1. A Walker With Integrated Toilet Seat and Stroller Capabilities
for the Disabled
By
Connor Moelmann
Master’s Committee:
Professor Albert J. Shih, Chair
Dr. Dick Sarns, Sponsor

2. 2
Acknowledgements
I would first like to thank my advisor, Professor Albert Shih. Professor Shih has helped
guide me through my Master’s program at Michigan, helped me obtain my GSI position for ME
250, which has paid my tuition at the university, and also been a leader with my thesis helping
guide my project down the right path.
I would also like to thank Dick Sarns, who is the sponsor of this walker project. The
walker was originally Dick’s idea and he has also helped guide this project to potentially become
a product on the market. I also want to thank Dick for funding the entire project including the
patent on the walker.
Next, I want to thank Kyle Happy, Jonah Shapiro, and Corwin Stout who helped me with
the original walker design in Winter 2011. I also want to thank Alex Pham, Phillip Davis, David
Wobith, and Josh Getz for helping design and manufacture the walker in Fall 2012.

3. 3
Table of Contents
List of Figures………………………………………………………………………………..4
Abstract………………………………………………………………………………………6
Chapter 1 – Introduction……………………………………………………………………..7
Section 1.1 – Information Sources…………………………………………………...8
Section 1.2 – Project Description…………………………………………………...11
Chapter 2 – Design of the Walkers…………………………………………………………13
Section 2.1 – Functional Requirements and Engineering Specifications…………..13
Section 2.2 – Alpha Design………………………………………………………...15
Section 2.3 – Alpha Design Feedback……………………………………………...17
Section 2.4 – Beta Design…………………………………………………………..17
Chapter 3 – Validation………………………………..……………………………...……..24
Section 3.1 – Framework…………………………………...…….…………………24
Section 3.2 – Handles……………………………………………………………….26
Section 3.3 – Foot Pegs……………………………………………………………..27
Chapter 4 – Feedback and Improvements…………………………………………………..28
Section 4.1 – Survey Questions……………………………………………………..28
Section 4.2 – Elderly Feedback………………………………………….………….32
Section 4.3 – Nursing Feedback……….……………………………………………36
Section 4.4 – Future Improvements………………………………………………...37
Chapter 4 – Conclusion…………………………………….………………………………..40
Appendix A – Bill of Materials……………………………………………………………...41
Appendix B – Manufacturing……………………………………………………………….42

4. 4
List of Figures
Figure 1: A bedside toilet commonly used in hospitals for immobile patients (p. 10)
Figure 2: Guardian Onvoy 480 before modifications (p. 15)
Figure 3: Guardian Onvoy 480 after modifications (p 15)
Figure 4: Using the alpha prototype as a stroller pushing from behind the user (p. 16)
Figure 5: Using the alpha prototype as a stroller pushing in front of the user (p. 16)
Figure 6: The Mini-Mack walker before modifications (p. 18)
Figure 7: The beta design can be used as a chair or stroller (p. 18)
Figure 8: The beta design has a built-in toilet seat to be rolled over a toilet (p. 18)
Figure 9: The backrest can fold down for increased visibility while walking (p. 18)
Figure 10: New rear cross bar of the Mini-Mack (p. 19)
Figure 11: Underside of the built-in toilet seat (p. 20)
Figure 12: The office chair modified for the walker (p. 21)
Figure 13: The walker’s hinge allows the toilet seat, cover seat, and backrest to rotate (p. 22)
Figure 14: CAD model of the hinge (p. 22)
Figure 15: A front view of the hinge as well as the additional frame support added (p. 22)
Figure 16: CAD model of the foot peg and the bracket (p. 23)
Figure 17: Actual foot peg and bracket is located 0.5” from the top of the wheel bracket (p. 23)
Figure 18: Finite element analysis proves the frame support will not fail (p. 24)
Figure 19: Finite element analysis proves the rear cross bar will not fail (p. 24)
Figure 20: Validation of the walker’s seat and frame (p. 25)
Figure 21: Validation of the walker’s additional handles (p. 25)
Figure 22: Validation of the walker’s backrest (p. 26)

5. 5
Figure 23: Validation of the walker’s handle with a sideways force (p. 26)
Figure 24: Validation of the walker’s handles with an inclined force (p. 26)
Figure 25: Validation of the walker’s handles with a declined force (p. 26)
Figure B1: Drawing of the rear crossbar (p. 42)
Figure B2: Drawing of the hinge wall (p. 44)
Figure B3: Drawing of the foot support block (p. 46)
Figure B4: Drawing of the extra handle (p. 47)
Figure B5: The walker’s extra handle (p. 47)

6. 6
Abstract
With the baby boomers reaching retirement, we anticipate a large increase in demand of
health care products for the elderly. As people age, bones become fragile and balance becomes
impaired, which puts older people at increased danger with longer recovery times. Dick Sarns,
the sponsor of this project and co-founder and CEO of NuStep, a rehabilitation equipment
manufacturer, wanted to create a walker for his wife, Norma Sarns, who suffers from multiple
sclerosis.
From interviewing Norma and many other elderly people in nursing homes, we quickly
discovered each person has unique situations and requires specific treatment. For example, one
may use a walker because he is recovering from a hip replacement while another uses a walker
because she has poor balance. Also, the dependence on the medical devices varies greatly from
person to person. For example, one person may only use the walker when walking great
distances while another can’t even stand up without a walker.
The project was designed for Norma, who is more disabled than the average person we
interviewed. Therefore we targeted our walker for a more handicapped person who is between a
walker and wheelchair and requires some assistance from a second person from time to time.
Continuing our research, we discovered most accidents occur in the restroom from tricky
maneuvers required to position one’s self above the toilet. On many occasions Dick Sarns had to
rescue Norma from the restroom because she could not get up alone. Therefore the primary goal
of the walker was to improve bathroom safety and comfort. The second goal of the project was to
be able to use the walker as a stroller if needed so the user could sit and be pushed around by a
second person. This walker will help transition a person from a walker to a wheelchair and can
also be used in hospitals to help bed-ridden patients use the restroom.

7. 7
Chapter 1 – Introduction
The walker is a tool used by the elderly and disabled to increase mobility, stability, and safety.
The walker was invented in the 1940’s by Andrejs Muiza, a Russian immigrant to the United
States. The first walker was made of solid iron and could not be adjusted to the user [1]. Since
then, there have been hundreds of variations of the walker made available to the disabled.
Elderly people are often weak and fragile which makes the most common tasks such as a
walking around the house hazardous. Falling is the leading cause of injury for elderly people [2].
Approximately one third of people over 65 years old fall every year, with about 10% resulting in
bone fracture and on rare occasions, death. Minor falls result in bruising but more importantly a
fear of falling and a loss of confidence in walking. Elderly people fall due to poor balance,
vision, and dementia, often times which are side effects from medications [3]. The walker helps
prevent falling by letting the user stabilize themselves with his or her hands and arms while
allowing the feet to move normally without obstruction.
Most accidents occur in the home, and the majority of these are falls that occur in the bathroom
[4]. Using the restroom can be challenging for a senior citizen because he or she will have to
maneuver to the toilet, balance only on his or her feet to rearrange clothing, and lower
themselves onto the toilet. Raised toilet seats and handlebars may be purchased to help senior
citizens use the toilet. However, not all bathrooms are user-friendly to the disabled. In many
houses, the first floor has a small powder room, which is not large enough to fit a walker in,
while the larger restrooms are located on the second floor are inaccessible [5]. Also, public
restrooms are not always handicap accessible and the floors are often wet and slippery.

8. 8
Dick Sarns, the sponsor and creator of this project, has asked for a walker suited for his wife,
Norma Sarns, who suffers from Multiple Sclerosis. Norma depends greatly on walking aids and
it between a walker and wheelchair for everyday activities. Therefore, we designed and built a
walker for someone of Norma’s condition and stature. In this paper, I will describe our initial
surveys to highlight the key features of the walker. Then I will explain the goals of our prototype
walker, the engineering specifications, how we manufactured the two walker prototypes, the
results of the final survey, and the future of the project.
Section 1.1 – Information Sources
As healthy young adults, none of the undergraduate students who worked on this project or
myself have had experience using a walker. While we could study the mechanics of the walker,
the ways it could be used, and how it could be transported, we could not simulate what it meant
to rely and be fully dependent on the walker. Therefore, we interviewed 16 senior citizens,
including Norma Sarns, using a 40-question survey to get the opinion of people with firsthand
experience with walkers.
From the interviews we learned each person is unique in terms of age, size, mobility, and
especially the reason for using a walker. These reasons ranged from weak muscles, hip problems,
knee problems, recovering from recent surgeries or accidents, poor balance, and more. Each
person wanted to feel normal and be as active as possible, preferring to use a walker to a
wheelchair. Most had only one walker, which they used for all of his or her tasks. For example,
they use the same walker for going to the bathroom, walking around the house, travelling, etc.
People who were more dependent on a walker typically had rolling walkers while those who

9. 9
were recovering from surgery or were relatively mobile used the basic folding walker. Everyone
felt much safer using the walker. Also, they rarely used the walker while sitting down or standing
up, instead they used the chair, couches, or other sturdy furniture for support. In the restroom,
more dependent people like Norma would bring the walker to the toilet but often use counters or
walls for support to get on and off the toilet. All people we surveyed agreed that the higher a seat
it, the easier it is to sit or stand.
There were also common difficulties each person experienced while using the walkers. The most
common difficulty was getting through narrow passages or around tight corners even in their
own home. The people we interviewed also had trouble with single steps such as curbs and
sliding the walker along different surfaces such as carpet, snowy sidewalks, or grass.
We asked the people we interviewed to prioritize certain features of the walker. Answers
amongst the people were consistent: the walkers need to be very sturdy, lightweight, able to fold
well, and need to be able to maneuver through narrow passages and around obstacles. Some
features with lower priorities were having a seat, storage compartment, trays or cup holders, and
an aesthetically pleasing appearance. Further survey results can be found in Chapter 3.
Additionally, there may also be a market for this product in hospitals as well. For patients in
hospitals of all ages suffering from different problems or injuries, this walker could help with
bathroom assistance. According to Jackie Augustine, a nursing student at U of M, typically bed-
ridden patients will use a bed-pan slid underneath them on the bed, a bedside urinal, or for

10. 10
patients who are able to sit up but not move well, a bedside toilet is very commonly used as
shown in Figure 1.
Figure 1: A bedside toilet commonly used in hospitals for immobile patients
If successfully implemented, we believe our product could combine the bedside toilet, a walker,
and a wheelchair into one product, which could potentially save the hospitals money on
healthcare products. Further discussion of the bedside will continue in Chapter 3.

11. 11
Section 1.2 – Project Description
The goal of this project was to create a walker designed for someone transitioning between a
walker and wheelchair. In hopes of one day making a product on the market, we decided to
modify an already existing walker by adding more features but maintaining features of the
original model. These features include being structurally integral, having strong brakes, large
wheels on each leg, being able to fold, having a seat and backrest, being adjustable for different
users, and most importantly, being safe.
To improve bathroom safety, we decided to incorporate a toilet seat onto the walker so the
walker could be pushed over a toilet for the user to do their business. The toilet seat would be
hidden below a cover seat, which would still have a backrest like the original walker. The
advantages to having a built-in toilet seat are that the seat would be raised making it easier to sit
and stand for an elderly person. Also, the user could sit on the built-in toilet seat in a comfortable
area perhaps by the sink or door, and then be pushed over the toilet. Lastly, a built-in toilet seat is
much more sanitary than public toilet seats. On the other hand, the disadvantages of the toilet
seat are that it would add extra weight to the walker, being visible in public could humiliate the
user, and the frame of the walker would have to be modified because one of the front cross bars
would prevent the walker from rolling over the toilet. Therefore, we had to keep this seat
lightweight, well-hidden, and had to preserve the structural integrity of the walker frame while
removing the crossbar.
The second major addition to the walker is being able to convert to a stroller or wheelchair so a
second person could push the user for longer distances by adding an extra set of handles in the

12. 12
front and foot pegs for the user to rest his or her feet. The advantages of converting the walker to
a stroller include expanding the range a handicapped person could travel while making it safer
and easier to travel long distances. The disadvantages include adding more weight to the walker,
the foot pegs could interfere with walking, and the extra handles would increase the overall
dimensions of the walker.
We foresee a future in this project so another goal of the walker is to be able to mass-produce it
someday. Therefore we want to keep as much of the original walker as possible making a limited
number of changes or additions. Also, the extra parts we make have to be simple and cheap to
make on a large scale in order to make the walker economic.

13. 13
Chapter 2 – Design of the Walkers
This project began in Winter 2011 when I teamed up with Corwin Stout, Kyle Happy, and Jonah
Shapiro to create an alpha design to meet the project requirements. The alpha design could be
successfully used in the restroom and also as a stroller. However, there were small issues with
the design that needed improvement so in Fall 2012, I teamed up with Alex Pham, Josh Getz,
David Wobith, and Phillip Davis to create a second prototype that satisfied all requirements and
improved upon the first design. In this Chapter, I will discuss the engineering specifications and
functional requirements of the walker. Then I will briefly describe the alpha design and then give
a detailed description of the beta design.
Section 2.1 – Functional Requirements and Engineering Specifications
For this project, we would be modifying an existing 4-wheeled rolling walker. There are
several companies and many models of 4-wheeled rolling walkers but they all have similar
features and capabilities. While modifying the walkers, we needed to add new features while
maintaining all the original characteristics. A standard 4-wheeled walker is very sturdy and can
support a person’s weight. The walkers have four wheels with pivoting front wheels and the rear
wheels have brakes. The handles used for walking are adjustable for people of different heights
and contain the brake handles also. These walkers also contain a seat with a backrest and usually
a basket for storage located beneath or near the seat. The walkers are made of aluminum to be
structurally sound and are also lightweight. Lastly, the walkers are capable of folding up for
storage or travelling in the car. After modifications, our designs need to meet these functional
requirements also.

14. 14
After modifications, the walkers must follow the same specifications as the original
models. The prototypes must hold up to 400 lbs. The Mini-Mack walker, which we used as a
platform for the second prototype, has a width of 23”, length of 29”, and a height of 30-38” with
the adjustable handles. With the built in toilet seat, the walker must fit over a toilet. We
measured 12 different toilets including Dick Sarns’s toilet, toilets from several houses, and
public toilets and found no toilets that exceed 17” in height or 14” in width. Therefore, the
lowest point on our seat needed to be 18” above the ground to clear the toilet seat and the legs
needed to be greater than 14” apart measured from the inside.
This product has potential to be placed on the market. While this thesis paper primarily
focuses on the walker itself, the designs had to be as economical as possible by limiting the
number of modifications, reducing the number of additional parts, and designing simple parts
that could more easily be mass produced. Also, if possible, we made new parts from the same
materials as the existing walker. For example, the additional handles of the beta design and the
frame of the walker are both made from 6061 aluminum tubing with a 1” diameter.
Lastly, this product must be as safe as possible. There could not be any sharp corners and
the number of pinch points had to be minimized. From a top view, no significant weight could be
applied outside the four contact points between the wheels and the ground to prevent the walker
from tipping over while in use. Common areas of applying weight include the handlebars, the
extra handle bars, the seat, and the foot pegs. We assumed the Mini-Mack walker was safe and
structurally sound, which is another reason for reducing the number of modifications on the
walker.

15. 15
Section 2.2 – Alpha Design
In Winter 2011, Corwin Stout, Kyle Happy, Jonah Shapiro, and I designed and manufactured a
walker from the Guarding Onvoy 480 of Figure 2.
Figure 2 (left): Guardian Onvoy 480 before modifications
Figure 3 (right): Guardian Onvoy 480 after modifications
The Guardian Onvoy 480 is walker with four large wheels, hand brakes, a seat with storage
underneath, a backrest, and is capable of folding by raising the seat. The alpha-prototype can be
seen in Figure 3 and a description of the changes follows.

16. 16
To add a hidden toilet seat, we removed the original seat of the walker as well as the storage
underneath. We purchased a wooden toilet seat and cut and trimmed it down from an ‘O’ shape
to a ‘U’ shape. We could not simply install the toilet seat with the original seat because the
original seat would not cover the toilet seat. Therefore we decided to design and fabricate our
own cover seat made from a composite wood covered with thin layers of foam and a fine
leathery vinyl on the outside. The cover seat was connected directly to the toilet seat using a
special hinge we designed and fabricated. The toilet seat was connected to the frame using a
separate hinge system standard with the Guardian Onvoy. With a larger cover seat, the backrest
interfered with the cover seat rising up for bathroom use. To fix this, we elevated the backrest.
The cover seat could now rotate upwards but there was nothing to stop it so we installed a belt
between the backrest and the frame’s cross bar to catch the seat as it fell backwards. We also had
to remove the front cross bar so the walker could fit over a toilet. We validated this decision by
applying a load of 400 lbs. to the modified walker without failure. To use this walker as a
stroller, we simply added custom-made steel foot pegs that could fold up and down by a 90
degree rotation. With the elevated backrest, the helper could either push from the front or back as
seen in Figures 4 and 5.
Figure 4: Pushing from Behind the User Figure 5: Pushing in Front of the User

17. 17
Section 2.3 – Alpha Design Feedback
When we finished the alpha prototype, we tested it ourselves and also interviewed more senior
citizens to get their opinion. In general the added toilet seat and stroller capabilities were
beneficial additions but small modifications needed to be made. First, while the toilet seat was a
‘U’ shape to allow the user to reach their bottom, the back cross bar that seat is resting on
prevented hand access. Also, the backrest was much too high for many users, especially because
many elderly people tend to hunch over. Next, while strap did prevent the seat from tilting, we
needed to limit the range of motion in the hinge, not with an extra strap, which looks very
unprofessional. The alpha prototype is able to fold but the pull-up bar often fell below the walker
as seen in Figure 3. To fix this, the pull-up bar could be directly attached to the toilet seat so
when the toilet seat is raised, the walker will fold up.
Section 2.4 – Beta Design
In Fall 2012, I teamed up with an ME 450 team with Alex Pham, Phillip Davis, Joshua Getz, and
David Wobith to create the second prototype. Instead of the Guardian Onvoy 480, we decided to
use the Nova Mini-Mack walker as a platform because it is smaller for people like Norma, and
has much better online reviews than the Guardian Onvoy. The goals of the project were the same
to install a hidden toilet seat and convert it to a stroller. We would also make improvements
based on the feedback of the alpha design. Figures 6, 7, 8, and 9 show the before and after views
of the Mini-Mack walker. This section gives a brief overview of the changes. Please refer to
Appendix B for details on manufacturing.

18. 18
Figure 6 (upper-left): The Mini-Mack walker before modifications
Figure 7 (upper-right): The beta design can be used as a chair or stroller
Figure 8 (lower-left): The beta design has a built-in toilet seat to be rolled over a toilet
Figure 9 (lower-right): The backrest can fold down for increased visibility while walking

19. 19
Section 2.4.1 – Framework: The walker’s frame has several modifications to accommodate the
new seat assembly. In order to slide over the toilet, the front-most cross bar was removed. Then
we welded in small triangular supports on the upper-front cross bar for additional frame support
(see Figure 15). Based on the feedback from the alpha design, the rear cross bar had to be
modified to prevent the bar from interfering with the user’s hand to wipe his or her rear end. The
new crossbar directly takes the place of the old one (Figure 10) and allows hand access and also
acts as guidance to the toilet: when the crossbar hits the toilet, the walker is in the correct
position above the toilet. We also removed the backrest of the Mini-Mack to make way for a new
one.
Figure 10: The rear-cross bar directly takes the place of the original crossbar but its
unique shape allows the user to wipe properly and serves as a guide above the toilet
Section 2.4.2 – Seat Assembly
There are several components of the seat assembly and each component has its own purpose.
First, there is a toilet seat that allows the user to sit on the walker before rolling over the toilet.
When the toilet seat is raised, the walker will fold up similar to the original Mini-Mack walker.

20. 20
On top of the toilet seat lays the cover seat, which must conceal the toilet seat. Lastly, there is the
backrest that should provide better lumbar support than the single bent tube standard with the
Mini-Mack. The toilet seat, cover seat, and backrest must all be comfortable, lightweight, and
able to fold up and down approximately 100 degrees from the horizontal plane. To allow all
three to fold independently, we created a special hinge, which was welded to the front crossbar.
We used all the brackets that came with the Mini-Mack seat. The first set of brackets act as a
hinge, the second set attach to the fold-up bar so the walker folds up when the seat is raised, and
the last set of brackets help lock the seat in place by snap-fitting to the rear crossbar.
Figure 11: The toilet seat has three sets of brackets. At the top of the picture, the pivoting
brackets act as a hinge. Next the pull-up brackets attach to the pull-up bar folding the
walker when the seat is raised. The last set of brackets helps attach the seat to the crossbar.
In the alpha prototype, we designed and built our own cover seat with wood, layers of
foam, and a fine leathery vinyl. For the beta design, we decided to get a simple office chair seen
in Figure 13, cut it apart, and modify it for the walker to save time and money. The cover seat

21. 21
was made from the flat part of the chair while the backrest was made from the chair’s backrest,
but the two were separated with a hacksaw and attached separately to allow independent rotation
depending on the walker’s use.
Figure 12: The office chair used for the walker. The backrest and seat are attached to the
steel frame with screws. This also shows the cut areas with the hacksaw
Based on the feedback from the alpha prototype, we learned the hinge was a vital part to the
walker. The hinge allows the toilet seat, cover seat, and backrest to rotate independently and
must prevent all three from rotating more than 100 degrees from the horizontal.

22. 22
Figure 13: The hinge allows the toilet seat, cover-seat, and backrest to rotate independently
and prevents the backrest from rotating 100 degrees beyond the horizontal
Figure 14: The hinge configuration. The rounded bottom is welded to the front crossbar
Figure 15: A front view of the actual hinge. A triangular piece is welded for extra support

23. 23
Section 2.4.3 - Foot pegs and extra handles: The last task is to convert the walker to an
optional stroller, which requires a set of foot pegs for the user and a set of handles in the front of
the walker so a second person can push the user around. For the foot pegs, we decided to use
existing foot pegs from a wheelchair for several reasons. First, it’s easier to implement into the
design, these are common foot pegs so they are economical, and lastly these will be safe.
Figure 16: CAD model of the foot peg and the bracket
Figure 17: Actual foot peg and bracket is located 0.5” from the top of the wheel bracket
The last addition to the walker was the additional handles, which allowed the helper to push the
walker user. While in stroller mode, everything is reversed and the user is facing backwards.
Based on our surveys, people preferred being pushed forward so we installed the extra handles in
the front of the walker, which is the rear of the stroller. They were installed in the same brackets
used for the standard backrest.

24. 24
Chapter 3 - Validation
Upon completion, we validated the walker by applying weight and using finite element analysis
to demonstrate its structural integrity. Above all other aspects of the walker, it must be safe to
use and cannot fail. We assumed standard parts of the Mini-Mack were tested, validated, and
safe to use such as the wheels, handles, and brakes. Any parts added or modifications made had
to be validated.
Section 3.1 – Framework: We validated the modifications to the frame both with finite element
analysis with Solidworks and also by applying a 400 lbs. force to the actual walker prototype. As
shown in Figures 23, 24, 25, the frame can support the designated force.
Figure 18 (left): Using finite element analysis in SolidWorks, the bracket can help support
the 400 lbs. force without failure
Figure 19 (right): The rear-cross bar can take a load of 400 lbs. without failure. The red is
only displacement

25. 25
Figure 20 (lower-left): The walker can support 400 lbs. static load on the seat
Figure 21 (lower-right): Each handle can support 100 lbs. without failure

26. 26
Figure 22 (upper-left): The backrest and hinge can support 100 lbs.
Figure 23 (upper-right): The handles can support 133 lbs. at a tilted angle
Figure 24 (lower-left): The handles can support 133 lbs. each while tilted forward
Figure 25 (lower-right): The handles can support 133 lbs. each while tilted backward
Section 3.2 – Handle Validation: To validate the strength of the extra handles, we applied a
force of 100 lbs. to each handle as shown in Figure 25. A healthy person would only use the
extra handles, not the handicapped person so there is a smaller chance of accidents occurring
with the extra handles. As mentioned earlier in this paper, if a part of the Mini-Mack walker was
unmodified, we assumed it was validated and safe. Although we did not modify the standard

27. 27
handles, we decided to add weight to the handles because the frame was modified. As seen in
Figures 28, 29, and 30, the handles can support 133 lbs. each at various angles.
Section 3.3 – Foot peg validation: The walker is rated for a maximum of 400 lbs. While the
foot pegs should only be used while sitting, we anticipate someone to stand on the pegs.
Therefore, the foot pegs should be able to take 200 lbs. each. To validate the foot pegs, we
applied a 200 lbs. force to each foot peg one at a time and simultaneously without failure. This
weight did not cause the walker to flip over either, which was another concern.

28. 28
Chapter 4 -Feedback and Improvements
Throughout the course of this project, approximately 50 walker users have been interviewed. In
the Winter 2011, when the project began, we interviewed 16 users to understand the most
important features of the walker. Upon completion of the alpha prototype, we conducted a
second survey with about 10 people and testers used the toilet feature. The feedback has been
briefly discussed in section 2.2. After building the second prototype, we interviewed 25 more
elderly people and one nurse from the University of Michigan hospital. Based on the feedback, I
have suggestions to improve this product.
Section 4.1 – Survey Questions
We conducted several surveys throughout the various stages of the project. We interviewed
before and after each of the two prototypes were built. After the beta prototype was complete, we
did a much more thorough survey with 25 participants. I made the questions for the final survey
and had help from Grant Benson, a survey director at the University of Michigan, who helped
format and make the questions. Due to poor vision and writing capabilities of the participants,
we read the survey questions to them and wrote down their responses. Here are the questions of
the final survey in order from front to finish exactly as they appeared in the survey (answer
boxes are excluded):
A. Section A: Patient Overview
1. What is your gender?
2. What is your height?

29. 29
3. On a scale from 1 to 10, where 1 indicates being unable to move without the
walker, and 10 indicates being able to walk freely without the walker, how mobile
are you?
4. Now thinking about your mobility with your regular walker. On a scale from 1 to
10, where 1 indicates being unable to move with a walker and 10 indicates being
able to move freely with a walker, how mobile are you with your regular walker?
5. Do you require human assistance to stand up?
6. Do you require human assistance to use the restroom?
7. We are particularly interested in bathroom safety. Please tell us what difficulties
you have in the restroom.
B. Section B: Current Device
1. How many wheels does your walker have?
2. Does your current walker have a backrest?
3. Does your current walker have footrests?
4. Does your current walker have storage?
5. Can your current walker be folded for travelling or storage purposes?
6. Can your current walker be used as a stroller?
7. Please comment on the features of your walker you enjoy the most.
8. Please comment on the struggles you have with your walker.
C. Section C: Prototype Walker
1. Do you agree the prototype is more attractive and aesthetically pleasing than your
old walker. Please comment on the appearance

30. 30
2. Do you agree the prototype is more comfortable than your old walker. Please
comment on the seat and backrest of the prototype.
3. Do you feel safer using the prototype than with your walker. Please comment on
the hazards you foresee with the prototype.
4. Do you agree the toilet seat is an important addition to the walker?
5. Is it easier to stand from the walker’s toilet seat than a public toilet seat?
6. Would you rather use the walker’s toilet seat than a public toilet seat?
7. Please comment on the walker’s toilet seat.
8. Do the foot pegs interfere while walking?
9. Are the foot pegs comfortable?
10. Are the foot pegs easy to employ and deploy?
11. Please comment on the walker’s foot pegs.
12. Do the hooks provide adequate storage?
13. Would you rather use the new prototype than your old walker?
14. Please make any final comments on the prototype.
Section 4.2 - Elderly Feedback
This section will describe the answers to the survey questions in Section 4.1. The group
was split evenly between male and female. The average male was approximately 5’9” and
the average female was approximately 5’5. I use the word approximately because many
users hunched over a lot and not everyone knew their own height due to shrinking, poor
memory, or they were sensitive about their height, weight, and age. For that reason, we did
not ask the age but we think most were in their seventies and eighties. Every person we

31. 31
interviewed used a rolling walker and most only had one. Each person also relied heavily
on the walker but did not need human assistance to stand, walk, or use the restroom.
In general, every elderly person relies on the walker for different reasons: some have poor
balance, some are too weak, and some are recovering from an injury. Additionally, some
rely on the walker more than others: some use it only for longer trips and some can’t take
two steps without it. However all of the people who use the walker do not require
assistance from other people to get from point A to point B and really don’t like being
helped, unlike a wheelchair. Most of the surveys have had pretty similar results and while
more surveys could certainly help, I have a good idea what should be done to improve the
walker. I’ll describe each aspect of the walker from most important to least important and
this includes standard walker sections like the brakes and wheels, and also things we
added on like the toilet seat and the foot pegs. I’ll also say what we can do to improve it.
The most important aspect of the walker is stability by far. If they don’t think they’re
holding onto something sturdy, then they wouldn’t hold onto it. Our prototype passes this
test with very positive feedback. The additional weight from the seat and footrests actually
makes the walker feel more stable.
The second most important features of the walker are the wheels and the brakes. 100% of
the people commented that larger wheels are better and the brakes need to be very strong.
Smaller wheels can often get caught on carpets, cracks in the sidewalks, etc. The brakes are
an extremely important safety feature. One person said he fell over once because his brake

32. 32
lock didn’t work properly and he put his weight on the walker, which rolled out from
underneath him. Everyone agreed our prototype had extremely good wheels and brakes,
which came with the Mini-Mack.
Next, the general mobility of the walker is also very important. While only some use the
seat and storage features of the walker, all the users have the walker for moving around.
The prototype is good for getting around and the foot pegs don’t get in the way of anyone.
The prototype is also heavy which most agree gives an extra feeling of stability. On the
negative side, occasionally they will encounter a single step or a curb. Most people said
they could handle one step going up or down with their personal walker but many thought
they would struggle getting up a step with our heavy prototype. The prototype does need
to shed some weight.
With the mobility aspect, there’s also the folding feature. In the most of the surveys, people
explained the importance of folding, especially when it comes to putting it in a car. While
the prototype is capable of folding, it’s much more difficult to put in a car because it’s
heavier, the extra handles make it take more space, and it doesn’t like to stay in the folded
position. Whenever I put it in my car for transportation, I had to remove the original
handles of the Mini-Mack.
The size and adjustability of the walker is important so it can work for people of different
sizes. The Mini-Mack is meant for someone smaller, like Norma, but the average person is
too tall for the Mini-Mack. With the lower handles, people tend to hunch over more, which

33. 33
is bad posture. Also, just by looking at it, many of the testers said the seat was too low for
them. The lower the seat, the much more difficult it is to stand up, which is why the seat
needs to be higher. Also, the toilet seat barely clears a standard toilet, which defeats the
purpose of using the walker in the restroom.
Everything up to this point was consistent throughout the surveys, which is why I labeled
them as being more important. These were also features that most common walkers
emphasize. Now I’ll get into other features of the walker, which aren’t as important but
really separate walker A from walker B.
The seat is found every rolling walker we’ve seen but not everybody uses it. In general,
most people park their walker next to a chair or couch that they sit in. I asked why they
didn’t use the walker’s seat and there are two main reasons. First, the standard walker
seats aren’t that comfortable. Second, and more importantly, when they sit on a chair or
couch, they can use the walker to get into position and sit straight down onto the chair.
When they sit on the walker, they must turn around first, which can be tricky and
uncomfortable. Most everyone needs seats with arm rests for support to stand up, which
the walker does have with the standard handles. While the prototype walker is not
necessarily easier to sit on, it is much more comfortable than the average walker seat,
especially the backrest. There isn’t much we can do to improve turning around to sit on the
walker.

34. 34
There was a general consensus with the prototype’s seat and backrest. The seat is very
comfortable to sit on and feels very sturdy and reliable, which is good. On the other hand,
the seat is a bit bulky; both folded up and folded down, especially because the Mini-Mack is
meant for a small person. The seat on the walker is just an office chair cut apart and
modified for the walker. If this were to go into production, we could keep the hinge
mechanism but reduce the size of the seat by making it flatter and thinner.
The toilet seat is always an eye opener, which has had mixed reviews. Nobody has tested
the toilet seat the way it was intended for but we have had fully clothed people sit on it see
if it was comfortable. Everyone who tried the seat agrees it is comfortable and you can sit
fully upright without the cover seat digging into the back. The seat does need to be raised
as mentioned before otherwise it is defeating its own purpose. Not one of the people we
interviewed was to the point of needing such a device but most agreed it could be useful for
certain people. It could be used in a hospital in place of a bedpan.
Additionally, the foot pegs and extra handles were by far the most controversial. I
explained to the testers that our walker is meant for someone who is transitioning from a
walker to a wheelchair. The majority said they’d rather go straight from the walker to the
wheelchair as one is independent and the other is dependent. Some of the people really
liked the idea though. The foot pegs are currently a bit uncomfortable because the walker is
so tiny. Extending the legs by a few inches would improve this. The foot pegs also add a lot
of weight, which people did not like. The foot pegs do not get in the way while walking,
which is very good. From the person pushing, the extra handles feel very sturdy and

35. 35
comfortable to hold onto. The shape is also aesthetically pleasing as the curves compliment
the curves of the original Mini-Mack walker.
Lastly, there are some sanitary concerns. While the personal toilet seat is likely to be
cleaner than a public toilet seat, some users say they don’t like the idea because the walker
would become contaminated. Also folding the walker up requires the user to touch the
toilet seat, which is unfavorable. A simple solution is to include a small pouch on the
bottom of the cover seat in the middle where individually wrapped wipes can be placed.
This way, the toilet seat can easily be cleaned after use or before folding up the walker.
Section 4.3 - Nursing Feedback
The walker project was initially meant for use at home, but we realized there is potential for
hospital use. I interviewed my friend, Jackie Augenstein, who gave some very valuable input. At
hospitals, every patient is different, but there are a large number who are bed-ridden but able to
sit up slightly on their own. These people will often use a bedside toilet as seen in Figure 1.
Hospitals also use walkers and wheelchairs regularly. Quoting Jackie, “It’s great because it’s
cost efficient because everything we made already exists and we combine everything
together. They would get a lot of use out of it as well. Good for hospitals and at home. Good
for patients in and out of hospitals. Thinks a lot of people could use it for multi-purposes.
Combining several into one makes it better.” In other words, our prototype combines a
walker, a wheelchair, and a bedside toilet all into one, which could save the hospitals a lot
of money. While using the bedside toilet, patients are often uncomfortable because their
only privacy comes from a thin curtain that wraps around the bed, while other people are
still in the room. With the new invention, the user could sit on the toilet seat the same way

36. 36
they did with the bedside toilet, and then be wheeled to the bathroom as an option over the
bedpan. Jackie thinks very highly of the prototype and only suggests we include a way to
attach a bedpan or bowl underneath the walker [6].
Section 4.4 - Future Improvements
After building the first prototype, we tested it and made improvements based on the
feedback. Now that the second prototype is complete as well as testing, I have suggestions
for how it can be improved. With graduation approaching, I will not be able to make the
improvements myself.
The first of many improvements is to make the seat slightly thinner and less bulky. The seat
was taken from an office chair and has a slight curve to it, which prevents the seats from
stacking nicely while folded down. To improve this, we would have to design our own seat
and backrest of the same width and height but a thinner and flatter thickness. Also, to
conceal the toilet seat even better, the new cover seat could have a slight lip around the
edge to hide the toilet seat. If this modification is made, then the size of the hinge could be
slightly reduced too. This could slightly reduce the weight as well.
Being able to convert to a stroller had mixed reviews. While it’s a nice feature, it may only
be used a couple times a month or year depending on the person. Otherwise, the user has
to lug around the extra weight and equipment. The solution is simple: make the extra
handles and footrests an accessory item that can easily be installed or removed by hand. A
knob similar to the one used to adjust the original handles could be used, or perhaps a snap

37. 37
fit feature or wing nuts. This could also help reduce the weight, which is a big problem. The
walker would only be weighed down when it is used as a stroller, but this is acceptable
because ideally a healthy person would be pushing the walker and would not have trouble
with the extra weight.
The Mini-Mack walker is designed for a smaller person in the 5’0” range and is therefore
much smaller than the average person with a lower seat. A common complaint of our
prototype is the toilet seat and cover seat are both too low, which defeats the purpose of
having a higher seat for easy standing. The toilet seat barely clears a standard toilet. There
are two solutions to this problem. First on the current prototype, extend each of the 4 legs
near the wheels to elevate both seats 2 to 3 inches. Another solution is to make a third
prototype on a larger model walker for a taller platform. All 4-wheeled rolling walkers have
a very similar structure so converting to a larger platform, much like the alpha design,
would not be a difficult task.
Lastly, the walker was originally designed to be rolled over a toilet. To make this walker
suitable for hospital use based on the feedback from Jackie Augustine, we should include a
latch or hook system located beneath the two cross bars that support the seat that could
hold a bowl or bedpan directly below the walker. The bowl or bedpan should easily be able
to slide in and out from under the walker. This way the nurse could prepare the walker
next to the bed with the patient, help the patient onto the walker, let the patient do his or
her business, and then remove and either dispose or clean the bedpan. Jackie strongly

38. 38
believes improving a design that already exists and combining the walker, bedside toilet,
and wheelchair into one object could save the hospital a lot of money.

39. 39
Chapter 4: Conclusions
The goal of this project was to design and fabricate a walker that could improve
bathroom safety and could also be used as a stroller. We have successfully designed and built
two different prototypes, which both include a built-in toilet seat hidden by a cover seat so the
walker can be rolled over the toilet providing a taller, safer, and more sanitary toilet seat to sit
on. Additionally, both walkers included a set of foot pegs and extra handles to be converted to
stroller. We validated the 400 lbs. maximum weight capacity by applying weight to the frame of
the walker without failure.
Initially, this project was intended for Norma Sarns, the wife of our sponsor, Dick Sarns.
We soon realized this walker could be used on a larger scale and that there may be a market for
this product. With that being said, we designed the walker to be economical using already
existing parts and adding new parts with simple, common designs. We also interviewed many
senior citizens to get opinions on the walker and so we could make improvements based on the
feedback. We also learned there could be a large market for this product in hospitals because our
walker combines wheelchairs, walkers, and bed side toilets into one product, which could save
hospitals thousands of dollars on health-care products.
There remains work to be done on this project. First the design has a few small
modifications to reach out to a larger group of people. Second, there needs to be a market
analysis so we can make a better prediction of the market size and economic values to see if this
product can be profitable or not in the future.

40. 40
References:
[1] Disability Walkers and Zimmer frames for disabled and elderly. (2010, February 6).
Retrieved January 27, 2011, from Disablility Walkers.
[2] seniorjournal.com. (n.d.). Retrieved 1 26, 2011, from Falls Have Become the Leading Cause
of Injury Deaths for Senior Citizen .
[3] L. Gillespie, H. H. (2009). Prevention of falls and fall-related injuries in older people.
Retrieved from injuryprevention: http://injuryprevention.bmj.com/content/15/5/354.full
[4] Some Amazing Bathrooms Statistics on Elderly Injuries. (n.d.). Retrieved from
Showerchair.biz.
[5] Sarns, Dick and Norma (2011, 1 14). NuStep Owner.
[6] Augenstein, Jackie. (2013, 3 14). University of Michigan Nursing Student. (C. Moelmann,
Interviewer)

41. 41
Appendix A: Bill of Materials
Part Qty Material Supplier Cost Part #
Foot Plate 2 -- 4MDMedical 46.05 WCA806900
http://www.4mdmedical.com/aluminum-wheelchair-footplate.html
Toilet Seat 1 Wood Bemis 15 TC50TTA
http://www.bemisseats.com/catalog/wholesale/model/7BTC50TTA/
Seat/Backrest 1 --
Marco Group
Inc.
50 600 Series
http://www.marcogroupinc.com/commercialstackingchairs.html
Nylon Bushings 4 -- McMaster Carr 3.01 6389K113
Hinge Wall 4 1/4" 6061 Al Plate McMaster Carr 14.05 8975K434
Hinge Pin 6 1/4" 6061 Al Rod McMaster Carr 3.6 6750K131
Backrest Stop 2 3/8" 6061 Al Rod McMaster Carr 5.94 6750K151
Frame Support
Brackets
2 1/4" 6061 Al Plate McMaster Carr 22.8 6023K281
Flange 2 -- McMaster Carr 70.4 9578T710
Handles 2
1"OD, 0.5" ID Al
Rod
McMaster Carr 20.24 9056K282
www.mcmastercarr.com
Mini-Mack Walker 1 -- Nova 200 --

42. 42
Appendix B: Manufacturing
Section B.1 – Framework: After removing the front-lower crossbar, we added a small
triangular piece between the front leg and front crossbar. The dimensions of the triangular piece
were 2.5” tall, 1.25” wide, and a thickness of 0.25”. See Figure 15.
The new crossbar is made from 0.75” 6061 aluminum tubing and was made with a tube bender to
specifications of Figure 11 below. Similarly the front crossbar that was removed, we removed
the rear crossbar with a hacksaw, smoothed down the cut-area with a file, and welded the new
crossbar in place in the same location as the original crossbar.
Figure B1: The rear crossbar drawing

43. 43
Section B.2 – Seat Assembly
We purchased a Bemis wooden toilet seat (Model #: TC50TTA) that is 15” long and 14” wide.
We cut the toilet seat from an ‘O’ shape to a ‘U’ shape using a bandsaw, a dremel, and
sandpaper. The standard seat of the Mini-Mack walker had two folding brackets that attach to the
folding mechanism so the walker will fold up when the seat is raised. There are also the pivoting
brackets, which act as a hinge connected to the front crossbar. Lastly, there is a set of two plastic
clips beneath the standard seat that connects the seat to the rear cross bar. All three sets of
brackets are screwed in place so we simply unscrewed each set to remove them. The added toilet
seat is a direct replacement for the standard Mini-Mack walker so we lined up and screwed the
brackets in the same locations on the toilet seat as on the original seat as seen if Figure 12. When
the brackets were correctly lined up, we lightly sandpapered the white toilet seat and spray-
painted everything black to help conceal the toilet seat. To install the toilet seat, we removed the
pivoting brackets and the folding brackets. Then we set the toilet seat on top of the cross bars,
and held the pull-up bars in the correct position while a second person screwed all four brackets
in place. As seen in Figure 12, the Mini-Mack came with two rubber stoppers to prevent the seat
from sliding back and forth. Those two stoppers also prevent the toilet seat from sliding back and
forth as well.
Both the seat and backrest are made with a piece of slightly curved wood covered in a
blue, soft fabric. The frame of the office chair was thin steel tubing with 0.625” diameter bent
and welded to make the shape of a chair. The seat and backrest were attached with two screws in
shown in Figure 12. Once removed from the chair, we put two 0.25” holes in the frame that
would be used to mount to the walker while allowing it to rotate using a special hinge we created
seen if Figure 13.

44. 44
The hinge allows the toilet seat, cover seat, and backrest to rotate independently. The
hinge must be rigid and help support the weight of someone sitting on the cover seat or leaning
on the backrest. Lastly, like all other components of the walker, it should be lightweight and well
confined to a small area. The hinge was made of two separate brackets that were each composed
of two walls made from 0.25” thick aluminum plating with three holes for 1.5” long 0.25”
aluminum rods to be placed through as seen in Figures 14 and 15. The wall was made with the
water jet and the 0.25” holes reamed according the drawing in Figure B2.
Figure B2: The drawing for the hinge bracket. Four of these pieces were fabricated.
We made six pins for the two hinges. The first pin supports the cover seat, the second pin
supports the backrest, and the third pin prevents the backrest from falling backwards. The pins

45. 45
were each made from a 0.25” aluminum rod cut 1.375” long. The cover seat and backrest pins
also were given two 0.19” diameter slots for e-clips located 0.85” from each other and 0.262”
from the ends of the rod to be symmetric.
We performed the following step-by-step operations to assemble the seats to the walker.
First we assembled both hinges by inserting the three pins into the holes of the hinge walls to
resemble Figure 15. Then we welded the top pin to secure the hinge together. On the front cross
bar, we then carefully welded the hinge walls to the walker frame so the hinge would rest at a 45-
degree angle to the horizontal as seen in Figure 14. The centers of the hinges were placed 18”
apart and equidistant from the sides of the walker to maintain symmetry. Once it cooled down,
removed the pins for the cover seat and backrest, held the cover seat and backrest in place, slid
the pins back in, and secured them with e-clips. Then we put the toilet seat back on with all sets
of brackets including the pull-up bar brackets.
Section B.3 - Foot pegs and extra handles: The foot peg will be attached to a special bracket
we design and fabricated, which would be attached to the rear leg of the walker with a bracket
we purchased from McMaster-Carr (#9578T710). Following the specifications of Figure 20, two
aluminum blocks for the foot support were cut down from a 1.5” plate of aluminum alloy 6061 to
the appropriate length and width using a band saw. Using a mill, four 0.26” holes four drilled in
the block. A 0.78” hole was drilled in the bottom of the block. Next, the foot support bar was
inserted to the hole in the bottom of the block and press fit using an arbor press. The aluminum
block was attached to the heavy-duty aluminum clamp-on framing fitting add-on flange using the
four machined 0.26” holes. The bolts on the flange were tightened on the frame of the walker
using a wrench.

46. 46
Figure B3: The drawing for the foot support block
The last addition to the walker was the additional handles. The handles were fabricated from 1”
6061 aluminum tubing (0.125” thickness). For each handle, we took a piece of this tubing 11”
long and bent it with a pipe bender according to the drawing in Figure B4.

47. 47
Figure B4 (left): The dimensions of the extra handles. Both holes are 0.25” diameter
Figure B5 (right): The extra handle on the walker
Once the pipe was bent, we put in two 0.25” holes placed 0.5” apart, which would be
used to attach to the walker. The walker has a bracket for the original backrest. With the backrest
removed, we decided to use the brackets to attach the handles. The bracket already had one 0.25”
hole so we added an extra one 0.5” away in the direction perpendicular to the leg of the walker.
We then bolted the handles in place. The ends of the handles we covered with a rubbery shrink-
wrap for hand comfort.