Advanced search
1 file | 557.37 KB

A simple exoskeleton that assists plantarflexion can reduce the metabolic cost of human walking

Philippe Malcolm (UGent) , Wim Derave (UGent) , Samuel Galle (UGent) and Dirk De Clercq (UGent)
(2013) PLOS ONE. 8(2).
Author
Organization
Abstract
BACKGROUND: Even though walking can be sustained for great distances, considerable energy is required for plantarflexion around the instant of opposite leg heel contact. Different groups attempted to reduce metabolic cost with exoskeletons but none could achieve a reduction beyond the level of walking without exoskeleton, possibly because there is no consensus on the optimal actuation timing. The main research question of our study was whether it is possible to obtain a higher reduction in metabolic cost by tuning the actuation timing. METHODOLOGY/PRINCIPAL FINDINGS: We measured metabolic cost by means of respiratory gas analysis. Test subjects walked with a simple pneumatic exoskeleton that assists plantarflexion with different actuation timings. We found that the exoskeleton can reduce metabolic cost by 0.18±0.06 W kg(-1) or 6±2% (standard error of the mean) (p = 0.019) below the cost of walking without exoskeleton if actuation starts just before opposite leg heel contact. CONCLUSIONS/SIGNIFICANCE: The optimum timing that we found concurs with the prediction from a mathematical model of walking. While the present exoskeleton was not ambulant, measurements of joint kinetics reveal that the required power could be recycled from knee extension deceleration work that occurs naturally during walking. This demonstrates that it is theoretically possible to build future ambulant exoskeletons that reduce metabolic cost, without power supply restrictions.
Keywords
LEVEL WALKING, MECHANICAL WORK, FOOT ORTHOSIS, OLDER-ADULTS, BIOMECHANICS, LOCOMOTION, ENERGETICS, MASS, POWERED ANKLE EXOSKELETONS, ENERGY-EXPENDITURE

Downloads

  • malcolm a simple exoskeleton.pdf
    • full text
    • |
    • open access
    • |
    • PDF
    • |
    • 557.37 KB

Citation

Please use this url to cite or link to this publication:

Chicago
Malcolm, Philippe, Wim Derave, Samuel Galle, and Dirk De Clercq. 2013. “A Simple Exoskeleton That Assists Plantarflexion Can Reduce the Metabolic Cost of Human Walking.” Plos One 8 (2).
APA
Malcolm, P., Derave, W., Galle, S., & De Clercq, D. (2013). A simple exoskeleton that assists plantarflexion can reduce the metabolic cost of human walking. PLOS ONE, 8(2).
Vancouver
1.
Malcolm P, Derave W, Galle S, De Clercq D. A simple exoskeleton that assists plantarflexion can reduce the metabolic cost of human walking. PLOS ONE. 2013;8(2).
MLA
Malcolm, Philippe, Wim Derave, Samuel Galle, et al. “A Simple Exoskeleton That Assists Plantarflexion Can Reduce the Metabolic Cost of Human Walking.” PLOS ONE 8.2 (2013): n. pag. Print.
@article{3136511,
  abstract     = {BACKGROUND: Even though walking can be sustained for great distances, considerable energy is required for plantarflexion around the instant of opposite leg heel contact. Different groups attempted to reduce metabolic cost with exoskeletons but none could achieve a reduction beyond the level of walking without exoskeleton, possibly because there is no consensus on the optimal actuation timing. The main research question of our study was whether it is possible to obtain a higher reduction in metabolic cost by tuning the actuation timing.
METHODOLOGY/PRINCIPAL FINDINGS: We measured metabolic cost by means of respiratory gas analysis. Test subjects walked with a simple pneumatic exoskeleton that assists plantarflexion with different actuation timings. We found that the exoskeleton can reduce metabolic cost by 0.18{\textpm}0.06 W kg(-1) or 6{\textpm}2\% (standard error of the mean) (p\ensuremath{\mkern1mu}=\ensuremath{\mkern1mu}0.019) below the cost of walking without exoskeleton if actuation starts just before opposite leg heel contact.
CONCLUSIONS/SIGNIFICANCE: The optimum timing that we found concurs with the prediction from a mathematical model of walking. While the present exoskeleton was not ambulant, measurements of joint kinetics reveal that the required power could be recycled from knee extension deceleration work that occurs naturally during walking. This demonstrates that it is theoretically possible to build future ambulant exoskeletons that reduce metabolic cost, without power supply restrictions.},
  articleno    = {e56137},
  author       = {Malcolm, Philippe and Derave, Wim and Galle, Samuel and De Clercq, Dirk},
  issn         = {1932-6203},
  journal      = {PLOS ONE},
  language     = {eng},
  number       = {2},
  pages        = {7},
  title        = {A simple exoskeleton that assists plantarflexion can reduce the metabolic cost of human walking},
  url          = {http://dx.doi.org/10.1371/journal.pone.0056137},
  volume       = {8},
  year         = {2013},
}

Altmetric
View in Altmetric
Web of Science
Times cited: