Brain-computer interface method based on steady-state asymmetric visual evoked potential

A visual evoked potential and asymmetric technology, applied in the field of brain-computer interface, can solve problems such as difficult to effectively extract and identify targets, affect SSVEP performance, and weak EEG signal amplitude, so as to avoid visual fatigue, improve recognition performance, Effect of suppressing background common mode noise

Active Publication Date: 2020-08-25
TIANJIN UNIV
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  • Application Information

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Problems solved by technology

However, staring directly at the stimulus can easily cause strong visual fatigue of the subjects, which affects the performance of SSVEP.
At the same time, in the SSVEP research where high-frequency signals are used as stimuli, the amplitude of the EEG signal induced by direct gaze at the stimulus target is weak and the noise is strong, making it difficult to effectively extract and identify the target.

Method used

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  • Brain-computer interface method based on steady-state asymmetric visual evoked potential
  • Brain-computer interface method based on steady-state asymmetric visual evoked potential
  • Brain-computer interface method based on steady-state asymmetric visual evoked potential

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Embodiment 1

[0037] According to the spatial asymmetry characteristics of the brain's visual stimulus response, the present invention designs a new asymmetric encoding paradigm based on SSVEP by combining the stability and high decoding performance of the SSVEP system, and develops a coding paradigm suitable for decoding Efficient algorithm for SSaVEP.

[0038] The technical process is: design a new SSaVEP coding paradigm, build a complete EEG signal acquisition device, collect the subject's EEG signal data under the guidance of the experimental system, and then store the EEG data passed through the EEG amplifier, and then carry out Certain preprocessing, feature extraction, and finally identification.

Embodiment 2

[0040] Combine below Figure 1-Figure 5 The scheme in embodiment 1 is further introduced, see the following description for details:

[0041] 1. Visual Stimulus Paradigm Design

[0042] The present invention designs an SSaVEP encoding paradigm with N instruction sets. Taking the character encoding paradigm of four instructions as an example, characters A, B, C, and D are distributed in 2×2, and asterisks indicate the target characters to be gazed at, such as figure 2 shown. The subject's eyes were kept level with the center of the screen (usually at a distance of 70 cm), and the subject stared at the center of the target. At different times, stimulus signals appeared around the visual field, evoking SSaVEP with spatial information.

[0043] like image 3 As shown, a schematic diagram of the spatial distribution of a single instruction is displayed using the xoy coordinate axis. In order to better show the location distribution of asymmetric instructions, in the present in...

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Abstract

The invention discloses a brain-computer interface method based on steady-state asymmetric visual evoked potentials, and the method comprises the steps: constructing an SSaVEP coding normal form withN instruction sets, enabling a visual field fixation point to be at an original point, and enabling a visual stimulation signal to appear around the original point in two different time periods; acquiring electroencephalogram signal data of a subject by using a Neuroscan Synamps2 system, and performing preprocessing to extract a feature signal; constructing a spatial filter, and respectively obtaining a training set template and a test set template by utilizing the spatial filter to realize feature enhancement of the SSaVEP; extracting correlation coefficients of the training set template andthe test set template by using a CCA algorithm to maximize the potential correlation. In mode matching, the relationship between the training set template and the test signal is represented by a vector, a final correlation coefficient decision value is further obtained, and a target category is obtained based on the decision value. According to the technology, the signal-to-noise ratio of SSVEP can be remarkably improved, and the technology is suitable for a low frequency band, a medium frequency band and a high frequency band; and meanwhile, visual fatigue can be reduced by utilizing a hiddenvisual fixation mode.

Description

technical field [0001] The invention relates to the field of brain-computer interface, in particular to a brain-computer interface method based on Steady-State asymmetrically Visual Evoked Potential (SSaVEP). Background technique [0002] Brain-Computer Interface (BCI) refers to a system that can replace, repair, enhance, supplement or improve the normal output of the central nervous system, thereby improving the interaction between the internal and external environment. According to the placement of electrode sensors that collect physiological signals, it can be divided into invasive BCI and non-invasive BCI. For non-invasive BCI, Steady-State Visual Evoked Potential (SSVEP) is widely used as a brain control signal because of its good robustness. At present, the BCI system based on SSVEP has an extremely high information transmission rate. [0003] SSVEP refers to the periodic scalp EEG (Electroencephalography, EEG) signal caused by the flickering of external visual stimu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F3/01
CPCG06F3/015
Inventor 许敏鹏越亮肖晓琳明东
Owner TIANJIN UNIV
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