In November 2016, then technology start-up company Cazza Construction Technologies of California came onto the scene with the dream of building 3D-printed smart cities all over the world. In June 2017, their patented 3D printing construction robots, known as the X1 and the X1 Core, were launched. They combine large-scale 3D printing with traditional building methods, making construction more efficient, eco-friendly and cost-effective. However, large-scale, albeit 3D-printable, structures like buildings can be held back by volume and time constraints, whereas robot arms can be used to print anywhere within their reach.

In August 2018, a team of roboticists from the “Nanyang Technological University” of Singapore (NTU Singapore) published their work “Large-scale 3D Printing by a Team of Mobile Robots” in the “Automation In Construction” journal. It speaks of how the researchers were able to use two simultaneously operating robot arms on mobile bases, to 3D print a structure made from a single piece of concrete. The team’s mobile robot system can define its own build volume, ergo it can hypothetically build structures that infinite in size.

As of August 2018, the system is still an early proof of concept. While the two robots 3D printed a structure together, their bases don’t yet move around by themselves during printing. An array of cameras guides the robots during printing, although the current system is not designed to be used outdoors.

It took the researchers several years to get to where they were in August 2018; their efforts to refine the concept is ongoing. The team are also working on adding on-board obstacle and human detection to improve the autonomy of the robots, in addition to modifying the robot arms to use scissor lifts to extend their reach.