ETH Zurich Team Develops Collision-Resilient Flexible Drone 'FlexiQuad'

Researchers at ETH Zurich (Swiss Federal Institute of Technology) have developed a new type of drone called FlexiQuad, characterized by its deformable rather than rigid body structure. The design aims to address the vulnerability of traditional multirotor drones to crashes and damage in complex environments.

FlexiQuad features a ring-shaped frame made of flexible glass-fiber composite strips, with batteries and propulsion units distributed evenly under the rotors instead of being centrally located. This architecture utilizes 'anisotropic stiffness': the frame deforms horizontally to absorb impact energy but remains stiff vertically to transmit the forces necessary for flight.

To recover stability after a collision, the research team used reinforcement learning to simulate countless crash scenarios, training the drone to rely on motion sensors to dampen vibrations and autonomously restabilize its flight attitude. According to an ETH Zurich press release, despite its soft body, FlexiQuad can reach speeds of up to 80 km/h and achieves accelerations comparable to traditional rigid drones.

Led by Luca Girardi and Stefano Mintchev, the project has been filed for a patent and nominated for ETH Zurich's Spark Award. The technology is currently a laboratory prototype, targeting applications in narrow and obstacle-rich environments such as ship ballast tank inspections, search and rescue in collapsed buildings, and environmental monitoring in dense forests.