Quadcopters with 3D Printing abilities were inspired after Swiftlets. via New Scientists

“BEWARE: WILD ROBOTS AHEAD” reads the sign on the cage. Inside, a hexacopter – a drone with six rotors – hovers menacingly. A quadcopter – with four – rests on the ground.

They aren’t really wild robots, of course, and the test arena isn’t much of an ecosystem, but the quadcopter in particular has a rather special skill: it can build its own nest out of foam. In effect, it’s the world’s first flying 3D printer. One day such drones might work together to help remove waste from nuclear sites or help patch up damaged buildings.

Inspired by the swiflets that build nests using their own saliva, Mirko Kovac of Imperial College London and his team wanted an aerial robot that could make structures. The quadcopter carries two chemicals which create polyurethane foam when mixed, and a printing module to extrude the foam. As we watch, it takes off and hovers over a box in the arena, before lowering an arm and squirting the foam on to the box.

All of this has been done more or less autonomously; after the box’s coordinates are programmed in, the quadcopter uses GPS to direct itself to the target. The quadcopter’s job done, the hexacopter now lands on the foam and, after a few minutes’ wait while the foam sets hard, it takes off again, carrying the box with it. The idea is that if the box contained, say, radioactive waste, this would be a safe way to remove it. The team has also developed versions of the drone that carry hacked Kinect cameras to survey the environment and work out where to land.

The hexacopter can carry 2.5 kilograms, but scaled-up versions could carry up to 40 kg, says Kovac. It runs on a regular battery but he envisages a fuel cell that the robots could recharge by resting on a treetop and deploying solar panels. “They will build nests to recharge their batteries with solar cells and to observe the environment,” he says. Other possible uses include patching up damaged roofs and building bridges.

The aim is to increase the range of drone missions, says Thomas Creedy, an ecologist at the Natural History Museum in London who is working with Kovac. “In particular, extending the scope of scientific survey robots in challenging environments such as rainforests through the adaptable construction of recharging platforms or monitoring stations.”

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