Robots are gaining traction when it comes to the highly precise construction of geometrically complex assemblies. Initially, architects employed them to fabricate small-scale, prototypical installations. But as the technology continues to develop, architects are using machines to create larger, permanent structures.

In April, the University of Stuttgart’s Institute for Computational Design completed the construction of the Landesgartenschau Exhibition Hall, a 1,345-square-foot, 20-foot-tall pavilion created for the purpose of demonstrating innovative building methods. Its prefabricated lightweight timber shell, which has a surface area of 2,640 square feet, is the first structure to be made entirely of robot-fabricated plates, according to the project team.

The researchers selected beech plywood for its lightness, strength, local availability, and alignment with resource-sensitive forestry practices in Central Europe. After studying the microscopic plate joints in sand dollars, they devised a series of 50-millimeter-thick (2-inch-thick) plates with perimeter finger joints for panel-to-panel connections.

Landesgartenschau Exhibition Hall is the first structure to be made entirely of robot-fabricated plates, according to Stuttgart University.

Landesgartenschau Exhibition Hall is the first structure to be made entirely of robot-fabricated plates, according to Stuttgart University.

Credit: ICD/ITKE/IIGS University of Stuttgart

The unique shapes of the five-, six-, and seven-sided panels, ranging between 1 and 2 meters in length, were generated through custom design tools in Rhino and based on biological principles, the planar approximation of freeform surfaces, the plywood’s material properties, stock availability, the robotic fabrication technique, and workspace. “Due to the computational design process, all panels have different geometries,” says research associate Oliver David Krieg. “Introducing different sided polygons is a natural behavior of the design and simulation process.” Sofistik was used conduct the structural analysis. “It is important to point out that the beech plywood is not used as some sort of interior cladding,” Krieg says. “It is used as the primary load-bearing structure.”

Each panel has a different geometry and connects to its neighbors via perimeter finger joints.

Each panel has a different geometry and connects to its neighbors via perimeter finger joints.

Credit: ICD/ITKE/IIGS University of Stuttgart

The computational design and robotic fabrication workflow was developed over the course of nine months. First, a CNC milling machine cut each panel from a stock piece of beech plywood to its approximate final shape. Two small holes were drilled into each panel for attachment and orientation on the turntable of a seven-axis industrial robot. The robot then used a milling bit to refine the panel edges, finger joints, and screw pockets. Each of the 243 interior panels required about 1 minute of programming and 20 minutes of fabrication time. Nearly all off-cuts were reused as parquet flooring.

The geometry of the panels, which also serves as the support structure, was generated with consideration of the available workspace.

The geometry of the panels, which also serve as the support structure, was generated with consideration of the available workspace.

Credit: ICD/ITKE/IIGS University of Stuttgart

Setup for the panel fabrication

Setup for the panel fabrication

Credit: ICD/ITKE/IIGS University of Stuttgart

In addition to the interior structural panels, the team also prefabricated the building insulation, waterproofing, and ventilated exterior rainscreen, which was made from untreated larch plywood. Prefabrication took a total of four weeks. “The panels were sorted for a fast and easy assembly process, starting on one side of the pavilion in the corner of the larger glass façade and advancing towards the other side,” Krieg says. Because the beech plywood panels are exposed, the team took extra precautions in handling them during transport and assembly.

A worker tightens a crossing screw between panels.

A worker tightens a crossing screw between panels.

Credit: ICD/ITKE/IIGS University of Stuttgart

Onsite construction also took four weeks. Through conventional manual labor, the panels were attached mechanically with crossing screws. At the foundation, a steel angle connects the panels to a wood sill plate on the concrete slab.

Designed for a five-year lifespan, the exhibition hall demonstrates that robot-driven fabrication is a legitimate method for building construction, particularly when designers want to create formal complexity with heterogeneous components and optimize material resources. This effort also bridges the gap between product and building: As plywood is transformed into interlocking panels, the unique construction system becomes inseparable from the final product.

A milling bit was used by the robot to refine the panel edges, finger joints, and screw pockets.

A milling bit was used by the robot to refine the panel edges, finger joints, and screw pockets.

Credit: ICD/ITKE/IIGS University of Stuttgart

The panels were sorterd for an easy assembly process. Construction on-site took four weeks.

The panels were sorterd for an easy assembly process. Construction on-site took four weeks.

Credit: ICD/ITKE/IIGS University of Stuttgart

Credit: ICD/ITKE/IIGS University of Stuttgart

  • Site plan

    Credit: ICD/ITKE/IIGS University of Stuttgart

    Site plan

Section

Section

Credit: ICD/ITKE/IIGS University of Stuttgart

The exterior of the pavilion is clad in untreated larch plywood panels.

The exterior of the pavilion is clad in untreated larch plywood panels.

Credit: ICD/ITKE/IIGS University of Stuttgart

This article expands on Blaine Brownell's earlier coverage of Landesgartenschau Exhibition Hall by the University of Stuttgart. Read his July 1 article, "Robots Prefab a Timber Shell in Germany," here.