Chasing Stability: Humanoid Running via Control Lyapunov Function Guided Reinforcement Learning

Fuente: arXiv
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Auteurs principaux: Olkin, Zachary, Li, Kejun, Compton, William D., Ames, Aaron D.
Format: Preprint
Publié: 2025
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author Olkin, Zachary
Li, Kejun
Compton, William D.
Ames, Aaron D.
author_facet Olkin, Zachary
Li, Kejun
Compton, William D.
Ames, Aaron D.
contents Achieving highly dynamic behaviors on humanoid robots, such as running, requires controllers that are both robust and precise, and hence difficult to design. Classical control methods offer valuable insight into how such systems can stabilize themselves, but synthesizing real-time controllers for nonlinear and hybrid dynamics remains challenging. Recently, reinforcement learning (RL) has gained popularity for locomotion control due to its ability to handle these complex dynamics. In this work, we embed ideas from nonlinear control theory, specifically control Lyapunov functions (CLFs), along with optimized dynamic reference trajectories into the reinforcement learning training process to shape the reward. This approach, CLF-RL, eliminates the need to handcraft and tune heuristic reward terms, while simultaneously encouraging certifiable stability and providing meaningful intermediate rewards to guide learning. By grounding policy learning in dynamically feasible trajectories, we expand the robot's dynamic capabilities and enable running that includes both flight and single support phases. The resulting policy operates reliably on a treadmill and in outdoor environments, demonstrating robustness to disturbances applied to the torso and feet. Moreover, it achieves accurate global reference tracking utilizing only on-board sensors, making a critical step toward integrating these dynamic motions into a full autonomy stack.
format Preprint
id arxiv_https___arxiv_org_abs_2509_19573
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Chasing Stability: Humanoid Running via Control Lyapunov Function Guided Reinforcement Learning
Olkin, Zachary
Li, Kejun
Compton, William D.
Ames, Aaron D.
Robotics
Achieving highly dynamic behaviors on humanoid robots, such as running, requires controllers that are both robust and precise, and hence difficult to design. Classical control methods offer valuable insight into how such systems can stabilize themselves, but synthesizing real-time controllers for nonlinear and hybrid dynamics remains challenging. Recently, reinforcement learning (RL) has gained popularity for locomotion control due to its ability to handle these complex dynamics. In this work, we embed ideas from nonlinear control theory, specifically control Lyapunov functions (CLFs), along with optimized dynamic reference trajectories into the reinforcement learning training process to shape the reward. This approach, CLF-RL, eliminates the need to handcraft and tune heuristic reward terms, while simultaneously encouraging certifiable stability and providing meaningful intermediate rewards to guide learning. By grounding policy learning in dynamically feasible trajectories, we expand the robot's dynamic capabilities and enable running that includes both flight and single support phases. The resulting policy operates reliably on a treadmill and in outdoor environments, demonstrating robustness to disturbances applied to the torso and feet. Moreover, it achieves accurate global reference tracking utilizing only on-board sensors, making a critical step toward integrating these dynamic motions into a full autonomy stack.
title Chasing Stability: Humanoid Running via Control Lyapunov Function Guided Reinforcement Learning
topic Robotics
url https://arxiv.org/abs/2509.19573