Flying robots cooperate to play catch

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.