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 C1Maximum weight at incline of 10 degrees where

the wheel chair does not roll backwardslbf 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 C1Maximum incline angle, before tipping over

backwards with user weight of 300lbf Same as originalBetter than

original - - -

S5 9 C2Maximum downhill speed at decline of 10

degrees at 300lbf user weightmph 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 C8Critical mechanical components have X

number of use cyclescycles 4000 5000 - -

Engineering Requirementsrqmt. #

Importance

Source Function Engr. Requirement (metric)Unit of

MeasureMarginal

ValueTarget Value Ideal Value Comments/Status

S1 9 C1System

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 C12System

OperationUser/Assistor disengageable Hill

Holderseconds 5 2 1

Can be disengageable by user/assister; should

work like an on/off switch

S3 9 C12System

OperationUser/Assistor engageable Hill

Holderseconds 1 0.5 0.1  

S4 9 C1System

Operation

Maximum incline angle, before tipping over backwards with user

weight of 300lbfDegrees

Same as original

Better than original

   

S5 9 C2System

Operation

Maximum downhill speed at decline of 10 degrees at 300lbf

user weightmph 4 3 User Varied  

S6 9 C12System

OperationUser/Assistor disengagable

Gradual Gradeseconds 5 2 1

Can be disengageable by user/assister; should

work like an on/off switch

S7 9 C12System

OperationUser/Assistor engagable

Gradual Gradeseconds 1 0.5 0.1  

S8 9 C3System

OperationDesired Movement Assist Input

Force RatioRatio 1.5 2 3

Without system/with system

S9 9 C12System

OperationUser/Assistor Disengagable

movement assistseconds 5 2 1

Can be disengageable by user/assister; should

work like an on/off switch

S10 9 C12System

OperationUser/Assistor engagable

movement assistseconds 1 0.5 0.1  

Engineering Requirements Cont’rqmt. #

Importance

Source Function Engr. Requirement (metric)Unit of

MeasureMarginal

ValueTarget Value Ideal Value Comments/Status

S11 3 C5System

PortabilityWheel Chair Assist System

Weightlbf 20 15 10

User and chair not included in weight

S12 3 C5System

PortabilityTotal System Weight(Chair Plus

Assist)lbf 50 40 35  

S13 3 C7System

OperationCost of Wheel Chair Assist

System$ 1000 500 200 Production level costs

S14 3 C6System

PortabilityWheel chair width when folded in 26 18

Unchanged original width

Based on the customer's wheelchair

S15 9 C9System

OperationWheel chair turning radius ft 2 1 0  

S16 3 C4System

PortabilityTime to remove wheel chair

assist systemminutes 15 10 5  

S17 3 C10System

OperationLength of Wheel Chair +

Movement Systemin 48 36

Unchanged from original

Based on the customer's wheelchair

S18 3 C10System

OperationWidth of Wheel Chair +

Movement Systemin 48 36

Unchanged from original

Based on the customer's wheelchair

S19 3 C8System

OperationCritical mechanical components

have X number of use cyclescycles 4000 5000 6000

This will be tested computationally and/or

with a finite element analysis

Questions/Comments?