Robot Helicopters Playing Tennis

This is not human-piloted. The vehicles/ball are tracked by an overhead motion capture system and controlled by a pair of computers. This amazing ball juggling experiment with quadrotors is at the ETH Flying Machine Arena, by Mark Müller, Sergei Lupashin and Raffaello D’Andrea at IDSC, ETH Zürich, Switzerland http://www.flyingmachinearena.org via