Abstract
It was clarified that energy-efficient dynamic bipedal walking can be achieved by effectively applying the principle of passive dynamic walking. Approaches based on virtual gravity are typical methods for generating efficient level dynamic gait. These methods, however, had the problem that the specified control input includes a singular point which causes complicated motion. This paper then proposes a new method, which is termed as the pseudo virtual passive dynamic walking, to solve this problem. We first formulate the basic method for a planar underactuated biped model with an upper body by introducing the concept of pseudo center of mass. We also consider to inhibit swing-leg retraction by constraining the impact posture to achieve the maximum efficiency condition. In addition, we discovered that the constraint on impact posture strongly extends the stable domain and improves the convergence speed to the steady gait through numerical simulations. We report the detailed analysis results and theoretically investigate how the constraint affects the gait properties.
