Reducing the energy cost of walking with low assistance levels through optimized hip flexion assistance from a soft exosuit
Open accessAbstract
As we age, humans see natural decreases in muscle force and power which leads to a slower, less efficient gait. Improving mobility for both healthy individuals and those with muscle impairments/weakness has been a goal for exoskeleton designers for decades. In this work, we discover that significant reductions in the energy cost required for walking can be achieved with almost 50% less mechanical power compared to the state of the art. This was achieved by leveraging human-in-the-loop optimization to understand the importance of individualized assistance for hip flexion, a relatively unexplored joint motion. Specifically, we show that a tethered hip flexion exosuit can reduce the metabolic rate of walking by up to 15.2 ± 2.6%, compared to locomotion with assistance turned off (equivalent to 14.8% reduction compared to not wearing the exosuit). This large metabolic reduction was achieved with surprisingly low assistance magnitudes (average of 89 N, ~ 24% of normal hip flexion torque). Furthermore, the ratio of metabolic reduction to the positive exosuit power delivered was 1.8 times higher than ratios previously found for hip extension and ankle plantarflexion. These findings motivated the design of a lightweight (2.31 kg) and portable hip flexion assisting exosuit, that demonstrated a 7.2 ± 2.9% metabolic reduction compared to walking without the exosuit. The high ratio of metabolic reduction to exosuit power measured in this study supports previous simulation findings and provides compelling evidence that hip flexion may be an efficient joint motion to target when considering how to create practical and lightweight wearable robots to support improved mobility.
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A tethered exosuit specifically designed to assist hip flexion can effectively lower the metabolic rate during walking by approximately 15.2 ± 2.6% compared to unassisted walking.
“The findings indicate that a tethered exosuit specifically designed to assist hip flexion can effectively lower the metabolic rate during walking by approximately 15.2 ± 2.6% when compared to unassisted walking.”
From Artificial intelligence enhanced sensors - enabling technologies to next-generation healthcare and biomedical platform (2023) · cites this paper as Kim et al. 2022
A soft and lightweight exosuit with human-in-the-loop optimization can significantly reduce energy expenditure associated with walking, achieving a nearly 50% decrease in mechanical power compared to existing state-of-the-art exosuits.
“By employing human-in-the-loop optimization, it was found the exosuit can significantly reduce the energy expenditure associated with walking, achieving a nearly 50% decrease in mechanical power compared to existing state-of-the-art exosuits.”
From Artificial intelligence enhanced sensors - enabling technologies to next-generation healthcare and biomedical platform (2023) · cites this paper as Kim et al. 2022
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- Authors
- Kim, J., Quinlivan, B. T., Deprey, L.-A., Arumukhom Revi, D., Eckert-Erdheim, A., Murphy, P., Orzel, D., & Walsh, C. J.
- Affiliations
- Harvard University (US)
- Corresponding author
- Walsh, Conor J.
- Venue
- Scientific Reports
- Published
- 2022-06-29
- Volume
- 12
- Issue
- 1
- Pages
- 11004-11004
- ISSN
- 2045-2322 (ISSN-L)
- PMC
- PMC9243082
- OpenAlex
- W4283752177
- Cited by
- 91
- References
- 58
- Citations by year
- 2026: 17 · 2025: 31 · 2024: 24 · 2023: 18 · 2022: 1
- FWCI
- 5.52
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Locations
- Scientific Reports (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Seoul National University Open Repository (Seoul National University) (submittedVersion)
- Funders
- - SAMSUNG Scholarship
- National Science Foundation (CMMI-1925085)
- U.S. Department of Health & Human Services | National Institutes of Health (NIH U01TR002775)
- - Wyss Institute for Biologically Inspired Engineering - John A. Paulson School of Engineering and Applied Sciences at Harvard University
- Topics
- Physical Sciences › Engineering › Biomedical Engineering › Prosthetics and Rehabilitation Robotics
- Physical Sciences › Engineering › Biomedical Engineering › Muscle activation and electromyography studies
- Physical Sciences › Engineering › Biomedical Engineering › Soft Robotics and Applications
- Keywords
- soft exosuit, wearable robotics, energy cost of walking, metabolic rate reduction, human-in-the-loop optimization, gait efficiency, muscle weakness
- MeSH terms
- Exoskeleton Device, Ankle, Biomechanical Phenomena, Gait, Humans, Paresis, Robotics, Walking
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