JP2001198113A - Fatigue degree calculation device - Google Patents

Abstract

(57) [Summary] [Problem] To accurately calculate a fatigue degree. SOLUTION: The stress degree measuring device 12 is provided with a heart rate RR.
Measure the interval, 0.15-0.5Hz of heartbeat RR interval
Is analyzed, and the stress level is calculated based on the signal strength and an arithmetic expression indicating the relationship between the signal strength and the stress level stored in the memory. The arousal level measuring device 14
The blink speed is analyzed, and the degree of arousal is calculated based on the blink speed and an arithmetic expression indicating the relationship between the blink speed and the degree of arousal stored in the memory. The fatigue degree calculator 16 calculates the stress degree measured by the stress degree measuring unit 12 and the awakening degree measured by the awakening degree measuring unit 14, the stress degree stored in the fatigue degree calculating memory 18, the awakening degree, and the fatigue degree. And an arithmetic expression indicating the relationship with

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for calculating a degree of fatigue, and more particularly to a device for calculating a degree of fatigue using a physiological quantity relating to stress.

[0002]

2. Description of the Related Art Conventionally, there has been proposed an apparatus utilizing physiological data for objectively evaluating the stress of a human body. For example, Japanese Patent Application Laid-Open No. Hei 5-49626 discloses a method of measuring physiological information such as body sway, heartbeat, and brain waves as physiological data, performing an arithmetic process such as frequency analysis on the data, and combining the data with psychological data to obtain a stress level. (Human body distortion)
There is proposed a device which converts the scale into a scale and displays it, or instructs an operator according to the degree of stress. In this device, the stress level of the human body when an external stimulus (stresser) acts on the human body is evaluated based on the biological information related to the stress in the biological information. That is, basically, the degree of stress is evaluated using the increase and decrease of the physiological stress response.

Here, since accumulation of stress is basically a main factor causing fatigue, fatigue can be estimated by detecting stress. That is, when the evaluation subject actively and enthusiastically works on the given task, the correlation between the stress level and the fatigue level is high, and it is possible to estimate the fatigue from the magnitude of the stress.

[0004]

However, when the person to be evaluated shows an evasive action such as not making an effort according to the load, the perceived degree of fatigue does not increase even though the physiological stress itself does not increase. There is a divergence phenomenon that increases, and the estimation accuracy of fatigue is poor only by stress evaluation.
This is because awakening is involved together with stress as a factor that strongly affects the fatigue felt by the evaluation subject, and it is considered that these two factors affect fatigue while having an interaction.

In the above-mentioned apparatus (Japanese Patent Laid-Open No. 5-49626), a method is proposed in which physiological data and psychological data are used together. In this case, objective physiological data and subjective psychological data are mixed. And it is difficult to quantify those interactions.

The present invention has been made in view of the above-described circumstances, and has as its object to propose a fatigue degree calculating device capable of calculating a fatigue degree with high accuracy.

[0007]

In order to achieve the above object, the invention according to claim 1 comprises a stress level calculating means for calculating a stress level based on a physiological quantity related to stress, and an arousal level based on a physiological quantity related to arousal level. , A storage means for storing the stress level and the relationship between the arousal level and the fatigue level, and the stress level calculated by the stress level calculation means and the arousal level calculated by the wakefulness level calculation means. And a calculating means for calculating the fatigue level based on the relationship between the stress level and the arousal level and the fatigue level stored by the storage means.

[0008] That is, the stress degree calculating means of the fatigue degree calculating apparatus according to the present invention calculates the stress degree based on the physiological quantity relating to stress. Here, for example, humans take an active role when trying to achieve a goal or coping with a load. Generally, such an effort causes stress on the human body, which is perceived as fatigue.
In such a state, the degree of fatigue can be easily estimated from the degree of stress. However, when the load is further increased, the child may take an evasive action for self-defense without making an effort according to the load. In this case, although the load is increased and the feeling of fatigue itself is increased, the stress as a biological reaction is reduced, which may result in a “blurred state”. Therefore, the estimation accuracy of the fatigue level is poor only from the stress level. That is, as described above, not only stress but also arousal is involved as a factor that strongly affects the fatigue felt by the evaluation subject, and these two factors interact to affect fatigue. Therefore, the arousal level calculating means of the present invention calculates the arousal level as a factor that strongly affects fatigue based on the physiological quantity related to the arousal level.

Further, since the stress level and the arousal level have an interaction and affect the fatigue, the relationship between the stress level and the arousal level and the fatigue level can be quantitatively determined in advance. Thus, the storage means stores the relationship between the degree of stress and the degree of arousal and the degree of fatigue.

The calculating means calculates the stress level calculated by the stress calculating means and the alertness calculated by the alertness calculating means, and the stress level stored by the storage means and the relationship between the arousal level and the fatigue level. , The degree of fatigue is calculated.

As described above, according to the present invention, the degree of fatigue is calculated using the degree of stress and the degree of arousal. Therefore, even when the subject to be evaluated has a mixture of active behavior and avoidable behavior,
The degree of fatigue can be accurately calculated.

Here, in the present invention, there are provided first detecting means for detecting the physiological quantity relating to the stress, and second detecting means for detecting the physiological quantity relating to the arousal level. Calculating a stress level based on a physiological quantity related to the stress detected by the first detecting means, wherein the arousal degree calculating means calculates the arousal based on the physiological quantity related to the arousal level detected by the second detecting means The degree may be calculated.

Here, the physiological quantity relating to the stress is:
A second including a first frequency and less than the first frequency;
At least one of a component of a heartbeat and a stress hormone in a first frequency band not including the frequency of the first frequency band, wherein the physiological amount related to the arousal level does not include the first frequency and includes the second frequency. It is at least one of a heartbeat component, a blink state (blink speed and blink frequency), a skin potential, a skin resistance, and an eye open state within the frequency band of No. 2.

In the case where a heartbeat component in the first frequency band is used as the physiological quantity relating to the stress,
When the intensity of the heartbeat in the first frequency band is obtained, and the component of the heartbeat in the second frequency band is used as the physiological quantity related to the arousal level, the intensity of the heartbeat in the second frequency band is calculated. Ask. Note that the heartbeat intensity is an integrated value of the heartbeat component in the frequency band.

[0015] The stress hormone is at least one of adrenaline in urine and cortisol in saliva.

Further, the present invention includes heart rate detecting means for detecting a heart rate, wherein the stress degree calculating means includes a first frequency of the heart rate detected by the heart rate detecting means and is smaller than the first frequency. The stress level is calculated based on a component in a first frequency band not including a second frequency, and the arousal level calculation unit does not include the first frequency of the heartbeat detected by the heartbeat detection unit. And the second
The arousal level may be calculated based on a component in a second frequency band including the frequency of the arousal.

In this case, the stress level calculating means calculates the stress level based on the intensity of the heartbeat in the first frequency band, and the arousal level calculating means calculates the stress level in the second frequency band. The awakening degree is calculated based on the intensity of the awakening. Note that the heartbeat intensity is an integrated value of a heartbeat component in the frequency band.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, a fatigue degree calculating device according to the present embodiment is intended for a driver who drives a car, and a stress degree measuring device 12 that measures a stress degree based on a physiological amount related to the driver's stress.
The arousal level measuring device 14 that measures the arousal level based on the physiological quantity related to the arousal level of the driver, calculates the stress level and the fatigue level calculation formula (the equation showing each curve shown in FIG. 7) indicating the relationship between the arousal level and the fatigue level. The memory 18 for calculating the degree of fatigue stored, the degree of stress measured by the degree-of-fatigue measuring device 12 and the wakefulness measured by the wakefulness measuring device 14, and the memory 1 for calculating the degree of fatigue.
8, a fatigue degree calculator 16 for calculating the fatigue degree based on the fatigue degree calculation formula, a fatigue degree indicator 20 for displaying the fatigue degree calculated by the fatigue degree calculator 16, and a fatigue degree calculation. A warning indicator 22 for displaying a warning when the degree of fatigue calculated by the device 16 is equal to or more than a predetermined value.

As shown in FIG.
Is obtained from a heartbeat detection electrode 24 for detecting a heartbeat, and an electrical signal (see FIG. 4) representing the heartbeat detected by the heartbeat detection electrode 24.
A heart rate RR interval measuring device 26 for measuring an R interval (an R-wave interval of a heartbeat); a frequency band having a high correlation with the stress level of the heartbeat RR interval measured by the heart rate RR interval measuring device 26 (second A frequency analysis device 28 for analyzing the signal intensity of one frequency band, a memory 32 for storing an arithmetic expression indicating the relationship between the signal intensity and the stress level, and the frequency analysis device 2
8 is provided with a stress degree calculator 30 for calculating the stress degree based on the signal strength obtained by the analysis and the arithmetic expression stored in the memory 32.

As shown in FIG. 3, the arousal level measuring device 14 is disposed around the driver's eyeball as shown in FIG. 5, and detects the blinks by blink detection electrodes 34 (34A and 34B).
An electro-oculogram measuring device 36 and an electro-oculography measuring device 36 for converting an electric signal indicating a blink detected by the blink detecting electrode 34 into electric signal data (see FIG. 6A) indicating eyelid movement. The blink speed analyzing device 38 for analyzing the blink speed by obtaining the rate of change (differential value) of the electrical signal data measured by the above, and a memory 42 for storing an arithmetic expression indicating the relationship between the blink speed and the arousal level , And the blink speed analyzed by the blink speed analyzing device 38, the arithmetic expression stored in the memory 42,
Is provided with a wakefulness calculator 40 that calculates the wakefulness on the basis of.

Next, the operation of the present embodiment will be described.

As described above, the heartbeat RR interval measuring device 2
6 measures the heartbeat RR interval from the electrical signal (temporal continuous data) from the heartbeat detection electrode 24, and the frequency analyzer 28 determines the first frequency band (0) of the heartbeat RR interval. .15 to 0.5 Hz). Then, the stress degree calculator 30 calculates the stress degree based on the signal strength analyzed by the frequency analysis device 28 and an arithmetic expression indicating the relationship between the signal strength and the stress degree stored in the memory 32.

The electrogram measuring device 36 converts the electric signal from the blink detection electrode 34 into electric signal data representing the movement of the eyelid, and the blink speed analyzer 38 converts the electric signal data of the electric signal data. The blink rate is analyzed by obtaining the rate of change, and the blinking speed calculator 40 analyzes the blinking speed obtained by the blinking speed analyzing device 38 and the blinking speed and the alertness stored in the memory 42. Is calculated based on the following equation:

The fatigue level calculator 16 calculates the stress level measured by the stress level measuring device 12 and the arousal level measured by the arousal level measuring device 14 and the stress level stored in the fatigue level calculating memory 18. The degree of fatigue is calculated based on an arithmetic expression (expression showing each curve in FIG. 7) indicating the relationship between the degree of arousal and the degree of fatigue.

The fatigue level indicator 20 displays the obtained fatigue level to notify the driver, and a warning indicator 22
Displays an instruction to instruct the driver to take a rest according to the degree of fatigue.

Here, an example of the fatigue degree calculation formula shown in FIG. 7 and the measurement of the stress degree, awakening degree and the calculated fatigue degree of the driver who is the evaluation subject shown in FIGS. 8 (A) to 8 (C). The effects of this embodiment will be described with reference to the drawings showing examples.

The time point A is at the beginning of the operation and is shown in FIG.
As shown in FIG. The fatigue level at this time is shown in FIG.
The fatigue level A ″ is calculated from the stress level A ′ using the rightmost graph shown in FIG. Next, at the time point B, the driver is in the middle stage of driving, and the driver is monotonously driven, as shown in FIG. I have. At this time, the fatigue level B ″ is calculated from the stress level B ′ using the leftmost graph shown in FIG. Further, similarly, at the point C,
The degree of fatigue C ″ is calculated from the degree of stress C ′.

The degree of fatigue A ″ calculated as described above,
Comparing B ″ and C ″, especially at point B, although the physiological stress level is low, the calculated degree of fatigue is high, which is equivalent to the evaluation of the actual driver's feeling of fatigue. Shows a tendency to fit well. That is, in the present embodiment, since the calculation can be made to include the feeling of fatigue due to avoidance behavior such as point B, the accuracy of fatigue estimation is higher than estimation based on only the stress level. In the present embodiment, the correlation between the calculated degree of fatigue and the actual degree of fatigue shows a high correlation coefficient (high correlation) of 0.85 as shown in FIG.
In addition, when the degree of fatigue is obtained only from the degree of stress, especially point B
Then, the degree of fatigue becomes B ''', which does not match the actual evaluation of the driver's feeling of fatigue.

Here, Japanese Patent No. 29,123,76 discloses an apparatus for obtaining a degree of stress and a degree of arousal, and for obtaining a mental state of an operator.
The difference is that the degree of fatigue of the operator is obtained from the degree of stress and the degree of arousal. Further, in the device described in Japanese Patent No. 29,123,76, awakening degree in a complete sleep state is obtained by obtaining a sleep brain wave or the like as the degree of awakening. Complete sleep (light sleep)
Is different in that the degree of arousal is determined.

Next, a modification of this embodiment will be described. FIG.
5 shows a fatigue degree calculating device according to a modification of the present embodiment. Since this modification has the same configuration as that of the above-described embodiment, the same portions are denoted by the same reference numerals and description thereof will be omitted. As shown in FIG. 10, the fatigue degree calculation device according to the present modification includes the above-described heartbeat detection electrode 24, heartbeat RR interval measuring device 26, and frequency analysis device 28.
It has.

As shown in FIG. 11, the frequency analyzer 28 according to the present modification obtains two signal intensities at a heartbeat RR interval. That is, the frequency analysis device 28 sets the heart rate R- in the above-described first frequency analysis band (0.15 to 0.5 Hz (the first frequency is 0.3 Hz)).
The signal strength at the R interval and the second frequency analysis band (0.06
０．１0.15 Hz (the second frequency is 0.1)
And the signal strength of The signal strength is an integrated value of the heartbeat RR interval in each frequency band.

The stress level calculator 30 calculates the stress level based on the signal strength of the first frequency analysis band and the calculation formula stored in the memory 32. The arousal level is calculated based on the signal strength of the second frequency analysis band obtained by the device 28 and the calculation formula stored in the memory 42. The rest is the same as the first embodiment described above.

In the present modification, the number of elements (heartbeat detecting electrodes and the like) required for obtaining a physiological quantity can be reduced, and a simple configuration can be achieved.

In the example described above, the electrodes for detecting the heartbeat are arranged on the chest of the driver, but they may be arranged on the arms and ears. Further, a microphone arranged on the chest may be used to detect a heartbeat.

Although the heart rate is used as a physiological quantity relating to stress, the present invention is not limited to this, and stress hormones (adrenaline in urine and cortisol in saliva) may be used. Alternatively, the stress level may be obtained from each of the heartbeat and the stress hormone, and the final stress level may be obtained from the average of the obtained stress levels.

Although the blink speed and the heart rate are used as physiological quantities relating to the degree of arousal, the present invention is not limited to these, and the frequency of blinking, skin potential, skin resistance,
An eye closed state may be used. Alternatively, the degree of awakening may be obtained from each of the blink speed, the heart rate, the frequency of blinking, the skin potential, the skin resistance, and the closed state of the eyes, and the final degree of awakening may be obtained from the average of the obtained degrees of arousal.

In the above-described example, a driver who drives a car is targeted. However, the present invention is not limited to this. Operators who operate other devices (motorcycle drivers, airplane pilots, Plant monitor).

Further, in the above-described example, the arithmetic expression is stored in the memory. However, the present invention is not limited to this. For example, a map or a data table indicating the above relationship may be stored. Is also good.

[0039]

As described above, according to the present invention, the degree of fatigue is calculated using the degree of stress and the degree of arousal. This has the effect that the degree of fatigue can be calculated accurately.

[Brief description of the drawings]

FIG. 1 is a block diagram of a fatigue degree calculating device according to the present embodiment.

FIG. 2 is a block diagram illustrating a configuration of a stress level measuring device.

FIG. 3 is a block diagram showing a configuration of a waking degree measuring instrument.

FIG. 4 is a graph showing an electric signal from a heartbeat detection electrode.

FIG. 5 is a graph showing an arrangement position of blink detection electrodes.

FIG. 6A is an electrogram, and FIG. 6B is a graph showing blink speed.

FIG. 7 is a graph showing the relationship between the degree of stress and the degree of arousal and the degree of fatigue.

FIGS. 8A to 8C are graphs showing measurement examples of the degree of stress, arousal, and fatigue of a driver.

FIG. 9 is a graph showing a relationship between a sensitivity value of a driver's fatigue and a measured value.

FIG. 10 is a block diagram of a fatigue degree calculating device according to a modification of the present embodiment.

FIG. 11 is a graph showing a frequency spectrum of a heartbeat RR interval.

[Explanation of symbols]

 REFERENCE SIGNS LIST 12 Stress meter 14 Arousal meter 16 Fatigue calculator 18 Fatigue calculator memory 24 Heartbeat detection electrode 34 Blink detection electrode

Claims (9)

[Claims] 1. A stress degree calculating means for calculating a stress degree based on a physiological quantity related to stress, an arousal degree calculating means for calculating an arousal degree based on a physiological quantity related to arousal degree, a stress degree and a degree of arousal and fatigue A stress level calculated by the stress level calculation means and a wakefulness level calculated by the wakefulness level calculation means; a stress level stored by the storage means; and a wakefulness level and a fatigue level. And a calculating means for calculating the degree of fatigue based on the relationship. 2. A first detecting means for detecting a physiological quantity related to the stress, and a second detecting means for detecting a physiological quantity related to the arousal level, wherein the stress degree calculating means includes Calculating a stress degree based on a physiological quantity related to the stress detected by the detecting means; the arousal degree calculating means calculating an arousal degree based on a physiological quantity related to the arousal degree detected by the second detecting means; The fatigue calculation device according to claim 1, wherein: 3. The physiological quantity related to the stress includes a second frequency that includes a first frequency and is smaller than the first frequency.
At least one of a heartbeat component and a stress hormone in a first frequency band not including the frequency of the first frequency band, wherein the physiological quantity related to the arousal level does not include the first frequency and includes the second frequency. The fatigue degree calculation device according to claim 1, wherein the heartbeat component is at least one of a heartbeat component, a blinking state, a skin potential, a skin resistance, and an eye open state in the second frequency band. 4. When a component of a heartbeat in the first frequency band is used as a physiological quantity related to the stress, an intensity of a heartbeat in the first frequency band is obtained. 4. The apparatus according to claim 3, wherein when a component of a heartbeat in the second frequency band is used, the intensity of the heartbeat in the second frequency band is obtained. 5. The apparatus according to claim 4, wherein the heartbeat intensity is an integrated value of a heartbeat component in the frequency band. 6. The apparatus according to claim 3, wherein the stress hormone is at least one of adrenaline in urine and cortisol in saliva. 7. A heart rate detecting means for detecting a heart rate, wherein the stress degree calculating means includes a second frequency including a first frequency of the heart rate detected by the heart rate detecting means and smaller than the first frequency. Calculating the stress level based on a component in a first frequency band that does not include the first frequency band, wherein the arousal level calculating means does not include the first frequency of the heartbeat detected by the heartbeat detecting means and the second The fatigue level calculating device according to claim 1, wherein the arousal level is calculated based on a component in a second frequency band including the frequency. 8. The stress level calculation means calculates the stress level based on the intensity of the heartbeat in the first frequency band, and the arousal level calculation means calculates the stress level in the second frequency band. The fatigue level calculating device according to claim 7, wherein the arousal level is calculated based on the strength. 9. The apparatus according to claim 8, wherein the heartbeat intensity is an integrated value of a heartbeat component in the frequency band.