Autonomous anchoring for robotic construction

Advances in construction automation have tended to focus on either automating conventional earthmoving equipment or on the discrete assembly of superstructure elements. Neither paradigm has addressed anchoring introduced material into soil, a critical task for virtually all useful structures. Simple anchoring can be achieved by driving posts (discrete linear elements) or sheet piles (interlocking profiles) into the ground, serving as a foundation for a later superstructure. In this paper we present Romu, a wheeled robot that uses a combination of a vibratory hammer and its own body mass to drive both posts and piles into the ground. We report on the effects of hardware parameters on pile driving performance, and demonstrate operation in both controlled and natural environments. Romu is first configured to drive interlocking sheet piles. In addition to their utility as foundations, such walls could be useful directly as check dams, interventions used to prevent erosion and promote groundwater recharge in arid regions. We use simulations based on real-world terrains to explore the potential impact of a fleet of such robots deployed over a large watershed region, using a simple reactive approach to dynamically determine dam placement. Romu is then configured to drive a range of readily available building materials that commonly serve as posts. These include wooden slats that can be used for sand fencing, an intervention used to collect wind-blown sand to build barrier dunes. Post driving performance is characterized for a range of materials, and finally the use case of sand fencing is evaluated using physical tests at 1:10 scale in order to predict its potential impact. To broaden the utility of such robots in field settings, directions for future work include refinement of the hardware for improved operation in more terrains, increased capabilities for fuller autonomy, and integration with other construction tasks for more complex projects.