Eye-brain interface (EBI) system and method for controlling same
Methods and systems for calibrating an eye-brain interface (EBI) system controlled on the basis of eye movements and brain waves according to one embodiment of the present invention are disclosed. A method includes: providing an eye-brain calibration (EBC) interface for calibrating eye movements and brain waves simultaneously, wherein the EBC interface includes a visual object and instructs a user to gaze into the visual object in a particular cognitive state; acquiring eye movements and brain waves of the user for the visual object included in the EBC interface; mapping the visual object and eye movements of the user; and mapping the particular cognitive state instructed to the user and brain waves of the user.
1. A method for calibrating eye tracking and brain waves, the method comprising:
providing sequentially and/or alternately a first visual object with a first cognitive state and a second visual object with a second cognitive state;
obtaining gaze positions and brain waves of user on the first visual object and the second visual object;
calibrating the gaze positions with the brain waves, and the first and second cognitive states with the gaze positions and brain waves,
wherein the first cognitive state is a cognitive state of attention, and the second cognitive state is a cognitive state of rest.
2. The method of claim 1 , further comprising:
adjusting flickering frequencies of the first visual object and the second visual object.
3. The method of claim 2 , further comprising:
obtaining first raw data on a brain wave in the first cognitive state, and second raw data on a brain wave in the second cognitive state;
converting frequencies of the first raw data and the second raw data; and
setting a criterion for classifying the first and second cognitive states based on the frequency characteristics of the frequency-converted first raw data and the second raw data,
wherein the setting the criterion comprises:
extracting a frequency amplitude for each of frequency bands in a predetermined range from the frequency-converted first raw data and second raw data;
obtaining a Fisher's ratio for each of the frequency bands using the extracted frequency amplitude;
selecting a first frequency band having a highest Fisher's ratio and a second frequency band having a second highest Fisher's ratio; and
setting the first and second frequency bands as the criteria for classifying the first and second cognitive states.
4. The method of claim 3 , wherein the Fisher's ratio is calculated based on an average and a variance of the frequency amplitudes in the frequency-converted first raw data and an average and a variance of the frequency amplitudes in the frequency-converted second raw data.
5. The method of claim 2 , wherein the frequency band in the predetermined range corresponds to δ-wave band, θ-wave band, α-wave band or β-wave band of a brain wave.
6. The method of claim 2 , wherein the adjusting a flickering frequencies comprises:
adjusting the flickering frequencies of the first visual object and the second visual object to approximately 8 to 13 Hz to induce the brain wave to an alpha wave range, or adjusting the flickering frequencies of the first visual object and the second visual object to approximately 13 to 30 Hz to induce the brain wave to a beta wave range.
7. The method of claim 1 , further comprising:
obtaining an iris image from the user's eye; and coding the iris image.
8. The method of claim 7 , wherein the coding the iris image comprises:
dividing the obtained iris image into a plurality of images;
arranging the plurality of images in one direction; and
converting the images arranged in the one direction into a single two-dimensional image.
9. A host device controlled based on eye tracking and brain waves, comprising:
a display configured to display an image;
and
a processor configured to
control the display and provide a first visual object with a first cognitive state and a second visual object with a second cognitive state,
request and receive gaze positions and brain waves of a user on the first visual object and the second visual object,
and calibrate the gaze positions with the brain waves and the first and second cognitive states with the gaze positions and brain waves,
wherein the first cognitive state is a cognitive state of attention, and the second cognitive state is a cognitive state of rest.
10. The host device of claim 9 , wherein the processor is further configured to
adjust a flickering frequencies of the first visual object and the second visual object;
obtain first raw data on a brain wave in the first cognitive state, and second raw data on a brain wave in the second cognitive state,
convert frequencies of the first raw data and the second raw data,
extract a frequency amplitude for each of frequency bands in a predetermined range from the frequency-converted first raw data and second raw data,
obtain a Fisher's ratio for each of the frequency bands using the extracted frequency amplitude,
select a first frequency band having a highest Fisher's ratio and a second frequency band having a second highest Fisher's ratio, and
set the first and second frequency bands as the criteria for classifying the first and second cognitive states.
11. The host device of claim 10 , wherein the processor is further configured to obtain the brain waves of the user in real-time and classifies the brain waves of the user obtained in real-time according to the criteria in real-time.