Consideration of Mounted Position of Grousers on Flexible Wheels for Lunar Exploration Rovers to Traverse Loose Soil

Abstract

This paper presents the effectiveness of the flexible wheels for lunar exploration rovers. The flexible wheels have high performance while it is traversing loose soil. The flexible wheel is an effective scheme to traverse loose soil without poor condition. The flexible wheel has the surface which can be changed flexibly toward rough terrain. When the surface of wheel performs matching in a shape of ground to traverse, the normal stress between the wheel and loose soil becomes small. We can prevent from sinking because of the normal stress is small. However, the flexible wheel doesn’t have high performance without grousers. The grouser is very important to get thrust for rovers. From running experiments using single wheel tester, we found that the flexible wheel with grousers has high performance. The mounted positions of grousers on surface of wheel are defined as same angle (ex) 36deg). This means that there are two patterns to mount grousers. One is under rib. Other is between grousers. The spring force under rib is different it between ribs. The spring force under ribs is larger than it between ribs. Moreover, each deformation is different. From these considerations, we need to lead the optimal position for grousers. We carried out running experiments using wheel with both pattern. On experiments, we understood the wheel with the position mounted between ribs is better performance than it set under rib. When the area given normal stress is wide, soil under wheel becomes hard. Therefore, the wheel with grousers mounted between ribs has higher performance compared with it mounted under ribs.