Abstract
This paper concerns an analysis of a quasi-passive dynamic walking (quasi-PDW) biped robot on level ground. In this study, a linearized "simplest walking model" is adopted as the biped walker model, and the constant torque inputs at the hip joints which simulate the effect of the gravity on a slope are introduced to make the quasi-PDW on level ground to have a periodic walking motion. The equilibrium points of the Poincare map and their dependence on the input torque are numerically studied, and the structure of the domains of attraction is investigated. A control algorithm which enhances the stability of the equilibrium is proposed based on the linearized Poincare map, and the optimal gain is designed in terms of the pole assignment to maximize the local stability of the equilibrium. In addition, a study concerning the stride control is carried out, and based on the structure of the domains of attraction, the existence of a control law that can direct the walker from one equilibrium to another for a desired stride is suggested.
