Robotic on-site adaptive thin-layer printing: Challenges and workflow for design and fabrication of bespoke cementitious plasterwork at full architectural scale

This paper describes the 1:1 scale application of Robotic Plaster Spraying (RPS), a novel, adaptive thin-layer printing technique, using cementitious base coat plaster, realized in a construction setting. In this technique, the print layers are vertical unlike most 3DCP processes. The goal is to explore the applicability and scalability of this spray-based printing technique. In this study, RPS is combined with an augmented interactive design setup, the Interactive Robotic Plastering (IRoP), which allows users to design directly on the construction site, taking the building structure, as-built state of the on-going fabrication and the material behavior into consideration. The experimental setup is an on-site robotic system that consists of a robotic arm mounted on a semi-mobile vertical axis with an integrated, automated pumping and adaptive spraying setup that is equipped with a depth camera. The user interaction is enabled by a controller-based interaction system, interactive design tools, and an augmented reality interface. The paper presents the challenges and the workflow that is needed to work with a complex material system on-site to produce bespoke plasterwork. The workflow includes an interactive design procedure, localization on-site, process control and a data collection method that enables predicting the behavior of complex-to-simulate cementitious material. The results demonstrate the applicability and scalability of the adaptive thin-layer printing technique and address the challenges, such as maintaining material continuity and working with unpredictable material behavior during the fabrication process.