Sample-Based HZD Control for Robustness and Slope Invariance of Planar Passive Bipedal Gaits

Controllers are developed that extend the hybrid zero dynamics (HZD) control approach to the control of planar biped walking by allowing constraints to be designed by sampling a gait of interest, rather than by optimization. The technique is used to enlarge the basin of attraction of a passive biped's gait under the assumption that ideal actuation has been introduced at each of the body coordinates. In this case, no control effort is used at steady-state. The technique also enables the systematic modification of the gaits' kinematic and dynamic properties. The main results are illustrated via two examples