Robotics in Construction: Experiments in Onsite Fabrication and Prefabrication

NCCRs, or National Centers of Competence in Research, are a research funding initiative of the Swiss government conducted by the Swiss National Science Foundation.

Each center is hosted and supported by a Swiss academic institution and focuses on a thematically-limited area of research, with a network of partners in the academic sphere and beyond. These cross-disciplinary research networks focus on high-risk, high-return research of strategic importance for the future of the Swiss economy.

Russell Loveridge is the Managing Director for one such institution, NCCR Digital Fabrication. Initiated in 2014 and based out of ETH Zurich, NCCR Digital Fabrication is comprised of 150 researchers and 28 professors from different areas of expertise, including architecture, structural design, materials science, computer science, robotics in construction, and control systems engineering. NCCR Digital Fabrication aims to lead the development and integration of digital technologies within architecture and future building processes.

With a 12-year mandate and research funding, NCCR Digital Fabrication has a framework to test out ideas and execute long-term projects that commercial firms often can’t afford. Their research centers around two major challenges: on-site digital fabrication, bringing new technology onto construction sites, and bespoke digital prefabrication, by using the safe environment of the lab to test new ideas for robotics in construction.

Robotics in Construction & Onsite Digital Fabrication

_{NCCR Digital Fabrication has a framework to test ideas and execute long-term projects that commercial firms often can’t afford}

NCCR Digital Fabrication’s On-Site Digital Fabrication projects aim to bring digital fabrication onto building sites. Researchers investigate integrated design, planning and robotic control methods, develop versatile on-site fabrication robots, and examine cooperation models for man-machine and machine-machine interactions. According to Loveridge, the guiding question for these projects is “What can we do to get these technologies out there to give us capabilities we don’t have?”

The first question the team decided to tackle was “how can we build in concrete without any formwork?” To solve this problem, they first developed an in-situ fabricator, an on-site robotics system. Like others bringing robots that can move on the construction site, the team faced the challenges of localization and precision. According to Loveridge, the biggest thing they learned was “the only thing that matters for robots on the construction site is where the tool is. You don’t have to worry about where the robot is or the platform is. As long as we know where the tool is, all the reverse schematics can be calculated.”

Mesh Mould

The end result of bringing the in-situ fabricator to concrete is a project known as Mesh Mould, a waste-free robotic fabrication process for fully load-bearing, non-standard concrete constructions. Mesh Mould allows walls and columns to be made without any formwork, by using a computer-generated digital model in conjunction with robots to fabricate a high-precision steel mesh dense enough to retain fluid concrete. While Mesh Mould can be used to build standard concrete walls, it is especially beneficial for curved and non-standard shapes. Mesh Mould project seeks to make non-standard reinforce concrete architecture sustainable and economically feasible by eliminating the need for expensive custom formwork.

In 2016, Mesh Mould won the Swiss Technology Award, a first for a construction technology. Since winning the award, the team has upscaled Mesh Mould to be able to build on-site and constructed the first Mesh Mould walls on-site in real-world conditions. Made with 6mm rebar, the project used normal concrete with some additives to increase its viscosity, allowing it to be pared during its plastic phase and creating a coating for the rebar. The Mesh Mould process can eliminate the need for formwork on any kind of geometrically curved walls that a robot can possibly build.

Bespoke Digital Fabrication

_{The guiding question for NCCRDF is “What can we do to get these technologies out there to give us capabilities we don’t have?”}

The NCCR Digital Fabrication team is also at-work on pushing forward the possibilities of prefabrication. According to their stated research goals, “Bespoke Digital Prefabrication augments the advantages of manufacturing through the use of digital building technologies. It enables custom-designed, large-scale digital prefabrication of complex architectural elements. Researchers work at the 1:1 building scale, developing resource-efficient material systems, joining methods, design tools and computational technologies.”

NCCR researchers developed a new digital timber construction method that expands the range of possibilities for traditional timber frame construction by enabling the efficient construction and assembly of geometrically complex timber modules. Since robotics aren’t constrained by angles that are easy for people to cut, the framing can be cut at any angle, minimizing the amount of timber and opening new possibilities. Unlike traditional timber frame construction, Spatial Timber Assemblies can manage without reinforcement plates because the required rigidity and load-bearing result from the geometric structure.

The way it works is one robot guides a timber beam as it is sawed to size, while a second then drills the holes for connecting the beams. The two robots then work together to position the beams as arranged in the digital model. To prevent collisions when positioning the individual timber beams, the researchers have developed an algorithm that constantly recalculates the path of motion for the robots. Finally, workers manually bolt the beams together.

With these tests and technologies, NCCR Digital Fabrication is pushing the boundaries of what is possible with robotics in construction.

About this series: In June 2018, Autodesk and MassRobotics (a Boston-based nonprofit innovation hub focused on needs of the robotics community) held the Robotics in Construction Summit at the Autodesk BUILD Space in Boston. We've documented the information and discussions from the summit and packaged them into a Robotics in Construction eBook.