Braille-It Winter 2024 Design Journey Presentation.pptx

1. Braille-It
Design Journey
March 11, 2024

2. Agenda
I. Project Introduction
II. My Resources & Research
Process
III. Design Changes
IV. Lessons Learned

3. Project Introduction

4. Braille
➔ Writing system for the blind
➔ There are 132 different
languages with corresponding
braille writing systems

5. Braille Labels
➔ Braille, and braille labels, are an important tool for blind people to
navigate and organize their world, and achieve a higher level of
independence
➔ Current braille labelers require costly specialized tape, and are only
available in a few languages or very expensive

6. State of the Art

7. The “Braille-It”
1. completely independent braille dot selection -> language universal!
2. mechanical, made out of low-price materials -> affordable!
3. makes labels on Scotch magic tape -> accessible, low variable cost
4. can be used intuitively by a blind person -> blind user friendly

10. Top Housing →
Beams →
Anvil →
Scotch Tape →
(Bottom) Housing →
← Ratchet Wheel
Rollers

11. Project Goals
1. Improve user friendliness
2. Improve mechanical function and durability
3. Design for affordable volume manufacturing

12. My Resources & Research Process

13. Advisors & Consultants
➔ Professor Robbie & Dr. Johnson project advising and design reviews
➔ Joe Poissant design workshopping and DFM review
➔ National Braille Press (NBP) & Perkins user testing, expert feedback
➔ Nevan Hanumara, Dan Gilbert, Chris Magoon, Hypertherm, et al
technical brainstorming and injection molding exposure

14. Interaction
Design
Sequence

15. Deterministic Design
➔ Revised and appended functional requirements (FR) based off of
mechanical testing, user testing, and manufacturing needs
➔ Determined design parameters (specific ways to achieve FRs) through
brainstorming, calculations, modeling, testing, and risk analysis

16. Legend
Black Part of Braille-It V1
Blue FRs I appended or revised
Bold Not achieved/tested yet
Functional Requirements (Events) Design Parameters ( Ideas) Analysis
Embossing
Precise Alignment between punch
and die
"+/-" 0.15mm evident in prototype
Force applied to die to emboss
scotch magic tape
10N of force Tested the stack with force meters,
can test again with Instron, also see
Appendix A.2
Repeated elastic bending 10^5 cycles see Cycles Needed Calculation,
pg. 9
Embossers fit dot model geometry see braille standards see braille standards
Dots can be created independently 6 actuators for 6 independent dots evident in prototype
Haptic feedback indicates dot is
created
tactile and audible click after 10N of
force to emboss dot is applied
evident in prototype
Dots do not tear/ are legible
when teared
Make sure dot embossing tip
radius is rounded and not overly
sharp
Make samples of labels, measure
percentage of teared dots + user
testing, measure percentage of
illegible dots from tearing

17. Functional Requirements (Events) Design Parameters ( Ideas) Analysis
Indexing
Move tape in discrete increments
for cell spacing
Intercell spacing of 6.2mm See if produced samples meet
standards 95% of the time with
alpha = 0.05
Provide haptic feedback to user that
spacing is achieved
tactile click after spacing is
achieved
evident in prototype
Tape exit doesn't interfere with
holding
Tape exits device out of the way of
hands
evident in prototype
Repeated elastic bending of the
pawl
10^6 cycles See Cycles Needed Calculations,
pg. 9
Tape is easy to grip during
indexing
Geometry of tape exit gap allows
99 pth male fingers to grip tape
with SF of 2.5
See Tape Gap Calculation, pg. 6
Tape
Cutting
Simple manual cutting motion only need to use one hand and
single motion
evident in prototype
Tape is easily accessible after cutting create an external tape resting face evident in prototype
Tape cuts easily on edge without
necking
2mm teeth for the cutting edge,
sufficient angle for cutting
evident in prototype
Tape doesn't split or tear after cutting teeth of the cutting edge do not
exceed 2mm
evident in prototype

18. Functional Requirements (Events) Design Parameters ( Ideas) Analysis
Holding
Fits in two hands meets ergonomic requirements for 5-
95% of users ages 15-65
user testing across broad range of
hand sizes
Dots writting in same direction and
orientation as they are read
Dots created upwards towards the
user
evident in prototype
All buttons can be used
simultaneously
all fingers fit on the buttons at the
same time
evident in prototype
Extended use does not fatigue user keep wrists and hands in neutral
(unstrained) position
user testing across broad range of
hand sizes
Easy to determine if device is held
in the correct direction
Device can be accurately and
reliably oriented by a blind person
in under 3 seconds
user testing
Tactile indications of which
button is which
dimples on 2 and 5 dots,
embossed letterings next to all of
them
user testing
Assembling
Parts must be assembled accurately
with precise alignment
"+/-" 0.15mm in the x and y sensitive
directions
evident in prototype

19. Functional Requirements (Events) Design Parameters ( Ideas) Analysis
Assembling
Parts are easily assembled in the
correct orientation by a
nonsighted person
parts designed to only fit one
way -- create asymmetrical area
for the tape, add protrusions and
locating bosses
user testing
Re-assembly, tape is easy to
replace
Can be done without sight in
under 5 min, <10 steps
user testing
Top housing and beams do not
easily come apart again after
initial assembly
Use screws, heat sinks, or just
extra intense snap fits for the top
housing and beam stack (2x force
to separate top housing and
beam than beam and anvil)
either evident in prototype, or
use force meters to measure
pulling force
Manufacturing
Low Cost All parts are injection moldable;
all parts are designed towards
simple two part molds; minimize
the need for EDM machining;
minimize part number; minimize
mold complexity
Mold models, mold flow analysis,
Protolabs quotes

20. Design Changes

21. Usability

22. FR: Improve Tape Handling
➔ Prevent tape from retracting
within housing
And make it easier to…
➔ Find, grip, and pull the tape
➔ Fit tape through the tape exit
during loading
➔ Figure out which direction to
load the tape in

23. Functional Requirements
(Events)
Design Parameters
(Ideas)
Tape
Handling
Prevent tape from
retracting within housing
create an external resting
edge
Make it easier to find,
grip, and pull the tape
create an external resting
edge, widen finger
handling space
Make it easier to fit tape
through the tape exit
during loading
wider tape exit, replace
protruding cutting edge
with a flush cutting edge
Make it easier to figure
out which direction to
load the tape in
Asymmetrical bottom
housing

27. Effective Tape Exit
Area = 567 mm2
Effective Tape Exit Area
= 732 mm2
Increased Tape Exit Area by 30%

28. Added Tape Resting Surface

29. Bonus: now it’s also easier to set down and balance the device

30. FR: Clarify how to assemble and position the device
DPs
➔ Asymmetrical bottom housing
➔ Tactile indication of
match/mismatch between the
top housing and bottom
housing
➔ Tactile logo to demonstrate a
“top”/ “front” side

32. FR: Add easier method of indexing than pulling tape
Strategy: control the rotation of the ratchet wheel with a knob/button instead
of tape pulling, the rotation of the ratchet wheel will in turn automatically
index the tape
Concepts:
➔ add external knob to the ratchet wheel
➔ Use a “clicky-pen” mechanism to translate linear motion into rotational
motion

34. Next Steps
➔ Add indications of “1, 2, 3, 4, 5,
6” dots to the top housing
buttons
➔ Optimize device size and tape
exit gap size to a wider range
of hand sizes

36. Mechanics

37. FR: Create Easy, Effective Tape Cutting Mechanism

38. FR: Prevent accidental over-indexing by increasing the pull force
➔ Pull force is the sum of ratchet
force and tape holding force
➔ Removing the rotating rollers
decreases sliding efficiency,
increasing the tape holding
force
➔ Pull force increases

40. Material Selection
ABS
➔ Affordable, durable, injection
moldable thermoplastic
➔ Holds up well to external
impact
➔ Less shrinkage than PP during
molding
Anvil, ratchet wheel, bottom
housing
PP
➔ Affordable, durable, injection
moldable thermoplastic
➔ Greater flexibility, better suited
for snap fits
Top housing, beams, anvil,
bottom housing

41. Next Steps
➔ FEA fatigue analysis of parts that experience repeated deflection, such as
the pawl and the cantilever beams
◆ 105 cycles for the beams, 106 cycles for the pawl
➔ Retest consistency and quality of braille labels

42. Estimating Cycles Needed

43. Manufacturability

44. FR: Minimize part number

45. FR: Optimize parts for injection molding
Bottom Housing
➔ Reduced the size
➔ Less intricate tape cutting edge
TBD:
➔ Continue optimizing the cutting
edge
➔ Less intricate fastening
mechanisms
➔ Add fillets to internal sharp corners

46. FR: Optimize parts for injection molding
Anvil
➔ Created space for a bypass mold
➔ Removed roller holder details
➔ Evened out wall thicknesses,
added smooth transitions
TBD:
➔ Improve mold flow to the pawl
➔ Less intricate fastening
mechanism
➔ Add drafts
➔ Optimize tape holder design

47. FR: Optimize parts for injection molding
Ratchet Wheel
➔ Minimize heat sinking
➔ Design for injection
molding with a central
parting line

48. Next Steps
➔ Determine optimal manufacturing methods for each part for low volume
and high volume production
➔ For parts that should be injection molded, make sure the designs are
injection moldable
➔ Validate with mold designs/mold flow analysis/Proto Labs
➔ Build a cost projection spreadsheet for 10, 100, 1000, 10,000 units per
year

49. Summary

50. Lessons Learned

51. ➔ Mechanic and kinematic designs and calculations
➔ CAD design and master modeling
➔ 3D printing and machining
➔ Rapid prototyping and testing
➔ Plastics manufacturing methods, DFM

52. ➔ Learning more about accessibility and accessible design
➔ Recognizing my design biases
➔ Benefit of user testing for highlighting focus areas
➔ Benefit of early prototyping, and also making free body diagrams
➔ Benefit of understanding manufacturing processes, and having that
inform design

53. Acknowledgements
★ Advisors and instructors at Dartmouth College and the Dartmouth
Machine Shop
★ National Braille Press, Perkins School for the Blind, Howe Innovation
★ MIT LMP
★ Hypertherm

54. Thank you!
Questions?