If you want to see the perfect building, don’t look to the nearest skyscraper. Look to the nearest tree.
I was skeptical, too, until Steven Keating, of MIT’s Mediated Matter Group, convinced me with a rapid-fire list of facts. A tree builds itself on site. Its materials don’t come from a factory, but mostly from the air. Its structure–from the branches to the leaves–respond to its unique need for light in the context of its particular plot in the forest. And its trunk is a testament to the efficient use of materials. It usually tapers as it reaches the sky. And while the naked eye can’t tell, its core is less dense than its outer rings, because the core isn’t necessary for support.
Keating’s Digital Construction Platform (DCP) looks nothing like a tree. It’s a four-ton solar powered robot arm on tank tracks. And yet, it’s a working proof-of-concept that a machine can build a lot like a tree does, sourcing local energy and adapting to local conditions to construct a building out of local materials–anything ranging from dirt, to ice, to moon dust.
Put more simply, DCP is like a Wall-E that builds things, rather than cleaning up trash.
Though the project has been in the works since 2011, the DCP team recently unveiled a massive update to their robotic platform. It’s one part practical construction bot, one part heady architecture project.
Most existing building-scale 3D printers look a lot like big conventional printers. They involve huge gantry cranes that tower over structures, extruding one layer of cement at a time like they’re piping icing on a giant cake. For all sorts of reasons, these systems lack scalability. They’re unwieldy, the equipment itself is foreign to construction crews, the material can often only be laid from one angle (making it almost useless for arches), and the cement is often very different than what would be used on most job sites. That’s all in addition to perhaps the biggest deal breaker of them all. Layering concrete, rather than pouring it, results in weaker, less predictable structures. In short, 3D-printed concrete tends to be less strong.
DCP is different. For one, it’s based upon an Altec aerial-lift system–that’s the same sort of bucket truck you might see suspending a worker at a construction site–so it’s contractor-friendly. However, the bucket has been swapped out for a major upgrade: A Kuka robot arm typically used on assembly lines, which has been loaded with extra sensors to measure all kinds of site metrics, from topography to radiation. The tip of the arm is fit with a nozzle that can mix and spray mud, foam, or concrete–basically any viscous building material you could imagine. That nozzle can also be equipped with a grinder or welder, as needed.
Fitted with tracks and solar panels, the system can be deployed almost anywhere and takes just minutes to set up. It can operate for eight hours on one charge. But even with diesel backup motors, and an excavator to help collect dirt for compression into bricks, or sand for sintering into a sprayable material, the DCP can fold up small enough to drive through a set of standard double doors.
It’s a huge amount of engineering, packed into what looks like a homemade amalgam of hodgepodge parts. But early tests with the DCP are impressive.
In its most notable practical achievement to date, it constructed a 50-foot-wide dome from the inside, all out of a stock-insulating foam spray. The process took a mere 13.5 hours. Of course, it isn’t a totally completed building. It’s just foam, after all. But it features that same efficient, tapering design of the aforementioned tree. And it can serve as a mold within which concrete is poured–a common construction technique known as insulated concrete formwork, which is used frequently in building foundations.
“This one technique allows us to get our foot in the door on a construction site,” says Keating. And the system’s robust digital back end could keep it there. A robotic construction worker would have perfectly predictable build times, and with enough time and experience, such a system could convert blueprints into quantifiable costs without the guesswork of contractors, who must often wait for one another to complete jobs like HVAC or wiring before they can go to work.
“When you look at a construction site, how often do you see all the machines moving all the time?” asks Keating. “They’re usually standing still.”
Truth be told, Keating sounds a bit bored at the prospect of DCP becoming the next Caterpillar and developing the newest wave of smarter building bots. The lab isn’t writing off corporate opportunities, but it did put all of its hardware specs and digital software online, open, for anyone to take and use. Instead, it seems that DCP’s future resides closer to that perfect building–the tree.
The team is focused on the next development of the platform, especially how it could take advantage of onsite building materials, rather than foams and concretes born from factories. One stop could be Antarctica, where the DCP could be used to craft structures out of ice, with big bricks formed, cut, and assembled like Lego. “We’ve shown how we could do [it],” says Keating. “And NASA is very excited to use ice for printing on Mars because ice absorbs a lot of cosmic radiation.” Similarly, more experiments with sand and soil could equip DCP for work on the moon.
The even longer view? Load up the DCP with organic building materials, like animal proteins and photosynthetic E. coli, to print living buildings. In fact, the Mediated Matter Group has already synthesized living plastics from squid and cuttlefish--materials that might one day be programmed to change color in the presence of CO2, or self-repair cracks rather than requiring a contractor to fix them. It’s easy to imagine these buildings adapting to their environments and growing to nurture themselves and their cohabitants, just like trees do. As Keating put it to me, “We would love to see the project be used in industry. But for us, we’re much more excited in the research front.”