Study On Steady-state Visual Evoked Potential Visual Stimulator Based On Android

Electroencephalogram(EEG) has a strong link with human consciousness, perception and other active states, reflecting the people’s overall electrical activity of brain cells. Electrode is used to collect EEG on the scalp surface and then analysis is conducted to identify different awareness activities. In this way, a communication control system can be formed without the output of brain peripheral nerves and muscles operation, which is also known as Brain-Computer Interface(BCI). Steady-state visual evoked potential(SSVEP) refers to that when the human eyes are visually stimulated by a periodic stimulation frequency, the human brain’s visual cortex will generate a continuous response that related to the stimulus frequency. Compared with other types of brain signals, steady-state visual evoked potential has many advantages, such as easy to extract, easy for analysis and stable, etc., so it is widely used as an input signal in the brain-computer interface control system. Visual stimulation is an external device of evoking steady-state visual evoked potential EEG, and also the human-computer interaction interface,more importantly, it is a prerequisite for the collection of steady-state visual evoked potential EEG.In this paper, a set of visual stimulator based on steady-state visual evoked potential is designed with Android system, which can not only successfully induce the EEG of steady-state visual evoked potential, but also successfully applied in the real-time online EEG phone dialing system, to achieve phone number dialing with EEG instead of body movements. Visual stimulator is divided into three parts: single-frequency stimulate module, multi-frequency stimulate module and graphic stimulate module. Among them, multi-frequency stimulate module has a total of 12 frequencies while graphics stimulate module adopts checkerboard stimulation pattern. In addition, EEG acquisition experiment is also designed on the basis of Android visual stimulator, through pre-treatment, feature extraction, pattern classification and a series of algorithms, it can convert the EEG to control command, that instruct the external communication module to realize EEG dialing.By conducting single-frequency stimulate feedback experiment on Android-based visual stimulator, it confirmed that the designed visual stimulator is feasible. In addition, by comparing the experimental result with the laboratory original experiment result of LED visual stimulator, it can be seen that the processing speed of Android visual stimulator is 4.5% higher than LED visual stimulator. Moreover, Android visual stimulator can be used in most Android phones,tablet and other mobile devices on the current market, which has greatly improved the convenience and mobility of visual stimulator.