[INAUDIBLE] I'm Chi Wang from National Taiwan University,
and she is Shuo-wen Hsu from National Chiao Tung University
Taiwan.
We are glad to be here to present our work, Masque,
[INAUDIBLE] skin stretch feedback on face
with head-mounted display.
Head-mounted displays have been proven
effective in providing users with immersive visual and audio
experiences in virtual reality.
To further enrich the immersive experience,
numerous researchers have worked on hefty feedback on HMD.
[INAUDIBLE] used by [INAUDIBLE] actuator
distributed in three concentric ellipses
around the head for intuitive haptic guidance
through moving techno cues.
And [INAUDIBLE] is embedded with tactile displays
on HMD facial interface through suction.
Also, [INAUDIBLE] continuous normal pressure onto face
to simulate water pressure or continuous pressure
like boxing game.
[INAUDIBLE] element on HMD giving heat or cold on face.
However, skin stretch as hefty feedback on face
still remains to be explored.
When normal pressure is provided on skin texture,
there will be friction when texture moves.
And skin underneath moves along with the texture because
of friction, creating skin deformation,
therefore causing skin stretch feedback.
Skin stress can provide different levels of stimuli
through stretching distance and also
give different notifications through
different stretching direction.
When a shear force is provided to the skin,
it causes lateral skin deformation
and creates skin stress feedback.
Such feedback is often used for enhancing
the experience of virtual object interaction
or directional guidance.
[INAUDIBLE] proposed using [INAUDIBLE] for skin stretches.
When one grabs a virtual object, skin stretch feedback
there is applied to grasped fingers who simulate the weight
and inertia of objects.
Meanwhile, the research on the right
shows that, through different skin displacement,
user would perceived different stiffness.
In this work, we propose Masque integrating
an array of six skin stretch modules on HTC VIVE Pro
to produce skin stress feedback on human face.
We use Masque to conduct two gender studies regarding
stretching distance and angle.
Also, according to study results,
we created three occasions to demonstrate
the capability of Masque.
The [INAUDIBLE] was placed on facial skin.
Actuating the tactors causes lateral skin stretch,
which deliver rich haptic information to a user.
To generously stretch in different intensity
and direction on human face through HMD,
we created a prototype that is able to perform
to a degree of freedom skin stretch,
and every actuator can be freely actuated
without colliding with any others.
In order to perform to a degree of freedom of movement,
we need to give models crowning wheels
to actuate x and y direction respectively.
A third tactor for [INAUDIBLE] with 30 millimeters in diameter
and is covered with 3 millimeter thick silicon pad
to ensure the comfort of users.
Also, we use 3D printing to [INAUDIBLE]
for motors and the best to perfect fit HMD.
In the informal exploratory study,
we explored the user's preference
which is related to the acceptance of physical comfort
when using the detector.
We use convex [INAUDIBLE] and concave in 10,
20, 30 millimeter in diameter [INAUDIBLE]
respectively to conduct the study.
We let participants use the detector to stretch
their facial skin without limiting
in location and direction of stretching distance.
Then we let participants respond with preference rating from 1
to 7 using continuous scale.
The result shows that the scores for the contact
shift [INAUDIBLE] with larger size
are significantly rated higher than the other two.
This is interesting, as previous works usually [INAUDIBLE]
threat of convex shift for the [INAUDIBLE] on fingertips.
Participants report that the concave shift can better
contact facial skin [INAUDIBLE] movement
and cause more clear perception of skin stretches.
They also report that larger size [INAUDIBLE]
results in content area, which can
create more easily perceived skin stretch feedback.
To reduce [INAUDIBLE] cost by module,
we created two ways to balance the whole device.
One is saline grounded.
We used saline grounded pulleys to hang a bag of lead
on the other side.
Another is body grounded.
The lead is added on the backside of HMD
to balance the device.
The sheer factors of masque cover the facial skin
surrounding the eyes and nose.
Therefore, we also conducted a study
on evaluating physical comfort of masque.
We invested what is mixed mask stretching distance
within 15 millimeter.
That is considered physically acceptable by participants.
Participants aged from 20 to 27 used [INAUDIBLE] panel
photodetectors in virtual reality.
And participants can manipulate it with a mouse and keyboard
to report the maximum acceptable distance for each vector
in four fundamental direction.
The results showed that within the 50 millimeter [INAUDIBLE]
max [INAUDIBLE] masque stretching distance,
the average of acceptable stretching distance
is 14.85 millimeter.
Two participants report maximum distance shorter
than 14 millimeters.
They reported that when stretching over too much,
my fragile cheeks were squeezed, which slightly
interfered with my breathing.
Their feedback informs us that future prototyping should also
consider the facial anatomy of individuals.
Considering that facial anatomy might affect sensation,
we also conducted two [INAUDIBLE] study
on stretching distance and angle with masque.
It can help us design skin stretch
patterns using VR applications.
One up, two down staircase method
is applied in both of the studies.
We assume that the scene sensitive on the symmetrical
sample points are similar.
There are three locations with two stretching
direction factorial design.
And two participants were recruited,
and their studies are run under a random order.
We press pressure sensor [INAUDIBLE] each detector
and asked the participant to adjust the [INAUDIBLE] of HMD
until the [INAUDIBLE] HMD was highly
stable yet comfortable to wear.
The average value is approximately 2.5 newtons.
On the left is how [INAUDIBLE] works in distance training
study.
The right is the interface that participants see in VR.
We provide three stimuli, then we
ask participants to select the one that is
different from the other two.
This resource suggests that the change in stretch distance
must be at least 24.6% higher or lower than the current stretch
distance to enable people to perceive a difference.
And multiple levels of stretch feedback
can be created by masque.
Also, we did another study regarding discrimination
threshold for stretching angle.
The average discrimination threshold
of stretching angles across [INAUDIBLE] is 22.69 degrees,
and the highest [INAUDIBLE] value is 42 degrees.
The results suggest that participant could at least
differentiate [INAUDIBLE] skin stretch direction
on their face.
And next, [INAUDIBLE] will introduce demo application
and the result of masque.
Hi.
I'm [INAUDIBLE],, and I will present the rest of our work.
According to previous researches that
have proven skin stretch is effective in simulating
certain stimuli along with the data we get from the studies,
we build three applications to demonstrate masque.
They are motorcycle racing, snowball fight,
and museum guidance.
In the motorcycle racing, masque can simulate weight, shake,
inertia, and normal force from helmet on user's face.
All factors are actuated downward
to simulate the heaviness of the helmet.
Also, the user receives constant up and down
skin stretches on bumpy roads, simulating the shakes
from the helmet.
In response to the direction of the drift, [INAUDIBLE]
stretch in the opposite direction,
which creates a sensation where the helmet is
pulled upon by inertia force.
When the user passes through an acceleration board
on the racetrack, [INAUDIBLE] stretch outward from the eyes,
simulating a constant wind pressure on the face.
In snowball fight, masque stimulates
graze and freezing on face.
If the user barely avoids the attack,
[INAUDIBLE] generates a short term skin stretch
to the eye corners, stimulating the sensation of a graze
from a snowball.
If the user's eye gets hit, all [INAUDIBLE]
constantly stretch inward, creating a restriction
regarding opening the eye.
For museum guidance, mask provides
directional information through different stretch direction.
[INAUDIBLE] created skin stretch profiles for to the left,
to the right, moving forward, and looking up.
The user can select a desired artifact
and move toward the location of the artifact
by following the directional cues by mask.
A simple algorithm was implemented
for finding the shortest path from the user's
current position to the target.
Masque generates skin stretch profiles
according to the directions of that path
and the distance between the user and the destination.
To ensure that the skin stretch feedback generated by masque
is a valuable haptic addition to HMDs,
we conducted a user evaluation study for the applications.
This study is designed to measure
the user's subjective feedback on mask in comparison
to users without haptic feedback.
Participants completed a questionnaire
asking for agreement ratings on their feelings in regard
to realism and enjoyment for each skin stretch
profiles using a continuous seven point Likert scale.
For example, in snowball fight, the participants
were asked how realistic when your face hit by the snow
and how enjoyable the stimulus is in the fight.
For the motorcycle racing game, the results
indicates that all of the skin stretch profiles
received significantly higher scores
than no haptic condition.
Three participants reported that it's
like wearing an actual helmet.
However, there were also two participants
who gave lower scores to their inertia and shake profile,
as they thought the force illusion is less
realistic if there is no haptic feedback on the human body
as well.
For the snowball fight game, the freezing profile
received marginally significant higher scores,
and the graze profile received significantly higher scores.
Half of the participants rated higher scores
for the freezing profile, as they considered
that the profiles can simulate the interference
fields from the snow.
However, the other half of the participants
reported the freezing profile is less realistic,
as our system should provide thermal and vibration
feedback after being attacked.
The also reported that the freezing and the grace profiles
shocked me and made me tense.
And therefore, I became more aggressive and more competitive
in this game.
Since the stretching profile in museum guidance
is directional information, realism
is not rated in this part.
And without haptic feedback, participants
need to look at the location of artifacts on a mini map
nearby that display the position of the user and the path
to a target destination.
Although all of the participants could
distinguish the directions well and arrive at destinations
without the help of visual clues,
they also felt that the mini map should not
be removed in the haptic condition.
Four participants suggesting that long term skin stretches
made them feel annoyed.
On the other hand, other participants
considered that the skin stretches
helped them to pay attention to the virtual environment instead
of the mini map, making them feel more
immersed during the guidance.
In this paper, we investigated the skin stretch
on distance and angle.
For future work, we will take more factors
into consideration--
for example, stretch facial skin during body movement
to check if discrimination threshold will be affected.
In addition, [INAUDIBLE] prototype
can only perform linear skin stretch.
And we will further investigate the impact
from different skin displacement,
such as twisting skin.
And several works have done researches
in combining multiple haptic feedback.
In the future, we will study on skin stretch combining
with other output.
There are also other works regarding
force perception model in weight or stiffness on hand.
And therefore, we will investigate force perception
model on human face.
And since human feature varies across individuals
and is not completely symmetric, we
hope the hardware can be customized or adjustable
so as to feed individuals.
And last, currently works under power supply.
However, [INAUDIBLE] VR wearables are the trend.
So we want to make masque powered
by battery in the future.
And the contribution of this work
is the concept of creating lateral skin displacement
by physically stretching the contact
skin and the results of user studies
that investigate the capabilities of skin stretch,
the implementation of mask, the proof of concept prototype,
and a set of applications that demonstrate the concept,
and finally, the results of a preliminary user
evaluation on this new haptic HMD prototype.
We also shared our 3D model on GitHub.
So feel free to scan the QR code for the 3D models.
And thanks for listening.
We're happy to take your questions.
Thanks very much.
We have time for a question.
[INAUDIBLE]
Did you have to do anything in terms of the prototype
to manage sweat on the face, especially the forehead?
Sweat-- uh, would you please say it again, sir?
Did you need to adjust for how easy it
was to adhere to people's skin such as if they were sweating?
[INAUDIBLE] on your face [INAUDIBLE] the sweat.
Well, during the study, we didn't
observe that circumstances.
So maybe we'll improve that in the future.
But during the study, we didn't observe that circumstances.
Yes.
Did you saw with the bike example
that adding haptics according to acceleration,
does it helps with reducing motion sickness?
Emotion?
Motion sickness.
Ah, motion sickness.
[INAUDIBLE]
No.
A little bit?
Well, uh, because their body move
with the direction they toward--
so during the study, they didn't report
that there was motion sickness, not even in the motorcycle
racing.
OK, thank you.
Let's thank our speakers again.
[INAUDIBLE]