Adjustment device, method, and computer program for a brainwave identification system
In a system having an interface which utilizes an electroencephalogram, device operations which are not intended by the user are reduced. An adjustment apparatus for an electroencephalogram distinction method is used for an electroencephalogram interface system. The system has a biological signal measurement section for acquiring an electroencephalogram signal from a user, and an electroencephalogram interface section for presenting via an output section a plurality of menu items of the manipulation menu in a regular order, distinguishing by a previously determined distinction method a component of an event-related potential which is contained in the electroencephalogram signal after each menu item is highlighted, and operating a device based on the distinguished event-related potential. The adjustment apparatus includes: an analysis section for determining a gradient of a waveform of the event-related potential before the menu item is highlighted; and a determination section for comparing the gradient of the waveform as determined by the analysis section against a threshold value, and determining that the menu item corresponding to the gradient is a menu item which the user wishes to select based on a result of comparison.
1. An adjustment apparatus for use in an electroencephalogram interface system, the 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 a plurality of menu items of the manipulation menu in a regular order, distinguishing by a previously determined distinction method 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 adjustment apparatus adjusting the distinction method in the electroencephalogram interface section, wherein
the distinction method is a method of distinguishing the component of the event-related potential depending on whether the electroencephalogram signal satisfies a predetermined criterion or not,
the adjustment apparatus for the electroencephalogram distinction method comprising:
an analysis section for determining a gradient of a waveform of the event-related potential before the menu item is highlighted; and
a determination section for comparing the gradient of the waveform as determined by the analysis section against a threshold value, and determining that the menu item corresponding to the gradient is a menu item which the user wishes to select based on a result of comparison.
2. The adjustment apparatus of claim 1 , wherein, if the gradient of the waveform determined by the analysis section is smaller than a predetermined negative threshold value, the determination section determines that the menu item corresponding to the gradient is the menu item which the user wishes to select, and instructs the electroencephalogram interface section to operate the device based on the result of determination.
3. The adjustment apparatus of claim 1 , wherein, when determining that the menu item corresponding to the gradient is the menu item which the user wishes to select, the determination section instructs the electroencephalogram interface section not to perform distinction of the component of the event-related potential which is contained in the electroencephalogram signal after the menu item is highlighted.
4. The adjustment apparatus of claim 2 , wherein the determination section obtains the gradient of the waveform by dividing the event-related potential (μV) by time (s), and compares the gradient against the negative threshold value, the negative threshold value being −4.
5. The adjustment apparatus of claim 2 , wherein,
if the gradient of the waveform determined by the analysis section is greater than the predetermined negative threshold value, the determination section does not give any instruction to the electroencephalogram interface section; and
the electroencephalogram interface section distinguishes the component of the event-related potential which is contained in the electroencephalogram signal after each menu item is highlighted.
6. The adjustment apparatus of claim 2 , wherein,
the analysis section acquires information t representing a time interval of highlighting from the electroencephalogram interface section, and cuts out a waveform of the event-related potential from point t2 until point t1, such that point t1 is a point where the menu item is highlighted and point t2 is earlier than point t1 by a predetermined time.
7. The adjustment apparatus of claim 6 , wherein the analysis section employs a least-squares method to determine the gradient of the waveform of the event-related potential having been cut out.
8. A method used for adjusting a distinction method in an electroencephalogram interface system, the 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 a plurality of menu items of the manipulation menu in a regular order, distinguishing by a previously determined distinction method 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 adjustment method adjusting the distinction method in the electroencephalogram interface section, wherein
the distinction method is a method of distinguishing the component of the event-related potential depending on whether the electroencephalogram signal satisfies a predetermined criterion or not,
the adjustment method comprising the steps of:
determining a gradient of a waveform of the event-related potential before the menu item is highlighted; and
comparing the gradient of the waveform as determined by the step of determining a gradient against a threshold value, and determining that the menu item corresponding to the gradient is a menu item which the user wishes to select based on a result of comparison.
9. A non-transitory computer readable medium storing executable code in an electroencephalogram interface system, the 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 a plurality of menu items of the manipulation menu in a regular order, distinguishing by a previously determined distinction method 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 executable code when executed adjusting the distinction method in the electroencephalogram interface section, wherein
the distinction method is a method of distinguishing the component of the event-related potential depending on whether the electroencephalogram signal satisfies a predetermined criterion or not,
the executable code when executed causing the electroencephalogram interface system to execute the steps of:
determining a gradient of a waveform of the event-related potential before the menu item is highlighted; and
comparing the gradient of the waveform as determined by the step of determining a gradient against a threshold value, and determining that the menu item corresponding to the gradient is a menu item which the user wishes to select based on a result of comparison.