A NEW type of tactile feedback system that stretches your skin rather than
pressing into it could help drivers keep their eyes on the road. It could turn a
car鈥檚 steering wheel into a touchy-feely instrument panel that transmits
dashboard data to a driver through their fingertips.
鈥淗aptic鈥� interfaces such as tactile-feedback gloves are already used to
convey information to people using virtual reality systems. But Vincent Hayward
at the Centre for Intelligent Machines at McGill University in Montreal, Canada,
believes the devices that exploit our skin鈥檚 sensitivity to stretching could
have far wider uses. 鈥淭hey could be used anywhere a liquid crystal display is
currently used,鈥� he claims.
鈥淭here is some evidence to suggest that stretch is more important than we
previously realised,鈥� says Hayward. He says Australian researchers have shown
that people may have an extra neural receptor relating to stretch that other
primates lack. 鈥淭his may explain why monkeys have different grasping strategies
to us,鈥� he says.
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Hayward鈥檚 experimental tactile display consists of a flat array of
millimetre-thick vertical pins
(see Graphic). Each pin is mounted on a pair of
piezoelectric rods coated with electrodes. Applying a voltage to the electrodes
makes the piezoelectric rods flex, which tilts the pin by up to 50 micrometres
in each direction. Pins in alternate rows move either left to right or front to
back.
鈥淭he motion of each individual pin is minuscule, of the order of a few
micrometres, and yet the resulting sensation is very noticeable,鈥� says
Hayward.
Hayward believes that this stretch sensitivity could ultimately be more
important than pressure information and has already shown that normal sensations
which contain combined pressure and stretch can be produced using skin stretch
alone.
His hope now is to experiment with the display to try to elicit different
textural sensations. By doing this he believes it may be possible to 鈥渞everse
engineer鈥� the stimulation needed to mimic a range of surface textures鈥攕uch
as leather, plastic or velvet. He is also working on refining the display to see
whether varying the shape of the pin tips may heighten the user鈥檚 sensation.