Static Stability Criterion for Walking Robots on Irregular Terrains

Abstract

We discuss some suitable stability margin concepts for walking robots which are expected to walk around on irregular terrains. Several stability margin ideas have been proposed before, but those can be roughly divided into three kinds.We came to the conclusion that a stability margin concept based on energy considerations is the most practical to adopt and that its validity could be recognized through simple experiments. But the existing energy stability margin is inadequate for practical use because this margin varies with the weight of the robot which can't affect its resistance to tumbling caused by slipping from steps or the sudden stop. Therefore, we'll propose an improved one here, called the normalized energy stability margin, the NE stability margin for short. Considering this margin, we'll introduce a novel tool called the SNE contour which connects the points on the slope which have the same NE stability margin, so as to derive a stable gait for walking robots. In the final part of this paper, we focus on the features of the SNE contour which shed new light on the solution for the stable posture.