[info] newscientist: more on levitation-based haptic interface

[Alejandro Dubrovsky]

(
http://technology.newscientist.com/article/dn13410-maglev-joystick-gives-better-feedback.html
old movie here.
http://www.youtube.com/watch?v=isu7r3Ywqp0
)

Levitating joystick improves computer feedback
Movie Camera

 * 17:52 04 March 2008
 * NewScientist.com news service
 * Jason Palmer

A computer controller levitated by magnets provides a new way to
physically experience virtual objects.

The "maglev" system has benefits over more mechanical haptic controllers
– computer interfaces that stimulate the user's sense of touch – and its
inventors are now working to commercialising the technology.

Haptic technology has uses ranging from remote medical breast checks and
exploring distant lands, to recreating the feel of fabrics.

But most haptic interfaces to date rely upon gloves or robotic arms to
provide feedback to a user. The complex mechanics involved increases
weight and friction that can make it difficult to provide a natural
feel.
Super bowl

To solve that, Ralph Hollis and colleagues at Carnegie Mellon
University, Pittsburgh, US, developed a haptic device with just one
moving part (see video, top right).

A bowl with electromagnets concealed below its base contains a
levitating bar that is grasped by a user and can be moved in any
direction. The magnets exert forces on the bar to simulate the
resistance of a weight, or a surface's resistance or friction. LEDs on
the bar's underside feed back its position to light sensors in the bowl.

This approach has "huge potential", says Anthony Steed, a haptics
researcher at University College London, UK. "This system gets rid of
the mechanical linkages that are a major constraint on most haptic
devices."
Six degrees of freedom

The maglev interface can exert enough force to make objects feel
reassuringly solid, says Hollis, resisting as much as 40 newtons of
force before it shifts even a millimetre.

That's enough to feel the same as a hard surface and better than most
existing interfaces, he says. "Current devices feel very mushy, so it's
hard to simulate a hard surface.”

The device can track movements of the bar as small as two microns, a
fiftieth the width of a human hair. “That's important for feeling very
subtle effects of friction and texture," says Hollis.

And it can exert and respond to all six degrees of freedom of movement –
moving along or rotating about each of the three dimensions of space
(forward/backwards, left/right, up/down).
'Totally different'

Stephen Brewster, of the Interactive Systems Group at the University of
Glasgow, says the maglev approach is totally different from existing
systems.

"It offers things that other devices just can't do – the high forces,
low friction, low inertia, and six degrees of freedom."

After working on a series of prototypes since 1997, Hollis has started a
company called Butterfly Haptics to market the technology. The first six
second-generation versions of the device will soon be shipped for
testing to a consortium of several US and Canadian universities.

The system will be showcased at the IEEE Symposium on Haptic Interfaces
for Virtual Environments and Teleoperator Systems, which opens on 13
March.