A new method of 3D-printing allows robots to work cooperatively on concrete structures. The development could lead to on-demand designs at construction sites, and the building of structures in places humans cannot go. Our correspondent Miro Lu visits the lab in Singapore behind this discovery.

3D printing of large concrete objects currently requires printers bigger than the printed structures themselves, which is not feasible.

Scientists from the Nanyang Technological University of Singapore have developed a technology where two robots can work in unison to 3D-print a concrete structure.

This method of concurrent 3D-printing, known as swarm printing, paves the way for a team of mobile robots to print event bigger structures in future.

But to have multiple robots work together in a cooperative "swarm" is no mean feat. It requires seamless coordination and communication between the printers, which proved to be a challenge for the engineers.

LI MINGYANG, RESEARCH FELLOW SINGAPORE CENTER FOR 3D PRINTING "The most difficult part about this project is to get the exact position of these robotic arms. Once they know each other's positions, they can avoid collision with each other in order to print the same structure, they need to have very high accuracy. We use multiple sensors to get the positions, and on the mobile platforms we use distance sensors to calculate the distance they travel."

These robotic printing arms sit on top of mobile platforms and work in unison to print objects using materials like concrete, plastic, or clay, among others. According to the head researcher for this project, there are a lot of uses for this technology, especially in hard-to-reach or dangerous zones.

LI MINGYANG, RESEARCH FELLOW SINGAPORE CENTER FOR 3D PRINTING "It can perform construction works which humans cannot, especially dangerous space and outer space. For example on the moon or on Mars, we can send the robotic arms first to build the habitat for the astronauts first, before we send the humans there."

MIRO LU SINGAPORE "There are limits to swarm printing. At the current stage, the robots can only operate on relatively flat surfaces. Going forward, the team is working towards advancing the technology to allow more robotic arms to work in concert in order to build bigger projects. Miro Lu, CGTN, Singapore."