P14007: Wheelchair Assist

Introduction

• Che-An Lee – Industrial and Systems Engineer• Dan Schuster – Mechanical Engineer• Phil Medalie – Mechanical Engineer• Tom Elliot – Electrical Engineer

Agenda

• Problem Statement• Current Product• Expected Project benefits• Deliverables• Customer Requirements• Benchmarking Specs• Engineering Requirements

Problem Statement• Current State

– Current anti-roll back devices exist that can be added onto wheel chairs, as well as motorized wheel chairs to provide movement assistance

– Majority of manual chairs do not come standard with these devices – Many of these assistance devices are expensive and inhibit some of the benefits of manual chairs

• Desired State– The device should maintain all of the benefits of a manual wheel chair(light weight, small turning radius,

compact, etc.)– The device should also be able to aid the user when traversing inclines and declines, as well as prevent roll

back when moving up an incline• Project Goals

– Design a system that encompasses the desired properties while maintaining the key benefits of a manual chair– Key Desired Properties

• Ability to provide movement assist up inclines• Ability to decelerate the user when moving down declines• Ability to prevent the wheel chair from rolling back down a hill and slipping out from under user

• Constraints– The wheel chair should still meet ADA standards regarding size constraints(doorways, buildings, etc.)– System Cost

Current Product• Anti-Rollback Devices• MagicWheels

• Manual Chairs• Motorized Chairs

Image References: http://www.rehabmart.comhttp://www.magicwheels.com/

Expected Project benefits

● Solutions for manual wheelchair users● Engineering design experience● Basis for future senior design project

Deliverables

• Functional prototype that has the potential to be manufactured

• Test data verifying engineering requirements• Bill of materials• Detailed design with documentation• User’s guide for operation

Customer Requirementsrqmt. # Importance Customer Requirement

C1 9 "Hill Holder"C2 9 De-acceleration downhillC3 1 Movement assist up hillC4 3 Detachable designC5 3 Low weightC6 3 CollapsibleC7 9 Low costC8 9 Medically approved for useC9 3 Small turning radiusC10 3 Size, overallC11 3 Large user weight rangeC12 3 Disengagable devices

Benchmarking SpecsBenchmarked Wheel

Chair Values

rqmt. # Importance Source Engr. Requirement (metric) Unit of Measure Marginal Value Target Value Manual Powered

S1 9 C1 Maximum weight at incline of 10 degrees where the wheel chair does not roll backwards

lbf 260 300 298.3 308.33

S2 9 C12 User/Assistor disengageable Hill Holder seconds 5 2 - -

S3 9 C12 User/Assistor engageable Hill Holder seconds 1 0.5 - -

S4 9 C1 Maximum incline angle, before tipping over backwards with user weight of 300lbf Same as original Better than

original - - -

S5 9 C2 Maximum downhill speed at decline of 10 degrees at 300lbf user weight

mph 4 3 - 4.58

S6 9 C12 User/Assistor disengagable Gradual Grade seconds 5 2 - -

S7 9 C12 User/Assistor engagable Gradual Grade Seconds 1 0.5 - -

S8 9 C3 Desired Movement Assist Input Force Ratio Ratio 1.5 2 - -

S9 9 C12 User/Assistor Disengagable movement assist seconds 5 2 - -

S10 9 C12 User/Assistor engagable movement assist Seconds 1 .5 - -

Benchmarking Specs Cont’Benchmarked Wheel

Chair Values

rqmt. # Importance Source Engr. Requirement (metric) Unit of Measure Marginal Value Target Value Manual Powered

S11 3 C5 Wheel Chair Assist System Weightlbf

20 15 - -

S12 3 C5 Total System Weight(Chair Plus Assist) lbf 50 40 33.7 197.3

S13 3 C7 Cost of Wheel Chair Assist System $ 1000 500 $676.60 $3,824.50

S14 3 C6 Wheel chair width when folded in 26 18 - -

S15 9 C9 Wheel chair turning radius ft 2 1 0 2.12

S16 3 C4 Time to remove wheel chair assist system minutes 15 10 - -

S17 3 C10 Length of Wheel Chair + Movement System in 48 30 29.58 36.21

S18 3 C10 Width of Wheel Chair + Movement System in 48 30 23.58 23.5

S19 3 C8 Critical mechanical components have X number of use cycles

cycles 4000 5000 - -

Engineering Requirementsrqmt. # Importan

ce Source Function Engr. Requirement (metric) Unit of Measure

Marginal Value Target Value Ideal Value Comments/Status

S1 9 C1 System Operation

Maximum weight at incline of 10 degrees where the wheel chair

does not roll backwardslbf 260 300 400

Assuming the wheelchair doesn't tip

over during test

S2 9 C12 System Operation

User/Assistor disengageable Hill Holder seconds 5 2 1

Can be disengageable by user/assister; should

work like an on/off switch

S3 9 C12 System Operation

User/Assistor engageable Hill Holder seconds 1 0.5 0.1  

S4 9 C1 System Operation

Maximum incline angle, before tipping over backwards with user

weight of 300lbfDegrees Same as

originalBetter than

original    

S5 9 C2 System Operation

Maximum downhill speed at decline of 10 degrees at 300lbf

user weightmph 4 3 User Varied  

S6 9 C12 System Operation

User/Assistor disengagable Gradual Grade seconds 5 2 1

Can be disengageable by user/assister; should

work like an on/off switch

S7 9 C12 System Operation

User/Assistor engagable Gradual Grade seconds 1 0.5 0.1  

S8 9 C3 System Operation

Desired Movement Assist Input Force Ratio Ratio 1.5 2 3 Without system/with

system

S9 9 C12 System Operation

User/Assistor Disengagable movement assist seconds 5 2 1

Can be disengageable by user/assister; should

work like an on/off switch

S10 9 C12 System Operation

User/Assistor engagable movement assist seconds 1 0.5 0.1  

Engineering Requirements Cont’rqmt. # Importa

nce Source Function Engr. Requirement (metric) Unit of Measure

Marginal Value Target Value Ideal Value Comments/Status

S11 3 C5 System Portability

Wheel Chair Assist System Weight lbf 20 15 10 User and chair not

included in weight

S12 3 C5 System Portability

Total System Weight(Chair Plus Assist) lbf 50 40 35  

S13 3 C7 System Operation

Cost of Wheel Chair Assist System $ 1000 500 200 Production level costs

S14 3 C6 System Portability Wheel chair width when folded in 26 18 Unchanged

original widthBased on the

customer's wheelchair

S15 9 C9 System Operation Wheel chair turning radius ft 2 1 0  

S16 3 C4 System Portability

Time to remove wheel chair assist system minutes 15 10 5  

S17 3 C10 System Operation

Length of Wheel Chair + Movement System in 48 36 Unchanged from

originalBased on the

customer's wheelchair

S18 3 C10 System Operation

Width of Wheel Chair + Movement System in 48 36 Unchanged from

originalBased on the

customer's wheelchair

S19 3 C8 System Operation

Critical mechanical components have X number of use cycles cycles 4000 5000 6000

This will be tested computationally and/or

with a finite element analysis

Questions/Comments?