This document provides a summary of a team's design of an adjustable pediatric chair for mobility assessments. The chair was designed for patients aged 3-15 at a rehabilitation institute. The chair needs to be adjustable to accommodate patients of varying sizes and allow them to sit at 90 degree angles. The design consists of an H-shaped base with a telescoping spine that can be adjusted in height using a pin-locking system. The seat, backrest, and armrests are also adjustable to accommodate different patients. The team's design aims to meet requirements for adjustability, portability, safety, durability and build quality.

1.
DTC Section 15 Team 2 Final Report
Team:
Anant Gururaj, Aidan Sheehy,
Vickie Li, Rachel Connors
Instructors:
Emma DeCosta, John Bishop

2. Table of Contents 1
Introduction 2
Users and Requirements 3
Design Concept and Rationale 4
References 5
Appendices:
Appendix 1, Project Definition 12
Appendix 2, Bill of Materials 15
Appendix 3, Background Research Report 16
Appendix 4, User Observation Report 23
Appendix 5, User Testing Report 26
Appendix 6, Instructions for Use 31
Appendix 7, Instructions for Construction 33
Appendix 8: Executive Summary
1

3.
Introduction
The Timed Up and Go (TUG) test is a test performed by orthotists at the Rehabilitation
Institute of Chicago (RIC) to assess mobility among patients who have difficulty walking.
Patients must stand up and sit back down in a standardized position during the test. Depending
upon height, an individual’s joint angles will vary while sitting in the chair. This is a problem
particularly within the pediatric population because there is a great variation in height by age and
no single chair can accommodates the full range. Our team was asked to design and construct a
chair that could allow children of ages 3­15 to safely sit in a chair that allowed them to easily
maintain ninety degree angles about the elbows, hips, knees, and ankles. A fully adjustable chair
allows the RIC to have a standardized starting position, allowing them to collect better data and
more effectively determine whether or not their patient’s physical therapy is working.
Our solution to this problem was to create or adapt various mechanisms such that the
components of the chair could slide or insert and then lock using a pin or clamp. When all of the
mechanisms are combined, the result is a chair with adjustable seat height, seat depth, arm
height, and arm width such that those sitting in the chair can safely and comfortably obtain the
aforementioned ninety degree sitting angles.
This report explains the users, requirements, and specifications for the requested design,
followed by a detailed explanation of the design concepts and its rationale. We conclude with
recommendations for testing.
2

4.
Users and Requirements
Main Users of the Design:
Patients at the RIC​: The main users of this design are pediatric patients between the ages of 3 and
15 years old. Most of these patients are diagnosed with cerebral palsy and spina bifida, which
causes them to have reduced mobility in their limbs. Some of these users as a result have walking
aids such as crutches or walkers.
Orthotists at the RIC:​ Orthotists carry out the TUG tests on the patients. They are responsible for
adjusting the chair to the appropriate size for the patients via the adjustment mechanisms on the
chair. They also may have to provide assistance to the patient during the test should they need it.
Orthotists are also responsible for moving the chair from the examination room into the hallway
where the TUG test is carried out. This may be done up to 12 times per day.
We are specifically building for a range in sizes and weights for the patients age 3 to 15, and as a
result we researched the sitting height and weight within the 95th percentile for these ages, using
the 5% sitting height of 3 year olds for the minimum and 95% sitting height of 15 year olds for
the maximum. The minimum we aimed for was 10.24 in and the maximum was 18.11 in. We
also needed to have a maximum arm height of 29.92 in and a minimum of 17.32 in. Using
weight data, we knew the seat itself should be able to take at least 180 lbs of sitting force. We
also had to account for the front load on the seat if the patient is small enough that they sit
completely in front of the spine. Backtracking from our researching and finding what age reaches
this point, we found that this age should be around 5 years of age, and then found that the chair
should be able to accommodate at least 50 pounds of force.
Requirements:
Adjustability:​ The seat height, seat depth, seat width and arm height must be adjustable such that
any pediatric patient that uses it can achieve joint angles of 90º at their hips, knees and ankles.
3

5.
(Fig. 18 shows an user sitting with the various 90º angles required)
Portability:​ Due to little space at the RIC, the chair must either be collapsible to a degree such
that it can be stored in a closet or be able to function as a normal chair. The process of moving
the chair from an examination room to a hallway should be easy enough for an orthotist to carry
out without assistance. The hallway is approximately 4 feet wide and the doorway leading to the
hallway is approximately 2.5 feet wide.
Build and Durability​: The chair must be able to support the weight of any pediatric user. The
client specified a maximum weight of 180lb, so incorporating a safety factor of 2, the chair must
be able to support a weight of up to 180lb. Additionally, should there be any cushioning on the
chair, it must not hinder users from getting up naturally. The client also specified that the chair
be made with materials of gender neutral colours.
Safety:​ Given that the users have reduced mobility in their legs, it is plausible that they may not
have complete control of their motion when they are about to sit in the chair. Therefore, the chair
must be stable enough to prevent itself from tipping over should a user set themselves down in
an awkward manner. Additionally, there must be some space around the frame of the chair to
allow orthotists to be near the user if they need assistance.
4

6. Design Concept and Rationale
The final product is a chair with fully adjustable dimensions, including seat height, arm
height, arm distance, and seat depth. The chair begins with the base, which is constructed in an H
shape. The H shape of the seat base is chosen to ensure stability of the chair by ensuring support
on all four corners, while at the same time allowing the patient's legs and assistive devices to
move freely in front of the chair. Our interview with the physicians at RIC revealed that
portability of the devices is crucial, and the H shape also allows us to prevent the weight of
excess material on the base.
The spine of the chair attaches to the exact middle of the base, on the main branch of the
H shape. The spine consists of various sliding components put in place by a pin and lock system
that can best be described as a “telescoping mechanism”­ various parts of steel shaped into
identically sized square shaped tubes go about the center of the base (See Fig 1­3 at the bottom
for visuals). There are three of these, which fit inside of each other, facing vertically (these are
the adjusting spine pieces). The adjustable pieces can all slide about the vertical axis. To lock
these into place, there exists a hole that goes all the way through the piece at the top of the two
outside pieces and intermittently throughout the inside three that a pin can fit through and keep
them moving. To adjust the seat height, the user removes the pins, adjusts the telescoping
mechanism such that the top of the spine reaches the desired height from the ground, and then
the pins are put in place, keeping it at this height. The spine is attached to the middle of the base
to ensure stability and prevent the chair from tipping over when the patient is getting on or off
the seat. Four steel flanges are attached to both the spine and the base and seat using screws
wherever the spine is attached to the base and seat for extra stability. Multiple different
mechanisms were considered for the spine of the chair, and we arrived to the decision by
considering the ease of adjustment of each of these mechanisms, on of the most important feature
our design must have according to our user observation. Among the mechanisms considered, we
decided that a pin and lock system will be the easiest to adjust. The telescoping mechanism
normally used within a gas spring was adopted to lighten the weight of the spine and preserve the
5

7. center of balance of the seat. Aluminum was chosen as the material of this component of the
chair so the spine will add minimal weight to the chair while providing maximum strength.
(Figures 1,2,and 3 portray the compositions of the spine and the telescoping mechanism.)
(Figures 4 and 5 portray the pins used for the pin and lock system.)
6

8. (Fig 6, 7, and 8 show the process of adjusting the seat height: adjusting the height of the middle
tube and placing the first pin through, then placing the seat tube inside, adjusting to the proper
height, and placing the pin through.)
The seat itself is a plank of plywood that attaches to the very middle rectangular prism
component of the spine. The seat sits perpendicular to the spine, and if not fully extended
vertically, can rest upon the other components of the spine. The back is another large piece of
plywood that sits upon the seat such that they are perpendicular. In order to support the back, two
triangle shaped bases are attached to the back which provide balance for the back and make it
easier to slide about the seat. These triangles are attached at the edges of the back. The back can
slide across the seat easily in the direction facing the user. Two railings are attached to the sides
of the seat, and they sit on the edge of the seat so that they do not reach over the edge. The back
and back support fit snugly with it and can slide about it easily. Holes are drilled into the railing
and triangle support with 2 inch increment. When the user has settled upon an appropriate seat
depth, they slide pins into the holes which keep the back in place. During user observation, we
found out that the user prefers that the chair stay in one piece instead of consisting of multiple
removable components. So we decided on the sliding mechanism for the seat depth of the chair.
This will allow the user to easily adjust the largest component of the chair without lifting up or
taking apart the seat or back rest. The railing and clamp that holds these pieces in place prevents
the backrest from tilting away from the desired 90 degree angle.
(Fig. 9,10,11,12,13 show the seat and railings, the back, and the pins that keep the back in place.)
The arms are adjustable using both a pegboard mechanism (see Fig 9. for the pegboard)
and a pin and lock mechanism. Various square­shaped holes are drilled into the seat. All of these
7

9. holes have the same radius and distance apart from each other. The holes are constructed so that
they do not go all the way through the seat of the chair, but have the same depth as each other.
All of the holes are aligned in columns and rows, and the columns extend throughout the entire
surface of the seat.The actual arms are the same steel tubes used for the adjustment of the seat
height with planks of wood attached to them so the patient can rest on them. The adjustability
mechanism of the height of the arm is thus the same as that for the seat height. The arms can be
moved between all of the holes in the seat to best fit the size of the patient.
(Fig. 14,15, and 16 display the arm, the height raising mechanism, and how it fits into the seat.)
The dimensions of the base of the chair have an overall length of 22 inches and width of
24 in, such that the width is wider that the actual seat of the chair. The four skinny parts of each
H, or the parts that branch out from the middle, each have a width of 4 in and length of 6 in. The
thickness of the base is 1.5 in. The outermost component of the spine has height of 4 in with
width and length of 2 in, the middle tube of has height 8 in and width and height of 1.75 in, and
the innermost tube has height of 9 in with width and length of 1.5 in.​ ​The maximum height
obtained by this mechanism is 23.25 in from the base, while the minimum is 12 in.​ ​The holes
have a diameter of .43 in and will have (where relevant) a distance of .57 between the edges of
each hole. The pins are 2.5 inches in length, which is long enough to completely pass through all
components. The diameter of the pins will be .375 cm and fit snugly with the holes. We adopted
a pegboard adjusting mechanism for the armrests as it is the easiest way to adjust this component
8

10. in both width and depth. The holes of the pegboard are 1.5 in deep and have a width and length
of 1.9075 in. A telescoping and pin mechanism made of steel was adopted for height adjustment
to preserve space and to prevent adding too much weight to the chair.
The seat itself will be 22 in long and 22 in wide with a thickness of 1.5 in. The Back itself
is curved at the top and has a width of 23.375 in and maximum height point of 20.5 in. The
radius of hole: 3 in and Diameter: 6 in. The back is supported by two triangle shaped supports
that extend from its back side. The different measurements of the triangle as support are as
follows: The lowest plank has height: 1.55 in, length: .9 in, width:1.57 in; the middle support
which is horizontal and shaped like a trapezoid, has height: 1.56 in; below length: 4.7 in; upper
length: 4 in; angled length: 1.7 in; the plank attached to back, which faces vertically, has height:
11.6 in; width: 1.57 in; length: .77 in; and the longer, angled plank has top base length: 3.9 in,
bottom base length: 2.4 in, Hypotenuse length: 11.6 in, and angle: 60 degrees.
The railings have a height of 1.75 in, width of .75 in and a length of 22 in. For the
telescoping mechanisms on the arms, the outer layer has height: 9 in; width/length: 1.75
in, and the inner layer has height: 6 in; width/length: 1.5 in.The armrest is made of two layers of
plywood, the top which has a length of 9 in and the bottom length of 7 in, and both have a width
of 2 in and a thickness of 1.5 in. We decided on the dimensions of the chair by studying the
Nationwide age references for sitting height, leg length, and sitting height/height ratio, and their
diagnostic value for disproportionate growth disorders and targeting the 99th percentile of body
growth for children from the age of 3 to 15.
9

11. References
Alosa Foundation. ​Evaluate Gait and Mobility with the Timed Up­and­GO (TUG) Test​. Digital
image. ​Alosa Foundation​. N.p., Apr. 2014. Web. 9 Mar. 2016.
<http://www.alosafoundation.org/modules/falls­mobility/>.
“Amputee Mobility Predictor Tutorial­ Dayton Artificial Limb”.
https://www.youtube.com/watch?v=Y7V8nJraUYc​ Online Video Clip. ​Youtube. ​Youtube, 7
Nov. 2012. Web. 18 Jan 2016.
"Average Height and Weight Chart for Boys." ​Aaryoga.com​. Aaryoga Network, n.d. Web. 10
Mar. 2016.
<http://www.aarogya.com/family­health/childrens­health/average­height­a­weight­chart­for­boys
.html>.
"Children's Chair Little Scholar Kids Adjustable Chair." ​Www.reo­smart.com​. Web. 20 Jan.
2016. <http://www.reo­smart.com/PostureDesks_pink_fully_Kids_Adjustable_Chair_p/pc­318
­pk.html>.
"Faux Leather Tufted Swivel Adjustable Air Lift Dining Chair." ​Houzz​. Web. 20 Jan. 2016.
<​http://www.houzz.com/photos/21682685/Faux­Leather­Tufted­Swivel­Adjustable­Air­Lift­Dini
ng­Chair­Black­contemporary­dining­chairs​>.
Fredricks, A M, et al. “Nationwide age references for sitting height, leg length, and sitting
height/height ratio, and their diagnostic value for disproportionate growth disorders.” ​Archives of
Disease and Childhood. ​90 (2005): 807­812. Print.
10

12. Gailey RS, Roach KE, Applegate EB, et al. The amputee mobility predictor: an instrument to
assess determinants of the lower­limb amputee's ability to ambulate. Arch Phys Med Rehabil.
2002;83(5):613­627.
“Orthotists and Prosthetists”. Bureau of Labor Statistics, U.S. Department of Labor,
Occupational Outlook Handbook, 2016­17 Edition​, Orthotists and Prosthetists,
http://www.bls.gov/ooh/healthcare/orthotists­and­prosthetists.htm​. ​Web. January 18, 2016.
Wall, James C., PhD, Churan Bell, BS, and Jennifer Davis. "The Timed Get­up­and­go Test
Revisited: Measurement of the Component Tasks." ​VA Research & Development​. Journal of
Rehabilitation Research & Development, Jan.­Feb. 2000. Web. 18 Jan. 2016.
<​http://www.rehab.research.va.gov/jour/00/37/1/wall.htm​>.
11

13. Appendix 1.
Project Definition
Project Name​: Adjustable chair for TUG test standardisation for the RIC
Client​: Julianna Mandle, Rehabilitation Institute of Chicago (RIC)
Team Members​: Rachel Connors, Vickie Li, Aidan Sheehy, Anant Gururaj
Date​: February 28, 2016
Version​: Three
Mission Statement​: To Design an apparatus that can standardize the Timed Up and Go (TUG)
test for the pediatric population by making arm, hip, and leg angles 90​° while sitting comfortably
in a chair.
Problem Statement: ​The TUG test is an outcome measure test that measures the progress of
physical therapy. It requires the patient’s body to be positioned such that the​ ​arm, hip, and leg
angles 90​° while sitting with his or her back against the chair. Since the test is currently
conducted with the patient sitting on a standard sized chair, the test cannot be conducted on
pediatric patients whose body proportions do not allow them to be positioned in the current chair
correctly.
Project Deliverables​: A working prototype of the chair that can be used by the RIC and other
clinics to conduct TUG tests on paediatric patients with various disabilities.
Constraints​:
● Materials must not cost more than $100
● Must be built between January 6th, 2016 ­ March 4th 2016
Users/Stakeholders​:
● Pediatric patients at the RIC (the users)
12

14. ● Orthotists at the RIC (who now have more accurate data to assess the condition of the
user more accurately)
● Insurance agents (who now have access to better data when assessing insurance claims)
Requirement
Categories
Directives Requirements Specifications
Adjustability Must be fully
adjustable in seat
width, seat height,
seat depth, and
armrest height.
1. Seat width must
adjust between 0
and 19.7 in.
2. Seat height
should adjust
between 9.8 and
19.7 in with 2 in
increment.
3. Seat depth must
adjust between
5.9 and 19.7 in.
4. Armrest height
should adjust
between 3.9 and
11.8 cm.
1. Peg board of
width 23.6 in on
the seat.
2. Telescoping tubes
for pillar that
adjusts between
7.9 and 19.7 in.
3. Seat back that
slides along the
seat from 0 to 10
in.
4. Telescoping tubes
for armrest
support that
adjusts between
3.9 and 11.8 in.
Portability Must be able to be
stored and moved
around easily.
1. Can be moved by
one single
person.
2. When not in use,
should either fold
up or be used as a
normal chair.
1. Reduced chair
weight by
H­shaped base.
2. Seat pillar that is
able to withstand
an adult’s body
weight.
13

15. Stable and
secure
Must be stable and
secure when a child
gets on and off and
sits on it.
1. Should be able to
withstand up to
180 lbs of
weight.
2. Must not hinder
the use of
assistive devices
placed in front of
the chair.
3. Should not tip
over when the
child gets on or
off it­hold load of
at least 50
pounds.
1. Reinforced seat
that is consisted of
two layers of
plywood.
2. Metal tubes for
seat pillar that
withstands up to
180 lbs.
3. H­shaped base
that has a 8 in by
5.9 in space in the
front.
4. H­shaped base
that extends to all
four corners.
Ease of use Must be easily
adjusted and
sanitized.
1. Could be
adjusted by 2
people in 2
minutes.
2. Must be easily
sanitizable by
alcohol.
1. Pin and lock
system for height
adjustment.
2. Slider system for
seat depth
adjustment.
3. Wood used in
armrests, seat and
backrest that dries
quickly.
14

16. Appendix 2.
Bill of materials
Item Description Qty Vendor Part # Unit Cost
($)
Total Cost
($)
Telescoping
steel tube for
spine
Heavy Duty Steel
Bolt­Together
Framing, 2"
Square Tube, 4’
Long
1 McMaster 4931T125 25.98 25.98
Telescoping
steel tube for
spine
Heavy Duty Steel
Bolt­Together
Framing, 1­3/4"
Square Tube, 4’
Long
1 McMaster 4931T124 22.00 22.00
Telescoping
steel tube for
spine
Heavy Duty Steel
Bolt­Together
Framing, 1­1/2"
Square Tube, 4’
Long
1 McMaster 4913T123
20.69 20.69
Plywood 1/2" (15/32) x 4' x
8' Plywood
Sheathing
2 Menards 1231085 16.65 33.30
Zinc­Plated
Steel Pin with
Wire Lock
3/8” diameter, 2.5
inch length
4 McMaster­
Carr
98416A019 2.12 8.48
Low­Carbon
Steel
90 Degree Angle
3" X 4" Legs, 1/4"
Thickness, 1'
Length
1 McMaster­
Carr
9017K83 13.72 13.72
Wood Finish Polycrylic
Protective Finish
32 oz Ace 17.99 17.99
Total cost: $142.16
15

17. Appendix 3.
Background Research
At the beginning of the project, background research was conducted on terms and tests provided
to us by Ms. Julie Mandle from the Rehabilitation Institute of Chicago. These concepts are used
by physical therapists to evaluate outcome measures and the progress of their patients. The goal
of this project is to develop an apparatus that will help in standardizing data by recreating the
same arm, hip, and leg angles in chairs during various movement tests. Thus, most of our
research was directed towards understanding the tests as well as the population that would be
using the chair. We also needed to understand the overall process behind the machinery of
chairs. Specifically, we researched (1) orthotists and how they do their job, (2) the Amputee
Mobility Predictor and its applications, (3) the Timed Up and Go Test and its applications, and
(4) adjustable chairs.
Orthotists
Orthotists design and create medical supportive devices that custom fit patients in order to allow
them to live without their disability—the technology replaces whatever ability the patient has
lost. For example, if a patient was to have lost an arm, an orthotist could design a custom arm
that fits the patient and acts just like a real, functioning arm (Bureau of Labor Statistics).
16

18.
Fig 1. Patient’s arm has been replaced by technology designed by Orthotists
Source: Bureau of Labor and Statistics
<​http://www.bls.gov/ooh/healthcare/orthotists­and­prosthetists.htm#tab­2​>
Orthotists are involved in every part of the process—they determine what exactly the patient
needs. This is often through an interview process, taking measurements, and using impressions in
order to ensure accurate dimensions of the product or physician’s prescriptions. They then design
the product for the patients and even take additional steps such as showing patients how to use
and care for the orthotics as well as repairing the orthotics if they fail or get worn down (Bureau
of Labor Statistics).
Amputee Mobility Predictor
This is a test designed to calculate one’s mobile ability, and it is useful for determining whether
or not a patient’s physical therapy is working. In this test, the patient sits in a hard chair with
arms. The patient is allowed to use and any prosthesis they have. The patient carries out a variety
of tasks that test basic physical ability, such as sitting balance, sitting reach ability, chair to chair
17

19. transfer, arising from a chair, immediate standing balance, single limb standing balance, and
standing reach ability.
The test is based on a numerical scale calculated from how subjectively well the patients perform
the aforementioned tasks. For example, if the patient is able to easily switch from sitting in one
chair to another, the patient receives a score of “2” for this test. If the patient requires some
assistance in switching chairs, they are assigned a score of “1”. If they are completely unable to
perform the task regardless of help provided, then they are assigned a score of “0” (Gailey RS).
At the end of the testing, each individual score is added up to create a final calculation, which
can be useful for measuring improvement during physical therapy.
Fig 2. Depicts a physical therapist and a patient using the Amputee Mobility Predictor to
determine the patient’s single limb standing ability.
Source: Amputee Mobility Predictor Tutorial
<​https://www.youtube.com/watch?v=Y7V8nJraUYc​>
The product we will be designing comes into play with the sitting part of the test. Although the
chair is standard for the adult, there is a very wide range of heights from toddlers through
teenagers and having a chair that can create the same body angles requires an adjustable chair.
18

20.
Timed Up and Go
The Timed Up and Go Test is another test of physical capability. Unlike the Amputee Mobility
Predictor, the Timed Up and Go measures ability in terms of time taken to complete the task
instead of qualitatively observing and then assigning a numerical basis. At its essence, the test
involves standing up from sitting down in a chair, walking a standardized distance, turning
around, walking back to the chair and sitting back down in the original position. Specifically, the
test involves a standard armchair (46 cm seat height with arm height of 67 cm from the ground)
in which the patient sits with ninety degree joint angles at the hips, arms, and knees. Their back
should be against the chair and their arms on the arm rests. During the walking, the patient is
allowed to use any device they use for walking normally. Once the patient reaches the 3m
distance that is established in the form of a visible line, they turn around and sit back down. To
end the test, the patient must sit down with their back against the seat (Wall, James C., PhD,
Churan Bell, BS, and Jennifer Davis).
Fig 3. Contains a diagram of the Timed Up and Go test.
Source: Wall, James PhD <http://www.rehab.research.va.gov/jour/00/37/1/wall.htm>
The need for this chair is fundamentally the same for the AMP test—standardizing body position
for a movement test.
19

21. Existing Adjustable Chairs
As part of our research, we also looked into existing adjustable chairs. We discovered that there
were many different solutions to changing features such as seat height.
Fig 4: A “Fully Adjustable” Children’s chair
Source: Reo­Smart
<​http://www.reo­smart.com/PostureDesks_pink_fully_Kids_Adjustable_Chair_p/pc­318­pk.htm
>
This Reo­Smart chair’s seat and back are adjustable through placing a key through aligning holes
in the spine of the chair. In contrast, the following chair is adjustable through the use of pressure
in the chamber of the rod below the chair.
20

22.
Fig 5: ​Swivel Adjustable Air Lift Dining Chair
Source: Houzz <http://www.houzz.com/photos/21682685>
21

23. References
“Amputee Mobility Predictor Tutorial­ Dayton Artificial Limb”.
https://www.youtube.com/watch?v=Y7V8nJraUYc​ Online Video Clip. ​Youtube. ​Youtube, 7
Nov. 2012. Web. 18 Jan 2016.
Bureau of Labor Statistics, U.S. Department of Labor, ​Occupational Outlook Handbook,
2016­17 Edition​, Orthotists and Prosthetists,
on the Internet at ​http://www.bls.gov/ooh/healthcare/orthotists­and­prosthetists.htm​ (visited
January 18, 2016​).
"Children's Chair Little Scholar Kids Adjustable Chair." ​Www.reo­smart.com​. Web. 20 Jan.
2016. <http://www.reo­smart.com/PostureDesks_pink_fully_Kids_Adjustable_Chair_p/pc­318
­pk.html>.
"Faux Leather Tufted Swivel Adjustable Air Lift Dining Chair." ​Houzz​. Web. 20 Jan. 2016.
<​http://www.houzz.com/photos/21682685/Faux­Leather­Tufted­Swivel­Adjustable­Air­Lift­Dini
ng­Chair­Black­contemporary­dining­chairs​>.
Gailey RS, Roach KE, Applegate EB, et al. The amputee mobility predictor: an instrument to
assess determinants of the lower­limb amputee's ability to ambulate. Arch Phys Med Rehabil.
2002;83(5):613­627.
Wall, James C., PhD, Churan Bell, BS, and Jennifer Davis. "The Timed Get­up­and­go Test
Revisited: Measurement of the Component Tasks." ​VA Research & Development​. Journal of
Rehabilitation Research & Development, Jan.­Feb. 2000. Web. 18 Jan. 2016.
<http://www.rehab.research.va.gov/jour/00/37/1/wall.htm>.
22

24. Appendix 4.
User Observation
8 members of the DTC Section 15 class went to the Rehabilitation Institute of Chicago’s
pediatric orthosis center on Thursday, January 21st, 2016 at approximately 3:00 pm. They spoke
with client Julianna Mandle. The purpose of the visit was to make observations of the facility
and to observe the Timed Up and Go (TUG) test. The session lasted an hour. This appendix
summarizes the methodology of the visit, information about the user, and details of the TUG test.
Methodology
First, Ms. Mandle along with a fellow orthotist sat down with the team to discuss current
shortcomings of the TUG test. The two professionals shared their necessities and concerns with
regard to the chair they would like to have desined. Unfortunately, Ms. Mandle was unable to
find any volunteers for the TUG test. Instead, the team pretended to be the patient and they were
given the TUG test. The dimensions of the room in which the chair will sit were approximated
and a tour of the rest of the facility was given.
Information about the user
The test will most commonly be done on children with cerebral palsy or spina bifida. The users
are between levels I and III on the ​Gross Motor Function Classification System (GMFCS). The
TUG test is not currently performed within the pediatric population because of the lack of
standardization. ​The team was unable to meet a user during their visit.
Conducting the TUG
The team was unable to view a user perform the TUG test. Instead, Ms. Mandle performed the
TUG test on two members of the DTC team. The steps in conducting the TUG test are:
1. The chair is brought out of a clinic room and into the main hallway.
2. The chair is placed on a designated TUG marking on the floor.
3. The user sits with his/her back against the chair.
23

25. 4. At the signal of the orthotist, the user rises and walks to the designated TUG marking that
is 3 meters away.
5. The user turns around and returns to his/her seat.
6. The orthotist stops the time when the user’s back is once again touching the back of the
seat.
Shortcomings of the test
In the observed TUG test with two members of the team that varied in height, it was very clear
that their joint angles differed when sitting comfortably in the unadjustable chair. The first team
member’s ankles made a degree larger than 90 as she is unable to place her feet on the ground.
The second team member was contrastly able to comfortably place his feet on the ground and
maintain an ankle degree of 90.
Team Member 1 Team Member 2
24

26.
The TUG test was conducted in the hallway.
Team Member 1’s prioritized notes of her TUG test:
1. Distance between the armrests was too far
a. Her arms could not comfortably touch them, which means she could not really use
them to help her stand up
2. Seat was too tall and too deep
a. Her legs could not touch the ground
25

27. Appendix 5.
User Testing Report
Purpose
The purpose of our first round of user testing was to determine what kind of adjusting
mechanism will be the easiest for the physicians at RIC to operate. We wanted to learn about two
things: (1) which design would the physicians prefer and why they prefer it, and (2) whether
there are any design requirements that we have overlooked.
Test Methodology
Three team members dropped off our three initial mockups at RIC during the week of February
3. The first mockup was constructed of the base of an office chair and a foamcore back and arm
rests. It adjusts mainly by a sliding mechanism. The second mockup was also constructed of the
base of an office chair and foamcore back and armrests, but uses slots as the main adjustment
method. The third mockup is made of a plywood reinforced base, cardboard pillar, and foamcore
seats and armrests. It adjusts by a sliding mechanism, but differs the first mockup by the way
height is adjusted and the location the armrests and seat slides are placed. Below are the photos
of the three mockups.
26

28.
Figure 1: The first mockup.
Figure 2: The second mockup.
27

29.
Figure 3: The third mockup.
The tests were conducted in an RIC clinic room. The team members each gave a presentation to
the client about how each adjusting mechanism works, then the client tried to adjust each of the
chairs and provided feedback and concerns. The team members then discussed those concerns
with the client.
The team then left the first mockup at RIC for more physicians to try out, but took the second
and third mockups back due to the lack of space in the RIC clinic.
Results
The client provided feedback about each of the mockups regarding usability, convenience and
safety.
For the first mockup, the client provided the following feedback:
1. Using the raising/lowering mechanism on an office chair is a good concept.
2. The chair is strong enough and tall enough to support larger kids.
3. Liked that the design does not have removable parts.
And expressed the following concerns:
1. Having the 5 arms radiating from the base of the chair isn’t ideal. For kids with assistive
devices (walkers, crutches), the multiple arms will get in the way.
28

30. 2. Since the back is only held up by a single nail or screw, there is concern for stability if a
kid were to sit down quickly or in an uncontrolled manner.
3. As an office chair, the height won’t go low enough for little kids. Make absolutely sure
that the base is strong and stable enough that it won’t tip or rock if a disabled kid were to
push down on the chair.
For the second mockup, the client provided the following feedback:
1. Using the raising/lowering mechanism on an office chair is a great concept.
2. The chair is strong enough and tall enough to support larger kids. It’s great that there isn’t
concern that the seat will collapse.
And expressed the following concerns:
1. Having the 5 arms on the base of the chair isn’t ideal. For kids with assistive devices
(walkers, crutches), the multiple arms will get in the way.
2. As it is right now, the height won’t go low enough for little kids.
For the third mockup, the client provided the following feedback:
1. Very well thought out in terms of adapting all parts of the chair. It’s very adjustable.
2. The back of the chair is properly stabilized.
3. The base appears well balanced and stable.
And expressed the following concerns:
1. Having a single upright, rather than 4 legs, is a concern for stability by many of the
practitioners. Worried about the weight of kids and teenagers would be too much for this
design. The need for stability and safety is imperative. Same concept goes into play when
choosing materials.
2. There is concern for stability of the back of the chair if a kid were to sit down quickly or
in an uncontrolled manner. Make sure that your stabilization mechanism can withstand
some force.
29

31. Analysis, Conclusions, and Limitations
Analysis of results.​ The client preferred the overall design of the first mockup, and raised
concerns about the safety of our designs.
1. Adjusting mechanism: The client preferred the use of a sliding mechanism because it
allowed the chair to stay in a single piece during adjustment. This mechanism is easier for
physicians to operate and will not carry the risk of misplacing parts during adjustment or
transportation.
2. Safety of the design: The client expressed concerns about the safety of the chair. The
safety of the chair is imperative because the chair will have to support individuals with
various physical disabilities. The chair must be stable and can withstand weight, but at
the same time does not interfere with the use of assistive devices. We should keep this
principle in mind when designing the seat base and selecting materials to build the chair.
Conclusion.​ The result suggested that we should build on the sliding mechanism and should
make adjusting the chair easier and quicker for the physicians. It also suggested that we should
make the stability of the chair our main concern when designing future prototypes. We should
also put more thought into how the chair can accommodate patients with assistive devices.
Limitations.​ One limitation to our testing methodology is that because the current materials of
the mockup are not strong enough, it cannot be tested fully. It was not safe for patients to sit in it,
so feedback is limited to the convenience and usability of the design. Important information that
we would like to know, such as the durability and comfort of each design solution was not given.
Another limitation is that the second and third mockups was only tested by one physician, since
we had to take it back due to the lack of space at the office. Only the first mockup received
testing from multiple physicians, and the evaluation we received for the other two designs could
be more biased and more based on speculation.
30

32. Appendix 6.
Instructions for Usage
1. Before the setting up the chair measurements, the therapist should measure the child’s leg
length (from bottom of foot to knee), shoulder height, frame length, and thigh length
(important for seat depth) in inches
2. Begin by setting up the height of the chair.
a. If the child’s leg length is less than 18.25 in, remove the first pin from the spine
and adjust the spine vertically by raising the seat. Center the seat so that the pin
can re­enter the spine at the corresponding height on the spine (note that there is
an inch separation from each hole). Then place the pin through the spine.
b. If the child’s leg length is greater than 18.25, go through the instructions in Part A
but maximize the height of the first telescoping component by raising the seat
until the final pinhole is still inside the spine. Place the pin at this height. Then,
repeat step A using the second, middle telescoping component; removing the
second pin and adjusting the seat until it reaches the height between 18.25 in and
the maximum height the chair reaches that is required. Place the pin inside of the
spine at this height.
(Fig 1. Demonstrates how the telescoping mechanism, and how the pins fit into the holes and
lock about them.)
31

33. 3. Adjust the back depth. Remove the pin from the railings of the chair. The back should now
slide along the seat freely. Using the measurement for the thigh length, place the back at the
closest desired distance. Place the pins inside of the railings in seat.
(Fig 2. Demonstrates how the pins fit through the railings to keep the back in place.)
4. Have the patient sit down in the middle of the seat of the chair. Place the arms in the slot such
that the arm does not touch the back while being as close to the back of the chair lengthwise.
Widthwise, the arms should be slightly wider than shoulder length of the patient. Using the same
pin and lock mechanism from before, adjust the arm height such that the patient can comfortably
place their forearms on them.
5. Ensure that all ninety degree sitting angles are as they should be. The patient is now ready to
begin the TUG test.
32

34. Appendix 7.
Instructions for Construction
Instructions for constructing the prototype:
Materials:
Table 1: Materials used for Construction:
Materials Specifications Quantity
Heavy Duty Steel
Bolt­Together Framing
2” Square Tube, 4’ Long 1
Heavy Duty Steel
Bolt­Together Framing
1.75” Square Tube, 4’ Long 1
Heavy Duty Steel
Bolt­Together Framing
1.5” Square Tube, 4‘ Long 1
Plywood Sheathing ½” (15/32) x 4’x 8’ 2
Pony Adjustable Clamps 5"
Carriage C­Clamp
5” Opening, 3.25” Reach 2
Bolts [Inches] Long, “ Diameter 4
screws carbon steel wood screws 30
Pins with wrap­around lock .37” diameter, 6” long 4
Note: See Bill of Materials for more detail on cost and specifications.
The following tools/equipment are required for constructing the chair:
Band Saw
33

35. Water Jet
Power Sander and Sandpaper
Mallet
Screwdriver
Handdrill
Dremel tool
Level
Mill
Welding station
Metal bender
[Reference: Length is parallel to direction user faces, width is perpendicular, height is vertical
direction]
Dimensions:
Base:
Width: 24 in; Length 22 in; Thickness; 1.5 in. Width of H extensions (parts that stick out from
main part of the base): 4 in; Length, 6 in.
Depth of Hole: .75 in; center of hole is 12 inches from width of the base, 11 in from the
maximum (including H extensions) length of the base.
Telescoping mechanism fits inside: middle layer: height: 8 in; width and length: 1.75 in;
Outermost tube: height: 4 in; width and length: 2 in;
Innermost tube: height 9 in; width and length: 1.5 in.
The holes in the telescoping mechanisms have diameter: .43 in and are .57 in away from each
other.
Flanges attach to the outer layer.
Two flanges have these dimensions ­ length: 3.9 in; width: 1.85 in; height: 3 in; thickness; .36 in.
Two flanges have these dimensions – length: 3.15; width: 1.85 in; height: .99 in; thickness: .36
in.
Seat:
Below the seat, the inner telescoping mechanism is attached, with dimensions – height: 8 in;
width and length: 1.5 in.
The flanges attaching the inner mechanism to the seat have dimensions­ height: .7 in; length: 6
in; width: 1.3 in; thickness: .25 in
34

36. The Seat Itself has a width of 22 in; length of 22 in; thickness of 2.125 in.
The pegboard holes have width and length of 1.9075 in with a depth of 1.5 in;
The seat rails have a length of 22 in; width of .75 in; height of 1.75 in.
The arm rest themselves have a height of 1.55 in and consist of two layers, the top which has
length: 9 in and bottom which has length: 7 in. The width of these are 2 in.
For the telescoping mechanisms on the arms, the outer layer has height: 9 in; width/length: 1.75
in. The inner layer has height: 6 in; width/length: 1.5 in.
The pins themselves have a diameter of .385 length: 2.5 in and pinhead has diameter of .625,
Back support:
Back support (lowest part of extending part, touches actual seat): height: 1.55 in; length:5.9 in;
width: 1.57 in.
Middle support (faces same direction as back support, visualized as a trapezoid): height: 1.56 in;
below length: 4.7 in; upper length: 4 in; angled length: 1.7 in.
Attached to back: height: 11.6 in; width: 1.57 in; length: .77 in.
Triangle piece (visualized as trapezoid to an extent): long length (hypotenuse): 11.6 in; top base
length (part close to the back­facing vertical direction): 3.9 in; bottom length (part closer to seat):
2.4 in; Angle: 60 degrees.
Back:
Width: 23.375 in; Height at maximum point: 20.5 in; Radius of hole: 3 in; Diameter: 6 in.
Radius of curve: 11.6875 in;
Fig. 1: The Base Fig. 2: Telescoping Component connected to Base
35

37.
Fig. 3: Telescoping Mechanism attached to Seat Fig. 4 Seat and Base Telescoping Mechanism
Fig. 5 Seat Fig 6. Close Up of the Seat and Railing
Fig 7. Arm Components and the Seat Fig 8: Arm Locked in Place
36

38.
Fig 9: Side view of Arm Fig 10: Unlocked Pin
Fig 11: Locked Pin Fig 12: Front view of Back
Fig 13: Back View of Back Fig 14: Side View of the Back
37

39.
Fig 15. Using a bandsaw to cut the railing Fig 16. Applying Wood Finish to the Seat
Fig 16. Sanding the Seat Fig 17. Cutting the carbon steel with the bandsaw
Fig 18. Crafting the telescoping mechanism with the bandsaw
38

40.
Fig 19. Constructing the Base Fig 20. Cutting down the Base into an H shape
Fabricating the components:
1. Chair Base:
1. Cut 1.5 inch plywood into two H­shaped bases using a waterjet.
2. For one of the wooden slabs, cut out a 1.75 by 1.75 inches square in the middle by
using a waterjet.
3. Combine the two pieces by placing the slab with a square on top and screwing both the
layers together with 1 ⅝ wood screws.
4. Drill four holes on the base with a ⅜’’drill bit.
2. Telescoping pillar:
1. Of the three sizes of tubes, cut the tube with the smallest cross section into a 9 inch
tube, the one with the medium cross section into a 8 inch tube, and the largest one into a
4 inch tube.
2. Drill four hole on the smallest tube with a ⅜’’ drill bit 1 inch down the tube. These will
be used to install the top flanges.
3. Slide tubes with a smaller cross section into tubes with a larger cross section.
3. Seat:
1. Using a waterjet, cut out three 22 by 22 inches squares of plywood.
2. For two of those slabs, cut peg holes into the piece.
3. Combine the three pieces by placing the two pieces with peg holes on top and screwing
the three layers together with 1 ⅝ wood screws.
4. Railings:
1. Cut wood into two pieces of 22 inches in length, .75 inches in width and 1.75 inches in
height.
39

41. 2. For both of those pieces, drill holes along the 1.75 by 22 inches surface, with each hole
2 inches apart using a ⅜’’ drill bit.
5. Armrests:
1. Cut two pieces of wood of dimensions 1.5 by 2 by 7 inches.
2. Cut two pieces of wood of dimensions 1.5 by 2 by 9 inches.
3. But the medium and small size telescoping tubes into two 6 inches and two 9 inches
long pieces.
4. For the two shorter pieces, cut a square out in the middle of the pieces using a
bandsaw.
5. Combine the pieces by placing each shorter piece of wood under a longer piece and
screwing them together with wood screws.
6. Connect the tubes and the wooden component by sliding the smaller tube into the
square on the wooden component. Then, slide the larger tube onto the smaller one.
6. Seat back:
1. Cut out the flat surface of the seat back using a waterjet.
2. Construct the two back supports By cutting out four pieces of wood of dimensions:
Back support (lowest part of extending part, touches actual seat): height: 1.55 in;
length:5.9 in; width: 1.57 in.
Middle support (faces same direction as back support, visualized as a trapezoid): height:
1.56 in; below length: 4.7 in; upper length: 4 in; angled length: 1.7 in.
Attached to back: height: 11.6 in; width: 1.57 in; length: .77 in.
Triangle piece (visualized as trapezoid to an extent): long length (hypotenuse): 11.6 in;
top base length (part close to the back­facing vertical direction): 3.9 in; bottom length
(part closer to seat): 2.4 in; Angle: 60 degrees.
Screw the pieces together in the way shown in fig 14. Then, drill a hole in the middle
bottom of the back support using a ⅜’’ drill bit.
3. Connect the back support with the back by screwing the back supports onto the bottom
of the base. See fig 14.
7. Flanges:
1. Cut 4 pieces of aluminum of dimensions:
Two of four base flanges have these dimensions ­ length: 3.9 in; width: 1.85 in; height: 3
in; thickness; .36 in.
Two of four base flanges have these dimensions – length: 3.15; width: 1.85 in; height: .99
in; thickness: .36 in.
using a band saw.
2. Bend the metal 2 inches in along the length of the metal.
3. Drill a hole on the shorter side of the metal and two along the long side using a mill.
These will be the base flanges.
4. Cut 4 pieces of steel of dimensions:
40

42. height: .7 in; length: 6 in; width: 1.3 in; thickness: .25 in
using a band saw.
5. Bend the metal 1 inch in along the length of the metal.
6. Drill a hole along the long side using a mill. These will be the seat flanges.
Putting the chair together:
1. Insert the telescoping tubes into the base by pounding the tubes into the cut out square.
The end in which the extra holes are drilled on the smallest tube must be placed on top.
2. Place the four steel flanges against the four sides of the tube and the base.
3. Weld the flanges onto the tube.
4. Secure the flanges onto the base by inserting a pin through the holes on the flanges and
the base.
5. Install the top flanges by screwing them into the holes previously drilled on the smallest
telescoping tube.
6. Install the seat by inserting the seat onto the telescoping tubes and securing the flanges
with screws through the flanges and the seat.
7. Install the rails by attaching them along the edge of the base with wood screws, .75 by 22
inch surface facing down.
8. Place the seat back on top of the seat, with the back supports parallel to the rails.
9. Insert armrests into two of the peg boards.
41

43. Appendix 8.
Executive Summary
Problem
The Timed Up and Go test is an outcome measure test that measures the progress of physical
therapy. In order for the test to function properly, the patient’s body must be positioned such that
the​ ​arm, hip, and leg angles are at a 90​° angle while sitting with his or her back against the chair.
Although a standardized chair exists for adults, a standard from ages 3­15 does not exist due to
the extreme differences in body sizes that exist. Thus our client, Julie Mandel of the
Rehabilitation Institute of Chicago, asked us to design and construct a chair that could be
adjustable to all body sizes of people age 3­15.
Research and Testing
Our group’s background research involved the two tests the therapists specifically need the
chairs for—the Timed Up and Go Test, and the Amputee Mobility Predictor, and models of
chairs also designed to be adjustable. We developed four mockups for our client to view so we
could see the strengths and flaws and each design and understand which types of designs our
client preferred.
Design Overview
Our design features an adjustable telescoping mechanism, or multiple pin­and­lock systems, for
the spine that allows the seat and arm height to adjust. The seat depth is adjustable by changing
the back depth. The back is allowed to freely slide about the seat, and is clamped to the side of
the seat when the user sits. The arms fit inside a peg board system which allows the user to easily
move the arms to fit body proportions.
Requirements
Adjustability​ – The seat height and depth and arm height, width, and depth are all easily and
fully adjustable.
Portability – The chair is comprised of various detachable parts which allows for easy storage.
Stability and Security – The chair does not hinder use of assistive devices. With proper
components, the chair is stable and able to sustain 180 pounds of force.
Ease of Use – The chair is easily adjustable by one person and can be easily sanitized by alcohol.
42