ME 340 Project 1

DESIGN PROPOSAL

EZ SNAP RAMP: ENABLING THE DISABLED

John McPheron

Seth Forney

Stephen Eshghy

February 12, 2010

Team F

Team F Design Proposal ME 340.6 February 12, 2010 Page 1

Executive Summary

The objective of the design project was to design an effective product to help wheelchair users

independently negotiate four-inch curbs. This proposal details the design method that was

implemented to come up with the final design while exploring a variety or customer needs and

desires. Several varieties of designs were considered and the simplest one was deemed to be the

best one as a result of its ease of use and cost. The final design consists of two perforated steel

ramps that can collapse via snap hinges. A telescoping steel grabber tool is also used in

conjunction with the ramps to position them and pick them up. It is the conviction of the group

that this product is the simplest, least invasive, and safest design for wheelchair users. It is a

shared belief that this is the product wheelchair users will desire most and use for their

independent negotiation of curbs. The EZ Snap Ramp is a great investment for any investor and

will no doubted produce long term profits. Investing in this safe and reliable product is a wise

choice and will lead to very satisfied customers.

Table of Contents Page

Executive Summary 1

1. Introduction 2

1.1 Background 2

1.2 Task Description 2

2. Problem Definition 2

3. Customer Needs Assessment 2,3

3.1 Gathering Customer Input 2

3.2 Weighting of Customer Needs 3

4. Engineering Specifications 4,5

4.1 Establishing Target Specifications 4

4.2 Relating Specifications to Customer Needs 4,5

5. Concept Generation 5,6,7,8

5.1 External Search 5, 6

5.2 Design Concepts 6,7,8

6. Concept Selection 9

7. Final Design 10,11,12,13

7.1 Technical Drawings 10,11

7.2 Technical Assessment 11,12

7.3 NPV and Cost Analysis 12,13

8. Conclusions and Recommendations 13,14

9. References 14,15

Appendices 16,17


1. Introduction

1.1 Background

Wheelchair users are faced with complex problems everyday that wheelchair accessibility poses

to them. There are many locations inaccessible to wheelchair users because of limitations of the

wheelchair and the nature of the location. One such challenge is a four-inch curb, which does not

have a wheelchair accessible ramp or accessibility point. [1] It is near impossible for wheelchair

users to ascend the four-inch curb without the help of another person or accessory. The potential

market for an accessory to help curb ascension is very large as there are currently 3.3 million

wheel chair users in America currently. [2]

1.2 Task Description

The objective of the design is to create an accessory attachment for wheelchairs that can assist a

wheelchair user in ascending a four-inch curb alone. The goal is to design and create an

accessory that easily attaches to the wheelchair which costs less than seventy-five dollars. Safety

and ease of use are the major design considerations that were taken in to account for the project.

The design process employed for the project involved individual brainstorming, followed by

group brainstorming, narrowing of concepts, and final design selection.

2. Problem Definition

A current issue exists for wheelchair users with negotiating curbs independently and quickly.

The problem was presented to the group by paraplegics and was deemed a very important

problem in need of resolution. After experimenting with a wheelchair and analyzing the problem

it has become apparent that 4-inch curbs can prove to be quite a difficult task to overcome. Many

challenges are faced daily by wheelchair users and their independency is threatened as a result.

The current practice is to have assistance from other persons or the attachment of expensive

accessories on to special wheelchairs. Both of these solutions do not meet the needs of the

everyday wheelchair user who desires to be independent while not spending much money on an

attachment. The project was constrained to an overall final market cost of seventy-five dollars.

The group also found it necessary to constrain the product to being safe, versatile, non-invasive

to the wheelchair, and easy to use. Ideation methods that were employed during the project

included benchmarking, individual concept generation, group brainstorming, and concept

screening to choose the final design. The 2.6 millions wheelchair users in America will be the

ones who benefit from the final design project as it will increase their independency and quality

of life.

3. Customer Needs Assessment

3.1 Gathering Customer Input

In order to determine the needs of customers, the team searched relevant websites and analyzed

reviews of existing products. From that, the team created a detailed list of customer needs. These

included ease of use, safety, durability and lifetime, cost-effective, versatile (ability to

accommodate a range of terrains/curbs), ease of assembly, attractive design, and wheelchair

compatibility. (See Appendix A for more on customer input)


3.2 Weighting of Customer Needs Weighting was found to be a very important part of the design process as it helped determine the

final design choice. Weighting the needs insures a product that is focused on customer needs and

the most important aspects of the product. From the list of needs determined through customer

reviews and experimentation, the team grouped the needs in order to create a more manageable

list of needs. These needs were cost, safety, ease of use, features, and specifications. The need of

cost represented the requirement of keeping the accessory under seventy-five dollars. The need

of safety represented the desire to have a product that would not cause accidents and allow users

to safely ascend and descend curbs. The ease of use need requires a product that is easy to

assemble, use, and store. The need of features focused on aesthetics, versatility, and

compatibility with current wheelchairs. The specifications cost required a product that was

lightweight, easy to store, and durable. In order to determine which needs were most pertinent,

the team used the AHP method to create a weighted list of customer needs (see appendix B).

The results can be found in Table 1. [3]

Table 2. Hierarchal Customer Needs Objective List

EZ Snap Ramp 1. Safety (0.51, 0.51)

1.1 User will not tip 1.2 Traction is sufficient C.1 ADA Approved C.2 Does not cause injury

2. Ease of Use (0.30,0.30) 2.1 Easy to ascend 2.2 Easy to Descent F.1 Independent use 2.3 Easy collapse 2.4 Easy to put together

3. Features (0.12, 0.12) 3.1 Snap hinges 3.2 Quick to use F.2 Collapsible

4. Specs (.05, .05) 4.1 Durable 4.2 Lightweight 4.3 Long Lifetime F.3 Product Manageable for Independent

5. Cost (0.02, 0.02) 4.1 Affordable accessory C. 3 Retails under $75.00

Table 1. Weighted customer needs

determined by AHP Method.

Need Weight

Safety 51%

Ease of Use 30%

Features 12%

Specs 5%

Cost 2%


4. Engineering Specifications

4.1 Establishing Target Specifications and Metrics

From the established customer needs, the team compiled a list of engineering specifications to

meet those needs. A strength test would ensure that the product is capable of holding the weight

of most users, a fatigue test would ensure that the product will last, and terrain tests would

determine whether the product is capable of being used in a variety of situations. In addition, the

storage dimensions and weight must be constrained so that anyone is capable of using the

product. Finally, the cost must be constrained to fit within a reasonable budget, and the final

product must be aesthetically pleasing. The list of target specifications can be found in (Table 3).

Table 3. Target Specifications

Metric No. Needs No. Metric Target Value Units

1 1 Strength Test >350 lbs

2 1,3 Fatigue Test 10^6 Cycles

3 2 Assembly Time <= 30 s

4 6,8 Width <= 8 in

5 6,8 Storage Length <= 12 in

6 2,6,7 Total Weight <20 lbs

7 4 Cost <75 $

8 5 Terrain Test Pass Binary

9 9

Attractive

Design >= 4 out of 5 Subjective

4.2 Relationship of Engineering Specifications to Customer Needs

In order to ensure that the customer needs were met, the team created a needs-metrics matrix

(Table 4). For each listed customer need, a relevant engineering specification/metric was created

that could be used to determine whether that need is met. The needs are listed on the left, and the

relevant metrics are listed across the top. An “X” signifies a relationship between a customer

need and an engineering specification.


Table 4. Needs-Metrics Matrix

1.

Strength

Test

2.

Fatigue

Test

3.

Assembly

Time

4.

Width

5.

Storage

Length

6.

Total

Weight

7.

Cost

8.

Terrain

Tests

9.

Attractive

Design

1. Safe to use X X

2. Easy to

assemble/use X X

3. Durable X

4. Cost-

effective X

5. Versatile X

6.

Compatable

with most

wheelchairs X X X

7.

Lightweight X

8. Does not

impede use

of wheelchair X X

9. Attractive

Design X

5. Concept Generation

5.1 External Search

The team began the concept generation process by researching patents and existing products. The

relevant patents can be found in (Appendix C). [4][5][6][7][8] There are very few products on

the market to aid wheelchairs in ascending curbs, but one product that performs a similar

function is the Roll-A-Ramp™. The Roll-A-Ramp™ could be considered as a benchmark leader

for the design despite it not being designed specifically for wheelchairs. [9]


Table 5. Benchmarking of similar products.

Benchmarking Table

Adjustable Height Wheelchair Ramp

Wheelchair Ramp Apparatus

Curb-Climbing Attachment

Wheelchair Tray Accessory

Wheelchair Attachment

Roll-A-Ramp

Design Type

Folding Ramp X

Retractable Ramp X

Rollout Ramp X

Rear Wheel X X

Simple Ramp X

5.2 Design Concepts

The team brainstormed a list of eleven plausible design concepts (Figure 1). Pruning of the

concepts was necessary to narrow down to the choices that would best serve the customer needs.

It was deemed that some of the ideas were clearly over budget or a hindrance to basic

functionality of the wheelchair. After the pruning process, four concepts remained which were

chosen to concept screen and score.

Figure 1. Initial 11 Design Concepts


Concept 1: The first concept (Figure 2) is a simple folding ramp. The ramp is a sheet that would

be able to fold at multiple places in able to be stored on the exterior of the chair. When the user

reaches a curb, he/she takes the folded ramp from its storage area, unfolds it, and places it on the

ground in front of the chair in order to ascend the curb.

Figure 2. Simple Folding Ramp Idea

Concept 2: The second concept (Figure 3) is a retractable ramp. It consists of two separate tracks.

These telescoping tracks can be stored externally on the wheelchair, removed by the user, pulled

out to an appropriate length, and placed on the ground for traversal of the curb.

Figure 3. Retractable Ramp Idea

Concept 3: The third concept (Figure 4) is a roll-up ramp. This ramp is similar to the folding

ramp in that it is a single ramp, but the storage mechanism is different. In this case, the ramp

consists of multiple links which roll up for external storage. When the user approaches a curb,

he/she unrolls the ramps and places them on the ground in order to traverse the curb.


Figure 4. Roll Up Ramp Idea

Concept 4: The fourth concept (Figure 5) is direct modification to the wheelchair. It consists of

props that are attached to the rear of the chair such that the chair can be tilted back, wheeled

toward the curb, and then uses a mechanism to assist the user in climbing the curb.

Figure 5. Rear Prop/Wheel Idea

Table 6. Table of Concept Advantages and Disadvantages

Concept Advantages Disadvantages

1 Simple design

Cost Effective

Works with most wheelchairs

External to wheelchair

Aesthetics

2 Works with most wheelchairs

Cost Effective

Meets Specifications


Aesthetics

3 Innovative

Works with most wheelchairs

Cost Effective

Complex design

Bulky


4 Proven to work with similar products

Meets specifications

Not as safe

Intrusive to wheelchair

Complex design

Requires addition to wheelchair

Expensive


Figure 6. Concept Classification Tree

6. Concept Selection In order to select the final design, the team utilized a concept-scoring matrix (Figure 7). The

above four concepts were scored using the weighted criteria determined in the customer needs

section. The underlined, bold numbers represent the benchmark for that category. In the end, the

concepts were ranked according to their score. Concept 3, the rollout ramp, scored the highest

yet was not chosen to be the final design. The statistical results of the decision matrix matched

up well with the groups qualitative beliefs which were discussed after the matrix. However, after

further debate the decision was made to go with the folding ramps. The group came to the

conclusion that the rollout ramp would cost too much to produce as compared to the folding

ramps.

Table 7. Decision Matrix for Final Concepts

Folding Retractable Rollout Rear Wheel

Criteria Weight Rating Score Rating Score Rating Score Rating Score

Safety 51% 3 1.53 3 1.53 4 2.04 2 1.02

Ease of Use 30% 3 0.9 3 0.9 4 1.2 2 0.6

Features 12% 2 0.24 4 0.48 3 0.36 2 0.24

Specifications 5% 3 0.15 4 0.2 4 0.2 3 0.15

Cost 2% 2 0.04 4 0.08 4 0.08 3 0.06

Total 2.86 3.19 3.88 2.07

Rank 3 2 1 4


7. Final Design

The final design consisted of two folding ramps which are four feet long when unfolded. The

ramp is constructed from perforated A36 Steel which allows for easy grip with the included

telescopic grabber. The ramp is held together by locking hinges which allow for easy assembly

and collapsing of the ramp. The ramp is easily foldable into one foot long in length and

approximately two inches in height. The ramps can then be stored in the wheelchair storage

pockets.

7.1Technical Drawings

Figure 7. Solidworks drawing of final design

Figure 8. Dimensioned Solidworks drawing of one of the pieces of ramp track


Figure 9. Dimensioned Solidworks drawing of grabber tool.

7.2Technical Assessment

The group analyzed one piece of ramp using SolidWorks CosmosWorks simulation software. An

applied 2500 N Force (562 lbs) was used on the ramp section and found that the max stress

received was just under yield strength of 250 MPA. This is an extreme situation as the weight of

wheelchair will not be distributed as such, but was a good benchmark for the product. Assuming

the load is distributed to approximately 4 pieces of ramp at any one time it is safe to assume that

the ramp will not fail under a load of 500lb or below.


Figure 10. Solidworks load analysis of piece of ramp.

7.3 NPV and Cost Analysis

Table 8. NPV Analysis

NPV Analysis

i(discount rate) 0.05

Year Cash In Cash Out NPV

0 $300,000.00 $0.00 -$300,000.00

1 $300,000.00 $375,000.00 $71,428.57

2 $300,000.00 $375,000.00 $68,027.21

3 $300,000.00 $375,000.00 $64,787.82

4 $300,000.00 $375,000.00 $61,702.69

5 $300,000.00 $375,000.00 $58,764.46

6 $300,000.00 $375,000.00 $55,966.15

Total NPV $80,676.91

(See Appendix D For more on NPV Analysis)


Table 9. Cost Estimate

EZ Snap Ramp Cost Analysis

Cost Per Piece

Number of Part Total

Part

Hinges $1/piece 22 $22.00

Steel Material $12/Ramp 2 $24.00

Grabber Material $3/Grabber 1 $3.00

Machining/Labor $6/Product 1 $6.00

TOTAL $55.00

8. Conclusions and Recommendations

The development of the EZ Snap Ramp has been a thorough one that has taken in to account

customer needs and many design ideas. Our group began by analyzing the problem statement of

wheelchair users not being able to ascend or descend 4 inch curbs without assistance. We then

came up with customer needs based on what we believed the customer would want in a

wheelchair accessory. We then were able to experiment with a wheelchair to determine the

capabilities and to better direct our design brainstorm. We then weighted the customer needs and

determined that the top needs in order would be safety, ease of use, features, specs, and cost.

Once the needs were determined, the concept generation began. An external patent search was

conducted to get an idea of the products currently available, as well as to inspire the group to

develop new ideas. In the beginning, no design concept was turned down as all the ideas were

discussed in detail within the group. The group then began to narrow down the possible choices

based on feasibility and cost which left four main ideas of retractable ramp, folding ramp, roll

out ramp, and a prop. Through use of the QFD Chart and a Concept Scoring matrix the choice

was made to go with the folding ramp with the grabber.

The resultant product has been designed around the customer needs, ADA guidelines, safety, and

ease of use. We believe that the simple route was the best route for this case and will be the

easiest for handicap persons to use. The snap hinges will allow the product to be assembled and

collapsed quickly while giving the product great durability. The perforated steel provides

increased traction to prevent the wheels from slipping while scaling the ramp. The guide rails on

the side prevent the wheel chair from going off of the ramps to ensure safe usage. The choice of

the EZ Snap Ramps over our other design ideas was a clear one as it met all the customer needs

while meeting safety and cost requirements. We do not believe that there is any potential for


patent, copyright, or trademark potential given the simplicity of the design and the results of

patent searches that yielded similar results.

Our team is qualified to deliver on the product and promise as we are most interested in helping

others and making the lives of others better. This accompanied with safety were our two main

goals of the project. We have thoroughly researched the problem definition, customer needs, and

design possibilities to develop the best product for the target market.

The product is extremely customer focused and gets back to basics making it the best investment

to satisfy the need. Careful consideration has been given to challenges that handicap persons

have to face on a daily basis and how life can be made easier for them. As a group we believe

that complicated ratchets and levers are costly, unsafe, invasive to the wheel chair, and difficult

to use. The EZ Snap Ramp is an extremely durable and simple to use product that allows

wheelchair users to easily and safely ascend and descend curbs. It also requires no modification

to the wheelchair whereas other products interfere with the collapsing and general operation of

the wheelchair.

There is great economic potential in the EZ Snap Ramp for investors and customers as one can

see from the NPV analysis. Investors will be investing in a sound, proven, durable product that

will satisfy their customer needs. With 3.3 million Americans in wheelchairs, there is a large

need for the product. With production cost at only $55 per piece with opportunity for lower cost

in bulk, the potential for profit is large. The product will also satisfy the customer in an

economic sense as the cost of $75 is well worth the ability to ascend and descend curbs

independently. The production and sale of the EZ Snap Ramp is a great choice for all those

involved. As Group F, we are most interested in the happiness of our customers and success of

our investors and we guarantee this product will deliver both.

9. References

[1] ADA Accessibility Guidelines for Buildings and Facilities. Americans with Disabilities Act,

2002. Retrieved February 11, 2010 from the WWW: http://www.access-

board.gov/adaag/html/adaag.htm#4.7

[2] Facts for Features: Americans with Disabilities Act: July 26. U.S. Census Bureau, 2009.

Retrieved February 11, 2010 from the WWW: http://www.census.gov/Press-

Release/www/releases/archives/facts_for_features_special_editions/013739.html

[3] Karl Ulrich and Steven Eppinger, Product Design and Development, Fourth Edition,

McGraw-Hill Irwin, 2007.

[4] Crump, Robert. 1990. Adjustable Height Wheelchair Ramp with Supporting Legs.

U.S. Patent 4,912,796, filed January 13, 1989 and issued April 3, 1990.


[5] Labreche, Brent J. 1994. Wheelchair Ramp Apparatus. U.S. Patent 5,325,558, filed

October 4, 1993 and issued July 5, 1994.

[6] Locke, Burton H. 1971. Curb-Climbing Attachment for Wheel Chairs. U.S. Patent 3,573,887,

filed May 19, 1969 and issued April 6, 1971.

[7] Rundle, Christopher. 1996. Wheelchair Tray Accessory. U.S. Patent 5,588,663, filed May 15,

1995 and issued December 31, 1996.

[8] Coffey, H. Franklin. 1971. Wheelchair Attachment. U.S. Patent 3,580,591, filed

December 24, 1968 and issued May 25, 1971.

[9] Roll-A-Ramp. Retrieved February 11, 2010 from the WWW: http://www.rollaramp.com/.

[10] 1800 Wheelchair. Retrieved February 11, 2010 from the WWW:

http://www.1800wheelchair.com/.


List of Appendices

Appendix A –Customer Input

Appendix B – AHP Matrix used to weight customer needs

Appendix C – Relevant Patents.

Appendix D – NPV Analysis

Appendix E – Team Credentials

Appendices

Appendix A (reviews from 1800wheelchair.com) [10]

“Easy to use, safe and stores easily.”

“Hard plastic handle interfered with using ramp. Had to saw handle off to use ramp. "No handle"

makes it more difficult to pick-up and carry ramp.”

“…very simple to install…”

“…given me the freedom to get out of my home without any help.”

“A ramp that isn’t too steep.”

“Ability to support significant weight.”

“A ramp that has a non-slip surface.”

“Snap design that accommodates various curbs.”

“…quiet ramps…”

“Ramps that are easy to transport.”


Appendix B (AHP Matrix of Customer Needs)

Safety Ease of

Use

Features Specifications Cost Total Weight

Safety X 5 7 7 8 27 0.51

Ease of Use 1/5 X 4 5 7 16.2 0.6

Features 1/7 1/4 X 2 4 6.39 0.24

Specifications 1/7 1/5 1/2 X 2 2.84 0.15

Cost 1/8 1/7 1/4 1/2 X 1.02 0.06

Appendix C (Relevant Patents)

1. Adjustable Height Wheelchair Ramp with Supporting Legs.U.S. Patent 4,912,796

2. Wheelchair Ramp Apparatus. U.S. Patent 5,325,558

3. Curb-Climbing Attachment for Wheel Chairs. U.S. Patent 3,573,887

4. Wheelchair Tray Accessory. U.S. Patent 5,588,663

5. Wheelchair Attachment. U.S. Patent 3,580,591

Appendix D (NPV Analysis)

Cash In Explained Cash Out Explained

Ramps Made 30000 Ramps Sold 30000

Cost of Ramp 60 Sell Price 75

Cash In Total 1800000 Cash Out Total 2250000

Cash In Per Year 300000

Cash Out Per Year 375000

Appendix E (Team Credentials)

John McPheron – Mechanical Engineering Student (Senior)

Seth Forney – Mechanical Engineering Student (Junior)

Stephen Eshghy – Mechanical Engineering Student (Senior)

Documents

ME 340 Project 1