By Adam Jiu | MIT News
Robotically assembled building blocks may be a more environmentally friendly method for erecting large-scale structures than some existing construction techniques, according to a new study by MIT researchers.
The team conducted a feasibility study to evaluate the efficiency of constructing a simple building using “voxels,” which are modular 3D subunits that assemble into complex, durable structures.
After studying the performance of multiple voxels, the researchers developed three new designs intended to streamline building construction. They developed a robotic assembler and a user-friendly interface to create voxel-based building layouts and feed instructions to the robot.
Their results indicate that this voxel-based robotic assembly system can reduce embodied carbon — all carbon emitted during the life cycle of a building material — by as much as 82 percent compared to popular techniques such as 3D concrete printing, precast modular concrete and steel framing. The system will be competitive in terms of cost and construction time. However, the choice of materials used to make voxels plays a major role in their carbon footprint and cost.
Although important considerations such as scalability, durability, long-term robustness, and fire resistance remain to be explored before such a system can be widely deployed, the researchers say these preliminary results highlight the potential of this approach for automated, on-site construction.
“I am particularly excited about how robotic assembly of discrete lattices can enable a practical way to apply digital fabrication to the built environment,” said Mianna Smith, a graduate student at MIT’s Center for Bits and Atoms (CBA).
He is joined on the paper by Paul Richard, a graduate student at École Polytechnique Fédérale de Lausanne in Switzerland and former visiting researcher at MIT; Alfonso Parra Rubio, a CBA graduate student; and senior author Neil Gershenfeld, an MIT professor and director of CBA. Research appears in Automation in construction.
Designing better building blocks
For the past several years, researchers at the Center for Bits and Atoms have been creating voxels, which are lattice-structured building blocks that can be assembled. Materials with high strength and stiffnesssuch as airplane wings, wind turbine blades and aerospace structures.
“Here, we’re taking the principles of space and applying them to buildings. Why don’t we build buildings as efficiently as we build airplanes?” Gershenfeld said his lab has done voxel assemblies with NASA, Airbus and Boeing based on previous work.
To explore the feasibility of voxel-based assembly techniques for buildings, the researchers first evaluated the mechanical performance and durability of an existing eight-voxel design, including a cuboctahedron made from glass-reinforced nylon and a Kelvin lattice made from steel.
Based on this evaluation, they created a set of three voxels using a new geometry that could be more easily assembled robotically into a larger structure. The new design, based on a high-strength and high-stiffness octet lattice, self-aligns into a mechanically stiff structure.
“The interlocking nature of these voxels means we can get excellent mechanical properties without having too many connectors in the system, so the construction process can go much faster,” Smith said.
To speed up the construction, they are a design Robotic assembly systems Based on inchworm-like robots that Crawl across a voxel structure Anchors and extends their body. These modular inchworm lattice assembler robots, or MILAbots, use grippers at each end to place voxel building blocks and engage snap-fit connections.
“Robots can assemble voxels by dropping them into place and then stepping on them to interlock the pieces. We can do precise maneuvers based on the mechanical relationship between the robot and the voxels,” explains Smith.
The team studied the embodied carbon required to create their new voxel design using three materials: plastic, plywood and steel. They then evaluated the throughput and cost of using a robotic assembly system to build a simple, one-story building. The researchers compared this estimate with the performance of other construction methods.
Potential environmental benefits
They found that most existing voxels, and especially those made from plastic, performed poorly compared to existing methods in terms of sustainability, but the steel and wood voxels they designed offered significant environmental benefits.
For example, using their steel voxels would generate only 36 percent of the embodied carbon required for 3D concrete printing and 52 percent of the embodied carbon of precast concrete. Plywood voxels had the lowest carbon footprint, requiring about 17 percent and 24 percent of embodied carbon, respectively.
“There’s still a potentially viable alternative to the plastic-based voxel approach, we just have to be more strategic about what kind of plastic, infill and geometry we use,” Smith said.
Additionally, the projected on-site assembly time for the steel and wood voxel method averaged 99 hours, compared to an average of 155 hours for the existing construction method.
These speed advantages depend on the distributed nature of voxel-based assembly. Although a MILAbot working alone is much slower than existing techniques, with a team of 20 robots working in parallel, the system can catch up or surpass existing automation methods at low cost.
“One advantage of this approach is how scalable it is. You can start building, and if it turns out you need a new room, you can just add to the structure. It’s also reversible, so if your usage changes, you can isolate the voxels and change the structure,” Gershenfeld said.
The researchers also developed an interface that enables users to input or hand-design a voxelized structure. The automated system determines the paths MILAbots should follow and sends commands to the assemblers.
The next step for the project will be a larger testbed in Bhutan, using the “super fab lab” that CBA helped build to replicate the robots there to test the construction of a planned sustainable city, Gershenfeld said.
Additional areas of future work include studying the stability of voxel structures under lateral loads, improving design tools for system physics, improving MILAbots, and evaluating voxels containing sheeting, insulation, or electrical and plumbing routing.
“Our work supports why this type of distributed robot assembly could be a practical way to bring digital fabrication to building construction,” Smith said.
“It’s a visionary example from Neil Gershenfeld and his team, finding ways to make buildings themselves with tiny robotic machines. I’m now fascinated by how we can use an idea like this to make the exteriors of buildings more attractive and pleasing, making it more affordable,” said Thomas Heatherwick of Studio and Design Firm, who found designer Heatherwick. was not involved in this study.
This work was funded, in part, by the MIT Center for Beats and Atoms Consortium.
–
Reprinted with permission MIT News
Image: splash
–
If you believe in the work we’re doing at The Good Men Project, please join us as a Premium Member today.
All premium members can watch The Good Men Project without any ads.
Need more information? A full list of benefits is here.
