PORTLAND, Ore. —Waterloo Labs, a team of engineers inside National Instruments Corp. (NI), Wednesday (Nov. 3) unveiled the LabView source code to "EyeMario," which demonstrates how video gamers can use their eyes to control Nintendo gaming consoles.
Marrying NI software with electrically isolated data converters from Analog Devices Inc. (ADI), enabled the EyeMario reference design, which NI is making available as a free download. Besides gaming, EyeMario will also being adapted to use in the treatment for amblyopia (lazy eye) as well as to empower people who have lost the use of their hands.
"Medically, these measurements are not new, but our use of them for control is," said Chris Culver, an analog hardware engineer and Waterloo Labs team member. "The movie Beowulf used this technique to track the eye movement of actors, which was mapped onto its computer generated characters."
The technique works because the eyeball is polarized like a dipole, with the more negative polarity at the back of the eye where the optic nerve exits. By placing adhesive electrodes around the eye, then measuring its electrical polarity as it rotates to different orientations, the specific on-screen objects that the eye is aiming as can be deduced. Beta testers in Waterloo Labs have been able to control the direction and actions of the on-screen Mario character in Nintendo's games completely hands free. Watch a flash video demonstrating EyeMario.
Electrodes surround the eye of Doug Farrell, product marketing engineer at National Instruments, as he demonstrates the game Mario controlled by eye movements.
To safely monitor the delicate dipole-like polarity of the eye—without endangering the user—NI (Austin, Texas) had to use ADI's iCoupler technology, which converts the analog input signal into a 1-bit data stream using sigma-delta modulation. Even an electrical short on the circuit board cannot shock the user, because iCoupler uses on-chip transformers that isolate the sensor's inputs.
"Our data converter is fully isolated—a part of our iCoupler technology," said Steve Hinderliter, converter marketing director at ADI (Norwood, Mass.). "This completely isolates the gamer from the 110 volts power supply in the game console."
The EyeMario prototype used the AD8221 precision instrumentation amplifier to pass the signal from the user's eye to the AD7401analog-to-digital converter on a daughter board with a reconfigurable field-programmable gate array (FPGA). NIs LabView app then measured the eye's orientation, as it moves, and translates that into the signals recognized by the Nintendo game console.