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Optimizing impedance control of an ankle exoskeleton to improve post-stroke walking mechanics and energetics

Award Number: F31HD097872
ORGANIZATION: NATIONAL INSTITUTE OF CHILD HEALTH AND HUMAN DEVELOPMENT
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: FELLOWSHIP/SCHOLARSHIP/STUDENT LOANS

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Project Summary Approximately 80% of the 7 million stroke survivors in the United States are affected by hemiparesis, or muscle weakness on one side of the body. When compared to unimpaired gait, hemiparetic walking is both asymmetric and slow. High interlimb asymmetry has been documented in ankle joint power output, and preferred walking speeds following a stroke range between <0.2 m/s and ~0.8 m/s compared to ~1.4 m/s in healthy adults. Alterations in gait characteristics following a stroke are associated with limitations in walking performance including altered loading on lower limb joints and increased metabolic cost. Changes in joint loading are associated with secondary diseases including osteoarthritis, lower-back pain, and due to reduced activity, cardiovascular disease. Additionally, increases in metabolic cost lead to rapid exhaustion, less activity and limited mobility. Interventions designed to reduce mechanical asymmetries may reduce metabolic cost and normalize joint loading for improved walking performance post stroke. Ankle exoskeletons have successfully reduced metabolic cost of walking in healthy controls and preliminary studies have demonstrated the potential of ankle exoskeletons to restore ankle function by applying ankle torque on the paretic limb. The long term goal of this research is to develop a robotic ankle exoskeleton that can improve walking performance post stroke to pave the way for a portable permanent walking aid. However, exoskeleton design for stroke is limited by a knowledge gap regarding the influence of exoskeleton assistance timing and magnitude on mechanical gait symmetry, metabolic cost, and joint contact loading. Understanding this relationship is critical because exoskeleton assistance provided at the wrong time, or of insufficient magnitude could be useless, or even detrimental to gait performance. We will use a combined experimental and computational approach to research the following aims: (1) Determine how the timing and magnitude of exoskeleton assistance influence the mechanical symmetry and metabolic energetics of post-stroke walking (2) Determine how timing and magnitude of exoskeleton assistance influences joint contact forces. We will use an exoskeleton emulator system to systematically vary exoskeleton assistance parameters (i.e. timing and magnitude) while directly evaluating user metabolic, kinematic, and kinetic response. Because we cannot easily measure joint contact forces in vivo, we will apply a computational simulation approach driven by the experimentally measured gait for each participant walking with exoskeleton assistance. This work will elucidate the how timing and magnitude of exoskeleton assistance impacts post-stroke walking asymmetry, metabolic cost and joint contact forces. Taken together, these aims provide new and essential information to enable the development of exoskeletons capable of minimizing comorbidities and restoring mobility to stroke survivors.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2023 ( Subtotal = -$24,663 )
2023	2021	NORTH CAROLINA STATE UNIVERSITY	2601 WOLF VILLAGE WAY	RALEIGH	NC	27695	WAKE	USA	Child Health and Human Development Extramural Research	001	3	11/23/2022	NON-COMPETING CONTINUATION	-$21,651
2023	2020	NORTH CAROLINA STATE UNIVERSITY	2601 WOLF VILLAGE WAY	RALEIGH	NC	27695	WAKE	USA	Child Health and Human Development Extramural Research	000	2	11/23/2022	NON-COMPETING CONTINUATION	-$3,012
														Subtotal = -$24,663

Issue Date FY: 2022 ( Subtotal = -$21,477 )
2022	2021	NORTH CAROLINA STATE UNIVERSITY	2601 WOLF VILLAGE WAY	RALEIGH	NC	27607	WAKE	USA	Child Health and Human Development Extramural Research	000	3	5/9/2022	NON-COMPETING CONTINUATION	-$21,477
														Subtotal = -$21,477

Issue Date FY: 2021 ( Subtotal = $43,128 )
2021	2021	NORTH CAROLINA STATE UNIVERSITY	2601 WOLF VILLAGE WAY	RALEIGH	NC	27607	WAKE	USA	Child Health and Human Development Extramural Research	000	3	3/16/2021	NON-COMPETING CONTINUATION	$43,128
														Subtotal = $43,128

Issue Date FY: 2020 ( Subtotal = $41,422 )
2020	2020	NORTH CAROLINA STATE UNIVERSITY	2701 SULLIVAN DR STE 240	RALEIGH	NC	27695	WAKE	USA	Child Health and Human Development Extramural Research	000	2	4/10/2020	NON-COMPETING CONTINUATION	$41,422
														Subtotal = $41,422

Issue Date FY: 2019 ( Subtotal = $39,836 )
2019	2019	NORTH CAROLINA STATE UNIVERSITY	2701 SULLIVAN DR STE 240	RALEIGH	NC	27695	WAKE	USA	Child Health and Human Development Extramural Research	001	1	2/15/2019	NEW	$0
2019	2019	NORTH CAROLINA STATE UNIVERSITY	2701 SULLIVAN DR STE 240	RALEIGH	NC	27695	WAKE	USA	Child Health and Human Development Extramural Research	000	1	2/15/2019	NEW	$39,836
														Subtotal = $39,836

Grand Total All Awards = $78,246

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Optimizing impedance control of an ankle exoskeleton to improve post-stroke walking mechanics and energetics

Award Number: F31HD097872

ORGANIZATION: NATIONAL INSTITUTE OF CHILD HEALTH AND HUMAN DEVELOPMENT

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: FELLOWSHIP/SCHOLARSHIP/STUDENT LOANS

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