Researchers use a swarm of drones for construction work and repairs

An international research team led by drone expert Mirko Kovac from Empa and Imperial College London has taken bees as a model to develop a swarm of cooperative drones. Under human control, the flying robots work as a team to print 3D materials for building or repairing structures, as the scientists report in the cover story of the latest issue of the science journal Nature.

3D printing is becoming increasingly important in the construction industry. Both on construction sites and in factories, stationary and mobile robots are already printing components in steel and concrete. A new approach to 3D printing uses flying robots: drones that employ collective construction methods – inspired by natural builders like bees and wasps.

As the research team led by Mirko Kovac, who heads the Materials and Technology Center of Robotics at Empa and is also a professor at the Imperial College London, reports in a cover story in the science journal Nature, the system called “Aerial Additive Manufacturing” (Aerial-AM) consists of a fleet of drones that work together for a single construction plan. These include so-called “BuilDrones,” which print and place materials in designated locations while in flight, and “ScanDrones.” They are used for quality control, continuously recording the performance of the “BuilDrones” and specifying the upcoming manufacturing steps.

The Aerial AM system is designed to allow the drones to adapt their activity to the different geometries of the structure during the construction process. They act autonomously during their flight mission, but there is a human “controller” who observes the process and makes adjustments as needed – based on the information provided by the drones.

To test the concept, the researchers developed four cement-like mixtures for the drones to build with. The test prints included a cylinder about two meters high made of 72 layers of a polyurethane-based foam and an 18-centimeter-high cylinder made of 28 layers of a specially developed cementitious material.

Throughout the build process, the drones evaluate the printed geometry in real time and adjust their behavior to ensure they maintain a manufacturing accuracy with a maximum deviation of five millimeters.

The tests conducted so far give the researchers confidence – even with a view to deployments in real-world construction.

“We’ve demonstrated that the drones can work autonomously to construct and repair buildings, at least in the lab,” says Mirko Kovac, “This scalable solution could facilitate construction and repair in hard-to-reach areas like high-rise buildings.”

The next step for the experts will be to work with construction companies to validate the developed solutions in the field and develop new repair and manufacturing capabilities. They anticipate that their technology will provide significant cost savings and reduced risks compared to traditional manual methods.