Static Stability of Double-Spiral Mobile Robot over Rough Terrain

In this paper, we investigate static stability for a doublespiral mobile robot. It is a new locomotion mechanism suitable for the wetlands that suppresses damage to vegetation and does not sink in the mud. The robot walks on the spirals, which play the role of footholds for the mobile robot. To overcome rough terrain locomotion, we need to ensure the stability of the walking motion on the sloping ground. In this study, we applied normalized energy stability margin (NESM) to the double-spiral mobile robot in order to investigate its static stability over rough terrain. The procedure to derived the NESM value were shown from the point of view of the vector calculation. In the numerical case study, we drew NESM maps to investigate the static stabilities when the inclination of the slope varied or the pose and orientation of the robot changed. We adopted a moment in the swing phase where the stability of the robot’s balance was easily lost. We found that the robot has sensitive directions in terms of stability. Planning the route and motion of the robot in the rough terrain could help maintain its stability.