Drones already fly and spy. Now, they can build too. For the first time, free-flying robots have 3-D printed structures. A pair of drones working together made a tower taller than a person. Engineers demonstrated this new method of 3-D printing in the lab. They shared their success in Nature on September 22.
Mirko Kovac, who co-led the research, says that animal builders inspired him. “Wasps are amazing,” he says. “Bees are incredible.” These insects work together in swarms to make nests much larger than themselves.
Kovac is a roboticist at Imperial College London in England. He also works at Swiss Federal Laboratories for Materials Science and Technology (Empa) in Dübendorf. His co-leader on this project was architect Robert Stuart-Smith of the University of Pennsylvania in Philadelphia and University College London in England.
Spraying foam and squirting cement
To print that person-sized tower, a Build-Drone carried expanding foam. This material rapidly expands and hardens when sprayed. As the drone flew in a slow circle, it sprayed the foam downwards to form layers. When it ran out of material, it flew away so a person could reload more foam or replace the drone’s batteries.
This type of foam tends to thicken unevenly. So, while Build-Drone was reloading, a second, smaller drone surveyed the work. It was called Scan-Drone. It looked for places where the last layer was too thin or thick. Then it created a plan for the next layer to help even things out. This kept the tower straight and sturdy.
The foam tower was cool, but the team wasn’t done. In a second demo, Build-Drones and Scan-Drones worked together to make a cylinder about the size and shape of a large round cake. This structure was impressive because the drones laid down a cement-like material very accurately, to within millimeters.
The cement-like material was special, too. Researchers at the University of Bath in England crafted it specially for…
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