Project Readiness Package Rev 5/22/12
Administrative Information:
· Project Name (tentative): / Active Ankle-Foot Orthotic: Untethered Non-Air Muscle· Project Number, if known:
· Preferred Start/End Quarter in Senior Design:
Fall/Winter 2012
· Faculty Champion:
Name / Dept. / Email / PhoneDr. Beth DeBartolo / ME / / 475-2152
· Other Support, if known:
Name / Dept. / Email / PhoneDr. Lamkin-Kennard / ME /
· Project “Guide” if known:
· Primary Customer, if known (name, phone, email):
Dr. Beth DeBartolo, 475-2152,
· Sponsor(s):
Name/Organization / Contact Info. / Type & Amount of Support CommittedRIT / TBD
Project Overview:
Foot drop, or the inability to dorsiflex the foot (i.e., point your toe upward) is a fairly common lasting side-effect of a stroke, affecting approximately 20% of stroke survivors (~1.3 million people each year). Foot drop 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. Many current AFOs, particularly those used by people who need significant foot support, are either rigid or constrain the user's motion in ways that force unnatural gait. Commercially available AFOs are only capable of pointing the user’s foot up when off the ground. These passive devices do not allow users to safely move down inclines or stairs as the user’s foot will always be pointed upwards when off of the ground.
The development of an active AFO that utilizes a terrain sensing system has been produced by an MS student, Christopher Sullivan. This project intends to use the terrain sensing system in order to accommodate the user’s foot to upcoming terrain. This device will utilize an integrated micro-controller to interpret terrain data and a torque device to rotate the user’s foot to the desired position throughout the gait cycle.
Detailed Project Description:
Beginning in the fall of 2012, there will be 2 senior design teams developing Active AFOs that utilize the terrain sensing system. The scope of the Active Ankle-Foot Orthotic: Tethered team will be to design an active AFO equipped with air muscles as a foot actuation device. Because air muscles require high amounts of energy to contract, the system will be tethered to an air supply. Electrical power, and a connection to a computer for data processing will also be provided via the tethering device. The value of developing a tethered system would be to rehabilitate stroke patients just after incidents in which case they need help learning how to walk with a foot drop condition.
The scope of this project, the Active Ankle-Foot Orthotic: Untethered Non-Air Muscle, will be to design an active AFO in parallel to that of the tethered system. In order to make the device usable all day, a different torque mechanism will be required other than air muscles. The AFO device will utilize an onboard micro-controller to interpret sensor data. A battery will be used to power the sensors, micro-controller, and torque device, if necessary. This device will be useful for users with foot drop to wear on a day to day basis.
Future projects include Active Ankle-Foot Orthotic: Air Muscle Un-Tethered. This device will incorporate an un-tethered air muscle powered system that utilizes the onboard control system. Air power will be provided by a compressed air tank stored on the AFO unit. The Active Ankle-Foot Orthotic: device will use a non-rigid, form fitting structure that rotates the foot in the most natural way.
Customer Needs and Objectives:
Safe / S1 / follow safety guidelines and standards
S2 / safe for daily operation
S3 / energy stored safely
S4 / no sharp protrusions
S5 / allergy conscious
Flat Terrain / FT1 / support regular gait cycle
FT2 / hold foot up when stepping forward
FT2 / range of motion to allow full dorsiflexion and plantar flexion
FT4 / resist foot slap
FT5 / operate smoothly/simulate normal muscle behavior
FT6 / allow for extended use without straining leg from weight
Portable / P1 / untethered
P2 / last for a full day without recharging/refueling
P3 / stay secure throughout the day
Comfortable / CF1 / tolerable to wear for full day use
CF2 / non-invasive
CF3 / secure foot in orthotic
CF4 / non-abrasive
CF5 / allow wide size range of users
CF6 / allow normal cooling of leg
CF7 / allow bending of knee
CF8 / allow toes to flex up
CF9 / keep toes from curling down
CF10 / aesthetically pleasing
CF11 / low noise
Durable / D1 / reliable for day to day usasge
D2 / sensors/controls withstand elements
D3 / usable in rain/shower
D4 / washable
Special Terrain / ST1 / allow natural movement up and down stairs and ramps
ST2 / adapt to different terrains
ST3 / fast system response between sensing and doing
ST4 / correctly interprets sensor information
ST5 / support foot drop over obstacles
Convenient / C1 / fit into normal shoe size
C2 / reduce time and cost of custom fitting process
C3 / easy to take off
C4 / easy patient interface with sensing system
C5 / easily adjustable
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Project Readiness Package Rev 5/22/12
· Functional Decomposition:
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Project Readiness Package Rev 5/22/12
· Engineering Specifications:
Engineering Specification Number / Engineering Specification Description / Units of Measure / Preferred Direction / Nominal Value / Method of Validation / Stems From Customer Needs1 / Torque on Foot / N-m / Up / ≥±1.5 / Test / FT1,2,4,ST1,5
s2 / System response time (sensing terrain to actuating device) / ms / down / <150 / Test / ST3
s3 / predicts step up / yes/no / - / yes / Test / ST1,2,4
s4 / predicts step down / yes/no / - / yes / Test / ST1,2,4
s5 / predict flat / yes/no / - / yes / Test / FT1,ST5
s6 / predicts ramp up / yes/no / - / yes / Test / ST1,2,4
s7 / predicts ramp down / yes/no / - / yes / Test / ST1,2,4
s8 / predicts speed of person / m/s / range / ±0.1 / Test / FT1,ST3
s9 / measure angle of foot / degrees / range / ±5 / Test / FT1,2,4,ST4
s10 / allowable range of motion between foot and shin / degrees / range / 94.5 to 137.7 / Test / FT1,3,CF8,9,ST1
s11 / follow safety standards / yes/no / - / - / S1,2,3
s12 / untethered usage time / steps / up / >3000 / Test / P1,2,D1
s13 / charging time from full discharge / hours / down / 8 / Test / S3,P1
s14 / fits calf (diameter) / mm / range / 292 to 433 / Measurement / CF1,3,5
s15 / fits foot (length) / mm / range / 212 to 317 / Measurement / CF1,3,5
s16 / Time to remove for patient TBD / seconds / down / 180 / survey user / C3
s17 / force to secure constraints / N / down / < 80 N / Test / C4
s18 / force to remove constraints / N / down / < 80 N / Test / C3
s19 / Force to remove device from foot when secured / N / up / > 2*AFO Weight / Test / P3,CF3
s20 / hours to fit / hours / down / ≤ 1 / - / C2
s21 / monitoring/display of energy level / yes/no / - / yes / - / D1,C5
s22 / error status / yes/no / - / yes / - / S2,D1,C5
s23 / radius of edges/corners on AFO / mm / up / 0.5 / - / S4,CF1,2
s24 / weight of entire device / kg / down / ≤3 / weigh / FT6
s25 / Harm to user (survey) / scale / down / - / survey user / S2,4,5,CF1,CF4
s26 / Noise Level (at ears of user) / dB / down / 60 / Test / CF11
s27 / Moving devices and electronics use standard dust and water shielding / yes/no / - / yes / - / D1,2,3,4
s28 / Operates in environment temperature range / °C / range / -17.8 to 37.8 / Component Ratings / D2
s29 / Overall comfort rating by some sample size / scale / up / - / survey user / CF1-11
s30 / Overall aesthetic rating by some sample size / scale / up / - / survey user / CF10
s31 / Minimum life until failure / steps / up / 5.5 million / *test / D1
s32 / Allowable toe extension/flexion / degrees / range / 0-50 / test / CF8, CF9
s33 / Fits with users regular shoe size / yes/no / - / yes / - / C1
*Minimum Life Until Failure: As part of the design and testing process teams should consider ways to prove an expected life as listed. Previous tests on the device or tests conducted on components in a similar application will be acceptable. Methods of superposition or extrapolation of high wear components may also be considered.
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Project Readiness Package Rev 5/22/12
· Constraints:
o System must utilize Christopher Sullivan’s terrain sensing system
o Safety constraints (see other information below)
o Device must accommodate a general range of population
§ 5th percentile females to 95th percentile males
o User must be able to wear his/her regular shoes while wearing device
o Device may not use air muscles as actuation device
o No part of the device shall extend above the knee joint
· Potential Concepts:
o Ratchet Device:
§ User’s foot rotates forward when stepping forward, becomes “locked” by ratchet, and is constrained from dropping while off of the ground. Prior to landing the ratchet “releases” the foot at the appropriate time and gravity pulls the foot downward.
o Disk Break
§ A disk brake, attached to the user’s ankle, could be turned on to restrict motion. The pressure on the disk plate would be reduced to control the rate at which the user’s foot is rotated downward by gravity
o Friction Disk Clutch
§ A friction disk clutch would be actuated to restrict motion. Actuation pressure is slowly released to control the rate at which the user’s foot is rotated downward by gravity.
o Servo Motor
§ A servomotor mounted on or behind the ankle could be used to apply the necessary torque to the foot either directly or through a gear and belt system.
§ This project would incorporate the use of the skills of an electrical engineer
· Project Deliverables:
1. A fully functional active AFO consisting of:
I. A device capable of applying torque to and rotating the user’s foot
II. Implemented circuit interfacing with the sensing system, microcontroller, and actuation device
III. A solid frame (may be purchased) that connects all portions of the device to the user including:
i. Energy storage medium
ii. Foot rotation device
iii. Terrain sensing system
iv. Microcontroller
2. Submission of design to the ASME Undergraduate Design Project Competition in Rehabilitation and Assistive Devices
· Budget Estimate:
$500
· Intellectual Property (IP) considerations:
· Other Information:
* All components of the finished product and test procedures must adhere to known safety regulations as appropriate:
§ Review by RIT Institutional Review Board (IRB)
§ ASME Boiler and Pressure Vessel Code
§ ISO TC168 - Prosthetics and Orthotics
§ IEEE C95.6-202: Safety Levels with Respect to Human Exposure to Electromagnetic Field
· Continuation Project Information:
Student Staffing:
· Anticipated Staffing Levels by Discipline:
Discipline / How Many? / Anticipated Skills NeededEE / 1 / EE1: Basic analog circuit design to include voltage and current sense circuitry, power budget analysis, battery selection, regulation circuitry, sensor interface circuitry. Implementation of electromechanical actuation equipment
ME / 2 / ME1: Analysis and design of the foot actuation device, including dynamics, power input/output, and testing
ME2: Machining and materials selection. Attachment of all components to solid frame and housing around electrical equipment. Management of user interface with frame. Materials selection.
CE / 1 / CE1: Digital Signal Processor/Microcontroller Unit selection, programming, algorithm implementation, memory allocation, board layout, DSP/MCU development board interface and usage
ISE / 1 / ISE1: Ergonomics (attachment & removal of device to user, wearability), usability and human interface, user calibration and customization
Other Resources Anticipated:
Faculty
Environment / MSD Design Center
Machine Shop & Brinkman lab
ISE Human Performance/Ergonomic Lab
Equipment / Terrain Sensing Hardware Components
Materials
Other / MS Thesis written by Christopher Sullivan
Terrain sensing algorithm (MatLab code)
Prepared by: / Shane Reardon / Date:
Appendix (PRP): Skills Checklist
Checklist Completed by (name): / Shane Reardon
For each discipline, indicate which skills or knowledge will be needed by students working on the associated project, and rank the skills in order of importance (1=highest priority). You may use the same number multiple times to indicate equal rank.
Mechanical Engineering
3D CAD / AerodynamicsMATLAB programming / CFD
3 / Machining (basic) / Biomaterials
1 / Stress analysis (2D) / Vibrations
1 / Statics/dynamic analysis (2D) / Combustion engines
Thermodynamics / GD&T (geometic dimensioning & tolerancing)
Fluid dynamics (CV) / Linear controls
3 / LabView (data acquisition, etc.) / Composites
Statistics / DFM
1 / Robotics (motion control)
FEA / Composites
Heat transfer / Other:
Modeling of electromechanical & fluid systems / Other:
2 / Fatigue & static failure criteria (DME) / 1 / Other: Materials Science
2 / Specifying machine elements
Reviewed by (ME faculty):
Industrial & Systems Engineering
Statistical analysis of data – regression / Shop floor IE – methods, time study2 / Materials science / Programming (C++)
Materials processing – machining lab
Facilities planning – layout, material handling / DOE
Production systems design – lean, process improvement / Systems design – product/process design
1 / Ergonomics – interface of people & equipment (procedures, training, maintenance) / Data analysis, data mining
Math modeling – linear programming), simulation / Manufacturing engr.
2 / Project management / DFx -- Manuf., environment, sustainability
Engineering economy – ROI / Other:
Quality tools – SPC / Other:
Production control – scheduling / Other:
Reviewed by (ISE faculty):
Electrical Engineering