Human-like actuated walking that is asymptotically stable without feedback

Studies a two-legged kneed walking robot with point feet. At any given moment, only one foot is in contact with the ground, and the switching is instantaneous. The robot can be considered as a simplified model of human walking. The periodic torque histories applied to each link are a priori prescribed for a motion and are not changed by any feedback interference. Nevertheless the robot is capable of naturally recovering from perturbations, returning to standard gait-a property that we call open-loop stable. We formulate the problem of open-loop stabilization as an optimal control problem. Design parameters and periodic torque inputs that lead to a stable configuration are computed using a two-level optimization procedure. We believe that this is the first demonstration of the ability to create stable actuated open-loop gaits of bipedal walking robots.