Abstract
The purpose of this paper is to analyze the stability of Passive Dynamic Walking using Poincaré map of the impact point which is the state of walking robot at the collision between a swing leg and ground. Especially, in this paper, we focus on the feedback structure which exist in equations which are used to get the Poincaré map, and consider the relationship between stability of Passive Dynamic Walking and the feedback structure focusing on the relationship to LQR or output zeroing control.