WEARABLE HEAD-MOUNTED, GLASS-STYLE COMPUTING DEVICES WITH EOG ACQUISITION AND ANALYSIS FOR HUMAN-COMPUTER INTERFACES

• US 20150126845A1
• Filed: 11/05/2014
• Published: 05/07/2015
• Est. Priority Date: 11/05/2013
• Status: Active Grant

• Current Assignee: The Research Foundation for The State University of New York (State University of New York)
• Original Assignee: The Research Foundation for The State University of New York (State University of New York)
• Inventors: Jin, Zhanpeng, Laszlo, Sarah
• Granted Patent: US 9,955,895 B2
• Time in Patent Office: Days
• US Class Current: 600/383
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/398 Electrooculography [EOG], e.g. detecting nystagmus; Electroretinography [ERG]
• CPC Class Codes: A61B 5/6803 Head-worn items, e.g. helmets, masks, headphones or goggles
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: G02B 2027/014 comprising information/image processing systems
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 2027/0187 slaved to motion of at least a part of the body of the user, e.g. head, eye
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G06F 1/163 Wearable computers, e.g. on a belt
• CPC Class Codes: G06F 3/013 Eye tracking input arrangements G06F3/015 takes precedence
• CPC Class Codes: G06F 3/015 Input arrangements based on nervous system activity detection, e.g. brain waves [EEG] detection, electromyograms [EMG] detection, electrodermal response detection

Abstract

A apparatus for detecting electrooculograph (EOG) signals, comprising: a pair of temple pieces connected to a bridging structure; at least one electrode on each temple piece configured to contact the skin at the temple, and to receive an EOG signal from a proximate orbital socket; a reference electrode displaced from each temple; and a processor configured to process signals from the sensors to detect saccade movements of the eyes. A wavelet-based algorithm permits analysis and coding of the saccade movements.

Claims

1. An apparatus for detecting electrooculograph (EOG) signals, comprising:

a pair of temple pieces connected to a bridging structure;

at least one electrode on each temple piece configured to contact the skin at the temple, and to receive an EOG signal from a proximate orbital socket;

a reference electrode displaced from each temple; and

a processor configured to process signals from the at least one electrode on each temple piece and the reference electrode to detect saccade movements of the eyes.

2. The apparatus according to claim 1, wherein the processor is configured to characterize an amplitude and a sign of an EOG signal.

3. The apparatus according to claim 1, wherein the processor is further configured to characterize a sequence of states of an EOG signal as a single user command selected from a wordbook of valid user commands.

4. The apparatus according to claim 1, wherein the at least one electrode on each temple piece configured to contact the skin at the temple comprises at least two electrodes, configured to determine changes in a vertical and horizontal axis of the EOG signal.

5. The apparatus according to claim 1, wherein the processor is further configured to perform baseline drift compensation by performing a wavelet transform decomposition of the EOG signal to provide wavelet transform coefficients, estimate a baseline drift based on the wavelet transform coefficients, and to compensate the baseline drift based on the estimated baseline drift.

6. The apparatus according to claim 1, wherein the processor is further configured to:

perform an approximated multilevel 1D wavelet decomposition at level nine using Daubechies wavelets on each EOG signal to produce a set of decomposition coefficients;

estimating a drift of the EOG baseline using the decomposition coefficients; and

subtracting the estimated drift of the EOG baseline from each EOG signal.

7. The apparatus according to claim 1, wherein the processor is further configured to implement median filter denoising, having a window sufficiently small to retain short signal pulses associated with eye blinks.

8. The apparatus according to claim 1, wherein the processor is configured to separately analyze movement of right and left eyes separately.

9. The apparatus according to claim 8, wherein the processor is configured to determine consistency of right and left eye saccadic movements.

10. The apparatus according to claim 1, wherein the processor is further configured to:

perform a continuous wavelet transform (CWT) on the EOG signals;

applying a threshold on the coefficients of the CWT transform to segment the EOG signal into periods of saccadic movement and fixation;

filtering saccadic periods based on duration; and

determining a signed saccade amplitude for each filtered period.

11. The apparatus according to claim 1, wherein the processor is further configured to:

perform a Continuous Wavelet Transform (CWT) on the EOG signals s, wherein the CWT first computes continuous 1D wavelet coefficients at scale 20 using a Haar mother wavelet, wherein;

ψ

(t) is the mother wavelet;

12. The apparatus according to claim 1, wherein an amplitude of an EOG signal during a saccade movement is corrected for a change in baseline by subtracting an amplitude of an EOG signal during a time when a saccade is not detected temporally proximate to the saccade movement.

13. A method for detecting electrooculograph (EOG) signals, comprising:

providing a pair of temple pieces connected to a bridging structure to a human or animal, having at least one electrode on each temple piece configured to contact the skin at the temple, and to receive an EOG signal from a proximate orbital socket and a reference electrode displaced from each temple; and

processing electronic signals from the at least one electrode on each temple piece to detect saccade movements of the eyes.

14. The method according to claim 13, wherein said processing comprises determining a baseline EOG signal amplitude during an absence of saccade movements, and determining an amplitude and a sign of an EOG signal during a saccade movement.

15. The method according to claim 14, further comprising characterizing a sequence of a plurality of amplitudes and signs of an EOG signal over a period of time as a single user command selected from a wordbook of valid user commands.

16. The method according to claim 13, wherein the at least one electrode on each temple piece configured to contact the skin at the temple comprises a plurality of electrodes on each temple piece, configured to determine changes in a vertical and horizontal axis of the EOG signal.

17. The method according to claim 13, further comprising:

compensating for a drift of the EOG baseline using decomposition coefficients of a wavelet decomposition on each EOG signal; and

implementing a median filter to denoise the baseline corrected EOG signal, having a window sufficiently small to retain short signal pulses associated with eye blinks.

18. The method according to claim 17, further comprising:

determining, based on coefficients of a continuous wavelet transform of the EOG signals, respective periods of eye saccadic movement and eye fixation;

filtering the periods of eye saccadic movement based on duration to eliminate periods of eye saccadic movement below and above respective lower and upper thresholds; and

determining a signed saccade amplitude for each filtered period.

19. A method for detecting electrooculograph (EOG) signals from eyes of a human or animal, comprising:

providing a pair of temple pieces connected to a bridging structure supported by a nose of the human or animal, having at least one electrode on each temple piece configured to contact the skin at the temple, substantially without contacting an infraorbital facial surface, and to receive an EOG signal from a proximate orbital socket and a reference electrode displaced from each temple;

processing electronic signals from the at least one electrode on each temple piece and the reference electrode to characterize an amplitude and direction of saccadic movements of the eyes and fixation of the eyes; and

interpreting sequences comprising a plurality of characterized amplitudes and directions of saccadic movements of the eyes and fixations of the eyes as a user command.

20. The method according to claim 19, further comprising processing electronic signals from the at least one electrode on each temple piece and the reference electrode to characterize electromyographic signals.