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| | Wenhao Zhang1,2,Peng Song1,et al.[en_title][J].Control Theory and Technology,2024,22(1):56~68.[Copy] |
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| Unknown system dynamics estimator-based impedance control for lower limb exoskeleton with enhanced performance |
| WenhaoZhang1,2,PengSong1,2,MingyingWu1,QiangLi1,2,XinminMo1,2,PingxinJi1,2,3 |
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| (1 Northwest Institute of Mechanical and Electrical Engineering, Xianyang 712099, Shaanxi, China;
2 Xi’an Exo-Smart Dynamics Technology Ltd., Xi’an 712046, Shaanxi, China;;3 Department of Mechanical and Engineering, Beijing Institute of Technology, Beijing 100081, China.) |
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| 摘要: |
| In this article, an unknown system dynamics estimator-based impedance control method is proposed for the lower limb
exoskeleton to stimulate the tracking flexibility with the terminal target position when suffering parametric inaccuracies and
unexpected disturbances. To reinforce the robust performance, via constructing the filtering operation-based dynamic relation,
i.e., invariant manifold, the unknown system dynamics estimators are employed to maintain the accurate perturbation identifi-
cation in both the hip and knee subsystem. Besides, a funnel control technique is designed to govern the convergence process
within a minor overshoot and a higher steady-state precision. Meanwhile, an interactive complaint result can be obtained with
the aid of the impedance control, where the prescribed terminal trajectory can be adjusted into the interaction variable-based
target position by the force–position mapping, revealing the dynamic influence between the impedance coefficient (stiffness
and damping) and the adjusted position magnitude. A sufficient stability analysis verifies the ultimately uniformly bounded
results of all the error signals, and even the angle errors can be regulated within the predefined funnel boundary in the whole
convergence. Finally, some simulations are provided to demonstrate the validity and superiority including the enhanced
interaction flexibility and robustness. |
| 关键词: Trajectory tracking · Invariant manifold · Funnel control · Impedance control · Lower limb exoskeleton |
| DOI：https://doi.org/10.1007/s11768-023-00189-0 |
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| 基金项目:This work was supported in part by the Young Talent Fund of Association for Science and Technology in Shaanxi, China (No. 20230126). |
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| Unknown system dynamics estimator-based impedance control for lower limb exoskeleton with enhanced performance |
| Wenhao Zhang1,2,Peng Song1,2,Mingying Wu1,Qiang Li1,2,Xinmin Mo1,2,Pingxin Ji1,2,3 |
| (1 Northwest Institute of Mechanical and Electrical Engineering, Xianyang 712099, Shaanxi, China;
2 Xi’an Exo-Smart Dynamics Technology Ltd., Xi’an 712046, Shaanxi, China;;3 Department of Mechanical and Engineering, Beijing Institute of Technology, Beijing 100081, China.) |
| Abstract: |
| In this article, an unknown system dynamics estimator-based impedance control method is proposed for the lower limb
exoskeleton to stimulate the tracking flexibility with the terminal target position when suffering parametric inaccuracies and
unexpected disturbances. To reinforce the robust performance, via constructing the filtering operation-based dynamic relation,
i.e., invariant manifold, the unknown system dynamics estimators are employed to maintain the accurate perturbation identifi-
cation in both the hip and knee subsystem. Besides, a funnel control technique is designed to govern the convergence process
within a minor overshoot and a higher steady-state precision. Meanwhile, an interactive complaint result can be obtained with
the aid of the impedance control, where the prescribed terminal trajectory can be adjusted into the interaction variable-based
target position by the force–position mapping, revealing the dynamic influence between the impedance coefficient (stiffness
and damping) and the adjusted position magnitude. A sufficient stability analysis verifies the ultimately uniformly bounded
results of all the error signals, and even the angle errors can be regulated within the predefined funnel boundary in the whole
convergence. Finally, some simulations are provided to demonstrate the validity and superiority including the enhanced
interaction flexibility and robustness. |
| Key words: Trajectory tracking · Invariant manifold · Funnel control · Impedance control · Lower limb exoskeleton |
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