Autonomous dry stone

TLDR

On‑site robotic construction can enable larger, more complex architectural assemblies than laboratory prefabrication while using inexpensive, locally sourced, low‑embodied‑energy materials. The study introduces a process for constructing dry stone walls in situ using a customized autonomous hydraulic excavator. The process employs cabin‑mounted LiDAR for terrain mapping and stone digitization, with a planning algorithm that computes each stone’s placement on‑the‑fly to accommodate unknown material properties and real‑time deviations. The first demonstration produced a 3‑m‑tall wall of 40 stones, each averaging 760 kg.

Abstract

Abstract On-site robotic construction not only has the potential to enable architectural assemblies that exceed the size and complexity practical with laboratory-based prefabrication methods, but also offers the opportunity to leverage context-specific, locally sourced materials that are inexpensive, abundant, and low in embodied energy. We introduce a process for constructing dry stone walls in situ, facilitated by a customized autonomous hydraulic excavator. Cabin-mounted LiDAR sensors provide for terrain mapping, stone localization and digitization, and a planning algorithm determines the placement position of each stone. As the properties of the materials are unknown at the beginning of construction, and because error propagation can hinder the efficacy of pre-planned assemblies with non-uniform components, the structure is planned on-the-fly: the desired position of each stone is computed immediately before it is placed, and any settling or unexpected deviations are accounted for. We present the first result of this geometric- and motion-planning process: a 3-m-tall wall composed of 40 stones with an average weight of 760 kg.