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SBC2013-14689: Un-Tethered, Active Ankle-Foot Orthotic. Rochester Institute of Technology Rochester, NY. The Team. Team Members: Pattie Schiotis – Team Manager (ME) Shane Reardon – Lead Engineer (ME) Dana Kjolner (EE) Robert Ellsworth (EE) Sam Hosig (CE) John Williams (CE) - PowerPoint PPT Presentation
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SBC2013-14689:Un-Tethered, Active Ankle-Foot Orthotic
Rochester Institute of TechnologyRochester, NY
Team Members:◦Pattie Schiotis – Team Manager (ME)◦Shane Reardon – Lead Engineer (ME)◦Dana Kjolner (EE)◦Robert Ellsworth (EE)◦Sam Hosig (CE)◦John Williams (CE)
•Faculty Guide: Dr. Elizabeth DeBartolo
The Team
Introduction Project Background Key Customer Needs System Architecture Component Breakdown
◦ Mechanical Locking System◦ Electronics Circuit and PCB◦ Sensors◦ Microcontroller
Testing Results Future Work Demo
Agenda
Inability to dorsiflex the foot due to loss of control of peroneal nerve
Lasting side effect of a stroke, affecting approximately 20% of stroke survivors◦ ~20 million people per year
Condition can also occur as a side effect of ALS (Lou Gherig's Disease), Multiple Sclerosis, or injury to the peroneal nerve, increasing the number of people affected
People with this condition have difficulty maintaining a proper gait cycle◦ “Foot crash”
Project Background: Foot Drop
Patients have adopted the use of ankle foot orthotics (AFOs) to aid with dorsi flexion
Market consists mostly of “passive” devices◦ Rigid braces which prevent unwanted plantar flexion. Foot is always pointed in
the upwards direction. These devices do not allow for safe maneuvering down stairs and
ramps The goal of this project is to design and develop an
“active” AFO which allows safe movement on flat surfaces as well as up and down stairs and ramps
Project Background: AFO Market
User will have no ability to either plantar-flex or dorsi-flex their foot
Side to side stability of the foot will be ignored
Worst case will be analyzed:◦ 95 percentile male having heavy foot.◦ Fast walker – gait cycle less than 1 second.
Device may not use air muscles as an actuation source
AFO Custom made for each client
Assumptions & Constraints
Key Customer NeedsPrimary Needs: Secondary Needs: Safety Portable
◦ Lasts all day without charging/refueling
◦ Lightweight◦ Tolerable to wear all day
Reliable Accommodates Flat Terrain Accommodates Special
Terrain◦ Stairs◦ Ramps◦ Obstacles
Comfortable◦ Aesthetically Pleasing
Durable◦ Water Resistant◦ Corrosion Resistant
Salt & Environment Biocompatibility
Convenient◦ Easy to put on and take
off
Key Engineering Specifications
Spec Number Engineering Specification Description Units of
MeasureNominal
Value
s1 Torque on Foot ft-lbf ±2
s2 System response time (sensing terrain to actuating device) ms <400
s4 predicts step down yes/no yess5 predict flat yes/no yess7 predicts ramp down yes/no yes
s10 allowable range of motion between foot and shin degrees 70 to 135
s12 untethered usage time hrs/steps 10 hrs/ 3000 steps
s17 force to secure constraints lbf < 18s18 force to remove constraints lbf < 18s23 radius of edges/corners on AFO in <0.02
s24 weight of entire device lbf ≤2.2
s28 Operates in environment temperature range °F 0-100
CAD modelSystem Architecture
Sensors
Piston/Cylinder
Mounting Bracket
Valve
Battery
Processor
Reservoir
Concept: Selectively prevent foot from plantar flexing while off the ground
Piston-cylinder arrangement attached posterior to heal and calf via 2 pin joints
Piston actuates within cylinder as dorsi & plantar flexion occurs
Mechanical Locking System
Mechanical Locking System
“Locked” Mode “Free” Mode Valve on top of the cylinder is
closed Water inside cylinder is
compressed by piston upon plantar-flexion
Motion of piston is therefore restricted, preventing plantar flexion
Valve is open Water is free to travel
between cylinder and reservoir upon actuation of piston
Allows for plantar and dorsi flexion
Electronic Circuit and Board Design
Charger ConnectorD 1
D 1N 4002
Micro Controller and SensorsM1
IR F 5 30
V 112V
VB SD 1 -S IP
6
24
VOU TVIN
GND
U 31 2
D 2
D 1N 40 02
C 1
10 0uF
R 2
10 k
C 2
10 0uF
Solenoid
LED
SD Card Switch
Connector
Utilize sensor system developed by MS student Christopher Sullivan
Vertical sensor determines if the foot is on or off ground
Forward sensors detects upcoming terrain
Sensors
Processing path of microcontroller
Microcontroller
Range of Motion◦ 70.03º-147.27º
Weight of Device◦ 2.42 lbs
Terrain prediction◦ Detects flat, descending stairs and ramps
System Response Time◦ Average ~300ms
Testing Results
Create smaller electronics box◦ Reduce weight, improve aesthetics, switch in correct
location Different battery
◦ Reduce size and weight, improve usage time Recommend using plastic fittings
◦ Weight reduction, corrosion resistance, could not find in store
SD card expansion board◦ Improve data collection
Human Trials with AFO that fits user◦ More accurate data collection
Areas of Improvement
Budget breakdown…
Economic Feasibility
Demonstration
Questions?