i

Group 13: Highly Adjustable Power Wheelchair Back

Support April 30, 2015

Jiahui

Liu

Zhengdi

Wang

Nick

Hohman

John

Buddenberg

Alexander

Weber

Christopher

Wasco

ii

Abstract

There are roughly 12,000 new cases of spinal cord injury every year with 200,000 cases

in the United States. Spinal cord injuries have varying consequences depending on the location

of the injury as a spinal cord injury generally results in a break in connection of the central

nervous system to the nervous tissue past the site of injury. Some impairment can be tetraplegia

with no arm control as well as vary to paraplegia with full trunk and arm control. Assistive

devices for tetraplegia with some arm control are most often power wheelchairs as these

individuals can utilize a joystick for steering. The power wheelchair’s back is pertinent for

holding an individual’s trunk in correct anatomical position and maximizing their range of

motion. Today, there are two schools of thought for current power wheelchair backs: expensive

and highly customizable or cheap and rigid. The expensive wheelchair backs, though they are

highly customizable, are very difficult and time consuming to adjust. Even cheaper models must

be completely interchanged utilizing supplied tools. The goal of this project was to create a

design that has the ability to fit various body types, such as a customizable wheelchair back, but

will be easier and less time consuming to adjust. Our device will be aggressively priced, but will

still offer the high customizability found in more expensive models. Also, our device will be

able adjust without the need for tools nearly instantly and the time for fitting a new wheelchair

will be reduced compared to current practices. This device will retain the current high standard

for proper back support so that an individual does not feel limited independence when the newly

created back is installed.

iii

Acknowledgements

We would like to acknowledge our mentors, Sandra Metzler and Carmen DiGiovine as

well as the clinicians in the wheelchair fitting room who helped us come up with our idea and

better our understanding of what makes a good wheelchair back. We would also like to thank Joe

Stidham from Quantum Rehab for providing the group a wheelchair that was used in the design

and testing of our device. In addition we gratefully acknowledge the financial support provided

by a National Institutes of Health (NICHD R25) grant.

iv

Table Of Contents

Group 13: Highly Adjustable Power Wheelchair Back Support.............................................. i

Abstract .................................................................................................................................................... ii

Acknowledgements ............................................................................................................................. iii

Table Of Contents ................................................................................................................................. iv

Table of Figures .................................................................................................................................... vi

Table of Tables .................................................................................................................................... viii

Introduction ............................................................................................................................................ 1

Chapter 1: Background ....................................................................................................................... 4

Clinical Background ......................................................................................................................................... 4

Sitting Anatomy .............................................................................................................................................................. 5

Current Assistive Device Background ....................................................................................................... 8

The New Assistive Device ............................................................................................................................ 10

Chapter 2: Requirements ................................................................................................................. 12

Functional Requirements ............................................................................................................................ 12

Non-Functional Requirements .................................................................................................................. 13

Look and Feel Requirements .................................................................................................................................. 13

Performance and Usability Requirements ........................................................................................................ 14

Legal Requirements .................................................................................................................................................... 15

Cost Targets .................................................................................................................................................................... 15

Sustainability ................................................................................................................................................... 16

Standards .......................................................................................................................................................... 16

Stakeholders/Users ....................................................................................................................................... 17

Chapter 3: Concept Selection .......................................................................................................... 19

Development of Initial Concepts............................................................................................................... 19

Concept Screening .......................................................................................................................................... 23

Conceptual Design ......................................................................................................................................... 24

One piece air bag back support .............................................................................................................................. 24

Three pieces back support ....................................................................................................................................... 25

One piece attachable back support ....................................................................................................................... 26

Multiple pieces back support .................................................................................................................................. 27

Selection Process ............................................................................................................................................ 28

Description of Final Proposed Design .................................................................................................... 33

Chapter 4: Testing ............................................................................................................................... 38

Testing and Evaluation Plans ..................................................................................................................... 38

Device Evaluation and Analysis ................................................................................................................ 44

Clinical Evaluations ..................................................................................................................................................... 44

v

Engineering/Static Tests .......................................................................................................................................... 45

Dimensions Testing ..................................................................................................................................................... 49

Ignitability Testing ...................................................................................................................................................... 52

Chapter 5: Conclusion ........................................................................................................................ 56

Summary ........................................................................................................................................................... 56

Improvements ................................................................................................................................................. 57

Conclusion ........................................................................................................................................................ 60

References ............................................................................................................................................. 61

Appendix A: Selected Sketches ....................................................................................................... 63

Appendix B: Morph Charts ............................................................................................................... 77

Appendix C: Large Concept Map ..................................................................................................... 78

Appendix D: Assembly Instruction Manual ............................................................................... 79

Appendix E: Instructions for Patients and Clinicians ............................................................ 82

Appendix F: Dimensioned Engineering draft drawings ....................................................... 84

Appendix G: Bill of Materials ........................................................................................................... 96

Appendix H: Final Budget ................................................................................................................. 97

Appendix I: Actual Timeline of Build (Final 3 Months) ......................................................... 98

vi

Table of Figures

Figure 1: Image of 5 sections of spinal cord .................................................................................................................... 2 Figure 2: Lordotic (more natural) spine positioning vs. pelvis posterior tilt spine positioning ................. 6 Figure 3: Standing vs. sitting position of spine ............................................................................................................... 6 Figure 4: Matrix Back [4]. ....................................................................................................................................................... 8 Figure 5: Sliding Plate Patent [5]. ........................................................................................................................................ 9 Figure 6: The reclining seat back [7]. .............................................................................................................................. 10 Figure 7: Concept map generated through organization of main components of initial concept

sketches. ........................................................................................................................................................................... 19 Figure 8: Graphic representation of one of the concept sketches ........................................................................ 20 Figure 9: Graphic representation of one of the concept sketches ........................................................................ 21 Figure 10: Graphic representation of one of the concept sketches ..................................................................... 22 Figure 11: One-piece air bag back support ................................................................................................................... 25 Figure 12: 3 pieces back support ...................................................................................................................................... 26 Figure 13: One-piece attachable back support ............................................................................................................ 27 Figure 14: Multiple pieces back support ....................................................................................................................... 28 Figure 15: Final Screening Design .................................................................................................................................... 34 Figure 16: A set of sketches showing a potential final design ............................................................................... 35 Figure 17: A figure showing the details of the pads and telescoping ball and socket joints ...................... 36 Figure 18: Front view of the Solidworks design mock-up ....................................................................................... 36 Figure 19: A side and isometric view of the Solidworks design mock-up ......................................................... 37 Figure 20: Sample survey to be completed by a therapist after they have tested/used the device. ....... 41 Figure 21: Sample survey to be completed by a user after they have tested/used the device. ................ 42 Figure 22: Stability tested Device ..................................................................................................................................... 46 Figure 23: Result of pressure mapping .......................................................................................................................... 48 Figure 24: Depicting overall width of the wheelchair when fully extended..................................................... 50 Figure 25: Depicting overall height of the wheelchair when fully extended ................................................... 51 Figure 26: Depicting overall length of the wheelchair when fully extended ................................................... 52 Figure 27: Sizes of foam specimens from ISO 7176-16............................................................................................. 53 Figure 28: Vertical section through test rig assembly for foam specimens from ISO 7176-16 ................. 53 Figure 29: Initial burning of the cigarette end ............................................................................................................ 54 Figure 30: Result of continued smolder of foam and cover .................................................................................... 54 Figure 31: Result of the cigarette testing on the foam .............................................................................................. 55 Figure 32: Final Design of Device ..................................................................................................................................... 57 Figure 33: Initial concept designs obtained from each group member. (Click on object to open up .pdf

file of full concepts) ...................................................................................................................................................... 63 Figure 34: Initial concept designs obtained from each group member. (Click on object to open up .pdf

file of full concepts) ...................................................................................................................................................... 64 Figure 35: Initial concept designs obtained from each group member. (Click on object to open up .pdf

file of full concepts) ...................................................................................................................................................... 65 Figure 36: Initial concept designs obtained from each group member. (Click on object to open up .pdf

file of full concepts) ...................................................................................................................................................... 66 Figure 37: Initial concept designs obtained from each group member. (Click on object to open up .pdf

file of full concepts) ...................................................................................................................................................... 67 Figure 38: Initial concept designs obtained from each group member ............................................................. 68 Figure 39: Initial concept designs obtained from each group member ............................................................. 69

vii

Figure 40: Initial concept designs obtained from each group member ............................................................. 70 Figure 41: Initial concept designs obtained from each group member ............................................................. 71 Figure 42: Initial concept designs obtained from each group member ............................................................. 72 Figure 43: Initial concept designs obtained from each group member ............................................................. 73 Figure 44: Initial concept designs obtained from each group member ............................................................. 74 Figure 45: Initial concept designs obtained from each group member ............................................................. 75 Figure 46: Initial concept designs obtained from each group member ............................................................. 76 Figure 47: Large Concept Map ........................................................................................................................................... 78 Figure 48: The Mid side bolsters. There are two of these, one is simple upside down on the opposite

side. .................................................................................................................................................................................... 84 Figure 49: The ball of the ball and socket joints with telescoping rods ............................................................. 85 Figure 50: The stainless steel backplate ........................................................................................................................ 86 Figure 51: The lower side pieces. As with the mid side, there are 2 of the same just mirrored on the

other side ......................................................................................................................................................................... 87 Figure 52: The mid-mid support piece ........................................................................................................................... 88 Figure 53: The lower mid support piece ........................................................................................................................ 89 Figure 54: The L-bar that connects the stainless steel back to the wheelchair ............................................... 90 Figure 55: The shoulder supports. As with the mid-sides and lower sides, there is two copies of the

one version, just upside-down ................................................................................................................................. 91 Figure 56: Final Solidworks rendering - side ............................................................................................................... 92 Figure 57: Final Solidworks rendering - front ............................................................................................................. 93 Figure 58: Final Solidworks rendering - iso ................................................................................................................. 94 Figure 59: Final Solidworks rendering - top ................................................................................................................ 95 Figure 60: Final Timeline Gantt Chart ............................................................................................................................ 99

viii

Table of Tables

Table 1: Ranking each criteria to obtain weight values. .......................................................................................... 30 Table 2: Design matrix used to compare the four design concepts. .................................................................... 31 Table 3: Results for the stability test under various moving speeds .................................................................. 46 Table 4: Results for the stability test under various directions ............................................................................ 47 Table 5: Results for fatigue test for each piece ............................................................................................................ 48 Table 6: Morph chart for Adjustability ........................................................................................................................... 77 Table 7: Morph chart back piece ...................................................................................................................................... 77 Table 8: Morph Chart for Base attachment ................................................................................................................... 77 Table 9: Morph Chart for Support .................................................................................................................................... 77 Table 10: Bill of Materials ................................................................................................................................................... 96 Table 11: Timeline Items ..................................................................................................................................................... 98

1

Introduction

The power wheelchair is a great tool for people with a variety of different impairments

and conditions. It is able to improve the independence of the user and allow them to ambulate

much more freely. An important aspect of the power wheelchair is the back support. The back

of a wheelchair is critical in providing support and comfort to the user. There are many

conditions that result in an individual needing to use a power wheelchair, but this report will

focus on individuals with spinal cord injuries. With these individuals, support and stability can

be very important, so the need for a wheelchair back support to provide this support and stability

is critical.

The spinal cord is divided into 5 sections and consists of 33 total vertebrae. The 5

sections of the spine are the cervical spine, thoracic spine, lumbar spine, sacral spine, and coccyx

and within the spinal column extend the spinal cord itself, which runs from the base of the brain

down the back to the waist. The five sections of the spine can be seen in Figure 1. There are

about 12,000 spinal cord injuries that occur every year and where the injury occurs on the spine

determines the resulting impairments for the individual. Individuals who suffer from thoracic

and cervical spine injuries will have impairment of the trunk and core muscles, which will result

in impaired postural control [1]. Postural control

2

is simply the ability to remain in an upright and balanced position in a seated posture.

This project will focus more on individuals with a cervical spinal cord injury because those with

a thoracic spine injury still have good function in the arms and may be able to utilize a manual

wheelchair.

Figure 1: Image of 5 sections of spinal cord

The purpose of this project is to design a new power wheelchair back support with a

focus on advancing the adjustability and customizability to suit many different individuals with

relative ease and quickness. This new style of wheelchair back will not only provide the comfort

desired in power wheelchairs, it will allow the physical therapist to make fine adjustments at a

quick pace for properly supporting individuals. This is opposed to the current standard of having

to use different tools for adjustment and even have the individual move in and out of the chair for

each adjustment made to suit them. Along with being more adjustable and permitting a more-

custom feel for each individual, the new device proposed will be aggressively priced to compete

3

with current “cheap” wheelchair back models so that each individual who needs a power

wheelchair may have the experience of a high end, custom built back.

4

Chapter 1: Background

Clinical Background

The spinal cord is a large bundling of nervous system tissue that goes from the base of

the brain along the vertebral column. Neurons that extend to the rest of the body and either

control glands and muscles or sense an individual’s surroundings all collect somewhere along the

spinal cord. One injury to cause impairment to the spinal cord that may limit an individual’s

independence is simply named: a spinal cord injury. A spinal cord injury is most basically when

there is a break or dislocation of the bones around the spinal cord, an object goes through or

between the bones (such as a bullet or knife), or there are damages to the disks between the

bones and pushes them against the spinal cord. The spinal cord can also be damaged by different

infections or tumors growing into the spinal cord area. The misconnection of the brain to the

extremities after the injury in the spinal cord behaves much like a break in an electrical wire will

not allow electrical signals to propagate down the wire that is past the broken section. These

spinal cord injuries may end up resulting in a paralysis in which the degree of paralysis is

dependent on the location of the spinal cord injury.

Each year, there are roughly 12,000 new spinal cord injuries with 200,000 individuals

with spinal cord injuries in the United States [2]. Different injury levels along the spinal cord

determine the level of injury for each individual. For example, an injury at the C1-C8 vertebrae

may result in tetraplegia with no trunk control whereas an injury below the T8 vertebrae may

result in paraplegia with complete trunk control. A manual or power wheelchair, in cases where

5

impairments may not allow use of a manual wheelchair, may help to increase an individual’s

independence.

Sitting Anatomy

The anatomy involved in sitting is an important aspect to consider when talking about

power wheelchairs. A comfortable, supportive backrest is very important in maintaining a good

quality of life in a power wheelchair user. When an individual sits down, the body does not

automatically adjust to achieve optimal spinal and pelvic alignment [3]. This means that it is

relatively easy to get yourself in a bad, potentially harmful position when sitting. This is

especially important for power wheelchair users, who will be in a seated position for the majority

of their life.

It is important to note that in general, the position of the pelvis determines the shape of

the spine. This is due to the rigid connection between the sacrum (bottom of the spine) and the

pelvis. As a result, when going from a standing to a seated position, the pelvis will tend to rotate

backwards. This posterior tilt of the pelvis causes the lumbar spine to shift out of its natural,

preferred, lordotic curved position and assume a more flattened, straight line shape, as seen in

Figure 2 and Figure 3, below [3]. This backwards rotation of the pelvis means that the lower

back is not supported properly, which can lead to pain, discomfort, and additional pressure on the

abdomen, spinal cord, nerve roots, and intervertebral discs [2].

6

Figure 2: Lordotic (more natural) spine positioning vs. pelvis posterior tilt spine positioning

Figure 3: Standing vs. sitting position of spine

The potential impact of these problems means that it is very important for the backrest of

a power wheelchair to provide support and stabilize the pelvis. It can do this by helping to

prevent the posterior tilt and ensuring a more natural curve of the spine. Looking at the anatomy

of the seated position shows how important lumbar support can be in a backrest. Because the

power wheelchair user will be seated in the wheelchair for extended periods of time, comfort is

an important issue. If the backrest does not provide the correct lower back support, the user may

start to experience some of the problems mentioned above such as pain, discomfort, and added

pressure on the spine. This will drastically reduce their quality of life, and may even affect other

things such as appetite. These are unwanted complications that can be prevented or minimized

with a quality backrest. The fact that spinal cord injuries often involve impairment of the trunk

and core muscles (resulting in impaired postural control) means that power wheelchair back rests

7

must provide good trunk and core support, as well as lateral support to help make sure the

wheelchair user remains upright and balanced in their seated posture. Maintaining good posture

is important to help prevent pressure points from forming in the spine. Good posture is also

important when considering range of motion. A person that is seated in a slumped position will

have a lower range of motion than an individual sitting in a more upright and anatomically

correct position. This slumped position will also decrease a person’s quality of life and make

everyday tasks such as brushing your teeth, eating, or drinking more difficult.

This project will focus mainly on power wheelchairs for individuals whose injuries occur

at the C5-C7 vertebrae level as this may result in a type of tetraplegia that allows some limited

upper limb control (moving a joystick, limited range of motion, etc.). Injuries to the C5 to C7

vertebrae have specific requirements for a power wheelchair back. This includes some posture

maintenance as the individual may have decreased trunk control. The proper wheelchair back

will hold the individual’s spine in the correct anatomical position where the pelvis has an

anterior tilt so that there is less stress on the spine and internal organs. Another benefit of

supporting the anterior pelvic tilt allows the individual to maximize the arms’ range of motion so

that independence is further increased with the added mobility of the power wheelchair. This is

what makes the back of a powered wheelchair a pertinent part to the whole wheelchair;

independence of an individual with impairment is maximized and brought back as close to

normal as possible. We would like to minimize the restrictive aspects of today’s wheelchairs

while maximizing the anatomical and biomechanical advantageous support functions with our

new wheelchair back design.

8

Current Assistive Device Background

Currently, devices that are highly customizable are expensive such as the MATRIX back

(see Figure 4) at over $4,000 for a child’s size seat and adjustments generally require specific

tools like Allen wrenches and screwdrivers and can be a time consuming process. Other, less

expensive models may not be as customizable and suit each individual type with ease. In other

cases, there are many very slightly different versions of the same model wheelchair back, which

requires the physical therapist to remove and reinstall a new back. Eventually, a therapist will fit

a back to each individuals’ needs, which can be a very time consuming, and daunting task.

Figure 4: Matrix Back [4].

9

A couple of currently patented power wheelchair backs include a model where the back

post is a hybrid model backing which includes a support plate with a sliding plate mechanism

attached which allows for basic adjustments between upright and a reclined position as shown in

Figure 5. Another patented back uses a reclining seat with a movable back support. The back

frame is coupled to the padded back support, which allows for the back support to be altered by

manual adjustments to the frame. In addition to this, a user is able to independently change the

back support without changing the back frame. This is depicted in Figure 6.

Figure 5: Sliding Plate Patent [5].

10

Figure 6: The reclining seat back [7].

The New Assistive Device

Generally, this new device needs to properly support individuals’ backs as well as be

adaptable to many different body types. Most specifically, this new wheelchair back for

powered wheelchairs will be most beneficial to the population of individuals who have sustained

a spinal cord injury. These individuals will require attention to proper back support and

alignment as impaired posture control and strength may be a result of the spinal cord injury. It

may be difficult and time consuming to move these individuals each time a small adjustment is

required for proper alignment and the new back for the power wheelchair created will cut down

on this time as well as increase the customizability for each type of individual.

11

As previously mentioned, the new assistive device will be easily and quickly adjustable

while still providing reliable back support including the rib bolstering desired by many physical

therapists to impaired individuals. The new device will also allow the maximum range of motion

so that a higher level of independence can be given to individuals who utilize a power

wheelchair. The new device will be able to accommodate many different body types while still

remaining cost effective. The device will, therefore, need to be stable for body types that are

recommended by the wheelchair base. The wheelchair base the new back is being designed for

is a Pride Mobility Quantum Q6 Edge because that is the model that was selected for us to

use.

The major restrictions on this device will be keeping the cost at a low, competitive price

while still refraining from infringing on currently patented devices. The cost will be a major

restriction as new designs that are highly adjustable generally have many expensive mechanical

components that will increase manufacturing cost. It will also be difficult to find a material that

will be cheap enough to keep cost to own low while still retaining the long-term sustainability

and comfort that is desired for power wheelchairs. Perhaps even more importantly, the back will

need to retain the proper shape for the length of the back as well as hold its custom adjustments

for each individual over the wheelchair back’s lifetime.

Currently, there is no device that allows this highly customizable back that is also

relatively straightforward to adjust and does not require tools or complete disassembly for many

different body types and is reasonably priced for any individual with a power wheelchair to

purchase. The creation of this device will allow physical therapists to efficiently place

individuals into powered wheelchairs while maintaining a comfortable experience for the

individual.

12

Chapter 2: Requirements

Functional Requirements

In order to create a back support that is able to account for the current limitations that are

currently on the market, one must look at the very basic functions that the back support must

accommodate. The new back support will be a new design with the goal to provide the exact

specialized support to an individual that a custom support could provide and have the cost

effective and simplicity of a basic back support. Before initial designing of the back support, the

group thought of functions that the back support, no matter what shape it takes, should be able to

accommodate.

First, the back support should provide stable support to the individual through multiple

contact points along the posterior region of the individual. The back support should provide

support to an individual’s head, below their shoulder blades, near each underarm and near their

iliac crest. The device should be able to provide support to these areas, which in return would

allow the individual to maintain proper support on their spine [7]. These five contact points were

chosen in reference to the book Special Seating: An Illustrated Guide. Analysis of the trunk

chapter the information was used to select these five contact points. This must mean that the

design of the back support should be able to provide contact support to these specific areas of an

individual.

In order to provide support to these five contact points on an individual, the device must

have the ability to support dimensions up to 75 inches and 300 lbs. The back support must be

able to be adjustable to accommodate different body specifications. Upper weight limit of the

back support was chosen based on the maximum weight capacity of the wheelchair that was

assigned to our project. The wheel chair, Quantum Pride Q6 Edge, contains a maximum limit of

13

300 lbs. therefore our back support should have the ability to be used by individuals up to 300

lbs. [8]. This does not mean the back support should support all 300 lbs. of an individual on each

spot of the design; the back support should not fail to provide proper support to individuals of

300 lbs. The support should accommodate individuals up to 75 inches. This value is determined

based on the average height of male individuals in the United States found from the Centers for

Disease Control and Prevention. Males were used as a basis for this decision due to the larger

average height of males compared to women. Based on a population Census for 2007-2008 this

height includes 95.8% of the entire nation of males from ages 20-79. Based on this the device

shall be designed for individuals up to 75 inches to be able to account for the most appropriate

male heights.

Additionally the back support should provide support to the lumbar region of the spine.

There are many products on the market that use lumbar support as one of their marketability

strategies, products not only includes wheelchair back supports but also car seats and office

chairs. Therefore the new power wheelchair back support should also contain lumbar support to

be competitive with the market. The lumbar support should be able to extend at least 2.5 inches.

This value was based on having group members sit with their back parallel to the wall where

they arch their back. The distance between the wall and the farthest point of the back was

measured to obtain the 2.5-inch value.

Non-Functional Requirements

Look and Feel Requirements

If an individual is preparing to purchase a new product, sometimes how the product looks

and feels takes as important of a role as function to the user. Therefore the back support must be

comfortable and aesthetically pleasing in order to accommodate the individual’s interest when

14

using the back support. The back support should minimize or cover sharp edges on the surface

that surface that will be exposed to the individual. The device should provide comfort through

the cushioning of contact point with the individual. Stated above the back support should make

contact with the neck/head, below shoulder blades, near underarms, and near iliac crests for

stability; to provide comfort to these back support, there should be a cushion lining the area

between the back support and the individual. The back support should also not cause the

individual to feel confined. The back support will be able to accommodate individuals up to 75

inches and 300 lbs. When an individual with one of these dimensions is using the back support,

they should not feel enclosed by the product. The product should not encapsulate the individual

causing them to feel contained in the support.

Performance and Usability Requirements

The back support system will be attached to the power wheelchair through the two

vertical posts that are extending upwards from the base of the support. The back support should

be connected securely to these posts so that if the wheelchair undergoes any movement such as

over rough terrain, the movement will not displace the back support from the wheelchair posts.

The back support should be able to operate under various conditions such as change in

inclination.

The back support should not impair proper care of the individual. Often individuals in

wheelchairs will need to be moved from the wheel chair either by a physical therapist or a

caretaker. Individuals can be moved for a variety of different reasons such as to bathe or for

cleaning the chair. The design of the back support shall not impede the ability for the caretaker or

the physical therapist to provide assistance to the individual. The back support should be

15

designed so that physical therapists and caretakers are able to provide the same amount of care

that can be provided when using other products on the market.

Legal Requirements

The functions of the back support must be researched to ensure that our device will not

interfere with current patents. Currently, there are many patents that are present for different

aspects that our wheelchair hopes to provide. Our device will need to be designed not only to not

interfere with power wheelchair back supports but also with normal office chair supports. This is

due to certain patents that are held by office chairs but are able to be incorporated into a power

wheelchair back. An area of office chair patents mainly consists of lumbar support methods.

The device will also want to be designed to prevent legal action against the group that can

be provided through harm to the individual. The product should be designed to reduce possible

liability in harm. After research it is determined that the back support will not need to require a

510(k) submission. The wheelchair back is viewed as an accessory to the wheelchair and

therefore is classified as a class 1 device [9].

Cost Targets

In order to determine cost target for the back support, analysis of current market devices

was completed. The current price points for the current back supports range from $500 to $700.

In order to provide a device that is able to financially compete with the current devices on the

market, our back support has a goal retail-selling price of $500. Our device is on the lower end of

the cost range of current back supports however, when looking at the current devices, products

around $500 are not adjustable and are very basic. Therefore, we believe if our device is

designed to be easier suited to different individuals bodies and appear as more of a custom

16

support while still having the basic support price, it would financially compete with products on

the market.

Sustainability

After researching on warranties and designed lives on existed devices, the expected

design life for this device is approximately 5-10 years. Since the spinal cord injury individual

might use the wheelchair all the day for a long time even rest of their lifetime, the device will be

designed to allow adjustability between different individual spinal shapes. The devices will be

able to be altered in case an individual needs to alter their spinal positioning through the back of

the chair. Therefore the device should be designed to be reusable during its lifetime of the

product. It is better that the new device can fit in Q6 wheelchair, once the wheelchair life ends,

the material of the back support can be recycled, so that the manufacture company can reduce the

production of new wheelchairs and avoid waste.

Standards

When designing the back support of the wheelchair, the paramount safety, health and

welfare of wheelchair must be concerned. Also general principles such as design priorities,

accommodating users’ characteristics and risk of use error need to be considered. In order to

ensure the usability of our wheelchair, the standards for wheelchair in AAMI/ANSI have to be

followed.

The static stability of our wheelchair is determined in ISO 7176-1:1999 Wheelchairs.

This part specifies the test methods for determining the static tipping stability of wheelchairs,

including scooters. ISO 7176-2:2001 Wheelchairs determines the dynamic stability of electric

wheelchairs. This part specifies test methods for determining the dynamic stability of electrically

powered wheelchairs. ISO 7176-5:2008 Wheelchairs will be referenced to determine the

17

dimensions, mass and maneuvering space for the wheelchair. ISO 7176-5:2007 specifies

methods for the determination of wheelchair dimensions and mass. This includes specific

methods for the determination of outside dimensions when the wheelchair is occupied by a

reference occupant and the required maneuvering space needed for wheelchair maneuvers

commonly carried out in daily life. ISO 7176-8:1998 Wheelchairs provides Requirements and

test methods for static, impact and fatigue strengths. The control system for electrically power

wheelchair is defined in ISO 7176-14:2008 Wheelchairs. It sets safety and performance

requirements that apply during normal use and some conditions of abuse and failure.

Determination of static, impact and repetitive load strengths for postural support devices shows

in ISO 16840-3:2006 Wheelchair.

Another biological evaluation of medical devices standards also has to be followed. ISO

10993-1:2009 describes the general principles governing the biological evaluation of medical

devices within a risk management process and the general categorization of devices based on the

nature and duration of their contact with the body. ISO 10993-13:1999, ISO 10993-15:2000 and

ISO 10993-14:2001 are the Identification and quantification of degradation products from

polymeric, metals, alloys and ceramics devices which will provide the standards for the materials

that used to do the wheelchair. Clinical investigation of medical devices for human subject is

required in ISO 14155:2011 [10, 11].

Stakeholders/Users

The primary user is an individual with spinal issues who have unique postural support

needs as well as their family and caregivers. The new assistive device will be highly adjustable

and customizable while it will still be comfortable and durable. The new device will mostly

follow the shape of human body; especially the spinal column and rib contour of the body, so

18

that the wheelchair will provide a more comprehensive back support to each individual. Physical

therapists and occupational therapists, which might use this device as a therapeutic aid or make

recommendations to the individuals, is one other user group. Having a wider perspective, the

medical device and health facilities manufacture or supply company will be affected, since they

will compare the new devices to the existed ones, which have already on the market and choose

the more effective ones.

19

Chapter 3: Concept Selection

Development of Initial Concepts

When beginning initial concept design, each engineering student originally generated

twenty concepts while the physical therapist student generated five concepts all separately. These

sketches were created individually and portrayed differed aspects of the designs. During the

creation of the concepts, group members did not discuss individual designs during this process.

All concepts are located in Appendix A. After initial brainstorming sketches were completed,

and group members discussed concepts. Each member stated what the pros and cons of each

design where a concept chart was created with various design ideas. The concept chart was

created with the help of bubbl.us and can be located in Figure 7. A very large version can be

found in Appendix C.

Figure 7: Concept map generated through organization of main components of initial concept sketches.

The concept map was designed in hierarchal order all leading to the creation of a new

power wheelchair back support. The concept map assisted members in visualizing the concepts

20

by grouping different aspects of each design within the “family” for the design. For example,

when referring to Figure 7, there were two mechanisms that concepts were designed when

determining between mechanical adjustability and electrical adjustability. Group members could

then see that when referring to electrical adjustability, only two concepts were creating in the

sketching process, computer programmed and switch operated.

The concept chart was created off of the design concepts that were created by each

member. Each member created the designs independently from one another but when members

looked at others concept sketches, it was noticed that members tended to focus on different

aspects of the design. For example one member tended to focus on the different concepts that can

be used to create adjustability between the device while another member focused some concepts

on designing to support the head and neck. Many of the concepts varied from each other and

only a handful of the concepts were similar between two different members. Images of all

concepts can be viewed in Appendix A.

Figure 8: Graphic representation of one of the concept sketches

21

One example of the concept sketches can be viewed above in Figure 8. In this concept

the back support would be designed as flat rectangle piece initially when appearing from the

front. On both the right and left side of the support, there would be additional comfort cushion

such as found on office chairs that would be used to keep the individual centered within the

center region of the support, Within this center region the back support would be lined vertically

with air pockets that can be adjusted to provided more or less support to individual areas. These

air pockets would not go to the very bottom of the support. Below the air pockets would be a

slightly decreased cushion area that can be used for an individual to rest the lowest portion of

their back, upper portion of their Gluteus Maximus, into this region to assist in acquiring a

seating position that would allow the spine to rest in a more natural position. The air pockets

would be adjustable through a computer software program that would manually change the air

pressure in each pocket to a clinician desired position. By having the vertical air pockets,

individual shorter would not require all air bags to be used but it would then be able to be

adjusted for individuals larger by filling additional air pockets.

Figure 9: Graphic representation of one of the concept sketches

22

A second example of a concept sketch that group members designed can be viewed in

Figure 9. This design focused on providing different support in various regions along the spine.

In this instance there would be a distance between the piece attaching the support to the

wheelchair and the wheelchair cushion. The two pieces would be attached through springs

spanning the distance. Different positions can use different spring resistances in order to provide

more support in different areas. The cushions would be separated and would be able to move

individually from each other allowing a more custom feel by the individual using the device.

Figure 10: Graphic representation of one of the concept sketches

A third example of a concept sketch can be viewed in Figure 10. This design did not

focus largely on the back support but rather included a piece that could be used to support the

head and neck region of the individual. The back support is designed in a very basic shape and

can be created with mesh pad that would allow breathability for the individual. The back support

has an attachable head support that is connected through several (>4) very adjustable pieces that

allows the head support to be moved forward/backward and up/down. By creating the attachment

piece through several small pieces it increases adjustability that the neck and head support is able

to provide. The neck and head is designed to follow the curve vertical aspect of the neck

23

immediately below the skull and will curve when it reaches the base of the skull. This design

would provide a very minimalistic support while maximizing the desired support areas.

Concept Screening

The team came up more than 100 design concepts at first so a concept screening process

was necessary to narrow down the ideas. To be objective, the teams did go/no-go evaluation

based on the possibility to build, ease of use, safe for individual/PT, adjustability, cost for

machining and appropriate for spinal support these criteria. Each idea was considered under

these criteria and if it was obvious that it was not good, it was no longer considered. The

evaluation would move on to the next one. If they did meet these criteria, the idea would be

marked and continued on for further review.

All of the following decisions were made with the help of morph charts found in

Appendix B. The team divided the concept into four main categories. To make the device be

adjustable, either mechanical or electrical control was designed. The team members made an

evaluation and due to the limited knowledge to the programming and the convenience for PT to

use, the team eliminated all the electrical control concepts. The team decided to use the

mechanical control by manual tools, make the back support to be adjustable.

For the support concept, the team members designed support for anterior, spinal and

lateral. Due to the concern of individual comfort and safety, the team eliminated the anterior

support since that may make the individual uncomfortable or have some potential risks. After

evaluating, the team decided to further look into spinal and lateral support later. Also the team

thought the different pieces would use removable and attachable cushion with springs and air

pockets in it.

24

For the back design, some members designed one-piece back support, some designed

two-piece back support--, upper and lower back support, and some designed multiple pieces. To

make the back support more suitable for the unique individual body shape, the team decided to

use the multiple pieces back support design, even though it may be cost more than other designs.

To attach the base, some concept used the idea that each piece uses one rail to attach the

back base while some others used a box to include all the rails. To make the back support more

adjustable in all directions- up / down, in/out, left/ right and different angles the team decided to

use the box enclosing both rails attached to the back piece idea.

After narrowing down the main categories, the group decided on the factors believed to

be significant to each component of the back support and each factor will be given a certain

weight as to how important it would be for the final design and production of the device.

Conceptual Design

Following the concept screening process, four proposed designs for the back support

were created including one piece air bag back support, and three pieces back support, one piece

attachable back support, and multiple pieces adjustable back support.

One piece air bag back support

The first alternative device model consists of 3 bag pockets on the back support, which

looks like the figure below.

25

Figure 11: One-piece air bag back support

The key factor in this alternative design is simplicity and thus the device is easy to install.

The characteristic of this back support is obvious which is to use three air bags to support lumbar

and lateral. People can change the stiffness of the back by changing the gas-filling degrees of air

pockets. The two air bags in the side can be filled air separately according to different people’s

favor. The three air pumps on the back are used to fill the air. The ribs on the side are used to fix

the sitting position, which protects against the person falling down from the side. The base of the

back support is attached to the rails so that the back can slide up and down on that rails. The

position of the back support can be changed manually through sliding the base on the rail and

then lock it by hand. The neck support is super adjustable which can be stretched back and forth

and also can go every angle.

Three pieces back support

In contrast to the initial primary design, the second alternative is a three pieces back

support rather than a whole piece back support, which can be found below.

26

Figure 12: 3 pieces back support

The user is convenient to change the shape and position of this back support by adjusting

pieces’ size and attaching position. According to different users’ height, the cushions can be

added and reduced. Also the cushions can be pasted to everywhere on the base. Users can change

the angle and in incline of the cushions as well as the order. There are various cushion shapes of

this back support in order to match up different users’ requirements. There is another place on

the lower back can attach a pad to support lumbar. The base of the back support is also attached

to the rails so that the back can slide up and down on that rails. The neck support is super

adjustable either. Users change the stiffness of the back support by changing different cushions.

One piece attachable back support

The third alternative design is one-piece attachable back support, which combines the

characteristics of first 2 devices. This back support is adjustable by changing the whole back

shape through exchanging different pieces.

27

Figure 13: One-piece attachable back support

There are lots of holes on the base, which are used to attach the different back cushion.

The same cushion can also be attached to different position by inserting in different holes so that

the cushion can move up and down. The cushions have different size in order to meet the various

users’ height. The curve shape in the lower back is used to support lumbar. The base of the back

support is attached to the rails so that the back can slide up and down on that rails. The neck

support is super adjustable.

Multiple pieces back support

The forth-conceptual design emerged as the strongest possibilities for fulfilling the

functional and clinical requirements. The design is multiple pieces back support.

28

Figure 14: Multiple pieces back support

The back pieces attach to the base with ball or socket joints, which make the pieces,

can rotate with different angles. The shafts connecting with the pieces are flexible that can

stretch out and draw back. Every piece is response for a kind of support including lateral

support, shoulder blade, middle back support, lower back support and neck support. Each

section can be adjusted to accommodate each individual. The base attachment is Center

location for insertion point of each pad. The stiffness of back pieces can be adjusted by

changing air pressure for harder or softer back.

Selection Process

In order to logically select the best mock up idea to be used in out system, we constructed

a design matrix. This matrix compared the four design concepts that we came up with. We

decided on a list of 10 criteria that the overall back rest design had to meet. There was a goal

29

established for each criteria, and the criteria were also weighed on a scale from 1 to 10. On this

scale, 1 is the least important and 10 is the absolute most improtant criteria. To get these

weights, each group member seperately ranked each criteria from 1 to 10 based on what they

thought was the most improtant. While weights were being assigned to each criteria, each group

member made sure to condiser the clinical advice that was received while doing observations of

physical therapists at Martha Moorehouse. One key aspect of this advice was that safety was of

the upmost importance. Above all else, the device must be safe for use. Another key point of

advice was that choosing a back support is a different process each time because each individual

has different neets that have to be met. Because of this variety, adjustability may play an

important role.

After each group member was finished, the rankings for each criteria were added up and

the criteria with the highest summed score received an importance weight of 10. Each group

members rankings, as well as the total score and overall established weight for each criteria can

be seen in Table 1, below.

30

Table 1: Ranking each criteria to obtain weight values.

As a group, each concept was then ranked, also on a scale from 1 to 10, based on how

well it met the specific criteria’s goal, with 1 showing that it did not meet the goal and 10

showing that it exceeded the goal. Many of these goals were determined when compared to

current products on the market and how well they met the requirents set forth previously. By

providing a 10, it is believed that the design will exceed requirments set forth as well as exceed

requirment when compared to all products on the market. A 1 would determine that all products

on market better complete the goal given goal and our product would be unable to. The goals

and scoring for each criterion are included in the matrix. A concept’s score for a criteria was

then calcuated by multiplying its rank by its weight. At the end of this process each concept’s

scores were added up and the highest score was chosen as the best design concept. The design

matrix can be seen below in Table 2.

31

Table 2: Design matrix used to compare the four design concepts.

First, safety was the most important criteria being considered in this project so we were

happy to see that all four concepts did relatively well when it came to individual safety. Because

of its many moving parts concept four scored the lowest in this category. The lower score was

due to more moving parts compared to current products on market. The products generally do

not contain this many moving parts.

Overall, the third concept received the lowest score partly because it was seen as the least

safe for physical therapists to use when making adjustments. The weight of each back support

cushion may become an issue, as the design requires the entire cushion to come on and off in

order for adjustments to be made. If the cushions are heavy, this increases the risk of injury for a

physical therapist. Also, the holes on the posterior of the back rest that are used for attaching a

cusion can be pinching points for a physical therapist when trying to attach the cushion. It also

32

may prove to be difficult and frustrating for a physical therapist to align the back of the cushion

with the desired holes, as the holes are not very big.

Next, it is important to note that concepts one, two, and three all scored low when it came

to adjustability. Concept one scored the lowest, mainly because the only way it could be

adjusted was vertically up and down. Concepts two and three scored better, but both did not

offer the high amount of adjustability that was desired. Adjustability was a larger consideration

for the project (with a weight value of 6, the only criteria above it dealt with safety and support),

so the lower adjustability scores for these three concepts showed that they may not be ideal

designs moving forward. Adjustability was determined based on current products. The products

we gave initial values to products and related our designs based on the adjustability to these

products.

With this in mind, concept four scored the highest in adjustability because of its many

moving parts and more modular design. Concept four also easily scored the highest when it

came to comfort and appropriate spinal support. This can be thought of, in part, as a result of its

high adjustability. Because of its many moving parts, concept four can be easily adjusted to find

a more comfortable position for the user if they are experiencing discomfort. Also, proper spinal

support can be achieved for individuals of many shapes and sizes with this concept because of its

high adjustability. This is ideal as no two people’s bodies are exactly the same.

Because of their relative lack of adjustability, the first three concepts also suffered when

it came to the comfort and appropriate spinal support criteria. If a user’s body type changes or if

they simply have become uncomfortable in their current position, these concepts offer only a

limited amout of help. Also, the pre-defined cushion shapes used in the first three concepts may

not be able to provide the amount of spinal support that a physical therapist thinks is necessary.

33

Again, no two bodies (and no two spines) are the same and these pre-defined cushion shapes are

limited in the amount of potential support and comfort they can provide.

Concept four did score poorly when it came to ease of use for the physical therapist.

Because of its many moving parts, it may take some time for the physical therapist to make

adjustments and find a good position for the user. This was not taken too heavily into

consideration because ease of use for the physical therapist was seen as a realtively low priority

criteria. Concept four’s high marks in categories such as adjustability were seen as more

important than ease of use. Also, it is important to note that the scoring for ease of use was

based solely on the number of moving pieces that the back support contained. The actual ease of

use for concept four could be improved with the implementation of a quick and easy system to

lock each piece into place, or unlock it so it can be adjusted.

In addition to the requirments proposed by the group after speaking with the clinicians

after the observation, we also compared these designs to the functional requirments set forth

previously. We determined that concept 4 was best able to provide the functional requirements

compared to the other designs. Concept 4 was easiest to fit various individuals by allowing the

pads to be placed where physical therapists deem them needed.

In conclusion, concept four’s ability to provde a taylored fit to a wide range of body types

allowed it to score the highest in categories such as adjustability, spinal support, and comfort.

This, along with its high marks in safety, ultimately resulted in it scoring the highest in the

decision matrix, and our final design concept reflecting many of the idea it used.

Description of Final Proposed Design

Our team had a unique route of the design process and coming up with our final design.

After our team had already created three mock-ups that were already very similar to designs on

34

the market, it was necessary to re-evaluate our functions we needed and come up with a more

groundbreaking design. We were encouraged by our mentors to look at the basic functionality of

supporting a person properly by sitting and falling limp and evaluate where support was most

needed to hold proper position. We spent a Sunday morning evaluating this process while

simultaneously taking into account the clinician’s feedback, mentor feedback, the concept map,

and both current market designs and our previous designs. The final screening process and

concept elimination can be found in Figure 15.

Figure 15: Final Screening Design

After the new design was finalized, we put it into the design matrix to evaluate if was

actually superior to the previous three mockups. It did have the highest score on the chart. Our

concept that we created has supports for each of the points on the upper body we determined

during re-evaluation of function. These supports will be padded with a small, inflatable air

cushion within it to increase or decrease compliance of the pad. Each of these pads will be

attached to a telescoping ball and socket joint on a thin central plate or bar so that it has a very

35

high number of positions it can be set in and accommodate nearly any back shape and still be

able to provide the proper support needed. These ball and socket joints will also be located on

the pad so that the angle of each pad relative to the back can be adjusted appropriately.

There is still much to be evaluated on these joints to ensure that they can be properly

locked into place. There will also be an available seatbelt attachment to prevent forward ejection

given an abrupt deceleration. Inherent in this design that is multiple, separate pieces is a large

increase in airflow; much more of the back is exposed to the environment allowing the body to

properly regulate temperature. Finally, a type of elastic, padded cover will be able to be placed

overtop of these individual supports so that there is a decreased risk of an individual migrating to

in-between the pads.

Figure 16: A set of sketches showing a potential final design

36

Figure 17: A figure showing the details of the pads and telescoping ball and socket joints

Figure 18: Front view of the Solidworks design mock-up

37

Figure 19: A side and isometric view of the Solidworks design mock-up

38

Chapter 4: Testing

Testing and Evaluation Plans

After researching, it was determined ISO 7176-1:2014 specifies test methods for

determining the static stability of wheelchairs. It is applicable to manual and electrically powered

wheelchairs, with a maximum speed of 15 km/h, intended to provide indoor and/or outdoor

mobility for one disabled person whose mass is no more than 300lb. Also, ISO 7176-1:2014 does

provide a method for the measurement of the tipping angles. For the first statics test, our group

wants to make sure that the back support will be able to support a person weighing up to 300 lbs.

It has been found that your upper body (from the waist up) accounts for about 65% of your total

body mass [14], so our back support needs to be able to support up to 195 lbs (300*0.65). To

test this, our group will first lean the back support slightly and put weight on the back support, to

see if it can support a mass of 195 lbs. Weight can be added through the use of items such as

sandbags with a known weight. The test will be deemed successful if it is able to hold a weight

of 195 lbs without any parts moving or failing.

Once completed, the group will test the wheelchair on a flat plane at a speed of

approximately 15 km/h, to determine if it is able to maintain a stable positon and meet the ISO

requirements. Afterwards, the wheelchair will be moved to a moving platform to determine the

tip angle, which is the position where the wheelchair force and friction can be cancelled. The

platform begins parallel to the ground and increases at small intervals (approximately 1 degree)

until it reaches a point where the wheelchair begins to move. A piece of paper, having the ability

to slide under the wheel, will be used to determine when wheelchair is no longer in full contact

with the ground. In addition to sandbag testing a group member’s father, at 6’ 5” and 300 lbs will

be able to test for the size requirements based on being near the top of our functional limits. The

39

weight is also able to be tested through sandbags; however, his height will allow the group to

determine if the pads are able to reach a person with a height of 6’ 3”. John and Nick will lead

this testing.

In addition, ISO 7176-8:2014 specifies requirements for static, impact, and fatigue

strength of wheelchairs. It specifies the test methods for determining whether the requirements

have been met. It also specifies requirements for disclosure of the test results. In this back

support project, the group needs to test the fatigue of the telescoping rods and pads. This will

determine if the wheelchair can support a person safely. Before this test, according to the

reference, the factor of safety for the wheelchair back support should be around 5. The design

yield stresses of the telescopes and pads are calculated by using the safety factor and the stressed

obtained from pressure mapping. The designed yield stress should be proportional or slightly

smaller than the true yield stress of the materials. However, the designed yield stress should be

much larger than the stress that a person actually places on the back support in order to ensure

safety. The test will require two team members who have different back sizes and weights to lie

on the back support at different angles. Three key factors need to be determined, including:

whether the telescoping rods and pads can reach every point needed to support the person,

whether the telescoping rods crack and whether the telescoping rods and pads vibrate a

significant amount which is deemed by visual conformation for approximately 30 seconds. If the

pads and telescoping rods can support these individual firmly, there are no cracks and the

telescoping rods do not show obvious vibration, the wheelchair back support is safe. If any of the

tests are unsuccessful, the dimensions of the telescoping rods and pads should be re-calculated.

The calculation and determination of material strength safety testing will be leaded by Jiahui and

Zhengdi.

40

In addition to things such as static and dynamic tests, the group wanted to conduct a

clinical evaluation of our device. To do this, we plan on taking our back support to Martha

Morehouse to have it tested and evaluated by therapists and potential users. These testing

sessions will be videotaped for subsequent analysis. Videotaping will allow us to view the

testing session multiple times, allow any absent group members to see what happened during the

testing session, and conduct further analysis on the tests at a later point in time. To help get

feedback, we will have both the therapist and user fill out a short survey after they are done

testing/using the back support. The functional requirements for our device were highly

considered when creating these surveys, as well as ergonomic requirements such as proper

lumbar support. Group members will take turns going to Martha Morehouse to get the survey

filled out, and we hope to get feedback from at least four different therapists and users. Alex will

lead this testing; once survey’s completed by group members he will gather and give initial

analysis to group members who will then determine changes needed to device. While the back

support is being tested, our group will provide as little assistance as possible to the therapists and

users in order to see how intuitive the device is to use and install. This will allow us to see parts

of the design that may be difficult to use or understand. Each test will require the completed

back support prototype, one therapist, one user, and two group members (one to observe and take

notes, and one to videotape the test). These tests and surveys are a good way to have the device

as a whole tested and will provide great feedback from the people who will actually be using the

back support. A sample survey for therapists and users can be seen in Figures 20 and 21, below.

41

Figure 20: Sample survey to be completed by a therapist after they have tested/used the device.

42

Figure 21: Sample survey to be completed by a user after they have tested/used the device.

43

These surveys will allow us to get initial reactions from the people whose opinion will

matter the most, the users and therapists. The surveys will help us assess the simplicity of the

design and see how difficult the device is to use compared to the back supports that are currently

on the market. The group will use the feedback from these surveys to make possible alterations

and changes to the design of our device.

Another significant test that we plan on implementing is the overall dimensions test as

explained by ISO 7176 Part 5. This plan tests the wheelchair to determine if it is around the

suggested dimensions of a wheelchair. The ISO defines no suggested size maximum, but a guide

defined a standard size as 28” x 51” x 43” (WxLxH) [15]. The test will start off with the chair

expanded to its maximum size (i.e. all telescoping arms will be let out all the way). Then, a tape

measure will be used to determine the dimensions in the X, Y, and Z directions. Three team

members will measure the dimensions, separately, three times using the same tape measure to

ensure the final dimensions are repeatable. These values will be compared to those defined in

the ISO. The device will meet the specification if it is smaller than four inches of the maximum

suggested dimensions for each given direction. This test will require the prototype back support,

the power wheelchair, a tape measure, and three of the six team members. Chris will head the

procedure and also take part in measuring.

A final test that we plan on performing is an incendiary test where we will determine how

flammable the material is that we are using for the wheelchair back pads [16]. This is in

compliance with ISO 7176 Part 16. The test is performed by pressing a lit cigarette to the

material and measuring how long it takes for the material to ignite. This test will be repeated 20

times, once for each cigarette in a pack. The device will meet the specification if it has times

equal to or lower than the value defined in the ISO. This test will require a pack of cigarettes, 20

44

pieces of the material used for the padded cover (all of equal size), a lighter, and a stopwatch.

Chris will head this test.

Device Evaluation and Analysis

Clinical Evaluations

A working mock-up of the back support was brought to Martha Morehouse in order to be

evaluated by Physical Therapists. The mock-up was not yet in working condition, but the

therapists were still able to see and evaluate the device at full-scale. They were given a brief

overview of the device, the reasoning behind its design, and a short demonstration of how the

telescoping rods and ball-and-socket joints worked. The therapists were then asked to fill out the

Therapist Survey (Figure 20) in order to provide feedback on the design. A total of 14 therapist

surveys were completed and analyzed. Because the mock-up was not yet in working condition,

the original plan for conducting the clinical evaluations (including getting feedback from users)

could not be used.

After evaluating the feedback from the surveys, it was noticed that the therapists had

issues with two major components of the design: the length of the telescoping rods and the

strength of the ball-and-socket joints. Many therapists believed that the telescoping rods on the

device were too long, and showed concern that the back support therefore may not fit on a power

wheelchair. The rods were later shortened considerably (to about half of their original length) in

order to correct this problem. Also, many therapists were concerned that the locking mechanism

for the ball-and-socket joints would not be strong enough for the pads to stay in place while

supporting weight. This was also a main concern within our group, and static tests were

conducted in part to test the strength of these joints.

45

Engineering/Static Tests

In order to assess the ability of the device to provide numerical output, Jiahui Liu will

push on the force measuring component of the wheelchair back with her body. Zhengdi Wang

will observe the device to verify that it has provided a reliable output.

1. Stability Testing

Static stability was measured according to the methods of the International Organization

for Standardization. ISO 7176-2014 must be valid in order to ensure that the device is able to

withstand the strength of the target population. The standards state that the device must stay

stable while the wheelchair is moving under 15 km/h. In this case, the focus of this test was on

how the different speeds, loads and directions affect the stability of the wheelchair back.

In order to analyze the function, the wheelchair back was tested on a flat at constant

speeds of 0, 5, 10 and15 km/h with different people weights on the wheelchair including 0, 110

and 150 lb. The device was set up as shown in figure 22. Also the wheelchair back was tested for

forward and rear stability at various mass loads with no speed. Forward and rear indicates the

wheelchair faces downhill and uphill respectively. The results showed if the multiple telescoping

rods and pads were able to stay locked in one place.

46

Figure 22: Stability tested Device

The results are shown in Table 3 and Table 4. Table 3 shows how the speeds and loads

affect the stability. Table 4 indicates the wheelchair stability under different moving conditions.

The test result is not very reliable due to the fact that the ball and socket joints were not able to

be tightly locked into place. This resulted in a poor stability of the wheelchair back support.

Table 3: Results for the stability test under various moving speeds

47

Table 4: Results for the stability test under various directions

The results demonstrate that the stability gets worse while the wheelchair speed and mass

load increasing. The forward stability is better than rear stability. However, from the results

above, it is obvious that the wheelchair back is not stable due to the inability of the ball and

socket joints to lock properly. In conclusion, the stability test was not successful.

2. Fatigue test

ISO7176-8-2014 specifies requirements for static, impact and fatigue strength of

the wheelchairs. The fatigue test is used to determine if the wheelchair back can support a person

safely for a long period of time.

From the stability test, the wheelchair back cannot support a person stably. So the test

cannot be done as planned (two team members who have different back size and weight lie on

the back support at different angles). In order to do this test, first, the maximum stress was

determined by using a pressure map, shown in the figure 23. As shown in the figure 23, the

maximum stress was on the shoulder pad. The pressure is 50 mmHg.

50 = 6.7 kpa

According to the dimension of the shoulder pad, the maximum force on the shoulder pad should

be

48

𝐹 = 𝜎𝐴 = 6.7 ∗ 0.104 = 696.8𝑁

𝑀 =𝐹

𝑔=

924.6

9.8= 71.1 𝑘𝑔

So, the shoulder pads and rods should be able to hold a mass of 71.1 kg.

Figure 23: Result of pressure mapping

For this test, the whole back piece was placed on a table and then weight was added to

each rod respectively. Table 5 shows the maximum mass that each rod can hold without bending.

Table 5: Results for fatigue test for each piece

The rods are tested without connection to the ball and socket joints. The test results may

be different if they are connected. However, if the rods and pads connect to the socket and ball,

the socket and ball will fail before the rods begin to bend. The maximum mass load the pads can

hold with connection to the ball and socket joints is 10 kg.

49

From the test result above, the maximum mass load the shoulder pads can hold is a little

smaller than what is calculated before, which means the shoulder rods may crack when the

person lies on the back. The material of the shoulder rods will need to be replaced to a stronger

one.

Dimensions Testing

The device was measured according to the 7176-5 standard. The wheelchair base is

made by Quantum. The power wheelchair was tested at Bevis Hall BH, Building 307, 1080

Carmack Rd, Columbus, OH 43210. There is not a pass/fail requirement for this standard as it is

mainly used for comparing different wheelchair specifications. Also, as only the wheelchair back

is being exchanged, many of the dimensions, mass values, and turning radii are equal to the

original manufacturer’s specifications. During testing, there were a couple deviations from the

procedure outlined in the standardized test including arm rests and a head rest that had not been

installed as there were none available at the time of testing.

The device measured only five inches wider than the original power wheelchair base with

no arm rests installed with all portions fully extended to be 27 inches wide as displayed in Figure

24.

50

Figure 24: Depicting overall width of the wheelchair when fully extended

The overall height of our wheelchair including the base was 42.125 inches tall as

displayed in Figure 25.

27”

51

Figure 25: Depicting overall height of the wheelchair when fully extended

The overall length of our wheelchair was unchanged from the original length at 50.5

inches as displayed in figure 26.

42.125”

52

Figure 26: Depicting overall length of the wheelchair when fully extended

Again, as there are no pass/fail requirements for this test, the test has complied with the

standard and can be reported with the wheelchair information when being sold.

Ignitability Testing

The following test results relate only to the ignitability of the combination of materials

under the particular conditions of the test. They are not intended as a means of assessing the full

potential hazard of the finished wheelchair. The test samples included two pieces of foam both

covered in the selected, elastic-based material. The test took place on 04/19/2015 at Bevis Hall

BH, Building 307, 1080 Carmack Rd, Columbus, OH 43210. The test does conform to the ISO

7176-16 standard test procedure. This defines the size of foam material to be used as follows in

Figures 27-28:

50.5”

53

Figure 27: Sizes of foam specimens from ISO 7176-16

Figure 28: Vertical section through test rig assembly for foam specimens from ISO 7176-16

During ignition safety testing, the smoldering cigarette was able to ignite both the cover

material and the foam. The device does not comply with the ISO 7176-16 standard: resistance to

ignition. It is suggested that future devices should use ignition resistant covers and foam to

prevent future injury and abuse of the device. Images of the results are as follows in Figures 29-

31:

54

Figure 29: Initial burning of the cigarette end

Figure 30: Result of continued smolder of foam and cover

55

Figure 31: Result of the cigarette testing on the foam

56

Chapter 5: Conclusion

Summary

The Adjustable Back Support was designed to assist individuals with desired anatomical

positioning while maximizing their quality of life. The design was created in order to address the

current limitations of the back supports that are on the market. Back supports have been found to

be either too simplistic with no adjustability for many individuals, customized for one individual,

or contain the ability to adjust after tedious and difficult work form the therapists fitting the

device. The goal of this device is to fit various body types, such as a customizable wheelchair

back, but will be easier and less time consuming to adjust. By creating a device that is

adjustable it allows many individuals to use the device and allows the back to be customized to

different individuals. Currently there are marketed products that complete this, discussed

previously in this report, but they are very difficult and time consuming to use. This device

solves the current limitations through:

Latch-Locking Telescoping Rods

Locking Ball and Socket Joins

Multiple Pad Supports

Curved Surface Features to allow more comfortable fitting to individual body

These key characteristics of the device allow simplicity while providing exceptional

adjustability to fit many shapes. An image of the device can be viewed below.

57

Figure 32: Final Design of Device

As seen above our device is attached to the base of the power wheelchair and contains

telescoping rods which use latch locking mechanism that will extend the individual pads outward

to adapt to different heights and widths of individual. The ball and socket joints on each end of

the telescoping rods allows for placement of pad in various orientations. Pads are curved

allowing for simplistic fitting to individual. This design will be fully covered by a cloth sheet

that contains a foam pad to provide comfort to the individual. This design ultimately provides the

back support the customizable ability while still being simple to use.

Improvements

After completion of prototype there was several modifications that are needed to produce

a better device. We would deem our device a success but believe the device could be created

better with another few months of redesign and testing. Our group also believes that this redesign

58

would allow for more successful engineer testing which would need to be collected before

deciding to pursue marketing the device.

Overall we would create the back support to be more aesthetically appealing through

altering the design of the cloth pad that covers the individual pads. In addition to this, alternate

material would be chosen that would be biocompatible if in direct contact with tissue for

extended periods of time and would material would be able to withstand cigarette burn test. By

choosing a material that is biocompatible it increases safety for the individual. Currently the

material that was chosen for the device was woven cloth due to its ability to resist fraying form

common forces. The design of the padded material would be more aesthetically pleasing to assist

in increasing the marketability of the product. B

Secondly the ball and socket joints would be altered. The ball and socket joints that are

currently on the product are plastic based and were found to not be strong enough to hold the

pads in their intended positions. When the pads where perpendicular to the base of the socket

portion, it was found the weight caused the ball and socket to move from its locked position. In

order to fix this for the prototype, the locking portion was drastically tightened with the help of

pliers. Additional methods to tighten the locking mechanism included, adding material into the

vacant area between the ball and socket, roughening the material in contact with each other, and

Attempted angle placement of the pads when locking. To improve this portion the group would

look further into alternative locking methods or manufacture a ball and socket mechanism from a

CNC machine. The group has been unsuccessful in finding current locking ball and socket that

would fit this groups intended need and believe this would be a vital improvement to the design.

By increasing the strength of the ball and socket, the design could be further tested to ensure

additional weight can be supported with the user.

59

The third item that would be altered would be the telescoping rod mechanisms. Even

though these positions of the device did not fail directly during physical testing due to ball and

socket failure, the group believes that they should be strengthened. Strengthening the clasp that

locks the telescoping mechanism in place would increase the added strength. Current methods to

tighten the clasp included adding material into the vacant space. We believe if the clasps were

made of a stronger material, the telescoping rods may be more beneficial.

Our group would deem this project a success even though there are several attributes that

need to be altered before moving forward. Our group believes there are several altered items that

can be quickly inserted into the current design. One thing the group may consider in future

designs in addition to the added items above would be decreasing the size of the device for

aesthetic reasons. We believe that if the project had 3-6 more months then a product would be

produced that could be marketed and compete with current devices.

We believe individuals worked well together but there would be a few items that would

be changed if we could start a new project today. One change would be to have weekly meetings

that are scheduled to ensure all members are completing their work. This was followed the first

semester but during the second semester the group decreased meetings in person. A second

change would be have members individually take responsibility of subprojects instead of having

the entire group working on all project at the same time. Finally the group would work on setting

due dates ahead of time and having individuals follow these due dates through the entire project.

If the due dates were followed then the project would have been completed quicker and stress

from communication skills would have been decreased. Finally we would have taken additional

time in choosing an innovative design. The group believes we have chosen a successful design

but if we could start over we wished we focused more on the concept screening process.

60

Conclusion

There are about 12,000 spinal cord injuries that occur every year and individuals

who suffer from thoracic and cervical spine injuries will have impairment of the trunk and core

muscles, which results in impaired postural control. Many of these individuals will need to

utilize a power wheelchair, and the back support of the chair is a key aspect in providing proper

support and comfort to the user. Many power wheelchair back supports on the market today are

simply a single foam pad, with limited adjustability. There are also some back supports that can

be molded to fit a specific user, but these supports cannot be adjusted once the mold has set.

Some support that are able to meet this clinical need have over 100 moving parts, but making

adjustments to theses is a time-consuming and tedious process. We aimed to create an

adjustable, customizable back support for power wheelchairs that is simple to use and quick to be

adjusted. We accomplished this by creating a back support with 8 adjustable pads that are

attached to a back plate with telescoping rods and ball-and-socket joints. The telescoping rods

and ball-and-socket joints allow the back support to be adjusted to a wide range of positions.

The back support is able to be customized for a specific user, and slight day-to-day adjustments

can be made quickly and easily. This means that if, at any time, the user becomes uncomfortable

or the clinician does not think that the user is being supported well enough, adjustments can be

made quickly.

61

References

[1] "Product Classification." Product Classification. The Food and Drug Administration, n.d.

Web. 1 Dec. 2014.

[2] Bernhard M, Gries A, Kremer P, Böttiger BW. Spinal Cord Injury (SCI) – prehospital

management. Resuscitation. 2005;66:127-39

[3] Pride Mobility Products Corp. N.p., n.d. Web. 25 Oct. 2014.

[4] Zollars, Jean Anne. Special Seating: An Illustrated Guide. Minneapolis, MN: Otto Bock

Orthopedic Industry, 1996. Print.

[5] Mirzaie, Mehdi, Jonas Jahkel, Niklas Backstrom, Urban Lind, and Bo Engman. Wheelchair

Backrest Assembly. Permobil Ab, assignee. Patent US8596719 B2. 3 Dec. 2013. Print.

[6] Blauch, Corey M., George A. Turturiello, and Michael J. Rozaieski. Reclining Seat With-

Shear Adjustment. Pride Mobility Products Corporation, assignee. Patent US 7296856

B2. 20 Nov. 2007. Print.

[7] "Standards." AAMI: Publications:. N.p., n.d. Web. 31 Oct.

2014.http://www.aami.org/publications/standards/biotcd.html

[8] "Standards." ANSI: Publications: N.p., n.d. Web. 31 Oct.

2014.http://ansidotorg.blogspot.com/2009/08/assistive-device-standards-

for.html#axzz3HhC76YGv

[9] Human factors engineering guidelines and preferred practices for the design of medical

devices. (1989). Applied Ergonomics, 20(2), 145. doi: 10.1016/0003-6870(89)90142-7

[10] "The Kinematics of Sitting: Ergonomic Criteria for the Design of the Aeron Chair." The

Kinematics of Sitting – Research – Herman Miller. N.p., n.d. Web. 12 Dec.

62

2014.http://www.hermanmiller.com/research/solution-essays/the-kinematics-of-

seating.html.

[11] "Kyphosis." Kyphosis. N.p., n.d. Web. 12 Dec.

2014.http://www.spineinstituteny.com/conditions-a-

diagnosis/conditions/kyphosis.html#symptoms.

[12] "Matrix Seating." Matrix Seating. N.p., n.d. Web. 29 Nov. 2014.

<http://www.matrixseating.com/images/matrix-easy-fit-back-wheelchair_cropped-

resized.jpg>.

[13] "Shepherd Center." Learn About Spinal Cord Injuries. N.p., n.d. Web. 12 Dec.

2014.http://www.shepherd.org/patient-programs/spinal-cord-injury/about.

[14] Plagenhoef, S., Evans, F.G. and Abdelnour, T. “Anatomical data for analyzing human

motion.” Research Quarterly for Exercise and Sport 54, 169-178. Web. 9 Mar

2015.http://www.exrx.net/Kinesiology/Segments.html.

[15] Mclaurin, Colin A., ScD, and Peter Axelson, MSME. Wheelchair Standards: An Overview

(n.d.): n. pag. Web. 9 Mar.

2015.<http://www.rehab.research.va.gov/mono/wheelchair/mclaurin2.pdf>.

[16] "ISO 7176 Part 16: Fire Test of Upholstered Parts_Ecosafene." ISO 7176 Part 16: Fire Test

of Upholstered Parts_Ecosafene. N.p., n.d. Web. 09 Mar. 2015.

63

Appendix A: Selected Sketches

Figure 33: Initial concept designs obtained from each group member. (Click on object to open up .pdf file of

full concepts)

64

Figure 34: Initial concept designs obtained from each group member. (Click on object to open up .pdf file of

full concepts)

65

Figure 35: Initial concept designs obtained from each group member. (Click on object to open up .pdf file of

full concepts)

66

Figure 36: Initial concept designs obtained from each group member. (Click on object to open up .pdf file of

full concepts)

67

Figure 37: Initial concept designs obtained from each group member. (Click on object to open up .pdf file of

full concepts)

68

Figure 38: Initial concept designs obtained from each group member

69

Figure 39: Initial concept designs obtained from each group member

70

Figure 40: Initial concept designs obtained from each group member

71

Figure 41: Initial concept designs obtained from each group member

72

Figure 42: Initial concept designs obtained from each group member

73

Figure 43: Initial concept designs obtained from each group member

74

Figure 44: Initial concept designs obtained from each group member

75

Figure 45: Initial concept designs obtained from each group member

76

Figure 46: Initial concept designs obtained from each group member

77

Appendix B: Morph Charts

Table 6: Morph chart for Adjustability

Component or function Concept 1 Concept 2 Concept3

Adjustability Electrical Programming Switch X Mechanical Dial Lever Manual tools

Table 7: Morph chart back piece

Component or function

Concept 1 Concept2 Concept 3

Back piece

One piece

Piece sliding Modular X

Two piece

Upper/ Lower piece sliding

x x

Multiple Pieces

Multiple piece sliding like a

table top

Many adjustable pieces, can adjust

individually

Pieces can be expanded in all directions to a larger one

Table 8: Morph Chart for Base attachment

Component or function Concept 1 Concept 2

Base attachment Attachment alone each rail

Box enclosing both rails attached to the back piece

Table 9: Morph Chart for Support

Component or function

Concept 1 Concept2 Concept 3

Sup

po

rt

Anterior Roller coaster bar

Seat belt strap Strap across chest

Spinal spring Air pocket Removable/attachable cushion

Lateral Air pocket Cushion x

78

Appendix C: Large Concept Map

Figure 47: Large Concept Map

79

Appendix D: Assembly Instruction Manual

Disclaimer:

The following instructions describe the mechanical process required to assemble the back

support for Q6 power wheelchair. They do not describe the necessary steps to accommodate the

ergonomic requirements for the individual doing the assembly. Each individual should be

conscious of the need to remain safe during lifting and bending

Overview:

Assembling the back support for the Q6 power wheelchair involves putting together the base

plate, the ball and socket, the telescope, the different position support pads, different sizes of

connection piece between socket and telescope and cover cushion. Before beginning the

assembly process, be sure that you have all of the required tools and equipment and that all of the

contents listed below are present.

Contents:

Base plate – 1

Ball and socket—18

Head support pad – 1

Shoulder support pad-2

Middle back support—1

Middle side support—2

Lower back support—1

Lower side support—2

80

Screws for ball and socket –36

Ball and socket nut--36

Back attachment screws—16

Back attachment nut--16

Connection piece--18

Cover cushion---1

Required equipment:

Wrench –1

Screw driver

Assembly step:

1. Separate all pieces into individual groups including telescoping rods, pads, and ball and

socket attachment pieces (these items appear cylindrical with one side open)

2. Determine the size correlation of the connection pieces and the telescoping rods

a. Rods contain different diameter pieces and each piece should have one connection

piece that it press-fits into

b. Rods will be labeled to assist in location

3. Place all the connection piece on to the telescopes by twisting the piece while pushing

items together

4. Attach each pad to matched telescope; use the screw driver to tighten the screws and use

the nut to make the socket and pad attached

a. Pads will be labeled to describe location of pads

81

5. Attach the telescopes to the base plate, use the screws and nut to lock

6. Attach the whole back support to the wheelchair, use the suitable screws

a. Part comes attached with angle beam already connected so attachment onto

wheelchair can be used with screwing device into base

7. Place electrical control part back to make sure the whole wheelchair can be worked in

power mode

a. If required, if no electrical controls than can ignore this step

8. Adjust the back pads in order to hold the individual’s back stable and lock the ball socket

9. Place the cushion over pads to finish

82

Appendix E: Instructions for Patients and Clinicians

Disclaimer:

The following instructions describe the overall process required to set up and use the

adjustable wheelchair back support. During each of the steps, take all possible precautions to

ensure that the safety of the user is the first priority. The following steps assume that the user is

comfortable with the back spinal support and will not move around.

Overview:

Using the adjustable back support involves getting the device into position and stabilizing it..

The overall purpose of the process is to put the individual onto the wheelchair and adjust the

back support following the individual’s spinal shape. Before beginning to use the device, ensure

that the wheelchair is within reach, and ensure that the user is comfortable with the adjustment

process

1. Place wheelchair into position and let the individual sit on the wheelchair

2. Allow the individual rest against the back pads

3. Move pads into determined location by adjusting the ball and socket joints.

a. Shoulder should be located slightly under shoulder blades

b. Middle of the back piece should be present on middle of spine

c. Side pieces present several inches below individuals arms pits

d. Lower back piece several inches above iliac crest

e. Lower lumbar support should be placed where appropriate

4. Place pads against individual’s back by using telescoping rod to extend rods

83

a. Open the rod latch

b. Move rod to desired length

c. Close latch to lock into place

5. Observe individuals sitting posture

6. Repeat steps 3-5 until therapist desired posture is obtained and individual is

comfortable

84

Appendix F: Dimensioned Engineering draft drawings

Figure 48: The Mid side bolsters. There are two of these, one is simple upside down on the opposite side.

85

Figure 49: The ball of the ball and socket joints with telescoping rods

86

Figure 50: The stainless steel backplate

87

Figure 51: The lower side pieces. As with the mid side, there are 2 of the same just mirrored on the other side

88

Figure 52: The mid-mid support piece

89

Figure 53: The lower mid support piece

90

Figure 54: The L-bar that connects the stainless steel back to the wheelchair

91

Figure 55: The shoulder supports. As with the mid-sides and lower sides, there is two copies of the one

version, just upside-down

92

Figure 56: Final Solidworks rendering - side

93

Figure 57: Final Solidworks rendering - front

94

Figure 58: Final Solidworks rendering - iso

95

Figure 59: Final Solidworks rendering - top

96

Appendix G: Bill of Materials Table 10: Bill of Materials

Store Date Part Name Quantity Cost

Curbell Plastics 2/23/2015

24x48 inch HDPE (0.25 inch

thick) 4 $20.50

Pro.Fit

Inernational 3/4/2015 BRAVO Ball & Lock Plate 18 $11.95

Lowes 3/30/2015

24x24 inch16 Gauge Stainless

Steel 1 $20.15

Lowes 3/30/2015 3 foot 2 inch angle iron 1 $12.86

Lowes 3/30/2015 3/4 inch Screws/Washers 1 $5.58

JO-ANN Fabrics 4/2/2015 3/4 inch non-roll elastic 1 $2.99

JO-ANN Fabrics 4/2/2015 Half inch Non-roll elastic 1 $3.99

JO-ANN Fabrics 4/2/2015 250M Black Sew Spool 1 $3.99

JO-ANN Fabrics 4/2/2015 Fabric 1 $10.31

Target 4/2/2015 Camera Tripod 1 $35.19

Lowes 4/2/2015 5/16 inch Washers 1 $5.50

Lowes 4/2/2015 8/32 inch screws/washers 1 $5.58

Lowes 4/22/2015 Surface Cleaner 1 $8.78

Lowes 4/22/2015 Paint 2 $3.88

Total

$419.78

*Other materials used in this project were obtained from the Biomedical Engineering Senior

Design Build Rooms that were remains of previous year’s projects, material that was already

present on the group given wheelchair, or materials that group members previously had.

97

Appendix H: Final Budget

The total amount spent to develop a single prototype was $303.66. This items that were used in

the development of one single prototype model includes:

2x4 foot Sheet of 0.25 inch HDPE (1)

Camera Tripod (2)

Cloth Material (1)

Foam Pad (1)

Ball & Socket Locking Joints (16)

2 x 2 inch 1/8 inch Stainless steel sheet (1)

½ inch non-roll elastic (1)

8/32 inch screws/washers (64 Pieces)

2 inch Angle Iron (1)

Black Sewing Spool(1)

Flat Black Paint (1)

¾ inch long Hex Screws (4)

3/2 inch long Hex Screws(2)

Not all items used in the prototype have been purchased and have been remains from previous

years or group members owned. For this reason the cost of a single prototype may be slightly

higher than stated above but would remain under a $400 cap.

Note: Pieces used in this estimate are whole piece price but only portions of the piece were used

in the design (for example: only half of the 2x2 foot steel sheet was used in prototype but the

entire price was included in the above estimate). It should also be noted that nearly 2/3 of the

price for this design was due to locking ball and socket pieces with reduction of this portion the

entire prototype could be built cheaper.

98

Appendix I: Actual Timeline of Build (Final 3 Months)

Table 11: Timeline Items

Lead Start End

Product Design Entire Group 2/1/2015 2/8/2015

Material Selection (Plastic) Entire Group 2/9/2015 2/11/2015

Prodcut Ordering Plastic John Buddenberg 2/12/2015 2/23/2015

Design (Telescope Rod) Entire Group 2/16/2015 2/20/2015

Product Ordering (Ball and Socket) Chris Wasco 2/20/2015 3/4/2015

Develop Testing and Valadation Plan Entire Group 2/21/2015 2/25/2015

Refine and Further Detail Testing Alex Weber 2/26/2015 3/4/2015

Deseign Purchase Search (Telescope Rods

Jiahui Liu and Zhengdi Wang 3/5/2015 3/20/2015

Product Redesign (Telescope Rod) Entire Group 3/21/2015 3/25/2015

Product Purchase (Telescope Rod and Metal)

John Buddenberg and Alex Weber 3/26/2015 4/2/2015

Product Build Entire Group 3/30/2015 4/16/2015

Poster Preparation (PT) Alex Weber and Nick Hohman 4/6/2015 4/10/2015

Clinical Testing Nick Hohman 4/8/2015 4/8/2015

PT Presentation Nick Hohman 4/11/2015 4/11/2015

Design Testing Entire Group 4/13/2015 4/21/2015

Report Preparation Entire Group 4/22/2015 4/28/2015

Poster Preperation (Engineering) John Buddenberg 4/25/2015 4/26/2015

Design Showcase Entire Group 4/28/2015 4/28/2015

Report Submission Entire Group 4/30/2015 4/20/2015

99

Figure 60: Final Timeline Gantt Chart