Abstract
Because a passive dynamic walking (PDW) robot can walk down shallow slopes using only an initial velocity and gravity, PDW robots are energy efficient. To date, they have been investigated only for shallow slopes and flat surfaces. This paper extends the walking environment to include a small stair step. Here, we use virtual PDW for a biped walking model with semicircular feet. This model has many advantages over the simple PDW model. We analyze the relationships between the height of the small stair step and the model's torque values, and between the height and the time taken to return to stable walking. This enables us to characterize the model's walking capability for a small stair step.
