CN102799267B - Multi-brain-computer interface method for three characteristics of SSVEP (Steady State Visual Evoked Potential), blocking and P300 - Google Patents

Abstract

The invention relates to the field of medical equipment in order to improve the transmission rate of system information greatly. The invention adopts the technical scheme that the multi-brain-computer interface method for three characteristics of SSVEP (Steady State Visual Evoked Potential), blocking and P300 comprises the following steps: adopting a computer and an electroencephalogram acquisition system including an electroencephalogram electrode, an electroencephalogram amplifier and an electroencephalogram filter, wherein the computer further comprises an EEG (Electroencephalo-Graph) analytical program and a stimulation and induction user interface; acquiring electroencephalogram data of multiple channels by using the electroencephalogram acquisition system; generating an electroencephalogram signal from cerebral cortex, detecting the electroencephalogram signal by using the electroencephalogram electrode, amplifying by using the electroencephalogram amplifier, and filtering and inputting to the computer; and carrying out subsequent data process on the acquired electroencephalogram data to extract corresponding SSVEP, SSVEP blocking and P300 characteristic signals, thus the characteristics are applied to mode recognition of experimental tasks. The multi-brain-computer interface method is mainly applied to the design and manufacturing of the medical equipment.

Description

SSVEP and block and the many brain-computer interface methods of P300 tri-feature

Technical field

The present invention relates to medical instruments field, particularly relate to the SSVEP and blocking-up and the many brain-computer interface methods of P300 tri-feature that adopt in medicine equipment.

Background technology

Normal person is when the flicker being subject to a certain frequency (being generally greater than 6Hz) stimulates, and there will be the response consistent with frequency of stimulation or its harmonic wave in corresponding brain electricity, this response is exactly so-called Steady State Visual Evoked Potential; P300 is then the posivtive spike that about 300ms occurs in brain electricity after target stimulates; SSVEP blocking-up (SSVEPB) is then the phenomenon that the energy of the SSVEP signal occurred in the new normal form of SSVEP and P300 fusion is suppressed when goal stimulus occurs.

The definition of the BCI that first time brain-computer interface (Brain-Computer Interface, BCI) international conference provides is: " BCI is a kind of communication control system not relying on brain nervus peripheralis and the normal output channel of muscle." in current achievement in research; it is mainly by gathering and analyze the EEG signals of different conditions servant; then use certain engineering means directly to exchange and control channel with setting up between computing machine or other electronic equipment at human brain; thus realize a kind of brand-new message exchange and control technology, can particularly those lose basic extremity motor function but the patient had a normal thinking provides a kind of approach carrying out information communication and control with the external world for disabled person.Namely can not need language or limb action, directly express wish by controlling brain electricity or handle external device.For this reason, BCI technology also more and more comes into one's own.

In recent years, the BCI (hybrid BCI, HBCI) mixing normal form studies widely as the new direction and receiving of BCI System Development.HBCI system is combined with other human-computer interface systems a sub-BCI system, thus export control command sooner, more accurately.BCI (pure hybrid BCI, the PHBCI) system of pure mixing normal form is then multiple sub-BCI system combined.The PHBCI system of current existence mostly in conjunction with SSVEP and ERD signal, or in conjunction with P300 and ERD signal.This kind of PHBCI system, by multiple different EEG signal parallel processing, is namely used for different EEG signal to process different tasks.Although this hybrid mode can improve execution efficiency in multitask situation, the judgment accuracy of single task role cannot be improved.

The combination being all vision induced P300 current potential and SSVEP EEG signals also exists natural convenience.P300 current potential is cognitive potential, and SSVEP is by the passive generation of environmental stimuli, and therefore both appearance do not exist the contradiction in mechanism.On the other hand, there is difference in the generation region of P300 current potential and the generation region of SSVEP signal, turn, this avoids two kinds of characteristic signal conflicts spatially.The people such as Panicker propose a kind of asynchronous PHBCI system based on SSVEP and P300 signal.The advantage of this system utilizes SSVEP characteristic signal as the status switch of experimenter, but remain unhelpful for the judgment accuracy and rate of information transmission improving task.

In addition, traditional brain-computer interface only has a system usually, and therefore execution efficiency is general lower.

Summary of the invention

The present invention is intended to overcome the deficiencies in the prior art, can significantly improve system information transmissions rate, for achieving the above object, the technical scheme that the present invention takes is, SSVEP and block and the many brain-computer interface methods of P300 tri-feature, comprise the steps: to realize by means of comprising electrode for encephalograms and eeg amplifier, the eeg collection system of brain electrical filter and computing machine, its Computer comprises again EEG routine analyzer and Induced by Stimulation user interface; Use eeg collection system to gather multichannel eeg data, experimenter is undisturbedly seated at and is about on the arm-chair of 1m apart from screen, watches the flicker of the stimulation normal form on computer screen attentively, the number of times of silent number target character flicker in the heart in scitillation process; Experimenter's brain electricity can produce corresponding change in the process: EEG signals produces at cerebral cortex, through eeg amplifier amplification, filtering after inputs computing machine after being detected by electrode for encephalograms; Collect eeg data extracts corresponding SSVEP, SSVEP blocking-up and P300 characteristic signal through follow-up data processing again, thus by the pattern-recognition of these feature application in experimental duties.

The flicker of the stimulation normal form on computer screen is specially: when namely a certain character is in event period as stimulation, except this character, other all characters are all bright to be secretly alternately presented on screen, the frequency alternately presented is at more than 6Hz, the Character Intensity being in event period is constant, but font face changes; When experimenter accepts non-target stimulation, can be brought out it and produce SSVEP feature brain electricity; When experimenter accepts target stimulation, SSVEP signal will be blocked, and meanwhile will produce P300 current potential.

Each SSVEP, SSVEP block and many brain-computer interfaces of P300 tri-feature are independently BCI systems; Stimulation normal form on computer screen is the stimulation interface simultaneously presenting multiple different command collection in face of user, and each stimulation interface is respectively the stimulation interface of many brain-computer interfaces of SSVEP, SSVEP blocking-up and P300 tri-feature; The stimulation interface of multiple different command collection is except flicker frequency is different with character, and other parameter is all just the same; When user thinks selection character and watches this character attentively, first determine according to the time of occurrence of SSVEPB and P300, which stimulation interface user is watching attentively, then determines which character user is watching attentively by judging the SSVEP frequency range characteristic sum SSVEPB frequency range feature of user.

Utilize rate of information transmission to represent the work efficiency of many brain-computer interfaces, its expression formula is as follows

$\mathrm{ITR}=\frac{60(P{\log }_{2}P+(1-P){\log }_2\left(\frac{1-P}{N-1}\right)+{\log }_{2}N)}{T}$

In formula: P is character recognition accuracy, N is number of characters to be selected, and T is select time.

Technical characterstic of the present invention and effect:

Compared with the single BCI system of tradition, can significantly improve system information transmissions rate.This system can bring out SSVEP, SSVEP blocks and P300 feature, and utilize SSVEP and SSVEP disabling signal to control the switching of multiple BCI system, SSVEP is utilized to block and the selection of P300 signal realization to character, these three kinds of signal characteristic inducement mechanisms involved by invention are different, avoid the contradiction in mechanism; The generation time of SSVEP with SSVEP disabling signal is different; SSVEP blocks different with frequency field with the generation locus of P300 signal; Generation time, the space of SSVEP and P300 signal are all different with frequency field.The brain-computer interface system that further research can improve, is expected to obtain considerable Social benefit and economic benefit.

Accompanying drawing explanation

The structured flowchart of Fig. 1 apparatus of the present invention.

Fig. 2 P300-SSVEP-Speller normal form.

Fig. 3 P300-SSVEP-Speller sequential chart.

Fig. 4 parallel mixing brain machine interface system interface.

Embodiment

The present invention devises a kind of based on SSVEP, SSVEP blocks and the multi-mode brain-computer interface (BCI) of P300 tri-feature stimulates normal form, by SSVEP feature, SSVEPB characteristic sum P300 feature is effective must be combined, set up the BCI system of multiple different mode functioning in parallel, thus extend BCI command set, significantly improve the rate of information transmission of BCI.

Its techniqueflow is: design the experiment of new normal form, put up the eeg signal acquisition device needed for experiment, then under experimental system instructs, acquisition operations person's EEG signals data, carry out certain pre-service, feature extraction again after being stored, finally use linear discriminant analysis to carry out its judgment accuracy of classified calculating and rate of information transmission.

The present invention proposes a kind of many PHBCI parallel system newly, this system can bring out SSVEP simultaneously, SSVEPB and P300 feature, and can in the time, three separates by space and frequency field, and the effective binding energy of these three kinds of different characteristic signals enough significantly improves the rate of information transmission of BCI system.

Purport of the present invention proposes a kind of many BCI parallel system newly to bring out normal form, compared with the single BCI system of tradition, can significantly improve system information transmissions rate.This system can bring out SSVEP, SSVEP blocks and P300 feature, and utilize SSVEP and SSVEP disabling signal to control the switching of multiple BCI system, SSVEP is utilized to block and the selection of P300 signal realization to character, these three kinds of signal characteristic inducement mechanisms involved by invention are different, avoid the contradiction in mechanism; The generation time of SSVEP with SSVEP disabling signal is different; SSVEP blocks different with frequency field with the generation locus of P300 signal; Generation time, the space of SSVEP and P300 signal are all different with frequency field.The brain-computer interface system that further research can improve, is expected to obtain considerable Social benefit and economic benefit.

Fig. 1 is the structural representation of apparatus of the present invention.This design comprises the parts such as the eeg collection system such as electrode for encephalograms and eeg amplifier and computing machine, and wherein computing machine part comprises again the design at the design of EEG routine analyzer and user interface mainly Induced by Stimulation interface.The brain electricity digital acquisition system using Neurosean company to produce gathers brain electricity, gathers multichannel eeg data.Experimenter is undisturbedly seated at and is about on the arm-chair of 1m apart from screen, watches the flicker of the stimulation normal form on computer screen attentively, the number of times (being conducive to concentrated experimenter's energy) of silent number target character flicker in the heart in scitillation process.Experimenter's brain electricity can produce corresponding change in the process: EEG signals produces at cerebral cortex, through eeg amplifier amplification, filtering after inputs computing machine after being detected by electrode for encephalograms.Collect eeg data extracts corresponding SSVEP, SSVEP blocking-up and P300 characteristic signal through follow-up data processing again, thus by the pattern-recognition of these feature application in experimental duties.

Main points of the present invention are that the design of scheme is brought out in visual stimulus.

The design of scheme is brought out in 1 visual stimulus

P300-SSVEP-Speller improves on the basis that Farwell character matrix is tested, as shown in Figure 2.Each word stimulates it to produce P300 current potential by changing font.Meanwhile, other characters are with the stable flicker of certain frequency.When character 5 is as stimulation, Fig. 2 a and Fig. 2 b alternately presents respectively on the computer screen, and its frequency is 15Hz (can be greater than the frequency of 6Hz for other).Therefore, when experimenter accepts non-target stimulation, can be brought out it and produce SSVEP feature brain electricity; When experimenter accepts target stimulation, SSVEP signal will be blocked, and meanwhile will produce P300 current potential.The position of each character is changeless, when character 5 stimulates as shown in Figure 2.It is exactly that the character paid close attention to of experimenter there occurs action change that Target stimulates, if experimenter pays close attention to character 2 now, so only has character 2 to change font and is only target and stimulates.

Fig. 3 is the single character blinking sequential chart of P300-SSVEP-Speller normal form.Occur outside event at character, this character is always with certain fixing frequency scintillation.

Each P300-SSVEP-Speller is an independently BCI system.The present invention, based on the basis of P300-SSVEP-Speller, devises the BCI system of multiple functioning in parallel.For two BCI systems, its system interface design diagram as shown in Figure 4.In face of user, provide two character manipulation meetings, be respectively digital interface and alpha interface, each interface is an independently P300-SSVEP-Speller system simultaneously.These two BCI systems except various flicker frequencies (suppose that digital interface is glimmered with 15Hz, textual interface glimmers with 16Hz) different with character Command outside, other parameter is all just the same.So when user thinks selection character Command and watches this character attentively, by judging the SSVEP frequency range characteristic sum SSVEPB frequency range feature of user, we can first determine which BCI system user is watching attentively, then determine which character user is watching attentively according to the time of occurrence of SSVEPB and P300.

2 rate of information transmission

Usually utilize rate of information transmission to represent the work efficiency of BCI system, its expression formula is as follows

$\mathrm{ITR}=\frac{60(P{\log }_{2}P+(1-P){\log }_2\left(\frac{1-P}{N-1}\right)+{\log }_{2}N)}{T}$

In formula: P is character recognition accuracy, N is number of characters to be selected, and T is select time.

Beneficial effect

The design's normal form significantly can improve the rate of information transmission of BCI system, and for many BCI parallel system of two autonomous systems of 5.1, the rate of information transmission of BCI system more single than tradition improves at least 30%.If utilize 3 independent P300-SSVEP-Speller to form many BCI parallel system, so its rate of information transmission at least improves 49%.

The present invention devises and a kind ofly to block and the parallel mixing normal form brain machine interface system of P300 tri-feature based on SSVEP, SSVEP.This invention may be used for the fields such as disability rehabilitation, electronic entertainment, Industry Control, studies the brain machine interface system that can improve further, is expected to obtain considerable Social benefit and economic benefit.

Claims (3)

1. a SSVEP and block and the many brain-computer interface methods of P300 tri-feature, it is characterized in that, comprise the steps: to realize by means of comprising electrode for encephalograms and eeg amplifier, the eeg collection system of brain electrical filter and computing machine, its Computer comprises again EEG routine analyzer and Induced by Stimulation user interface; Use eeg collection system to gather multichannel eeg data, experimenter is undisturbedly seated at apart from the arm-chair of screen 1m, watches the flicker of the stimulation normal form on computer screen attentively, the number of times of silent number target character flicker in the heart in scitillation process; Experimenter's brain electricity can produce corresponding change in the process: EEG signals produces at cerebral cortex, through eeg amplifier amplification, filtering after inputs computing machine after being detected by electrode for encephalograms; Collect eeg data extracts corresponding SSVEP, SSVEP blocking-up and P300 characteristic signal through follow-up data processing again, thus by the pattern-recognition of these feature application in experimental duties;

The flicker of the stimulation normal form on computer screen is specially: when namely a certain character is in event period as stimulation, except this character, other all characters are all bright to be secretly alternately presented on screen, the frequency alternately presented is at more than 6Hz, the Character Intensity being in event period is constant, but font face changes; When experimenter accepts non-target stimulation, can be brought out it and produce SSVEP feature brain electricity; When experimenter accepts target stimulation, SSVEP signal will be blocked, and meanwhile will produce P300 current potential.

2. SSVEP as claimed in claim 1 and blocking and the many brain-computer interface methods of P300 tri-feature, it is characterized in that, many brain-computer interfaces of each SSVEP, SSVEP blocking-up and P300 tri-feature are independently BCI systems; Stimulation normal form on computer screen is the stimulation interface simultaneously presenting multiple different command collection in face of user, and each stimulation interface is respectively the stimulation interface of many brain-computer interfaces of SSVEP, SSVEP blocking-up and P300 tri-feature; The stimulation interface of multiple different command collection only has flicker frequency different with character; When user thinks selection character and watches this character attentively, first determine according to the time of occurrence of SSVEPB and P300, which stimulation interface user is watching attentively, then determines which character user is watching attentively by judging the SSVEP frequency range characteristic sum SSVEPB frequency range feature of user.

3. SSVEP as claimed in claim 1 and blocking and the many brain-computer interface methods of P300 tri-feature, it is characterized in that, utilize rate of information transmission to represent the work efficiency of many brain-computer interfaces, its expression formula is as follows:

$\mathrm{ITR}=\frac{60(P{\log }_{2}P+(1-P){\log }_2\left(\frac{1-P}{N-1}\right)+{\log }_{2}N)}{T}$

In formula: P is character recognition accuracy, N is number of characters to be selected, and T is select time.