Advancing construction in existing contexts: Prospects and barriers of 3d printing with mobile robots for building maintenance and repair

Mobile robots for 3D printing applications are ready to transition from factory floors to building sites. Their remarkable flexibility and adaptability support a variety of deposition-based 3D printing technologies that utilise materials ranging from concrete and earth for extrusion, spraying, or shotcreting to metals for processes like Wire Arc Additive Manufacturing. Not confined to new constructions alone, their mobility enables utilisation in corrective building maintenance, restoration, revitalisation, and repair. Their ability to cooperate with one another allows for deployment in multi-robot settings, offering scalability in speed by their number. Despite their promising potential, mobile 3D printing robots also encounter numerous technological challenges. These include ensuring the mechanical properties of printed structures meet required building codes, designing robust mechanical systems for large-scale construction projects, and integrating these systems seamlessly with existing architectural planning tools. Moreover, enhancing the precision and robustness of these robots through advanced sensing and control technologies is critical for their effective application in building manufacturing. With this paper, we detail selected current research trajectories and give insights into current challenges, open questions, and key prospects associated with mobile 3D printing robots for on-site construction within existing environments. To enrich the discussion, insights into potential architectural application scenarios for revitalising, repairing, and strengthening building structures are provided. The complex, interdisciplinary nature of these challenges underscores the need for a collaborative approach in advancing the field of mobile 3D printing technology.