Smart Dynamic Casting: Slipforming with Flexible Formwork - Inline Measurement and Control

Abstract

Smart Dynamic Casting (SDC) – a robotic prefabrication method for non-standard structures – has emerged from shaping concrete with a rigid formwork into an almost fully automated system enabling the production of concrete structures with variable cross-section and geometries using flexible actuated formworks. The flexible formwork systems have yielded full scale prototypes (up to 3 meters in height) that vary in shape, volume, thickness and geometry (or a combination of these), and show that the SDC design space can be significantly expanded, far beyond what has been achieved in previous studies. Two different shaping methods were applied. The first method shapes the material locally, at the exit of the formwork, only allowing a minimal gradient of deformation. The second method shapes the material globally, across the whole height of formwork, allowing for significant variation in cross section. Regardless of whether the deformation occurs locally or globally, any deformation modifies the load on the concrete at the exit of the formwork, thus requiring continuous inline measurements and automated feedback loops. A recent successful approach combines formwork pressure and friction measurements to define the lower and upper strength limits of the shaping window, thereby enabling more robust control of the process. This paper presents the current SDC process, with a particular emphasis on how the experimental setup has changed from previous studies. This includes descriptions of new flexible formwork typologies, followed by a description of the novel inline measurement technique. Together, these advances bring the SDC system another step closer to the main objective of the research, which is to develop a fully automated system that enables efficient production of load bearing structures in a continuous digital chain.