In situ impact printing with an autonomous legged excavator: System development, integration, and full-scale demonstration

This paper presents an additive manufacturing process, Impact Printing, developed for autonomous on-site construction using in situ resources such as excavated earthen material. The process is enabled by a custom three-subsystem tool that portions and deposits dense, pre-mixed material parts at high velocity, enabling the fabrication of unreinforced architectural structures. To investigate the feasibility of in situ construction, the custom tool is integrated on a mobile autonomous legged excavator. A trajectory-following controller with iterative closest point-based state estimation is implemented to enable accurate motion, while a fabrication-aware software architecture and computational design workflow provides kinematic checking and export of fabrication parameters. The system is validated through the construction of a three-meter-tall wall demonstrator built over multiple days from multiple base positions in a semi-structured outdoor environment. Construction data is post-processed to assess system accuracy, efficiency, and influential parameters, and directions for future development are discussed.