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3D Underactuated Bipedal Walking via H-LIP based Gait Synthesis and Stepping Stabilization

Xiong, Xiaobin and Ames, Aaron (2021) 3D Underactuated Bipedal Walking via H-LIP based Gait Synthesis and Stepping Stabilization. . (Unpublished)

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In this paper, we present a Hybrid-Linear Inverted Pendulum (H-LIP) based approach for synthesizing and stabilizing 3D underactuated bipedal walking. The H-LIP model is proposed to capture the essential components of the underactuated part and actuated part of the robotic walking. The walking gait of the robot is then synthesized based on the H-LIP. We comprehensively characterize the periodic orbits of the H-LIP and provably derive their stepping stabilization. The step-to-step (S2S) dynamics of the H-LIP is then utilized to approximate the S2S dynamics of the horizontal state of the center of mass (COM) of the robotic walking, which results in 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 evaluated in both simulation and experiment on the 3D underactuated bipedal robot Cassie, which demonstrate dynamic walking behaviors with both versatility and robustness.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Xiong, Xiaobin0000-0002-6275-3900
Ames, Aaron0000-0003-0848-3177
Additional Information:The original conference version of the paper was presented in IROS 2019 [1], and some results were also presented in Dynamic Walking 2019 [2]. The work is supported by Amazon Fellowship in Artificial Intelligence. The authors are with the Department of Mechanical and Civil Engineering, California Institute of Technology. Corresponding author: Xiaobin Xiong ( The videos of the results can be seen in as well as in [3], [4], [5], [6].
Funding AgencyGrant Number
Amazon Fellowship in Artificial IntelligenceUNSPECIFIED
Subject Keywords:Bipedal Walking, Underactuation, Hybrid-LIP, Stepping Stabilization, Step-to-step Dynamics
Record Number:CaltechAUTHORS:20210225-132701566
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108199
Deposited By: George Porter
Deposited On:01 Mar 2021 15:33
Last Modified:01 Mar 2021 15:33

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