Effect of timing of hip extension assistance during loaded walking with a soft exosuitReportar como inadecuado




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Journal of NeuroEngineering and Rehabilitation

, 13:87

First Online: 03 October 2016Received: 03 March 2016Accepted: 27 September 2016

Abstract

BackgroundRecent advances in wearable robotic devices have demonstrated the ability to reduce the metabolic cost of walking by assisting the ankle joint. To achieve greater gains in the future it will be important to determine optimal actuation parameters and explore the effect of assisting other joints. The aim of the present work is to investigate how the timing of hip extension assistance affects the positive mechanical power delivered by an exosuit and its effect on biological joint power and metabolic cost during loaded walking. In this study, we evaluated 4 different hip assistive profiles with different actuation timings: early-start-early-peak ESEP, early-start-late-peak ESLP, late-start-early-peak LSEP, late-start-late-peak LSLP.

MethodsEight healthy participants walked on a treadmill at a constant speed of 1.5 m · s while carrying a 23 kg backpack load. We tested five different conditions: four with the assistive profiles described above and one unpowered condition where no assistance was provided. We evaluated participants’ lower limb kinetics, kinematics, metabolic cost and muscle activation.

ResultsThe variation of timing in the hip extension assistance resulted in a different amount of mechanical power delivered to the wearer across conditions; with the ESLP condition providing a significantly higher amount of positive mechanical power 0.219 ± 0.006 W · kg with respect to the other powered conditions. Biological joint power was significantly reduced at the hip ESEP and ESLP and at the knee ESEP, ESLP and LSEP with respect to the unpowered condition. Further, all assistive profiles significantly reduced the metabolic cost of walking compared to the unpowered condition by 5.7 ± 1.5 %, 8.5 ± 0.9 %, 6.3 ± 1.4 % and 7.1 ± 1.9 % mean ± SE for ESEP, ESLP, LSEP, LSLP, respectively.

ConclusionsThe highest positive mechanical power delivered by the soft exosuit was reported in the ESLP condition, which showed also a significant reduction in both biological hip and knee joint power. Further, the ESLP condition had the highest average metabolic reduction among the powered conditions. Future work on autonomous hip exoskeletons may incorporate these considerations when designing effective control strategies.

AbbreviationsANOVAAnalysis of variance

BFBiceps femoris

EMGElectromyographic

ESEPEarly-start-early-peak

ESLPEarly-start-late-peak

GMGluteus maximum

GRFsGround reaction forces

IMUInertial measurement unit

LSEPLate-start-early-peak

LSLPLate-start-late-peak

MGMedial gastrocnemius

RFRectus femoris

RMSRoot mean square

SEMStandard error of the mean

SOLSoleus

VMVastus medialis

Electronic supplementary materialThe online version of this article doi:10.1186-s12984-016-0196-8 contains supplementary material, which is available to authorized users.

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Autor: Ye Ding - Fausto A. Panizzolo - Christopher Siviy - Philippe Malcolm - Ignacio Galiana - Kenneth G. Holt - Conor J. Wals

Fuente: https://link.springer.com/article/10.1186/s12984-016-0196-8







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