KR101400141B1 - half-field SSVEP based BCI System and motion method Thereof - Google Patents

Abstract

A BCI-based SSVEP system and its operating method are disclosed. The BCI-based SSVEP system includes an EEG sensing electrode unit for attaching to a user's occipital lobe and measuring an EEG signal; A target examining unit including a plurality of visual stimulators arranged between two of the visual target targets and blinking at different frequencies; And a processing unit for classifying and processing the EEG signal output from the EEG sensing electrode unit as the user gazes at each of the targets provided in the target examination unit.

Description

[0001] The present invention relates to an SSVEP-BCI system using a left-right visual path difference,

The present invention relates to a method for acquiring an SSVEP signal without a user's direct visual stimulation, and more particularly, to a patient with a lock-in syndrome requiring BCI technology, thereby reducing the risk of fatigue and epilepsy for a long time, And a SSVEP - BCI system using the left and right visual path differences that can issue multiple commands at a limited frequency through a combination of visual stimulators, and its operation method.

SSVEP (Steady State Visually Evoked Potentials) refers to the same frequency component as the stimulator in the occipital lobe, which is responsible for the visual center of the brain, when the user is gazing at a visual stimulus that blinks at a specific frequency.

BCI (Brain Computer Interface) refers to a system that measures and analyzes signals such as brain conduction and NIR to understand human thoughts and willingness to manipulate external devices and communicate with others.

The SSVEP response can be applied to the BCI system, and SSVEP signals that occur when patients with lock-in syndrome, such as a limb paralysis patient, take a visual stimulus such as a monitor or LED, I can figure out my thoughts.

The problem to be solved by the present invention is that the conventional SSVEP-based BCI can be easily fatigued because the user has to directly look at the stimulator, and in some frequency regions, the risk of epilepsy is increased. There has been a limit to this.

Also, since the frequency range in which the human brain reacts is limited, it has been the cause of lowering the overall accuracy of the system if many frequencies within a limited frequency range can be used simultaneously.

Therefore, the present invention can be applied to patients with lock-in syndrome requiring BCI technology to reduce the risk of fatigue and epilepsy for a long period of time and to use them for a long time, as well as to use a combination of visual stimuli A BCI-based SSVEP system using the left and right visual path differences, and an operation method thereof.

According to an embodiment of the present invention, there is provided a BCI-based SSVEP system using an EEG sensing electrode unit for measuring an EEG signal attached to a user's occipital lobe. A target examining unit comprising a plurality of visual stimulators arranged between two of the visual target targets, the visual stimulating targets being arranged in a plurality of letters and numerals; And a processing unit for classifying and processing the EEG signal output from the EEG sensing electrode unit as the user gazes at each of the targets provided in the target examination unit.

The EEG sensing electrode unit may include one of a dry electrode and a wet electrode.

The processor comprising: a processor; A storage unit in which a plurality of registers for storing EEG signals output from the EEG sensing electrodes are arranged; And a display unit for displaying data output from the storage unit through the processor, wherein the processor is operative to output data stored in the storage unit in accordance with the brain wave signal corresponding to a target that the user has performed, And the storage unit is provided with the same number of registers as the number of the targets.

The EEG sensing electrode unit is characterized in that at least two brain wave electrode sensors are attached to the visual center region of the user in the transverse direction.

And each of the plurality of visual stimulators is an LED light source of a different color.

According to another aspect of the present invention, there is provided a method for operating a BCI-based SSVEP-BIC system according to an embodiment of the present invention includes: a target gazing step of gazing at one of gaze gazing targets arranged in a target gaze unit; Measuring an electroencephalogram signal according to the gaze target at the EEG sensing electrode; A storage step of storing the measured electroencephalogram signal in a registry; Recognizing a pattern by repeating the target viewing step and the storing step by the number of gazing targets arranged in the target gazing unit; And a display step of outputting data corresponding to the target to be examined by the user through the processor and displaying the data after the pattern recognition is completed.

According to the present invention, the SSVEP signal can be acquired and applied to the BCI even if the user does not directly look at the start stimulator.

In addition, by avoiding the direct gaze of the visual stimulator, it is possible to reduce the risk of eye fatigue and epilepsy due to long-term use.

In addition, there is an effect that many targets can be created by using a limited frequency combination.

1 is a block diagram illustrating a BCI-based SSVEP system using right and left visual path differences according to an embodiment of the present invention.
FIG. 2 is an exemplary view showing that the EEG sensing electrode portion of the human occipital region is attached to the O1 and O2 regions.
3 is an illustration of a stimulator that allows a user to make a desired command while stimulating the left and right visual pathways at different frequencies.
4A to 4D are graphs showing examples of EEG signals measured in the O1 and O2 regions of the occipital lobes according to the position of the visual stimulator.
FIG. 5 is a flowchart illustrating an operation method of a BCI-based SSVEP system using the left and right visual path differences shown in FIG.

Specific structural and functional descriptions of embodiments according to the concepts of the present invention disclosed in this specification or application are merely illustrative for the purpose of illustrating embodiments in accordance with the concepts of the present invention, The examples may be embodied in various forms and should not be construed as limited to the embodiments set forth herein or in the application.

Embodiments in accordance with the concepts of the present invention can make various changes and have various forms, so that specific embodiments are illustrated in the drawings and described in detail in this specification or application. It should be understood, however, that the embodiments according to the concepts of the present invention are not intended to be limited to any particular mode of disclosure, but rather all variations, equivalents, and alternatives falling within the spirit and scope of the present invention.

The terms first and / or second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms may be referred to as a first component second component only for the purpose of distinguishing one component from another component, for example without departing from the scope of the right according to the concept of the present invention, The two components can also be named as the first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, .

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises ",or" having ", and the like, are intended to specify the presence of stated features, integers, steps, operations, elements, , Steps, operations, elements, parts, or combinations thereof, as a matter of principle, without departing from the spirit and scope of the invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. Hereinafter, the present invention will be described in more detail with reference to the drawings.

1 is a block diagram illustrating a BCI-based SSVEP system using right and left visual path differences according to an embodiment of the present invention. FIG. 2 is an exemplary view showing that the EEG sensing electrode portion of the human occipital region is attached to the O1 and O2 regions, and FIG. 3 is a diagram showing an example in which a stimulus Fig.

1, the BCI-based SSVEP system using the left and right visual path differences of the present invention includes a (100) EEG sensing electrode unit 140, a target examining unit 110, a processing unit 120, and a display unit 130, .

The EEG sensing electrode unit 140 is attached to a user's occipital lobe and measures a brain wave signal. More specifically, the EEG sensing electrode unit 140 includes a first sensing electrode unit 141 and a second sensing electrode unit 142, The first sensing electrode unit 141 may be a sensing electrode unit that senses an SSVEP signal corresponding to a right line of sight of the user, and the second sensing electrode unit 142 may correspond to a left line of sight The sensing electrode unit sensing the SSVEP signal.

The target gaze unit 110 includes a plurality of gaze target targets arranged in a plurality of characters (e.g., alphabets) and numerals (e.g., Arabic numerals), and is provided between two gaze gazing targets among the gaze gaze targets, A plurality of visual stimulators 111 that are discriminated by frequency are provided.

The processing unit 120 performs a function of classifying and processing the EEG signal output from the EEG sensing electrode unit as the user gazes at each of the gazing targets provided in the target gaze unit 110.

Here, the user directly looks at the number. During the gaze, the SSVEP signal corresponding to the corresponding letter or number is generated according to the blinking frequency of the visual stimulator.

More specifically, the EEG sensing electrode unit may be either a dry electrode or a wet electrode, and each electrode may be a silver-silver chloride (Ag-AgCl) electrode.

The processing unit 120 includes a signal processing unit 121 and a database 122.

The signal processing unit 121 includes an amplification unit, a first filter unit, an A / D converter, and a second filter unit.

The amplifying unit amplifies the EEG signal sensed by the EEG sensing electrode unit.

The first filter unit filters the EEG signal amplified by the amplification unit.

The A / D converter converts the EEG signal, which is an analog signal filtered by the first filter unit, into a digital signal.

The second filter unit performs a function of filtering the EOG digital signal converted through the A / D converter, and outputs the EOG digital signal to the database.

Wherein the amplifying unit includes a first amplifier and a second amplifier, wherein the first amplifier receives and amplifies a first EEG signal measured at the first sensing electrode, and the second amplifier amplifies the first EEG signal measured at the second sensing electrode 2 EEG signal is received and amplified.

Each of the first and second amplifiers is designed to have a high input impedance and a high common mode rejection ratio (CMRR).

The first filter unit may include at least one low pass filter (LPF) that removes a lower frequency band than a band pass region, and at least one high pass filter that removes a higher frequency band than the band pass region. Filter (HPF).

Wherein the second filter unit includes at least one digital low pass filter (DLPF) for removing a frequency band lower than a band pass region, and at least one digital high pass filter (Digital High Pass Filter) (DHPF).

The database 122 includes a plurality of registers (not shown) for storing EEG signals output from the first and second sensing electrodes 141 and 142, respectively.

The display unit 130 functions to display data output from the database through the signal processing unit 121.

Here, the signal processing unit 121 may include a processor, and the processor is operated to output data stored in the database in accordance with the EEG signal corresponding to a target that the user has examined, It is designed to have the same number of registers as the number of targets.

Referring to FIG. 2, the EEG sensing electrode unit 140 of the present invention may be provided in the O1 and O2 regions of the occipital region of a human, and the O1 region and the O2 region may function as a cheek Area.

Referring to FIG. 3, the left and right visual stimulators provided on the left and right sides of the targets blink at a constant frequency and blink at different frequencies.

For example, if you want to issue a "Light Off" command, the user strikes the "Light Off" character instead of the visual stimulator. When the user strikes the letter "Light Off", the user's EEG signal is measured in the O1 and O2 regions of the brain's visual backbone.

The measured signals are received in the processing unit and classified according to the frequency according to the target. The right visual field frequency is detected in the O1 region and the left visual field frequency is detected in the O2 region by the optic crossing.

For example, if the user is looking at the letter "Light Off" and is blinking at 12 Hz in the left visual stimulator and 21 Hz in the right visual stimulator, the frequency of 21 Hz is detected in the user's O1 region and the frequency component of 12 Hz in the O2 region is relatively As shown in FIG.

Through this frequency classification and analysis, the user is able to identify the target he or she is looking at.

4A to 4D are graphs showing examples of EEG signals measured in the O1 and O2 regions of the occipital lobes according to the position of the visual stimulator.

Referring to FIGS. 4A to 4D, there are the results when the user uses the visual stimulator to change the blink frequency of the left and right visual stimulators while gazing at the middle "+" target.

For example, in FIG. 4A, it can be seen that a signal of the left stimulator is generated on the right side of the brain. In FIG. 4B, a signal of the right stimulator is generated on the left side of the brain. In FIGS. 4C and 4D, The visual stimulator flickers at 12 Hz and the right visual stimulator flickers at 18 Hz and 16 Hz, respectively. In this case, the left 12 Hz stimulus appears to be relatively high in the right region of the brain, while the stimulation of 18 Hz and 16 Hz on the right side It can be seen that it is relatively high.

FIG. 5 is a flowchart illustrating an operation method of a BCI-based SSVEP system using the left and right visual path differences shown in FIG.

5, the operation method (S100) of the BCI-based SSVEP system using the right and left visual path differences includes a target gazing step S110, an EEG signal measuring step S120, a storing step S130, Step S140 and display step S150.

The target gazing step (S110) may be a step of gazing on any one of gaze gazing targets arranged in the target gaze section.

The EEG signal measuring step S120 may be a step of measuring an EEG signal according to the gaze target at the EEG sensing electrode unit.

The storing step (S130) may be a step of storing the measured electroencephalogram signal in the registry.

The pattern recognizing step S140 may be a step of recognizing a pattern by repeating the target gazing step S110 to the storing step S130 by the number of gaze gazing targets arranged in the target gaze unit 110. [

After the pattern recognition is completed, the display step S150 may output data corresponding to the target target taken by the user through a processor (not shown) and display the data.

Therefore, according to the present invention, the SSVEP signal can be obtained and applied to the BCI even if the user does not directly look at the start stimulator.

In addition, by avoiding the direct gaze of the visual stimulator, it is possible to reduce the risk of eye fatigue and epilepsy due to long-term use.

In addition, there is an effect that many targets can be created by using a limited frequency combination.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: a system 110: a target-
120: Processing section 121: Signal processing section
122: Database 130: Display
140: EEG sensing electrode part 141: first sensing electrode
142: second sensing electrode

Claims (6)

An EEG sensing electrode attached to a user's occipital lobe to measure an EEG signal;
A target examining unit comprising a plurality of visual stimulators arranged between two of the visual target targets, the visual stimulating targets being arranged in a plurality of letters and numerals;
A processing unit for classifying and processing the EEG signal output from the EEG sensing electrode unit as the user gazes at each of the targets provided in the target examination unit; And
And a display unit for displaying data processed through the processing unit,
Wherein,
A database in which a plurality of registers for storing EEG signals output from the EEG sensing electrodes are arranged; And
And a signal processing unit operable to output data stored in the database in accordance with the EEG signal corresponding to the target of the user,
The database includes:
The same number of registers as the number of targets are stored,
The signal processing unit,
An amplifying unit for amplifying an EEG signal sensed by the EEG sensing electrode unit;
A first filter unit for filtering the amplified EEG signal;
An A / D converter for converting the EEG signal, which is the filtered analog signal, into a digital signal; And
And a second filter unit for filtering the converted digital signal. The SSVEP - BCI system using the right and left visual path differences.
The method according to claim 1,
The EEG sensing electrode unit includes:
Wherein the SSVEP - BCI system comprises either a dry electrode or a wet electrode.
delete The method according to claim 1,
The EEG sensing electrode unit includes:
Wherein at least two electroencephalogram electrode sensors are attached to the visual center region of the user in the transverse direction, and the SSVEP - BCI system using the right and left visual path differences.
The method according to claim 1,
Wherein each of the plurality of visual stimulators comprises:
SSVEP - BCI system using left and right visual path difference, characterized by being LED light sources of different colors.
A target gazing step of gazing at a gaze gazing target of any one of a plurality of gaze gazing targets arranged in a target gaze section;
Measuring an electroencephalogram signal according to the gaze target at the EEG sensing electrode;
A storage step of storing the measured electroencephalogram signal in a registry;
Recognizing a pattern by repeating the target viewing step and the storing step by the number of gazing targets arranged in the target gazing unit; And
And a display step of outputting data corresponding to the target target taken by the user after the pattern recognition is completed through a processor and displaying the data,
Wherein the step of measuring the electroencephalogram signal comprises:
Amplifying an EEG signal sensed by the EEG sensing electrode unit;
Filtering the amplified EEG signal;
Converting the EEG signal, which is the filtered analog signal, into a digital signal; And
And filtering the transformed digital signal,
Wherein the EEG signal is measured through a visual stimulator provided between two of the visual target targets and discriminated at different frequencies.

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