Space-frequency fusion visual stimulation method and system

Abstract

The invention discloses a space-frequency fusion visual stimulation method and system. The method comprises the following steps: S1, selecting a central stimulation target and four adjacent stimulation targets around the central stimulation target; s2, setting an arrangement mode of the stimulation blocks; s3, the two arrangement modes are stimulated in sequence, and the stimulation frequencies of the five stimulation blocks and the corresponding electroencephalogram signal amplitudes are obtained; s4, selecting an arrangement mode in which the number of the stimulation frequencies of the central stimulation target including the stimulation frequencies of the surrounding four adjacent stimulation targets is maximum and the amplitude of the electroencephalogram signals induced by the stimulation frequencies is maximum as an optimal arrangement mode; compared with the prior art, the characteristic of partition backlight space crosstalk is converted into the multi-frequency characteristic advantage, a traditional single signal loudness analysis mode is abandoned, surrounding target interference is converted into the multi-frequency and space characteristics of the center target, and the target recognition accuracy in the multi-target scene is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal display driving technology, and specifically to a spatial-frequency fusion visual stimulation method and system. Background Technology

[0002] Traditional visual stimulation methods primarily rely on LCDs to generate steady-state visual evoked potential (VEVP) EEG signals. Current encoding / decoding methods mainly employ frequency encoding / decoding, frequency-phase encoding / decoding, or spatial encoding / decoding to design stimulus paradigms and target recognition. LCD methods suffer from poor fidelity in high-frequency stimulus signals due to limitations imposed by device refresh rates, resulting in low signal-to-noise ratios in the evoked EEG signals. Furthermore, existing encoding / decoding methods have the following problems: For frequency encoding / decoding, the stimulus target and frequency are typically in a one-to-one correspondence, limiting the number of identifiable targets to the number of stimulation frequencies. While frequency-phase encoding / decoding incorporates phase information on top of frequency, potentially increasing the number of targets that can be recognized, it places high demands on hardware parameters and significantly increases decoding complexity. Traditional spatial encoding, compared to the above two methods, can further increase the number of targets recognized with fewer stimuli, but due to the large number of acquisition channels, lower information decoding speed, and lower brain-computer interface communication rate, the accuracy and information transmission rate are insufficient. In addition, although some existing spatial coding schemes use 3×3 domains for spatial coding and decoding research, they have failed to design and optimize the spatial arrangement of the targets to be identified in a reasonable way. This results in a large number of targets in the domain, leading to a more complex computational workload and affecting the efficiency and speed of the interaction. Summary of the Invention

[0003] The purpose of this invention is to address the problems of low recognition accuracy, low information transmission rate, and limited number of recognition targets in the encoding and decoding scheme of traditional LCD high-frequency stimulation methods. Existing spatial encoding and decoding has failed to reasonably design and optimize the spatial arrangement of the targets to be recognized, resulting in a large amount of computation due to the large number of stimulation targets in the field, which affects the efficiency and speed of interaction. To address these shortcomings, a spatial-frequency fusion visual stimulation method and system is proposed.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A spatial-frequency fusion visual stimulation method includes the following steps:

[0006] S1. Select the central stimulus target and its four adjacent stimulus targets, for a total of five stimulus blocks;

[0007] S2. Set the arrangement of the stimulus blocks, including orthogonal arrangement and diagonal arrangement;

[0008] S3. Stimulate the two arrangements in sequence to obtain the stimulation frequency of the five stimulation blocks and the corresponding EEG signal amplitude.

[0009] S4. The optimal arrangement is the one that includes the most stimulation frequencies of the four surrounding adjacent stimulation frequencies of the central stimulation target and generates the largest amplitude of the EEG signal induced by the stimulation frequencies.

[0010] S5. Based on the optimal arrangement, gradually increase the distance from the four surrounding adjacent stimulus targets to the central stimulus target, and obtain the stimulation frequency of the five stimulus blocks and the corresponding EEG signal amplitude.

[0011] S6. Select the optimal distribution distance by judging the stimulation frequency and EEG signal amplitude;

[0012] S7. Keep the stimulation frequency of the central stimulus target unchanged, change the stimulation frequency of the four surrounding adjacent stimulus targets, acquire EEG signals, and obtain the distribution of stimulation frequency based on canonical correlation coefficient analysis.

[0013] S8. Based on the optimal spatial arrangement and its corresponding stimulus frequency distribution, a stimulus iteration optimization method is adopted to traverse all regions to be detected.

[0014] As a further preferred embodiment of the present invention, the stimulus iterative optimization method employs an iterative optimization strategy of random generation + constraint verification + local repair; specifically including:

[0015] S81. Set constraints.

[0016] Stimulation frequency range: The frequency value is limited to the high-frequency range of 30Hz to 40Hz;

[0017] Adjacent partition frequency interval: The frequency interval between any two adjacent partitions is ≥ 0.2Hz. This interval is determined by the data length of the target to be identified, and at least 5 seconds of data is required.

[0018] Number of partitions: determined by the number of hardware partitions in the visual stimulation device;

[0019] Local difference: The frequency difference between the central stimulus target and the frequencies of the four surrounding adjacent stimulus targets is > 1Hz. The greater the frequency difference, the easier it is to distinguish them. The number of frequency stimuli should be taken into account.

[0020] Uniform distribution: The frequency distribution is uniformly covered. The frequency of each frequency point is counted to ensure that the frequency of each frequency point is relatively equal, and to ensure uniform coverage of 30Hz~40Hz.

[0021] S82. Assign a frequency to each partition based on random sampling allocation;

[0022] S83. Determine whether the partition frequency interval constraint is met. If not, regenerate, up to 100 times.

[0023] S84. Traverse all partitions in the optimal spatial arrangement and determine whether the difference between the two smallest stimulus frequencies among the four adjacent stimulus targets is greater than or equal to 1Hz. If the difference is less than or equal to 1Hz, reallocate the frequencies of the partitions corresponding to these two stimulus targets and jump to S83.

[0024] S85. Determine whether the stimulus frequencies of the four adjacent stimulus targets are unique; if repetition is found, adjust the repetition frequency locally and jump to S83 to satisfy the condition that the stimulus frequencies of the four adjacent stimulus targets are unique.

[0025] A spatial-frequency fusion visual stimulation system, comprising,

[0026] The signal processing and feedback module is used to configure the brightness and flicker parameters of each partition block and the EEG signals acquired by the decoding signal acquisition module, which are then used to form the fifth signal and the third signal, respectively.

[0027] The backlight driving and control module is used to analyze the fifth signal, form a backlight driving signal, and control the flicker parameters and brightness of each zone of the backlight module in the display and stimulation module.

[0028] The display and stimulation module includes a display module and a backlight module. The display and stimulation module receives a backlight driving signal, drives the display module and the backlight module to perform visual stimulation, and generates a visual stimulation signal, namely the first signal.

[0029] The signal acquisition module is used to acquire the electroencephalogram (EEG) signals output by the cerebral cortex in response to visual stimuli.

[0030] The main control module is used to issue control signals based on the received third signal to achieve feedback control of the display and stimulation modules;

[0031] The signal processing and feedback module configures the brightness and flicker parameters of each partition of the display and stimulation module, and sends the configuration information, i.e., the fifth signal, to the backlight driving and control module. After receiving the fifth signal, the backlight driving and control module parses the parameter configuration information to form a backlight driving signal, which is then sent to the display and stimulation module. The display and stimulation module drives the display module and the backlight module to perform visual stimulation according to the backlight driving signal, generating a visual stimulation signal that stimulates the cerebral cortex and emits an EEG signal. The signal acquisition module collects the EEG signal, forms a second signal, and sends it to the signal processing and feedback module. The signal processing and feedback module decodes the signal to generate a third signal, i.e., the processed EEG signal, which is then sent to the main control module. After receiving the third signal, the main control module obtains a fourth signal through a recognition algorithm, generates the fourth signal, and compares it to the signal processing and feedback module. The fourth signal is then sent to the signal processing and feedback module to modify the brightness and flicker parameters of each partition.

[0032] As a further preferred embodiment of the present invention, the backlight module is configured as a multi-block backlight module composed of LED beads, wherein the brightness and flicker frequency of the LED beads in each block can be independently driven and controlled.

[0033] As a further preferred embodiment of the present invention, the second signal is a signal formed after the EEG signal has been denoised and filtered, and the second signal is transmitted to the signal processing and feedback module via wired or wireless means.

[0034] As a further preferred embodiment of the present invention, the main control module and the signal processing and feedback module are connected via a universal video interface.

[0035] As a further preferred embodiment of the present invention, the first signal is set as a sinusoidal signal with a fixed frequency and phase; the second signal is a visually evoked signal corresponding to the frequency of the first signal, having the highest amplitude at the fundamental frequency of the signal spectrum and the second highest amplitude at the harmonic frequency compared to other frequencies.

[0036] As a further preferred embodiment of the present invention, the fifth signal is configured as an SPI signal and a synchronization signal; the fourth signal is a data signal containing frequency and phase information.

[0037] The spatial-frequency fusion visual stimulation method and system proposed in this invention have the following advantages compared with the prior art:

[0038] 1. The spatial crosstalk characteristic of partitioned backlight is transformed into a multi-frequency feature advantage. The traditional single signal loudness analysis mode is abandoned. The interference of surrounding targets is transformed into the multi-frequency and spatial features of the central target, which greatly improves the target recognition accuracy in multi-target scenarios.

[0039] 2. Frequency point reuse is achieved by utilizing the features of surrounding targets, which significantly increases the number of targets compared to traditional methods. This avoids visual fatigue and stability issues caused by low-frequency use, breaks through the bottleneck of insufficient available frequency points, and effectively expands the number of targets that can be identified.

[0040] 3. This invention optimizes the arrangement of spatial frequency targets and achieves a stimulus paradigm of spatial-frequency fusion with fewer stimulus frequencies, thereby greatly improving the system performance and enhancing the speed and accuracy of interaction. Attached Figure Description

[0041] Figure 1 These are structural diagrams illustrating two spatial arrangement methods;

[0042] Figure 2 These are schematic diagrams of the structures after increasing the distance between two spatial arrangements;

[0043] Figure 3 These are schematic diagrams of different stimulus frequencies arranged in the same spatial configuration, along with their corresponding stimulus frequency distribution diagrams.

[0044] Figure 4 This is a schematic diagram of the module connections of the system involved in this invention.

[0045] The meanings of the reference numerals in the figure are as follows: 110, Display and Stimulation Module; 1101, Backlight Module; 1102, Display Module; 120, Signal Acquisition Module; 130, Signal Processing and Feedback Module; 140, Backlight Drive and Control Module; 150, Main Control Module. Detailed Implementation

[0046] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0047] This invention relates to a spatial-frequency fusion visual stimulation method and system, which adopts a spatial-frequency fusion visual stimulation system design based on a partitioned backlight visual stimulation mode. It utilizes the optimal spatial arrangement to achieve the design of the visual stimulation paradigm, which can effectively increase the number of targets recognized, improve the accuracy of high-frequency target recognition and information transmission rate, and significantly improve the performance of brain-controlled human-computer interaction, optimize system performance, and improve interaction speed and efficiency.

[0048] Example 1: A visual stimulation method based on spatial-frequency fusion, comprising the following steps:

[0049] S1. Select the central stimulus target and its four adjacent stimulus targets, for a total of five stimulus blocks.

[0050] Select a stimulus target and set up a group of 5 stimulus blocks, with the center frequency of a backlight block being the target to be identified and the surrounding 4 stimulus frequencies being the adjacent targets.

[0051] This invention employs a backlight module with 192 backlight partitions. In the display and stimulation module, five backlight block stimulation frequencies are selected as stimulation targets for this scheme. The central target is the stimulation target to be identified, and the four surrounding stimulation frequencies are adjacent targets. The frequency of the central stimulation target is 27Hz, and the frequencies of the adjacent stimulation targets are 32Hz, 33Hz, 25Hz, and 26Hz.

[0052] S2. Set the arrangement of the stimulus blocks, including orthogonal arrangement and diagonal arrangement.

[0053] S3. Stimulate the two arrangement methods in sequence to obtain the stimulation frequency of the 5 stimulation blocks. The stimulation frequency is the flashing frequency of the backlight in the stimulation target, which is composed of LED beads; and the corresponding EEG signal amplitude.

[0054] S4. The optimal arrangement is the one that includes the most stimulation frequencies of the four surrounding adjacent stimulation frequencies of the central stimulation target, and whose stimulation frequencies elicit the largest amplitude of the EEG signal.

[0055] like Figure 1 As shown, with the target stimulus block as the center, the surrounding adjacent stimulus blocks are arranged in a spatial arrangement relative to the target in the up, down, left, and right directions, which is an orthogonal arrangement; or they are arranged diagonally, which is a diagonal arrangement; the spacing between the stimulus blocks is the actual size of the backlight block.

[0056] For example, the display and stimulation module is a 27-inch display terminal (model 110). Each stimulation block measures 19mm x 30mm. The first stimulation arrangement is orthogonal: center 27Hz, top 32Hz, bottom 26Hz, left 33Hz, right 25Hz. The second stimulation arrangement is diagonal: center 27Hz, top left 33Hz, bottom left 26Hz, top right 32Hz, bottom right 25Hz.

[0057] Stimulation frequencies were applied, and the frequency components of the central stimulus target were measured using a frequency meter for the frequency distribution of the two arrangement patterns. The arrangement pattern in which the central target stimulus block contains the most frequencies from the corresponding surrounding adjacent stimulus blocks and generates the largest amplitude of the EEG signal induced by the stimulation frequency was selected as the optimal arrangement of the stimulus target if it exists.

[0058] S5. Based on the optimal arrangement, gradually increase the distance from the four surrounding adjacent stimulus targets to the central stimulus target, and obtain the stimulation frequency of the five stimulus blocks and the corresponding EEG signal amplitude.

[0059] S6. Select the optimal distribution distance by judging the stimulation frequency and EEG signal amplitude; that is, select the distribution distance where the stimulation frequency of the central stimulation target contains the most stimulation frequencies of the four surrounding adjacent stimulation targets and the stimulation frequency induces the largest EEG signal amplitude.

[0060] Combination Figure 2 After selecting the arrangement method, the distance between the surrounding adjacent stimulus targets and the central target is increased. Initially, the distance between the surrounding adjacent targets and the central target is increased to the distance of one backlight block. Subsequently, the distance is increased by one backlight block. Based on the stimulation frequency and EEG signal amplitude, the optimal distribution distance is selected. Combined with the optimal arrangement method selected in S4, the optimal spatial arrangement method is formed.

[0061] S7. Keep the stimulation frequency of the central stimulus target unchanged, change the stimulation frequency of the four surrounding adjacent stimulus targets, acquire EEG signals, and obtain the distribution of stimulation frequency based on canonical correlation coefficient analysis.

[0062] Two groups of targets with the same central target frequency are selected and arranged in the optimal spatial arrangement. Canonical correlation coefficient analysis is used to analyze the correlation between the two groups of stimulus targets. Combined with the correlation distribution of the surrounding stimulus frequencies, the stimulus target identification results are obtained, and the distribution of stimulus frequencies is determined.

[0063] For example, such as Figure 3 As shown, two sets of central stimulus targets with the same 27Hz frequency were set in a diagonal arrangement. One set (left) had peripheral stimulus targets at 33Hz (upper left), 26Hz (lower left), 32Hz (upper right), and 28Hz (lower right). The other set (right) had peripheral stimulus targets at 31Hz (upper left), 29Hz (lower left), 30Hz (upper right), and 28Hz (lower right). Canonical correlation analysis was performed on the EEG signals evoked by the two sets of central stimulus targets. Based on the differences in the correlation between the peripheral stimulus frequencies included in the central frequency, the identification results of different targets with the same stimulus frequency were obtained, thus determining the distribution of stimulus frequencies.

[0064] S8. Based on the optimal spatial arrangement and its corresponding stimulus frequency distribution, a stimulus iteration optimization method is adopted to traverse all regions to be detected.

[0065] As a further preferred embodiment of the present invention, the stimulus iterative optimization method employs an iterative optimization strategy of "random generation + constraint verification + local repair"; specifically including:

[0066] S81. Set constraints.

[0067] Stimulation frequency range: The frequency value is limited to the high-frequency range of 30Hz to 40Hz;

[0068] Frequency interval between adjacent partitions: The frequency interval between any two adjacent partitions is ≥ 0.2Hz. This interval is determined by the data length of the target to be identified. At least 5 seconds of data is required. This time length is obtained from the frequency resolution calculation principle of Fourier transform. The smaller the interval, the more stimulus targets can be identified.

[0069] Number of partitions: 192 partitions, each of which needs to be assigned a frequency. The number of partitions is determined by the number of hardware partitions in the visual stimulation device.

[0070] Local difference: The frequency difference between the central stimulus target and the frequencies of the four surrounding adjacent stimulus targets is > 1Hz. The greater the frequency difference, the easier it is to distinguish them. The number of frequency stimuli should be taken into account.

[0071] Uniform distribution: The frequency distribution should be as uniform as possible. The frequency of each frequency point should be counted to ensure that the frequency of each frequency point is relatively equal, which is a uniform distribution. Ensure uniform coverage of 30Hz~40Hz (avoid excessive concentration in some frequency bands); if some frequency bands are too dense, adjust some partition frequencies to shift them to sparser frequency bands.

[0072] S82. Assign a frequency to each partition based on random sampling; step size 0.1 Hz - 0.3 Hz.

[0073] S83. Determine whether the partition frequency interval constraint is met. If not, regenerate, up to 100 times.

[0074] S84. Traverse all partitions in the optimal spatial arrangement and determine whether the difference between the two smallest stimulus frequencies among the four adjacent stimulus targets is greater than or equal to 1Hz. If the difference is less than or equal to 1Hz, reallocate the frequencies of the partitions corresponding to these two stimulus targets and jump to S83.

[0075] S85. Determine whether the stimulus frequencies of the four adjacent stimulus targets are unique; if repetition is found, adjust the repetition frequency locally and jump to S83 to satisfy the condition that the stimulus frequencies of the four adjacent stimulus targets are unique.

[0076] By using the above optimization method, all detection areas were traversed, and the design and expansion of the stimulation frequency of 192 zones were realized.

[0077] Example 2: Combination Figure 4 A spatial-frequency fusion visual stimulation system includes a signal processing and feedback module 130, used to configure the brightness and flicker parameters of each partition block and the EEG signals acquired by the decoding signal acquisition module 120, forming a fifth signal and a third signal respectively; these signals are sent to the main control module 150, thereby realizing feedback control of the display and stimulation module 110. The third signal is a feedback control signal.

[0078] The backlight driving and control module 140 is used to analyze the fifth signal, form a backlight driving signal, and realize the control of the flicker parameters and brightness of each zone of the backlight module 1101 in the display and stimulation module 110;

[0079] The display and stimulation module 110 includes a display module 1102 and a backlight module 1101. The display and stimulation module 110 receives a backlight driving signal and drives the display module 1102 and the backlight module 1101 to provide visual stimulation, generating a visual stimulation signal, i.e., a first signal. The display module 1102 is a liquid crystal panel used to display images. The backlight module 1101 is configured as a multi-segment backlight module constructed from LEDs, where the brightness and flicker frequency of the LEDs in each segment can be independently driven and controlled. For example, the backlight module 1101 consists of backlight blocks with 16 rows and 12 columns, totaling 192 segments. The visual stimulation source includes the brightness, frequency, and phase information of each segment of the backlight block.

[0080] The signal acquisition module 120 receives EEG signals induced by visual stimuli from the display and stimulation module 110. After processing, these signals are converted into a second signal and transmitted via wired / wireless means to the signal processing and feedback module 130 for further processing. EEG signals are potential signals induced by changes in cortical potentials in the brain caused by visual stimuli acting on the human eye's visual channel. The transmission of EEG signals primarily utilizes Bluetooth or serial communication.

[0081] The main control module 150 is used to issue a control signal, i.e., a fourth signal, based on the received third signal; to realize feedback control of the display and stimulation module 110; the main control module 150 is connected to the signal processing and feedback module 130 through a general video interface; the fourth signal is transmitted to the signal processing and feedback module 130 wirelessly, and finally realizes the parameter setting of the display and stimulation module partition blocks.

[0082] The signal processing and feedback module 130 configures the brightness and flicker parameters of each partition of the display and stimulation module 110, and sends the configuration information, i.e., the fifth signal, to the backlight driving and control module 140. After receiving the fifth signal, the backlight driving and control module 140 parses the parameter configuration information to form a backlight driving signal, which is sent to the display and stimulation module 110. The display and stimulation module 110 drives the display module 1102 and the backlight module 1101 to perform visual stimulation according to the backlight driving signal, generating a visual stimulation signal that stimulates the cerebral cortex and emits an EEG signal. The signal acquisition module 120 acquires the EEG signal, forms a second signal, and sends it to the signal processing and feedback module 130. The signal processing and feedback module 130 decodes the signal to generate a third signal, i.e., the processed EEG signal, which is sent to the main control module 150. After receiving the third signal, the main control module 150 obtains a fourth signal through a recognition algorithm, generates a fourth signal, and the conclusion obtained after comparison is the fourth signal, which is sent to the signal processing and feedback module 130 to provide feedback and modify the brightness and flicker parameters of each partition.

[0083] The main control module 150 sends the stimulation frequency and phase configuration information of each partition block to the signal processing and feedback module 130. The signal processing and feedback module 130 configures the stimulation of the corresponding partition blocks through the backlight drive and control module, and finally presents the stimulation frequency and phase of each partition block through the display stimulation module. When the human eye visually focuses on a certain stimulation block of the display and stimulation module 110, the signal acquisition module 120 obtains a first signal by acquiring the signal of the corresponding position of the cerebral cortex. After noise reduction and filtering, the signal is used to obtain a second signal, which is then sent to the signal processing and feedback module 130 via Bluetooth or serial port. The signal processing and feedback module 130 performs a Fourier transform on the acquired time-domain second signal to the frequency domain to obtain the frequency-domain EEG signal, and compares the frequency and phase information of the EEG signal with the pre-set stimulation frequencies and phases of all partition blocks. When the correlation is the largest, it is marked that the EEG signal corresponds to a specific partition block, and a feedback control signal is sent to realize the control and interaction of the display and stimulation module 110.

[0084] The first signal is a sinusoidal signal with a fixed frequency and phase; the second signal is a visual evoked signal corresponding to the frequency of the first signal, having the highest amplitude at the fundamental frequency of the signal spectrum and the second highest amplitude at the harmonic frequencies compared to other frequencies; the second signal is a signal formed by noise reduction and filtering of the EEG signal, and the second signal is transmitted to the signal processing and feedback module 130 via wired or wireless means. The fifth signal is set as an SPI signal and a synchronization signal; the fourth signal is a data signal containing frequency and phase information.

[0085] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A spatial-frequency fusion visual stimulation method, characterized in that, Includes the following steps: S1. Select the central stimulus target and its four adjacent stimulus targets, for a total of five stimulus blocks; S2. Set the arrangement of the stimulus blocks, including orthogonal arrangement and diagonal arrangement; S3. Stimulate the two arrangements in sequence to obtain the stimulation frequency of the five stimulation blocks and the corresponding EEG signal amplitude. S4. The optimal arrangement is the one that includes the most stimulation frequencies of the four surrounding adjacent stimulation frequencies of the central stimulation target and generates the largest amplitude of the EEG signal induced by the stimulation frequencies. S5. Based on the optimal arrangement, gradually increase the distance from the four surrounding adjacent stimulus targets to the central stimulus target, and obtain the stimulation frequency and corresponding EEG signal amplitude of the five stimulus blocks. S6. Select the optimal distribution distance by judging the stimulation frequency and EEG signal amplitude; S7. Keep the stimulation frequency of the central stimulus target unchanged, change the stimulation frequency of the four surrounding adjacent stimulus targets, acquire EEG signals, and obtain the distribution of stimulation frequency based on canonical correlation coefficient analysis. S8. Based on the optimal spatial arrangement and its corresponding stimulus frequency distribution, a stimulus iteration optimization method is adopted to traverse all regions to be detected.

2. The visual stimulation method based on spatial-frequency fusion according to claim 1, characterized in that, The stimulus iterative optimization method adopts an iterative optimization strategy of random generation + constraint verification + local repair; Specifically, it includes: S81. Set constraints. Stimulation frequency range: The frequency value is limited to the high-frequency range of 30Hz to 40Hz; Adjacent partition frequency interval: The frequency interval between any two adjacent partitions is ≥ 0.2Hz. This interval is determined by the data length of the target to be identified, and at least 5 seconds of data is required. Number of partitions: determined by the number of hardware partitions in the visual stimulation device; Local difference: The frequency difference between the central stimulus target and the frequencies of the four surrounding adjacent stimulus targets is > 1 Hz; Uniform distribution: The frequency distribution is uniformly covered, ensuring that the frequency points of each frequency point are relatively equal, which is called uniform distribution, ensuring uniform coverage of 30Hz~40Hz; S82. Assign a frequency to each partition based on random sampling allocation; S83. Determine whether the partition frequency interval constraint is met. If not, regenerate, up to 100 times. S84. Traverse all partitions in the optimal spatial arrangement and determine whether the difference between the two smallest stimulus frequencies among the four adjacent stimulus targets is greater than or equal to 1Hz. If the difference is less than or equal to 1Hz, reallocate the frequencies of the partitions corresponding to these two stimulus targets and jump to S83. S85. Determine whether the stimulus frequencies of the four adjacent stimulus targets are unique; if repetition is found, adjust the repetition frequency locally and jump to S83 to satisfy the condition that the stimulus frequencies of the four adjacent stimulus targets are unique.

3. A system employing the spatial-frequency fusion visual stimulation method according to claim 1 or 2, characterized in that, include, The signal processing and feedback module is used to configure the brightness and flicker parameters of each partition block and the EEG signals acquired by the decoding signal acquisition module, which are then used to form the fifth signal and the third signal, respectively. The backlight driving and control module is used to analyze the fifth signal, form a backlight driving signal, and control the flicker parameters and brightness of each zone of the backlight module in the display and stimulation module. The display and stimulation module includes a display module and a backlight module. The display and stimulation module receives a backlight driving signal, drives the display module and the backlight module to perform visual stimulation, and generates a visual stimulation signal, namely the first signal. The signal acquisition module is used to acquire the electroencephalogram (EEG) signals output by the cerebral cortex in response to visual stimuli. The main control module is used to issue control signals based on the received third signal to achieve feedback control of the display and stimulation modules; The signal processing and feedback module configures the brightness and flicker parameters of each partition of the display and stimulation module, and sends the configuration information, i.e., the fifth signal, to the backlight driving and control module. After receiving the fifth signal, the backlight driving and control module parses the parameter configuration information to form a backlight driving signal, which is then sent to the display and stimulation module. The display and stimulation module drives the display module and the backlight module to perform visual stimulation according to the backlight driving signal, generating a visual stimulation signal that stimulates the cerebral cortex and emits an EEG signal. The signal acquisition module collects the EEG signal, forms a second signal, and sends it to the signal processing and feedback module. The signal processing and feedback module decodes the signal to generate a third signal, i.e., the processed EEG signal, which is then sent to the main control module. After receiving the third signal, the main control module obtains a fourth signal through a recognition algorithm, generates the fourth signal, and compares it to the signal processing and feedback module. The fourth signal is then sent to the signal processing and feedback module to modify the brightness and flicker parameters of each partition.

4. The system according to claim 3, characterized in that, The backlight module is configured as a multi-block backlight module composed of LED beads, and the brightness and flicker frequency of the LED beads in each block can be driven and controlled independently.

5. The system according to claim 3, characterized in that, The second signal is a signal formed after the EEG signal has been denoised and filtered, and the second signal is transmitted to the signal processing and feedback module via wired or wireless means.

6. The system according to claim 3, characterized in that, The main control module and the signal processing and feedback module are connected via a general video interface.

7. The system according to claim 3, characterized in that, The first signal is set as a sinusoidal signal with a fixed frequency and phase; the second signal is a visually evoked signal corresponding to the frequency of the first signal, having the highest amplitude at the fundamental frequency of the signal spectrum and the second highest amplitude at the harmonic frequency compared to other frequencies.

8. The system according to claim 3, characterized in that, The fifth signal is set as an SPI signal and a synchronization signal; the fourth signal is a data signal containing frequency and phase information.

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