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Design of an Energy Storing Orthosis for Providing Gait to People with Spinal Cord Injury Kyle Boughner May 20, 2014

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Project overview ESO concept Previous ESO device Project objective ESO design ESO evaluation ESO next steps Conclusion 2 Agenda

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Project Overview Spinal Cord Injury (SCI) Damage to any part of the spinal cord or nerves at the end of the spinal canal [1] Often causes permanent changes in strength, sensation and other body functions below the site of the injury Incidence in U.S. [2] 40 cases/million 12,000 new cases each year Prevalence in U.S. 270,000 people with SCI in 2012 Severity Quadriplegia Paraplegia Need 51% of SCI subjects identified gait restoration as a first choice in technology application [3] Physical and psychological health benefits [4] http://spinalstenosis.org [1] Mayo Clinic [2] NSCISC 2012 [3] Brown-Triolo et al. 2002 [4] Axelson et al. 1987 3

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4 Powered orthosis [2] Passive orthosis [1] Functional electrical stimulation (FES) Hybrid orthotic systems [3] [1] http://www.aodmobility.com/home/ [2] Vanderbilt University [3] Goldfarb et al. 2003 Project Overview: Gait Restoration Technologies

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Energy storage orthosis (ESO) Single channel FES Stimulation of quadriceps 53 Nm of quadriceps torque available [1] Four phases of gait: Leg kinematics [2],[3] Joint gravity torque Joint range of motion 5 ESO Concept Gait sequence [1] Hausdorff et al. 1991 [2] Biomechanics and Motor Control of Human Movement [3] Drillis et al. 1964

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Previous ESO Device 1 st generation [1] Gas spring and pneumatic energy storage Energy storage systems Leg model testing 2 nd generation [2] Joint locking Elastomer energy storing elements 2 nd generation continued [3] Energy element mounting location study Device issues Energy storing elements Packaging Sitting Donning and doffing device 6 2 nd generation ESO 2 nd generation knee joint 2 nd generation hip joint [1] Rivard et al. 2004 [2] Kangude et al. 2009 [3] Kangude et al. 2010 2 nd generation ESO

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ESO mechanical components ESO thigh concept ESO mechanical components Energy storing elements: Knee equilibrium Hip equilibrium Hip extension transfer Joint locking All located on thigh (bracing above and below) Design requirements 7 Project Objective: Design and Assess ESO Thigh Concept No. ESO Design Specifications MetricUnitValue 1Lateral widthm31 4 Equilibrium torque hip Equilibrium torque knee Nm >7.5 >8.2 5Thigh segment weightkg

Prototype design requirements Met by ESO bench-top prototype and computer solid model Static joint torque Energy storing springs can hold hip and knee joints are any angle in joint range of motion Higher torque than expected towards extension slower knee extension time than predicted 14 ESO Evaluation: Design and Static Torque Results No. ESO Design Specifications MetricUnitRequiredMeasured 1Lateral widthm3140 4 Equilibrium torque hip Equilibrium torque knee Nm >7.5 >8.2 20 16 5Thigh segment weightkg