design of an urban wheelchair

School of Innovation, Design and Engineering

DESIGN OF AN URBAN WHEELCHAIR

Thesis Work, Product DesignKPP106, 15 credits, C-level

Master Thesis Programme Innovation and Product Design

Pablo Escudero

Report code: IDPOPEX C:07:132Commissioned by: Own projectTutor (university): Jan FrohmExaminer: Rolf Lövgren,

DESIGN OF AN URBAN WHEELCHAIR - Master thesis workPablo Escudero 2

Abstract

In this report I will develop a wheelchair adapted to the urban reality of our society. It’ll have to compete with the electric wheelchairs on the market today. There is a real necessity on this as the wheelchairs on the streets today have developed little since they were firstly introduced in world war 2.

To achieve a successful product we will study the different wheelchairs and how they adapt to the urban environment. Such study will include several surveys focusing on the user, it’s illnesses and anthropometrical measures as well as his way of usage. Then we will focus on the wheelchair, the types, characteristics, parts, and functions.

The result will be an electric wheelchair which improves significatively in ergonomics, stability and maneuverability over their electric counterparts. Moreover it greatly increases it’s outdoor and indoor capability reducing the architectonical barriers that can be found on a city.


Acknowledgements

I’d like to thank the “Universidad de Zaragoza” and the Mälardalens university to give me the opportunity and support to come to Sweden and be able to do my thesis work on the subject I wanted to.

I’d like to thank my grandfather Vicente for bringing the subject to me, my aunt Ana and Juan Ramón as wheelchair users to give me some insight on the product and it’s uses. To my uncle Santiago to help me with some medical advice. My parents as their support has been invaluable and they sent me all the books I’ve needed to work on my studies.

Last but certainly not least, I have to thank Jan Frohm for his patience, guidance and knowledge about 4 wheelers that has avoided me many problems I’d have got myself into.


Contents

1. Introduction 52. Aim of project 63. Project directives 74. Problem statement 85. Project limitations 96. Theoretical background & solution methods 10

6.1. General description 116.2. Market diagram 136.3. Illnesses survey 166.4. Users of the different wheelchairs 176.5. Figure analysis of wheelchairs 186.6. Functional analysis 206.7. Use analysis 216.8. Ergonomics 216.9. Technical data 226.10. Environment requirements 226.11. Body transfers 23

7. Applied solution procedures 247.1. Concept 1 267.2. Concept 2 297.3. Concept 3 327.4. Concept selection 357.5. Development of the selected concept 37

8. Results 489. Analysis 5910. Conclusions & recommendations 6011. References 6112. Appendix 63

12.I. Foreword 6412.II. Market 6512.III. Ilnesses survey 6712.IV. Users of the different wheelchairs 7812.V. Figure analysis of wheelchairs 8412.VI. Functional analysis of wheelchairs 10412.VII. use analysis of wheelchairs 11012.VIII. Ergonomics 11112. IX. Technical data 11412.X. Environment requirements 12112.XI. Body transfers 123


1. Introduction

During the past decades, new improvements in medicine have increased the life expectancy of the world population. The new medical treatments not only makes life better but also lengthens the period called “third age”. People in their third age tend to get weaker and sicker and they get incapable to perform tasks they were able to do when they were younger. One of their most common disabilities is the atrophia of the lower part of their body. This atrophia reduces their mobility by changing their body posture, by weakening the muscles or by crippling the legs or hips denying their ability to walk altogether. A world map with the live expectancy can be seen on the appendix 12.III at page 66.

To this group we have to add the percentage of the population that is handicapped by some illness and are going to need a wheelchair and the healthy people that are going to get constrained on a wheelchair due to an accident. Therefore we can assume that the need for a wheelchair is far from gone.

The most common wheelchairs found on the streets today are either hand powered or electric powered but they both share the same structure of big wheel on the back and small turning wheel on the front. This layout is very good for sharp turning at low speeds but when it encounters a rough terrain can easily lock the front wheels and dump the seated person. The reason for that is that they are designed to be used in hospitals or in indoors spaces.

There are other kind of wheelchairs that look much like a scooter with four wheels and an office-seat. This wheelchairs, although heavier, they work better outdoors but they are completely unpractical for indoor use. Plus, the effort made to move from one wheelchair to the other and the impossibility to carry both at the same time leaves the user with the dilemma of choosing which wheelchair will suit him best.

Therefore the room both wheelchairs occupy and the economic endeavor of acquiring both wheelchairs reduces the life quality of many of the handicapped people that don’t have the space or money resources needed to get along with both.

Although I’ve never been constrained to a wheelchair myself, in my family Ihave four relatives on wheelchairs. I have had the opportunity to field test them and get first hand information about the everyday life.


2. Aim of the project

The aim of this project is the design of a wheelchair capable of street movement as well as indoors movement. It has to be maneuverable enough to move in a room or tight spaces and able to go over the sidewalks. It will also has to be able to lift the person to a standing position. That means that it has to be a hybrid between a regular wheelchair and a outdoors wheelchair.

PROJECT AIM


3. Project directives

To accomplish the aim of the project some research will be needed.

It’s important to understand key aspects of the product in order to learn the strengths and weaknesses of each type of wheelchairs. It’s also important to find whatever mistake has been done and repeated on previous models. Therefore a survey will be carried out analyzing the different wheelchairs characteristics and differences.

If I limit my survey to only the wheelchairs now in sale I’ll have only studied the solutions given to a problem but I wouldn’t study what the problem is. It could be that the wheelchairs face the problem in a more conventional way and the market inertia doesn’t allow them to rethink and give a better solution. That’s the reason why I’ll conduct a survey about the different illnesses and their relation to a wheelchair. I will look for problems that are solved in an incorrect or incomplete manner and also problems not solved yet.

Many people with illnesses suffer different deformations that prevents them from walking. Some can’t seat properly. I’ll have to study the different ergonomics in two different ways: focused on what the people need and how wheelchairs adapt.

The surveys described above will be basic to solve any kind of wheelchair that is going to be designed. As the project is more focused on a indoors-outdoors solution, a study of the environment will be of most importance. As we live in an urban environment on the common basis I think that a basic survey about the urban environment focused on the difficulties a wheelchair user encounters will suffice.

After studying several aspects of the functionality of the product I have to focus on the form of it. I will have to take a survey on the shapes of current wheelchairs, how and why are like that. It will be interesting so I can decide how the designed wheelchair be understood as a wheelchair but at the same time will stand out from the rest of them.


4. Problem Statements

The problem to solve in this project is:Is it possible to develop a wheelchair that works well indoors and outdoors and that can lift the person to a standing position?

The problem can be solved if the following points are answered:• Requirements for a wheelchair to be indoor capable.• Requirements for a wheelchair to be outdoor capable.• Transition of a handicapped person from sitting to upright position.• Is it possible to find a point in between?

To find the solution more specific questions will be needed in order to find a simple and organized way of solving the project.

• What kind of wheelchairs there are?– Wheelchair market diagram

• What kind of illnesses that involves a wheelchair there are?– Illnesses survey

• How does the wheelchair and the illnesses relates?– Uses of the different wheelchairs

• What do I need to know in order to successfully design a wheelchair?– Figure analysis– Functional analysis– Use analysis– Ergonomic studies– Technical data

• Which problems does a wheelchair user encounter in an urban environment?

– Environment requirements– Body Transfers

• Which kind of wheelchair adapts best to my problem?


5. Project limitations

1. The time limitation for this project is 10 weeks full time.2. The project will be to find an innovative solution for handicap people in urban

environment. It will be centered on the wheelchair.3. It will be presented in 3D-CAD model and physical model4. There is not any kind of material limitations5. The proposal solution should be able to manufacturing in a near future.


6. Theoretical background & solution methods

To successfully accomplish the goals of the project a methodical approach must be used. In this case I'll use the method suggested by Bruno Munari in book reference 4, where the writer suggests an approach to problem solving divided into the following steps:

1. Problem. Here the need is stated. In this report it can be found in the “aim of the project”.

2. Problem definition. Here a more detailed definition of the problem is taken place. In this case it is stated in the project directives, problem statement and project limitations.

3. Problem elements. The problem is divided into smaller problems that can be easily solved individually in such a way that those answers can be gathered to become the solution.

4. Collect data. All needed data to solve the problem elements is gathered.

5. Analyze data. All data collected is analyzed.

Points number 3 to 5 will be answered later in this section and completed in the appendix.

6. Creativity. All analyzed data is gathered and used to solve the problem elements and present viable solutions in a creative way.

7. Materials and technology. A compilation of materials and technology available to solve the problem is presented.

8. Experiment. The elements in point 7 are studied to find the ones that gives the best answer.

9. Models. Study models are created to check if the solutions presented in the creative process are viable.

10. Verify. The models will be checked to see their validity.

11. Constructive drawings. Technical drawings will be made to build the solution.



12. Solution

Due to the project limitations steps 7 through 11 will not be implemented in this report but may be subject to be carried out in the future.

Next I will develop as many surveys as needed in order to be able to generate valid and feasible solutions to the aim of this project. The information gathered for this surveys come mainly from two books (marked as reference books number 1 and 2). The first book, “Problems of wheelchair users in Spain”, is a big research survey centered on interviews on the users: their illnesses, limitations and wheelchairs preferences. This book covers a big part of my research. The second book, “wheelchair user manual”, is a quick guide of tricks and maneuvers a handicap person has to do in order to move around in a wheelchair.

All this information is backed up by a market research through the Internet analyzing most existing models. I interviewed my family too as they have all the different types of wheelchairs in the market and provided useful information on the daily life of the wheelchair user.

First of all I’ll introduce the subject. It will be done by a series of definitions, a market diagram, and a survey about the different illnesses. From there we will analyze the wheelchair to further understand it. There will be a relationship between the different illnesses and the different types of wheelchairs followed by several surveys analyzing every aspect of the product. This section will finish with a study of the urban environment from the point of view of the wheelchair user.

Before starting the survey it will be interesting to go through some definitions. This will give the basic vocabulary needed to properly understand and develop information within this industrial sector.

• (Definition) Wheelchair: A wheelchair is a wheeled mobility device in which the user sits. The device is propelled either manually (by pushing the wheels with the hands) or via various automated systems. Wheelchairs are used by people for whom walking is difficult or impossible due to illness, injury, or disability. ...

en.wikipedia.org/wiki/Wheelchair

6.1. General Description



The concepts behind this definition can be seen on the following table where it shows the overview idea of the ICF (International Classification of Functioning, Disability and Health ), created by the World Health Organization.

• (Definition) Disability: A disability is a condition or function judged to be significantly impaired relative to the usual standard of an individual of their group. The term is often used to refer to individual functioning, including physical impairment, sensory impairment, cognitive impairment, intellectual impairment, mental illness, and various types of chronic disease. This usage is associated with a medical model of disability. The human rights or social model focuses on functioning as an interaction between a person and their environment, highlighting the role of a society in labelling, causing or maintaining disability within that society, including through attitudes or accessibility favoring the majority. Disabilities may come to people during their life or people may be born disabled.



This is a very important table as it easily shows some areas that the wheelchair can improve and areas to take into consideration when working with them. In the first column is shown the physical limitations of the wheelchair user that will need to be taken into account to adapt the design to it’s necessities. On the second column there are the activities that the wheelchair user performs. It’s important to design the wheelchair in order to ease the realization of those activities. The third column are the surroundings factors. Those are the indoors and outdoors structures that allows or refrains the wheelchair from moving around. The forth column centers itself on the personal level. Although it’s as important as the other columns in order to help the handicapped person to have an independent life, it’s so personal that the design of the wheelchair will do little to help and therefore is not a field of investigation in the report.

To get a perspective of new possibilities in the design of a wheelchair it’s important to know what is being produced. Handicap people have many products available to help them gain the mobility they lack. As there are many products that improve the mobility for handicapped people, each in different extend and ability, it’s important to find a way to show them all together. With the use of a diagram it’s possible to outline the different type of products and the solutions given to specific problems.

The Market diagram is meant to show, at a quick glance, the market structure of the wheelchair. It’s divided into to parts: A more broad view where the wheelchair is located between the different alternatives and another one focused only on the different types of wheelchairs.

6.2. Market diagram

This table gathers up all the basic aspects of the disability. The columns are divided into two parts: the first part defines the functioning and disability. This part is also divided into two parts differentiating between body functions and activities. The second group of columns deals with the contextual factors. This one is also divided into two parts separating the factors depending if they come from the environment or from the handicapped person.

The files are divided into three main blocks. The first part displays the different parts that are affected. This includes which domain and their component within they affect to. The second block is formed by the constructs files and manages all the functions that are altered by the parts listed on the first group. The third set of files manages the positive and negative outcomes from the functions of the second block.



Handicap people withwalking / standing problems

Solutions

Walking stickProsthesisWalkers

CrutchWheelchair

In this diagram it’s shown all the different products that helps the handicap person to walk and stand. Although the project is centered on the wheelchair, having a broader point of view can help to find innovative and new ways of transport that can either be adapted to a wheelchair or be completely new, making a brand new segment in this market.



Once centered in the market segment of wheelchairs a more detailed information can be shown. There could be many ways to classify them but I believe the most effective way of doing so is based on the way they are powered. This way we get two very different groups: the ones man-powered and the electric-powered.

Wheelchair

Man powered Wheelchair

Electric powered Wheelchair

ASSISTANT

WHEELCHAIR

STANDARD

WHEELCHAIR

SPORT

WHEELCHAIRVERTICAL

POSITION

WHEELCHAIR

ELECTRIC

SCOOTER

WHEELCHAIR

ELECTRIC

POWERED

WHEELCHAIR

More information about the different kind of wheelchairs can be found on the appendix (section 12.II at page 64)



There are different illnesses that hinders the control over the body and forces the person to use a wheelchair. These illnesses will define the problems and limitations the wheelchair users have and how much their abilities deviate from a healthy person. The design of the wheelchair will have to take into consideration those facts to properly adapt to it’s target user.

To get that kind of information and for it to be relevant a large scale survey is needed. In this case I used the research done in the book “Problemática de losusuarios de sillas de ruedas en España” (Book reference 1) and the e-book “iiplandeaccinparalaspersonascondiscapacidad200320” (e-book reference 2)

There are a some key information to highlight from this survey. A more detailed information can be found on the appendix 12.III at page 66. The different illnesses can be classified into three different groups depending on how limited the person is: they can be limited, severely limited and totally dependent.

The limited people are able to perform most of daily tasks on their own, they have almost normal control over their body and they show very small deformations. The severely limited group can perform many of daily tasks on their own or with the help of another product, they have some control over their body and present deformation on some part of their body. The totally dependent class needs someone else to perform the task for them, have little to none control over their body and have mayor deformations.

The target group to focus the design will be the severely limited as the freedom the product is intended to give will make a difference on that group and if it can help the severely limited it will have no problems to help the ones within the limited class. The project will not be intended for the totally dependent as they will require an assistant to go with them anyway.

6.3. Illnesses survey



Once the different type of wheelchairs and the more relevant illnesses for our project have been stated it will be interesting to see how they both relate in today’s market. This will provide an interesting perspective in two ways:

A – How does the wheelchair adapt to the illnesses’ needs.B – What needs are yet to be satisfied.The point A will give keys to improve the design while the point B will show

untouched market opportunities and more innovative solutions.

As the needs in each group of illnesses is different so are the wheelchair requirements. Useful information can be found by looking at the charts where it shows how a specific wheelchair model adapts to the different illnesses (see appendix 12.IV at page 77). Once all that information has been gathered into a single and more general table where the different types of wheelchairs match the different groups of illnesses, the market picture grows clearer. Most of the wheelchairs on the market today have been designed mainly to satisfy two different groups: the limited and the totally dependent.

The people from the limited group needs a wheelchair with few special requirements therefore they are the easiest group to meet the requirements. Most of the wheelchairs dedicated to them are standard. Being the easiest to build and manufacture, they are able to reach most of the market with little customizations. The wheelchairs adapt very well to their needs.

On the other hand, the people from the totally dependent group have many specific requirements. Those requirements also differs from one illness to another, they requite specialized wheelchairs to fulfill their demands. This groups has severe problems to do normal chores, not only the ones involving movement. This is the reason why they are usually found in the company of someone else that assists them. In this market group the assistant is another important user that needs to be taken into consideration. The wheelchairs in this sector adapt reasonably well.This is shown as most of the wheelchairs in the market are either electric or assistant wheelchairs. This specialized wheelchairs creates a very focused market where only a small amount of units can be sold. Once the product is been placed onto the market there is little outside competence creating a good benefits margin opportunity.

6.4. Users of the different wheelchairs



With most of the products fitting both groups described above, there is little left for the very limited people. This group has to adapt to a wheelchair designed for the limited group, with lower requirements than they need, or the totally dependent, much more expensive and prepared for someone else’s need.

In conclusion, there is a real market opportunity targeting the very limited handicap group. There is a liable technical background to rely on although it will have to be analyzed to find all the aspects that prevents them from getting a perfect fit for the users.

Having studied the user and their needs, the wheelchair market and how both relates has given a good introduction point on the project subject. The next step is to learn about the product itself. Getting to know the wheelchair from different perspectives will provide a good detailed picture of the product and cues that will help the success of a design.

Here it will be analyzed the wheelchair from the figurative point of view: How it looks like, which parts is it made of and what does that shape transmits.

The figure analysis provides useful information on what can be perceive from the wheelchair through pure observation. It’s not centered exclusively on aesthetics but also on how it communicates its functionality and how that is perceived by the user. In order to do that, each wheelchair is seen through three different perspectives: the Syntactic (How does the object looks), the Pragmatic (what it does) and the Semantic (how it tells it’s actions).

After going carefully through all aspects of the wheelchair on the analysis (found on the appendix 12.V at page 83) it is important to note the following information.

From this analysis point of view, standard and lightweight wheelchairs are impossible do differentiate. Both share the shape of a wheelchair recognizable by everyone. The assistant wheelchair differs from the previous two on the back wheel, being smaller on the assistant as there is no need for the person sitting to propel it.

6.5. Figure analysis



All elements of the wheelchair are shaped use oriented. There are no concessions to aesthetics apart than the paint on the metal tubes. As the structure and moving parts are all shown and the wheelchair does perform simple actions, is easy to understand how it operates. All regulations on the wheelchair are made through holes on the support structure and then some screws to hold both pieces at the required length. This simple method is useful when constant changes are needed and the regulation method has to be done often. As most user only need to regulate the wheelchair the first time the use it, it could be interesting to change this rather unaesthetic solution for another one.

The seat is an important part of the wheelchair as the user has to remain on it for long periods of time. As there is some compromise between comfortability and easiness to fold the solutions given are solved on that focus. The seat can be greatly improved by getting a better shape that will allow the user to rest more comfortable while is still able to fold easily.

The footrests, as important as they are they need to be redesigned in such a way that can be stored within the wheelchair easily in case of not use and avoid leaving any protuberances in case of removal.

The aesthetics on the front wheels are very important as they define the “character” of the wheelchair (fast and nimble or slow and cumbersome). On the other hand the focus on the back wheels is centered around the outer ring that may come slippery if wet. The aesthetics on the armrests is important too as it’s designed only with the functionality in mind. It can get some more comfort if it could be adjustable.

Focusing now on the electric wheelchairs we find two different types: the electric-powered wheelchair and the electric scooter wheelchair. The first one is identical to the regular wheelchair with some differences due to the change of propulsion system but the conclusions for this type are the same as the standard. Therefore the following conclusions will be about the electric scooter wheelchair.

As the chair loses it’s need to fold down, the seat can be made rigid with more foam to increase comfort and it can also gain adjustment in some variables. This is highly regarded among the users and helps them avoid atrophy.

The seat in this kind of wheelchairs has to be comfortable over any other function. As the chair gets more rigid the armrest has to be able to fold away. It will also have to hold the controls.



As the footrest can stay on the chair, they will have to look more integrated to the main body. This structure will have to protect the electric system and connections as well as to give the user the ability to open it and perform maintenance on it.

The rims from the wheels along with the plastic cover of the structure will give the most of the aesthetic value to the wheelchair. The electric powered wheels and the turning ones can be placed either front or back. The turning wheels on the back will be harder to learn how to displace and on the front will have to avoid hitting the footrest. The turning wheels can turn car-like or freely with carter forks. The first make a more controlled turn than the second but with a longer radius.

On the functional analysis the uses of each part of the wheelchair is studied. This will allow to know which job is expected of each part and which ones are crucial for any purpose given. With that information some problems can be found like: unnecessary or redundant pieces, functions done by two different parts and therefore likely to be able to merge into one single piece… Moreover, combined with the figure analysis, it is possible to identify if the usability message that a part of the wheelchair transmits has any relation with the function it performs. The detailed functions can be found on the appendix 12.VI at page 103.

There is little more to be said from the standard wheelchairs as the figure analysis gave the same conclusions as all parts are shown and therefore rapidly understandable.

As the electric wheelchair share the same way of configuration as the standard one, most of the pieces share the same functions, with some exceptions: the wheels loses the outer ring and gains an engine, the seat and armrests gain more functions as they loose the capacity to fold and gain in adjustability. Probably the one that has a bigger overall change is the structure as it has to support the weight, give integrity to the product and hold and protect all the electric essentials.

6.6. Functional analysis



Ergonomics can be defined as “the science of obtaining a correct match between the human body, work-related tasks, and work tools.”(www.uchospitals.edu/online-library/content=P01158 ) So we can say that, in this case, ergonomics are a series of parameters that dictates the correct distance between the different parts of the human body and the wheelchair.

The ergonomics study is important not so much for the concept generation process but for the proper design of the wheelchair when sizes will be taken into account. Those sizes, lengths and angles are summarized on a table in the appendix 12.VIII at page 110.

6.8. Ergonomics

The use analysis displays the life cycle of the wheelchair with it’s interactions with all the users. This will help to focus in other areas of usage of the wheelchair, not only on the one related to the user that sits on it. Any improvements in any other area (production, transportation, maintenance,…) will become an advantage over the competition. To see the life cycle of the survey it can be located on the appendix 12.VII at page 109

Looking at the production of the wheelchair, the standard ones are very easy to manufacture, even with low technology equipment. The complex shapes they make and the amount of pieces bent, welded and screwed makes it a slow to manufacture. It could be interesting to study new geometries that speeds up the production system.

During the transportation from the factory to the selling point the most important factor is the ability to stock the biggest number of wheelchairs on the transportations system (usually a truck). As the standard wheelchairs can fold down and has a reduced weight it eases the work to fold an pile. The electric wheelchairs on the other hand is heavier and bigger and can’t fold down, making it more difficult to load and transport.

Use and maintenance on a Standard wheelchair is very simple and a user can find how to do it very quickly and easily. The electric wheelchair on the other hand has more problems than the standard as it has a bigger weight and size, forces the user to work on the garage or outside the house. As all elements are closer to te ground the person doing the maintenance has to lower himself to move the loads (changing batteries or light bulbs for example), getting harder if it’s done by a handicapped person.

6.7. Use analysis



With this section concludes the study on the wheelchair. Therefore it has to cover all the relevant information needed to study and understand a wheelchair that does not fit all the previous analysis. This is then a compilation of facts and numbers. Those wheelchair measures are the ones that are meant to fit with the ergonomic requirements. They are all listed on the appendix 12.IX at page 113.

6.9. Technical data

Once the user and the wheelchair are analyzed it is time to focus our studies on the environment. As the project is named urban wheelchair it is comprehensible that a study of the surroundings and the mobility problems they create is crucial in order to succeed on the design.

It is interesting to look at the table extracted from the book “Problemática de los usuarios de sillas de ruedas en España” (Book reference 1) found on the page 100, where there is a graph showing where each kind of wheelchair is being used most, It can be used only indoors, only outdoors or used in both indoors and outdoors. The results are that at least a 60% of the wheelchair users uses their wheelchair in both cases reaching the 80% on the electric wheelchairs. This is for some reasons: the people that need electric wheelchairs are very likely to be unable to move in any other type of wheelchair due to their illness. The price of the wheelchair is such that a medium income handicap user will only be able to afford one. As the electric wheelchair bar comprises all types of electric powered wheelchairs it’s interesting to see there are some wheelchairs only used outdoors and those must be the scooter electric wheelchairs. The number of electric wheelchairs only used indoors are marginal.

6.10. Environment requirements

only only



Moving around with the wheelchair is an important factor to study, but it is not the only one related to mobility. It is also important to be able to move to and from the wheelchair as the handicap person will have to use the toilet, shower, bed…All those actions must be taken also into consideration to make a good user friendly model.

There are several ways of approaching the transfer, most of them require to be at the same level or at a higher level to ease the process. This works both ways as it’s easy to go from a wheelchair to a chair from a higher point, it’s also difficult if the transition from chair to wheelchair is from a lower position. This means that if the wheelchair is able to change it’s height will help on body transfers.

There are also different directions to approach the transfer. Sometimes it’s better to be side by side or looking towards it. There are pictures that displays the process that is being used today with standard wheelchairs on the appendix 12.XI at page 122.

6.11. Body transfers

This section will be separated into two parts differentiating indoors and outdoors as each present different kinds of problems. The wheelchair user finds many problems when moving around an urban environment, either outdoors or indoors. When indoors the wheelchair user have small area to maneuver either by human traffic or because of excess of furniture.

Whenever outdoors, the terrain gets more complicated. Starting by the surface the surface can be flat and hard as on a sidewalk but may have some small debris that can make the front wheels lock and cause an accident. The ground can also be soft as wet earth on a park or garden making possible for the bike to get stuck. It can also find slopes on the transversal direction he’s heading or uneven terrain making the wheelchair tilt and fall to the ground. Another major problem to encounter while going on the outdoors in an urban environment is when trying to change sidewalks or getting into a building which has a small step in the entrance. Most wheelchairs are not able to solve that obstacle or do it fast.

For a more detailed explanation see the appendix 12.X at page 120.


7. Applied solution procedures

In chapter 7 we will develop 3 different alternatives that will try to solve the problem to move a handicap person indoors, outdoors and to be able to lift them to an upright position. Each one of the alternatives will have their own unique strengths and weaknesses. At the end of the chapter we will chose the one that fit’s best with the requirements given, the information discovered on chapter 6 and the one more creative.

First semester was a trial, no creative thoughts were coming through, I was stuck thinking on four wheels and a chair on top of it. I was designing a rather complex multi-functional go-kart than a proper vehicle for handicap vehicle. At the very beginning of the second semester, my computer crashed down, losing all my project information and forcing me to start from scratch. This new start helped me to view the info with new eyes and get a new perspective. The following concepts are based exclusively on my second semester work.

For this second semester I forced myself to work from a different angle, trying to get the imagination flow going. The name of the project, urban wheelchair, is very strict as it has the name wheel and the name chair that tied me down on the first semester. To maximize creativity I decided to go general again, thinking why a chair, why wheels, what’s the purpose of it all. In easy words: what function does those parts play on the wheelchair?

The answer is easy, to hold and move the user around. With that in mind I tried to explore different ways of holding and moving people around, trying to get them as close to “walking” as possible without creating an exoskeleton robot-like thing.

Lock to avoid falling forward or backwards

Hold to prevent falling

Separate legs from the ground


Some doubts were flowing while thinking, in this case, the stress on muscles for this locking feet system (innovative as it’s not being used by wheelchair today). I consulted my uncle Santiago who is a thraumatologist surgeon specialized on the knees and he assured me the only problem is the need to move as to avoid “Decubitus ulcers“ (more info at http://www.emedicine.com/med/topic2709.htm)

Along with the drawings there will be some important ideas that needs to be taken into consideration and are highlighted with a yellow star .In some parts they are summarized and listed so I typed them down and used the following sign .


To ensure easiness in moving indoors and outdoors I thought that great axle distance will improve stability outdoors but small axle distance will increase maneuverability, making it fitter for indoors. So it would be neat to be able to shift from long axle distance to short and vice versa. Notice how I tried to remove the chair on top of a rigid structure idea.



7.1. Concept 1: Body geometry change

This concept is an electric wheelchair where the axle distance varies. More over, this distance varies with the chair position, lowering the center of gravity as the axle distance grows when going faster to avoid to turn over the wheelchair. It also raised the feet from the ground, making it able to encounter taller obstacles. In a similar way the wheelchair collapses and the person gets raised to a more standing position that allows them to walk around and talk to people from an eye level position instead that from a low sitting position.

To get that, the footrest will have a knee holder that guides the legs and avoids getting them injured. So I studied the movements the chair and the foot rest had to do with each other (section 12.VI) in order to see the viability of the idea as well as to find out if there is a way of doing both movements on a simplified way.



Some important ideas to take into consideration at this stage (related to the work in section 12.VIII) :

the moving bar that repositions the chair has to be as long as the height difference

Front wheel has to be forward than front feet at position 3 (upright position)

Footrest has a different movement ratio

Footrest has to be adjustable in both lengths:

Hips to knee

Knee to feet.

In order to be able to move the chair up and down it will also move forwards and backwards to change the body position to ensure optimal interaction with the environment.



It’s interesting the footrest movement design changes it’s geometry depending on the weight you place on the knee pads, making it engine free and ergonomical with any size and weight of the user.

Raising the seat increases the weight of the legs on the footrests, making them rotate around the knee rest.



7.2. Concept 2: Upside / down

This concept is an electric or manual wheelchair where the axle distance varies. This concept is more “classic” as it has a seat and a rigid structure for it’s wheels. But that’s where similarities end. In here I tried to defy the reason why all the pieces of the wheelchair were placed in such a fashion and if there is any posibility to put them elsewhere improving usage and building costs.

One of the main thing you notice on a wheelchair (section 12.V and 12.VII) is that footrests and front wheels, even when they are so close together they use separate structures with their own folded and welded set of tubes. It could all be part of the same piece.

The way to change the axle distance will be by changing the front wheel distance up to a point it could be used for easy storage. This concept had studied the motorbike-like aesthetics, the position transition and the way the front wheels turn around



One of the key aspects of this wheelchair is that the front suspension system is the one that acts as the lock that changes the axle distance.



7.3. Concept 3: wheelchair pull

This concept is different from the previous ones as it sees the problem from another perspective. This concept is an add-on to a standard wheelchair that powers it an moves it around. It had some issues on it that needed some serious attention as it had to work on a platform already existing with it’s limitations. It’s also cheaper than a whole new wheelchair, making a new type of market opportunity (section 12.II). The information about caster forks have been obtained from “groundwork: casters” (e-book reference 4)

You can’t pass footrests as they are placed now because they leave no room.

You could if you add the footrests to the new system.

If the structure is to low and long it won’t go over bumps.

It has to be small enough to fit UNDER the wheelchair.

If that is so then is NO MORE URBAN CAPABLE than a standard wheelchair.

The bigger the CARTER wheel the less stable it is.

The carter wheel can be placed on the FRONT or on the BACK.

If there is NO carter wheel then a wheel will have to be able to TURN.

It can be big enough to fit INSIDE the wheelchair (or on top).

If that is so then it will have to turn for the wheelchair.

It should be able to REDUCE it’s size for storage.

Place’s to lock on a wheelchair:

Back wheelchair axle.

Front wheelchair arm.

Front wheelchair tire / wheel.

Anti-tip bars.

Folding cross bars.

Arm rests

Foot rests structure (substitute)

The power control will have to be able to attack to the ARMREST



Concept – lateral view with basic structure distribution. To be fitted UNDER the wheelchair.



Concept – lateral view with basic structure distribution. To fit the wheelchair ON TOP

Concept on 3D with the connections and armrest control.

Place to hold onto

the anti-tip bars.


7.4. Concept selection

Although the three concepts explained above suit the requirements of the project, each one will fulfill it to a different extent. Therefore the concept that adapts best will be chosen for further development. To find out we will point their concept strengths and weaknesses and their overall rate of project fulfillment. The results will be presented in a table. Each wheelchair will be tested in a series of aspects. Those aspects will be valued on a scale from 0 to 5 being 0 the lowest value and 5 the highest. The rating will be given by me according to how the aspect is fulfilled by an existing rival wheelchair. In addition to that, each aspect will be added a weight importance as some aspects will be more crucial than the others. The concept with the highest overall value will be elected.

The characteristics valued in the concepts are: outdoor capability, indoor capability, adaptability, raise / lower user, wheel turning, foot rests, electric / hand powered, wheelchair storage. The outdoor capability measures how well it can perform on the outdoors and able to overcome the problems presented on section 6.10. The indoor capability measures how well it can perform on the outdoors and able to overcome the problems presented on section 6.10. Adaptability refers in how well the indoor and outdoor capabilities are complemented. The raise / lower user aspect will determine how efficiently can it raise and lower the user. Wheel turning refers to the turning capacity of the wheelchair, how sharp and precise it’s turning is. Electric / hand powered can only have two different values: 2 points if it can be powered either electrically or manually and 5 points if it can do both. Foot rests considers the holding capacity of the legs and feet, an important factor when raising the user. The last aspect to consider is the storage space it needs when not in use. As the project goal is to get a wheelchair that performs well indoors, outdoors and is also able to lift the person sited, the result on those aspects will be the valued higher.

As some aspects are more important to others, they are related to a weight value. The sum to all the values equals 100. This makes it easier to relate each aspect to a percentage value. As the target wheelchair has to be able to perform indoors and outdoors, the capacity to do so is vital. It’s not sufficient for the concept to perform well on just one. That is why the value of this two aspects is worth 60% of the concept, being 30% each as they are equally important. The adaptability and the capacity of raising or lowering a user are also important as they are related to the main goal of the project. Therefore they deserve to have the same value and having only 40% left to distribute they get a 10% each. With only 20% left to distribute into 4 aspects and thinking that a value under 5% is rating it below it’s true importance, I decided to give the same 5% value to the remaining aspects. Some of this last aspects may seem to deserve more than the value given, like the one that rates the powering method. Indeed the election of making a hand or electric powered wheelchair is very important in terms of manufacturing and the price tag given but what measures is the possibility for an electric wheelchair to be powered manually.



Once all concepts have been evaluated, it’s time to look at the results and make a selections. Concept 1 and 2 are very similar in terms of their outdoor capability and how it adapts to their indoors maneuverability but the first concept does it slightly better. The first concept also is better for indoors the other two. None of the concepts manage to give a good solution at the possibility to raise or lower the user, but concept 1 manages to give a decent one. The concept 3 is a small electric plug in to an existing wheelchair, this leaves to the existing wheelchair do most of the aspects valued, getting a low score for that. On the other hand is the easiest to store due to it’s small size. The next concept easier to store is the concept 2 as it’s capable of folding down. The concept one is too big to be able to get stored easily. The concept 1 is the one that turns best compared to the other two. Although a wheelchair with concept 3 attached will be also able to turn just as good, it doesn’t enhance this ability that’s why he gets such a low score. The concept 2 needs a big turning radius more similar of a bike than a wheelchair, lowering the score. Concept 1 and 2 has an innovative footrest system. Being the first one more innovative than the second, it gets a higher value.

Overall the concept 3 gets a low score as it’s not capable of significantly enhancing the capacity of a regular wheelchair. Both concept 1 and 2 are valid choices but the concept 1 has an edge as its solutions are more refined. Concept 1 has the highest score but what makes it the best choice is that it is the one that performs best indoors and outdoors and gives a feasible solution for raising the user. Therefore I select CONCEPT 1 for further development to make it the solution for this project.

5305wheelchair storage

1,402,253,40100Overall

2525electric / hand powered

0355foot rests

1255wheel turning

01310raise / lower user

13410adaptability

21330indoor capability

13430outdoor capability

Concept 3:

wheelchair pull

Concept 2:

Upside / dow

n

Concept 1: B

ody geom

etry change

Importance value

%




7.5. Development of the selected concept:

At this point we got into more detail. The first and foremost characteristic for this concept to work out is to find out the movement of the chair and see if it’s viable. If we can’t find a feasible solution for this we should go for the next concept discarding this one. We made a more defined drawing of the seat and the footrest. We also cut our own version of a scaled figure in order to articulate it and check if the drawings were satisfactory.



Once we got tested out that the product was able to perform as expected we continued with the design of the footrest and the knee pad. I also studied different ways the swing arm could push the kneepad to make them position themselves with the same mechanical movement (section 12.VIII)



Once we got tested out that the product was able to perform as expected we continued with the design of the footrest and the knee pad. We also studied different ways the swing arm could push the kneepad to make them position themselves with the same mechanical movement



With the chair and footrest solved it was time to place it on our “chassis” and see how we should place the swing arm in order to get the best ergonomic position for the user to perform and where the footrest wouldn’t interfere with the wheels layout.



After this study we decided to go against the swing arm, the signature of the concept, for several reasons:

•It had to be over designed to withstand so much weight.

•Very expensive to build the racks and pinions necessary for it.

•No easy maintenance.

•Could be dangerous if someone places their hand on the wrong place.

•Difficulty to make a strong position, good swing that will allow to get the chair on the desired place without interfering with the wheels.

So we got back to the starting point again for the chassis (keeping all the work done for the chair and the footrest) and came up with two different ideas:

A 3 wheeler were the chair, front half and rear half of the chassis are connected through a pneumatic pump. That means that every time the piston goes up the axle distance contracts and every time it goes down it expands. The back wheels had carter forks and long trail.

A 4 wheeled wheelchair with all 4 wheels able to turn. It reduces it’s axle distance by FOLDING the center of the body with an electric engine rotating along it axle.



Being both options equally viable we decided to go for the one with the folding center as it can work with only an engine and makes a more compact and safe system and it gives a better aesthetics.

Working on the concept we decided to lock the footrest to the chair but instead of doing it at knee height as in the standard wheelchair it’s bolted at feet height. It’s also able to rotate around the foot freely, depending on the pressure given on the knee rest.



After having the basic idea laid out we centered ourselves on reaching the indoors outdoors capability so we studied the differences between having a big or small axle distance as well as the different ways of steering.

Can roll over at a bumpCan get stuck at a bump

YOU CAN GET BOTH ON THE SAME WHEELCHAIR

Good for outdoors

Good for indoors

Good for turning

Good for stability

SMALL AXLE DISTANCEBIG AXLE DISTANCE

Big wheels makes shaky steeringPrecise steering

Cannot be poweredNo shaking

360º turn on a dimeBig cornering radius

Small wheel for high speeds can’t get over bumpsGood at high speeds

CARTER STEERINGCAR STEERING

Options:

Double car steering reduces cornering radius



Front car steering

Back carter steering

Not so stable if carter wheels are close togetherNot so good at turning if the carter wheels are separated

About CARTER wheels:

• axle MUST be vertical

•Lighter wheels

•Big trail

•Big wheels

•Pneumatic wheels require maintenance

Less turn

I decided to have front car steering and back carter steering, I started to draw a more defined product. I soon realized how fragile it looked. Being an object were the user has to use it because of his handicap it has to inspire confidence on him. Therefore I shifted the movement to a mounting type where the engine, instead of folding both ends of the structure, turns a lever around. The lever has one end attached to the front end allowing it to rest on the strong lever and giving a more strong position than the folding type.

Center mounting typeCenter folding type



Looks of the front part.

Front side looked from a back view

Two views of the basic shadows


8. Results

Once all the factors and ideas from the concept development are weighted and added to the wheelchair, the project is defined. The main structure is divided into two well differentiated parts to allow the variation of wheel axle distance to help it perform indoors and outdoors. The front wheels are electric powered and are also capable of turning just like a normal car. The back wheels have carter steering and are free to turn.

The seat is supported by an pneumatic pump capable of withstanding great weight and to move upwards and downwards. The knees rest on a kneepad that is used to regulate the tilt angle of the footrest. All this aspects can be easily see on the following image.


As the result on the survey (section 6.5) demonstrated the main visual message is concentrated on the structure and on the wheels. As the message wanted for this wheelchair was speed and strength the message is sent in different ways:

• The wheels have big rims to give the sensation of a sports car alluding the speed a sport car can get.

• The front part of the structure is shaped resembling the contour of a male strong torso meaning the strength it has within. When the wheelchair folds to reduce it’s size the same message is transmitted as the front body is always on top.

The rear body is shaped in such a way that if it collides with an object it will tend to go over it instead of getting stuck. It also gives a good stable structure to work on and it’s rectangular base helps improve the battery storage capacity.

8. Results


The main characteristic of this wheelchair is the ability to lower and raise the chair and the ability to modify it’s length to fit through narrow spaces. The following two pictures shows how the swing arm moves the front body of the wheelchair onto the rear body making a shorter base. It also displays the positions the chair and footrests take for optimized outdoor travel and maximum height at low speeds respectively .

8. Results

Both bodies are united by a swing arm electrically powered. This arm will force the front body go over the rear body. This swing arm is very sturdy and can withstand a lot of pressure. The engine is a small version of the ones used on the electric beds.


The wheels are the second part of the wheelchair with important visual content. In this wheelchair the front wheels have the looks of a sport cars to give sense of speed. The back wheels have the same style but in a smaller size to reinforce the message sent by the front wheels. The reason why the front wheels are the biggest is also to make easier for the wheelchair to overcome any pothole or curb.

8. Results

The front wheels are the ones electrically powered so they are not able to move freely. They are able to turn just like a regular car would do to make it easier for the user to learn how the wheelchair turns and also to reduce the turning circle.

The back wheels instead they have a carter fork allowing them to turn 360º. This further increases the turning capacity of the wheelchair. This carter fork has a longer trail than normal to make it more stable when turning. It also has a locking system that gradually reduces it’s ability to turn as the speed increases making the wheelchair more stable and predictable at higher speeds.


8. Results

The footrest is integrated into the front body of the structure. They are able to lean back and forth. The way it regulates itself is through the weight given by the user as it rests the weight of the legs on the knee rest creating an angular momentum compensated by the force of a spring.

The way it works is as follows. The footrest system is locked at O allowing only the rotation. There is a spring at O making an angular momentum Ms, that increases as the angle A grows smaller. The leg of the user makes a downward force at W due to the weight. This weight creates an angular momentum Mw at O. Mw depends of W and of the distance between W and O called d. The weight varies depending on the reclination of the seat but for a given position of the seat we can assume that W will be constant.

At any given d there will be a specific A, and therefore a specific Ms. At that same position of d there will be

W

d

O

Ms

Mw

a specific Mw. If Mw is greater than Ms then the kneepad will recline making A smaller, increasing Ms until it reaches Mw’s value. Reaching a stable situation. This case is caused when the person lowers the seat increasing the weight of the legs on the kneepad.

On the other hand if the user wants to raise itself and get more vertical on it’s seating position then the weight W will be reduced, getting Ms bigger than Mw and pushing it until it balances out.

A


8. Results

The footrest are a cavity where the user can rest it’s feet. It’s shape helps keep the heel in it’s place making it hard to move it away involuntarily. The shape reminds the pedals of a car, further increasing the visual message given by the structure.

As the wheelchair is designed to be able to overcome some obstacles, the chair has to be adapted to prevent the user from falling out of it. It’s shape reminds of a cross between an office wheelchair and a car racing seat combining the adaptability of the first with the safety of the second. It has back slightly curved to hold the shoulders of the user a little bit. The seat has high sides to help prevent the user from sliding out of the seat.


The seat itself is mounted on a three spoked metal base. Each radius is separated 120º from it’s counterparts with one of them pointing at the back of the seat. The center is moved to match with the center of gravity of the user. The pneumatic piston head locks onto the chair at the center of this metal base.

The seat has some regulations that are posible. The back can be lowered or raised depending on the height of the user through the button placed on the back (I). The seat can turn around itself (II) to ease the movement in and out of the wheelchair. This movement is only allowed when the armrest structure is lowered (III), making the task easier. When the armrest bar is lowered (III) the armrest folds itself in such a way that always stays horizontal (IV). The system of locking the armrest is similar to the ones found on bus transports. Movements II, III and IV are meant to help the user transfer itself from to the wheelchair (section 6.XI).

8. Results

I

IVIII

II


A physical model was made to represent and ease the comprehension of the product during the presentation.

8. Results

The physical model was a 1/3 scale from aa 3D model with real measures. A more technical view can be seen on the following pages were it will be possible to see .the wheelchair in three different views with some general measurements and a percentile table extracted from the technical data section were it compares actual datum with the measurements of this wheelchair.


8. Results


Electric wheelchairs percentile table.

S1: Full height S2: Full length

S3: Full width S4: Seat width

S5: Height from the front tip of the seat to the floor S6: Seat angle

S7: Seat depth S8: Armrest maximum height

S8*: Armrest width S9: Back angle

S10: Back height S11: Back width

S12: Footrest minimum height S13: assistant’s handle height

S14: Back wheel diameter S15 Front wheel diameter

S16: Distance between both axes

S17: Horizontal Length between the seat’s back and the controller

S18: Height between control and the seat

8. Results


35.5

56.6

60.0

25.0

34.0

100.0

22.0

45.5

106.0

110

10.0

79.5

47.0

17.5

60.0

46.0

64.0

118.5

124.0

p-95

101.6 - 6047.044.0Distance between both axes (cm)S16

45.043.031.0Horizontal Length between the back and the controller (cm)S17

75.073.068.0Armrest maximum height (cm)S8

30.027.016.0Height between control and the seat (cm)S18

31.019.010.5Front wheel diameter (cm)S15

15.032.021.5Back wheel diameter (cm)S14

X93.083.1assistant’s handle height (cm)S13

16.414.08.5Footrest minimum height (cm)S12

45.039.031.0Back width (cm)S11

11289.072.0Back height (cm)S10

10010394Back angle (º)S9

10.08.05.3Armrest width (cm)S8*

38.542.038.0Seat depth (cm)S7

156.2-0.7Seat angle (º)S6

5254.048.0Height from the front tip of the seat to the floor (cm)S5

46.041.537.0Seat width (cm)S4

80.058.553.1Full width (cm)S3

152.3 – 100.5106.077.0Full length (cm)S2

112.995.090.5Full height (cm)S1

Urban wheelchairp-50p-5

8. Results

Notice how the measurements from the front and back wheel diameter are changed as this table considered the back wheel to be the one to be electrically powered. Normal wheelchairs have a range of wheel sizes depending on the user characteristics. The wheelchair designed has a front and back wheel big enough to go over curbs and give stability when at high speeds. It wouldn’t perform better with a smaller wheel and a bigger wheel will only make the wheelchair more expensive.

The seat is just one measure, it could be produced in different sizes to meet all the spectrum of users (as the rest of the companies does).


9. Analysis

Once we finished the development of the concept we now look back to see how well the final product fits into the project requirements. As the aim, the directives, the problem statement and the project limitations are defined, a plan of action is laid and solved through the theorical background and the solution methods.

• The different kinds of wheelchairs on the market are seen on thewheelchair market diagram.

• The kind of illnesses that involves a wheelchair are studied in the illnesses survey.

• The relationship between the users with their illnesses and the different kind of wheelchairs can be seen on the chapter: uses of the different wheelchairs.

• To be able to successfully design a wheelchair I conducted a series of analysis and surveys:– Figure analysis, to understand it’s looks and the visual message– Functional analysis, to learn how it works– Use analysis, to comprehend how it’s used– Ergonomic studies, to analyze how it fits the user– Technical data, to gather useful data for the design process

• To understand more the problems that the urban environment presents to the wheelchair user I analyzed the environment requirements.

• To further the study of the use of the wheelchair within the environment I studied the body transfers as an specific and yet important part of the problem.

The results allowed me to design a wheelchair that adapts best to my problem, to be able to effectively move indoors and outdoors. All the strong points on the desired design have had that goal in mind:

• The Change in axle distance to improve indoors and outdoors movement.

• The height changes to make the wheelchair more stable at higher speeds and to raise the seat to allow the user a better access to the indoor environment.


9. Analysis

• Placing the big drive wheels in front to place the better wheel to face the irregularities of the terrain.

• With carter wheels on the back the turning radius is decreased and performs better indoors.

To be a good wheelchair it also has to perform well in other aspects highly valued by the users as it’s comfort and aesthetics.

• The aesthetics are new in the market, giving it a fresh air but at the same time keeping the positive graphic language from the other electric models to reassure the buyer/user.

• The comfort point of view has been thought through as the wheelchair tilts into comfortable positions and the footrest varies it’s position to adapt to the weight issued, allowing a perfect fit to any user.

The wheelchair concept fulfills all the requirements.


As the analysis shows, my proposed wheelchair has followed a methodicalpath of development. I first focused on the user, analyzing the needs and limitationsthat has the different handicap people. Then I moved on to a deep study of thewheelchair market, learning about the market organization and analyzing the productcharacteristics. Finally I looked over the environment the wheelchair has to move onsearching for the key aspects that will make it overcome with the specific problemsof the urban scenery. With all that information I was capable of producing threedifferent alternatives that met the requirements each one in a different manner. Aftera selection process I chose the concept that would be able to fulfill all the requisitesto make it a successful urban wheelchair.

The solution offered for this project is a wheelchair whose characteristicsmeet the urban requirements found in the problem statement and summarized intothree: to move outdoors, to move indoors and to lower and raise the user. To helpmake the handicapped more comfortable, the wheelchair incorporates a new style offootrest. This footrest prevents the feet from getting out when moving through thestreets. It regulates the position in a natural way, adapting to each user without theneed of an external adjustment. This design, helps achieve a more comfortableposition when combined with the seat. The seat is cushioned in such a way that holdsbetter the user in it's place stopping the body from bouncing over the chair when onrough terrain. The armrests can be lowered and the seat rotates from the central axisif needed to help ease the body transfers. The seat is linked to the rest of thewheelchair through a pneumatic pump allowing it to move up and downindependently. This way the user can from seat on a table to reach higher shelfs.

Unlike regular wheelchairs, the presented model has a two bodies mainstructure allowing it to change it's axle distance, enlarging it to get it more stable onbumpy streets and at higher speeds or reducing it so it can maneuver better in tightspots. The way it changes the axle distance also modifies it's geometry and heightlowering when getting longer and raising when getting shorter. Axle distance is notthe only factor to improve indoor and outdoor movement. The choice of wheels isfocused to support it's movement capacity too. The front wheels have a big radius toabsorb the irregularities of the terrain better. It is also capable of some turningmaking it easy for the user to predict the path and so easier to use. The back wheelsare much smaller and have a carter fork to allow them to turn freely. This makes a much shorter radius of turning for indoor use. With both wheels' turning capacity thewheelchair can turn effectively in very small spaces.

All this innovations and decisions have been implemented through a styledesign that reassures confidence and reliability to the user.

10. Conclusions & recommendations


10. Conclusions & recommendations

This project has had a lot of problems from the beginning. It seemed at first that it was going to be an easy project as the wheelchair concept hasn’t really changed that much since world war two. Reality is that there is a lot of effort put on this market, trying to give the handicap people feasible solutions that will help their lives. As this products are quite expensive is difficult to see if them often on the streets.

As the market grew bigger, it’s necessity to focus the survey grew important. Lot’s of documentation to go through, from technical data, to illness studies and government studies over mobility. Summarizing and taking valuable information out of all that jungle of information wasn’t easy.

Then my computer crashed, leaving me with the job of starting all over again from almost scratch. It was helpful as it allowed me to think about the problem from a new perspective as I already had the data stored on my brain and was being refreshed.

The survey is a summarized work of many other people and can help future students to develop any kind of wheelchair in the near future (if the wheelchair market continues to develop at this rate).

The result of this project is a concept-wheelchair. It’s not a 100% defined and finished product. It has all the innovation and basics on them but it’s kept on a general perspective. Most of the details and mechanisms are thought keeping in mind the possibility of fully development (everything is viable) although it’s not developed to such degree.

When engaging a project as big as this one I will recommend some previous knowledge (maybe having used the product to be designed). I also recommend to focus really fast where the concept is going to aim towards and analyze only in that direction, saving lot’s of time. This project can still go on as a new assignment to another student to finish the definition of the concept up to the last bolt.


11. References

BOOKS:1) Poveda Puente, R. et al., 1998. “Problemática de los usuarios de sillas de ruedas en

España” (Problems of wheelchair users in Spain), IBV, Instituto de Biomecánica de Valencia.

2) Poveda Puente, R., Lafuente, R., Sánchez Lacuesta, J. & Romañach, J., 1998. “Manual del usuario de silla de ruedas” (Wheelchair user manual), IBV, Instituto de Biomecánica de Valencia.

3) Ignacio Serrano, Ana Isabel Serrano, Clara Tamayo & Natalia Simal. 2007. “Proyecto de mobiliario par ala empresa pardo” Universidad de Zaragoza,

4) Bruno Munari, “¿Cómo nacen los objetos?”, GGDiseño, 8th ed., ISBN 84-252–1154-9

E-BOOKS:1) MEYRA. Smart operating manual. MEYRA

http://www.meyra.de/meyraweb/mk_down/BA-9906_eng(205319601)c.pdf

2) Cocemfe: “iiplandeaccinparalaspersonascondiscapacidad200320”No longer available

3) Pushing the limits blog. 2008. http://www.pushingthelimits.com/2008/wheelchairs/top-5-all-terrain-manual-wheelch airs/

4) Groundwork: casters. March 1992. www.wheelchairnet.org/WCN_ProdServ/Docs/TeamRehab/RR_92/9203art2.PDF

During the development of my project all the information as well as my web site directions were lost. Here are the ones I managed to recover.


11. References

WEB SITES:1. The Standard Rules on the Equalization of Opportunities for Persons with

Disabilities http://www.un.org/esa/socdev/enable/dissre00.htm

2. COLUMBUS medical dictionary http://www.columbusneurosurgery.com/MedicalTerms.html

3. St jude children’s hospital medical dictionary. http://www.stjude.org/stjude/hospital/med_terms.jsp

4. UK department of transport, inclusive mobility. http://www.dft.gov.uk/transportforyou/access/tipws/inclusivemobility?page=2

5. MEYRA wheelchairs http://www.meyra.de/meyraweb/o_basis.pl

6. GATE rehab walkrs: http://www.gaterd.se/eng/produkter/?kat_id=87. ETAC wheelchairs. http://www.etac.se/8. INVACARE wheelchairs. http://www.invacare.se/9. OTTO BOCK wheelchairs.http://www.ottobock.se/10. PANTERA wheelchairs.http://www.panthera.se/11. PERMOBIL wheelchairs.http://www.permobil.se/templates/startpage.aspx?id=34312. PERNOVA wheelchairs. http://www.pernova.se/13. VOLARIS wheelchairs. http://www.volaris.se/14. SEGWAY http://www.segway.com/

15. X4 extreme wheelchair. http://www.planetmobility.com/store/wheelchairs/power/vestil/index.html

16. Frontier wheelchair. http://www.vestil.com/wc/frontier.htm

17. TERRA TREK wheelchair http://www.medbloc.com/terratrek.html

18. LIFE EXPECTANCY PICTURE: http://commons.wikimedia.org/wiki/Image:Life_Expectancy_2007_Estimates_CIA_World_Factbook.PNG


12. Appendix

APPENDIX


12. Appendix

12. I Foreword

This is the appendix were there is compiled a wide variaty of information important for the complete understanding of the project.

As you have encountered along the reading of the project, the information related to the subject was referred to be at appendix wasn’t further specified. I did so as the appendix has the same labeling as the chapter 6, so if you are reading the figure analysis on section 6.4, the referred information on the appendix will be found on section 12.IV.


STANDARD WHEELCHAIRFoldable: Yes

Wheel size: Small / Big

Powered: Hand on wheel ring

Environment: Indoor

Characteristics: It may allow movement of the back axle. The front wheel is small and can turn 360º while theback ones are vertical to the ground and are aligned with the seat. In addition they have a ring on the outside so theuser can move them in the direction he/she needs. It can turn over itself. It has stationary brakes to be used by theseated person.

12. Appendix

12.II. Market

ASSISTANT WHEELCHAIRFoldable: Yes

Wheel size: Small / small

Powered: 3rd Person

Environment: Indoors

Characteristics: Similar to the standard wheelchair but with the diference that the back wheel is small and doesn’t have any external ring. The chair have handles on the back of the back of the seat so it can be pushed / pulled by a 3rd person. The brake is placed to be used by the assistant not by the seated.

SPORT WHEELCHAIR

Foldable: no

Wheel size: Small / Big

Powered: Hand on wheel ring

Environment: Indoors or outdoors

Characteristics: They depend on the sport they are meant for. They differ a lot from one sport to another. They are custom built for the user and the sport. They can only be used for one sport only. They don’t have armrests and a small back. They cannot be folded although they are light weighted. The back wheels are inclined inwards so they offer better stability and easier handling of the wheel ring.


ELECTRIC POWERED SCOOTER

Foldable: no

Wheel size: médium / medium

Powered: electric powered

Enviroment: outdoors

Characteristics: This wheelchair has three or tour wheels and the movement is controled by a handlebar. The lowerpart is where the batteries and the engine is located. The bottom resembles a quad.

VERTICAL POSITION WHEELCHAIRFoldable: no

Wheel size: médium / medium

Powered: electric powered

Environment: indoors

Characteristics: It’s basically an electric powered wheelchair with a piston that allows the seat to unfold and lift the user to a straight situation. It has two belts one for the chest and another one for the knees.

ELECTRIC POWERED WHEELCHAIRFoldable: No

Wheel size: Small / Medium

Powered: Electric engine

Environment: indoors or outdoors.

Characteristics: Similar to a standard wheelchair but with smaller wheels on the back. The bottom part of thewheelchair carries the batteries and the engine that powers the back wheels. There is a Small joystick with a fewbuttons that allow the control of the vehicle. This wheelchair no longer has parking brakes but it has a clutch in case it gets low on batteries.

12. Appendix


Although a handicap person in need for a wheelchair can come from a disease (inherited or not) or an accident (making it temporarily or permanent) the following illnesses are the more common reason for a long term wheelchair user.

Hemiplegia AmputationArthritis AtaxiaMultiple sclerosis Forked SpineCerebral paralysis ParaplegiaPoliomyelitis Quadriplegia

This section is important for the understanding of the section 6.2.2. Illnesses restrains.

The following information has been extracted from the book “Problemática de losusuarios de sillas de ruedas en España” (Book reference 1) and the e-book “iiplandeaccinparalaspersonascondiscapacidad200320” (e-book reference 2)

Distributing all this illnesses’ cases through the age scale, we get a percentage division that will help focus the problem through a age-focused point of view:

– Under 18years old: 5%– Between 19 and 30 years old: 27%– From 31 to 65 years old: 60%– Over 65 years old: 8%

The following image shows the life expectancy around the globe to further deepen on the importance of the age factor. Image found on internet (Appendix website number 18).

12. Appendix

12.III Illnesses survey


All this definitions can be found on the book “Problemática de los usuariosde sillas de ruedas en España” (Book reference 1), wikipedia and medical dictionaries online.

• Hemiplegia:is a condition where there is paralysis of one half of a patient's body. Note that hemiplegia is not hemiparesis, wherein one half of the body is weakened but not paralyzed. Hemiplegia is more severe than hemiparesis.

– It can be congenital (occurring before, during, or soon after birth) or acquired (as from illness or stroke).

– It is usually the result of a stroke, although disease processes affecting the Spinal cord and other diseases affecting the hemispheres are equally capable of producing this clinical state. Hemiplegia can be a more serious consequence of stroke than spasticity.

– Cerebral palsy can also affect one hemisphere, resulting in limited function. This does not cause paralysis but instead causes spasms. Cerebral palsy where this is the only symptom is often referred just as hemiplegia.

– Other causes include type 2 diabetes mellitus, which can lead to transient hemiplegia, a type of spinal injury called Brown-Sequard syndrome, and injections of local anesthetic given intra-arterially rapidly, instead of given in a nerve branch.

Having one side of your body totally paralyzed makes imposible por the person to walk or to use crutches. Therefore he needs a wheelchair to sit and move around. The most common wheelchairs for this users are:

– Assistant wheelchair.– Electric powered wheelchair.

12. Appendix


• Amputation: is the removal of a body extremity by trauma or surgery. There are different levels of leg amputation.

– amputation of digits– partial foot amputation (Chopart, Lisfranc) – ankle disarticulation (Syme, Pyrogoff) – below-knee amputation (transtibial) – knee-bearing amputation (knee disarticulation) – above knee amputation (transfemoral) – Van-ness rotation/rotationplasty (Foot being turned around and reattached to

allow the ankle joint to be used as a knee.) – hip disarticulation

People lacking one or both legs are going to need some help to regain their movement capacity. Either by:

– Prothesis, if the severity of the amputation is low (or at least the ankles or knees are operational) and the missing part of the leg can be replaced

– Crutches if there is no leg and therefore he can rely on a crutch to give the support needed.

– Wheelchair (any kind) taking into consideration that both his arms could be healthy and the center weight of the body is changed due to the lack of mass in the lower part of the body.

• Arthritis: Inflammation of a joint usually characterized by swelling, pain, and restriction of motion. The most common are osteoarthritis and rheumatoid. This last one progressively destroy articulations like wrists, elbows, ankles or knees.

• Ataxia: An inability to coordinate muscle activity during voluntary movement, so that smooth movements occur. Most often due to disorders of the cerebellum or the posterior columns of the spinal cord; may involve the limbs, head, or trunk. It is caused by an unknown genetic mutation

It usually starts between 5 and 15 years of age. It’s slowly progressive and irreversible. The process can be between 7 to 20 years long.

12. Appendix


• Multiple sclerosis: A disorder of the central nervous system marked by weakness, numbness, a loss of muscle coordination, and problems with vision, speech, and bladder control. Multiple sclerosis is thought to be an autoimmune disease in which the body's immune system destroys myelin. Myelin is a substance that contains both protein and fat (lipid), serving as a nerve insulator and helping in the transmission of nerve signals.

• Forked Spine: although there are many different variations of forked spine we are going to refer only to the mielomeningocele as it’s the most common. It is a malformation of the spine and it’s spinal cord.

The usual manifestation is a flaccid paralysis of the lower body although it can sometimes have a random combination between flaccidity and stiffness. It can also generate deformation on the spine and legs.

• Cerebral paralysis: permanent disorder of voluntary movement control due to a non-progressive brain damage. It’s caused during the development of the brain (before or after birth) and it ranges between severely handicapped to totally dependent.

Such a demanding illness requires of a self-sufficient wheelchair that the user can use without much movement like the wheelchair (with many add-ons that allows it’s controls) or an assistant wheelchair, in case the handicap person needs the constant help of someone else.

• Paraplegia:Describes complete or incomplete paralysis, affecting the legs andpossibly also the trunk, but not the arms. The extent to which the trunk is affecteddepends on the level of spinal cord injury.

As the impossibility to move both legs the suspect has to be attached to a wheelchair but he may have both arms healthy so he can use any kind of wheelchair.

• Poliomyelitis: An acute viral disease usually caused by a poliovirus and marked clinically by fever, sore throat, headache, vomiting, and often stiffness of the neck and back; these may be the only symptoms of the minor illness. In the major illness, which may or may not be preceded by the minor illness, there is central nervous system involvement, stiff neck, pleocytosis in spinal fluid, and perhaps paralysis; there may be subsequent atrophy of muscle groups, ending in contraction and permanent deformity.

• Quadriplegia: paralysis of all four limbs. It’s also known as tetraplegia. Indicative of spinal cord injury in the upper cervical area. May be acute or gradual in onset depending on the nature of the lesion.

12. Appendix


12. Appendix

We will now focus our study in illnesses on the ability or control over the body and the wheelchair of choice for each case. This will enhance our comprehension of the adaptability of the wheelchair to the user and it’s limitations in the use of a wheelchair.

The following information has been extracted from the book “Problemática de los usuarios de sillas de ruedas en España” (Book reference 1)

All illnesses studied except one have over 2 out of 3 points on arm mobility which means it is between moderated and full mobility.Average on arm mobility:Assisted wheelchair – 2.00Standard wheelchair – 2.51Electric wheelchair – 2.10

If you measure instead of mobility sensitivity on arms you get that the average is over 2.5 out of three.

This means that most of the wheelchair’s user population can actually use standard ones. Also the most restrictive illnesses requires a third person for taking care of the patient making the assisted wheelchair the best option available.

Sensitivity is high in all cases meaning that maybe a handicap person with insufficient arm mobility to power a standard wheelchair is still able to effectively control a joystick from an electric wheelchair.

We will now have a look at the control over the torso (table 12.III.a). This ability is very important because it explains the self capacity of the handicapped person to control his torso and not lean forward, backward or sideways accidentally. It also helps the person to avoid sliding down the chair.

People with amputated legs have to move on a wheelchair but otherwise are normal people and so most of them have no problems at all with their torso control. Including the amputated, 67% of the people have little problem with torso control, while those that have less control are the ones with lateral or multiple sclerosis.

Range being:

0: Totally dependent 2: limited

1: Severely limited 3: normal

Average on Torso control:Assisted wheelchair – 1.35Standard wheelchair – 2.09Electric wheelchair – 1.59

Range being:




12. Appendix

Seeing how different handicap people control their torso we will look now at how good is the control of the users of the different wheelchairs.

As we saw earlier most of the people have good torso control and those end up using a standard wheelchair while the ones with more difficulties have to rely on electric wheelchairs. The most dependent people rely on a assisted wheelchair as they need someone else to place them properly on the chair as they can’t avoid to fall down from it.

Several illnesses suffer deformations that prevents them from walking since youth, others are forced to get into a wheelchair and their body gets deformed as they spend so much time sitting and not standing (specially if the person hasn’t grown up yet).

Most of the illnesses show deformation of some kind (table 12.III.b), being the amputated people the ones with less deformation (only 8% presented deformation on the back). The less deformed part of the body in all the illnesses has been the neck while the back is the most deformed one with half of the people surveyed presented some level of deformation. Knee, hips and feet share the 66% of the deformation (22% each) and it’s found quite even being always the feet the most deformed one as it grows deformed for bad postures due to a lack of control over them. Only arthritis and multiple sclerosis have higher rate of deformation on the knee over the feet. The illness that has the most deformations is cerebral paralysis

Once we have a clear idea of how affects each illness to the overall capacity of the handicapped person we are going to focus on how does that affect their daily life (table 12.III.c). Although the average for the daily chores are quite high, many are severely limited. Amputation is still the most self-sufficient with the people with forked spine, paraplegia and poliomyelitis while lateral and multiple sclerosis, cerebral paralysis and quadriplegia are the most limited. Most of the illnesses are able to perform quite well with bed chores and their feeding capacity while most struggle really bad on body transfers.

Average on Torso control:Assisted wheelchair – 1.35Standard wheelchair – 2.09Electric wheelchair – 1.59

Range being:




•Torso controlResults in %

14202740Total

21323018Quadriplegia

1361963Poliomyelitis

22262230Cerebral paralisis

2113451Paraplegia

18132346Miopatía

9361836Hemiplegia

25332219Multiple Sclerosis

44251319Lateral Sclerosis

3-2671Forked spine

5294126Ataxia

3103652Arthritis

--2080Amputation

DependentVery limitedLimitedNormalIllness

The percentages are related to the number of cases in each illness. The green background are the most featured value within the illness.

12. Appendix

Table 12.III.a


This information has been extracted from the book “Problemática de losusuarios de sillas de ruedas en España” (Reference 1), and can be found on page 72.

•Deformation of body partsResults in %

49162222227Total

339148114Quadriplegia

813262516-Poliomyelitis

603638333622Cerebral paralisis

384111376Paraplegia

661119361310Miopatía

3695914-Hemiplegia

253113253Multiple Sclerosis

31132531256Lateral Sclerosis

7228334323-Forked spine

681522371510Ataxia

412522314212Arthritis

8-----Amputation

BackPelvisHipsFeetKneeNeckIllness

The percentages are related to the number of cases in each illness, so for example 12% of the people with arthritis has neck deformation and but only 7% over all the people surveyed has it. The value doesn’t have to go up to 100% as the same person can have more than one deformation.

The ones on black background are the most important ones with the deformation. While the ones on green are the most featured within the illness

12. Appendix

Table 12.III.b


This information has been extracted from the book “Problemática de los usuarios de sillasde ruedas en España” (Reference 1), and can be found on page 74.

•Bed: to get up, to get down, moving in bed and control over the sheets.

•Dress: How to dress up or down (upper and lower half), to put on/off the shoes, tie the laces, use of buttons, zippers or fasteners.

•Hygiene: To bath or shower, use the toilet wash upper and lower half of the body and other activities like shave, brush teeth…

•Feeding: Hold and use cutlery, mugs, glasses, serve food to oneself, cut meat, to spread butter on a slice of bread…

•Transfers: to bed, to toilet and to a vehicle.

•Easiness for basic activities

12. Appendix


From 0 to 3

0.82.01.72.41.81.92.1Total

0.71.41.32.01.11.11.5Quadriplegia

0.52.82.62.92.72.82.8Poliomyelitis

0.81.41.21.61.21.31.6Cerebral paralisis

0.42.72.52.92.52.82.8Paraplegia

0.91.81.52.31.71.61.8Miopatía

0.71.81.52.41.81.42.0Hemiplegia

0.71.61.32.11.51.51.8Multiple Sclerosis

0.91.31.31.21.11.21.5Lateral Sclerosis

0.42.62.53.02.42.62.7Forked spine

0.91.81.22.21.81.82.0Ataxia

0.71.81.22.51.51.42.2Arthritis

0.62.52.33.02.02.32.8Amputation

Global deviation

Global average

TransfersFeedingHygieneDressBedIllness

Average Basic activity:Assisted wheelchair – 1.13Standard wheelchair – 2.09Electric wheelchair – 1.61

Range being:

0: Can’t do it himself

1: Can do with someone else’s help

2: Can do with technology help

3: can do it by himself

12. Appendix

Table 12.III.c


12. Appendix

Quadriplegia

ElectricLightweightStandardIllness

Total average

Poliomyelitis

Paraplegia

Cerebral paralysis

Forked spine

Multiple sclerosis

Ataxia

Arthritis

Amputation

In the use analysis we will study how each wheelchair adapts to each kind of illness. It’s a different point of view than in the previous point where we saw what wheelchair was used by each illnesses. This way we will find if the wheelchairs hit their target market or not.

The Following table has been produced with the info from the tables on the appendix averaging the results for the Standard an Lightweight wheelchairs. The electric wheelchair values, as not given by the companies, have had to be given a weight value taking in the consideration the limitations of the different illnesses and the way the wheelchair enhances their movement ability. I’ve based the values on the tables of the section 6.2 and the descriptions of the models.

As this table is an average of other tables, values don’t get over 3 although 5 is the top score. Because the information is been taken from the different manufacturers’web pages, not all model have the table and they don’t use all the same scale. Therefore it can only be used as a guidance.

Looking at the table values from 6.2 and comparing their high values to the ones in this table we can see there is a correlation between them. So we can see that the wheelchairs on the market are properly designed for their users AND users understand it too.

12.IV Users of the different wheelchairs

Table 12.IV.a


Meyra 3600• In hospitals, clinics and care centers

as transport and pushing aid• In domestic use for short term, not

permanent use for people that have remaining mobility

• As a basis for special constructions

Standard wheelchair

Results extracted from MEYRA, Otto Bock and Pantera wheelchairs’webpage.

Otto Bock Avantgarde T

Very goodbad

Quadriplegia

Poliomyelitis

Paraplegia

Cerebral paralysis

Forked spine

Multiple sclerosis

Ataxia

Arthritis

Amputation

Very goodbad

Quadriplegia

Poliomyelitis

Paraplegia

Cerebral paralysis

Forked spine

Multiple sclerosis

Ataxia

Arthritis

Amputation

12. Appendix


Otto Bock Avantgarde Ti Ultra

Otto Bock Avantgarde VR

Very goodbad

Quadriplegia

Poliomyelitis

Paraplegia

Cerebral paralysis

Forked spine

Multiple sclerosis

Ataxia

Arthritis

Amputation

Very goodbad

Quadriplegia

Poliomyelitis

Paraplegia

Cerebral paralysis

Forked spine

Multiple sclerosis

Ataxia

Arthritis

Amputation

12. Appendix


Otto Bock Voyager

Meyra Eurochair• Full equipment chair for long term

provision in permanent everyday use• Well suited for provision of many

disabilities with a high variety of adjustments

• In rehabilitation clinics to achieve therapeutic goals

Lightweight wheelchair

Very goodbad

Quadriplegia

Poliomyelitis

Paraplegia

Cerebral paralysis

Forked spine

Multiple sclerosis

Ataxia

Arthritis

Amputation

Very goodbad

Quadriplegia

Poliomyelitis

Paraplegia

Cerebral paralysis

Forked spine

Multiple sclerosis

Ataxia

Arthritis

Amputation

12. Appendix


Meyra Eurochair HEMI• Individually adapted first provision

after stroke• For users who propel themselves

with their feet (e.g. hemi, MS, craniocerebral injury, geriatrics)

• Constant provision with adjustment possibilities to functional changes

• As therapy equipment in rehabilitation or at home

Very goodbad

Quadriplegia

Poliomyelitis

Paraplegia

Cerebral paralysis

Forked spine

Multiple sclerosis

Ataxia

Arthritis

Amputation

Otto Bock Start M3Very goodbad

Quadriplegia

Poliomyelitis

Paraplegia

Cerebral paralysis

Forked spine

Multiple sclerosis

Ataxia

Arthritis

Amputation

12. Appendix


Otto Bock Start M5 ComfortVery goodbad

Quadriplegia

Poliomyelitis

Paraplegia

Cerebral paralysis

Forked spine

Multiple sclerosis

Ataxia

Arthritis

Amputation

Meyra Electric Champ• Outdoors: safe traction thanks to

good rear wheel suspension and broad tyres

• Indoors: easy to manoeuvre through compact chassis with integrated anti-tip device and central seating position

• Optimal support for long-term sitting as well as pressure relief through seat tilt and back adjustment

Electric wheelchair

12. Appendix


Meyra Electric Champ Lift• For indoor and outdoor use• The lift function increases

independence - racks and closets can be reached again

• Easier frontal transfer with negative seat tilt setting

• The compact chassis increases mobility and independence in everyday life

Meyra Electric Clou• Easy to transport, easy to fold• For people with little functional

changes and sufficient torso stability• Suited as a transport aid for

temporary implementation

Meyra Electric Optimus 2• Ideal for frequent outdoor travelling,

also on uneven surfaces• Ensures extreme safety in traffic and

effortless mastering of higher inclinations

• For the daily trip to work or for shopping

12. Appendix


12. Appendix

In the figure analysis we will describe the structure and connotation of the different parts of the wheelchair. We will study it from the general to the specific defining in every moment three aspects of the figure communication: Syntactic, Semantic and Pragmatic.

The Syntactic explains how the object looks, it’s physical description. The Semantic explains which message does it transmits and the Pragmatic explains how does the message gets sent.

This analysis is important as it explains the product’s language and also gives cues to understand it and allow an easy learning of it’s use. It will also allow the buyer to identify the wheelchair that rapidly adapts to their needs. Getting the wrong message can deliver a wrong perception of the product. The following tables are an overall view of the wheelchair, having a more detailed view of each part on the appendix.

Back

Standard wheelchairs.

Seat

Armrests

Structure

Back wheels

Front wheelsFootrests

Brake

12. V Figure analysis of wheelchairs


12. Appendix

Parking brake to avoid the wheelchair

to move when stationary

Hand operatedIt can pivot

It will prevent the wheel from moving

Plastic handle with a cylinder finish at the

other end at 90ºBRAKE

Holds the feet in position and away from the ground or

the front wheels

They can hold weight

Feet wont slide off

Rectangular plastic pieces on a metal tubular structure

FOOTRESTS

Give stability and the ability to turn the wheelchair on

the spot

They can turnThey roll

Small wheels without spokes

mounted on a metal structure

FRONT WHEELS

Give stability and power the wheelchair

It rollsIt can be pushed

It’s light

It’s circularMetal outer ringVery thin spokes

BACK WHEELS

It holds and places all components of

the wheelchair

can stand weightCan collapse to use

less spaceIt’s adjustable

Metal tubes welded and drilled on a

scissors like shapeSTRUCTURE

Place to rest your arms

Protects you from hitting the back

wheels

You can rest your arms on top

It’s rigidIt can’t be moved

A metal and plastic structure with a soft top made of cloth

ARMRESTS

Place to sitIt’s softYou can fold it

Cushioned rectangle made out of cloth on a horizontal position

SEAT

Soft surface to lay your back in

comfort

It’s soft It can be folded

Cushioned rectangle made out of cloth on

a vertical positionBACK

PragmaticSemanticSyntacticObject


Arm rests

Cushion

Structure

Hand Protector


Prevents the hand or clothing to get stuck in the rear wheel

It’s lightIt’s not

trespassable

Thin plastic rectangle on a

vertical positionHand Protector

holds the hand protector and the cushion in place and locks into the

wheelchair structure

It’s resilientIt’s light

Bent tube on a U shapeStructure

Small surface to rest the forearmsIt’s soft

It’s hard to rip

Leather-covered foam on a

rectangular shape with round edges

Cushion

12. Appendix

The armrests are there to perform basically two tasks: to protect the user from having accidents with the back wheels and rest the arms when not moving the rear wheels. It is an important part of the wheelchair that increases comfortability and safety. The models studied have non regulable armrests as they are built just looking on the easiest, cheapest way to fulfill the function.


Back wheels

Tires

Rim

Outer ring

Axle

Spoke


It’s used to power the wheel by means of pushing it with a hand

It can be grabedIt’s light

It’s locked to the rim

Tubular hoop made of metalOuter ring

It’s the connection of the wheel and the wheelchair structure

Holds the weight load of the wheel.

It’s sturdyIt can turn around it’s center line

Thick metal cylinder Axle

Holds the axle in the center and reinforces the integrity of the whole

wheelIt’s lightThin metal tubeSpoke

metal structure thatholds the rest of the components of

the wheel


Metal hoop with a U shape and holesRim

It’s the soft part of the wheel that stays in contact with the ground

It can rollIt’s soft

It has grip

Circular shape Texturized rubber hoop with a inner

tube

Tires

12. Appendix

As for the back wheels they are simple bike wheels. This helps understand better not only the functionality but also the maintenance that they require. Both wheels are independent from each other and allows them to move freely from one another. The biggest difference the back wheels have with their bike counterparts is the outer ring used for propelling the wheelchair. Being a smooth metal tube can present some problems when wet (due to rain or sweaty hands).


Skeleton

Footrest holder

Back wheel axle

Structure

Folding Axis


Circular tubes welded to the skeleton

Connected by a screw

It collapses in the horizontal axleIt strengthens the skeleton

Two metal tubes connected in the center by a screw

Folding Axis

Small surface where the footrests gets attached

It wont break easilyIt can hold little weight

Drilled metal plate welded to the

skeleton

Footrest holder

It’s where the back wheel gets attached and allows it to

turn.

It’s reliableIt has attachments

Short Tube solidly united to the

skeleton

Back wheel axle

It’s the backbone of the wheelchair where

everything is attached to

It’s sturdyIt has attachment points

It’s rigid

Painted metal tubes welded and drilledSkeleton

12. Appendix

The wheelchair is built in such a way that the main frame is built by two identical structures united by two axis articulated between them that allows the wheelchair to fold down to save storage space or ease the transportation when not in use. The rest of the elements are attached to this frame. The combination of folded metal tubes compose a simple, effective, light and resistant solution that inspires confidence on the user. In this basic skeleton for the wheelchair there are many protuberances that sticks out, all of them to install basic elements. One of those are the rear wheels. There are two basic types of back wheel axle: those that are solid from one end of the wheelchair to the other, and those that are just the endings of the axle, welded at each side of the wheelchair. The first type is commonly used on sport wheelchairs as they need to have it reinforced as they turn and change directions quite fast. The second type is used on the standard and lightweight wheelchairs, it reduces weight, looks lighter and allows the wheelchair to fold although it looks weaker.


Caster fork

Wheel

Front wheels

Tyre




It has grip

Textured rubber hoopTire

Connects the tire to the caster fork. It also holds all the weight load of the

wheel

It’s sturdy and light

It can roll

Plastic hoop with built-in spokesWheel

Holds the wheel and allows it to turn freely 360º

It’s smallIt’s light

It can turn

U-shaped plastic pieceCaster fork

12. Appendix

The front wheels are the ones responsible for the turn in a Standard wheelchair. The rim and fork of the wheel can alter dramatically the aesthetic of the wheelchair. It can look faster and lighter or slower and heavier. It needs some practice at the beginning to learn how the front wheels reacts as they have a different feel when turning than any other system used before by the user (bikes, cars, etc.) but it doesn’t take long to master it.


Footrests

Structure bar

Leg strap

Foot plate


It’s where the foot rests. It can be folded away to ease the movement into/out of the

wheelchair

They are a pair They can be used individually

Prevents the feet from touching the floor or

touching the front wheelsIt can be folded away

Easy to get the feet in or out

Plastic surfaceFoot plate

It lets the legs rest and prevents the leg to go backwards and hit

the front wheelsIt can be taken away

It’s flexibleIt’s confortableIt has a velcro

Strip of fabric Leg strap

It supports and connects the foot panel to the wheelchair’s

structure. It can be taken apart

It’s an attachmentIt can be folded

Can be regulated in lenght

Bent circular tube, drilled and with another tube

withinStructure

bar

12. Appendix

The footrests are an important part of the wheelchair as the user needs to hold his feet above ground level for the wheelchair to move. The footrests are also detachable or removable so the user can step into ground for: getting an anchor feeling and to get a solid point of support when he decides to step off the wheelchair. In the standard wheelchairs the footrests are able to be folded away and completely removable. The reason they are foldable is for the user to step off the wheelchair. The problem with the footrests is when they are completely removed. In that situation there is no place to store them. They also leave the footrest’s holder protuberance in the wheelchair unused. This protuberance can get in the way or get stuck and brakes the aesthetics of the product.


Assistant’s handle

Back structure

Back

Soft back


Soft surface to lean your back against

It’s flexibleIt’s soft

It can be foldedIt can be separated

Cushioned fabricSoft back

Very simple and light structure to hold the soft back on it’s place

It’s lightIt’s part of the wheelchair’s

skeleton

Folded painted metal tube Back structure

A third person grabs them to push or pull the wheelchair

It’s nice to holdYou can apply

force to it

Soft plastic tube with an ergonomic

shape Assistant’s handle

12. Appendix


Soft seat

Seat structure

Seat


Very simple and light structure to hold the soft seat on it’s place

It’s lightIt’s bolted to the

wheelchair’s skeleton

Straight painted metal tube bolted to

the wheelchair’s skeleton

Seat structure

Soft surface to sit on

It’s flexibleIt’s soft

It can be foldedIt can be separated

Piece of fabric with a plastic foam cushion insideSoft seat

12. Appendix


Handle

Swing arm

Brake joint

Brake

Brake pad


Folded metal plate that connects the brake pad with the brake joint

It’s a moving partIt’s remotely

activated

Folded metal plateSwing arm

Plastic piece placed horizontally that blocks the movement of the rear

wheelIt’s rigidPlastic cilinderBrake pad

Connection between the handle and the swing arm

It’s sturdyIt transfers

motions

Triangular metal plate with screws

and boltsBrake joint

Place where the user activates the brake

It’s a moving partHave to hold it

and push or pull

Plastic handle to push or pull on a vertical position

Handle

12. Appendix


Electric wheelchairs.

Back

Seat

Armrests

Structure

Front wheels

Footrests

Safety brake

Back wheels

12. Appendix


Parking brake to avoid the wheelchair

to move when stationary

Hand operatedIt can pivot

Plastic handle with a metal tube that goes

into the structureSAFETY BRAKE

Holds the feet in position and away from the ground or

the front wheels

They can hold weight

Feet wont slide off

Rectangular plastic pieces on a metal tubular structure

FOOTRESTS

Give stability and pulls the wheelchair

They are poweredThey roll

Medium-sized wheels with plastic

rims and fixed to the front

FRONT WHEELS

Give stability and the ability to turn to

the wheelchair

It rollsThey can turn

It’s light

Medium-sized wheels with plastic

rims.BACK WHEELS

It holds and places all components of

the wheelchair

can stand weightHides al internal

components

Metal structure within a plastic shellIt also holds all the electric components

STRUCTURE

Place to rest your arms

Protects you from hitting the back

wheels

You can rest your arms on top

It’s rigidIt can’t be moved

A metal and plastic structure with a soft top made of cloth

ARMRESTS

Place to sitIt’s softYou can fold it

Cushioned rectangle made out of cloth on a horizontal position

SEAT

Soft surface to lay your back in

comfort

It’s soft It can be folded

Cushioned rectangle made out of cloth on

a vertical positionBACK


6.4. Figure analysis of wheelchairs


Electric controls

Structure

Arm rests

Cushion


It’s the control of the electric system of the wheelchair: lights, speed, direction. Is all

controled through this pad.

Joystick is used to control the movement Buttons

are for secondary optionsrelated to movement

Buttons just need to be touched to activate them.

Ball on top of a stick placed on topof a plastic case ofrectangular shapewith buttons on

it’s top side

Electric controls

Supports the cushion and gives a platform to place the electric controls

Allows to move it away to make the way in/out easier


It can moveIt has some controls

Several metal squared-profiled

tubes that are articulated

Structure

Small surface to rest the forearmsIt’s soft

It has gripIt’s comfortable

Cushioned rectangle made out

of cloth on a horizontal position

Cushion

12. Appendix

It also has an armrest like the ones found in an office chair. Compared to the one found on a standard wheelchair there are many differences: first is the electric control panel where the user control the wheelchair movements, it’s easy to use and remember once is explained although with some practice the user can learn to use it too. The armrest can move up and down so it can ease the exit of the wheelchair. As it only has support on one of the sides it also looks lighter and it does not need the hand protection as the wheels are far away down from the seat.


Lordosis adjustment

Recline angleAdjustment

Back

Cushion


Allows the back of the seat move it’s center outwards or

inwards

It can turnIt’s hand operatedIt’s related to the

middle of the back

Round disk with a wavy outer line

Lordosis adjustment

Allows the back to change it’s relative positioning angle with

the seat

It can be pushedIt’s hand operated

It’s related to the back and the seat

Lever connected to a round disk

Recline angle

adjustment

Large surface to rest the backIt’s soft

It has gripIt’s comfortable

Cushioned rectangle made out of cloth on a vertical positionCushion

12. Appendix

One of the bigger changes on this model is the seat. Without the need to fold the wheelchair to reduce space the seat can get more foam and become more comfortable. It resembles an office chair. There are many variables that can get adjusted like the angle between the seat and the back, how tilted the chair is or the curvature of the back.


Footrest structure

Footplate

Footrest

Leg strap


It’s where the foot rests. It can be folded away to ease the movement into/out of the

wheelchair

They are a pairPrevents the feet from touching the floor

or touching the front wheelsIt can be folded away

Easy to get the feet in or out

Plastic surfaceFootplate

It lets the legs rest and prevents the leg to go backwards and hit

the front wheelsIt can be taken away

It’s flexibleIt’s confortable

Strip of fabric Leg strap

Metal structure to hold the rest of the footrest parts

It’s strongIt’s reliable

Bent metalictube

Footrest structure

12. Appendix

The footrest is the same as the standard except it just folds away to ease the access to the ground. On the contrary than on a standard wheelchair, the footrest does not come off completely. Some models have it integrated into the structure making it impossible to remove.


Tire

Front wheels

Rim

Connects the tire to the engine. It also holds all the weight load of the wheel

It’s sturdy and lightIt can roll

Metal hoop with built-in spokesRim


Holds the rim in it’s place connecting it to the main chassis.

It can turnIt’s removable

It’s for holding two pieces in place

Round cilinderwith a marking in

it’s top center

Connection screw



It has grip


tube

Tire

Connection screw

12. Appendix

The front wheels in this wheelchair are the powered ones. As they can’t turn there is no problems with the footrests and any involuntary hits. The wheel has an electric engine and a magnetic brake to control de movement. The tires are thick to absorb vibration and also transmits some off-road capability. The metal spoked rims give it a sporty and quality finish.


Tire

Suspension

Back wheels

Rim

Direction engine

Shaft cover

Drive shaft

Connection screw

12. Appendix

The back wheels are the turning wheels. The wheels themselves are identical to the front wheels. Being the turning point in the back of the wheelchair makes it more difficult to learn how to move around with it than it would be if the turning wheels were up front. The wheels have a set of suspensions to ease the ride. The turning capability is electrically controlled, giving the turning capacity of a car. This means it has a larger radius for turning than the standard wheelchair with it’s caster forks, making it impossible to turn on very reduced spaces on the other hand the turning is very predictable.


Damps the vertical movement of the wheels caused by the bumps on the

road

They move one into the

other

Two metal cylinders one

inside the other connected on each end of the pair to

the body by a screw

Suspension

It protects the steering shaft joints from dirt and dust

It contracts and expands

along it’s axleIt’s flexible

Worm like soft plastic tubeShaft cover

Electric engine attached to a lever that moves the drive shaft horizontally

making it turn.

It’s poweredIt moves a

leverIt’s connected to the steering

shaft

Electric dynamo with a metallic

leverSteering engine

Connects the tire to the engine. It also holds all the weight load of the wheel

It’s sturdy and light

It can roll

Metal hoop with built-in spokesRim


The rods, moved by the steering engine, pushes the wheels sideways,

making the turn.

They travel on their

horizontal axle

Three cylindrical metal rods united

to one anotherSteering shaft

Holds the rim in it’s place connecting it to the main chassis.

It can turnIt’s removableIt’s for holding two pieces in

place

Round cilinderwith a marking in

it’s top centerConnection screw



It has grip


tube

Tire

12. Appendix


Rear lights

Chair chassis

Structure

Rear reflectors

Plastic case

Metal skeleton

Electric connectors

Batteries

Front lights

Rear transport attachment

12. Appendix

The structure is completely different too. Without the need to fold down to ease transport and to leave storage room for the batteries, the structure goes from the all seen metal tube structure to the metal frame completely covered by a plastic case. This way it can protect the wires, connections and electrical system from the weather and hold the front and rear lights. This structure looks heavier but also more robust and powerful.


Metal piece to hitch a small trailer or any other thing. It can be used to pull the

wheelchair in case of breakdown or to be pulled by it

It can be grabbedYou can hold

stuff to it

Metallic piece in U shape united to the

metal skeletonRear transport attachment

Electric source for the engine and control system

They’re heavyThey can be

removedThey hold

something inside

Rectangular pieces of black plastic

Batteries

Aesthetic pieces that hides and protects the metal skeleton and the internal parts as

well as housing the front and rear lights

It’s softIt’s not tough

It’s lightweight

Sheet of plastic bent making

organic curves Plastic case

Basic structure where most of the elements connects or to.

It’s sturdyIt can house

something within

Sheets of metal bent and screwed

togetherMetal skeleton

Allows to plug / unplug the batteries to the electric system or to the battery charger

It transports electricityIt can be

connected to another piece

similar to it but with it’s opposite

layout.

Rectangular piece of plastic with

cables entering on one side and a hole in the other with a

metallic sheet inside

Electric connectors

They reflect lightThey shine

They’re fixed

Two circular and a rectangular piece of translucent-textured

red plastic

Rear reflectors


Lights that are used to give away the position of the wheelchair as well as

indicate the direction it’s going to turn.

It’s fixedIt’s lighted from

withinThey’re used for a color language

Four circular translucent-textured disk. Two are white and the other two

are yellow

Front lights

It’s used to pivot the whole chair and allow access to the internal parts for

maintenance

It’s sturdyIt can pivot

Two metal square tubes united to the metal skeleton by a

pair of hinges

Chair chassis

Lights that are used to give away the position of the wheelchair as well as

indicate the direction it’s going to turn.

It’s fixedIt’s lighted from

withinThey’re used for a color language

Two circular translucent-textured

disk in two tone colors

Rear lights

12. Appendix


The main functions of the wheelchair is quite easy to see:

• To move around

• To hold the user

Although this is obvious not all the parts of the wheelchair are made to fulfill this, each one has some role to perform. This study looks in detail at what each single piece of the wheelchair does for the overall chair and find if there is any piece that is being underused and his function can be adapted by another one, or if two pieces realize the same goal see if they can be made into one.

On the following tables the secondary functions are displayed. This are all the other functions that don’t relate directly to the main function but are needed in order to achieve a good product. Some of the functions are repeated on two different pieces of the table, this can be redundant or because they complement each other just as a bolt complement the screw and both are used to hold two pieces together.

As a result of the analysis only the seat, armrest and footrest realize the work of holding the user on the wheelchair while the wheels and the brake are the ones that makes it move around. The structure has the main purpose to hold all pieces together and be strong enough to do not brake apart. The rear wheels on the standard wheelchair are very different from the ones in the front (doesn’t happen so on the electric one) this is due to the need of the outer ring that allows to power the bike and the use of commercial parts from the bicycle market. Both models have a brake that allows them to stay still (not move). It may seem strange that the brake is helping to the function of moving around but the ultimate goal of moving aroud is getting somewhere and once you are there STAY there so you don’t leave the place you wanted to go. So, in a sense, no movement is a sort moving around.

12. Appendix

12. VI Functional analysis of wheelchairs



•Tension the rim•Hold the axle

Spoke

•Hold the air chamber•Hold one side of the spokes•Keep the tire•Keep the wheel round

Rim

•To turn•Attach to the structure•Withstand bumps

Axle

•Move solidarity with the rim•To be hold

Outer ring

•Hold the air chamber•Contact the surface•Give traction•Damper bumps

Tires

Back wheels

•Deform tire•Apply pressure

Brake pad

•Transmit movement•Position the brake

Swing arm

•Grab•Push / pull

Handle

Brake

•Protection•Avoid traspasing

Hand protector

•Rest the forearm•Comfort

Cushion

Armrest

•comfortSoft cushionSeat

•Lean•Hold back•Comfort

Soft back


Assistant handle

Back

FUNCTIONWHEELCHAIR PARTS

SECONDARY FUNCTIONS

12. Appendix


•Hold the foot•Prevent feet sliding•Tough•Light•Able to rotate

Foot plate

•To be light•To be soft•Hold back the legs

Leg strap

Footrests

•Strengthen the skeleton•Allow folding•Guide the folding movement

Folding axis

•Strong•Small•Allow attachment•Allow quick attach/detach

Footrest holder

•Hold all the parts together•Withstand weight•Protection against weather•show color

Skeleton

Structure

•Contact the surface•Give traction•Maintain roundness

Wheel

•Hold the wheel•Allow to turn•Hold weight•Attach to wheelchair

Caster fork

Front wheels


SECONDARY FUNCTIONS

12. Appendix



•Stop the wheelchairMagnetic brake

Rear transport attachment

•Transmit movementSwing arm


Handle

Safety brake

•Supply energy•Weight load

Batteries

•Connect batteries to engine or to chargerElectric connectors

•Provide structural integrity•Hold internal parts•Allow attach of all the parts

Metal skeleton

•Aesthetics•Protect internal parts•Easy to clean

Plastic case

•Hold the chair•Rotate chair

Chair chassis

•Give the position awayRear reflectors

•Give position away•Illuminate the path•Use energy

Front lights

•Give position away•Use energy

Rear lights

Structure

•comfortSoft cushionSeat


SECONDARY FUNCTIONS

12. Appendix


•Hold the foot•Prevent feet sliding•Tough•Light•Able to rotate•Comfort

Foot plate

•To be light•To be soft•Hold back the legs•Comfort

Leg strap

footrest

•Connect the Rim to the wheelchairConnection screw

•Use energy•Rotate the wheel

Engine

•Keep the tire•Keep the wheel round

Rim

•Contact the surface•Give traction•Damper bumps

Tire

Front wheels

•Transform the direction engine movement.•Move the wheels sideway•Move both wheels in the same manner

Drive shaft

•Protect shaft•Able to deform

Shaft cover

•Move the drive shaft•Use energy

Direction engine

•Damper bumpsSuspension

•Contact the surface•Give traction•Maintain roundness•Damper bumps

Wheel

Back wheels


SECONDARY FUNCTIONS

12. Appendix


•Rest the forearm•Comfort

Cushion

•Use energy•Control all the electric systems

Electric controls

armrests

•Grab the know•Turn the knob•Adjust lower back arch

Lordosis adjustment

Back

•Lean•Hold back•Comfort

Cushion

•Grab the lever•Pull/push the lever•Change angle between seat and back.

Recline angle adjustment

•Hold the cushion on place•Rotate the armrest•Guide the electric cables

Structure


SECONDARY FUNCTIONS

12. Appendix


12. Appendix

The use analysis is a list where all the different uses the wheelchair has during it’s lifetime are displayed.

• Manufacturing (standard wheelchair only)– Bending tubes– Welding structure– Bolt down parts

• Transportation of the product from the factory to the warehouse• Election of the product

– At the store• Transportation of the product from the store to the house

– By the user or by a store’s van.• Use of the product

– Sit down– Stand up– Move

• (electric) Moving the joystick from the control panel• (manual) Propelling with the outer ring

– Use the stationary brake– Raise / lower footplate– (standard) fold wheelchair

• Maintenance – Standard wheelchair only

• Water clean the structure• Wash seat cushions• Inflate wheel pressure

– Electric wheelchair only• Take off batteries• Charge batteries• Change bulbs• Hand wash cushions

• Disposal

12. VII Use analysis of wheelchairs


In this section we will study the anthropometric measures that are relevant to the design of a wheelchair. We will make two different charts, one for women and another one for men. We will display the 5, 50 and 95 percentile for both.

This information has been extracted from the book “Problemática de losusuarios de sillas de ruedas en España” (Reference 1), and can be found on pages 79 and 80.

12. Appendix

U1: Arm length U2: Height from the floor to the head

U3: Height from the floor to the shoulder U4: Height from the floor to the elbow

U5: Poplitea height U6: Distance between the buttock and the poplitea hollow

U7: Shoulders width U8: Hips width

U9: Knee angle U10: Distance between the trochanter and the armpit

12. VIII Ergonomics


12. Appendix

90.068.845.0Average weight (kg)

187.0170.0146.0Average size (cm)

47.038.025.0Distance between the trochanter and the armpit (cm)U10

907856Knee angle (º)U9

45.037.027.5Hips width (cm)U8

52.042.333.5Shoulders width (cm)U7

55.046.438.0Distance between the buttock and the poplitea hollow (cm)U6

52.044.735.0Poplitea height (cm)U5

80.772.065.0Height from the floor to the elbow (cm)U4

112.5103.492.6Height from the floor to the shoulder (cm)U3

139.0128.0115.0Height from the floor to the head (cm)U2

75.065.348.5Arm length (cm)U1

p-95p-50p-5Male’s percentile

80.055.531.0Average weight (kg)

170.0156.0130.0Average size (cm)

43.033.021.0Distance between the trochanter and the armpit (cm)U10

907552Knee angle (º)U9

45.037.027.3Hips width (cm)U8

50.037.531.0Shoulders width (cm)U7

54.044.037.0Distance between the buttock and the poplitea hollow (cm)U6

46.039.633.0Poplitea height (cm)U5

79.073.065.0Height from the floor to the elbow (cm)U4

106.098.087.0Height from the floor to the shoulder (cm)U3

131.0122.0107.0Height from the floor to the head (cm)U2

66.058.039.5Arm length (cm)U1

p-95p-50p-5Female’s percentile


12. Appendix

All wheelchairs come with basic parts (like seat back and armrests) due to the particular needs of the different illnesses that needs special add-ons for them. Here is a list of the most common ones. The following table displays the percentage of manual and electric wheelchairs that had the add-on installed.

198Other

2-Side head rest

12Leg support divider

22Tray

51Side support for the chest

43Back support

63Back addon

92Head rest

84Feet holder

39Spoke protector

144Chest belt

146Back cushion

205Seat belt

1920Side clothing protector

2614Heel rest

7156Seat cushion

ElectricManual

This information has been extracted from the book “Problemática de los usuarios de sillasde ruedas en España” (Reference 1), and can be found on page 92.

We can see that many users find the seat uncomfortable, having the 56% of manual wheelchairs and 71% of electric wheelchairs studied an extra cushion.


12. Appendix










This information has been extracted from the book “Problemática de losusuarios de sillas de ruedas en España” (Reference 1), and can be found on pages 96 to 99.

12. IX Technical data



12. Appendix


56.042.035.5Distance between both axes (cm)S16



95.090.082.0assistant’s handle height (cm)S13



90.085.075.0Back height (cm)S10




17.75.4-1.6Seat angle (º)S6

57.550.444.0Height from the front tip of the seat to the floor (cm)S5



114.0

105.079.7Full length (cm)S2


p-95p-50p-5


12. Appendix











S17: Horizontal Length between the seat’s back and the controller

S18: Height between control and the seat


12. Appendix

60.047.044.0Distance between both axes (cm)S16

56.643.031.0Horizontal Length between the back and the controller (cm)S17


35.527.016.0Height between control and the seat (cm)S18



100.093.083.1assistant’s handle height (cm)S13



106.089.072.0Back height (cm)S10




17.56.2-0.7Seat angle (º)S6

60.054.048.0Height from the front tip of the seat to the floor (cm)S5



118.5106.077.0Full length (cm)S2


p-95p-50p-5


To supplement the previous information I’d like to give some information on performance from electric wheelchairs.

The following table is part of the technical data of the Smart model and is available at: http://www.meyra.de/meyraweb/o_basis.pl

-3 –+ 22ºSeat tilt adjust mechanical

0 –+ 22ºSeat tilt adjust electrical

IndirectType of steering

15%Permitted / transverse slope

12%Inclination ability duration

15%Permitted inclination

Approx. 40kmMax. driving range

2x 300 / 200 (10 / 6 km/h)Motor performance W

6/10Driving speeds in km/h

Performance

10Max. Additional loading

140Permitted overall weight

130User weight max.

82Empty transport weight min.

Weights in kg

12. Appendix


ISO charts.

12. Appendix

Static Stability ISO/CD 7176-1

na15.0ºLateral

na11.7ºRear (Uphill) Wheels unlocked

na5.8ºRear (Uphill) Wheels locked

na24.4ºForward (Downhill)

Least StableMost StableStability Direction

Determination of overall dimensions, Mass, and Turning Space ISO 7176-5

18.4kgTotal Mass

.288 cubic metersVolume

No quick release components

Laregest component Dimensions:

810mmRear (Uphill) Wheels unlocked

320mmRear (Uphill) Wheels locked

630mmForward (Downhill)

1015mmStability Direction

ISO 01 (Static Stability) - ISO/CD 7176-1:1995-05-03 (E)ISO 05 (Overall Dimensions) - ISO 7176-5:1986-03-01ISO 07 (Seating Dimensions) - ISO 7176-7:Draft 1992-12-10ISO 08 (Static, Impact, Fatigue) - ISO 7176-8:Draft 1996-05-09

Requirements for Static, Impact, and Fatigue Strengths ISO 7176

Static Strength

Pass1760N Up on Push Handles

Pass440N Upward Force on Footrest

na1000N Downward Force on Tipping Lever

Pass1000N Downward Force on Footrest

Fail1000N Outward Pull on Handgrips

Pass760N Downward Force on Armrest

Pass/FailStatic Strength Test

This are the laws and regulations any given wheelchair has to pass with their most interesting requirements displayed.


12. Appendix

Seating and Wheel Dimensions ISO 7176-7

110mmVertical Location of Wheel Axle

0Horizontal Location of Wheel Axle

610mmPropelling Wheel Diameter

450mmHand Rim Diameter

370mmFront Location of Armrests

390mmDistance Between Armrests

400mmArmrest Angle (Radius)

20mmArmrest Width

490mmArmrest Length

370mmFront of Armrest to Backrest

250mmArmrest Height

93.8ºLeg to Seat Surface Angle

21.0ºFootrest Angle

120mmFootrest Length

75mmFootrest Clearance

420mmSeat to Footrest Height

360mmBackrest Width

380mmBackrest Height

17.9ºBackrest Angle

460mmSeat Surface Height

390mmEffective Seta Width

400mmMaximum Seat Width

470mmEffective Seat Depth

17.5ºSeat Plane Angle

Impact Strength

PassFootrest Longitudinal Impact

PassFootrest Lateral Impact

PassCastor Impact

PassHandrim Impact

PassBackrest Impact

Pass/FailImpact Strength Test

Fatigue Strength

6666Two - Drop Test

200,000Two - Drum Test

Cycles CompletedFatigue Test


12. Appendix

The urban outdoors are basically composed of paved roads with sidewalks, traffic, ramps and stairs and parks where vegetation, slopes and uneven terrain can be found.

On the paved roads the firm ground will allow an smooth ride along the sidewalk. With standard wheelchairs the user has to be careful with small debris that may encounter as they can lock the small front wheels, falling both the chair and the user to the ground. Crossing the street will force the wheelchair user to change sidewalks. Many sidewalks have ramps to ease the transition between them, although they may be blocked or need of a detour to get to cross. If there are no ramps, the wheelchair user will have to overcome the step created by the sidewalk as he goes down and up from one side to the other. Depending on the height of that step a wheelchair may or may not be able to cross without dumping the passenger. Even if the sidewalk is low enough to allow the crossing the maneuver is slow and requires an amount of time that is not been taken into consideration when programming the traffic lights.

Traffic is another concern when going down the street. Heavy traffic will unable the handicap person on the wheelchair to see where he is going as he is placed on a lower position than the rest of the pedestrians. It will also impede other people to see the wheelchair coming and can get in the way.

When willing to get into a building, sometimes there is a last barrier: a single step or a small stair between the sidewalk and the door level. In many big public buildings the entrance is leveled with the street or has a ramp for wheelchairs. If there is a step a wheelchair can try to overcome the obstacle being a bit complicated to hold the door open as trying to approach the entrance in a way to get up the step. In case of a short stair then there is some differentiation between electrical and standard wheelchairs. Due to the weight and configuration, electric wheelchairs wont be able to climb up the stairs and standard ones will only be able to do so backwards, making difficult to open the door by themselves.

12. X Environment requirements


12. Appendix

When going to a park has some differences from paved roads. First the path in witch to move may be flat, but it also may have some organic formations such as gentle slopes. It can be paved but also can be compressed earth. This soft terrain the wheels (specially the thin ones from the standard wheelchair) can be bogged down as they dig into the soil. The same can be applied with vegetation (flowers, tree roots, etc). If there is some slope on the transverse flow of the path, the handicap person will have to be cautious as the wheelchair can flip and fall to the ground.

Once indoors the problems are different. While on the outdoors there are big spaces to maneuver and the floor is somewhat flat , indoors have smooth flat surfaces and tight room to move around. The electric scooter wheelchairs are not able to move efficiently in this environment and sometimes not able to move at all needing a standard-like wheelchair (being it standard, lightweight or electrical). At the wheelchair owner’s house the corridors become to narrow to move comfortably as there is barely enough room to get the hands on the outer ring to propel. The rooms are filled with furniture becoming obstacles to move around them. The most critical example is the bathroom where the normal apartments try to save space and cram all making it impossible to get in with a wheelchair. It is clear then that the layout of many apartments are just not thought for wheelchair use. But it is not only the layout but the type of furniture used. The person on a wheelchair lives on a sitting position, making impossible for him to reach any object from closets that will be easy to access from a standing position.

Another indoor situation given is when the wheelchair user is entering a public building, be it an office or government building or a store. This usually have more space to maneuver, the corridors are wider and are less furniture on it. On the other hand it has more human traffic making it difficult to move freely.


12. Appendix

The wheelchair is what the handicap person will use to move around with. But at some point he will have to move away from it for different reasons:

• To go to the toilet (fig 4.4.2)• Take a shower • Go to bed (fig 4.4.1, 4.4.4 and 4.4.5)• Changing to a normal chair• Laying in a couch• Putting a pillow on the wheelchair

This activities demand special attention as the handicap person needs to do an important amount of force in order to move his body from one place to the other. Depending on the illness he suffers he may need a third person to help him or move him.

(fig 4.4.2)(fig 4.4.1) (fig 4.4.3)

(fig 4.4.4) (fig 4.4.5)

This information has been extracted from the book “Manual del usuario de sillade ruedas” (Reference 2), and can be found on pages 47 to 50.

12. XI Body transfers

design of an urban wheelchair

Documents