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
Introduction Project Background Key Customer Needs System Architecture Component Breakdown ◦ Mechanical Locking System ◦ Electronics Circuit and PCB ◦ Sensors ◦ Microcontroller Testing Results Future Work Demo
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”
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
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
Primary 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
Spec Number Engineering Specification Description Units of Measure Nominal Value s1Torque on Footft-lbf±2 s2 System response time (sensing terrain to actuating device) ms<400 s4predicts step downyes/noyes s5predict flatyes/noyes s7predicts ramp downyes/noyes s10 allowable range of motion between foot and shin degrees70 to 135 s12untethered usage timehrs/steps 10 hrs/ 3000 steps s17force to secure constraintslbf< 18 s18force to remove constraintslbf< 18 s23radius of edges/corners on AFOin<0.02 s24weight of entire devicelbf≤2.2 s28 Operates in environment temperature range °F0-100
CAD model 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
“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
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
Processing path of microcontroller
Range of Motion ◦ 70.03º º Weight of Device ◦ 2.42 lbs Terrain prediction ◦ Detects flat, descending stairs and ramps System Response Time ◦ Average ~300ms
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
Budget breakdown…
Demonstration