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A multidisciplinary team from the NYU Tandon School of Engineering has received a $1.2 million grant from the National Science Foundation (NSF) to develop autonomous, mobile construction 3D printers. Down the line, the researchers hope that their work will untether 3D printers, so to speak, and enable them to build structures with more mobility.

When one thinks of the movement of a 3D printer, what comes to mind is extruder nozzles moving across the horizontal plane. On the more flexible side, one can also think of robotic arms equipped with print heads, which can move in a myriad of ways. Still, in both cases, the 3D printing process is still bound by an immobile box or gantry.

Within the industry, this hasn’t presented a significant challenge, but a team from NYU’s Tandon School of Engineering believe that exciting and new applications could be opened up for additive technologies if they were given more mobility.

The concept presented by the team consists of autonomous systems for 3D printers on robotic arms that are themselves attached to mobile, roving platforms. The mobile robotic 3D printers would be designed to work in teams—an approach called collective additive manufacturing (CAM). In the field, the 3D printers would rely on machine learning and AI to complete such tasks as bridge or tunnel repair, deep ocean work or disaster relief and rebuilding. The mobile 3D printer team could potentially even be used to construct buildings and structures on Mars.

Localization, control and coordination

According to the multidisciplinary research team, it will focus on a few main areas centered on autonomy, control, real-time systems and networking to ensure the autonomous, mobile 3D printing teams are viable. The key areas are:

Planning and localization: the 3D printers will have to situate and understand their placement in relation to the other 3D printers and to the 3D print at hand without GPS.

Model predictive control: the mobile base and manipulator will have to be efficient and stable enough to print quickly as well as to adapt to variations in real-world conditions at the printing site or variations in the printer’s functionality.

Printing and coordination: with multiple 3D printers working on the same project, it will be important to synchronize the motion of each machine using both the design of the part and the evolving structure of the print.

Working in Tandon

“The robot must be able to move quickly to the printing area, observe the real conditions — such as uneven ground, since the real world isn’t planar — then make compensations immediately,” explained Chen Feng, an assistant professor in Civil and Urban Engineering who is working on the CAM project’s planning and localization. “And while we want to have a higher degree of accuracy in the structure area, the further you are from structure the less you need. This will involve a new kind of proactive localization.”

Ludovic Righetti, an associate professor in Electrical and Computer Engineering, will put his expertise to use to develop the real-time optimal control algorithms for each mobile 3D printer, enabling each unit to respond and adapt rapidly to the environment. He said: ”Each robot has to observe what is being printed, autonomously associate it with the project design, and recognize instantly if the printed structure has deviated from it, and by how much, and all the while decide what are the next best actions to ensure proper printing of the structure.”

Maurizio Porfiri, a professor of Mechanical and Aerospace Engineer at NYU Tandon, will take the lead on developing a mathematical framework for the robots to autonomously coordinate their actions throughout the printing process. A high level of autonomy would make the system viable in such remote places as Mars, where a remote server would be ineffectual because of a time lag.

“Different from drones flying in formation or autonomous cars keeping distance from each other, our mobile printers leave a unique footprint in the physical environment: the object being printed,” he explained. “My work will leverage this very footprint to establish effective algorithms for coordination and collective printing.”

Finally, Weihua Jin, an industry professor in Civil and Urban Engineering, is helping the team to develop new composite materials for mobile construction 3D printing. The team hopes to showcase its work by 3D printing concrete structures at NYU Tandon.

Feng concluded: ”To unleash the full potential of collective additive manufacturing, several scientific boundaries must be pushed, ensuring optimal deployment of multiple mobile robots that print large structures according to an engineered, virtual design.”