Terrain Detection System for Foot Drop

PowerPoint Presentation

Terrain Detection System for Foot DropChristopher R. SullivanMechanical EngineeringApril 18th, 2012Advisor: Elizabeth A. DeBartolo, Ph.D.

Name, department, event, date, advisorGait Cycle and Foot DropImage Source: http://sports.jrank.org/article_images/sports.jrank.org/dorsiflexion.1.jpg100%Foot StrikeOpposite Toe-OffOpposite Foot StrikeToe-OffFoot ClearanceTibia VerticalFoot StrikePeriodsInitial Double-Limb SupportSingle-Limb StanceSecond Double-Limb SupportInitial SwingMid-SwingTerminal SwingStanceSwing% of Cycle0%62%PeriodsInitial SwingMid-SwingTerminal SwingToe-OffSwing% of Cycle62%100%Mid TripFoot CrashFallenFoot Drop is characterized by Inability to control the foot during the Gait CycleStrokeCerebral PalsyDirect injury to the Peroneal Nerve

2What is an Ankle Foot Orthotic?Replace lost ankle functionalityFoot dropCorrect brace for the correct problem

Image Source: http://www.mobilelimbandbrace.com/images/Articulating_AFO_Overlap.gifhttp://www.spsco.com/assets/images/dynamic-walk-single-side-2_large.jpghttp://proactiveasia.com/web_image/orthotics/Trulife%20semi-solid-afo_web.gif

Jointed BraceDynamic Walk

Solid BraceCurrently aofs are the leading for of brace for combating foot drop. The work by limiting the maximum plantar flexion that a patients foot can achievePateints and AFOs varry widly based on the sivarity of a patients disability, foot drop can be compounded with toe currling and rolling of the ankle, all of which would require a studiur braceThe problem with this is there are times when allowing more flexsion of the ankle is actually benificial to the patient, such as when someone is walking down a ramp of down a set of stairs.

3Project GoalCreate an Ankle mounted system for identifying specific ground conditionsTodays talkNeeds assessment Data Collection TechniquesPreliminary Results

Image Source: http://transit-safety.volpe.dot.gov/publications/safety/pedestrian/html/images/dot-tsc-umta-84-36_p0009a.gifMy goal is to create a system to recgnize these changes in ground condisions. It should be contained within the AFO, which means it must be mounted to the ankel. In todays talk we will go over just how this problem was discovered, and steps that I have taken in solving the problem

PER-A-Nee-il

4Stakeholder InterviewsInterviewed Clients, Clinicians,and Prosthetist OrthotistMajor takeawaysFoot drop has many other compound symptomsProsAllow clients to walkConsweight/bulk of the AFOInstability on ramps and stairsAFO users needs can differ widely

Image Source: http://www.humanresourcesdegree.net/images/stories/School%20Logos%20-%20Masters/NazarethCollege.jpg http://www.workforcediversitynetwork.com/images/logos/RGHS_stacked_150.jpghttp://www.rochesterorthopedic.com/

The very first thing I did was to complete patient interveiws, to determin if there was any problem that they all seemed to face.It is important to keep in mind the wide vareations within the pateint population, yet they all seem to feel instability while walking down stairs and ramps.This is because as I have stated earlier their brace is hindering them from making a proper contact with the ground.All of the patients complained about the instability they felt on stairs

Explain why they feel uncomfortable !!!!!!!!!Rochester orthopedic PEDIC LABS

Peoples needs vary widely!Distance Detected Level Ground vs. Descending Stairs

Feasibility talk about using gait data from other studies to generate simulations of what a distance sensor would need to seeInfra red range finders

Detectable differences

6IR Range FinderRange Finder Selected GP2Y0A02Yk Image Source: http://www.technologicalarts.com/myfiles/data/gp2d120.pdf

1.5 4 8 12 24 31.5 40 59.5 216.5MaximumRangeMinimumRange

Walking Up Stairs Raw Distance Sensor VoltageReplace technical drawing with chart from next page showing rangeRANSACRANdom SAmple ConsensusStarting AssumptionsInliersFit to a modelOutlinersCan come from noisy data, or erroneous assumptions

Image Source: http://en.wikipedia.org/wiki/RANSACRANSACInput:DataMinimum number of data pointsAdded guess at the gait periodNumber of iterationsMinimum errorMinimum number of points for a real modelOutput:Best model Best consensus set Best errorDetermining Gait PeriodPiezoelectric plateIdentifying the proper gait periodPick two similar high point and test the rest of the data for similaritiesDifferentiation between direction change and heel strike

Level Walking Gait Period AnalysisWhen the results are not so pretty

Down Stairs Gait Period AnalysisRANSACModel to be fit Fourth Order Fourier seriesAdaptationPicking the correct repeating curveChecking the rest of the data

Level Walking RANSAC fitRANSAC Results

Next StepsFinding better determination of foot ground collision.Filtering out of erroneous models given from noisy data.Using new ground collision data to enhance existing predictive program.Find determination of when a patient is not walking.Put all of this onto a microcontrollerFuture ApplicationIntegrating system into an AFOAdding functionality of tracking long term change of patients gait characteristics.

AcknowledgmentsFunding was supplied by the RGHS RIT alliance Seed fundRochester General HospitalRichard L Barbano, MD, Ph.D., FAANAdvisorElizabeth A. DeBartolo, Ph.D.Thesis Committee Mario Gomes, Ph.D.Kathleen Lamkin-Kennard, Ph.D.Nazareth College Physical Therapy ClinicJ.J. Mowder-Tinney PT, PhD, NCSRochester Orthopedic LabsShawn Biehler, CPO

Questions?

LaGrange's MethodProposed DesignAttaches to the back of existing AFOLinear actuator shifts carriage to either side Carriage holds two individually adjustable backstops The actuator doesnt have to support the footInfrared range finderDetect terrain

Include detailed schematic only of final proposed designIssues with DesignIt adds weightMake the Brace LighterAttaching to the back of an existing AFOAdhesiveVacuumUse existing backstopVelcroActuationPiezoelectric Linear actuatorKnowing the GroundAccelerometerIR Range Finder

Remove, or keep as backupAccelerometersRequire a lot of data analysisDrift in integration accuracy Measuring many different thingsMost of which I am uninterested inMost of which is very noise

Same, or remove if youre not going this routeMulti Surface Sensing Ankle Foot OrthoticFunctional Block DiagramPowerGround ProfileGround Identification SensorMicro-ControllerPositionActuatorRange of MotionIfStairs or RampLevel GroundInputs out putsFit the 3 slids you are missing into this oneTalk about separating out these different criteria into ways to generate more designs23Customer NeedsFits into a shoeEase of accessAdjustabilityLight weightPortableInexpensiveAble to be used on both sides of the bodySafetyDurability/fatigue lifeBiocompatible surfaceAble to be cleaned/sterilizedFunctionalityProvide appropriate support for the foot at the appropriate timeStairs RampLevel surfaceProvide accurate assessment of ground conditions, before the foot hits the ground.

These are just a few quick customer needs that I have defined for the overall project. This includes work that will be done by a senior design team to actually building an afo to take advantage of my system.24Defining the Target ClientsThey should be able to supply feedbackWould not be a candidate for a commercially available AFOMust use a jointed brace I intend to test this device on people and they are going to need to be able to communicate back with me about if they 25ConstraintsMetricUnitsTestImportance (1-7)Fits into a shoeBinaryAttempt to fit into a shoe possibly using a floppy (find a better word) foot2Ease of access10 MinAttempt to put on with one hand, time results document relative range of motion necessary to complete task3AdjustabilitycmWhat rand of body types can this AFO fit?5Light weight