1. System Design Review P15007: Anti-Rollback Wheelchair
Jessica Jeffrey – Industrial Engineer / Project Manager
Jacob McCarthy – Mechanical Engineer
Warren Roser – Mechanical Engineer
John Sweet – Mechanical Engineer

2. Agenda Background (~2 min) Action Items and Resolutions (~3 min)
System Architecture (~1 min)
Functional Decomposition (~6 min)
Morphological Analysis (~2 min)
Pugh Chart (~10 min)
Concept Selection (~2 min)
Benchmarking (~10 min)
Scope (~3 min)
Risk Assessment (~5 min)
Feasibility (~6 min)
Test Plan (~1 min)
Project Plan (~2 min)
P15007 Anti-Rollback Wheelchair
9/30/2014

3. Background
Users of manual wheelchairs encounter issues when  traversing up an incline or down a decline
P15007 Anti-Rollback Wheelchair
9/30/2014

4. Action Items and Resolutions
Updated Engineering Requirements
Updated Use Scenario
Repair Alpha Prototype
Monroe Wheelchair Visit
Benchmarking Alpha Prototype
P15007 Anti-Rollback Wheelchair
9/30/2014

5. Updated Engineering Requirements
* Functions
Key 9
High 3
Moderate 1
Low
P15007 Anti-Rollback Wheelchair
9/30/2014

6. Updated Use Scenario Aid and Client Interaction
Aid Assists Client into Chair
Client Propels Themselves on Flat Terrain
Aid Available for Steep Inclines/Declines
Aid Instructs Client to Engage/Disengage Hill Holding System
Client Continues Self Propulsion on Flat Terrain
P15007 Anti-Rollback Wheelchair
9/30/2014

7. Ratchet and Pawl System
System Architecture
Client / Aid Input
Ratchet and Pawl System
Disc Braking System
Manual Wheelchair
Engagement
P15007 Anti-Rollback Wheelchair
9/30/2014

8. Functional Decomposition (1 of 3)
Main Function: Control Motion
P15007 Anti-Rollback Wheelchair
9/30/2014

9. Functional Decomposition (2 of 3)
Stop Backwards Motion
Ratchet and Pawl System
P15007 Anti-Rollback Wheelchair
9/30/2014

10. Functional Decomposition (3 of 3)
Impede Forward Motion
Braking System
P15007 Anti-Rollback Wheelchair
9/30/2014

11. Morphological Analysis
P15007 Anti-Rollback Wheelchair
9/30/2014

12. Selection Criteria Material Cost Ease to Transport Labor Cost
Ability to Complete in 2 Semesters
Additional System Weight
Reliability
Additional Width
Safety
COTS Components
Ability to steer down decline
Ability to prevent rollback
Ergonomic Adjustability
Ability to slow on decline
Maintenance
Ability to stop on decline
System Adaptability
Ease of Collapsibility
Ease of Installation
P15007 Anti-Rollback Wheelchair
9/30/2014

13. Pugh Chart (1 of 2) DATUM: Manual Wheelchair
Key +
Improved
Equal -
Diminished
Pugh Chart (1 of 2)
DATUM: Manual Wheelchair
P15007 Anti-Rollback Wheelchair
9/30/2014

14. Pugh Chart (2 of 2) DATUM: Alpha Prototype
Key +
Improved
Equal -
Diminished
Pugh Chart (2 of 2)
DATUM: Alpha Prototype
P15007 Anti-Rollback Wheelchair
9/30/2014

15. Concept Selection Beta Concepts 1 & 2 Multiple Pawls
Mechanical Disc Brakes
User Controls
P15007 Anti-Rollback Wheelchair
9/30/2014

16. Benchmarking: Alpha Prototype
Team Member
Ergonomics
System
Safety
Jessica 1 3
Jacob
Warren
John
Key 9
Excellent 3
Good 1
Poor
P15007 Anti-Rollback Wheelchair
9/30/2014

17. Benchmarking: Monroe Wheelchair Visit
Jonathan Walters, Vice President
Custom VS Standard Options
Rigid Frame VS Collapsible Frame
Spoked Wheel VS Spokeless Wheel
P15007 Anti-Rollback Wheelchair
9/30/2014

18. Benchmarking: Major Brands
P15007 Anti-Rollback Wheelchair
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19. Benchmarking: Major Brands
P15007 Anti-Rollback Wheelchair
9/30/2014

20. Benchmarking: Competitive Solutions
Parameters/
Products
Grade Aid
Magic Wheels
The Pivot
e-motion
D's Locks
ADI Disc Brake
Cost
$180
~$5000
~$4770
$7,
$500+
$750+ (some over $1,150)
Weight
~3 lbs
~10 lbs (additional)
~ 12 lbs (additional)
10 lbs (additional) +
2 lbs
Not Available
Function
Anti-rollback for incline
Hill holding and gear reduction
Dual levers, Parking brake, anti-rollback hill holder
Slows Rollback and assists motion
Locks wheels to prevent chair from moving when transferring in / out of chair.
Manual Braking System
Interfacing
Replaces factory wheel locks
Replaces stock wheels
Replacing quick-release rear wheels
Attaches to wheel and stock axle
Attaches to quick detach wheels on custom chairs
Limitations
Works best with inflatable tires
Price Mostly
Replaces current wheels entirely
Maximum Range of 16 miles, increases width by 1-1.5"
Only used when stationary
Needs to be a quick detach wheel
Maintenance
Sealed gearbox, factory serviced only
Battery Recharge & Replacement
none
Occasional to replace pads or rotor
Universality
Fits most Quickie wheelchairs
Fits most manual wheelchairs with supplied adapter(s), customers are asked to call for verification
Tube diameters 22.2mm, 25.4mm, 28.6mm, 30mm, and 31.8mm (7/8", 1", 1 1/8", 1.2", and 1 1/4").
Only Compatible with manufacturer specified wheelchairs.
Compatible With specified chairs, approx 50 models.
Compatible with a various custom chairs

21. Benchmarking: Grade Aid
P15007 Anti-Rollback Wheelchair
9/30/2014

22. Benchmarking: D’s Locks
P15007 Anti-Rollback Wheelchair
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23. Benchmarking: ADI Disc Brake
P15007 Anti-Rollback Wheelchair
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24. Scope: Retrofittable Possible Target Wheelchairs Standard (Not Custom)
Collapsible Frame (Not Rigid)
Standard Wheels (Not Quick-Release)
P15007 Anti-Rollback Wheelchair
9/30/2014

25. Scope: Users Target Users: Men and Women Age 65+ Any Wheelchair
Any Wheelchair
Manual wheelchair
Electric wheelchair
Number (1000s)
% of population
Total
1,599
0.61
1,503
0.58
155
0.06
Age
Under 18 88
0.12 79
0.11 18
0.02
18-64
614
0.39
560
0.35 90
65+
897
2.87
864
2.76 47
0.15
Gender
Male
658
0.52
606
0.48 84
0.07
Female
941
0.7
0.67 71
0.05
P15007 Anti-Rollback Wheelchair
9/30/2014

26. Risk Assessment (1 of 2)
P15007 Anti-Rollback Wheelchair
9/30/2014

27. Risk Assessment (2 of 2)
P15007 Anti-Rollback Wheelchair
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28. How long does our device have to last?
Feasibility (1 of 3)
How long does our device have to last?
Average wheelchair lifespan, 5-15 years
Insurance company funds replacement every 5 years
Average wheelchair uses travels 1.6km per day
Assume 24” wheel
revs in 5 years
revs in 15 years
P15007 Anti-Rollback Wheelchair
9/30/2014

29. What loads does our device have to support?
Feasibility (2 of 3)
What loads does our device have to support?
Assumed 300 lb load limit
Load applied directly at wheelchair center
P15007 Anti-Rollback Wheelchair
9/30/2014

30. Feasibility (3 of 3)
What is the resolution of the ratchet and pawl and how can we improve it?
24 Inch Wheel
Teethê\Pawls è 1 2 3 40
1.88
0.94
0.63 60
1.26
0.42 80
0.47
0.31
22 Inch Wheel
Teethê\Pawls è 1 2 3 40
1.73
0.86
0.58 60
1.15
0.38 80
0.43
0.29
26 Inch Wheel
Teethê\Pawls è 1 2 3 40
2.04
1.02
0.68 60
1.36
0.45 80
0.51
0.34
P15007 Anti-Rollback Wheelchair
9/30/2014

31. Engineering Requirement
Test Plan
Test
Engineering Requirement
Test ergonomics of controls
Component life tests through theoretical analysis
Designed test life
Test force input to brake down an incline using force gauge. Use wheelchair ramp on campus that is standard 1:12 slope to conduct test.
Grip force exerted by user to brake on decline
Measure wheelchair width with and without system installed, and compare. Do this for the wheelchair in the folded state and in use state.
Increase of wheelchair width when in use; Component interference when wheelchair is folded
Test hold on incline with maximum rated load for standard wheelchair.
Force exerted by user to hold position on incline
Measure total additional weight from installation of the system
Total system weight
Measure time it takes to detach the system and revert to original wheelchair configuration
Time to revert to original configuration
P15007 Anti-Rollback Wheelchair
9/30/2014

32. Project Goals: Phase III
Further Evaluate Feasibility of Concept 1 & 2
Cost Analysis
Maintainability
Functionality
Choose Final Ratchet and Pawl Design
Develop Prototype
P15007 Anti-Rollback Wheelchair
9/30/2014

33. Phase III Benchmark Opportunities
Dr. Day: CP Rochester
Southside Medical Supply
Westside Medical Supply
Access Lifts & Ramps
P15007 Anti-Rollback Wheelchair
9/30/2014

34. Thank You!
P15007 Anti-Rollback Wheelchair
9/30/2014