In the Realm of Illusion
Touch might well be the most basic of human senses, its complex messages easily understood and analyzed even by the crib and pacifier set. But what sets it apart from other senses is its dual communication conduit, allowing us to send information by the same route through which we perceive it. In other words, those same fingers that acknowledge your receipt of a handshake send data on their own.
In one project a few years back, Peter J. Berkelman and Ralph L. Hollis began stretching reality in all sorts of bizarre ways. Not only could humans using their device touch things that weren't there, but they could reach into a three-dimensional landscape and, guided by the images appearing on a computer screen, move those objects around.
This was all done with a device built at the lab based on Lorentz force magnetic levitation (Lorenz force is the force exerted on a charged particle in an electromagnetic field). The design depended upon a magnetic tool levitated or suspended over a surface by means of electromagnetic coils.
To understand the design of this maglev device, imagine a mixing bowl with a joystick bar in the middle. Now imagine that the knob of the joystick floats barely above the stick, with six degrees of freedom. Coils, magnet assemblies, and sensor assemblies fill the basin, while a rubber ring makes the top comfortable for a human operator to rest a wrist. This whole business is set in the top of a desk-high metal box that holds the power supplies, amplifiers, and control processors.
Looking at objects on a computer screen, a human being could take hold of the levitated tool and try to manipulate the objects as they were displayed. Force-feedback data from the tool itself provided tactile information for holding, turning, and moving the virtual objects.
What might not be obvious from this description is that this model offered a marvel of economy, replacing the bulk of previous systems with an input device that had only one moving part. Holding the toolor perhaps pushing at it with a fingerthe operator could "feel" the cube seen on the computer screen: edges, corners, ridges, and flat surfaces. With practice, operators could use the feedback data to maneuver a virtual peg into a virtual hole with unnerving reliability.
Notice something here: An operator could receive tactile impressions of a virtual object projected on a screen. In other words, our perception of reality was starting to be seriously messed around with here.