Multi Surface Sensing Ankle Foot Orthotic for Foot

Multi Surface Sensing Ankle Foot Orthotic for Foot Drop Christopher R. Sullivan Mechanical Engineering Student Research & innovation Symposium August 12 th, 2011 Advisor: Elizabeth A. De. Bartolo, Ph. D.

Gait Cycle and Foot Drop Stance Initial Double. Limb Support Angle (Deg) Periods 10 5 0 -5 -10 -15 -20 Terminal Swing Mid. Swing Initial Swing Ankle Angle Data % of Cycle Swing Second Double. Limb Support Single. Limb Stance Opposite Toe-Off Foot Strike Opposite Foot Strike Toe-Off Foot Clearance Foot Strike Tibia Vertical 62% 0% Swing Periods Initial Swing Mid. Swing 100% Terminal Swing Toe-Off % of Cycle Foot Crash Mid Trip 62% Image Source: http: //sports. jrank. org/article_images/sports. jrank. org/dorsiflexion. 1. jpg Fallen 100%

What is an Ankle Foot Orthotic? • Replace lost ankle functionality • Foot drop • Correct brace for the correct problem Dynamic Walk Jointed Brace Solid Brace Image Source: http: //www. mobilelimbandbrace. com/images/Articulating_AFO_Overlap. gif http: //www. spsco. com/assets/images/dynamic-walk-single-side-2_large. jpg http: //proactiveasia. com/web_image/orthotics/Trulife%20 semi-solid-afo_web. gif

Project Goal • Create an Ankle Foot Orthotic (AFO) that adapts to differing terrain to provide the correct amount of support • Todays talk • • Stakeholder interviews Needs assessment Preliminary design Preliminary analysis Image Source: http: //transit-safety. volpe. dot. gov/publications/safety/pedestrian/html/images/dot-tsc-umta-84 -36_p 0009 a. gif

Stakeholder Interviews • Interviewed Clients, Clinicians, and Prosthetist Orthotist • Major takeaways • Foot drop has many other compound symptoms • Pros • Allow clients to walk • Cons • weight/bulk of the AFO • Instability on ramps and stairs • AFO user’s needs can differ widely Image Source: http: //www. humanresourcesdegree. net/images/stories/School%20 Logos%20 -%20 Masters/Nazareth. College. jpg http: //www. workforcediversitynetwork. com/images/logos/RGHS_stacked_150. jpg http: //www. rochesterorthopedic. com/

Defining the Target Clients • They should be able to supply feedback • Would not be a candidate for a commercially available AFO • Must use a jointed brace

Customer Needs • • Fits into a shoe Ease of access Adjustability Light weight Portable Inexpensive Able to be used on both sides of the body Safety • Durability/fatigue life • Biocompatible surface • Able to be cleaned/sterilized • Functionality • Provide appropriate support for the foot at the appropriate time • Stairs • Ramp • Level surface

Functional Block Diagram Multi Surface Sensing Ankle Foot Orthotic Micro-Controller Ground Profile If Ground Identification Sensor Level Ground Position Power Actuator Stairs or Ramp Range of Motion

Proposed Design • Attaches to the back of existing AFO • Linear actuator shifts carriage to either side • Carriage holds two individually adjustable backstops • The actuator doesn’t have to support the foot • Infrared range finder • Detect terrain

Distance Detected Level Ground vs. Descending Stairs 0. 9 0. 8 Distance (m) 0. 7 0. 6 Level 0. 5 Stairs 0. 4 0. 3 Ramp 0. 2 0. 1 0 0% 10% 20% Gait % 30% 40% 50%

Moment about the Ankle During Swing 3. 0 θ 3 2. 5 m 3 Moment (Nm) 2. 0 1. 5 θ 2 θ 4 Moment Swing (Nm. . . 1. 0 m 2 m 4 0. 5 m 1 m 5 θ 5 0. 0 50% -0. 5 60% 70% 80% Gait % 90% 100% θ 1 x

Next Steps • • Device attachment to brace Find Ramp Gait Data Select and test Range Finder Select and test Actuator Define algorithm for determining floor surface Model Design Build and test

Acknowledgments Funding was supplied by the RGHS RIT alliance Seed fund Rochester General Hospital Richard L Barbano, MD, Ph. D. , FAAN Advisor Elizabeth A. De. Bartolo, Ph. D. Thesis Committee Mario Gomes, Ph. D. Kathleen Lamkin-Kennard, Ph. D. Nazareth College Physical Therapy Clinic J. J. Mowder-Tinney PT, Ph. D, NCS Rochester Orthopedic Labs Shawn Biehler, CPO

Questions?

La. Grange's Method •

Constraints Metric Units Fits into a shoe Binary Ease of access 10 Min Adjustability cm Light weight Portable Inexpensive Able to be used on both sides of the body <1 kg 10 hr <1000$ Binary Test Attempt to fit into a shoe possibly using a floppy (find a better word) foot Attempt to put on with one hand, time results document relative range of motion necessary to complete task What rand of body types can this AFO fit? Use hard plastic AFO as benchmark for weight Operation length BOM Can it be used on both sides of the body? Importance (1 -7) 2 3 5 4 1 6 7

Brainstorming Straps Comments Power Comments Passive Elements Comments Velcro Cheap, has a short lifespan, trouble getting proper contact Li-ion High Energy Density, 1200 cycles PEEK rods Flexible polymer Rods Plastic ratchet Relatively more expensive longer life time, solid connection Ni. H 2 lower energy density, 20000 Carbon Fiber cycles Special Sock Similar to amputee patients Passive Run until material Failure Rotary Dampers Geometry based on geometry the brace holds itself onto the patient Pressurized air Pressurizing air on demand would require a battery Metal Springs Knee brace uses the knee as an anchor hold the brace on the leg Mechanical wound To run like a clock (not a very likely choice) Bushing tilt Joint Half of a skate board Truck Active Elements Comments Sensors Comments Microcontrollers Comments Linear Actuator Bulky ADXL 345 Accelerometers are hard to use, drift Arduino Some are rather Large, but it has a good development community Electric Motor Piezoelectric Linear Actuator Requires gear box Sharp IR Range Finder No drift, but could hit pants Teensy Small same kind of Dev. Community as Arduino Seeeduino Smaller Arduino bigger than the Teensy Stepper motor Variable Rotary Dampers Easy location Hard to find Hold position at zero power Can be used for a leaf Spring

Solution Combinations Design # 1 2 Name Add on? Brace Material Carbon Variable PEEK rod AFO no Fiber Adjustable Plantar Stop add -on Yes none 4 Variable PEEK rod AFO With Carbon no Fiber Geo Fit Carbon N/A no Fiber 5 Rotary Damper AFO yes none 6 Variable Rotary Damper AFO 7 Stripper Motors AFO Polyethyle no ne Carbon no Fiber 8 Vareable Carbon Fiber Leaf Spring AFO Carbon no Fiber 3 Design 1 Variable peek Rod Straps Power Passive Elements Active Elements Comments Velcro LI-ion Peek rods Piezoelectric Linear Actuator Pulls Peek rod into it changing Spring initial Loading Li-ion Metal Springs Linear Actuator Changes the location on the Back Stop Piezoelectric Linear Actuator Pulls Peek rod into it changing Spring initial Loading Uses Geometry of Spring to Hold leg in place Geometry Li-ion Peek rods Velcro LI-ion Bushing Tilt Joint Linear Actuator Has a variable axis Moved by linear actuator Li-ion Rotary Dampers Rotary damper added on though a variable transmission, dampening used to stop foot Variable Rotary damper Velcro LI-ion Torsion Spring Stepper Motor Velcro LI-ion Carbon Fiber Linear Actuator change damping to stop foot when needed should be paired with a way to move the foot Holds the foot in position at proper time Carbon Fiber used as leaf spring in back of AFO with movable interfering piece, much like prostatic foot design, but variable Design 3 Variable peek Rod Geo Fit

Initial Design Matrix Criteria Fits into a shoe Ease of access Adjustability of overall foot position Variable axis Portable battery life/ battery dead? Inexpensive Feasibility (back stop change is base line) Level Surface Can Be adjusted to Stairs Can Be adjusted to Ramps Safety features? Durability Able to be cleaned Total + Total Sum 1 + 0 2 0 0 3 + + 4 0 5 0 6 0 7 0 8 + 0 + + - - - + 0 - - - - 0 - - - - + + 0 6 5 1 + + + 0 5 3 2 + + + 0 7 5 2 0 + + 4 7 -3 0 + + 0 2 7 -5 0 + + 3 8 -5 + + + 4 8 -4 + + + 0 6 5 1 0 0 0 1 0 1 Design # Name 1 Variable PEEK rod AFO 2 Adjustable Plantar Stop add-on 3 Variable PEEK rod AFO With Geo Fit 8 Vareable Carbon Fiber Leaf Spring AFO Concerns LEG actuators can take different actuation rods Linear actuator to hold plantar stop Is geo fit possible? And can it be used on all kinds of patients Look into complete mechanically driven brace, i. e. no control system AFO 0 0

IR Range Finder • Feasibility • Look into expected data 1. 5” 4” 8” 12” 24” 31. 5” 40” 59. 5” 216. 5” Figure 9. Sharp IR sensors Maximum Range Minimum Range Figure 10. Sharp IR sensors Distance Illustration Source: http: //www. technologicalarts. com/myfiles/data/gp 2 d 120. pdf

Issues with Design • It adds weight • Make the Brace Lighter • Attaching to the back of an existing AFO • Adhesive • Vacuum • Use existing backstop • Velcro • Actuation • Piezoelectric Linear actuator • Knowing the Ground • Accelerometer • IR Range Finder

Accelerometers • Require a lot of data analysis • Drift in integration accuracy • Measuring many different things • Most of which I am uninterested in • Most of which is very noise

Carbon Fiber Brace • Breaks the project up into 2 areas • Bulk reduction in weight and size will help get patients excited about their brace • Spring properties of carbon fiber Figure 7. Carbon Fiber