I visited the Robotics Lab at MIT Friday morning to experience Phantom, a
system built by Prof. Ken Salisbury and his students to provide realistic
tactile feedback. I was truly amazed and absolutely thrilled by the quality
of the tactile experience. Here is a short trip report with a summary of what
this technology could mean for tactile interfaces.
What is Phantom?
Phantom is essentially a point robot with three degrees of freedom. The point
robot is controlled by a set of motors and actuators. Its purpose is to use
the motors and actuators to generate the necessary forces to simulate a
particular tactile experience.
How you experience it:
The business end of the Phantom (the phantom itself is fairly large, including
the motors, the power supply, the large metal frame off which the whole thing
hangs etc) is a gimble. This gimble is connected to the motors by actuators,
and is perfectly counterbalanced.
One can connect either a thimble, a stylus, or a pair of tweezers to this
The entire contraption is controlled by software running on a networked PC.
The software running on the PC can instruct the Phantom to produce the right
forces at the gimble to simulate a particular tactile experience.
The first demo was that of a cube with a ball placed on the floor of the
You were virtually "placed" inside this cube; you could move the thimble
around and feel all the walls of the cube. The tactile experience is amazingly
convincing; in fact it was so convincing that I had to put my other hand out
to make sure that the thimble was not in fact touching a solid surface. (and
indeed it was not).
The feeling of moving the thimble along the walls, of moving along the floor
and encountering the spherical ball, of tracing the circle formed by the
intersection of the ball and the floor of the cube were all being produced by
the motors generating the appropriate forces.
Other demonstrations included using a pair of tweezers to grab and lift a
flexible meshlike floor surface, feeling around an asteroid, a torus etc.
The system is capable of reading the description of a polygonal surface from a
file and generate a simulation where you can feel the object.
This system is very very exciting. Using the stylus and tweezer, the level of
tactile feedback I got was about twice what one gets with a cane that has a
good tip. Also, the Phantom's ability to convey texture convincingly is
I think this system has enormous potential for developing tactile interfaces.
Possible application scenarios include:
a) Access to lab work. For instance this is a great way to go feeling around
structures of molecules.
b) As a teaching aid in conveying concepts of solid geometry, higher
dimensional surfaces etc.
c) General tactile interfaces e.g. a tactile interface to a kiosk. You could
envision the Phantom simulating the presence of a button so that a blind user
can locate the various buttons as they appear and disappear on a kiosk.
d) And much much more.
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