Creating Web Pages in your Account – Computer Action Team



Executive Summary

There are two different walkers in the market today. A traditional walker and what is called a Rollator. Traditional walkers are very basic. They are comprised of grips and four height-adjustable legs that surround the user for stability. Rollators add wheels, large or small, for maneuverability and some have the option of adding a seat or basket. Both are designed to fold up for easy storage.

Walkers usually come in one, drab gray, color that look much like a cold medical device, and the design needs an update. Walkers were designed for remedial tasks that do not require a lot of time to execute. Rollators are very bulky, not easily maneuvered, require an uncomfortable walking position, and only come in a limited variety of colors. Rollators are typically used for larger tasks that require more time than a walker can provide for comfort and ease-of-use issues. A problem arises when not one walker/rollator can be used for every purpose.

Keen Mobility, the team’s sponsoring company, requested the development of a ‘best-of-both-worlds’ walker. A walker that not only provides the simple task of giving users mobility assistance, as in the traditional walker, but a walker that is also attractive, maneuverable, and user-friendly, as in the Rollator.

The design team has developed a walker that meets these needs. It was designed to be comfortable for up to 8 hours of use, by including ergonomic handles, and multiple adjustment options to personalize the ‘fit’ of the walker to the user. The walker includes Keen Mobility’s trademark shock absorbers to reduce vibration. There are 3 different feet options, allowing the user to choose which one best fits their needs. The walker weighs less than 6 pounds, which makes it easier to maneuver and easier to store in a trunk of a car. The walker also includes many curves to give it a more appealing look.

Table of Contents

Executive Summary 1

Table of Contents 2

Introduction & Background Information 3

Mission Statement 4

Main Design Requirements 4

Top Level Alternative Conceptual Solutions 5

Chosen Design 7

Justifications for Final Design 7

Final Design 8

Evaluations 12

Conclusion 13

Appendix A – Walker Drawings 14

Appendix B – Walker Use Discovery 18

Appendix C – Important Tips from Actual Walker Users 19

Appendix D – Curved Beam Analysis 20

Appendix E – Bill of Materials 24

Appendix F – House of Quality 25

Appendix G – Detailed External Search 26

Appendix H – Detailed Internal Search 27

Appendix I– Detailed Concept Evaluation 28

Appendix I – Discovery from the Prototype Process 33

Appendix J – Albina RFQ Sheet 34

Appendix K – Rapid Prototype Material 35

Introduction & Background Information

Walkers and rollators are an essential part of life for many people who have mobility challenges. The design team has worked with Keen Mobility to make activity a comfortable and enabling experience. Keen Mobility is an innovative company that manufactures and distributes medical devices that empower individuals by allowing them to be independent and mobile. Upon meeting with Keen, it became clear that there was an explicit need for a walker renovation. The traditional walker (Figure 1), not to be confused with a current rollator (Figure 2) which commonly has wheels and a brake system, was not meeting the needs of the users. The design was not ergonomically correct as it was hard for the user to maneuver, especially when the user has mobility impairments. Both products were also complicated to fold and store in vehicles or under a seat in a restaurant. The current rollator also was not ergonomic since it forced the user to bend over and reach forward during use, putting unnecessary strain on their back and neck.

Just a few of the improved features of the renovated walker include height and width different adjustments, improved ergonomics and better aesthetics. There is a defined niche that the renovated walker fulfills among the various rollators and the traditional walker. The renovated walker will combine the aesthetic qualities of the current rollator and the ease of use of the traditional walker.

Mission Statement

The design team’s mission was to design and produce a more ergonomic walker that was adaptable to various customer needs. The main walker design constraints included: being less than 12 pounds, a width adjustment of ±2.0 inches, a 2.0 inch offset of each rear leg, and must incorporate Keen Mobility’s shock absorbers.

Main Design Requirements

1. The walker must be easy to use. Customers using walkers already have a difficult time moving around. The walker needs to be adjustable in both width and height to more easily fit individuals, easy to fold, able to fit in a 6.0 inch gap, and have a small turning radius for maneuvering ease.

2. The walker must be safe to use. Walkers are designed for two different weight classes. A 300+ pound class, and a less than 275 pound class. The walker needs to be designed for under 300 pounds.

3. The walker must perform well. Walkers are only designed to provide mobility assistance and can be very uncomfortable while doing so. The walker needs to have ergonomic handles that distributes the user’s weight evenly across the palm while still easy to hold onto. The two front legs need to have dampers in them to absorb vibrations transmitted from the walking environment. These two features will increase the time users can use the walker by limiting fatigue.

4. The walker must have an acceptable size and shape. People come in all shapes and sizes. To address this, the walker was made of lightweight aluminum, adjustable both in width and height, and has a 2.0 inch rear-leg offset for individuals with a wider gait. A seat was not included in the walker design in order to allow ample walking space inside the walker. This creates a more ergonomic upright stance for the user.

5. The walker must be inexpensive. Medicare pays a maximum of $117 for individuals who need walkers. The walker needs to cost no more than $110.

6. The walker must be attractive. Marketing required a ‘sexy’ walker. To accommodate this, many curves were included in the design. The walker will also be available in at least three colors, and for an extra charge any color can be made.

Top Level Alternative Conceptual Solutions

The team considered a number of rough designs that would satisfy the adjustability and fold-ability requirements. These proposed designs were rejected for a variety of reasons. Three ideas that showed early promise are presented here.

Tripod

This design would have featured a three footed walker with a lockable pivot located at the front wheel (Figure 3). Simply changing the angle of the arms would have allowed for changes in the width of the walker in a manner similar to the opening or closing of a pair of garden shears. The same mechanism could be used to fold the walker for storage. One problem was that if the arms change angle then so do the handles. That would have presented ergonomic difficulties for a person trying to grip those handles at an awkward angle. The proposed solution would have been some compensating angle adjustment located near the handles but that introduced complications and simplicity was one of the real appeals of this design. A further, more serious problem was that tripod arrangements are less stable platforms for people relying on a walker for stability.

Stroller

The idea behind this design was to have both the cross-link and side arms supported by means of crossing bars (Figure 4). The folding mechanism would be analogous to that of an umbrella stroller or a portable lawn chair. Adjustability would be achieved by providing intermediate stops so that the folding process could be done to any preset distance. The main down side to this design came from input provided from the nursing facility that the team visited when conducting the external search. The care providers interviewed requested that nooks and crannies be kept to a minimum to make cleaning as easy as possible. They further noted that some of their clients were prone to getting food particles and other biological materials stuck into crevices, which posed a possible health risk. The stroller design would have introduced as many as seven open hinges and six sliders (or possibly slots), all of which provided potential for contamination.

Shopping Cart

The motivation behind this design was to get the supporting frame out of the way of a person’s feet so that they could walk freely (Figure 5). An added benefit would be that the user would have a mostly unobstructed view and would be more able to minimize the mental awareness that they are using a mobility assistance device. There were two main reasons why this design was not pursued. First, it does little to facilitate the desired goals of adjustability and fold-ability in and of itself. Second, and more inconvenient, the location of the handles and feet virtually insures that the user would be off balance. The center of gravity would necessarily be too far forward and people that required a more stable platform would be unable to comfortable use the device.

Chosen Design

Several designs were attempted prior to finalizing the adjustable, ‘sexy’ walker. The current final design, which the first prototype was based on, utilizes width and height adjustments, wider back legs for wide walking gaits, ergonomic handles, ball feet, and an aesthetic appeal (Figure 6). The chosen design also incorporates the Keen shock absorber.

This design was chosen due to the ergonomic stance of the person using the walker. This walker utilizes the simplicity of the traditional walker by placing the user inside the walker, not behind it, like the rollators. This creates an upright stance while holding the handles of the walker.

This walker also had the approval of Keen Mobility’s marketing department. It was important that the walker have a new innovative appearance. This walker combines the aesthetically pleasing aspects of the rollator, but also provides a healthier posture for the user.

Justifications for Final Design

6063 T7 aluminum was used because it is lightweight, strong, and readily available. A lighter weight walker translated to a more comfortable walker, which means the walker could be used for longer periods of time. 6063 T7 aluminum provided high enough strength so that it is still strong enough to handle stresses from basic walker operation post-welding, since welding tends to reduce material strengths. 6063 T7 aluminum is also relatively inexpensive.

Ergonomically designed handles are used to provide a more comfortable and effortless interaction with the walker. The handles were designed to be ambidextrous (right or left hand) which reduces manufacturing costs. The walker needs ergonomic handles to enhance the comfort level which is related to comfort and longer durations of use.

A Keen Mobility shock absorber is in each leg of the walker. These shock absorbers not only reduce harsh impact forces encountered when using the walker, they also provide a more stable walker platform by conforming to the terrain by keeping all four legs firmly planted on the ground. Also, this walker was designed specifically for the sponsoring company, Keen Mobility, and they insisted on incorporating their shock absorbers into the design.

The look and shape of the walker is curvy and sleek. A ‘sexy’ walker design was required by Keen Mobility, because it needs to stand out among all other walkers. The handle rods, legs and gussets all have a designed radius. These rounded sections eliminate the impression of a cold, institutional looking walker.

The foot print of the walker is new. Width adjustability is designed into the walker to accommodate various users. The back legs are 2.0 inches wider on each side than the front legs to accommodate users with a wider gait.

Final Design

By taking the best qualities of the existing walkers and rollators, and meeting the criteria of safety, lightweight, and a low retail cost, the renovated Keen walker is sure to help those with mobility challenges. The chosen design, a curvy walker with a width extension of +/- 2.0 inches, a height extension of +/- 3.0 inches (Figure 7) and a base width projection of +2.0 inches on either leg (Figure 8) provides the user with an aesthetically pleasing, yet accommodating mobility device. These adjustments allow the user to personalize the fit of the walker to allow a more comfortable experience.

The revised chosen design also incorporates ergonomically correct handles, with a palm flange for extra support (Figure 9). The handles are ambidextrous universal, for simple manufacturing. The handle material was chosen to be cast urethane elastomer- 60A. A test piece by Quickparts was examined, where the cast urethane elastomer- 60A had a tensile strength of 685 psi, a shore hardness of 60 A, shrinkage of 0.003 in/in, and tear strength of 57 psi. Unfortunately, budget constraints prevented the production and use of this material, and stereo lithography was selected. The first prototype of the handles is made of DMS Somos 9120 Epoxy Photopolymer (see Appendix K). This material has a tensile strength of 4400 psi, a shore hardness of 80, and a flexural strength of 6000 psi.

A key notch is machined into the aluminum rod where the handle is attached (Figure 10). This key notch is necessary to eliminate the possible twisting of the handles when they are in use. The fit between the aluminum rod and the ergonomic handle is a friction fit, but for safety and the unlikely possibility the torque applied to the handles exceeds the friction force of the fit, the key notch was utilized.

The legs of the walker utilize the Keen Mobility shock absorber, to alleviate stress in the user (Figure 11). The signature Keen shock absorber utilizes grooves along the shaft to improve strength and stress resistance. The shock absorber is another feature that improves upon the ergonomics of the traditional walker.

A solution was required for the typical ‘tennis-ball-feet’ used for easy gliding on smooth surfaces, resulting in the design of 3 feet. The user will have the option of a spherical ball foot, similar to the tennis ball (Figure 12), a 5.0 inch castor if desired (Figure 13), and a stub end, similar to a cane (Figure 14). By providing choices, the user is allowed more freedom to choose his/her best mobility method. The ball foot was produced for the first walker prototype, manufactured by stereo lithography. The chosen design material was cast urethane elastomer- 60A as well, however costs prevented this. The ball foot also incorporates the Keen signature foam disc, shown in blue in Figure 12Error! Reference source not found.. The disc provides shock absorption and flexibility within the ball foot.

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The final product will be made of 6063 T7 aluminum, although the initial prototype is 6063 Brite Aluminum. Production of the 6063 Brite aluminum walker came with many challenges. Due to the various radii in the curved aluminum, committing a pipe bender proved to be very difficult. Two companies were contacted regularly, Albina Pipe Bending and Tubular Solutions Inc (TSI). Initially, Albina committed to the project, dependent upon using 6063 T7 aluminum due to availability and the difficulty of the bends. Later, wall thicknesses became a problem, so another design change was incurred. The wall thickness was changed from 0.035 inches to 0.049 inches due to the possibility of failure and damage to the material. Finally, after two weeks of design changes, Albina rejected the project due to not having the proper dies for the tube bending.

Tubular Solutions, Inc. (TSI) was contacted next. TSI had previous connections with senior capstone projects from Oregon State University and University of Portland. Although TSI had negative feelings toward student projects due to a constant change of design, they accepted. It was established that 6063 T7 aluminum with a minimum wall thickness of 0.049 inches would be used, based on the experience with Albina. TSI confirmed the project. The next week, TSI rejected the project due to difficulty in aluminum bending. The design team chose an alternate route, using plain carbon steel with the same dimensions, for visual and test purposes. However, the following week TSI again denied the design due to not having the proper dies for the various radii. The design team then decided to use the die available, meaning instead of 5.0”, 6.0”, and 7.0” radius bends, all the bends would be 5.5” radius bends.

In the last week of the capstone series, Steve Heuer accepted the project, using 6061 aluminum Brite. The prototype is for visual and test purposes, due to minor adjustments to the design. Alterations include not being able to fold due to welds, having too tight clearances in the front crossbars thus preventing width extension, and having solid rather than hollow base feet thus preventing use of the shock absorber. However due to previous challenges, and the manufacturing time constraint of one week, the first prototype is acceptable. One advantage of the initial prototype is exceeding the weight specification, weighing approximately 3 pounds.

With Keen Mobility’s goal of manufacturing overseas, the walker should have better success in production, because of mass projections. Also, the correct dimensions will be attained.

Evaluations

A prototype was built, but has not yet been tested. What was learned from building the prototype was that it was not an easy design to build, so the cost of the walker could not yet be determined.

The handles were modeled so that they work universally, for the left and right hands. This makes the handles less expensive to manufacture since only one mold has to be made.

The feet were designed so that they solve the problem of the ‘tennis-ball-feet’. The round design glides more easily on the floor and does not pick up small pieces of debris that would leave streaks on the floor like conventional walker feet. The feet were also modeled after Keen Mobility’s Adventure Tip™ (Figure 15), which has more flexibility due to the foam donut around the middle of the foot.

The shocks were constructed using existing Keen Mobility parts. The shocks allow more ergonomic use of the walker, since they alleviate stress on the user.

The frame was made of 6063 Brite aluminum. This could not be tested due to time constraints. Instead, the strength was verified using finite element analysis using the program I-DEAS. Using this method, the safety factor was found to be 2.16 with a load of 300 pounds. The weak point in the walker was determined to be where the handle bar meets the curved sections. Initially, the handle bar was also a hollow tube, but due to these findings, it was changed to a solid tube, which made the weak point of the walker much stronger. This was also verified by using curved-beam-analysis (see Appendix D).

Conclusion

To assess the final design and success of the walker renovation, many things were considered. The most important of which being ease of use, safety, ergonomics, and appearance.

The main decisions within the walker renovation consisted of how to include the width adjustment, improve the ‘tennis-ball-feet’, maximize the comfort for the user, increase maneuverability, and improve the overall appearance.

The prototype was successful in proving that the overall appearance was better looking than conventional walkers. It also proved that it is more ergonomic than rollators or walkers, due to the handles, the placement of the handles (so that the user walks inside the walker, not behind it), and the multiple adjustments possibilities to personalize the ‘fit’ of the walker to the user. It also proved that the walker met the size and shape criteria that it had to be lightweight, since the prototype was approximately 3 pounds.

The safety of the walker was determined by using finite element analysis and curved beam analysis. Using these methods, the safety factor was found to be 2.16, resulting in a load capability of 648 pounds. The compression testing of the walker could not be done due to time constraints, but Keen Mobility will have it done before it goes to market.

Appendix A – Walker Drawings

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Appendix B – Walker Use Discovery

In February 2006, the five team members met with Keen Mobility, and borrowed five different walkers or rollators. In order to really feel the effects, the five team members walked back to campus using the walker or rollator, a total of one mile. It was found that each walker had its own idiosyncrasies, and no one product was found to exceed the others. Each had disadvantages, including: causing the back to be hunched over, leading in one direction at all times, being uncomfortable, heavy and cumbersome. Each product was difficult to place in a vehicle trunk and left the user with a sore neck.

The experience of using a walker/rollator was very useful. Having hands-on experience provided more meaning to the redesign, affording opportunities to really invest in the walker. The criteria of simplicity, lightweight and ease of use truly became profound after using the walkers firsthand.

Appendix C – Important Tips from Actual Walker Users

• “Easy height adjustments. It always takes too long to adjust the walker while I am using it, so I usually just suffer through being uncomfortable.”

• “It would be fun to make it different colors instead of the boring plain walkers that we are forced to use.”

• “The handles need something done to them… they hurt my hands after just a half an hour of using the walker.”

• “I need bigger wheels. When I went to the county fair to visit my grandson’s pigs, the dang walker caught on every piece of gravel, it seemed like. I don’t want to just be stuck at home or walking around inside a mall.”

IMPORTANT TIPS FROM CAREGIVERS:

• “Easily adjustable dimensions to make it easier to maneuver in the nursing homes.”

• “Different feet for the walker. The tennis balls that are put on the feet to create an easier walk on slick floors often pick up dirt and dust.”

• “Make it lightweight so it is easier for the elderly to use.”

Appendix D – Curved Beam Analysis

SUMMARY: Keen Walker

(1) Objective of the analysis:

For the renovated Keen Mobility walker, a load is placed on the two handles by the user, creating a tensile stress on the top of a 6063 T7 Aluminum tube, and a compressive stress on the bottom of the tube. The objective is to determine a safety factor against yielding, based on a load of 300 pounds per handle. The walker will be rated up to 300 pounds, so by accounting for this load on a single handle, a safety factor of two is predetermined.

(2) Part of product subject to analysis:

(3) PDS criteria relevant to analysis:

The PDS criteria fulfilled is within safety, demonstrating the importance of the calculation. It is also pertinent to product specifications, liabilities and ratings.

(4) Format of expected results:

After computing the compressive and tensile stresses induced by the 300 pound load, a safety factor for yielding will be determined. A safety factor greater than one will be considered acceptable.

(5) Results:

Single handle (300lb): Tension n = 1.8

Compression n = 2.1

(6) Evaluation of the results:

By assuming a load of 300 pounds on a single handle, a greater safety factor for the walker is provided. Both stresses have safety factors greater than one for a load of 300 pounds, and therefore are acceptable. The calculation is valid, based on the assumptions that a moment is created at the tip of the handle, due to the 300 pound load. It is also assumed that the handle is subjected to eccentric loading, and by considering the large radius in the curve of the handle, all major components are accounted for.

The analysis may deviate from the results by using a different aluminum alloy in place of the 6063 T7 aluminum. Another source of deviation would be if the user exceeds the weight limit, inducing failure.

The Keen Mobility renovated walker meets the predetermined criteria of being safely rated up to 300 pounds. A safety factor of n = 1.8 for tension, and n = 2.1 for compression meets the requirements, based on 300 pounds on a single handle.

FORMULATION: Keen Walker

The Keen walker is to have a rating of 300 pounds, based on a load at the tip of the handle of a 6061 Al tube. A safety factor against yielding for a single handle is to be determined.

GIVEN:

F = 300 lb

do = 1”

di = 0.902”

R of handle curve = 6” ( ri of curve = 5.5” ro of curve = 6.5”

Sy (6061 Al) = 78600 psi

ASSUMPTIONS:

• The load is at the tip, shown in free body diagram

• The radius of the neutral axis of the handle is accounted for by: [pic]

FIND: (1) n (tension) for F = 300

(2) n (compression) for F = 300

ANALYSIS:

F = 300 lb

do = 1”

di = 0.902”

R of handle curve = 6” ( ri of curve = 5.5” ro of curve = 6.5”

Sy (6061 Al) = 78600 psi

length of handle = 4”

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[pic] rn = 5.98957 in

e = R- rn e = 0.01043 in

ci = rn – ri ci = 0.48957in

co = ro – rn co = 0.51043 in

M = F (R+4) M = 3000 in-lb

Compression: [pic] [pic] n = 2.1

Tension: [pic] [pic] n = 1.8

SOLUTION: (1) n (tension) for F = 300 lb n = 1.8

(2) n (compression) for F = 300 lb n = 2.1

REFERENCE:

Shigley, Joseph Edward, and Mischke, Charles R. Mechanical Engineering Design, 5th Edition. Boston: McGraw Hill, 2002. p 91-130.

Appendix E – Bill of Materials

Approved Grant Budget – NCIIA

Level 3

Title The Expedition Walker

Institution Portland State University

PI Faryar Etesami

Grant Period 01/01/2006 – 01/31/2007

Budget Total Total

Item $Requested $Approved

Design, Engineering, Prototyping $4,000 $4,000

Trademark/Patent Expenses $2,050 $2,050

Student Stipends $2,500 $2,500

Travel Expenses $3,000 $500

Total $11,550 $9,050

Bill of Material – Budget Expenditures

Tubular Solutions Inc. $1,890 Steel Bending

Metal Supermarkets $348 6063 Brite Aluminum

Express 3D $386 Rapid Prototyping

Steve Heuer $800 Custom Fabrication

Total $3424

Appendix F – House of Quality

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Appendix G – Detailed External Search

The team researched the market for existing walkers and rollators. Below are a few pictures of the walkers and rollators the team experimented with. These were evaluated for ease of use, comfort, and aesthetics. None of these were found to be completely satisfactory.

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Appendix H – Detailed Internal Search

Below are a few of the conceptual ideas created by the team during the brainstorming process. These were all rejected for various reasons before the final walker design was agreed upon.

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Appendix I– Detailed Concept Evaluation

HIGH PRIORITY

|Criterion |Ease of Use |

|Requirement |Easily Folded |

|Primary Customer |End User |

|Priority |High or 10 |

|Metrics & Targets |Metric |Target |

|Small footprint when folded |Inches |Folded – 33h x 18w x 3d |

|Basis for target selection |Market Research |

|Method of verification |Prototyping |

|Criterion |Ease of Use (Environment) |

|Requirement |Easily Adjusted to fit with the user’s environment |

|Primary Customer |End User |

|Priority |High or 10 |

|Metrics & Targets |Metric |Target |

|Width/Height adjustments |Inches |Width adjustment – 4 |

| | |Height adjustment – 8 |

|Basis for target selection |Market Research |

|Method of verification |Prototyping |

|Criterion |Ease of Use (Environment) |

|Requirement |Easily maneuverable |

|Primary Customer |End User |

|Priority |High or 10 |

|Metrics & Targets |Metric |Target |

|Small turning radius |Inches |Turn radius - 19 |

|Basis for target selection |Market Research |

|Method of verification |Prototyping |

MEDIUM PRIORITY

|Criterion |Safety |

|Requirement |Able to support weight of the user |

|Primary Customer |End User |

|Priority |Medium or 8 |

|Metrics & Targets |Metric |Target |

|Weight capacity |Pounds |300 |

|Basis for target selection |Market Research |

|Method of verification |Prototype Testing |

|Criterion |Safety |

|Requirement |Wheels do not get stuck in cracks, grates, etc. |

|Primary Customer |End User |

|Priority |Medium or 8 |

|Metrics & Targets |Metric |Target |

|Large wheel diameter |Inches |8 |

|Basis for target selection |Market Research |

|Method of verification |Prototyping |

|Criterion |Safety (Ergonomics) |

|Requirement |Ergonomic shocks |

|Primary Customer |End User |

|Priority |Medium or 8 |

|Metrics & Targets |Metric |Target |

|Shocks spring constant |lb/in |200 |

|Basis for target selection |Keen Mobility request |

|Method of verification |Prototyping |

|Criterion |Performance |

|Requirement |Comfortable for long durations of use |

|Primary Customer |End User |

|Priority |Medium or 8 |

|Metrics & Targets |Metric |Target |

|Time |Hours |8 |

|Basis for target selection |Market Research |

|Method of verification |Prototype testing |

|Criterion |Weight |

|Requirement |Lightweight |

|Primary Customer |End User |

|Priority |Medium or 8 |

|Metrics & Targets |Metric |Target |

|Total weight of walker |Pounds |10 |

|Basis for target selection |Market Research |

|Method of verification |Prototyping |

|Criterion |Size & Shape |

|Requirement |Rear Wheel Offset to allow for a wide gait |

|Primary Customer |End User |

|Priority |Medium or 8 |

|Metrics & Targets |Metric |Target |

|Rear wheel offset |Inches |2 |

|Basis for target selection |Market Research |

|Method of verification |Prototyping / SolidWorks Design |

|Criterion |Legal |

|Requirement |No Patent Infringement |

|Primary Customer |Keen Mobility |

|Priority |Medium or 8 |

|Metrics & Targets |Metric |Target |

| |N/A |Unique Design |

|Basis for target selection |Market Research |

|Method of verification |Design Review |

LOW PRIORITY

|Criterion |Cost |

|Requirement |Affordable and within medical allowances |

|Primary Customer |End User |

|Priority |Low or 6 |

|Metrics & Targets |Metric |Target |

|Cost |Dollars |110 |

|Basis for target selection |Market Research |

|Method of verification |Prototyping / Market Research |

|Criterion |Aesthetics |

|Requirement |Attractive with several color options |

|Primary Customer |End User |

|Priority |Low or 5 |

|Metrics & Targets |Metric |Target |

|Color Options |Number of colors |8 |

|Basis for target selection |Market Research |

|Method of verification |Prototyping / SolidWorks Design |

|Criterion |Life in Service |

|Requirement |Should last 5 years with average usage |

|Primary Customer |End User |

|Priority |Low or 6 |

|Metrics & Targets |Metric |Target |

|Time |Years |5 |

|Basis for target selection |Market Research |

|Method of verification |Endurance testing |

|Criterion |Maintenance |

|Requirement |Easy to maintain with average usage |

|Primary Customer |End User |

|Priority |Low or 5 |

|Metrics & Targets |Metric |Target |

|Time between maintenance checks |Years |5 |

|Basis for target selection |Market Research |

|Method of verification |Prototyping / Design Review |

Appendix I – Discovery from the Prototype Process

Keen Mobility was contacted by traveling salesmen representing Minnesota Rubber and QMR Plastics. Keen Mobility suggested that it would be beneficial for the design team meet with the salesmen and discuss exactly what it takes to prototype plastic. Below is a copy of the brochure they provided.

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Appendix J – Albina RFQ Sheet

Albina Pipe Bending Co., Inc. acquires orders via their RFQ Sheet. This is a copy of what the design team sent in to be fabricated.

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Appendix K – Rapid Prototype Material

The design team decided upon rapid prototype models of the handles and feet for cost purposes. Below is a copy of the material data sheet for the material chosen.

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Figure 2 - Traditional Walker

Heavy Duty Walker

Invacare Rollator

Invacare 6219A

Figure 6 - Chosen Walker Design

Figure 10 -Stub End Foot

Figure 12 - Castor Option

Figure 11 - Ball Foot

Figure 1 – Current Rollator

Figure 8 - Key Notch

Figure 13 - Adventure Tip

Figure 3 - Tripod

Figure 4 - Stroller

Figure 5 - Shopping Cart

Figure 7 - Width and Height Extensions

Figure 8 - Top-down view of 2.0 inch base leg extensions

Figure 9 - Ergonomically Correct Handle

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