Crafting structural timber trusses from irregular offcuts via human–robot interaction

Working with irregular, reclaimed, and non-standard materials is essential to reducing the environmental impact of construction. Yet most robotic design-to-fabrication workflows rely on uniform components and predefined plans. This disconnect reflects a missed opportunity: material uncertainty, rather than being treated as a constraint, can become a catalyst for creativity when made actionable through well-designed human–robot interfaces. Building on the Truss from Trash framework, this paper presents an extended human–robot system for the adaptive assembly of timber trusses from offcuts. A projection-based interface embeds interaction within the fabrication environment, allowing users to select materials and adjust the design using tangible tokens, while real-time overlays provide member assignment guidance and cut previews. An on-demand form-finding component supports decision-making by validating equilibrium for user edits and proposing feasible design adaptations based on available stock. Validated changes propagate to the robot, which executes pick-cut-place cycles to incrementally assemble the structure. Through fabrication experiments, we show how our system enables users to reconcile material availability, design intent, and structural feasibility alongside fabrication.