Soil cutting experiments and evaluation of an earth auger for a planetary subsurface explorer

Recently planetary exploration that has gathered great attention has a possibility to find trace of life, new substances and origin of our planet especially underground. We have therefore developed a planetary subsurface explorer robot with propulsion and excavation units. The prototype robot demonstrated excellent excavation performance. However, both units have been separately controlled to achieve propulsion and excavation motions. In order to effectively combine these systems, it is therefore desirable to understand an excavation process. The purpose of this study is to reveal the process of the cutting resistance of an earth auger by experiments for the first step. First we conduct two experiments, the pushing force experiment and rotation speed to reveal the excavation process, with a developed experimental device. A torque and vertical force are measured with a 6 axial force sensor as the excavation resistance. Next the excavation resistance of the fish tail comprising the auger head is measured. We observe good excavation results and discuss the excavation process.