Device and Method For Deciding Necessity Of Brainwave Identification

• US 20090270753A1
• Filed: 03/13/2008
• Published: 10/29/2009
• Est. Priority Date: 03/28/2007
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Morikawa, Koji, Adachi, Shinobu
• Granted Patent: US 8,126,541 B2
• Time in Patent Office: Days
• US Class Current: 600/544
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: G06F 3/015 Input arrangements based on nervous system activity detection, e.g. brain waves [EEG] detection, electromyograms [EMG] detection, electrodermal response detection

Abstract

In a system having an interface which utilizes electroencephalogram, it is determined whether the user was looking at a menu or not based on the frequency of the user electroencephalogram, and the electroencephalogram is excluded from the subject of distinction in the case where the user is not looking at the menu.

A distinction necessity determination apparatus 10 for determining whether or not to perform a distinction of an electroencephalogram signal in an electroencephalogram interface system 1 includes a frequency analysis section 11 for calculating a representative frequency at which frequency power of the electroencephalogram signal becomes maximal, and a determination section 12. Based on a relative quantity between the switching frequency of menu items and the representative frequency of the electroencephalogram signal, the determination section 12 determines whether the representative frequency is related to switching of the menu items or not, and based on the result of determination, outputs to an electroencephalogram interface section 100 an instruction to adjust the distinction method for the electroencephalogram signal to be adopted in the electroencephalogram interface section 100.

Claims

1. An apparatus in an electroencephalogram interface system, the system having

an output section for visually presenting a manipulation menu for a device,

a biological signal measurement section for acquiring an electroencephalogram signal from a user, and

an electroencephalogram interface section for presenting via the output section menu items of the manipulation menu with a specific switching frequency, distinguishing based on the electroencephalogram signal preliminarily held a component of an event-related potential which is contained in the electroencephalogram signal after each menu item is highlighted, and operating the device based on the distinguished event-related potential,

the apparatus for adjusting a distinction method for the electroencephalogram signal to be adopted in the electroencephalogram interface section, comprising:

a frequency analysis section for calculating as a representative frequency at which a frequency power of the electroencephalogram signal becomes maximal; and

a determination section for, based on a relative quantity between the switching frequency of the menu items and the representative frequency of the electroencephalogram signal, determining whether the representative frequency is related to switching of the menu items or not, and in accordance with the result of determination, outputting to the electroencephalogram interface section an instruction to adjust the distinction method for the electroencephalogram signal to be adopted in the electroencephalogram interface section.

2. The apparatus of claim 1, wherein,

the determination section

instructs the electroencephalogram interface section to adopt the electroencephalogram signal as subject of distinction when the representative frequency is determined as being related to switching of the menu items,

and instructs the electroencephalogram interface section to exclude the electroencephalogram signal from the subject of distinction when the representative frequency is determined as not being related to switching of the menu items.

3. The apparatus of claim 1, wherein, based on a difference between the switching frequency of menu items and the representative frequency of the electroencephalogram signal, or a ratio between the switching frequency of menu items and the representative frequency of the electroencephalogram signal, the determination section determines whether the representative frequency is related to switching of the menu items or not.

4. The apparatus of claim 1, wherein the frequency analysis section calculates the representative frequency based on an electroencephalogram signal acquired at or after a point in time which is a predetermined number of seconds before a point of highlighting each menu item.

5. The apparatus of claim 1, wherein, as the representative frequency, the frequency analysis section calculates a frequency at which the frequency power becomes largest in a predetermined frequency band containing the switching frequency of menu items.

6. The apparatus of claim 1, wherein, as the representative frequency, the frequency analysis section calculates a frequency at which the frequency power becomes largest in a frequency band of 0.5 Hz or above.

7. The apparatus of claim 6, wherein the determination section determines whether the representative frequency is related to switching of the menu items or not based on a relative quantity of the switching frequency being selected from a frequency band of 0.5 Hz to 9 Hz and the representative frequency of the electroencephalogram signal.

8. The apparatus of claim 7, wherein the determination section determines that the representative frequency is not related to switching of the menu items when a difference between the switching frequency of menu items and the representative frequency of the electroencephalogram signal is 0.2 Hz or more.

9. The apparatus of claim 1, wherein, when the determination section instructs the electroencephalogram interface section to exclude the electroencephalogram signal from the subject of distinction, the electroencephalogram interface section sets back an operating state of the device by one.

10. The apparatus of claim 1, wherein,

when the electroencephalogram interface section presents menu items of a plurality of kinds of manipulation menus at a plurality of respectively different switching frequencies,

the determination section determines whether or not the representative frequency is related to the switching of any one of the menu items of the manipulation menus based on a relative quantity between each of the plurality of switching frequencies and the representative frequency of the electroencephalogram signal.

11. The apparatus of claim 10, wherein the determination section determines whether or not the representative frequency is related to the switching of any one of the menu items of the manipulation menus based on a relative quantity between each of the plurality of switching frequencies being set so as not to be integer multiples of one another and the representative frequency of the electroencephalogram signal.

12. The apparatus of claim 10, wherein the determination section identifies a switching frequency corresponding to a smallest relative quantity among relative quantities between the plurality of switching frequencies and the representative frequency of the electroencephalogram signal, and determines whether or not the representative frequency is related to switching of the menu items presented at the identified switching frequency.

13. The apparatus of claim 12, wherein,

the determination section retains a threshold value corresponding to each of the plurality of switching frequencies;

and

the determination section determines that the representative frequency is related to switching of the menu items presented at the identified switching frequency when the smallest relative quantity is smaller than the threshold value corresponding to the identified switching frequency, and determines that the representative frequency is not related to switching of the menu items presented at the identified switching frequency when the smallest relative quantity is equal to or greater than the threshold value corresponding to the identified switching frequency.

14. The apparatus of claim 1, wherein,

the electroencephalogram interface section retains a threshold value for distinguishing whether a P3 component is contained in the event-related potential contained in the electroencephalogram signal after each menu item is highlighted;

and

when it is determined that the representative frequency is not related to switching of the menu items, the determination section changes the size of the threshold value in a direction such that the P3 component of the event-related potential becomes less likely to be detected.

15. In an electroencephalogram interface system having an output section for visually presenting a manipulation menu for a device,

a biological signal measurement section for acquiring an electroencephalogram signal from a user, and

an electroencephalogram interface section for presenting via the output section menu items of the manipulation menu with a specific switching frequency, distinguishing based on the electroencephalogram signal preliminarily held a component of an event-related potential which is contained in the electroencephalogram signal after each menu item is highlighted, and operating the device based on the distinguished event-related potential,

a distinction necessity determination method for determining whether or not to allow the electroencephalogram interface section to perform a distinction of the electroencephalogram signal, comprising the steps of:

calculating as a representative frequency at which a frequency power of the electroencephalogram signal becomes maximal; and

determining whether the representative frequency is related to switching of the menu items or not, based on a relative quantity between the switching frequency of the menu items and the representative frequency of the electroencephalogram signal;

instructing, when it is determined as being related, the electroencephalogram interface section to adopt the electroencephalogram signal as subject of distinction; and

instructing, when it is determined as not being related, the electroencephalogram interface section to exclude the electroencephalogram signal from the subject of distinction.

16. The distinction necessity determination method of claim 15, wherein,

when the electroencephalogram interface section presents menu items of a plurality of kinds of manipulation menus at a plurality of respectively different switching frequencies,

the determining step determines whether or not the representative frequency is related to the switching of the menu items of the manipulation menus based on a relative quantity between each of the plurality of switching frequencies and the representative frequency of the electroencephalogram signal.

17. The distinction necessity determination method of claim 16, wherein the determining step identifies a switching frequency corresponding to a smallest relative quantity among relative quantities between the plurality of switching frequencies and the representative frequency of the electroencephalogram signal, and determines whether the representative frequency is related to switching of the menu items presented at the identified switching frequency.

18. The distinction necessity determination method of claim 17, further comprising a step of providing a threshold value for each of the plurality of switching frequencies, wherein,

the determining step determines that the representative frequency is related to switching of the menu items presented at the identified switching frequency when the smallest relative quantity is smaller than the threshold value corresponding to the identified switching frequency, and determines that the representative frequency is not related to switching of the menu items presented at the identified switching frequency when the smallest relative quantity is equal to or greater than the threshold value corresponding to the identified switching frequency.

19. An apparatus in an electroencephalogram interface system, the system having

an output section for visually presenting a manipulation menu for a device,

a biological signal measurement section for acquiring an electroencephalogram signal from a user, and

an electroencephalogram interface section for presenting via the output section menu items of the manipulation menu with a specific switching frequency, distinguishing based on the prestored electroencephalogram signal a component of an event-related potential which is contained in the electroencephalogram signal after each menu item is highlighted, and operating the device based on the distinguished event-related potential,

the apparatus for adjusting a distinction method for the electroencephalogram signal to be adopted in the electroencephalogram interface section, comprising:

a frequency analysis section for calculating as a representative frequency at which a frequency power of the electroencephalogram signal becomes maximal; and

a determination section for, based on a relative quantity between the switching frequency of menu items and the representative frequency of the electroencephalogram signal, determining whether the representative frequency is related to switching of the menu items or not, judging that the user is looking at the menu item when the representative frequency is determined as being related and judging that the user is not looking at the menu item when the representative frequency is determined as not being related, and adjusting the distinction method of the electroencephalogram interface section for the electroencephalogram signal in accordance with the result of determination.