball to someone who threw it to them by moving forward, angling the racket toward them. Two of the quadrocopters were also able to play an extended rally of tennis with each other, swiftly positioning themselves to return the ball to the other robot. A single quadrocopter could also play a game of “keepie-uppie” with the ball without dropping it.

The robots are based on the “Hummingbird” quadrocopter designed by Ascending Technologies, but the on-board controls have been replaced with customized electronics developed at the institute, allowing for better control over the movements of the vehicles.

There are motion-capture cameras which track the quadrocopters from above. When the person throws the ball, it’s tracked by the camera, and a specially written program works out where the ball is going to go. The program then maneuvers the vehicle accordingly, angling it so it bounces toward the thrower.

The same vehicles have been used to execute complicated maneuvers such as flips, as well as synchronized choreography to music.

Mark Müller, Sergei Lupashin and Raffaello D’Andrea from the Institute for Dynamic Systems and Control worked together to demonstrate high-performance adaptive maneuvers with the flying robots in the Flying Machine Arena, a testing area optimized for flight.

The Arena is a 10-meter-by-10-meter (33-foot-by-33-foot) space with nets on three sides and a transparent, reinforced glass wall on the fourth to create an enclosed space where autonomous vehicles can fly safely. An impact-absorbing foam makes sure the flying robots don’t damage themselves too much on impact.

This story was originally published by Wired UK.