Future of Making Series: What Lies Beneath the Sequential Roof
24 August 2017
The world’s largest
robotically constructed roof is an impressive
feat—but not more so than the robotic
architecture experiments that will
happen under it.
When the Institute for Technology in Architecture (ITA) needed a new
home at the engineering and science university ETH Zurich, the institute
approached the challenge as it does most of the work done there: as a
life-size research project. Here, the ITA could explore concepts
including zero-emissions architecture, the digitization of the
construction process, robotic construction, and the creation of a
building free of central supporting structures. It would be research
done at a scale of 1:1.
The result is the Arch_Tec_Lab, which opened in September 2016. The new
building is an impressive feat of architecture
and a real-life application of ITA research. Beneath the zero-emission
structure’s curved wood roof is a workspace—the Robotic Fabrication
Laboratory, big enough for four industrial robots to build a two-story
building, where the ITA’s groundbreaking research continues.
The roof itself is the biggest proof point: It was designed
computationally and built by robots, signaling a new generation of
construction and a new world of man-machine interaction. The Sequential
Roof, as the undulating structure is known, was built by robots working
“essentially like a massive
3D printer. It’s layer on layer on layer of
timber,” says Russell Loveridge, the managing director of research at
Switzerland’s National Centre of Competence in Research (NCCR) Digital
Fabrication, a research group housed at ETH Zurich that now resides in
the new building. The nationally funded research program is a rigorous
multidisciplinary investigation into advanced fabrication, smart
materials, and experimental construction techniques.
Also under the new roof, and embedded in the framework of the NCCR, is
the research program of professors Fabio Gramazio and Matthias Kohler,
NCCR principal investigators. Their research into robotic fabrication
helped lead to this innovative roof; their program’s past projects (see
page 184) indicate the kind of work that the new building’s Robotic
Fabrication Laboratory will host.
Left: This 2015 project, Smart Dynamic Casting, investigated robotic
fabrication of complex concrete structures and particularly the need (or
lack) for individual frameworks for the structure. Right: For a 2011
project, The Endless Wall, a robot had to z its own position, its
surroundings, and the tolerances of the bricks at Hand. The system had
to respond to changing conditions as it built and rebuilt the “endless
wall.”
The Sequential Roof is the largest robotically built timber structure in
existence. It is essentially a massive timber structure covered in a
rubberized polymer membrane, which eliminated the need for interior
finishing—there are no drywall or acoustic panels in sight. Rather than
a building-wide HVAC system, small heating and cooling units are
distributed throughout the building with sensors to fine-tune the
climate control. Spaces were left in the roof trusses for installing
lights, skylights, ventilation, and wiring, and the roof itself is an
acoustical diffuser, creating a quiet space underneath the roof for
people to work.
“The choice of materials and the amount of materials you use is by far
the biggest input in the ecological costs of construction,” Loveridge
says. “If we can design something like the roof to serve all these
functions and eliminate those other materials, we know that we’re
building more sustainably than if we do it more cheaply.”
A robot-based assembly process created the woven trusses, demonstrating
the potential of combining digital fabrication techniques with timber.
The zero-emission build started from the ground up: The structure was
constructed on top of an existing parking garage, avoiding the energy
and environmental effects of a new foundation. The first level of the
building houses the Robotic Fabrication Library, which Loveridge
describes as an engineering testing hall. Above the testing hall are the
offices for NCCR, and above that is an open space under the roof where
researchers can work and collaborate.
The testing hall is where the roof was fabricated. During the build,
four industrial robots hung from the ceiling of a 60 x 14 x 8 meter
space. The robots worked on gantries with six degrees of freedom, all
controlled by the same system so they could work in sync. “There’s never
been a case where four synchronous robots can do things together,”
Loveridge says. Each robot was capable of holding up to 30 kilograms (66
pounds), so one could hold an object while the other three worked on it
with various tools.
A ceiling-mounted gantry allows for large-scale implementation of robotic fabrication projects by means of four cooperating industrial robots.
Building the structure took a village. ETH Zurich faculty asked ERNE AG
Holzbau to realize a parametric roof design for the ITA and employed the
robotics manufacturing company Guedal AG, which had created a small
robotic woodworking system. Zurich-based ROB Technologies was tapped to
provide control and operation software.
The Sequential Roof is made up of 48,624 individual timber slats,
assembled into 168 roof trusses and truss girders that are interwoven
into a 2,308-square-meter (24,843-square-foot) free-form roof.
Fabricating the complex roof geometry was dependent on an integrated
digital planning process that mixed together elements of structural
analysis, design, and fabrication data generation.
Architects at the institute built a 3D model of the Sequential Roof,
which they sent to structural engineering consultants who used a nail
image generator to place each of the 800,000 nails necessary in the
model. (Nails were a better choice than glue for the roof, but also
involved intense calculations related to the material and the complex
geometry of the roof.) Then ERNE checked the data and prepped it for
robotic machining.
During production, the gantry robot also functioned as a quality
analyst. A photogrammetric system compared each node and nail image with
the target plan, creating a QA feedback loop that ensured everything was
being built correctly. After the system checked all the nails, the
trusses were brought to the site.
Despite the success of this project, Loveridge doesn’t believe that
robots will ever entirely replace construction workers. Instead, the
backbreaking work of construction will evolve into a job that has a
symbiotic relationship with the machines, and it will no longer be a
young man’s realm. Computational analysis has improved in the past
decade to give machines enhanced spatial awareness and precision. But
you still need someone to make sure the computers are making the right
decisions and completing tasks in the correct order. Even now, you see
workers becoming more intellectually engaged in construction and less
physically engaged, and that will accelerate with the rise of robotic
fabrication.
“A lot of the jobs being done in the construction industry rely on the
human’s ability to look, process, and judge things, and rely on
experience, and then do the physical work in reaction to that,”
Loveridge adds. “There’s an inherent tacit knowledge that comes from
working on a construction site that is not programmable. The way things
come together is never perfect, no matter how much you do. There’s
always going to be a need to have people who know how things go
together.”
Part 3 of a 5-week series from the new Future of Making book by Tom Wujek. Stories will be posted here on In The Fold and on Redshift. To learn more about the book, visit www.autodesk.com/future-of-making-book
--ENDS--
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