Scaffold-free cooperative robotic disassembly and reuse of a timber structure in the ZeroWaste project

ZeroWaste as a project aims to reposition existing timber building stock within a circular economy framework, reframing them as valuable resources for reuse rather than disposal. This paper presents the computational methods and physical construction outcomes of the project, showcasing how the circular economy principles of reuse and reduced material consumption can be actualized through cooperative robotic fabrication. Initially, a pavilion-scale prototype, mirroring conventional North American stick frame construction, is constructed. A robotic cell, equipped with three large-scale robotic arms and 3D cameras, is used to generate precise as-built geometric data on the prototype, which is used for planning robotic processes. A novel topological representation of a structure, the support hierarchy graph, is developed and used to generate candidate fabrication sequences. These sequences are then assessed for robotic execution and structural feasibility. Leveraging the cooperative nature of the setup, these sequences are planned without requiring external scaffolding for structural stability as the robots are used to provide temporary support during the fabrication process. Three physical case studies validate the developed computational and cooperative robotic workflow. In Phase 1 we perform a small-scale disassembly intervention by planning the removal of a single member. In Phase 2 we expand the disassembly scope to the full South wall and perform a minor reassembly at the end of the disassembly sequence. In Phase 3 we expand the scope further, disassembling all remaining members in the West wall and roof sub-structures while performing a concurrent one-to-one reassembly process, where each member removed is placed back into the structure to turn the typical stud wall into a stiffer lattice structure. The successful completion of the three case studies demonstrates the potential for existing buildings to serve as reservoirs of reusable materials through scaffold-free cooperative robotic disassembly and reassembly.