JPH10137228A - Mental stress judging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To objectively and accurately judge mental stress even when a subject has irregular pulses or the like. SOLUTION: While applying temporary stress through a task/rest presenter 11, a heartbeat correspondent data sampling device 21 measures the pulsing signal of the subject and an RRI detection circuit 22 detects the RRI of pulsing intervals. A sympathetic nerve/parasympathetic nerve activity degree calculation circuit 24 finds a distribution area intask state and rest state expressed on a two-dimensional plane by calculating the degree of diffusion in RRI data, and a mental stress judging circuit 14 judges the presence/absence of mental stress from the position of that judgment area. When there are defective data caused by irregular pulses in heartbeat correspondent data during this operation, such a section is skipped by a defective data removal circuit 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mental stress determination device for determining mental stress as a constant stress of a person.

[0002]

2. Description of the Related Art Conventionally, there is a stress level measuring apparatus for measuring a stress level of a person by measuring a fluctuation state of pulse data by a microcomputer. As shown in FIG. 21, a pulse wave detector 501 for detecting a subject's pulse wave is connected to a pulse counter 502, and the pulse counter 502 is connected to a microcomputer 503. Then, as shown in FIG. 22, the pulse wave data detected by the pulse wave
The pulse data is converted into a shaped pulse according to 2 and the pulse data is counted.
The level of the stress is measured by monitoring the data. A similar one is described in JP-A-4-180730.

[0003]

In recent years, people have been subjected to various stresses at work or in daily life. In particular, due to rapid OA (office automation) and FA (factory automation), VDT (video display terminal) work and monitoring work are increasing, and mental stress caused by these work is a cause of overwork and human error. I have. In order to prevent this, it is important to evaluate and determine mental stress (also called techno stress).

[0004] However, the conventional stress level measuring device is configured to use only information on the rise and fall of the heart rate, so that the reliability of the stress level measurement is low, and
Only temporary stress at the time of measurement can be measured, and the reliability of stationary stress level measurement is low. Also,
When a phenomenon such as an arrhythmia occurs in the electrocardiogram signal, the section cannot be analyzed. Since only one biological signal called a pulse is used, there is a problem in that the determination itself becomes impossible when such an unanalyzable section occurs.

[0005] Then, taking advantage of the high correlation between mental stress and the autonomic nervous system, it is attempted to determine the activity of the autonomic nervous system by calculating the pulsation interval RRI in the electrocardiogram signal as shown in FIG. There is an attempt to do. At this time, if the electrical noise N is mixed in the electrocardiogram signal as shown in FIG. 24B, it is possible to deal with it by filtering processing. However, as shown in FIG. 2A, the rhythm of the pulsation such as an extrasystole due to arrhythmia is disturbed in the electrocardiogram signal.
In particular, when the pulsation missing K occurs, a great error occurs in the RRI detection. Many subjects who have arrhythmia in a mental stress state have been reported. Therefore, if the arrhythmia makes the analysis practically impossible, it cannot contribute to the original mental stress determination.

As described above, it can be said that a technique for objectively measuring the amount of sensation, that is, mental stress, and for quantitatively and highly reliable evaluation have not been established at present. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and has as its object to provide a mental stress determination device that objectively and accurately determines mental stress as stationary stress even when arrhythmia or the like occurs.

[0007]

Therefore, the present invention provides a task presenting means for temporarily applying stress to a subject, a heart rate equivalent data collecting means for collecting heart rate equivalent data of the subject, and a heart rate equivalent data collecting means. Pulsation interval detection means for detecting a pulsation interval based on the collected heartbeat equivalent data; and sympathetic parasympathetic nervous activity for calculating a sympathetic parasympathetic activity based on the pulsation interval data detected by the pulsation interval detection means. Degree calculating means, a defect data removing means for detecting a temporary abnormal pulsation, and removing the abnormal pulsation interval data from the processing target of the sympathetic parasympathetic activity calculating means, and a sympathetic parasympathetic activity calculating means And a mental stress determining means for determining a mental stress based on the sympathetic parasympathetic activity calculated by the above.

[0008] The above-mentioned mental stress judging means observes a change in a subject's response accompanying the task execution based on the sympathetic and parasympathetic nervous activity of the same subject based on heartbeat-equivalent data collected at a plurality of different times. Thus, the mental stress can be determined. Preferably, the task presentation means includes a timer, and the timer presents the time so that the task and the rest for a predetermined time are alternately performed for the subject.

Further, the sympathetic / parasympathetic nerve activity calculating means calculates a normalized variance and an average heart rate from the beat interval data detected by the beat interval detecting means, and calculates the normalized variance and the average heart rate. A task state distribution area and a rest state distribution area are respectively obtained on a two-dimensional plane, and the mental stress determination means calculates a mental stress based on an overlapping ratio of the area between the task state distribution area and the rest state distribution area. It can be determined. At this time, the mental stress determination means determines a change in mental stress from a temporal change in a distance between the center of gravity of the distribution area area representing the task state and the center of gravity of the distribution area area representing the rest state in the previous measurement and the current measurement. Can also.

Further, the means for calculating the sympathetic / parasympathetic nervous activity comprises:
The frequency of the beat interval data detected by the beat interval detecting means can be analyzed to calculate the parasympathetic nerve activity.

Further, it is preferable that the apparatus further comprises means for analyzing the frequency of brain waves of the subject, and the mental stress determining means further subdivides the mental stress based on the sympathetic and parasympathetic nerve activity with reference to the analysis result of the frequency analyzing means. desirable. The frequency analysis means, an electroencephalogram data collection means for collecting electroencephalogram data, a frequency component calculation circuit for calculating the frequency power of the electroencephalogram data cut out from each rest time zone, and the subject power by adding the power for each frequency component And a relaxation calculation circuit for obtaining the degree of relaxation.

[0012]

According to the mental stress determination device of the present invention, while giving a temporary stress to the subject by the task presenting means, the subject's heart rate equivalent data is collected by the heart rate equivalent data collecting means and input to the pulsation interval detecting means. The beat interval detecting means detects the beat interval and inputs the beat interval data to the sympathetic / parasympathetic activity calculating means. Based on the sympathetic parasympathetic activity calculated by the sympathetic parasympathetic activity calculating means, the presence or absence of mental stress is determined by the mental stress determining means. If there is a temporary abnormality in the beat interval detected by the beat interval detecting means, the abnormal beat interval data is not input to the sympathetic / parasympathetic nerve activity calculating means by the defect data removing means and is removed from the processing target. You.
Thereby, the sensory mental stress is objectively determined.

When the mental stress determination means determines the change in the subject's response accompanying the task based on the sympathetic and parasympathetic nervous activity of the same subject measured at a plurality of different times, The status of changes in stress at the time can be easily understood. Further, when the task presenting means presents a time by the timer so that the task and the rest for a fixed time are alternately performed to the subject, a simple task is given to the subject, and the heartbeat-equivalent data is provided. Easily collected.

The above-mentioned sympathetic / parasympathetic nervous activity calculating means obtains the distribution area of the normalized variance and the average heart rate, so that the mental stress judging means is healthy when there is no overlap and the distribution area overlaps. At some point, it can be determined that there is mental stress. In addition, by determining the temporal change of the distance between the centers of gravity of the distribution area areas representing the task state and the rest state in the previous measurement and the current measurement, it is possible to know the state of change in mental stress.

Further, the above-mentioned sympathetic / parasympathetic activity calculating means calculates the parasympathetic activity by frequency-analyzing the pulsation interval data detected by the pulsation interval detecting means, so that mental stress is objectively reduced. Is determined. Furthermore, the frequency power of the brain wave data cut out from the rest time zone is calculated with reference to the frequency analysis result of the brain wave,
The mental stress based on the sympathetic and parasympathetic nervous activity is further subdivided and determined with reference to the relaxation degree of the subject obtained by the addition, whereby a more detailed determination can be made.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to examples. FIG. 1 shows the configuration of the first embodiment, and FIG. 2 shows the state of use. FIG. 3 is a diagram showing a timing at which a task is given, FIG. 4 is a diagram showing the principle of measurement, and FIG. 5 is a diagram showing a part of a procedure for determining mental stress. Here, the sympathetic parasympathetic nervous activity is measured and calculated in a state where temporary stress is applied, and changes in the background with respect to steady stress are observed, and an electroencephalogram signal is also used when a phenomenon such as arrhythmia occurs. As a result, highly accurate determination can be performed without interruption of analysis.

The mental stress determination device 10 includes a task / rest presenter 11 as a task presenting means for giving a temporary stress to the subject, and a sympathetic parasympathetic activity calculating device for obtaining the sympathetic parasympathetic activity from the subject's heart rate equivalent data. 12, a frequency analysis device 13 for analyzing the frequency from the electroencephalogram data of the subject, and a mental stress determination circuit 14 connected to the sympathetic / parasympathetic nerve activity calculation device 12 and the frequency analysis device 13.

In the sympathetic parasympathetic nerve activity calculating device 12, the heartbeat-equivalent data collecting device 21 as a heartbeat-equivalent data collecting means for collecting heartbeat-equivalent data from the subject is provided with a RRI (R-R interval) which is a time interval of the pulsation. A sympathetic / parasympathetic nerve activity calculating circuit 2 which is connected to the RRI detecting circuit 22 for detecting data by wire or wirelessly and which calculates the sympathetic / parasympathetic nerve activity.
4 is connected. A defect data removing circuit 23 is provided between the RRI detecting circuit 22 and the sympathetic parasympathetic nerve activity calculating circuit 24. A sympathetic parasympathetic activity calculating circuit 24 is connected to the mental stress determining circuit 14 for determining mental stress.

On the other hand, the frequency analysis device 13 includes an electroencephalogram data collection device 31 for collecting electroencephalogram data of a subject, and a frequency component analysis circuit 32 for analyzing a frequency component of the electroencephalogram data.
And a relaxation calculation circuit 33 for adding the power of the frequency component of a predetermined sample at the time of rest to obtain a degree of relaxation. The output of the relaxation calculation circuit 33 is input to the mental stress determination circuit 14. Here, an RRI detection circuit 22, a defect data removal circuit 23, a sympathetic parasympathetic activity calculation circuit 24,
Frequency component analysis circuit 32, relaxation calculation circuit 3
3 and the mental stress determination circuit 14 are configured by a computer.

Then, the subject's pulsation signal R-wave is measured by the heartbeat-equivalent data collection device 21 as shown in FIG. Input to the RRI detection circuit 22. RRI detection circuit 22 to which the beat signal is input
Has a band-pass filter, detects RRI data from heartbeat-equivalent data, and outputs it to the sympathetic / parasympathetic nerve activity calculating circuit 24, as shown in FIG. 4B. During this time, if the heartbeat-equivalent data includes defect data due to arrhythmia or the like, RRI data based on the data is skipped by the defect data removal circuit 23.

The sympathetic parasympathetic activity calculating circuit 24 to which the RRI data has been input calculates the degree of variation of the RRI data, and obtains data in a task state and a rest state on a two-dimensional plane as shown in FIG. . As will be described in detail later, both data are separated as shown in (a) in a healthy person under non-mental stress, and overlap as shown in (b) in a person requiring attention under mental stress.

The frequency analyzer 13 obtains a frequency power spectrum of the brain wave data at rest. As will be described later, the mental stress determination circuit 14 determines the presence or absence of mental stress that is a steady stress from the position of each distribution area in the task state or the rest state on the two-dimensional plane. , With reference to the above frequency power spectrum.

Next, the flow of operation in this embodiment will be described in more detail. First, basic operations from the presentation of tasks / rests to the calculation of sympathetic parasympathetic nervous activity will be described with reference to FIGS. In step 110, a timer built into the task / rest presenter 11 presents the subject with the timing of repeating the task (task) and the rest (rest) for a certain period of time. Specifically, as shown in FIG. 3, the task is set to about 1 minute and the rest is set to about 2 minutes, and the task and the rest are alternately and repeatedly presented a plurality of times. The task may be any content that can apply mental stress. For example, as shown in FIG.
The task of writing as many circles 108 as possible on the predetermined paper 106 on which the entry position 107B is specified by the ruled line 107A within the above-mentioned predetermined time is imposed.

Returning to FIG. 6, in step 111, the heartbeat of the subject is measured by the heartbeat-equivalent data collection device 21, and a pulsation signal is collected as heartbeat-equivalent data. The pulsation signal is sampled at 100 Hz or more by the RRI detection circuit 22 and sequentially taken in. In the case of an electrocardiogram signal, an electrode needs to be attached to the body. However, in this case, since a task in which the subject does not move much is assumed, no problem occurs in measuring the heart rate. In addition, since accurate waveform diagnosis for medical use is not the purpose, it is possible to apply an electrode that is easily mounted, for example, a bee-shaped one as shown in FIG. Furthermore, the same effect can be obtained with an optically measured pulse wave signal and a pulse wave signal obtained by pressure measurement, which can be easily measured, as long as the pulse timing can be detected by appropriate signal processing.

Next, in step 112, an undesired signal such as noise is removed by a band pass filter in the RRI detection circuit 22, and a heartbeat equivalent signal is subjected to filing processing. In step 113, the heartbeat-equivalent signal is subjected to threshold processing or the like, and in step 114, RRI data (R-R interval), which is the time interval of the beat, is detected. However, since RRI originally involves fluctuations,
Although the RI data must be irregularly sampled in a time series, if necessary, it is also possible to perform regular sampling in a time series by an interpolation process.

In step 115, the defect data removing circuit 23 checks whether the time interval between beats is within a predetermined range. Here, the new data RR
Upon detecting I (1), the data RRI (0) immediately before is detected, and (1/2) RRI (0) to (3/2) RRI are referred to.
The range of (0) is set as the detection range. If the pulsation is lacking due to arrhythmia, the RRI will be about twice as large as usual, and can be detected by this check. That is, when the RRI (1) is within the above range, the sympathetic parasympathetic nerve activity calculating circuit 2
4 is sent to the next step 117, but when it is not within the above range, it is not sent to the sympathetic / parasympathetic nervous activity calculating circuit 24 as a value including an error, and only the time information is updated in step 116. Then, the process proceeds to step 117.

The settings from (1/2) to (3/2)
Mental tasks rely on no more than 50% instantaneous change. The arrhythmia in a subject living a normal life returns to the normal pulsation even if the phenomenon occurs, and the subsequent pulsation can be used again for determination.

In the sympathetic parasympathetic activity calculating circuit 24,
The degree of variation in the RRI data is calculated. It has been experimentally confirmed that the degree of variation in the RRI data has a close correlation with the sympathetic parasympathetic nervous activity. here,
The variance is used as an index representing this variation. First, in step 117, data of about 15 seconds (in this embodiment, 16 samples) is cut out from the sequentially input RRI data as an analysis section. Next, step 118
Then, the normalized variance RRV and the average heart rate BEAT are calculated,
These are stored as time data of the median of the analysis section.

Next, in step 119, it is determined whether the time data of the median of the analysis section is data in the task state or data in the rest state. In the case of the task state, in step 120, the data is accumulated as the task state data, and the normalized variance RRV and the average heart rate BEA according to the task state are stored.
The relationship with T is obtained as an area on a two-dimensional plane, and the center of gravity and the standard deviation are calculated.

Next, the routine proceeds to step 122, where it is checked whether presentation of the task and the rest is completed. If the presentation of the task and the rest has not been completed, the process proceeds to step 123, and the process of steps 117 to 119 is repeated after shifting the analysis section by one point width. Here, the shift of the analysis section by one point width is represented by R
This is because, when analyzing the RI data in a time series, it is possible to analyze the data in the most detailed manner each time it is input.

On the other hand, in the case of the rest state in step 119, the process proceeds to step 121, where the data is accumulated as the rest state data, and the relationship between the normalized variance RRV according to the rest state and the average heart rate BEAT is represented on a two-dimensional plane. In addition to calculating the area, the center of gravity and the standard deviation are calculated. Next, the routine proceeds to step 122, where it is checked whether the presentation of the task and the rest is completed. If the presentation of the task and the rest has not been completed, the process proceeds to step 123 again, shifts the analysis section by one point width, and repeats the processing of steps 117 to 119. The processing of steps 117 to 123 is repeated while the task and the rest are presented to the subject.

Next, when the completion of presentation of the task and the rest is checked in step 122,
Proceeding to 4, the mental stress determination circuit 14 determines the mental stress by comparing the distribution areas on the normalized variance RRV-average heart rate BEAT two-dimensional plane.

Next, the operation of the frequency analyzer 13 will be described with reference to FIG. In step 201, first, in step 201, the repetition timing of the task and the rest in step 110 is presented to the subject.
As a result, spontaneous brain waves are collected by monopolar induction from the subject's forehead and the like, and are taken into the frequency component analysis circuit 32 by sampling at 1 kHz or more. After that, the frequency component analysis circuit 32 performs filtering for removing the undesired signal in step 202, and in step 203, cuts out a 50% middle portion during rest. In this way, cut-out electroencephalogram data is obtained in step 204.

In step 205, a frequency power spectrum is calculated for the cut-out electroencephalogram data.
A power spectrum is obtained for each frequency band as shown in FIG.
These are added in step 206 respectively. The same processing is repeated until the rest state ends by the task / rest presentation completion determination check in the next step 207. When the task / rest presentation is completed, the power spectrum addition value for each frequency band is determined in step 208 by the mental stress determination circuit 14. To be used as a reference for the judgment.

Next, the judgment in the mental stress judgment circuit 14 will be described. FIG. 11 shows the normalized variance RRV.
FIG. 6 is a diagram showing a relationship between the average heart rate BEAT and the average heart rate BEAT on the horizontal axis. Then, the normalized variance RRV indicates that the burden increases as the average heart rate BEAT increases as going to the left. Basically, a healthy person has a clear difference in response between when stress is applied and when it is not.

That is, under non-mental stress, the distribution areas of the task state and the rest state are distributed at positions separated from each other. And if you are performing the task correctly,
As a result, the distribution area of the task state is located at the upper left where the burden is higher than the distribution area of the rest state. this is,
This is a normal response considering the activity of the sympathetic parasympathetic nerve. On the other hand, in a state under mental stress, which is a background stress, a phenomenon of non-concentration in the task state and non-relaxation in the rest state occurs, and the mutual distribution areas approach each other.

FIGS. 12 and 13 show the measurement results of subject A and subject B, respectively. FIGS. 12 (a) and 13 (a) show the results of FIG. b) and (b) of FIG. 13 show the results measured under a mental stress condition. In each of the figures, under the non-mental stress state, the distribution areas of the task state and the rest state are located at separate positions, and under the mental stress state, the respective distribution areas are in an overlapping state.

FIG. 14 is a flowchart showing a determination algorithm when there is no previous data. Here RR
The determination is first made by comparing the distribution areas on the V-BEAT two-dimensional plane. In particular, the above-mentioned phenomenon is grasped based on the area of the distribution area of the task state as a reference and the overlapping rate.

First, in step 130, the previous step 12
The center of gravity and the standard deviation at the time of the task and at the time of the rest obtained at 0 and 121 are Gt (Rt, Bt) and St, respectively.
(Rt, Bt), Gr (Rr, Br) and Sr (R
(r, Br), the relative position of the center of gravity of the distribution area of the task state and the rest state on the two-dimensional plane is determined. That is, in the RRV axis direction, whether or not the center of gravity position Rt in the task state is on the left side of the center of gravity position Rr in the rest state in the drawing, and in the BEAT axis direction,
It is checked whether the center of gravity position Bt in the task state is above the center of gravity position Br in the rest state in the figure, and the center of gravity position relationship is determined.

The center of gravity position Rt is to the left of the center of gravity position Rr (Rt <Rr), and the center of gravity position Bt is the center of gravity position B
If it is above r (Bt> Br), step 131
Proceed to. On the other hand, when the relationship between the center of gravity positions of the task state and the rest state does not satisfy Rt <Rr and Bt> Br, the process proceeds to step 132. In this case, it is necessary to measure again because the possibility of task default is high.

In step 131, the areas At and Ar of the distribution areas of the task state and the rest state are calculated, respectively. Thereafter, in step 133, the presence / absence of mental stress is determined based on the overlap ratio of the area area (At & Ar) where the distribution area At of the task state overlaps the distribution area area Ar of the rest state with respect to the distribution area area At in the task state. .

Then, as shown in FIG. 15A, when the distribution area of the task state and the distribution area of the rest state do not overlap ((At & Ar) = 0), step 134 is executed.
Thus, the determination of "no mental stress" is made, and the person is determined to be a healthy person. Also, as shown in FIG. 15B, when the overlapping ratio of the distribution area of the rest state to the distribution area of the task state is equal to or less than １ ／ ((At & Ar) ≦ At).
/ 2) In step 135, a determination is made that “there is a possibility of mental stress”. Further, as shown in FIG. 15C, when the above-mentioned overlap ratio is 1/2 or more ((A
t &Ar)> At / 2) is classified as (with mental stress).

When (mental stress is present), the process proceeds to step 136, where the power spectrum for each frequency component calculated in step 208 is referred to.
That is, in step 136, the power P (α) of the α wave which is a rest component and the power P (β) of the β wave which is an awakening component are compared. FIG. 16 shows the EEG data frequency power spectrum at the time of the task and at the time of the rest. This power spectrum is calculated from the electroencephalogram collected while resting the eyes on rest at rest. As can be seen from the figure, it can be confirmed that in the transfer of the frequency spectrum when the rest is approximately one minute, the task is one minute, and the rest is one minute along the time axis, the low frequency components become prominent at the time of rest.

Thus, when the power P (β) of the arousal component is sufficiently large (about twice or more) with respect to the power P (α) of the rest component, data supporting the case where the user cannot relax at rest even during mental stress can be obtained. Thought,
At step 137, a determination is made that "there is mental stress and cannot be relaxed". Usually, there are many cases in which the worker cannot relax at the time of the mental stress in the worker, and is referred to as a so-called “type A”. On the other hand, the power P (α) of the rest component is the power P of the awakening component.
(Β) If the person is relaxed at rest while being superior, and is determined to be in a mental stress state, it is considered that he / she cannot concentrate on the task, and a determination of “with mental stress / impossible to concentrate” is made in step 138. .

FIG. 17 is a flowchart showing a determination algorithm when there is previous data. In this case, the determination is made based on the temporal change of the distance between the centers of gravity of the distribution areas. First, the center of gravity determined in the previous steps 110 to 123 is stored in step 148 as previous data. Gt1 (Rt1, Bt
1) Let the center of gravity of the rest be Gr1 (Rr1, Br1).
Next, in the same manner, in step 149, the task center of gravity is set to Gt2 (R
t2, Bt2) and the center of gravity of the rest are Gr2 (Rr2, Br2).
r2) is required.

In step 150, the relative position of the center of gravity of the distribution area of the task state and the rest state on the two-dimensional plane is determined. That is, in the RRV axis direction, whether or not the center of gravity Rt2 in the task state is to the left of the center of gravity Rr2 in the rest state, and in the BEAT axis direction, the center of gravity Bt2 in the task state is higher than the center of gravity Br2 in the rest state. Is checked to determine the center-of-gravity positional relationship.

The position of the center of gravity Rt2 is the position of the center of gravity Rr2.
If it is further to the left (Rt2 <Rr2) and the center of gravity Bt2 is above the center of gravity Br2 (Bt2> Br2), the process proceeds to step 151. On the other hand, the relationship between the center of gravity positions of the task state and the rest state is Rt2 <Rr2,
If Bt2> Br2 is not satisfied, step 15
Proceed to 2. In this case, measurement is performed again because the possibility of task default is high.

Next, at step 151, the distance between the centers of gravity (Gt1-Gr1) in the distribution area of the task state and the rest state measured last time, and the distance between the centers of gravity (Gt2-Gr2) in the distribution area of the task state and the rest state measured this time. ) Is calculated. Next, step 153
Then, by comparing the previous distance between the centers of gravity (Gt1-Gr1) with the current distance between the centers of gravity (Gt2-Gr2), a change in mental stress is determined.

Then, the distance between the centers of gravity measured this time (Gt2
-Gr2) is the distance between the centers of gravity (Gt1-Gr) measured last time.
(Gt1−Gr1) = (Gt2)
-Gr2)), in step 154, a determination is made of "mental stress, no change from previous time". When the distance between the centers of gravity (Gt2-Gr2) measured this time is larger than the distance between the centers of gravity (Gt1-Gr1) measured last time ((Gt1-Gr1) <(Gt2-Gr2)), in step 155, " Mental stress is on a downtrend from the previous survey "
Is determined. Furthermore, the distance between the centers of gravity (Gt2-Gr2) measured this time is the distance between the centers of gravity (Gt1
-Gr1) ((Gt1-Gr1)
1)> (Gt2-Gr2)), it is classified as (mental stress, increasing tendency from the previous time).

(Mental stress, increasing trend from the previous time)
When it becomes, the process proceeds to step 156 to refer to the power spectrum of each frequency component of the electroencephalogram as in the case where there is no previous data. The power P (β) of the β wave as a component is compared. When the power P (β) of the awakening component is sufficiently larger than the power P (α) of the resting component, step 157 is executed.
Then, the judgment of "mental stress, increasing tendency from previous time / impossible to relax" is made.

On the other hand, when the power P (α) of the rest component is superior to the power P (β) of the awakening component, step 1
At 58, a determination is made as to "mental stress, tendency to increase from previous time / inability to concentrate". Steps 111 to 114 above
Corresponds to steps 117 to 123
Sets the sympathetic parasympathetic activity calculating means in steps 130 to
138 and 150 to 158 constitute mental stress determination means.

As described above, according to the present embodiment,
In the RRV-BEAT two-dimensional distribution based on the RRI data, by determining the overlap ratio of the area area (At & Ar) where the task state distribution area At overlaps the rest state distribution area Ar with the task state distribution area At. The presence or absence of subjective mental stress can be objectively determined. At this time, the defect data removing circuit 23 uses only the time interval of the pulsation within the predetermined range with respect to the immediately preceding data as data, so that when the pulsation is lost due to arrhythmia, Also, a highly accurate determination is made. Further, the frequency analysis device 13 is provided to refer to the power spectrum of the EEG frequency component in the rest, and the state with mental stress is further classified into inability to relax or inability to concentrate. Evaluation is possible.

In determining the mental stress, when there is the previous determination data, the determination is made based on the temporal change of the distance between the centers of gravity of the distribution areas of the task state and the rest state. You can also know the status of changes. Further, if the distribution area is further displayed on the display, the overlapping state of the areas can be visually recognized, and the judgment can be easily understood intuitively.

FIGS. 18 and 19 show a second embodiment of the present invention. This embodiment is an example in which frequency analysis is used to calculate the degree of variation of RRI data in the sympathetic parasympathetic activity calculating circuit, and the other configuration is the same as that of the first embodiment. FIG. 18A shows a state in which regular sampling is performed on the RRI, and FIG. 18B is a diagram for explaining frequency analysis.

First, the RRI as the time interval of the pulsation shown in FIG. 4 is interpolated and regularly sampled, and as shown in FIG. A power curve of each sampled data is illustrated in FIG. Then, the power is separated into a high frequency component and a low frequency component at a predetermined frequency F0, which is 0.15 Hz in this embodiment. That is, the density function of the power spectrum obtained by performing the FFT processing on the power curve is S (f), the low frequency component is S (f) from 0 to F0, and the high frequency component is F (F).
It can be obtained by integrating from 0 to infinity, and its high frequency component reflects the activity of the parasympathetic nerve. An increase in power in a high frequency component indicates a relaxed state of the parasympathetic nerve, and a decrease in the power indicates a tension state of the parasympathetic nerve. The rise of the power in the low frequency component indicates the process of changing the parasympathetic nerve, and the fall indicates the steady process of the parasympathetic nerve.

FIG. 19 is a view showing the result of the frequency analysis, showing the power of the frequency component with respect to the experiment execution time (sec). As shown in the figure, the change amount of the high-frequency component 202 of the healthy subject is large and the change amount of the high-frequency component 203 of the subject in the mental stress state is small compared to the task execution portion 201, that is, the portion indicating the concentration state. . Therefore, it is possible to determine the mental stress based on the difference in the change amount of the high frequency component.

As described above, according to this embodiment, the RRI as the time interval of the subject's pulsation is interpolated and regularly sampled, and separated into a low frequency component and a high frequency component at a predetermined frequency. To perform frequency analysis. Since the high frequency component reflects the activity of the parasympathetic nerve, the state of mental stress can be objectively determined.

In each of the above embodiments, the task of writing a circle on a predetermined sheet has been exemplified as a task.
As shown in FIG. 7, when a circle 303 is entered in the same entry column 302 as in the first embodiment, a board 301 and a pen 304 capable of pen input are used for the computer 300, and the execution speed and error You can also perform tasks while controlling the rate. In this case, task and rest time and achievement level management become easy, and the task can be given more effectively. A method is also possible in which a computer forcibly performs work such as mental arithmetic while controlling the execution speed and the error rate with a computer. The task is applicable as long as the content can give a subject mental stress. At this time, the subject is forcibly performed within a range that does not give up.

[0059]

As described above, according to the mental stress determination apparatus of the present invention, while applying a temporary stress to the subject, the subject's heartbeat-equivalent data is collected and the beat interval is detected. In calculating the sympathetic parasympathetic activity based on the data, the sympathetic parasympathetic activity was calculated with temporary stress applied, and mental stress was determined by focusing on the change. A highly accurate objective judgment based on a physiological background can be performed for a stationary mental stress that can be evaluated only by subjective evaluation. A defect data removing means is provided so that when there is a temporary abnormality in the pulsation interval, the abnormal pulsation interval data is removed from the processing target. This has the effect of ensuring high accuracy of.

When the above-mentioned mental stress is determined based on the change in the subject's response accompanying the task execution based on the sympathetic and parasympathetic nervous activity of the same subject measured at a plurality of different times, the change in the mental stress is determined. The situation can be easily known, and the determination accuracy can be improved. In addition, when giving a task to a subject, a timer can provide a simple task to the subject by presenting the time so that the task and the rest for a fixed time are alternately performed. Equivalent data can be easily collected.

Further, by calculating the normalized variance and the average heart rate from the beat interval data and obtaining the two-dimensional distribution area, when there is an overlap between the distribution areas, there is a mental stress and the overlap of the areas is reduced. When there is no mental stress, it can be determined that there is no mental stress, so that an objective determination is easy. In addition, by determining the temporal change of the distance between the centers of gravity of the distribution areas of the task state and the rest state in the previous measurement and the current measurement, it is possible to know the state of change in mental stress, and to improve determination accuracy. it can. The mental stress can also be objectively determined by calculating the parasympathetic nervous activity by frequency analysis of the beat interval data.

Further, the frequency of the electroencephalogram is analyzed, and especially the frequency power of the electroencephalogram data cut out from the rest time zone is calculated and added. By referring to the relaxation degree of the subject obtained by adding, the mental stress based on the sympathetic parasympathetic nervous activity is obtained. Is further determined, a more detailed determination is made, so that a detailed measure can be taken.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a use state of the first embodiment.

FIG. 3 is a diagram showing a task presentation timing in the first embodiment.

FIG. 4 is a diagram for explaining a principle of measuring a heartbeat in the first embodiment.

FIG. 5 is a diagram illustrating a procedure for determining mental stress in the first embodiment.

FIG. 6 is a flowchart showing a basic operation flow from task / rest presentation to sympathetic / parasympathetic nervous activity calculation in the first embodiment.

FIG. 7 is a flowchart showing a basic operation flow from task / rest presentation to sympathetic / parasympathetic nervous activity calculation in the first embodiment.

FIG. 8 is a diagram illustrating tasks in the first embodiment.

FIG. 9 is a flowchart illustrating a flow of a frequency component analysis of an electroencephalogram according to the first embodiment.

FIG. 10 is an explanatory diagram showing a procedure for adding an electroencephalogram power spectrum for each frequency band.

FIG. 11 is a diagram for explaining the principle of determining mental stress in the first embodiment.

FIG. 12 is a diagram for explaining the change in the two-dimensional distribution of the normalized heartbeat rate and the average heart rate according to the presence or absence of mental stress.

FIG. 13 is a diagram for explaining a change in the two-dimensional distribution of the normalized heart rate and the average heart rate according to the presence or absence of mental stress.

FIG. 14 is a flowchart illustrating a determination algorithm when there is no previous data.

FIG. 15 is a diagram showing an example of determining mental stress based on sympathetic parasympathetic nerve activity.

FIG. 16 is a diagram showing a frequency power spectrum of an electroencephalogram at the time of a task and at the time of rest.

FIG. 17 is a flowchart illustrating a determination algorithm when there is previous data.

FIG. 18 is a diagram illustrating the principle of determining mental stress in the second embodiment.

FIG. 19 is a diagram illustrating a procedure for determining mental stress in the second embodiment.

FIG. 20 is a diagram illustrating another example of a task.

FIG. 21 is a block diagram showing a configuration of a conventional stress level measuring device.

FIG. 22 is a diagram illustrating a measurement principle of a conventional stress level measurement device.

FIG. 23 is a diagram showing a beat interval in an electrocardiogram waveform.

FIG. 24 is a diagram showing an example of an electrocardiogram waveform including an abnormal state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Mental stress judging device 11 Task / rest presenter 12 Sympathetic parasympathetic activity calculating device 13 Frequency analyzer 14 Mental stress judging circuit 21 Heart rate equivalent data collecting device 22 RRI detecting circuit 23 Defect data removing circuit 24 Sympathetic parasympathetic activity calculating Circuit 31 EEG data sampling device 32 Frequency component analysis circuit 33 Relaxation calculation circuit 106 Paper 107A Ruled line 300 Computer 301 Board 302 Entry field 304 Pen

Claims (8)

[Claims] 1. A task presenting means for temporarily applying stress to a subject, a heart rate equivalent data collecting means for collecting heart rate equivalent data of the subject, and a pulsation based on the heart rate equivalent data collected by the heart rate equivalent data collecting means. Pulsation interval detecting means for detecting an interval, sympathetic parasympathetic activity calculating means for calculating sympathetic parasympathetic activity based on pulsation interval data detected by the pulsating interval detecting means, A defect data removing unit that detects an abnormality and removes the pulsation interval data of the abnormality from a processing target of the sympathetic parasympathetic activity calculating unit; and a sympathetic parasympathetic activity calculated by the sympathetic parasympathetic activity calculating unit. A mental stress determination unit for determining a mental stress based on the mental stress. 2. The mental stress judging means observes a change in a subject's response accompanying the task based on the sympathetic and parasympathetic nervous activity of the same subject based on heartbeat-equivalent data collected at a plurality of different times. By doing
The mental stress is determined.
The mental stress determination device described in the above. 3. The task presenting means includes a timer,
The mental stress determination device according to claim 1 or 2, wherein a time is presented by a timer so that the subject alternately performs a task and a rest for a predetermined time. 4. The sympathetic parasympathetic activity calculating means,
A normalized variance and an average heart rate are calculated from the beat interval data detected by the beat interval detecting means, and the normalized variance and the average heart rate are respectively calculated on the two-dimensional plane. 3. The mental stress determination unit according to claim 1, wherein the mental stress determination unit determines mental stress based on an overlapping ratio of areas of the task state distribution area and the rest state distribution area. 3. The mental stress determination device according to 3. 5. The sympathetic parasympathetic activity calculating means,
A normalized variance and an average heart rate are calculated from the beat interval data detected by the beat interval detecting means, and the normalized variance and the average heart rate are respectively calculated on the two-dimensional plane. Determined as a distribution area, the mental stress determination means determines the mental stress from the temporal change of the distance between the center of gravity of the distribution area area representing the task state and the center of gravity of the distribution area area representing the rest state in the previous measurement and the current measurement. 4. The mental stress determination device according to claim 1, wherein the change is determined. 6. The sympathetic / parasympathetic nervous activity calculating means,
4. The mental stress determination device according to claim 1, wherein the parasympathetic nervous activity is calculated by frequency-analyzing the beat interval data detected by the beat interval detecting means. 7. It has a frequency analysis means of a subject's brain wave,
7. The mental stress determining unit according to claim 4, wherein the mental stress based on the sympathetic parasympathetic nervous activity is further subdivided with reference to an analysis result of the frequency analyzing unit. Mental stress judgment device. 8. An electroencephalogram data acquisition means for acquiring electroencephalogram data, a frequency component calculation circuit for calculating a frequency power of the electroencephalogram data cut out from each rest time zone, and a frequency component for each frequency component. 8. A relaxation calculating circuit for obtaining a degree of relaxation of the subject by adding.
The mental stress determination device described in the above.