Swiss researchers demonstrated three robotic quadrocopters, flying in formation and tethered to a net, playing catch with a ball. The helicopters maneuver to catch balls that are tossed to them and catch them in the net. Once they catch the ball, they launch it back by flying outward and stretching the net tight.
Robin Ritz, lead researcher, explained:
“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: 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.”
The helicopters feature “Hummingbird” quadrotors with custom on-board controls that allow for greater control over the vehicle’s dynamics and faster motion. The vehicles are programmed to automatically land on the charging platform to recharge when batteries get low.
Check out the video below.
