Proposal of both-end supported earth auger for bending excavation of peristaltic-type lunar excavation robot

Abstract

We have developed a lunar subsurface excavation robot using peristaltic crawling motion of an earthworm. This robot, which excavates soil by earth auger and propels in the hole by peristaltic crawling, excavated 938 mm and shew its usefulness. Nowadays, we challenge to the bending excavation for widespread exploration. We have developed a flexible excavation unit, which improved earth auger and shown it usefulness before. However, the earth auger often causes axial runout because it is cantilevering. Axial runout lead to unexpected expansion of borehole diameter. The diameter of borehole grows wider, the robot gets less able to propel. We consider that axis runout is more often occurred in the flexible excavation unit because it uses universal joint for bending point. Therefore, in this paper, we propose a both-end supported earth auger to reduce axial runout and demonstrate its performance by comparing it to the existing cantilevering earth auger.