Estimating human joint moments unifies exoskeleton control, reducing user effort

Molinaro, Dean D.; Kang, Inseung; Young, Aaron J.

doi:10.1126/scirobotics.adi8852

Cited by 19 publications

(1 citation statement)

References 66 publications

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“…Lastly, an intuitive task-invariant approach is to quantitatively estimate the user's instantaneous action, and generate the assistive action as a function of it. This can be in the form of proportional myoelectric control 17 in which muscle activations are mapped to assistive torques, or proportional joint moment control 18,19 where the assistive torques are determined by the estimated biological joint moments.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Hip Exoskeleton Control using Heart Rate Feedback Reduces Oxygen Cost during Ecological Locomotion

Manzoori,

Malatesta,

Mortier

et al. 2024

Preprint

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Despite their potential, exoskeletons have not reached widespread adoption in daily life, partly due to the challenge of seamlessly adapting assistance across various tasks and environments. Task-specific designs, reliance on complex sensing and extensive data-driven training often limit the practicality of the existing control strategies. To address this challenge, we introduce an adaptive control strategy for hip exoskeletons, emphasizing minimal sensing and rapid deployability. Using only insole pressure and heart rate (HR) sensing, the controller modulates assistance across various locomotion tasks. We evaluated this strategy with twelve able-bodied participants in a real-world scenario including level walking, stairs, and inclines. The controller successfully adapted assistance timing and amplitude to different activities. This resulted in effort intensity reductions (measured by oxygen uptake) of up to 12.6\% compared to normal walking, and up to 25.5\% compared to walking with the passive exoskeleton. Cardiodynamic response of HR, although delayed, proved sufficient for adaptation in most tasks, and delay-induced limitations primarily affected brief bouts of abrupt change in intensity. However, we found discernible patterns in HR shortly after the onset of such changes that can be exploited to improve responsiveness. Our findings underscore the potential of HR as a promising measure of user effort intensity, encouraging future research to explore its integration into advanced adaptive algorithms.

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Section: Introductionmentioning

confidence: 99%

Adaptive Hip Exoskeleton Control using Heart Rate Feedback Reduces Oxygen Cost during Ecological Locomotion

Manzoori,

Malatesta,

Mortier

et al. 2024

Preprint

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Novel neuromuscular controllers with simplified muscle model and enhanced reflex modulation: A comparative study in hip exoskeletons

Manzoori,

Messara,

Di Russo

et al. 2024

Wearable Technol.

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Neuromuscular controllers (NMCs) offer a promising approach to adaptive and task-invariant control of exoskeletons for walking assistance, leveraging the bioinspired models based on the peripheral nervous system. This article expands on our previous development of a novel structure for NMCs with modifications to the virtual muscle model and reflex modulation strategy. The modifications consist firstly of simplifications to the Hill-type virtual muscle model, resulting in a more straightforward formulation and reduced number of parameters; and second, using a finer division of gait subphases in the reflex modulation state machine, allowing for a higher degree of control over the shape of the assistive profile. Based on the proposed general structure, we present two controller variants for hip exoskeletons, with four- and five-state reflex modulations (NMC-4 and NMC-5). We used an iterative data-driven approach with two tuning stages (i.e., muscle parameters and reflex gains) to determine the controller parameters. Biological joint torque profiles and optimal torque profiles for metabolic cost reduction were used as references for the final tuning outcome. Experimental testing under various walking conditions demonstrated the capability of both variants for adapting to the locomotion task with minimal parameter adjustments, mostly in terms of timing. Furthermore, NMC-5 exhibited better alignment with biological and optimised torque profiles in terms of timing characteristics and relative magnitudes, resulting in less negative mechanical work. These findings firstly validate the adequacy of the simplified muscle model for assistive controllers, and demonstrate the utility of a more nuanced reflex modulation in improving the assistance quality.

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Task-agnostic exoskeleton control via biological joint moment estimation

Molinaro,

Scherpereel,

Schonhaut

et al. 2024

Nature

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Estimating human joint moments unifies exoskeleton control, reducing user effort

Cited by 19 publications

References 66 publications

Adaptive Hip Exoskeleton Control using Heart Rate Feedback Reduces Oxygen Cost during Ecological Locomotion

Adaptive Hip Exoskeleton Control using Heart Rate Feedback Reduces Oxygen Cost during Ecological Locomotion

Novel neuromuscular controllers with simplified muscle model and enhanced reflex modulation: A comparative study in hip exoskeletons

Task-agnostic exoskeleton control via biological joint moment estimation

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