Watch a swarm of drones build a rope bridge

A swarm of quadcopters has been programmed to autonomously build a secure rope bridge that can support human weight.

Michelle Starr Science editor
Michelle Starr is CNET's science editor, and she hopes to get you as enthralled with the wonders of the universe as she is. When she's not daydreaming about flying through space, she's daydreaming about bats.
Michelle Starr
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Equipped with spools of rope, the drones can autonomously build a rope structure. ETH Zurich

Research on the use of drones in search-and-rescue situations is ongoing, but there's no denying that the small, lightweight aerial vehicles have potential.

New research by a team at ETH Zurich has proven that they could help humans navigate precarious terrain, too: A team of quadrocopters has successfully built a rope bridge that is capable of bearing the weight of a human.

Moreover, to make the achievement even more stunning, the drones built the bridge autonomously, demonstrating that they are capable of building full-scale load-bearing structures without the need for human intervention.

"Except for the required anchor points at both ends of the structure, the bridge consists exclusively of tensile elements and its connections and links are entirely realised by flying machines," the team wrote in a post on the ETH Zurich Aerial Construction page.

Except for the metal scaffold anchoring points, the bridge is built entirely of Dyneema rope, a lightweight material that is capable of bearing very heavy loads, which makes it ideal for aerial construction.

"Spanning 7.4 metres (24.28 feet) between two scaffolding structures, the bridge consists of 9 rope segments for a total rope length of about 120 metres (3.93.7 feet) and is composed of different elements, such as knots, links, and braid."

A researcher tests the bridge. ETH Zurich

To build the bridge, the drones first measure the gap they need to span, communicating wirelessly with an offboard computer that runs the algorithms and translates them into commands, sending them back to the drones. This allows the drones to select the best anchor points for the rope, looping it around to create a secure knot. The computer also calculates where the bridge should be tied and braided.

To perform the task of bridge-building, the drones are fitted with a motorised spool of rope. This allows the drone to control the rope's tension as they unspool it, guided by a plastic tube to a release point between two of the propellers.

The drones were also custom-built for the task. As they work to build the bridge, the rope applies external forces and torque back to the drones, which needs to be calculated and corrected for. This ensures that the drones can maintain steady flight while building the bridge.

The final bridge, built in ETH Zurich's Flying Machine Arena, was then tested by the researchers, who walked across the bridge to ensure it could bear their weight.