CN1776572A - Computer Human-Computer Interaction Method Based on Steady-state Visual Evoked Brain Waves - Google Patents

Abstract

The invention belongs to neuro engineering in biomedical engineering. The method includes following steps: placing brain electrode on scalp of testee; using blinker light in different frequency to stimulate testee; making scalp of testee generate brain wave in same frequency and harmonic component; through amplification, brain wave is converted to digital signal, which is sent to computer; computer analyzes and detects main frequency component; based on coincidence relation list between frequency of brain wave and mouse action or control command, the method sends mouse action or control command corresponding to flash concentrated by testee so as to realize interactive interface between human brain-computer. The invention can help handicapped person to use computer, or normal person in situation of not convenient to use hand to operate computer, for example astronaut in airship or space capsule.

Description

Computer Human-Computer Interaction Method Based on Steady-state Visual Evoked Brain Waves

technical field

The technical invention belongs to the technical field of neural engineering in biomedical engineering.

Background technique

Studies on human brain nerves and EEG science have shown and confirmed that flickering of light of a certain frequency (5-50 times per second) or visual stimulation of movement can induce the same frequency and its harmonics in EEG. Wave components of electrical signals. According to this important physiological feature, the EEG signals of several frequency visual stimuli are extracted, and after encoding and combination, various or complex control electrical signals can be generated.

Brain-Computer Interface (BCI) is a research hotspot in the fields of neural engineering, rehabilitation engineering, and biomedical engineering in recent years. Its starting point is to provide a direct communication channel between the brain and the outside world, instead of relying on the traditional way of interaction through body movements. According to the aforementioned principle, the use of visual evoked potential (Visual Evoked Potential, VEP) EEG signals is a way to achieve this goal.

The powerful calculation, control and communication functions of computers are well known. The operation of the current computer is mainly realized through the interaction of manual operation of the keyboard, mouse and display screen. The computer interactive control method based on the brain-computer interface technology uses EEG signals to replace the physical keyboard and mouse operations of the limbs to realize the human brain-computer interaction interface. This human-computer interaction method can not only help the disabled to use the computer, but also can be used in occasions where it is inconvenient for normal people to operate the computer by hand (such as astronauts in spaceships or space capsules).

Contents of the invention

The present invention designs a computer human-computer interaction method based on steady-state visually induced EEG.

The present invention is characterized in that the method comprises the following steps in sequence:

Step 1. Install the EEG electrode on the occipital prominence of the subject's scalp (see Figure 2), install the reference electrode on the ear, and ground the ground electrode;

Step 2 Use the flickering icon on the side of the computer screen as a flickering light source with different frequencies. The flickering light emitted by the light source stimulates the subjects. The flickering frequency of each light source corresponds to a control signal channel in the computer, or an action of the mouse Command, or direct control signal, the flickering frequency of various light sources is different, and the flickering frequency is selected between 5 and 50 Hz;

Step 3. When the subject focuses on a light source with a flickering frequency in step 2, brain waves with the same frequency as the light source and its harmonic components can be induced on the scalp;

Step 4: After the EEG electrodes in Step 1 collect the EEG induced by the steady-state visual stimulation, the EEG is sent to the computer through the amplifier and the analog/digital converter in turn through the USB or other general-purpose input ports. The control signal input terminal of the computer is converted into the control command of the computer mouse or keyboard

Step 41 detects the main frequency components from the EEG signals input into the computer;

Step 42 Find out the type of mouse or keyboard action according to the detected main frequency components and the set correspondence table between EEG frequency and mouse or keyboard action, and output the corresponding mouse or keyboard action.

Experiments show that this method can effectively control the movement and command operation of the computer mouse with brain waves, and the highest information transmission rate can reach 40 bits/minute, and the average can reach 25 bits/minute.

The feature of this method is to break through the traditional computer human-computer interaction method, extract the EEG induced by human vision, and convert the information of brain electrical activity into control electrical signals, thereby realizing the operation of the computer, or the control of electronic control equipment and devices. etc. control and operation. The system and device have great application significance in many fields, not only can help the disabled to use the computer, but also can be used in occasions where it is inconvenient for normal people to operate the computer by hand (such as astronauts in spaceships or space cabins).

Description of drawings

Fig. 1 is a program flow diagram of the present invention.

Figure 2. Location map of EEG electrodes.

Figure 3 shows icons with different blinking frequencies around the perimeter of a computer screen.

Figure 4 Example of correspondence between screen icons and mouse actions.

Detailed ways

Realize the control example to computer mouse with this method, can realize through the following steps:

(1) 8 different icons are generated around the computer screen, and their flickering frequencies are respectively 8-15 Hz. Each icon corresponds to a control signal channel, or an action command of the mouse, or a direct control signal (see accompanying drawing 3, accompanying drawing 4);

(2) Install the EEG electrodes on the subject's scalp at the position of the occipital prominence (O1, O2 or nearby positions in the attached drawing 2), thereby collecting the subject's EEG signals and passing them through the universal brain After the digital-to-analog conversion of the electric amplifier, it is sent to the computer through the USB port;

(3) Using general-purpose fast Fourier transform or other spectral analysis methods to detect the main frequency component f in the visually evoked EEG;

(4) According to the detected frequency f and the corresponding relationship table between EEG frequency and mouse action (see accompanying drawing 4), the computer performs mouse movement and command operation accordingly. Realize the control and application of the computer, such as typing, drawing and browsing the web;

(5) The setting of the icon 8 "exit key" in the accompanying drawing 4 allows the subject to choose to exit the computer program of the present invention and return to the normal computer operation mode. Can be used to opt out of control when controlling external devices.

Claims (3)

1. based on the computer man-machine interacting method of steady-state vision induced brain wave, it is characterized in that described method contains following steps successively:

Step 1 is installed in the position of subject's scalp occipital protuberance to electrode for encephalograms, reference electrode is positioned on ear, ground-electrode ground connection;

Flashing icon on the step 2 usefulness computer screen limit is as the flasher of different frequency, the passage of scintillation light that this light source sends stimulates the subject, the flicker frequency correspondence of every kind of light source a control signal passage in the computing machine, an or action command of mouse, or direct control signal, the flicker frequency of various light sources has nothing in common with each other, and its flicker frequency is chosen between 5～50 hertz;

When step 3 is absorbed in the light source of a kind of flicker frequency in the step 2 as the subject, on scalp, just can induce brain wave with this light source same frequency and harmonic components thereof;

Electrode for encephalograms in step 4 step 1 collects after this stable state vision stimulates the brain electricity electric wave that is brought out, this brain electricity electric wave is passed through amplifier, A/D converter successively, send into the signal input end of described computing machine by USB or other general input port, change into the control command of computer mouse or keyboard

Step 41 detects the main frequency composition by the EEG signals of input computing machine;

Step 42 is found the action classification of mouse or keyboard according to the brain wave frequency of detected main frequency composition and setting and the mapping table of mouse or keyboard action, exports corresponding mouse or keyboard action.

2. the computer man-machine interacting method based on steady-state vision induced brain wave according to claim 1, the flasher that it is characterized in that described different frequency are the icons of the different frequency flicker of computer screen periphery.

3. the computer man-machine interacting method based on steady-state vision induced brain wave according to claim 1 is characterized in that the described control signal of step 4. directly exported by the output port of described computing machine, is used to control other peripheral devices.

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