Sabine Hauert writes: GimBall is a new flying robot that can collide with objects seamlessly. Generally, flying robots are programmed to avoid obstacles, which is far from easy in cluttered environments. Instead, researchers from the Laboratory of Intelligent Systems at EPFL believe that flying robots should be able to physically interact with their surroundings. Take insects: they often collide with obstacles and continue flying afterwards. Their robot uses a passively rotating spherical cage to remain stable even after taking hits from all sides. This approach enables GimBall to fly in the most difficult places without complex sensors.