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Haptic, from the Greek αφ? (Haphe), means pertaining to the sense of touch
(or possibly from the Greek word haptesthai meaning “contact” or “touch”).
Haptic technology refers to technology which interfaces the user via the sense
of touch by applying forces, vibrations and/or motions to the user. This
mechanical stimulation is used to create haptic virtual objects. This emerging
technology promises to have wide reaching applications. In some fields, it
already has. For example, haptic technology has made it possible to investigate
in detail how the human sense of touch works, by allowing the creation of
carefully-controlled haptic virtual objects. These objects are used to
systematically probe human haptic capabilities. This is very difficult to
achieve otherwise. These new research tools contribute to our understanding of
how touch and its underlying brain functions work (See References below).
Although haptic devices are capable of measuring bulk or reactive forces that
are applied by the user it should not to be confused with touch or tactile
sensors that measure the pressure or force exerted by the user to the interface.
History
One of the earliest forms of haptic devices is used in large modern aircraft
that use servo systems to operate control systems. Such systems tend to be
"one-way" in that forces applied aerodynamically to the control surfaces are not
perceived at the controls, with the missing normal forces simulated with springs
and weights. In earlier, lighter aircraft without servo systems, as the aircraft
approached a stall the aerodynamic buffeting was felt in the pilot's controls, a
useful warning to the pilot of a dangerous flight condition. This control shake
is not felt when servo control systems are used. To replace this missing clue,
the angle of attack is measured, and when it approaches the critical stall point
a "stick shaker" (an unbalanced rotating mass) is engaged, simulating the
effects of a simpler control system. This is known as haptic feedback or force
feedback.
Teleoperators and simulators
Teleoperators are remote controlled robotic tools, and when contact forces are
reproduced to the operator, it is called "haptic teleoperation". The first
electrically actuated teleoperators were built in the 1950's at the Argonne
National Lab, USA, by Dr. Raymond C. Goertz, to remotely handle radioactive
substances. Since then, the use of "force feedback" has become more widespread
in all kinds of teleoperators such as underwater exploration devices controlled
from a remote location.
In 1988 researchers at Cybernet Systems first developed devices that generated
arbitrary forces from computer models or simulations in lieu of actual physical
slave devices. When such devices are simulated using a computer (as they are in
operator training devices) it is useful to provide the force feedback that would
be felt in actual operations. Since the objects being manipulated do not exist
in a physical sense, the forces are generated using haptic (force generating)
operator controls. Data representing touch sensations may be saved or played
back using such haptic technologies. Cybernet licensed its force feedback
patents to Immersion Corporation in 1998 and Immersion licensed Logitech,
Microsoft, Sony and others to manufacture Force Feedback joysticks, wheels, and
othere devices worldwide.
Haptic simulators are currently used in medical simulators and flight simulators
for pilot training (2004).
Games
Some low-end haptic devices are already common in the form game controllers, in
particular of joysticks and steering wheels. At first, such features and/or
devices used to be optional components (like the Nintendo 64 controller's Rumble
Pak). Now many of the newer generation console controllers and some joysticks
feature built in devices. Many have believed these controllers to be providing
force feedback when in reality true force feedback involves the feedback of a
resisting force to the user. An example of this feature would be the simulated
automobile steering wheels that are programmed to provide a "feel" of the road.
As the user makes a turn or accelerates, the steering wheel responds by
resisting turns or slipping out of control. Another concept of force feedback
was that of the ability to change the temperature of the controlling device.
This would prove especially efficient for prolonged usage of the device.
However, due to the high cost of such a technology (not to mention the power
drainage of such a component) the closest many manufacturers have come to
realizing this concept has been to install air holes or small fans into the
device to provide the user's hands with ventilation while operating the device.
Haptics in virtual reality
Haptics is gaining widespread acceptance as a key part of Virtual Reality
systems, adding the sense of touch to previously visual-only solutions. Most of
these solutions use stylus-based haptic rendering, where the user interfaces to
the virtual world via a tool or stylus, giving a form of interaction that is
computationally realistic on today's hardware
Research
Some research has been done into simulating the different kinds of tactition by
means of high-speed vibrations or other stimuli. One device of this type uses a
pad array of pins, where the pins vibrate to simulate a surface being touched.
While this does not have a realistic feel, it does provide useful feedback,
allowing discrimination between various shapes, textures, and resiliencies.
Medicine
Various haptic interfaces for medical simulation may prove especially useful for
training of minimally invasive procedures (laparoscopy/interventional radiology)
and remote surgery using teleoperators. In the future, expert surgeons may work
from a central workstation, performing operations in various locations, with
machine setup and patient preparation performed by local nursing staff. Rather
than traveling to an operating room, the surgeon instead becomes a telepresence.
A particular advantage of this type of work is that the surgeon can perform many
more operations of a similar type, and with less fatigue. It is well documented
that a surgeon who performs more procedures of a given kind will have
statistically better outcomes for his patients.
In ophthalmology, "haptic" refers to a supporting spring, two of which hold an
artificial lens within the lens capsule (after surgical removal of cataracts).
A 'Virtual Haptic Back' (VHB) is being successfully integrated in the curriculum
of students at the Ohio University College of Osteopathic Medicine. Research
indicates that VHB is a significant teaching aid in palpatory diagnosis
(detection of medical problems via touch). The VHB simulates the contour and
compliance (reciprocal of stiffness) properties of human backs, which are
palpated with two haptic interfaces (SensAble Technologies, PHANToM 3.0).
Literature
The use of haptic devices in entertainment appeared in the 1932 futurist fiction
book Brave New World by Aldous Huxley. The author described a future
entertainment theater where the arm rests of the seats had positions for the
hands to rest that gave haptic stimulation. The programs exhibited were of an
erotic nature and rather than "the movies" these theaters and shows were called
"the feelies". Haptic devices, including self-propelled haptics, feature
prominently in Vernor Vinge's 2006 novel Rainbows End.
Remote sexual relations
One envisioned use of haptics is for "teledildonics". Some sex toys are now
available which can be computer controlled; normally this comes in the form of
an online movie or Web site which sends commands to the toy at scripted moments.
Robotics
The Shadow Dextrous Robot Hand uses the sense of touch, pressure, and position
to reproduce the human grip in all its strength, delicacy, and complexity. The
SDRH was first developed by Richard Greenhill and his team of engineers in
Islington, London, as part of The Shadow Project, (now known as the Shadow Robot
Company) an ongoing research and development program whose goal is to complete
the first convincing humanoid. An early prototype can be seen in NASA's
collection of humanoid robots, or robonauts. The Dextrous Hand has haptic
sensors embedded in every joint and in every finger pad which relay information
to a central computer for processing and analysis. Carnegie Mellon University in
Pennsylvania and Bielefeld University in Germany in particular have found The
Dextrous Hand is an invaluable tool in progressing our understanding of haptic
awareness and are currently involved (2006) in research with wide ranging
implications.
Arts
Touching is not limited to a feeling, but it allows interactivity in real-time
with virtual objects. Thus haptics are commonly used in virtual arts, such as
sound synthesis or graphic design/animation. The haptic device allows the artist
to have direct contact with a virtual instrument which is able to produce
real-time sound or images. We can quote the physical modelling synthesis which
is an efficient modelling theory to implement cross-play interaction between
sound, image, and physical objects. For instance, the simulation of a violin
string produces real-time vibrations of this string under the pressure and
expressivity of the bow (haptic device) held by the artist.
Design
Designers and modellers may use high-degree of freedom input devices which give
touch feedback relating to the "surface" they are sculpting or creating,
allowing faster and more natural workflow than with traditional methods.
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