Validation of the measuring condition for a planetary subsurface explorer robot that uses peristaltic crawling

Subsurface exploration is required to obtain resources such as oil and minerals, and to construct buildings and houses. It would also be necessary in any future expansion of human activity on the Moon or other planets. We have developed a small unmanned planetary subsurface explorer suitable for nascent stages of exploration. The subsurface excavator consists of both propulsion and excavation units, and its movements are based on those of an actual earthworm. The prototype excavator showed good performance in excavation experiments, and it could excavate at the same depth as in its own weight in the case of an excavator that is 1/6th of its own weight using counterweights. It was difficult to obtain and evaluate an underground environment and the right condition for an excavator in the excavation process. Therefore, we improved a propulsion unit equipped with sensors to detect the pushing force in a radial direction and then performed excavation experiments using the improved excavator from a launcher. We discuss data obtained from sensors, the excavation depth and motor torque. Our excavator showed good performance.