Their name was inspired by the sound made by bees – and now there is a challenge to make drones actually work like bees do.

Researchers at two learning institutions in the UK have made history by creating the first ever fleet of drones to build structures at high altitude using 3D-printing technology.

The flying drones, which employ co-ordinated building methods inspired by natural builders like bees and wasps, 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 researchers say.

“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,” a statement from Bath University read.

“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.”

The researchers say that the discovery of in-flight 3D printing unlocks doors that will lead to on-site manufacturing and building at difficult-to-access or dangerous locations like tall buildings.

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.

Funded by the Engineering and Physical Sciences Research Council, part of UKRI, the project was launched after a pilot research collaboration and award for a demonstration on pipeline repair.

It was led by Imperial College London and involved researchers at Bath.

Lead investigator Professor Mirko Kovac, of Imperial’s Department of Aeronautics, 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.”

Dr Wenbin Li (Department of Computer Science), who started working on the project whilst at Imperial College London before switching to Bath, worked on developing autonomy of the drones so they could carry the materials and control their movements precisely to accurately 3D print the objects.

Dr Richard Ball and Dr Paul Shepherd – both investigators at Bath – along with researchers Dr Barrie Dams, Dr Chris Williams and Dr Shamsiah Awang Ngah, from the Department of Architecture & Civil Engineering, worked on the cement-like materials used by the drones to repair or build structures.

“We have developed new cutting-edge materials which are optimised for the unique properties required for aerial additive manufacturing, such as being low-viscosity, light-weight and quick-setting,” Dr Ball said.

The research has been detailed in the paper Aerial Additive Manufacturing with Multiple Autonomous Robots, which features in the latest edition of Nature.

Aerial-AM uses both a 3D printing and path-planning framework so the drones can 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 tested four cement-like mixtures for the drones to build with.

Throughout the process, 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. An important aspect of this is to accurately predict the performance of the printed structure to ensure mechanical integrity through the printing process.

The proof-of-concept prints included a 2.05-metre high (72 layers) cylinder with a polyurethane-based foam material, and an 18-centimetre (28 layers) high cylinder with a custom designed structural cement–like material.

It was not made immediately clear how long the drones could last in the air on a single battery charge, although the researchers the drones are made with very light material to conserve energy.

“Our next step is to work with construction companies to validate our solutions and provide repair and construction capabilities,” Dr Shepherd said.

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