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Shelly Fan


Like a Swarm of Bees, These Drones Can 3D Print Structures While in Flight

Aerial-additive manufacturing creates a buzz

Published: Tuesday, October 25, 2022 - 11:02

I admit, if I see a beehive, I back away. But part of me is also fascinated. Beehives are a remarkable feat of engineering. Swarms of bees deposit materials ranging from tree buds to chewed-up wax into densely packed honeycombs—each a geometric masterpiece—while flying in the air.

In stark contrast, human construction is far more land-bound. Bulldozers, compactors, and concrete mixers are highly effective, and they’ve been the backbone for establishing our infrastructure. But they’re also bulky, unwieldy, and require roads or other means of transportation. This kneecaps their ability to rapidly respond to natural disasters on islands and other remote locations that need quick help, especially after emergencies.

Unfortunately, we’ve had increasingly frequent climate examples. Drastic road erosions due to raging wildfires. Highways and bridges that crumble after being soaked in water from floods and hurricanes. Recently, even as parts of Puerto Rico were still recovering from Hurricane Maria, many homes were once again flooded by Hurricane Fiona.

Is there a way to rapidly build shelters, or even houses, in difficult-to-access areas and better tackle these emergencies?

A team from Imperial College London took inspiration from bees and engineered a cohort of autonomous drones that 3D prints any designed structure. Similarly to bees, each drone acts independently but works with a team. The entire fleet is dubbed aerial-additive manufacturing (aerial-AM).

Some bees are builders—dubbed BuilDrones—that deposit material as they fly. Others are ScanDrones, acting as managers that continuously scan the current build and provide feedback.

In several tests, the fleet printed multiple structures—using materials from foam to a cement-like goo—to millimeter accuracy with minimal human supervision. It’s still a far cry from a finessed 3D-printed house, and more like a kid’s first attempt at pottery. Some structures resemble a rudimentary tower; others, a woven wicker basket.

We may be far from 3D printing bridges on the fly to evacuate people from an impending tropical storm. But the study shows a step toward that possibility. “Aerial-AM allows manufacturing in-flight and offers future possibilities for building in unbounded, at-height, or hard-to-access locations,” the authors write.

Robot construction

Using robots to help with construction is nothing new. But thanks to increasingly sophisticated algorithms, they’ve become handy tools in the infrastructure business. One idea is to help with tasks like finishing drywall, dramatically reducing the time required. Another is to battle the housing shortage plaguing us all. In the past few years, 3D-printed houses skyrocketed from fantasy to reality—from gorgeous tiny homes to affordable multiroom homes.

But what’s been lacking is rural access to the technology. Imagine pothole-filled dirt roads, bumpy on a sunny day and ankle-deep muddy after a torrent of rain. Picture wheels stuck in inches of mud, with no way to dig out other than a shovel. Now think about transporting massive 3D printers or other construction robots to that emergency site.

Not ideal, eh? Rather than battling earth and gravity, why not fly?

Weathering the storm

Inspired by bees, the team led by Mirko Kovac at Imperial College London took to the sky with ideas that weave together 3D printing and self-organizing drones that seamlessly build a “beehive” of a preprogrammed blueprint.

The main concept relies on our ability to shape certain materials at will—like squeezing Play-Doh or stacking Legos. This process lets us flexibly mold materials into different geometric designs—“free-from continuous additive manufacturing” (a mouthful, I know, so just “AM”).

It starts with an appreciation of free-flying builders in the wild. Take wasps: While not the friendliest of creatures, they’re remarkable in that they’re highly efficient in navigating their paths for dispensing building material. It’s like a flying carpenter building a cabinet seamlessly with a cohort—an incredible feat that scientists are still trying to understand.

Here, the team asked if it’s possible to achieve the same engineering prowess with a swarm of smaller robots. It’s a tough problem. Most previous approaches are only at an “early exploratory stage,” the team says, with “limited operational height.”

The solution was a software Aerial-AM framework that taps into previous engineering ideas and natural precedents so each drone can work in parallel as a swarm. Drones also had to act as faithful 3D printers while in flight, broadcasting their location and activity to their neighbors (so there’d be no extra “icing” on a structure). Each was then equipped to navigate the airspace without bumping into each other and with limited human interference. Finally, depending on the given structure, they carefully squeezed out a lightweight, foam-like material or a printable cement mix, based on instructions.

The brain behind the operation is Aerial-AM, which combines physics with AI to program two different types of aerial robot platforms. One is the BuilDrone, which autonomously deposits any material based on its programming. The other is ScanDrone, the quality-control bot that scans ongoing construction with computer vision. Like a manager on a construction site, ScanDrones give feedback to construction drones with every deposited layer.

The process isn’t completely run by robots. Human supervisors can tap into both the manufacturing strategy phase—that is, the best way to print a material—and the manufacturing phase. Before printing, the team ran a simulation to generate a “virtual print” using three or more drones.

For proof of concept, the team challenged their 3D-printing platform, Aerial-AM, with several shapes and materials. One was a cylinder more than 6.5 ft tall, printed with more than 72 layers of material made from polyurethane foam. Another type of BuilDrone was optimized for a cement-like mix and built a thin cylinder nearly 4 ft tall.

For a final test, six drones helped construct a parabolic surface (picture a thimble). Using those data, the study ran several simulations, asking how the scale of the structure and the number of robots changed the eventual build.

Overall, the construction swarm came off as highly adaptable, not just to scale and structure but also to robot population size. Even as their numbers increased, they optimized their paths to avoid collision, like cooks at a bustling restaurant during the dinner rush.

The drone squad isn’t yet ready for prime time. For now, it’s only been shown to construct small-scale structures. But the team is hopeful. The Aerial-AM framework can print different types of structures in a multirobot dance without congestion, demonstrating “adaptation and individual robot redundancy,” the team said.

Although just the first steps, the work solidifies the feasibility of drones as aerial construction workers—those that could one day save lives by flying into dangerous territories. “We believe our fleet of drones could help reduce the costs and risks of construction in the future, compared to traditional manual methods,” says Kovac.

First published Sept. 27, 2022, on Singularity Hub.


About The Author

Shelly Fan’s picture

Shelly Fan

Shelly Xuelai Fan is a neuroscientist-turned-science writer. She completed her Ph.D. in neuroscience at the University of British Columbia, where she developed novel treatments for neurodegeneration. While studying biological brains, she became fascinated with AI and all things biotech. Following graduation, she moved to UCSF to study blood-based factors that rejuvenate aged brains. She is the co-founder of Vantastic Media, a media venture that explores science stories through text and video, runs an award-winning blog NeuroFantastic.com, and is the author of the book Will AI Replace Us? (Thames & Hudson, 2019).