Robots build a wooden pergola

Students at the Swiss Federal Institute of Technology in Zurich (ETH) have been able to demonstrate the potential that digital fabrication holds for wooden buildings through their new project. They have built a wooden pergola on a terrace at the Istituto Svizzero in Rome. The elements of this four-metre-tall construction are joined with nothing more than wooden dowels. Apart from the joints between the metal floorplates and the supports, the pavilion makes absolutely no use of glue, screws or nails, the ETH reported in a press release.

The students designed the construction by means of a computer model. “It would have been impossible to use traditional methods to define the positions of the 700 wooden elements and 2,700 beech dowels in such a way as to produce a dynamic and harmonious whole,” explained Programme Director Hannes Mayer. “To do that takes rules, which, when translated into algorithms, unite all the disparate elements into a powerful and graceful structure.”

All the elements making up the pergola were manufactured in the Robotic Fabrication Laboratory at ETH in Zurich. Two robot arms fitted to a gantry system suspended from the ceiling took their instructions from the digital model to build the structure. While one arm held the wooden slats in place with millimetre precision, the other drilled holes for the wooden dowels at various opposing angles. “Robots are the perfect tool for this job, because they can position the individual elements with incredible precision. This allows us to bring the most complex and nuanced of digital designs into reality,” said Hannes Mayer.

However, a little human involvement was still required, as the students had to hammer all the wooden dowels into place by hand. They first dried the dowels in an oven to shrink the wood and then moistened them once they were in place to make them swell up and create a solid join. “This is a case of wood and moisture interacting with the digital design and fabrication tools to push the boundary of what wood joining techniques can do,” commented Mayer.

ETH reported that the pavilion was designed, developed and built in under ten weeks.