hi everyone my name is Seraphina Yong
and I'm a second year PhD student at the
University of Minnesota. I'm going to be
presenting our work on understanding
both the non-visual and visual needs for
the design affordances of laser cut
models. This work was done with my
collaborators Ruei-Che Chang, Fang-Ying Liao,
Chih-An Tsao, and advised by Professor
Bing-Yu Chen.
In recent years, laser cut objects have
been a key component of the maker
movement, due to their ability to enable
rapid prototyping at a more affordable
cost.
Maker movements such as Do-it-Yourself
Assistive Technology (DIY-AT) have also enabled
people with disabilities to make
artifacts that fulfill their own needs
and engage in the greater maker community.
However, compared to most 3D printed
objects which are usually produced in
one piece, laser cut objects require a
manual assembly step which involves
complex manipulation of small detailed
pieces. This is an overlooked
accessibility barrier for Blind and
Visually Impaired, or BVI individuals who
engage in making and prototyping.
As laser cut assembly can be tedious and
challenging for both BVI and sighted users,
recently emerging systems have been
developed to help facilitate the
assembly process.
Roadkill provides laser cutting plans to
enable fast assembly, and Daedalus
presents a design framework to help BVI
individuals successfully assemble laser
cut models.
However, current solutions to make laser
cut models easier to use tend to work
around existing models, which are still
inaccessible.
Therefore, we conducted an empirical
study to understand how the design of
laser cut models themselves can be made
fundamentally more accessible to both
BVI and sighted users.
Based on the impact laser cut assembly
has on usability and the design process
of laser cut pieces, we conducted a mixed
methods controlled study focusing on the
assembly process to understand: (1) what
strategies both sighted and BVI users
share in common when assembling
laser-cut models, (2) what strategies
they don't share in common, and (3)
which tactile design properties of laser
cut components have positive or negative
influences on assembly.
To assess a representative sample of
current laser cut models, we had seven
sighted and seven BVI participants each
assemble five laser cut models which
represented the most common joint types
and combinations currently used in laser
cutting. This was determined based on a
survey of the Thingiverse online
database that was completed in a prior
work.
After each assembly task, participants
reported their strategies and
self-assessed difficulty for each model.
To ensure comparable data across BVI
and Sighted groups, we included an
assembled reference for each laser cut
model that was only accessible by touch.
Previous work demonstrated that BVI
users need a reference model to complete
laser cut assembly, and the touch
restriction ensured that both sighted and
BVI users would approach the assembly
task with equal reference information.
We employed a variety of quantitative
and qualitative measures in this study. We
measured the time taken to complete
assembling each model, the assembly
accuracy based on the number of accurate
laser-cut joint pairings, participants'
self-reported difficulty rating for each
model,
the distribution of assembly behaviors
across different laser-cut models, as
well as qualitative data from interviews
and video footage.
In this presentation we will focus on
discussing the qualitative findings.
Please see our paper for more details.
We synthesize our main findings from the
labeled activity distributions,
participant interviews, and observations
of video footage. We found strategies
which were common across sighted and BVI
participants, ones that were used
exclusively by sighted participants,
and issues relating to physically
manipulating the model across both
participant groups.
We found that features inherent to
individual laser-cut pieces, such as
aligning edges with the same lengths
together, were used by both BVI and sighted
users.
Both BVI and sighted users mentioned
aligning edges and observing for
protrusion, which would indicate a lack
of edge alignment.
However, many alignment cues were more
visually- and not haptically-salient,
causing sighted users to benefit from
this strategy more often than the BVI
users during assembly.
In one of our laser-cut models, there
were slightly-curved versus flat
alignments of similarly-shaped pieces
that sighted users could tell apart, but
the slight difference was not salient to
BVI users through touch.
We also found that both sighted and BVI
users use clues and shape patterns that
are shared across multiple pieces,
such as symmetrical, unique, and similar
piece shapes to help them figure out how
to assemble the model.
We found an interesting contrast in
strategy where BVI users benefited more
from unique piece shapes which are more
easily distinguished through touch, while
sighted users were confused by them and
preferred to work with similarly-shaped
pieces.
We also identified several
vision-dependent assembly strategies,
such as global observation and inference,
where sighted users visually-assess
multiple pieces to look for joining
clues without touching anything.
For example, sighted users observed contour
continuity across different pieces to
figure out how they would be arranged
together,
and also observed the presence of small
protrusions around piece joints as clues
for assembly direction.
Sighted participants also made use of
piece features that were haptically
inaccessible either due to their global
nature of spanning multiple separate
pieces or the smaller joint details that
are harder to tell by touch.
For example, they used observation of
joint distribution across all pieces to
determine what the adjacent joining
pieces should be, as well as how the
pieces fit into the overall model.
Apart from strategies, we also determined
overall physical features of the laser
cut model that made assembly difficult.
For example, there was a stark contrast
between sighted users' ability to make
inferences and complete assembly using
mid-air comparison,
and BVI users who struggled to stabilize
models that came apart easily.
Data from our activity labeling during
assembly also shows that BVI users spent
significantly more time stabilizing the
assembled model than sighted participants.
We found that both sighted and BVI users
struggled with the fixed order in which
many laser cut models must be assembled,
though this design feature is often to
interlock or stabilize the model itself.
Multiple sighted and BVI participants
recognized this feature without having an
efficient solution for assembly.
We also found that various features of
individual laser-cut joints made using
them highly-inaccessible for BVI
individuals.
For example, small mortise joints are
extremely hard to perceive by touch,
and precise joining angles are difficult
to align and maintain without any visual
feedback.
The struggle was compounded by the lack
of accessible haptic feedback on whether
a joint was completely assembled or not.
In addition to the highly precise
joining angles, the design of laser-cut
joints to have a tight fit caused uneven
haptic feedback during assembly, making
it hard for BVI users to evaluate the
process of their own assembly.
From this work, we found that both sighted
and BVI users share many common
approaches towards assembling and using
laser-cut models.
We found that only sighted users could
access more global and joint-specific
features of laser-cut pieces due to the
extra visual information.
BVI users shared a common difficulty in
physically manipulating small laser cut
pieces, and the joints, which are even
smaller.
And interestingly, we also found that
uniqueness of piece shape was very
helpful for BVI users but contrasted
sighted users' tendency to rely on semantic
inferences.
Based on these findings, we generated
several design implications for more
accessible laser-cut models.
Because BVI users can be particularly
skilled at recognizing and assigning
meaning to distinct shape patterns
perceived through touch,
making individual laser-cut joints more
haptically-distinct can support better
haptic matching of pieces instead of
only visual matching.
Our findings also showed the need for
haptic accessibility in physically
joining laser cut pieces.
Cantilever-based joints, shown in the top
right, can easily be adopted to lower
friction, allow wiggle room during
assembly, and provide clear haptic
feedback to BVI users when a joint locks
in place.
Living hinges are also a cutting method
that can be adapted to help users form
laser-cut models without assembling
joints.
Both BVI and sighted users struggled
with the restricted order of assembly
in most laser cut models, making it a
big issue.
Fixed-order elements of laser cut models
should be made clear to users before the
assembly stage, such as making specific
pieces more perceptually distinct, or
supporting alternative methods of
joining the model in case someone needs
to reassemble.
More general design implications apply
to not only laser-cut models, but also
for any other physical artifact to be
accessible to both BVI and sighted users.
The design of many objects, including
laser-cut models, revolves around
assumptions of knowledge that are
exclusive to sighted people. Without
extra information, it is difficult for
BVI people to access physically
disconnected spatial patterns through
touch, or evaluate information of a scope
that is larger than what can be touched.
We advise future designers to keep these
principles in mind when designing
physical artifacts. Please see our paper
for more complete details of our
findings and discussion.
Thank you for listening!