Ashley Miller graduate presentation
In the United States, most trees destined to be cut into lumber are grown in managed forests either owned by the lumber company or leased from the government. After the trees have reached an appropriate size, they are cut down and transported to a lumber mill where they are cut into various sizes of lumber. Parts of not easily sawn trees are often ground down into other materials like wood chips and sawdust among many other things. The leading question among many different researchers including the ones in this presentation is:
Can we make more with what we are already using?
Log knot Cornell Robotic Construction Laboratory (RCL)
This project outlines processes and methodologies for robotic fabrication, variable complex-curvature creation, joinery detailing, geometric and structural optimization, the reduction of moisture-related material failures, and on-site assembly. First, the research team developed a design method to create curvature from roundwood pieces, both regular and irregular. Components are computationally processed to form a spatially complex figure-eight knot (Savoy knot). Based on initial 3D models, a number of irregularly shaped trees and small roundwood members that cannot be processed by traditional sawmills are selected and harvested from a local forest. To complete the design process from form-to-log towards log-to-form, the trees are 3D scanned and the 3D model is adjusted to fit the available timber stock inventory. Second, the structure is computationally optimized and fabrication protocols are developed for the available robotic system, a KUKA KR200/2 with a 5hp CNC spindle. Custom computational solvers locally optimize the structure for bending and tension at each tri-fold mortise and tenon joint and custom fabrication protocols improve the positioning of a work piece in relation to the robotic end effector.
Due to the unique joint design, LOG KNOT requires only minimal formwork for assembly and can be built without heavy machinery. The main research contributions of this architectural installation are in the area of minimal formwork assembly, bending and tension force optimization of mortise and tenon joints, as well as variable 3D compound curvature creation for regular and irregular roundwood geometries.
Working primarily with timber from the Hooke Park estate, students of the Architectural Association’s Design & Make program engage with design through the prototyping and construction of experimental buildings. This year, students completed a robotically fabricated Wood Chip Barn which employs twenty beech forks within an arching Vierendeel style truss. The building provides 400cu.m of storage for biofuel and will enable the estate to use its own timber for renewable heat production.
Deriving non-standard components from wood’s natural forms, the truss makes full use of the capabilities of new technologies. 3D-scanning and evolutionary optimization of the placement of each component within a structurally determined arch, along with customized robotic fabrication lead to an alternative conception of material in which inherent irregular geometries are actively exploited by non-standard technologies. The rationale for this approach is that the diverse characteristics of near-site material can be economically exploited without remote industrial processing.
A goal for the project was to exploit the moment resisting capacity of tree forks. In a standing tree the naturally occurring forks exhibit remarkable strength and material efficiency, and before processing, already present what digital tools are commonly employed in pursuit of a non-standard series.
Having surveyed Hooke Park’s woodland, a database of 204 potential forks was established, and from it, the structural concept developed. Based on the criteria of this structure, 25 forks were harvested, brought back to the campus and scanned in 3D. An organization script was used to arrange the forks in collaboration with Arup. This digital model was then translated into fabrication information with which a six-axis robotic arm transformed each fork into a finished component. Elements of the truss were pre-assembled in Hooke Park’s Big Shed before being erected on site. Spanning 25m from front to back and 10m side to side, the arching truss rises to 8.5m at its zenith.
Overall, AI-assisted construction is in its’ infancy. There is no real way for progress with out hundreds of hours of committed research and prototyping. But with much perseverance and determination, this construction method could save thousands of tons of offcuts from becoming mulch and other less useable material to be made into structures that can be used for generations.
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