Reinforcement Learning for Versatile, Dynamic, and Robust Bipedal Locomotion Control

The International Journal of Robotics Research (IJRR 2024)

Zhongyu Li (1)    Xue Bin Peng (2)    Pieter Abbeel (1)    Sergey Levine (1)    Glen Berseth (3, 4)    Koushil Sreenath (1)

(1) University of California, Berkeley    (2) Simon Fraser University    (3) Université de Montréal    (4) Mila – Quebec AI Institute

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Abstract

This paper presents a comprehensive study on using deep reinforcement learning (RL) to create dynamic locomotion controllers for bipedal robots. Going beyond focusing on a single locomotion skill, we develop a general control solution that can be used for a range of dynamic bipedal skills, from periodic walking and running to aperiodic jumping and standing. Our RLbased controller incorporates a novel dual-history architecture, utilizing both a long-term and short-term input/output (I/O) history of the robot. This control architecture, when trained through the proposed end-to-end RL approach, consistently outperforms other methods across a diverse range of skills in both simulation and the real world. The study also delves into the adaptivity and robustness introduced by the proposed RL system in developing locomotion controllers. We demonstrate that the proposed architecture can adapt to both time-invariant dynamics shifts and time-variant changes, such as contact events, by effectively using the robot’s I/O history. Additionally, we identify task randomization as another key source of robustness, fostering better task generalization and compliance to disturbances. The resulting control policies can be successfully deployed on Cassie, a torque-controlled human-sized bipedal robot. This work pushes the limits of agility for bipedal robots through extensive realworld experiments. We demonstrate a diverse range of locomotion skills, including: robust standing, versatile walking, fast running with a demonstration of a 400-meter dash, and a diverse set of jumping skills, such as standing long jumps and high jumps.

Paper: [PDF]       Media: [Tech Review]       Preprint: [arXiv]

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Bibtex

@article{
	2024-IJRR-Cassie-Locomotion,
	author = {Zhongyu Li and Xue Bin Peng and Pieter Abbeel and Sergey Levine and Glen Berseth and Koushil Sreenath},
	title ={Reinforcement learning for versatile, dynamic, and robust bipedal locomotion control},
	journal = {The International Journal of Robotics Research},
	volume = {0},
	number = {0},
	pages = {02783649241285161},
	year = {0},
	doi = {10.1177/02783649241285161},
	URL = {https://doi.org/10.1177/02783649241285161},
	eprint = {https://doi.org/10.1177/02783649241285161}
}