3D Underactuated Bipedal Walking via H-LIP based Gait Synthesis and Stepping Stabilization
This addresses the challenge of stable locomotion for underactuated bipedal robots, which is incremental as it builds on existing H-LIP concepts with hardware realization.
The paper tackles the problem of 3D underactuated bipedal walking by proposing a Hybrid-Linear Inverted Pendulum (H-LIP) approach for gait synthesis and stepping stabilization, achieving dynamic and stable walking on the Cassie robot with high versatility and robustness in simulation and experiment.
In this paper, we holistically present a Hybrid-Linear Inverted Pendulum (H-LIP) based approach for synthesizing and stabilizing 3D foot-underactuated bipedal walking, with an emphasis on thorough hardware realization. The H-LIP is proposed to capture the essential components of the underactuated and actuated part of the robotic walking. The robot walking gait is then directly synthesized based on the H-LIP. We comprehensively characterize the periodic orbits of the H-LIP and provably derive the stepping stabilization via its step-to-step (S2S) dynamics, which is then utilized to approximate the S2S dynamics of the horizontal state of the center of mass (COM) of the robotic walking. The approximation facilities a H-LIP based stepping controller to provide desired step sizes to stabilize the robotic walking. By realizing the desired step sizes, the robot achieves dynamic and stable walking. The approach is fully evaluated in both simulation and experiment on the 3D underactuated bipedal robot Cassie, which demonstrates dynamic walking behaviors with both high versatility and robustness.