Administrative Information

Administrative Information

Project Readiness PackageRev 5/18/12

Administrative Information:

  • Project Name (tentative): Active Ankle Foot Orthotic: Untethered Flexible Exoskeleton Air Muscle
  • Project Number: ______
  • Preferred Start/End Semester in Senior Design: Fall 2014-1/Spring 2014-2
  • Faculty Champion:

Name / Dept. / Email / Phone
Dr. Beth DeBartolo / ME / / 475-2152
  • Other Support:

Name / Dept. / Email / Phone
Dr. Lamkin-Kennard / ME /
  • Project “Guide” if known: ______
  • Primary Customer (name, phone, email): Dr. Beth DeBartolo (ME), 475-2152,
  • Sponsor(s): ______

Name/Organization / Contact Info. / Type & Amount of Support Committed

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 ankle foot orthotics (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. In instances, particularly walking down ramps, the rigid AFO can cause a feeling of instability to the user. In order to address this problem, your team is charged with creating an active ankle foot orthotic for people suffering from foot drop.

The development of 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:

During 2012-13 and 2013-14 the groundwork for developing a portable active ankle foot orthotic will have been completed with the proof-of-concept portable air muscle-driven AFO. The work of prior teams is all available to you on EDGE and may contain valuable information to support this year's project.

This year's goal is to create a consumer oriented, portable, and air muscle-driven, active ankle-foot orthotic. The system will be required to mitigate the effects of foot drop on varying terrain and include the terrain sensing system previously developed. The project will improve on previous projects by creating a structure that is formed by an aesthetically pleasing flexible exoskeleton to reduce bulk as well as allow a range of users. The AFO device will utilize an onboard micro-controller to interpret sensor data.

  • Active-Ankle Foot Orthotic Family Roadmap

FamilyRoadmap JPG

  • Customer Needs and Objectives:

Objective Number / Customer Objective Description
S1 / follow safety guidelines and standards
S2 / safe for daily operation
S3 / energy stored safely
S4 / no sharp protrusions
S5 / allergy conscious
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
P1 / untethered
P2 / last for a full day without recharging/refueling
P3 / stay secure throughout the day
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
D1 / reliable for day to day usage
D2 / sensors/controls withstand elements
D3 / usable in rain/shower
D4 / washable
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
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 PackageRev 5/18/12

  • Functional Decomposition:


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Project Readiness PackageRev 5/18/12

  • Potential Concepts:
  • Air Muscle "sock": Asymmetric air muscle integrated into fabric type material, creating a device that can be worn like an neoprene ankle support/sleeve. Weight on foot is reduced by air tank or pressure vessel being secured to torso or hip to reduce weight acting on the foot.
  • Soft Exoskeleton with traditional air muscle: Picture show is a system developed by Che-Wei in the Wearables Studio at ITP, NYU. A new system could implement a similar exoskeleton that would aid dorsiflexion, instead of plantar flexion as shown.
  • Air muscle implementation from previous active ankle-foot orthotic teams may also be considered for use with a flexible exoskeleton.
  • Specifications:

Engineering Specification Number / Engineering Specifcation Description / Units of Measure / Preferred Direction / Nominal Value / Stems From Customer Need
s1 / Torque on Foot / N-m / Up / ≥±1.5 / FT1,2,4,ST1,5
s2 / System response time (sensing terrain to actuating device) / ms / down / <150 / ST3
s3 / predicts step up / yes/no / - / yes / ST1,2,4
s4 / predicts step down / yes/no / - / yes / ST1,2,4
s5 / predict flat / yes/no / - / yes / FT1,ST5
s6 / predicts ramp up / yes/no / - / yes / ST1,2,4
s7 / predicts ramp down / yes/no / - / yes / ST1,2,4
s8 / predicts speed of person / m/s / range / ±0.1 / FT1,ST3
s9 / measure angle of foot / degrees / range / ±5 / FT1,2,4,ST4
s10 / allowable range of motion between foot and shin / degrees / range / 94.5 to 137.7 / FT1,3,CF8,9,ST1
s11 / follow safety standards / yes/no / - / - / S1,2,3
s12 / untethered usage time / steps / up / 3000 / P1,2,D1
s13 / charging time from full discharge / hours / down / 8hrs / S3,P1
s14 / fits calf (diameter) / mm / range / 292 to 433 / CF1,3,5
s15 / fits foot (length) / mm / range / 212 to 317 / CF1,3,5
s16 / Time to remove for patient TBD / seconds / down / 180 / C3
s17 / force to secure constraints / N / down / < 80 N / C4
s18 / force to remove constraints / N / down / < 80 N / C3
s19 / Force to remove device from foot when secured / N / up / > 2*AFOWeight / P3,CF3
s20 / hours to fit / hours / down / ≤ 1 hr / 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 / 0.5mm / S4,CF1,2
s24 / weight of entire device / kg / down / ≤3 / FT6
s25 / Harm to user (survey) / scale / down / - / S2,4,5,CF1,CF4
s26 / Noise Level (at ears of user) / dB / down / 60 / 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 / D2
s29 / Overall comfort rating by some sample size / scale / up / - / CF1-11
s30 / Overall aesthetic rating by some sample size / scale / up / - / CF10
s31 / Minimum life until failure / steps / up / *5.5 million / D1
s32 / Allowable toe extension/flexion / degrees / range / 0-50 / 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.

  • Constraints:
  • The system must use air muscles as the means of foot actuation.
  • The exoskeleton skeleton must be made out of a flexible material (ex: cloth, neoprene, leather...)
  • Must use Christopher Sullivan's terrain sensing system .
  • Device must accommodate a general range of population
  • 5th percentile females to 95th percentile males
  • User must be able to wear his/her regular shoes while wearing device
  • No part of the device shall extend above the knee joint
  • The device must follow safety standards as applicable including, but not limited to:
  • Institutional Review Board (IRB)
  • ASME Boiler and Pressure Vessel Code
  • Project Deliverables:
  1. A fully functional active AFO consisting of:
  2. An air muscle actuation device capable of applying torque to and rotating the user’s foot
  3. Implemented circuit interfacing with the sensing system, microcontroller, and actuation device
  4. A flexible exoskeleton that connects all portions of the device to the user including:
  5. Energy storage medium
  6. Actuation device
  7. Terrain sensing system
  8. Microcontroller
  9. Submission of design to ASME Summer Bioengineering Conference
  • Budget Estimate: < $500
  • Intellectual Property (IP) considerations:

If it is a federally funded project, any IP generated as a result of this project will belong to RIT

  • Continuation Project Information:
  • P_____: Developed a tethered active ankle foot orthotic to mitigate the effects of foot drop. This project served as a proof-of-concept of terrain sensing and air muscle technology on an AFO.
  • P_____: Developed an unthered active ankle foot orthotic to mitigate the effects of foot drop. This project used methods developed in the previous proof-of-concept to add portability to the active ankle foot orthotic.

Student Staffing:

  • Skills Checklist: Attached to PRP
  • Anticipated Staffing Levels by Discipline based on the Deliverables listed:

Discipline / How Many? / Anticipated Skills Needed
ME / 2 / ME1: Analysis of exoskeleton interface with components including attachment of micro-controller, sensors, and energy storing device. Support of design and manufacturing of complete device (with all).
ME2: Analysis and design of air muscle actuation device including energy storage component. Integration of terrain sensing and air muscle control system (developed by previous teams).
ISE / 1 / ISE1: Design of exoskeleton (with ID) and human interface, ergonomics of attachment and removal of device, usability, and manufacturability of complete product .
ID / 1 / ID1 (Industrial Design): Design of overall device aesthetics and interaction with user. Support manufacturing and prototype of device.

Other Resources Anticipated:

Category / Description / Resource Available?
Environment / MSD Design Center
Dr. Lamkin-Kennard Lab (Air Muscle Testing)
Equipment / Terrain Sensing Components
2012-13 and 2013-14 air muscle control system (valves and micro controller)
Load cell and acquisition device (Air Muscle Testing)
Materials / 2012-13 Active AFO team documentation
2013-14 Active AFO team documentation
Terrain Sensing Thesis documentation
Prepared by: / Travis Blais / Date: / 5/22/12

Appendix (PRP): Skills Checklist

Project Name (tentative): Active Ankle Foot Orthotic: Untethered Flexible Exoskeleton Air Muscle

Checklist Completed by (name): Travis Blais

Mechanical Engineering:

2 / 3D CAD / Aerodynamics
MATLAB programming / CFD
Machining (basic) / 3 / Biomaterials
1 / Stress Analysis (2D) / Vibrations
1 / Statics/dynamic analysis (2D) / Combustion engines
Thermodynamics / GD&T
1 / Fluid dynamics (CV) / Linear controls
LabView (data acquisition, etc.) / 3 / Composites
Statistics / DFM
Robotics (motion control)
Heat Transfer
Modeling of electromechanical & fluid systems
2 / Fatigue & static failure criteria (DME)
2 / Specifying machine elements

Reviewed by (ME faculty): ______

Industrial and Systems Engineering:

Statistical analysis of data - regression / Shop floor IE - methods, time study
2 / 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 / 3 / Manufacturing engr.
2 / Project management / DFx - Manuf., environment, sustainability
Engineering economy - ROI
Quality tools - SPC
Production control - scheduling

Reviewed by (ISE faculty): ______

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