- Thanks for the introduction, and I'm Jaeyoung Park,
from the Korean Institute of Science and Technology,
which is a national lab in South Korea.
Today, I'm presenting a study which investigated
the effect of providing two different types
of haptic feedback to the fingertip and the palm
on the perceived site of a large virtual object.
On this slide is the overviews of my talk today,
and as you can see, like motivation,
the description of the system,
and experimental evaluation, and finally, results.
The motivation of the study is
to design a better haptic interface
to feel and interact with the virtual object better.
We took a note on the haptic interfaces,
which are typically lighter and smaller
than more widely used quality type for 3-D interfaces.
And on top of the slide, you can see
the four fitting type interfaces, the haptic interfaces,
which provide full feedback to a users interact
with the virtual object.
And at the bottom, you can see
the continued fingertip display which are widely studied
in the haptic and robotics society in these days,
and it stimulate the user's skin directly,
as he or she grabs and interacts with the virtual object.
And one common feature of most of the haptic interface
is that they provide haptic feedback to only fingertips.
But sometimes, when you're grabbing
and interacting with an object,
this picture is a large object,
our hand touches the object, not only
with the fingertip, but also with the palm.
So a haptic innovate designer might consider
to provide a haptic fitting to the palm, as well as
to fingertips to provide more belief
and realistic sensation of grabbing an object.
So in addition, we raised a more practical question,
which is would and how does additional cutaneous feedback
to the palm affect the perception of large virtual object?
To answer this question, we built a haptic system that can
provide two different types of haptic feedback varieties.
One is, first feed is the fingertip,
and another is the extended feedback to the palm.
For the fingertip kinesthetic for feedback,
we built channels, maybe that small.
And you can see the VIVE Tracker for the position input
and the world potentiometer to link rotation and the
servomotor for versatility to fingertip.
And as you can see, the structure has
decided to be fitted for various finger size
and the two for the motor,
use a Servomotor, but as you know,
the typical servomotors work with the pushing control,
so it's not back-drivable
and it hinders the natural interaction,
and the application of control rendering,
and so we took away the controllable
so it was like a dismal, rotary encoder.
And the palm cutaneous feedback interface
consists of four palm tactile feeding modules,
which is in the blue circle.
And some of you might wonder why and how
we decided the number and location
of the tactile feedback modules, the small ones.
Actually, the awareness was kinda a simple story which
and we ended up to deciding a smaller number
on the palm feedback module would be suffice.
When activated, the servomotor plate at the bottom
pushes your skin down, I think you'll see in a bit later.
And you can see in the video, there's some
cylindrical bumpy surfaces to run and ensure linear motion.
So haptic system, I guess the overview of the haptic system.
We have the haptic interface and the sensory data
is sent to the iOS system and DAQ board is sent
to the rendering to calculate the amount
of tactile stimulating and is fed back
to the haptic interfaces.
So for the haptic rendering, we first need to
estimate hand posture, and so, we begin with the
position tracker, and we'd get the transfer matrices
for the orientation and its translation global coordinates.
And they'll be the same for all the joints and at the end,
we end up getting the transformation matrix
for the artificial interphalangeal joints
and its positional orientation.
Given the position of the tracker or wrist position,
and the upper joint, we can estimate
the rotation angle finger joints
with the inverse kinematics.
But we still don't know how
the rotation angle in the upper joints.
It's well known that the rotation angle of the DIP and PIP
are quite depend on each other.
We took just one of the models.
It's a lot of study on the conducting, so...
Given the hand posture now, we can just move to the
collision detection to calculate
the amount of detect stimuli, so.
For the sake of competition, we are usually rather
sparse collider horizon because
we are dealing with a large object.
The locator in the contact areas of the fingertip
and the subareas of the palm and the connotation
is conducting two faces conventionally used for
a full face with a wider, larger, surrounding sphere,
and if there's a collision detected in the broad face,
it is moved to the narrow phase collision.
So once the collision detected for the narrow
phase collision, the calculation of collision factor
is just a linear interpolation of them,
and if you can see in the video, as you can see
in the animation, the dismal height was quite well
and it changes quite continuously,
so a user can feel for a natural changing of forces.
Given the collision vector, as calculated
in the previous five year, calculates in torque
or the amount of just plane for the palm
is fitted module quite straightforward.
The contact forces is calculated and followed, follows the
spring model, as conventionally used in haptic rendering
and the amount of force is just the cross product
of the disagreements and the contact force.
For the point, it's most straightforward because it's
just proportional to the collision,
the size of collision vector.
So, on this video is the haptic system in action.
And you can see the device maps well, and the
hand posture has estimated here, and there should
be some force feedback, and cutaneous feedback to the palm.
And here's a kid interacting with the virtual object.
So, coming back to our initial research question,
we wanted to see whether the additional cutaneous
feedback to the palm would be resulting
in some very real discrimination,
or their perception of the virtual object.
To see that, our experiment we ponder experiment paradigm
which is comparing the perception
of virtual size under two conditions.
The one condition, there is fingertip
and palm feedback, and in another,
there will be only fingertip feedback available.
So, we took the one-interval two-alternative
forced choice experiment paradigm,
which even should compare the Weber fraction
for the three experiment conditions.
So if the Weber fraction for the finger plus palm
feedback condition is lower than that
on the fingertip condition, we win.
So the experiment's condition of the essay's
planned previous privacy, and for P and F condition,
in which should represent of course fingertip palm feedback
and fingertip condition, respectively.
And the virtual object was a sphere.
It was like a calculation
of the co-interaction in the reference field.
It was 10 centimeters and they were comparison stimuli
from the field and radii was 2.5 and 15 centimeters.
Therefore, the full experiment run and showed in which
we considered ten trials and the experiment procedure
followed the data of the very typical yes/no experiment.
The number of subjects was 12, and on each trial,
a user was asked to approach a certain point
and grab a portion of what virtual object was not visible.
So there was only half a field of available
and the subject could not see even his or her hand
as you can see in the photo at the bottom.
Some white noise would play on the headphones to
block any possible audio cue from the haptic interfaces.
And here, as you can see, the F plus P condition
Weber fraction was significantly lower than the F condition.
So, good for us.
And on the right side, we also estimated the Weber fraction
for palm feedback which was not actually measuring
in our experiment, but here we just assume some optimal
sensory integration model, so it might not be true,
but the results show, I just wanted to show you
as a reference，though, the Weber fraction
for two different types of fields was
quite comparable theoretically.
And this slide.
We also derived the pressure to weight
contribution of this feedback, this type of feedback
on the perception of the objects is already embarrassing
that the weight for the palm was higher than the fingertip,
but that does not necessarily mean that a user can
feel the approach of the object only with the palm
because it'll be hitting it and slapping it, so,
as I said, I assumed the optimal sensory integration
which has also shown independence to different types
of queue, but we know it's not because as they
put it in the F plus P condition, it's using also the
fingertips so just in the reference for you,
and the mean collision depth and the mean trial times
are shown at the bottom slide, and on the right side,
you can see that the trial time was longer for F plus P
condition, meaning that participants took longer time
to put the experiment when the palm speed was available.
So one possible explanation could be,
people took longer to processing or using time
when more information was available.
So conclusion was, when the feedback from palm available,
people could feel the virtual object better.
In our future work, in the present study, we compare
the procession of virtual object's size, given the fingertip
and the palm, but as many of you already noticed here,
we haven't checked the effect
of another type of haptic field.
It would be cutaneous feedback at the fingertip.
Could be a control location or it could be
just pressure, something else,
or just rotational torque, but we are planning
to investigate the effect
of the cutaneous feedback at the fingertips.
And as I briefly mentioned in the previous slide,
we did not actually measure the Weber fraction.
There was only cutaneous feedback from the palm available,
so I'm pretty sure it'd be higher than the other condition,
but anyway we need some quantitative data, in the future
we will definitely need to work on it and this was worked
by KIST Institute program, and that's it.
Thanks for listening.
(applause)
- [Speaker] Great!
So we have some time for questions, so, I guess
I'll let Dan start it off.
- [Dan] Hi, Dan Ashbrook, University of Copenhagen.
I'm curious if there's any effect
of the tightening of the glove.
So you're pushing on the glove and on the hand
at the same time, so you'd get a sensation all over
the hand I guess from the glove being tightened?
- Yeah see, I think you've got a difficult question.
So when I asked the participant about what did they
felt about the tightening, they said it was not
so perceptible, but since we did not the actual measuring,
with that kind of subjective rating,
I think we can just investigate
the fact later in future work.
- [Dan] So I'm also curious if you have thoughts on
how you might miniaturize this technology, because your
surveys look a little bit--
- Oh yes.
Of course you should start because
a little bit larger I think because the size
of the more recent change of the design.
So we are thinking about using a different type of
actuator, like a SMA and the same ML, we also see
the F usually could also be used as air pressure,
but we thought of using it, but there's a trickiness
in controlling the displacement, so, but we are actually
working with this in SMA so probably, and hopefully,
we're gonna try and do as the professionals do, which
contain the feedback module and some
of the best type of the actuator.
- [Dan] Thanks.
- [Speaker] Great!
So I have a question, so I'm wondering if you
could talk a little bit more about the study.
I think it's a really exciting result showing sort of,
you know, I think, especially in terms
of haptic feedback for people with visual impairments
and other things, we know that people use their whole hand
to really do these haptic exploratory procedures.
And so my question about the study is kind of pertaining
to the size differences between these objects,
and I'm wondering if you could talk a little bit more
about sort of our proprioceptive acuity in terms of
joint angles, and whether or not you think,
basically, I guess my question ends up being that, you know,
the feedback that you're giving to the palm, is sort of
force feedback, or pressure input feedback,
and I wonder if that's just easier
for people to basically tell discriminate
between these two versus sort
of global angle of like hand pose?
I don't know if you have any thoughts about that.
- Yes, thanks for the question.
This is why we are planning to conduct another experiment.
To be honest, I did not actually ask the participant
how they feel better with the palm feedback.
For my case, the reason why I wanted to try
to conduct another experiment, is the only with the video
on the local palm feedback, we can get a glimpse
of the shape but the size, but they are not as crispy
or as discreet as the force feedback.
Could be better with the extended feeling
at the fingertips, that is why we are trying
to get planning to conduct,
to actually determine regarding these questions.
- [Speaker] Yeah, yeah, definitely.
I look forward to that study.
So I'll ask the next speaker to come up,
but I have one more question while they're setting up.
I think really exciting work
about giving this palm feedback.
I'm wondering if you could talk a little bit,
we know a lot from kind of tactile feedback on the fingertip
like contact location and also sort
of angle of incidents matters a lot.
Obviously, our tactile spacial acuity
of our palm is much lower like in the centimeter range,
but do you think things like contact angle
and contact location matters as much in the palm region?
Or is it just sort of because we have this lower
spacial acuity kind of just pressure anywhere,
in these kind of large regions is enough
to give you meaningful feedback?
- Oh yes.
I think, to answer your question, we need
to conduct experiments, so I think there would
be no clear definite answer but from my experience,
just managing on the palm, the sensitivity is a lot lower
than that of a fingertip, so we end up having
the normal pressure down there.
I think it's very interesting to give like an orientation.
Of course, we desire to have
more tactile information like contact location.
But my answer is, as a researcher,
I think we need experiment data.
- [Speaker] Great, I look forward to it.
Wonderful, thanks so much.
Okay, lets give...