Silk worms may no longer be alone in spinning a home from scratch. Researchers at MIT in the US have used swarms of robots that can spin tailored fibres in parallel to build architectural scale structures. The work simplifies use of fibre-glass, which can be awkward and expensive to work with, making it easier to exploit the potential anisotropy as well as the impressive mechanical, thermal, water absorption and termite resistant properties of fibre-reinforced composites that make them particularly useful in architecture. The researchers suggest that their swarms of autonomous spinning “fibrebots” that can produce fibre-reinforced composite structures will usher in “the next era of robotic architecture”.

Robot-spun versatility

The basic building components of the structures the fibrebots produce are tubes of fibre-glass thread and photocurable resin. However whereas previous use of robotics in architecture has essentially assembled pre-made components, the spinning robots can build from “a blank slate”.

Previous robotic winding systems that create tubes have had to compromise between tube length with curvature. To get around this trade off the MIT researchers designed robots that produce tubes in segments 90 mm in length and 100 mm in diameter. The robots spin each segment to overlap with the previous at the required angle for the desired curvature before curing, thereby maximizing the versatility of the spinning robots for a range of architectural designs.

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In addition, by programming multiple robots to operate in parallel, the structure designs can exploit the additional load-bearing support and constraint of co-woven tubes. To mitigate against communication challenges and the potential for collision the researchers invoked computations based on Reynold’s flocking algorithms. Artificial life and computer graphics expert Craig Reynolds developed a set of rules for simulating the simultaneous trajectory of multiple simple agents while avoiding collision, just as flocks of birds in flight.

“We augmented the traditional cohesion, separation, and alignment rules with additional user-specified interactions to create designs that allowed habitable spaces and goal-oriented structures, such as bridges, and avoided pre-existing obstacles,” the researchers explain in their report. “These additional rules were incorporated by weighted linear combinations of desired directions that were determined by repulsion or attraction points, which can be time-varying, or a bias among robots to curl around or follow alongside other tubes.”

The researchers demonstrated the potential of their spinning robot swarms in a 4m structure built by 22 of the devices in the space of 12 hours. The structure withstood the brunt of autumn and winter weather to augment the grounds of MIT in New England, USA, for seven months.

Markus Kayser and Levi Cai contributed equally to this work alongside corresponding author Neri Oxman and colleagues at the Mediated Matter Group at MIT, a group that conducts research at the intersection of computational design, digital fabrication, materials science and synthetic biology at scales ranging from the micrometre to full size buidings. They describe the work as “materials ecology”, and the result is a range of biologically inspired and engineered design fabrication tools and technologies and structures that aim to enhance the relation between natural and man-made environments.

Full details are available in Science Robotics Focus