more complex, engineers will have to optimize for a much more diverse set of sensory receptors in the human body that respond to pressure, movement, and temperature changes.

As the range of possible touch-based interfaces expands, developers face a further hurdle in helping users make sense of all the possible permutations of haptic feedback. This lack of a standard “haptic language” may prove one of the most vexing barriers to widespread market acceptance. Whereas most people have by now formed reliable mental models of how certain software interfaces should work—keyboards and mice, touchpads, and touch screens, for example—the ordinary consumer still requires some kind of training to associate a haptic stimulation pattern with a particular meaning, such as the urgency of a phone call or the status of a download on a mobile device.

The prospect of convincing consumers to learn a new haptic language might seem daunting at first, but the good news is that most of us have already learned to rely on haptic feedback in our everyday lives, without ever giving it much thought. “We make judgments based on the firmness of a handshake,” says Ed Colgate, a professor of mechanical engineering at Northwestern University. “We enjoy petting a dog and holding a spouse’s hand. We don’t enjoy getting sticky stuff on our fingers.” Colgate believes that advanced haptics could eventually give rise to a set of widely recognized device behaviors that go well beyond the familiar buzz of cell phones. For now, however, the prospect of a universal haptic language seems a distant goal at best.

“Until we have a reasonably mature approach to providing haptic feedback, it’s hard to imagine something as sophisticated as a haptic language arising,” says Colgate, who believes that success in the marketplace will ultimately hinge on better systems integration, along the lines of what Apple has accomplished with the iPhone. “Today, haptics is thought of as an add-on to the user interface,” says Colgate. “It may enhance usability a little bit, but its value pales in comparison to things you can do with graphics and sound. In many cases, the haptics is so poorly implemented that people turn it off pretty

as haptic devices
grow more complex,
engineers will
have to optimize for
a much more
diverse set of
sensory receptors
in the human body
that respond to
pressure, movement,
and temperature
changes.

quickly. And that’s not to criticize the
developers of haptics—it’s just a tough
problem.”
Many efforts to date have used hap-
tics as a complementary layer to exist-
ing screen-based interfaces. MacLean
argues that haptics should do more
than just embellish an interaction al-
ready taking place on the screen. “A lot
of times you’re using haptics to slap it
on top of a graphical interaction,” she
says. “But there can also be an emotion-
al improvement, a comfort and delight
in using the interface.”
Led by Ph.D. candidate Steve Yo-
hanan, MacLean’s team has built the
Haptic Creature, a device about the
size of a cat that simulates emotional
responses. Covered with touch sensors,
the Haptic Creature creates different
sensations—hot, cold, or stiffening its
“ears” in response to human touch.
The team is exploring possible applica-
tions such as fostering companionship
in older and younger people, or treating
children with anxiety disorders.

MacLean’s team has also developed an experimental device capable of buzzing in 84 different ways. After giving users a couple of months to get familiar with the feedback by way of an immersive game, they found that the process of learning to recognize haptic feedback bore a great deal of similarity to the process of learning a language.

HPC

Students
Build
Green500
Super-
computer

a team of students at the
University of Illinois at
Urbana-Champaign (UIUC)
have built an energy-efficient
supercomputer that appeared
on both the Green500 and
top500 lists. Named in honor
of one of the UIUC campus’s
main thoroughfares, the Green
Street supercomputer placed
third in the Green500 list
of the world’s most energy-
efficient supercomputers,
with a performance of 938
megaflops per watt. It also
placed 403rd in the top500
list, a ranking of the world’s
fastest supercomputers, with a
performance of 33. 6 teraflops.
the Green Street
supercomputer grew out of
an independent study course
led by Bill Gropp, the Bill and
Cynthia Saylor Professor of
Computer Science, and
wen-mei hwu, who holds
the amD Jerry Sanders Chair
of electrical and Computer
engineering. approximately
15 UIUC undergraduate and
graduate students helped
build the supercomputer,
which boosts a cluster of 128
graphics processing units
donated by NVIDIa, and uses
unorthodox supercomputer
building materials, such as
wood and Plexiglas.
the UIUC team hopes to
increase the supercomputer’s
energy efficiency by 10%–20%
with better management of its
message passing interface and
several other key elements.
“You really need to make sure
that the various parts of your
communications path, in
terms of different software
layers and hardware drivers
and components, are all in
tune,” says hwu. “It’s almost
like when you drive a car, you
need to make sure that all these
things are in tune to get the
maximum efficiency.”
the Green Street super-
computer is being used as a
teaching and research tool.