Mechanics and energetics of post-stroke walking aided by a powered ankle exoskeleton with speed-adaptive myoelectric control

Journal of NeuroEngineering and Rehabilitation

Taylor J. M. Dick¹  Gregory S. Sawicki²  Tracy N. Giest³  Emily M. McCain³  Katherine R. Saul³  Michael D. Lewek⁴  Richard W. Nuckols⁵ 

[1] 0000 0000 9320 7537, grid.1003.2, School of Biomedical Sciences, University of Queensland, St. Lucia, QLD, Australia;0000 0001 2097 4943, grid.213917.f, Georgia Institute of Technology, Atlanta, GA, USA;0000 0001 2173 6074, grid.40803.3f, North Carolina State University, 911 Oval Drive, 27606, Raleigh, NC, USA;0000000122483208, grid.10698.36, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA;000000041936754X, grid.38142.3c, Harvard University, Cambridge, MA, USA;

关键词: Ankle mechanics;    Exoskeleton;    Trailing limb angle;    Propulsion;    Myoelectric control;    Electromyography;    Metabolic cost;    Hemiparesis;    Stroke rehabilitation;    Walking;   

DOI  :  10.1186/s12984-019-0523-y

来源: publisher

【 摘 要 】

BackgroundAnkle exoskeletons offer a promising opportunity to offset mechanical deficits after stroke by applying the needed torque at the paretic ankle. Because joint torque is related to gait speed, it is important to consider the user’s gait speed when determining the magnitude of assistive joint torque. We developed and tested a novel exoskeleton controller for delivering propulsive assistance which modulates exoskeleton torque magnitude based on both soleus muscle activity and walking speed. The purpose of this research is to assess the impact of the resulting exoskeleton assistance on post-stroke walking performance across a range of walking speeds.MethodsSix participants with stroke walked with and without assistance applied to a powered ankle exoskeleton on the paretic limb. Walking speed started at 60% of their comfortable overground speed and was increased each minute (n00, n01, n02, etc.). We measured lower limb joint and limb powers, metabolic cost of transport, paretic and non-paretic limb propulsion, and trailing limb angle.ResultsExoskeleton assistance increased with walking speed, verifying the speed-adaptive nature of the controller. Both paretic ankle joint power and total limb power increased significantly with exoskeleton assistance at six walking speeds (n00, n01, n02, n03, n04, n05). Despite these joint- and limb-level benefits associated with exoskeleton assistance, no subject averaged metabolic benefits were evident when compared to the unassisted condition. Both paretic trailing limb angle and integrated anterior paretic ground reaction forces were reduced with assistance applied as compared to no assistance at four speeds (n00, n01, n02, n03).ConclusionsOur results suggest that despite appropriate scaling of ankle assistance by the exoskeleton controller, suboptimal limb posture limited the conversion of exoskeleton assistance into forward propulsion. Future studies could include biofeedback or verbal cues to guide users into limb configurations that encourage the conversion of mechanical power at the ankle to forward propulsion.Trial registrationN/A.

【 授权许可】

CC BY