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Wearable Essential Wearable Essential Tremor SolutionTremor
Solution
University of FloridaUniversity of FloridaBiomedical
EngineeringBiomedical Engineering
Jason Winters, Philip Jason Winters, Philip BarishBarish, Nikita
, Nikita AgarwalAgarwal, , Jennifer Jackson ,Ethan Sherman, Tang
TeJennifer Jackson ,Ethan Sherman, Tang Te
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What is Essential Tremor?What is Essential Tremor?
Common neurological disorderCommon neurological disorderShaking
of hands and headShaking of hands and headOccurs during intentional
movementsOccurs during intentional movementsCan affect almost any
part of the bodyCan affect almost any part of the body
Head, neck, torso, legs, tongue, voiceHead, neck, torso, legs,
tongue, voiceAffects 10 million Americans (mostly over Affects 10
million Americans (mostly over 60 years old)60 years old)Not linked
to other diseasesNot linked to other diseases
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Essential Tremor PatientEssential Tremor Patient
(click picture to watch video)
Patients drawings show improvement with medication
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EffectsEffects
Not debilitating, but is distressingNot debilitating, but is
distressingSocial embarrassmentSocial embarrassmentCan lead to
depressionCan lead to depressionEveryday tasks and those requiring
fine Everyday tasks and those requiring fine motor skills are
difficultmotor skills are difficult
Decrease in quality of lifeDecrease in quality of life
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Current SolutionsCurrent Solutions
Deep Brain Stimulation (Thalamus)Deep Brain Stimulation
(Thalamus)MedicationMedicationMechanical RestraintsMechanical
RestraintsModerate alcohol consumptionModerate alcohol
consumption
Neater Eater Bledsoe Arm Brace
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Project GoalProject Goal
Design a wearable device to mechanically Design a wearable
device to mechanically or electrically alter or minimize tremor.or
electrically alter or minimize tremor.
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Solutions ConsideredSolutions Considered
GyroscopesGyroscopesResistance bandsResistance bandsWorkstation
with fixed objectsWorkstation with fixed objectsActive servo
controlActive servo controlMuscle stimulationMuscle
stimulationMechanical DampingMechanical Damping
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Initial Design Initial Design Servo Assisted Servo Assisted
MovementMovement
ComputerComputer--controlled controlled feedback systemfeedback
systemResists high Resists high frequency tremor frequency tremor
motion motion Allows motion only Allows motion only under
persistent force under persistent force (low frequency)(low
frequency)Measures current Measures current needed to maintain
needed to maintain positionposition
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MaterialsMaterials
Hobby servo (Futaba S3003)Hobby servo (Futaba S3003)Servo
control board (NetMediaServo control board (NetMedias SRV8s
SRV8--T)T)Power sourcePower sourceVisual Basic programVisual Basic
programGraphical displayGraphical display
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System ComponentsSystem Components
Computer running visual basic control software
6Vbattery
servo control circuit
Futaba S3003 servo
RS-232 link
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Theory of OperationTheory of Operation
tremor
Intended motion
Reset condition
Intended motion timer triggered
Actual motion of servo & couple joint
Time (sec)A
ppro
xim
atio
n of
Tor
que
0 4.0
torque trigger threshold
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Drawbacks with DesignDrawbacks with Design
Relies on software to decide patients Relies on software to
decide patients intended movementsintended
movementsComplicatedComplicatedRequires power sourceRequires power
sourceNot waterproofNot waterproofDelicate mechanismDelicate
mechanism
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Final Design Final Design Viscous Damper DeviceViscous Damper
Device
Single DOF Single DOF mechanism allowing mechanism allowing
flexion/extension flexion/extension motion of wristmotion of
wristSuppresses high Suppresses high frequency tremor but frequency
tremor but permits slower permits slower movements using movements
using viscous dampingviscous dampingAttaches to forearm Attaches to
forearm and hand
(click picture to watch video)and hand
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System ComponentsSystem Componentslinkage dashpotsfinger loop
frame
elastic bandage
adjustable valve
finger loop rail hinge joint
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ConstructionConstruction
Frame made of 6061 Frame made of 6061 alumimunalumimun
alloyalloyElastic bandage attached to frame using Elastic bandage
attached to frame using 22--part epoxypart epoxy
Dashpots adapted from 10ml plastic Dashpots adapted from 10ml
plastic syringessyringes
Dashpot carriage held together with Dashpot carriage held
together with 22--part epoxypart epoxyWater used as viscous fluid
(dye added for Water used as viscous fluid (dye added for
visibility)visibility)
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Viscous DampeningViscous Dampening
Dissipates energy by Dissipates energy by restricting viscous
fluid restricting viscous fluid flow though small orificeflow
though small orificeDamping force is Damping force is proportional
to vibrating proportional to vibrating bodybody
F = cv
flow restricting orifice
velocity
damping force
viscous fluid
F = damping force
c = dampening coefficient
v = velocity of piston
(Piston in cylinder dashpot arrangement)
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Double dashpot designDouble dashpot design
Opposing dashpots Opposing dashpots attached to one attached to
one carriagecarriageDashpots function as Dashpots function as
reservoirs as wellreservoirs as wellOvercomes Overcomes suction
suction cavitationcavitation problem of problem of single dashpot
designsingle dashpot designConvenient place for Convenient place
for flow restriction valveflow restriction valve (click picture to
watch video)
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Essential Tremor SimulationsEssential Tremor Simulations
Mass
Simple massSimple mass--springspring--damper simulation damper
simulation shows influence of mechanical dampening shows influence
of mechanical dampening on tremor on tremor
spring (k)damper (c)
xF(t)
mx + cx + kx = F(t).. .
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Normal Movement SimulationNormal Movement Simulation
(click picture to watch video)
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Movement with Essential TremorMovement with Essential Tremor
(click picture to watch video)
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Essential Tremor Patient with DampingEssential Tremor Patient
with Damping
(click picture to watch video)
Slower movements but motion from tremor is suppressed.
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Attachment to BodyAttachment to Body
Elastic bandage with VelcroElastic bandage with Velcro provides
provides adjustable yet secure attachment to adjustable yet secure
attachment to forearm.forearm.Finger loop holds rail tight to back
of hand Finger loop holds rail tight to back of hand but allows
translation along length but allows translation along length
Needed since wrist joint and device hinge Needed since wrist
joint and device hinge joint arenjoint arent coincidentt
coincident
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General Device InformationGeneral Device Information
Minimum torque required to overcome Minimum torque required to
overcome mechanical friction = 0.37 Nmmechanical friction = 0.37
Nm
Equivalent to flexion of wrist while Equivalent to flexion of
wrist while gripping 1 pound weightgripping 1 pound weight
Total range of motion = 100 Total range of motion = 100 Flexion:
60Flexion: 60ExtentionExtention: 40: 40
Device weight = 10 ozDevice weight = 10 oz
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ValidationValidationtrial 1 (Hz) trial 2 (Hz) trial 3 (Hz)
Test 1 2.35 2.45 2.3Test 2 1 1.3 1.25Test 3 0.8 0.95 0.9
Duration = 20 secTest 1: no deviceTest 2: device on, stopcock
open fullTest 3: device on, stopcock mostly closed
Frequency
User was asked to cycle device as many times as possible in
given time.
Mean Frequency Comparison Between Different Tests
0
0.5
1
1.5
2
2.5
3
Test 1 Test 2 Test 3
Freq
uenc
y (H
z)
Mean
Damping constant has clear effect on motion suppression.
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AdvantagesAdvantages
Damping force adapts to tremor vibrationDamping force adapts to
tremor vibrationEasily adjustable damping constantEasily adjustable
damping constantRequires no power sourceRequires no power
sourceSimpleSimpleInexpensiveInexpensiveRobustRobust
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Design IssuesDesign Issues
Attachment to the bodyAttachment to the bodySlight play with the
hingeSlight play with the hingeLeaks possible under heavy
loadingLeaks possible under heavy loadingDifficult to attach to
body on oneDifficult to attach to body on ones owns ownPatient
testing neededPatient testing needed
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Future ImplementationFuture Implementation
Currently designed for wrist joint but can Currently designed
for wrist joint but can be applied to other hinge joints (i.e.
elbow)be applied to other hinge joints (i.e. elbow)
More joints need damping to greatly suppress More joints need
damping to greatly suppress tremortremor
High precision machining to reduce play in High precision
machining to reduce play in linkageslinkagesCustom molded cuffs for
easier Custom molded cuffs for easier attachment to bodyattachment
to bodyMore compact designMore compact design
Wearable Essential Tremor SolutionWhat is Essential
Tremor?Essential Tremor PatientEffectsCurrent SolutionsProject
GoalSolutions ConsideredInitial Design Servo Assisted
MovementMaterialsSystem ComponentsTheory of OperationDrawbacks with
DesignFinal Design Viscous Damper DeviceSystem
ComponentsConstructionViscous DampeningDouble dashpot
designEssential Tremor SimulationsNormal Movement
SimulationMovement with Essential TremorEssential Tremor Patient
with DampingAttachment to BodyGeneral Device
InformationValidationAdvantagesDesign IssuesFuture
Implementation