Researchers at Carnegie Mellon University (CMU) have developed a new haptic interface using magnetic levitation to give computer users the sense of touch. Unlike current haptic systems, this new device doesn't use gloves or robotic arms. It uses 'magnetic levitation and a single moving part to give users a highly realistic experience.' So far, 10 prototypes have been built and some of them will go to Harvard, Stanford, Purdue or Cornell. With this haptic interface, which will take a big chunk of your desk, you will be able to perceive textures and feel hard contacts. But don't expect to use it before several years. Read more...
As you can see above, this maglev haptic device needs some room on a desk. The photo above shows how a user can insert a square peg into a square hole in both real and virtual 6-degree-of-freedom environments. (Credit: CMU's Microdynamic Systems Laboratory). Please read the Psychophysics of Haptic Interaction page for more details and pictures about other experiments.
This research project has been led by Ralph Hollis, research professor in CMU Robotics Institute. Hollis is also a member of the Magnetic Levitation Haptic Consortium, an international group dedicated to increase use of haptic devices in the real world. Here is a link to Hollis project. In December 2007, Hollis founded Butterfly Haptics, LLC to commercialize the technology.
You can see on the left another view of the CMU maglev haptic device. (Credit: CMU, on this page)
What's new with this device? "The system eliminates the bulky links, cables and general mechanical complexity of other haptic devices on the market today in favor of a single lightweight moving part that floats on magnetic fields. At the heart of the maglev haptic interface is a bowl-shaped device called a flotor that is embedded with six coils of wire. Electric current flowing through the coils interacts with powerful permanent magnets underneath, causing the flotor to levitate. A control handle is attached to the flotor."
And how does this device work? "A user moves the handle much like a computer mouse, but in three dimensions with six degrees of freedom -- up/down, side to side, back/forth, yaw, pitch and roll. Optical sensors measure the position and orientation of the flotor, and this information is used to control the position and orientation of a virtual object on the computer display. As this virtual object encounters other virtual surfaces and objects, corresponding signals are transmitted to the flotor’s electrical coils, resulting in haptic feedback to the user."
In "Levitating joystick improves computer feedback," New Scientist provides additional details. "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."
And here are some quotes from Hollis reported by New Scientist. "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."
For more information about these haptic devices, here are two links to technical papers, the papers "Comparison of 3D Haptic Peg-In-Hole Tasks in Real and Virtual Environments" (PDF format, 6 pages, 374 KB) and "Virtual Peg-In-Hole Performance using a 6-DOF Magnetic Levitation Haptic Device: Comparison with Real Forces and with Visual Guidance Alone" (PDF format, 8 pages, 398 KB).
Sources: Carnegie Mellon University news release, March 4, 2008; Jason Palmer, New Scientist, March 4, 2008; and various websites
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