Human-Computer Interface (HCI) has become an important area of research
and development for the disabled. A portable wireless eye
movementcontrolled Human-Computer Interface which can be used for the
disabled who have motor paralysis and who cannot speak in multiple
applications (such as communication aid and smart home applications) is
described here.
This Interface consists of four major parts: (1) surface electrodes, (2) a
twochannel amplifier, (3) a laptop (or a micro-processor), and (4) a ZigBee
wireless module. Horizontal and vertical Electro-Oculography (EOG) signals
are measured using five surface electrodes placed on the head.
The vertical electrodes are placed about 1.0 cm above the right eyebrow and
2.0 cm below the lower lid of the right eye, the horizontal electrodes are
placed 2.0 cm lateral to the each side of outer canthi and the last electrode is
placed on user's forehead to serve as a ground. The two-channel amplifier is
comprised of instrumentation amplifiers, band-pass filters and shift circuits.
The EOG signals are sampled at the rate of 250Hz and then sent to a laptop or
a micro-processor for signal processing which is based on the method of
mathematical morphology to recognize the direction of eye movements and
voluntary eye blink. The ZigBee wireless communication technology, which is
proved to be reliable, low -power and cost-efficient, is used in the portable
interface.
The subjects can control the wireless device or move a cursor over a screen
by using this interface. The delay of this interface is less than 0.5s and errors
are very limited. This interface provides a flexible method for the disabled to
improve the life quality.
