The Design Of The Online BCI System Based On EEG

Background Brain-Computer Interface(BCI)is a kind of technology that enables people to communicate with computer or control devices with brain signals.The brain-computer interface technology research has made certain achievements,but most of these studies stop in the laboratory research stage,the main reason is that the anti-interference ability of brain electrical signal acquisition and processing equipment is poor,and these equipments demand high environment condition.Secondly,users need a training process because many studies use evoke EEG as control signal.Thirdly,the processing methods of some studies is in the case of off-line.Finally,That the EEG acquisition devices are huge in volume with expensive cost also limits them widely used.Objective Aiming at the problems that prevent BCI out of the lab,the aim of this study was to design an on-line BCI equipment which can be used in the general environment.This study uses the spontaneous EEG as the control signal.Users do not need training and any user can use directly.Methods ⑴The paper uses EEG acquisition equipment,Emotiv EPOC+,to acquire the EEG signal of frontal and occipital area,and uses Bluetooth module with a USB interface to transmit these signals to computer.⑵According to C++ software development kit based on Windows platform provided by EMOTIV company,the paper reads the data of the USB interface of Bluetooth module,stores it in a computer,extracts the EEG signal of AF3 and AF4 channels by analysising it,and transmits them through another USB interface of Bluetooth adapter.This whole process is implemented using C++programming.⑶This research uses FPGA to control the RS-232 serial port of Bluetooth module,which is used to receive the Bluetooth signal containing the EEG signal of AF3 and AF4 channels.They are separated and sent to TFT LCD screen to be displayed.TFT LCD screen shows their amplitude and time.(4)The paper shape the waveform of the processed EEG signal to obtain a square wave signal with different duty cycle.The difference between deliberately eyes closed and eyes open signal and baseline is greater than 100 uv.Setting a threshold value according to the difference,The square wave signal isconverted into a pulse signal when the amplitude of square wave signal reaches the threshold value.The pulse signal is used as the trigger signal to cyclically select the 5different output results,and the output result is the final result if this output can be maintained 10 s.Results TFT LCD screen can display the collected real-time EEG signals,it not only shows the rise wave when close their eyes and downward wave when open their eyes,but also displays signal strength.In the general experimental environment,the difference of the deliberate blink signal amplitude of the different subjects is not big after an experiment with 12 subjects.They can use their deliberate blink signal to choose 5different output results finally.Conclusion Therefore,the present study provides a portable,inexpensive brain computer interface device for the physical paralysis of the patient to communicate with the outside world.,which is suitable to be used in general environment.