FEATURES:                                                        p30 02 Jun
01
 #45  Simply sensational
          Sometimes you need a push in the right direction. Mark Schrope
          tries on a second skin that tells you exactly what to do

 Mark Schrope (Mark Schrope is a science writer based in Florida)

 FOR ANGUS RUPERT, the inspiration came during an impulsive nude
skydive. 'As I was making that jump I realised that there's a lot
of information that can be conveyed through the sense of touch,'
he says. As a result, Rupert, a flight surgeon for NASA and the
US Navy, has produced the world's first tactile flight suit. He
hopes it will help avoid the myriad accidents caused by pilots
becoming disoriented. It's an astonishing innovation. Simply plug
your suit into the cockpit and you can fly a jet fighter
blindfold.

 The suit is just one of a growing number of applications being
developed to exploit our response to touch. Researchers have
shown that the skin's hotline to the brain - which is what allows
you to swat a biting mosquito without stopping to think about
your aim - can open up a range of possibilities. As well as
saving pilots and their aircraft, this instinctive reaction to
touch could soon be keeping you from crashing the family car, and
guiding you to your destination. Eventually, the skin may provide
a substitute for other, faulty senses, helping blind people to
find their way around and allowing deaf people to hear.

 Tapping the potential of the skin has taken nearly three decades
of research. The first indication that the skin had so much to
offer came in 1972 when two Princeton University psychologists
stumbled across the discovery that the sense of touch could be
tricked in the same way that an optical illusion can fool the
eyes. Frank Geldard and Carl Sherrick were trying to figure out
how the brain interprets the sensation of something tapping on
your skin. They built an armband that held three vibrators made
from headphone speakers spaced down the forearm. The vibrators
were wired up to a signal generator, which was meant to give one
tap at each vibrator. But the wiring was wrong. Instead of a
single tap at each vibrator Geldard received five quick taps at
the wrist, then five more in the middle of his forearm, then five
more on his elbow. But he felt something completely different. He
could feel taps at points between the vibrators, and reported the
sensation of a tiny rabbit hopping up his arm. The illusion
became known as the 'cutaneous rabbit'.

 Geldard and Sherrick spent years exploring this and other aspects
of touch. But they remained largely alone in the field, and
progress has been slow. Worldwide, only about 100 people are
researching touch, compared with thousands looking into sight and
hearing. Roger Cholewiak, who now leads Geldard and Sherrick's
lab at Princeton, hopes that the tactile flight suit - and the
other emerging applications of touch - will change that.

 For the past five years, Cholewiak has been helping Rupert with
the development and trials of the suit at the Naval Air Station
at Pensacola, Florida. Cholewiak's expertise has helped Rupert
understand how the vibrators - also known as tactors - should be
arranged and triggered for maximum effect.

 Initially, they experimented with headphone speakers and pager
motors, but the prototype flight suit now uses pneumatic tactors
driven by an air pulse sent down a thin tube. These give a more
powerful vibration than the electrically driven vibrators, and
are less hazardous than plugging a pilot into an electrical
source. They are also much lighter - a crucial factor in
aviation.

 The suit has 32 pneumatic tactors, each about 1.5 centimetres in
diameter and a few millimetres thick. They are arranged all
around the torso, with a couple of centimetres between each
tactor. According to Cholewiak, this is about as close as they
can usefully be. 'The skin doesn't work well with high-density
vibrations,' he says.

 The tactors are driven by a small motor that pumps the bursts of
air according to the electronic output of the cockpit
instruments. In this way, the pilot can receive tactile
information on the aircraft's altitude, pitch, roll and airspeed.
But its main job is to tell up from down. 'Most of the pilots who
died in Desert Storm died because they didn't know which way was
up,' Cholewiak says. Thirty per cent of civil air crashes -
including, investigators believe, the one that killed John F.
Kennedy Jnr - have been attributed to spatial disorientation.

 Knowing where the ground is involves complex and, most
importantly, continuous inputs from our senses. Normally we use
our eyes and our vestibular system - the fluid-filled organs of
the inner ear that give us our sense of balance and orientation.
But in certain situations, these inputs can be misleading: pilots
can be convinced that they are level when in fact they are
plummeting towards the ground or - even more deceptive - the sea.

 Of course there are instruments in modern planes that give
information about orientation. But to read them requires
attention, something in short supply when you lose control in a
momentary burst of turbulence, or are flying a plane low over
bumpy terrain while dodging enemy fire. It doesn't even have to
be a stressful situation for things to go wrong. Hovering a
helicopter, for example, is an inherently difficult task.
Imperceptible movements that go unnoticed by the eyes, the
vestibular system and cockpit instruments can eventually lead to
disaster. When US President Jimmy Carter sent a mission in to
rescue American hostages from Iran in 1980, a hovering helicopter
scuppered the mission - and possibly Carter's chances of winning
a second term - by drifting slowly sideways into a troop carrier.

 Given a tactile suit to wear, however, even someone with no
cockpit experience can keep a hovering helicopter stock-still.
There's no need to interpret the information from cockpit
instruments: responding correctly to the suit's pulses and
vibrations is entirely natural. 'We've tried to make the tactile
display as intuitive as possible,' Cholewiak says.

 So, as the helicopter tilts forward, strong vibrations in the
front of the suit practically force you to pull the stick back.
Drifting to one side gives a vibration on one side of the suit.
Roll to the right, and the vibrations move from your waist
towards your armpit. Raise the nose too much, and there are
vibrations at the back of your neck. Your instinctive response to
each of these stimuli is the right one: every automatic response
corrects for unintentional movement.
Spine tingling

 The system is so effective at delivering information from the
cockpit's instruments that it allows military pilots to fly
blindfold after just a few minutes' training. They can even loop
the loop and know exactly when they ought to level out - during a
backward loop, the tactile suits send a quiver up a pilot's
spine, over the shoulders and then down the front to keep them
oriented. The suits can also warn pilots of approaching enemies:
a tap in the appropriate place on the body gives an instinctive
understanding of exactly which direction that enemy plane is
approaching from.

 Richard Healing, director of the US Navy's Office of Safety and
Survivability, is impressed by the suit's power. 'My sense is
that it's going to be a very valuable tool,' he says. If all goes
well, Healing believes that a tactile display could become
standard equipment in some planes within 5 years.

 Other applications of tactile suits are also on their way.
Military divers are trying out their own version of tactile
sensors that will enable them to navigate and communicate in
pitch-black seas. And tactile displays are even making their way
into space. Hong Tan, an engineering researcher at Purdue
University in Indiana, leads a research group that has already
tested tactile displays on board NASA's 'vomit comet', a plane
that flies in an arcing trajectory to give about thirty seconds
of microgravity. Eventually, Tan hopes to have tactile displays
incorporated into the suits worn by NASA astronauts. This would
help deal with the disorientation experienced on space walks.

 But Tan's other work, which she started at the Massachusetts
Institute for Technology's Media Lab, will have more
down-to-earth applications. Nissan and Honda are helping Tan's
team at Purdue to develop tactile displays for their cars and
trucks. Such displays could be connected to close-range radar
systems to give a punchy warning to drivers when something is too
close. If a child runs out in front of the car, for instance, or
you just get too close to the car in front at high speed, you
could get a sharp tap on the chest from a tactor within your
seatbelt. If something is too close to the side of the car, the
tap would be to that side, perhaps from a tactor on one side of
the lapbelt. A similar system could warn truckers reversing blind
that they are about to hit something. Tan's research has shown
that reaction times can be halved when tactile information
replaces straight visual stimuli - an improvement that could save
lives.

 Tan has also used the cutaneous rabbit to make in-car navigation
systems safer. An array of tactors - modified Walkman headphone
speakers - mounted in the seat back can create the illusion of a
line moving across the driver's back in any direction, telling
them when and which way to turn. Like the tactile flight suit,
this can be used without training: it's entirely instinctive.
'You don't have to think about left or right,' Tan says. 'The
signal is already mapped to the body's coordinate system.'

 Using the rabbit illusion also means that you need less hardware:
there are nine tactors in the seat back, yet people trying it out
report the sensation of up to four times as many taps as were
actually sent. The rabbit builds in redundancy. If one of the
tactors fails, the others can take up its job.

 Tan's research will even benefit people who don't drive. She is
linking a tactile belt to a GPS satellite navigation system, and
using the belt's vibrations to guide a blind person to their
destination. These could replace navigation systems that rely on
beeps or synthesised speech, which can be dangerous if they
divert attention from sounds such as approaching traffic. A
vibration system would also be less conspicuous.

 A further goal of tactile research is to help people with hearing
problems, especially those that develop in childhood. Kimbrough
Oller of the University of Maine in Orono believes a young
child's brain could be trained and reorganised to receive sound
through the skin. 'The neurological plan is not hard-wired and
fixed early in life,' he says. Charlotte Reed, a speech and
hearing researcher at the Massachusetts Institute of Technology
in Cambridge believes that Oller's idea might be accomplished
using a relatively simple display with only a few tactors.
Varying types and textures of vibrations - such as changing
frequencies - might allow complex information to be transmitted
by simple equipment. This would keep the cost of tactile hearing
down, making it perhaps tens of thousands of dollars cheaper than
cochlear implants.
Touch tones

 No one has yet developed such versatile tactors, though, and the
limited market for such devices doesn't help speed research
along. However, the latest industry to seize on the potential of
touch might make a big impact on tactor technology. Jan van Erp,
an experimental psychologist working at the TNO Human Factors
Research Institute in Soesterberg, the Netherlands, wants to
develop vibrators that will put vibrating 'tunes' on mobile
phones. He and his team have been experimenting to see how easily
people recognise the rhythm of a song in tactile form.
Eventually, your phone might be programmed to rattle a tacky
tactile love song when your partner calls, and the sombre touch
of the 'Death March' for calls from the office. Stephen Furner,
senior technology manager at BtexaCT near Ipswich in Suffolk, is
excited by van Erp's trials. 'I'm deeply interested,' he says. 'I
think he's come up with a good idea.' Furner predicts that phones
with tactile display options will be available within the next
five years.

 Perhaps by that time, we'll all be wearing smart clothes studded
with built-in vibrators discreetly spread all over the body. So
there will actually be another option for programming the
personalised tones of the tactile telephone. You might decide you
want a call from the boss to tap you insistently and repeatedly
on the shoulder, for instance. Or maybe you'll reserve that
setting for when your other half calls.

For more science news see http://www.newscientist.com


____________________________________________________________
Copyright 2001 New Scientist, Reed Business Information


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