My colleagues at the ETH Zurich’s Flying Machine Arena have just released a new video. Here is what Robin Ritz, Lead Researcher on the project, has to say about it:
This video shows three quadrocopters cooperatively tossing and catching a ball with the aid of an elastic net.
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.
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:
1. an optimality-based real-time trajectory generation algorithm for the catching maneuver;
2. a time-varying trajectory following control strategy to manage the forces on the individual vehicles that are induced by the net; and
3. learning algorithms that compensate for model inaccuracies when aiming the ball.
For more information on this and related work, have a look at the Flying Machine Arena’s website or tune in to Prof. Raffaello D’Andrea’s ROBOTS Podcast interview.
Some photos of the robots in action: