Whole-Body Constrained Learning for Legged Locomotion via Hierarchical Optimization

Fuente: arXiv
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Autori principali: Wang, Haoyu, Zhou, Ruyi, Ding, Liang, Liu, Tie, Zhang, Zhelin, Xu, Peng, Gao, Haibo, Deng, Zongquan
Natura: Preprint
Pubblicazione: 2025
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author Wang, Haoyu
Zhou, Ruyi
Ding, Liang
Liu, Tie
Zhang, Zhelin
Xu, Peng
Gao, Haibo
Deng, Zongquan
author_facet Wang, Haoyu
Zhou, Ruyi
Ding, Liang
Liu, Tie
Zhang, Zhelin
Xu, Peng
Gao, Haibo
Deng, Zongquan
contents Reinforcement learning (RL) has demonstrated impressive performance in legged locomotion over various challenging environments. However, due to the sim-to-real gap and lack of explainability, unconstrained RL policies deployed in the real world still suffer from inevitable safety issues, such as joint collisions, excessive torque, or foot slippage in low-friction environments. These problems limit its usage in missions with strict safety requirements, such as planetary exploration, nuclear facility inspection, and deep-sea operations. In this paper, we design a hierarchical optimization-based whole-body follower, which integrates both hard and soft constraints into RL framework to make the robot move with better safety guarantees. Leveraging the advantages of model-based control, our approach allows for the definition of various types of hard and soft constraints during training or deployment, which allows for policy fine-tuning and mitigates the challenges of sim-to-real transfer. Meanwhile, it preserves the robustness of RL when dealing with locomotion in complex unstructured environments. The trained policy with introduced constraints was deployed in a hexapod robot and tested in various outdoor environments, including snow-covered slopes and stairs, demonstrating the great traversability and safety of our approach.
format Preprint
id arxiv_https___arxiv_org_abs_2506_05115
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Whole-Body Constrained Learning for Legged Locomotion via Hierarchical Optimization
Wang, Haoyu
Zhou, Ruyi
Ding, Liang
Liu, Tie
Zhang, Zhelin
Xu, Peng
Gao, Haibo
Deng, Zongquan
Robotics
Reinforcement learning (RL) has demonstrated impressive performance in legged locomotion over various challenging environments. However, due to the sim-to-real gap and lack of explainability, unconstrained RL policies deployed in the real world still suffer from inevitable safety issues, such as joint collisions, excessive torque, or foot slippage in low-friction environments. These problems limit its usage in missions with strict safety requirements, such as planetary exploration, nuclear facility inspection, and deep-sea operations. In this paper, we design a hierarchical optimization-based whole-body follower, which integrates both hard and soft constraints into RL framework to make the robot move with better safety guarantees. Leveraging the advantages of model-based control, our approach allows for the definition of various types of hard and soft constraints during training or deployment, which allows for policy fine-tuning and mitigates the challenges of sim-to-real transfer. Meanwhile, it preserves the robustness of RL when dealing with locomotion in complex unstructured environments. The trained policy with introduced constraints was deployed in a hexapod robot and tested in various outdoor environments, including snow-covered slopes and stairs, demonstrating the great traversability and safety of our approach.
title Whole-Body Constrained Learning for Legged Locomotion via Hierarchical Optimization
topic Robotics
url https://arxiv.org/abs/2506.05115