Up Up and Away
A New Walker Design by The Waka Waka Company
APD2010 – 03
Rohan Agarwal
Shira Bennett
Nancy Lai
Andy Raina
December 14, 2010
ABSTRACT
In the current assistive device market, there are mobility devices that help the elderly walk and there are rising devices that help the elderly stand. The Waka Waka Company is introducing a newly designed walker, the Up Up and Away, which provides both mobility and rising assistance to the elderly population. The Up Up and Away performs these primary functions as well as meets the needs for portability, adjustability, and durability, at a low cost to the consumer. The walker is designed and dimensioned to ergonomically accommodate the physical characteristics of the middle 90% of the elderly population. A prototype and Computer Aided Design (CAD) models have been developed in order to correctly model the dimensions, structure, and important mechanisms. Through market research, and an iterative design process, the Up Up and Away has been designed to meet the aforementioned needs better than the competition. Furthermore, The Waka Waka Company has conducted market and financial analyses in order to develop a business plan that details the outlook of the company’s future.
Table of Contents
1. BACKGROUND 5
1.1 Design Problem 5
1.2 Product Need 5
1.3 Intended Users 5
1.4 Previous Designs 6
1.4.1 Walkers 6
1.4.2 Rising Devices 7
1.4.3 Combination Devices 7
1.5 Preliminary Design Research 7
1.6 Design Objectives 9
2. PRODUCT DESCRIPTION 10
2.1 Concept Generation 10
2.2 Concept Selection 11
2.3. Prototype Evolution 11
2.4 Comparison of the Up Up and Away to Current Assistive Devices 12
3. ANTHROPOMETRIC CONSIDERATIONS 13
4. NOMENCLATURE 13
5. ENGINEERING ANALYSIS 14
5.1 Analysis Model 14
5.2. Engineering Optimization Problem Set-Up 16
5.3. Variable Constraints 17
5.3.1. Weights per Unit Length 17
5.3.2. Angles 18
5.3.3. Handle and Foot Length 18
5.4. Engineering Optimization 19
6. ECONOMIC ANALYSIS 20
6.1 Profit Factors 21
6.1.1. Fixed Costs 21
6.1.2. Variable Costs 21
6.1.3. Revenue 22
7. ECONOMIC OPTIMIZATION 23
7.1 Variables 23
7.2 Constraints 23
8. MARKET ANALYSIS 24
8.1 Market Size Estimation 24
8.2 Marketing Optimization 24
8.2.1 Utility of Design Attributes 24
8.2.2 Calculation of Demand 25
8.2.3 Constraints 25
8.2.4 Results 25
9. FUNCTIONAL DESCRIPTION 26
9.1 Feet 26
9.2. Adjustable Legs 27
9.3. Folding Mechanism 27
9.4. Handles 28
10. EMOTIONAL AND AESTHETICS ANALYSIS 28
10.1. Emotional Design 28
10.2. Proportionality 29
11. SUSTAINABILITY ANALYSIS 29
12. PRODUCT DEVELOPMENT PROCESS 30
13. BROADER IMPACT 31
14. CONCLUSION 31
15. REFERENCES 33
APPENDIX A: PROJECT GANTT CHART 34
APPENDIX B: TEAM ROLES 35
APPENDIX C: USER SCENARIO 36
APPENDIX D: SURVEY 38
APPENDIX E: SURVEY RESULTS 40
APPENDIX F: PUGH CHART 43
APPENDIX G: QFD MATRIX 44
APPENDIX H: ANTHROPOMETRIC MEASUREMENTS 45
H.1 Walker Height 45
H.2 Handle Diameter 45
H.3 Handle Distance from User 46
H.4 Distance Between Handles 47
H.5 Force Supported 47
APPENDIX I: ECONOMIC MODELS 48
APPENDIX J: MACHINING AND ASSEMBLING COSTS 50
APPENDIX K: BILL OF MATERIALS 51
APPENDIX L: MARKET SIZE DERIVATION 52
APPENDIX M: CHOICE BASED CONJOINT SURVEY 54
APPENDIX N: CBC SURVEY RESULTS 55
APPENDIX O: MARKETING OPTIMIZATION RESULTS 57
APPENDIX P: DESIGN FOR THE ENVIRONMENT 60
APPENDIX Q: DESIGN STRUCTURE FLOWCHART 62
APPENDIX R: DESIGN STRUCTURE MATRIX 63
1. BACKGROUND
The motivation for the Up Up and Away was based on a gap in the current market and flaws with current designs. The design concept for the product evolved through consumer research and the development of clear design objectives. The following sections describe the preliminary process from the initial design problem to the final concept selection. The progression of the design and the roles of each designer can be found in Appendices A and B.
1.1 Design Problem
Today, 4.6% of the elderly population uses a walker for mobility assistance. However, there is no device on the market that assists the user in rising from a seated position to a standing position and walking. The Waka Waka Company has designed a new walker, the Up Up and Away, which provides both mobility and rising assistance to the elderly population. The primary design problem was to add the functionality of rising assistance to the walker without sacrificing the performance of other functions such as mobility assistance, portability, adjustability, and durability. The Waka Waka Company also designed the walker to be financially feasible by keeping production costs low and capturing a sufficient market share to ensure profitability.
1.2 Product Need
Many elderly Americans struggle with both walking mobility and rising from a seated position. As shown in the Figure 1 below, there are devices on the current market to assist people with walking and there are devices to assist individuals with standing up, but there are very few devices to assist with both of these physical activities. Since there is not a good combination device on the market which serves as an assistive device to stand up and to walk, people need to buy multiple products for each function. However, it is cubersome to a have separate rising assistive device for every chair, couch, and bed in the home, especially because these devices are typically fixed and not portable. In addition to multiple rising devices, the user would need to buy a device to assist with walking. Buying multiple devices is inconvenient and can become very expensive for the user. The Up Up and Away would solve the problem of these current assistive devices by combining the functions of rising and walking assistance.
Figure 1: There are no options for combined walking and rising assistance in today’s market
1.3 Intended Users
The target consumer for this product is over 75 years of age, and living independently. The user may have trouble with daily tasks, such as driving on their own, but is not living a sedentary lifestyle. Instead, he/she is participating in daily activities, and may require rising and walking assistance to transition between each of these. This is where the Up Up and Away would be of assistance - helping in the mobility transitions required to lead an independent life. The complete user scenario is shown in Appendix C. The answers to the questions posed provide a complete description to the user, and how this user will interact with the product.
1.4 Previous Designs
Currently in the market, there are devices which aid in walking and there are devices that aid in standing up, but there are very few devices that incorporate both aspects into a single device. Many of the current walkers which aid in walking only are not stable enough to help someone into a standing position from a sitting one. The current walkers designed to aid in standing up from a sitting position are usually immobile, because they are attached to the object in which the user is sitting in. The Up Up and Away walker would solve the problem of these current walkers by having the dual function of helping someone to a standing position and also aid in walking.
1.4.1 Walkers There are a number of devices currently on the market to assist individuals with mobility. These walkers can be grouped into four different categories. The first category is the most common version, the standard walker. Standard walkers can be purchased with zero, two, or four wheels, and are adjustable to fit the height of the user.
The second type of walker is the rollator, which is a popular alternative to the standard walker and operates similarly. All rollators have four, large wheels and are equipped with handbrakes and a seat, and, like standard walkers, also fold for ease of storage.
Platform walkers are the third category. These walkers are adjustable by height and include a padded tray with a body cutout. To operate a platform walker, the user places his body weight on the padded platform, grips the handles, and walks normally. Platform attachments can be purchased and added to standard walkers to serve the same function without the full body cutout.
The final category is ambulators, which are a combination of a wheelchair and a walker and are sometimes referred to as enclosed walkers, because the handrail completely surrounds the user. Ambulators also have a built in seat, but unlike rollators, the seat does not fold.
These four types of walkers are shown in Figure 2, below. It is important to note that with all of these devices, there is a tradeoff between increased maneuverability and the need for increased control from the user.
Figure 2 (From Left to Right): Standard Walker, Rollator, Platform Walker, Ambulator
1.4.2 Rising Devices There are a number of devices currently available to assist the elderly in rising from a seated position. Lift chairs and cushions, one of the most popular systems, rotate to a 45-degree angle so that the user can place his or her feet firmly on the floor before standing. While this product helps the user reach the floor, it does not supply support for the actual standing motion. Toilet frames and mount bars are mounted in place and provide the user with a solid support system when standing. Similarly, the CouchCaneTM is mounted to the bottom of a couch or chair and has an oversized handle that the user can grasp to assist with standing. While these devices are useful for standing, they are not portable or versatile. A separate device is needed for each seated location.
1.4.3 Combination Devices US Patent No. 5794639, US Patent No. 5133377, and US Patent No. 4987912 all describe devices that convert the standard walker to a device that assists with rising. This is accomplished through additional legs, retractable wheels, and brakes. While these walkers are not specifically designed to help the user stand up, they are designed to provide the dual functions of stability and mobility.
The only current product on the market serving both the functions of rising up and walking is the Lumex UpRise® Walker, shown in Figure 3, below. This model does not have wheels and is specifically designed to assist users in both walking and standing up from the toilet.
Figure 3: Lumex UpRise®
While it is clear from the above discussion that there are a variety of products available to help elderly users move from place to place and devices that help stand from a seated position, there are very few that combine both functions of walking and standing. In addition, none of the devices that combine rising and mobility assistance are equipped with wheels, a feature that differentiates the Up Up and Away from the competition. As a result, the Up Up and Away fulfils a definite market need for enhanced maneuverability in mobility devices and combines it with the need for portable rising assistance that can be used anywhere.
1.5 Preliminary Design Research
The Waka Waka Company conducted research in order to determine what the target market desires in an assistive device. This research took the form of surveys, observations of current walker users, and reverse design of a current walker on the market. The survey was conducted with 40 students in an Analytical Project Design course. The students were given a standard survey with a choice-based conjoint (CBC) component, and were asked to answer the questions as if they were elderly and needed the use of a walker. The complete survey can be found in Appendix D and the results are summarized in Appendix E.
From the survey results, The Waka Waka Company found that most consumers use their walkers at all times, both in the house and outside, and prefer a walker with only two wheels. The most important secondary features are weight and portability; the majority of consumers prefer the lightest and most easily transportable models. Finally, the survey shows that walkers should be designed for carpet, smooth surfaces, such as tile and linoleum, asphalt, and concrete. In addition to this survey, observations indicated that the elderly who use a walker still rely on human assistance to stand up from a seated position. Also their walkers, while collapsible, occupy a majority of the space in a standard car trunk.
The observations were conducted on current walker users while they walked and stood up from a seated position. The current users used a standard walker with two wheels on concrete surface. The users were able to use the walker to help with walking, however needed assistance with getting up from a seated position from another person.
The reverse design was conducted on the Drive brand Deluxe Trigger Release Folding Walker. This study illuminated a number of areas for improvement. The legs are very difficult to adjust because their push pin locking mechanism requires a great deal of force to operate, shown in Figures 4 and 5. In addition, the Drive model has one horizontal handle on each side, located at the very top of the walker handlebars. The grips themselves are uncomfortable, leave marks on the user’s hands, and are not positioned ergonomically.
Figure 4: Pin Holes on Adjustable Legs Figure 5: Pin for Locking Mechanism
The Drive walker cannot be used to rise from a seated position. When adjusted to the proper walking height, the handles are too high to reach from a seated position. Therefore, it would be impossible for an individual to push up to a standing position. If the user tries to stand by means of pulling, the walker tips. Therefore, the Drive model is not capable of being used as a rising assistant.
Finally, the Drive model’s small wheels get stuck in cracks in the concrete sidewalk. The stoppers on the back two legs are also very rough and transfer vibrations up through the walker into the user’s body. Overall, the Drive walker is very sturdy but has many features with room for improvement.
On a positive note, the Drive walker can be folded to a thin size (as in Figure 6 below) by pulling up on the blue levers. Doing so releases a pin (shown in Figure 7 below), allowing the rails to rotate inwards. To unfold, the user opens the legs until the pin locks in place. Overall, this is a very effective mechanism.
Figure 6: Folds to a Thin Size Figure 7: Trigger Release Mechanism
1.6 Design Objectives
The survey results, observations, and reverse design combine to form the following design problem:
Consumers in the elderly population require an assistive device assist both in moving from place to place and in rising from a seated position. The device must be lightweight, portable, comfortable to grip and use, and easily adjustable to accommodate for varying heights. Furthermore, the device must accomplish all of these objectives in an economical and aesthetically pleasing fashion.
Table 1, below, shows the important design objectives and their metrics. The weights shown are based on both survey results and reasonable design judgments. The functional requirements represent the metrics that will be used to quantify the design requirements and are listed with their target value and unit of measure.