Footer Module Systems for Discrete Metamaterials Structure Construction in Lunar Environments

This paper proposes a modular footing system to stabilize and transfer the load to the supporting material and uneven terrains. Such systems must overcome challenges presented by the lunar regolith’s low soil cohesion and high settlement. The proposed footing system strategically leverages the structure of voxels and the capabilities of periodic lattice-traversing robots to adapt to the terrain, topology, and gradient. Potential footing modules are designed to be both robotically attached to a voxel’s base and robotically actuated. To maintain interoperability with current robotic systems, the proposed solutions assume a cuboctahedron voxel unit with a twelve-inch minimum distance between faces. The proposed footing system distributes load onto the lunar soil and isolates the structure from surface vibrations/seismic interactions by strategically locating several footing modules beneath the voxel structure. To adapt to the topology and terrain, an individual footing module allows robotic height adjustment to ensure an appropriate structure-ground interface, detect the ground to apply pressure and min-imize settlement, and adapt to the topology while gripping the surface. Accordingly, the solution space is comprised of three independent dimensions: voxel integration, actuation, and surface interfacing. These three dimensions define necessary features and functions for potential footing modules. Potential solutions are optimized for loading moments, stabilizing the structure, actuating with minimal error, and retracting for reuse. To compare solutions, several footing modules were designed and then rated based on parameters such as volume occupied, total mass, and ease of actuation. Ultimately, such systems also enable robotic stabilization by adjusting footer heights on demand to develop a level voxel surface. Issues which need to be addressed in future work include accounting for thermal deformations in the lunar soil.