Folding drone holds promise for search and rescue applications

An experimental folding drone, able to retract its arms during flight and make itself small enough to fit through narrow gaps and holes, could have great potential for search and rescue operations it is claimed.

folding drone
When faced with a narrow passage, the drone can switch to a “H” shape, with all arms lined up along one axis. (Image: UZH)

Developed by a team from the Robotics and Perception Group at the University of Zurich and the Laboratory of Intelligent Systems at EPFL (Ecole polytechnique fédérale de Lausanne) the drone takes its inspiration from the way in which birds are able to fold their wings in mid-air, and is able to squeeze itself to pass through gaps during flight.

The group claims that the folding drone could enter buildings through gaps which are too narrow for conventional drones be used to look for people trapped inside and guide the rescue team towards them.

“Our solution is quite simple from a mechanical point of view, but it is very versatile and very autonomous, with onboard perception and control systems,” explained Davide Falanga, researcher at the University of Zurich and author of a paper on the project published in IEEE Robotics and Automation Letters 

The Zurich and Lausanne teams worked in collaboration and designed a quadrotor with four propellers that rotate independently, mounted on mobile arms that can fold around the main frame thanks to servo-motors. The control system adapts in real time to any new position of the arms, adjusting the thrust of the propellers as the centre of gravity shifts.

“The morphing drone can adopt different configurations according to what is needed in the field,” said co-author Stefano Mintchev. The standard configuration is X-shaped, with the four arms stretched out and the propellers at the widest possible distance from each other. When faced with a narrow passage, the drone can switch to an “H” shape, with all arms lined up along one axis or to an “O” shape, with all arms folded as close as possible to the body. A “T” shape can be used to bring the onboard camera mounted on the central frame as close as possible to objects that the drone needs to inspect.

The researchers are now looking at further improving the folding drone structure so that it can morph in all three dimensions. They also plan to develop algorithms that will make the drone truly autonomous, allowing it to look for passages in a real disaster scenario and automatically choose the best way to pass through them. “The final goal is to give the drone a high-level instruction such as ‘enter that building, inspect every room and come back’ and let it figure out by itself how to do it,” said Falanga.