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We can't go far in this class without giving exact
definition of what I mean by haptic.
Now there isn't just one definition that
the community uses.
But this is the one I'd like you to think of for this
class, because it's very general.
Haptic just mean an adjective that is of or relating to the
sense of touch.
It's not a made up word.
It has a Greek root, which means to grasp or to touch.
And nowadays, haptic is very much associated with haptic
technology, that is the ability to create technology
that generates a sense of touch in users.
But when people refer to haptics research, it's
possible they could be referring to human haptics,
the human sense of touch, or haptic technology.
It's nice to think about haptics in two different
categories.
One is the cutaneous haptic sense, that is having to do
with the skin.
This includes temperature, texture, slip,
vibration, and force.
And here, we're talking about low level forces that have to
do with the kind of forces you can just feel on your skin.
On the other hand, you have kinesthesia.
The kinesthetic haptic sense has to do with more gross
movement and forces.
For example, the location and configuration of your body
parts in space, knowing when your body is moving, how much
force you're applying to the environment, or how much force
it's applying to you.
And these are larger scale forces that you might feel in
your muscles or your joints, as well as measuring
compliance of the environment, in terms of gross force
displacement relationships.
It's definitely true that most activities, such as pouring
water into cup from a pitcher, involve both senses and
sometimes even on the same hand.
But all of these together comprise the haptic sense and
dealing with the sense of touch.
And they're very important for enabling the motor control
system, that is our ability to move in the world, both to
coordinate movement as well as to enable perception.
One way to motivate haptics is to think about what life would
be like without touch.
People often compare haptics to vision.
In fact, a good way to even think about the word haptics
is haptics is to touch as optics is to vision.
And so they often think that because vision is so
predominant and we focus on it so much that touch is perhaps
not as important as vision.
I would beg to differ, because I have a few examples, for
what life would be like without touch, to try to
convince you that lack of sense of touch could
potentially be even more difficult than
life without vision.
On the cutaneous side, so thinking about what happens if
you lost your cutaneous sense, there are some very nice video
online that shows the effects of local
anesthesia on motor skills.
So if you go to YouTube and look up this video, you'll see
a video in which a woman is striking a match, first of
all, in normal circumstance.
Then the skin near her fingertips is anesthetized.
Her muscles are not affected.
Her brain is not affected.
Only the ability of the skin to sense contact with the
environment is affected by this anesthesia.
What happens, you'll see on the video, after she gets
anesthetized is that it becomes very difficult for her
to do even the most simple manipulation tasks.
And it takes her an order of magnitude longer to be able to
strike a match.
Now these days, most human subject experiments don't
involve actually anesthetizing the skin.
But you can experience a little bit about what it's
like to lose your cutaneous sense through cold.
So here is a fuzzy picture--
fuzzy in order to try to demonstrate that you've lost
some of your cutaneous sense--
of someone holding some ice cubes.
Ice cubes are used here because they
make the skin cold.
And when the skin becomes cold, some of the
mechanoreceptors--
which I'll talk about in the human haptics lecture--
which are haptic sensors embedded in the skin, don't
function as they should.
And so that cold will give you a temporary loss of your full
cutaneous sensing capabilities.
If you don't want to put ice cubes in your hand and then
try to manipulate things, you can just recall what it might
have been like for you on a very cold day or perhaps you
were skiing, and you were fumbling when you were trying
to zip up your jacket or button your coat.
You're fumbling not because you've lost your ability to
move, but rather because your cutaneous sense has been
knocked out by the cold, and it becomes difficult for you
to know what is the contact status between your fingers
and the environment.
While people often think that they move awkwardly because
their muscles got cold and they can't control their
movement, it's actually due to the lack of sense of touch,
primarily, that's preventing you from being the sort of
dexterous manipulator that you normally are.
Those are some examples of losing the cutaneous sense.
Loss of kinesthesia, on the other hand, is, in a lot of
ways, more debilitating and very difficult for most people
to experience in normal life.
There's a really interesting BBC documentary about a man
named Ian Waterman, as well as other patients, who have lost
their sense of kinesthesia.
So they have lost their ability to know where their
limbs are in space as well as sense gross forces from the
environment.
So again, if you go to this YouTube video,
here, and watch it.
And you can pause the video now and watch both of
these if you like.
If you look at this video, you'll see some examples of
people who have a great difficulty just moving about
in their environment and accomplishing the activities
of daily living, because they've lost proprioception.
Proprioception is the ability to know where
your body is in space.
And it's an important component of kinesthesia.
Or kinesthesia is an important component of proprioception,
depending on whose definition you use.
In any case, you'll see how difficult life
is for these patients.
One of them, whose name I mentioned
earlier, is Ian Waterman.
And there's a book about him in which he likens living
without proprioception to running a daily marathon,
because it requires so much focus and concentration in
order for him to figure out how to move
his limbs in space.
He has to use vision quite a bit, because he needs to be
able to, essentially--
in robotics, we would call this a visual-servoing.
He has to use only vision information to figure out if
he's moving the hand in the right direction.
So losing your sense of kinesthesia is extremely
debilitating.
Probably the closest that a healthy person can get to
having some loss of kinesthesia is when one of
your limbs falls asleep, because you sat on it wrong.
And temporarily that cuts off blood flow to the limb and
some of the receptors in your muscles and such, which would
give you that sense proprioception and force, can
be temporarily knocked out.
As you know, that's also a very awkward sensation.
Touch, in addition to just being useful, in terms of
interacting with the environment and accomplishing
tasks, is also meaningful.
And this is really important when you consider the design
of haptic devices.
Because you have to remember that, because touch is
meaningful and very personal and you're physically
interacting with someone, there's a very personal and
inherent connection that happens between people and
haptic devices.
Just as some examples, sort of fun examples, which are
basically haptic metaphors of how the sense of touch is
ascribed to meaning in our lives, I just have examples of
these haptic metaphors, like getting a grip.
We talk about massaging an ego or someone
having a magic touch.
We also talk about getting a feel for something or
scratching on the surface.
And these are all physical activities that involve
haptics, but we use them to describe more abstract
concepts and ideas.
You might think about, when you do haptic creations on
your Hapkit, can you actually generate haptic sensations
that invoke any of these meanings or haptic metaphors
for people?
Of course, what this class is mainly about is haptic
technology.
And one of the biggest challenges of haptic
technology is the combination of cutaneous and kinesthetic
information that all comes into play in our natural
haptic interactions.
These are just a few examples of what are, essentially,
haptic devices in my laboratory.
Over here, this picture on the left, is a picture of the
master manipulator of the da Vinci Surgical System, which
is the tele-operated surgical robot.
Now clinical, surgical robots don't
have much haptic feedback.
And we'll talk about this more in the next segment.
But we can provide some haptic feedback, because this master
manipulator does have motors on it.
We also happen to have a force sensor in this picture, which
is sensing the amount of grip force that the user applies.
In any case, this is a very classic, kinesthetic or force
feedback haptic device, because it provides resolved
forces, to the fingertips, through a tool.
Another, very classic haptic device is this one here, which
is the Phantom Premium haptic device.
And what this device does is also provide force
feedback to the user.
And it can provide very high fidelity force feedback, that
is high frequency information and very precise forces.
And my student, Nick, here, is interacting with some virtual
objects that he could feel through that haptic device.
This is also a kinesthetic haptic device.
This last picture here, however, is a combination of
cutaneous and kinesthetic feedback, because it's a
haptic surface, whose mechanical and geometric
properties can change depending on how we control it
with the computer.
So my student, Andrew, is pushing on this device.
Because it has an interesting surface that could be explored
over the skin, in a wide area, as well as even with multiple
fingers, it is a type of cutaneous display.
But because he can also push on it with his fingers and get
force feedback, it's a combination of kinesthetic and
cutaneous information.
There are also a lot of essentially, purely cutaneous
haptic displays.
And one example of a very cutaneous haptic display might
be a Braille display.
So for example, a little Braille display might have a
series of bumps, which can raise up or go down, in order
to display a letter.
Or there are even pin arrays like this,
which can display shapes.
And these are, pretty much, just cutaneous devices,
because they focus on the sensations on the skin and
can't really apply large scale force information.