The document describes a design need to help people with arthritis open and organize keys more easily. Currently, tasks like finding the right key, gripping it, inserting it into the lock, and turning it require hand movements that can cause pain. The document then outlines initial designs for a key aid device, including levers and sliding mechanisms to reduce the need for painful finger motions. It discusses refining the designs based on feedback, including making ergonomic improvements to ensure the device fits most hands comfortably without requiring squeezing or other painful gestures.

1. 1
Inclusive Design
/// Criteria B
Higher Level Design Technology
Irvin Acosta Year 12

2. 2
Task A1 Design Need
Problem
A common everyday task everyone faces involves securing doors, chests, and closets using conventional
pin and tumbler locks, the most common locks used in households. However, this simple but crucial task
may pose significant difficulty to people with arthritis due to the current design of the keys in the market.
Avoiding these tasks to avoid pain can compromise their security. A common way of organizing keys is by
grouping them with a keychain. Finding the correct key requires extra movement and more potential pain.
The task of inserting, then turning the key to unlock a pin and tumbler lock requires hand movements
which cause pain, with varying pain levels depending on severity of the condition.
This task can be broken down into these hand motions (listed in chronological order):
1. Pinch (To grip the key)
2. Push (Inserting key into keyhole)
3. Twist (To rotate the key in the tumbler in order to unlock)
4. Pull (To remove key from the keyhole)
Usually, people will often have multiple keys held by one keychain. Finding the right key will often require
fine finger movements. Because of arthritic peoples’ limited finger dexterity, the task of organizing keys
can be time consuming and painful.
The listed actions put pressure in sensitive joint areas and cause pain. People with arthritis have limited
finger motion range. This causes restricted joint movement, and ultimately, usability of many general
consumer products.
The product that will solve the issue of operating and organizing keys will be an extension of the keys that
the market is currently using.

3. 3
Task A5 Product design specifications
Specification Justification
Must take less than 5 steps to
operate device
Low memory burden leads to ease of use and customer loyalty
Device must not require the user to
move fingers joints at painful
angles
Small objects require the user to grasp tightly in order to grip it,
which in turn would cause pain
Most sizes of keys must fit in the
device
In order to accommodate a larger market, all sizes and
dimensions of conventional house keys must fit in the device
Must use minimalist design The choice of using minimalist design can be used as a
marketing tactic to make the product seem less “intimidating”
and improve its marketability among the older segment of the
potential target market.
The product must eliminate need to
pinch to grip the key securely
Pinching movements usually add strain to sensitive joints. In
some cases, pinching may not be possible due to restricted
joint movement.
The product must reduce the use
of wrist in turning the key when
locking and unlocking the door.
Turning the key while the user is pinching the key adds
additional strain to sensitive wrist joints. Pain must be
minimized
Must be easily portable and fit
small bags
The device will be brought around and used daily
Device must be fully disassembled
with common tools
This will help speed up the salvaging / recycling process
Must be durable and withstand
repetitive use and strain
Item will be used often (strengthening ribs)
Must be ergonomic for majority of
users
To maximize the marketability of product, the aid must be
comfortable to use for majority of the users. Anthropometric
data falling in the 50
th
percentile should be used to
Must hold more than 4 keys To maximize user’s product use, it must accommodate more
than 4 keys
Must allow user to choose from
multiple keys easily
Rifling through multiple keys requires potentially painful finger
movements. The aid / solution must reduce fine finger
movements required to choose appropriate key
Product must not contain sharp
edges
Sharp edges can cause scratches, discomfort to user

4. 4
8 Initial Designs
Idea #1
Idea #2
Idea #3
Idea #4
Function:
- Ergonomic grip w/ rubber handles
eliminates need to pinch keys to
when handling
- Rounded shape and larger
contact surface area minimizes
need to curl fingers in painful
angles
-
Function
- Lever action translates painful pinch
and turning motion into painless push
down motion
- Rubber handles allow for more
secure grip
Function
- User twists product to choose key, then
pushes “plunger” to extend chosen key to
enter lock.
- Reduces finger dexterity required to
choose between 7 keys: Simplifies process
into one twisting action
Function
- User pushes the ejector to swivel one of 6
keys out – Simplifies key organization
through decreasing amount of steps needed
- Circle in middle allows user to grip item
securely and help act as a lever, decreasing
pain when unlocking door

5. 5
Idea #5
Idea #6
Idea #7
Idea #8
Function
-User slides one of 3 keys out, and retracts
when not in use to improve portability
-First layer slides out to increase surface
area and improve grip
-Card acts as a lever to ease key turning
movement and minimize pain
Function
-6 keys are fixed in a chain formation and
eject out of the slot when needed;
simplifying use
-Long body acts as lever
-Streamlined shape improves portability;
fitting into bags more easily
Function
-Four keys are installed in the slots. Key
ejects if corresponding button is pressed,
and retracts when not in use
-Keys are retractable to make product’s form
more streamlined and more portable
Function
-Five keys swivel out to be perpendicular to
body, and act as lever when turning key -
-Pentagon shape allows user to place each
finger on edge comfortably and divide
turning force to whole hand, decreasing pain

6. 6
Task B1b Development of Solution
Improvements Based on Feedback
Issue
Turning might be difficult due to the product’s smooth,
cylindrical shape. This is multiplied by the users’ inability to
squeeze to grip the item when twisting it
Suggested Solution
Turning the front part can hurt because of need to squeeze
- lever eliminates need to squeeze when rotating key. The
lever effectively translates rotational motion into a more
comfortable, pushdown motion, which instead uses the
whole arm, instead of flexing sensitive finger joints.
The lever however, must be foldable to minimize used
storage space when not in use
Issue
Sliding out the keys using a pinching finger gesture can
hurt due to the arthritic user’s inability to flex fingers.
Solution: Foldable Lever in the place of ejectors can
eliminate need to squeeze when pulling out key ejectors
Curved edges can help place fingers better around form;
decreasing need to squeeze (which causes pain) to have a
sturdier and tighter grip.
Issue
Sliding out grip might be an issue because of need to make
pinching motion with fingers.
Issue applies for the key ejectors
-Slide-out grip is not ergonomic: sharp edge adds
pressure in small area of palm, causing discomfort
Suggested solution: Foldable attachment lever to grip and
sliders could be made to eliminate painful pinching hand
movements.
The lever must sit flush with the item so that the
requirement of a low storage space is met.
Larger fillet radius in thumb edge allows thumb to conform
to card shape more comfortably

7. 7
Design 1 Revised
Additional research: In order for the card to fit the hand comfortably and snugly, I needed to research
appropriate anthropometric data. I needed to research average finger widths in order for the majority of the users’
fingers to fit the curved, indented edges properly. The circumference of the arcs intended to hold the fingers must be
equal to the average finger widths. If the arcs are too large, the grip would become lose and if the arc circumference
is too small, the fingers would not fit and would be harder to grip.
The purpose of using the appropriate measurements for the indented finger arcs is to increase the surface area in
which the fingers make contact with the card, which improves grip stability. Averages are used in order for the
product to conform to majority of users’ hands comfortably; improving marketability and user experience
The average thumb length determines the pull out handle’s fillet radius. The appropriate curve allows the users’
hands to conform comfortably to the shape of the card grip area.
Anthropometric Data Used (Bodyspace 3rd
edition)
Dimension (mm) Men (50
th
Percentile) Women (50
th
Percentile) Average
Finger Breadth 22 18 20
Thumb Length 51 47 49
Ergonomics Evaluation
Positives:
-Fits my hand well because the sliding grip adjusts specifically
for my hand’s length
-Filleted corner allows thumb to rest comfortably
Areas of Improvement:
- Arc only accommodates fingertips, base of fingers is too large
for the arc – this must be enlarged to fit comfortably
- Fairly sharp corner can cause discomfort on palm if held for
extended periods of time – This can be filleted to a larger radius
to disperse force put on palm to a larger surface area and
reduce pain

8. 8
Design 2 Revised
Evenly spaced
indented arcs
around
circumference
allow area
between thumb
and index finger to
sit securely
regardless of
hand’s grip and
positioning.
Folding and rotating lever allows user to eject key without needing to
pinch button in previous design, which can cause pain due to the
sharp angles that the finger joints need to do. User can use their palm
or fingertip to push lever without making painful hand gestures
The hinge joints allow the lever to sit flush to the
product’s form when not in use; allowing the product to
be stored in small, tight spaces. Revolute joint allows
lever to change direction, based on whether ejector is
being pushed in or out
Ergonomics Evaluation
Areas of Improvement:
-Although the thumb sits comfortably on Design 2’s
curvature, the item forces the pinky and index
finger to split, which can cause pain, especially
when the user tries to squeeze the object to
increase grip.
- This can be addressed by decreasing the
diameter of the object based on the size in
which the 50
th
percentile of users can grip
the object without causing pain
- An arc can be placed here to allow pinky to
rest and eliminate need to curve pinky finger,
which can cause pain in arthritic hands

9. 9
Design 3 Revised
Lever swivels out via a hinge joint. User can press
down on lever, which converts vertical movement into
rotational motion, which unlocks the door lock once the
key is extended.
After the handle is used, and is no longer
needed, the handle can fold to fit flush with
the product’s form, minimizing storage
space use and maximizing portability
User’s four fingers
can fit inside the arc.
User does not need
to flex finger joints,
and instead keep it
at a flat, comfortable
position to push
down lever, that
does not cause pain
Ergonomics Evaluation
Areas of Improvement:
-The circumference of area is too large for my hand, which
causes my hand to shift downwards in a more comfortable and
secure grip. The shift in position however, causes my palm and
wrist to interfere with the sliding cylinder and the ejection of the
key
This issue can be addressed by reducing the circumference of
the upper area and prevent user from shifting their grip lower to
the point where it interferes with the sliding cylindrical joint.
-When gripping the object tightly, my hand had a tendency to
slide down because of the object’s inclined form.
-This can be addressed by modifying the form so that both
opposing edges are parallel, preventing shift. A cylindrical form
ensures a more secure grip
-Adding a textured or rubberized grip can also secure grip and
prevent shifting of hand

10. 10
Task B1c Appraisal of solutions against specification requirements
Specification Design 1 Design 2 Design 3
1) Function 1) Must take less
than 5 steps to
operate device
4/5
Needed 6 steps to operate
device
5/5 3/5
Takes 3 steps to operate
device
2) Device must not
require the user to
move fingers joints
at painful angles
3/5
Due to small size, fingers
may need to bend more
4/5 5/5
Ergonomic body contours to
hand shape
3) Most sizes of
keys must fit in the
device
5/5
Clamp mechanism allows
keys of varying
thicknesses to fit
2/5
Size of peg holding
the key is fixed.
Smaller and larger
keys may not fit
4/5
Irregularly shaped keys will
not fit, but most should
4) The product must
eliminate need to
pinch in order to
grip key securely
5/5 5/5 5/5
Product fits will in hand
without
5) The product must
reduce the effort
required to turn the
key
2/5
Although grip is improved,
product still needs to be
turned via rotation of wrist
2/5 5/5
The “effort” arm is longer,
meaning less effort is
required to offset load
6) Must allow user
to choose from
multiple keys easily
4/5
Requires 3 steps to
extend key
4/5
Simplifies process
into pushing ejector
to extend keys
5/5
Process is simplified by
reducing into 1 type of motion
7) Must hold more
than 4 keys
3/5
Can only fit 3 keys, but
compensated by its small
size
5/5
Holds 6 keys
5/5
Product can hold 2 more keys
above minimum
requirement
8) Must be
ergonomic for
majority of users
4/5
Slide out grip length can
be variable, fitting a wide
range of hand lengths
5/5
Aid can be gripped
differently but
securely based on
hand size
5/5
Product can accommodate
most sizes of hands
2) Aesthetics 1) Must use
minimalist design
5/5 3/5 5/5
Few, simple lines and curves
only utilized in design
3) Size 1) Must be easily
portable and fit
small bags
5/5
Fits in wallet, based on
credit card size and
dimensions
3/5 3/5
4) Environment 1) Device must be
fully disassembled
with basic tools
2/5
Uni-body construction
means parts are not easily
salvageable due to difficult
access
3/5 4/5
5) Performance 1) Must be durable
and withstand
repetitive use and
strain
3/5
Small hinges may wear
down after repetitive use
3/5 4/5
6) Safety 1) Must not contain
sharp edges
3/5 3/5 4/5
TOTAL 48 / 65 47 / 65 59 / 65

11. 11
Chosen Design Justification
Although design 3 may be less portable due to its irregular shape, it compensates for its superior
ergonomics, simplified user interaction and low memory burden. Tactile and auditory feedback could be
utilized through incremental clicks that notify user that chosen key is aligned and ready to be extended.
These various features simplify user interaction and is more appropriate for the older age range where
cognition, memory and physical ability is limited. Design 3 is also the only design that reduces wrist
movement required to unlock door.
A point in which design 3 excels at is the number of steps required to operate product. The spring loaded
cylinder joint halves the required steps because retracting the moving parts after use has been
automated. Since it requires the lowest amount of steps to operate the product, it also has the lowest
memory burden. A low memory burden improves the user experience by simplifying user interaction.
Design 3 overall, is the simplest in terms of user interaction. It effectively solves the issue of managing
keys by simplifying the process through translating otherwise uncomfortable hand movements into more
manageable pushing and turning motions.

12. 12
Task B2a Development of Design
Part #1 – Main Body
Function: To house internal parts and serve as an ergonomic body for user to handle
1st
Iteration Improvements
1) Window A has been added, allowing
user to easily access and rotate key
cartridge
2) Window B has been added to give
user a visual indicator when the key slot
has aligned with the key pusher /
plunger (client issue 1)
3) The main body consists of two
separate parts for easier accessibility
(Spec 4.1) and assembly. Addresses
client issue of fixing jams (client issue 2)
2nd
Iteration Improvements
1) Part A has been filleted to
prevent sharp edge from
scratching user when user’s finger
slides to rotate cartridge and meet
specification 7.1
2) Window A has been duplicated
in opposite side. This helps
disperse pressure required to
more than one finger, decreasing
pain
(Spec 1.2)
3) Window A is enlarged to
improve ergonomics and fit larger
fingers (Spec 1.8) (client issue 3)
A
B
Client Interview Main Points:
1) Hard to tell if key is aligned with ejector
2) Product could jam due to moving parts
3) Part A could be hard to access due to small size

13. 13
Part #2 – Key Pusher
Function: Part allows user to eject the selected key from the cartridge (Part #3) via a
pushing motion
1st
Iteration Improvements
1) Part A has been removed to
ensure that the plunger can be
disassembled from the upper
body
A
2nd
Iteration Improvements
1) Part B is hollowed out to reduce
plastic use
2) Part C is enlarged to prevent
part from wearing out and
potentially breaking (Spec 5.1)
3) Part D has been changed into a
circle to streamline the form and
improve portability (Spec 3.1),
solving client issue #1
B
C
D
Client Interview Main Points:
1) Potential issue with portability due to sharp angled edges (edges
could snag with cloth)

14. 14
Part #3 – Key Cartridge
Function: Cartridge houses each key while pivoting on one point to allow user to rotate
to choose key to eject
1st
Iteration Improvements
1) Part A has added to ensure
that the user grips the cylinder
securely with minimal effort and
pain (Spec 1.2) (client issue 1)
2nd
Iteration Improvements
1) Part B has been added to
allow user to label
corresponding key with a
marker. Part B can be seen
through the main body to
indicate that desired key has
been aligned with key ejector.
(Spec 1.6)
A B
Client Interview Main Points:
1) Smooth plastic surface might be slippery, when oils from fingers
accumulate

15. 15
Task B2b Validation of Design Proposal
Specification Evaluation
1) Function 1) Must take less than
5 steps to operate
device
The product only requires 3 actions to operate it: Rotate Cylinder, Push
and Eject Key, Twist to unlock. Adding the spring to push the plunger in
its neutral position cut down an action since it has become automated by
the spring. The product is effective because it does not consume lots of
time to operate
2) Device must not
require the user to
move fingers joints at
painful angles
The cylindrical form of the product fits naturally because of the inherent
shape of users’ hands. The narrower top of the body allows the shorter
fingers (pinky and ring finger) to conform to the product’s shape. The
product allows users’ hands to conform naturally to the product’s shape,
minimizing potential discomfort when gripping the product
3) Most sizes of keys
must fit in the device
The slots in the cartridge can accommodate most keys in the market. The
slot size is based on the largest keys’ dimensions. Assuming that the
sample of keys used in the measurement of the slots, reflect the
dimensions of keys in the market, the cartridge should accommodate
majority of keys
4) The product must
eliminate need to
pinch in order to grip
key securely
The enlarged gripping surface area of the product completely eliminated
the need to make any painful pinching actions
5) The product must
reduce the effort
required to turn the
key
The off-center key ejection slot uses the body as a lever to decrease effort
required to turn the key. Although a folding handle cannot be incorporated
into the design (due to space limitations), the body can still be effectively
used as a turning lever (with the key being the fulcrum)
6) Must allow user to
choose from multiple
keys easily
The rotating key cartridge gives the user the freedom to choose the key
they want to use by aligning it with the ejector. Allowing user to label the
key slots decreases the memory burden. This saves time and effort when
choosing from multiple keys
7) Must hold more
than 4 keys
Due to the cartridge’s large circumference, 6 key slots can be fitted in
array. This is above the minimum required held keys
8) Must be ergonomic
for majority of users
In theory, the product should fit most users because anthropometric hand
data from the 50
th
percentile has been used. This is the maximum
potential users that the product meets
2) Aesthetics 1) Must use minimalist
design
The design style utilized in the product is not completely minimalistic due
to the multiple curves and other ornamentations used to improve
ergonomics and function. This specification has been met partially
3) Size 1) Must be easily
portable and fit small
bags
Due to the product’s regular shape and filleted edges, the product should
be easily fit into bags. A hole for a lanyard has been added to give the
user the option to hang the product in the event that it does not fit the
user’s bag.
4) Environment 1) Device must be
fully disassembled
with basic tools
The device does not use glue, which means that no tools are needed to
disassemble the product, improving recyclability. The product exceeds
this specification requirement
5) Performance 1) Must be durable
and withstand
repetitive use and
strain
Moving parts have been improved by enlarging them to prevent any
cracks in the product’s weak points. This improvement should improve the
durability of the product and lengthen its life
6) Safety 1) Must not contain
sharp edges
All of the edges in the product has been filleted significantly which
eliminated all sharp edges and potential to injure or cause discomfort to
the user. The product meets the specification as required

16. 16
Task B2C Design Proposal
*ABS Plastic (injection
molded) used in all
components except
spring
Lap Joints (4x)
and glue
Slide Joint,
Lubricated to
reduce friction
Steel

17. 17