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.