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A Hierarchical Control Scheme for Active Power-assist Lower-limb Exoskeletons

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Abstract

Effectively controlling active power-assist lower-limb exoskeletons in a human-in-the-loop manner poses a substantial challenge, demanding an approach that ensures wearer autonomy while seamlessly adapting to diverse wearer needs. This paper introduces a novel hierarchical control scheme comprising five integral components: intention recognition layer, dynamics feedforward layer, force distribution layer, feedback compensation layer, as well as sensors and actuators. The intention recognition layer predicts the wearer’s movement and enables wearer-dominant movement through integrated force and position sensors. The force distribution layer effectively resolves the statically indeterminate problem in the context of double-foot support, showcasing flexible control modes. The dynamics feedforward layer mitigates the effect of the exoskeleton itself on movement. Meanwhile, the feedback compensation layer provides reliable closed-loop control. This approach mitigates abrupt changes in joint torques during frequent transitions between swing and stance phases by decomposed dynamics. Validating this innovative hierarchical control scheme on a hydraulic exoskeleton platform through a series of experiments, the results demonstrate its capability to deliver assistance in various modes such as step**, squatting, and jum** while adapting seamlessly to different terrains.

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Data Availability Statement

The datasets generated and analyzed during the current study are not publicly available, as the data also forms part of an ongoing study but are available from the corresponding author on reasonable request.

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Acknowledgements

This work was supported by the China Postdoctoral Science Foundation (No. 2020M672823), National Natural Science Foundation of China National Natural Science Foundation of China (No. 52305072, U2013602), Natural Science Foundation of Hebei Province of China (No. E2022203095), Shenzhen Science and Technology Program (No. JSGG20201102152602007), Shenzhen Science and Technology Research and Development Foundation (No. JCYJ20190813171009236), and Basic Scientific Research of Technology (No. JCKY2020603C009).

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Authors and Affiliations

  1. State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin, 150001, Heilongjiang, China

    **g Deng, Haibo Gao & Yapeng Shi

  2. Shenzhen Academy of Aerospace Technology, Shenzhen, 518063, China

    **g Deng & Wenzheng Jiang

  3. Faculty of Computing, Harbin Institute of Technology, Harbin, 150001, Heilongjiang, China

    Yapeng Shi

  4. Institute of Intelligent Manufacturing Technology, Shenzhen Polytechnic University, Shenzhen, 518055, China

    Mantian Li

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Correspondence to Yapeng Shi.

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Deng, J., Jiang, W., Gao, H. et al. A Hierarchical Control Scheme for Active Power-assist Lower-limb Exoskeletons. J Bionic Eng (2024). https://doi.org/10.1007/s42235-024-00561-z

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