A fleet of "bee-inspired" 3D drones that build and repair structures while flying has been created by a team of researchers.

Researchers from Imperial College London and Empa, the Swiss Federal Laboratories of Materials Science and Technology, have developed the technology which has been tested in the lab and could ultimately be used for manufacturing and building in difficult-to-access or dangerous locations, such as tall buildings, or to help with post-disaster relief construction.

The new approach to 3D printing uses flying drones that use collective building methods inspired by natural builders like bees and wasps who work together to create large, intricate structures.

The drones in the fleet, known collectively as Aerial Additive Manufacturing (Aerial-AM), work co-operatively from a single blueprint, adapting their techniques as they go. They are fully autonomous while flying but are monitored by a human controller who checks progress and intervenes if necessary, based on the information provided by the drones.

Lead author Mirko Kovac, of Imperial’s Department of Aeronautics and Empa’s Materials and Technology Centre of Robotics, said: “We’ve proved that drones can work autonomously and in tandem to construct and repair buildings, at least in the lab. Our solution is scalable and could help us to construct and repair building in difficult-to-reach areas in the future.”

It comes as 3D printing is gaining momentum in the construction industry. Both on-site and in the factory, static and mobile robots print materials for use in construction projects, such as steel and concrete structures. Bam Nuttall head of innovation Colin Evison has previously told The Engineers' Collective podcast about the opportunities provided by the method, which has also been trialled on HS2 and on the M8 bridge in Glasgow.

In this case, Aerial-AM uses both a 3D printing and path-planning framework to help the drones adapt to variations in geometry of the structure as a build progresses. The fleet consists of BuilDrones, which deposit materials during flight, and quality-controlling ScanDrones that continually measure the BuilDrones’ output and inform their next manufacturing steps.

To test the concept, the researchers developed four bespoke cementitious mixtures for the drones to build with. Throughout the build, the drones assessed the printed geometry in real time and adapted their behaviour to ensure they met the build specifications, with manufacturing accuracy of five millimetres.

The proof-of-concept prints included a 2.05m-high cylinder (72 layers) with a polyurethane-based foam material, and an 18cm-high cylinder (28 layers) with a custom-designed structural cementitious material.

The technology offers future possibilities for building and repairing structures in tall or other hard-to-access locations. Next, the researchers will work with construction companies to validate the solutions and provide repair and manufacturing capabilities.

Kovac said: “We believe our fleet of drones could help reduce the costs and risks of construction in the future, compared to traditional manual methods.”

The work was funded by the Engineering and Physical Sciences Research Council (part of UKRI), the Royal Society, the European Commission’s Horizon 2020 Programme, Royal Thai Government Scholarship and a University of Bath Research Scholarship. The project is also supported by Industrial Partners Skanska, Ultimaker, Buro Happold, and BRE.

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