Preliminary Study on Role of Finite-sized Foot in Push Recovery of Biped Robot in Sagittal Plane via Stabilization of Divergent Component of Motion

This paper addresses the balance recovery problem for biped robots in the sagittal plane, affected by an instantaneous push. It is particularly seen that, when future footsteps of the robot should be re-generated to deal with a strong push, taking the foot size into account significantly reduces the number of footsteps required for the balance recovery. As an illustration of this idea, we generalize the so-called reactive step generator in the authors' previous work, by employing variation of the zero-moment point inside the supporting region as an additional control input for stabilization of divergent component of motion. On the basis of a mathematical formulation of the balance recovery problem, we verify the validity of the proposed algorithm with both theoretical and simulation results.