Seamless Reaction Strategy for Bipedal Locomotion Exploiting Real-Time Nonlinear Model Predictive Control

This letter presents a reactive locomotion method for bipedal robots enhancing robustness and external disturbance rejection performance by seamlessly rendering several walking strategies of the ankle, hip, and footstep adjustment. The Nonlinear Model Predictive Control (NMPC) is formulated to take into account nonlinear Divergent Component of Motion (DCM) error dynamics that predicts the future states of the robot in response to the walking strategies. This formulated NMPC enables the seamless application of these strategies improving push disturbance rejection performance. The proposed controller is validated in simulation and through an experiment on a bipedal robot platform, Gazelle, which confirms its effectiveness in real-time.