Learn Weightlessness: Imitate Non-Self-Stabilizing Motions on Humanoid Robot

Fuente: arXiv
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Main Authors: Xin, Yucheng, Bao, Jiacheng, Yang, Haoran, Que, Wenqiang, Wang, Dong, Tan, Junbo, Wang, Xueqian, Zhao, Bin, Li, Xuelong
Format: Preprint
Published: 2026
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author Xin, Yucheng
Bao, Jiacheng
Yang, Haoran
Que, Wenqiang
Wang, Dong
Tan, Junbo
Wang, Xueqian
Zhao, Bin
Li, Xuelong
author_facet Xin, Yucheng
Bao, Jiacheng
Yang, Haoran
Que, Wenqiang
Wang, Dong
Tan, Junbo
Wang, Xueqian
Zhao, Bin
Li, Xuelong
contents The integration of imitation and reinforcement learning has enabled remarkable advances in humanoid whole-body control, facilitating diverse human-like behaviors. However, research on environment-dependent motions remains limited. Existing methods typically enforce rigid trajectory tracking while neglecting physical interactions with the environment. We observe that humans naturally exploit a "weightless" state during non-self-stabilizing (NSS) motions--selectively relaxing specific joints to allow passive body--environment contact, thereby stabilizing the body and completing the motion. Inspired by this biological mechanism, we design a weightlessness-state auto-labeling strategy for dataset annotation; and we propose the Weightlessness Mechanism (WM), a method that dynamically determines which joints to relax and to what level, together enabling effective environmental interaction while executing target motions. We evaluate our approach on 3 representative NSS tasks: sitting on chairs of varying heights, lying down on beds with different inclinations, and leaning against walls via shoulder or elbow. Extensive experiments in simulation and on the Unitree G1 robot demonstrate that our WM method, trained on single-action demonstrations without any task-specific tuning, achieves strong generalization across diverse environmental configurations while maintaining motion stability. Our work bridges the gap between precise trajectory tracking and adaptive environmental interaction, offering a biologically-inspired solution for contact-rich humanoid control.
format Preprint
id arxiv_https___arxiv_org_abs_2604_21351
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Learn Weightlessness: Imitate Non-Self-Stabilizing Motions on Humanoid Robot
Xin, Yucheng
Bao, Jiacheng
Yang, Haoran
Que, Wenqiang
Wang, Dong
Tan, Junbo
Wang, Xueqian
Zhao, Bin
Li, Xuelong
Robotics
The integration of imitation and reinforcement learning has enabled remarkable advances in humanoid whole-body control, facilitating diverse human-like behaviors. However, research on environment-dependent motions remains limited. Existing methods typically enforce rigid trajectory tracking while neglecting physical interactions with the environment. We observe that humans naturally exploit a "weightless" state during non-self-stabilizing (NSS) motions--selectively relaxing specific joints to allow passive body--environment contact, thereby stabilizing the body and completing the motion. Inspired by this biological mechanism, we design a weightlessness-state auto-labeling strategy for dataset annotation; and we propose the Weightlessness Mechanism (WM), a method that dynamically determines which joints to relax and to what level, together enabling effective environmental interaction while executing target motions. We evaluate our approach on 3 representative NSS tasks: sitting on chairs of varying heights, lying down on beds with different inclinations, and leaning against walls via shoulder or elbow. Extensive experiments in simulation and on the Unitree G1 robot demonstrate that our WM method, trained on single-action demonstrations without any task-specific tuning, achieves strong generalization across diverse environmental configurations while maintaining motion stability. Our work bridges the gap between precise trajectory tracking and adaptive environmental interaction, offering a biologically-inspired solution for contact-rich humanoid control.
title Learn Weightlessness: Imitate Non-Self-Stabilizing Motions on Humanoid Robot
topic Robotics
url https://arxiv.org/abs/2604.21351