JP3271430B2 - Dozing warning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drowsiness warning device,
In particular, the present invention relates to a drowsiness warning device that can be used for preventing a drowsy driving in a vehicle.

[0002]

2. Description of the Related Art In recent years, with the increasing number of traffic accidents, each driver has been increasingly required to drive safely. Various measures have been taken.

For example, in Japanese Utility Model Laid-Open No. 5-39506, the heart rate of a driver is detected by a heart rate sensor provided on an arm band, and when the heart rate falls below a specified value, the driver's awakening degree is reduced. There is disclosed a technique of judging that it is decreasing and giving a warning to a driver to call attention.

[0004] In general, when drowsiness occurs during driving, the driver consciously or unconsciously tries to wipe out drowsiness, such as elongating or stretching his back or sitting down again (an action that accompanies such drowsiness). Are called secondary actions).

[0005] Normally, the heart rate decreases when the user falls asleep, but in the case of a driver with many secondary actions, a temporary increase in the heart rate often mixes, and as a result, as shown in FIG. The average value of the heart rate ((a) in the figure) and the average value of the heart rate during the drowsy driving ((b) in the figure) hardly change.

Accordingly, such a driver's falling asleep cannot be detected merely by lowering the heart rate as in the above-described prior art.

The applicant of the present invention has disclosed in Japanese Patent Application No. 6-22736 a device aimed at accurately detecting dozing without using an average value of heart rate and generating a warning. The contents are as follows.

<Contents of Japanese Patent Application No. Hei 6-22736> The raw heartbeat signal has a waveform as shown in the electrocardiogram of FIG. 6, and the highest mountain of the electrocardiogram is called an R wave. The interval from the R wave is called an RRI (RR interval). This RRI
The value corresponds to the heartbeat interval (or heart rate) in FIG.

The length of the RRI is read from the heartbeat interval between the R waves provided as an output signal of the heartbeat sensor, and plotted for each beat to obtain a heartbeat fluctuation waveform as shown in FIG.

[0010] This heartbeat fluctuation waveform indicates that the heart does not always beat at regular intervals, but constantly fluctuates and fluctuates.

In the graph of FIG. 7, since the length of the RRI is set on the vertical axis, the value of the RRI decreases as the heart rate increases,
This indicates that a slower heart rate results in a higher RRI.
Also, when the driver becomes drowsy and the heart rate slows down, the RRI rises and the average value X ₀ at the time of awakening determined in advance.
Values are often higher than

In such a heart rate variability waveform, the average value in the illustrated section is almost the same as the average value X ₀ at the time of awakening, but the integral value indicating a state in which dozing gradually progresses. Since the value of the portion painted black is larger than the value at the time of awakening, the value appears to be dozing.

In the section, this average value is clearly less than the average value X ₀ and no drowsiness can be detected. However, the area (integral value) of the black portion is determined, and this value is used as a reference. If it is checked whether the value is equal to or more than the value, the dozing detection can be performed.

Therefore, when the drowsy alarm device is worn (ie, when awake), all RRI values of a predetermined number of heartbeats detected by the heartbeat sensor are obtained, the average value thereof is obtained, and the RRI value exceeding the average value is obtained. The integral value is multiplied by a predetermined value and determined as a threshold value.

As described above, the average value of the RRI values and the threshold value are determined at the time of awakening, and thereafter, for example, when the vehicle is driven, a predetermined number of RRI values similar to the above are determined.
Among these RRI values, RRI values exceeding the above-determined average value are integrated. That is, the area of the portion painted black in FIG. 7 is obtained.

When the integrated value exceeds the above-mentioned threshold value, a warning can be given to a driver or the like by driving a warning generating means from the control unit.

[0017]

However, in the above-mentioned Japanese Patent Application No. 6-22736, during calculation of the average value X ₀ at the time of awakening, the driver moves his body, sighs, or When an action such as conversation is taken, the RRI value is rapidly reduced, so that an accurate average value X ₀ cannot be obtained, and there has been a problem that accurate dozing detection cannot be performed.

That is, as shown in the graph of the heart rate versus the RRI value shown in FIG.
Since the I value fluctuates greatly (in this case, the variance value σ ² is large), an accurate average value X ₀ during awakening cannot be obtained.
On the other hand, in the section, the fluctuation of the RRI value is small (the variance value is small), and the average value X _{0 at} this time is reliable.

Accordingly, the present invention provides an RRI of a heartbeat at waking.
It is an object of the present invention to provide a device that accurately detects a dozing state without issuing an average value that is always correct and generates a warning.

[0020]

In order to achieve the above object, a dozing warning apparatus according to the present invention comprises a heart rate sensor,
A warning generating means, a threshold value of an average value of all RRI values of a predetermined number of heartbeats detected by the sensor at the time of awakening and a predetermined multiple of an integral value of an RRI value exceeding the average value as a threshold value; A control unit that integrates an RRI value exceeding the average value among the RRI values and activates the warning generating means when the threshold value is exceeded, and the control unit reduces the average value. In the calculation, the variance of the RRI value is also obtained, and when the variance exceeds a predetermined value, the average value and the variance are recalculated.

[0021]

According to the present invention, first, when the dozing warning device is worn (ie, when awake), as in Japanese Patent Application No. 6-22736.
The total R of a predetermined number of heartbeats detected by the heartbeat sensor
The RI value is calculated and its average value X ₀ is calculated. At the same time, the variance σ ^{2 of the} RRI value is also calculated.

If the variance value σ ² exceeds a predetermined value, the driver takes actions such as moving his body, sighing or talking as described above, and as a result, Assuming that X ₀ is a fluctuating and unreliable value (see FIG. 8), the average value X ₀ and the variance σ ² are calculated again without using the average value X ₀ at this time.

If the variance value σ ² does not exceed the predetermined value, the recalculated average value X ₀ is a reliable value.
Further, an upper limit value obtained by multiplying the average value X ₀ by a predetermined value and the average value X ₀
Is multiplied by a predetermined value and the threshold value is determined and stored.

Thereafter, a predetermined number of RRI values are obtained in the same manner as described above, for example, when the vehicle is running, and among these RRI values, the RRI values exceeding the above average value X ₀ are integrated.

Then, by integrating the RRI value exceeding the average value obtained above, the area of the black-out portion in FIG. 7 is obtained.

When the integrated value exceeds the above threshold value, a warning of drowsy driving can be given to a driver or the like by activating the warning generating means from the control unit.

In this manner, since the integration using only the reliable average value X ₀ in the RRI value is performed, an accurate drowsy alarm can be issued.

[0028]

FIG. 1 shows an electric circuit configuration of a drowsiness warning apparatus according to the present invention.
In the figure, 1 is a control unit, 2 is a heart rate sensor, 3 is a warning piece that gives a slight electric shock as a warning generation means, and 4 is a control unit 1 and a heart rate sensor 2. A power supply section for supplying power, 5 is a switch for activating the power supply section 4, 6 is an arithmetic circuit that performs an operation by receiving an output signal of the heart rate sensor 2, and 7 is driven by an output signal of the arithmetic circuit 6. This is a transmission circuit for driving the warning piece 3.

FIGS. 2 and 3 show a state in which the doze warning apparatus according to the present invention shown in FIG. 22736
The control unit 1 is provided on the surface of the arm band 10, but the heart rate sensor 2 and the warning piece 3 are attached to the back side of the arm band 10. As shown in (a) and (b), when the wrist is firmly wound by the hook-and-loop fasteners 10a provided on both sides of the arm band 10, the heart rate sensor 2 and the warning strip 3 come into direct contact with the wrist, and the control unit 1 The switch 5 can be operated from the outside of the arm band 10.

FIG. 4 shows a flowchart of a program stored and executed in the arithmetic circuit 6 in the control unit 1 shown in FIGS.
1 to 3 with reference to the flowchart of FIG.
The operation of the embodiment shown in FIG.

First, when the wristband 10 is used to prevent drowsy driving, the driver turns on the power supply unit 4 by operating the switch 5 in the control unit 1 and starts the flowchart shown in FIG. When the switch 5 is pressed, for example, the power supply unit 4 continues to operate. When the switch 5 is pressed again, the switch 5 is restored to its original state and the operation of the power supply unit 4 can be canceled.

As described above, when the power is turned on, that is, at the time of awakening as an initial state, the heart rate sensor 2 outputs a heartbeat raw signal as shown in FIG.

The arithmetic circuit 6 fetches a predetermined number of RRIs, for example, 60 beats, and stores them in a built-in memory (not shown) (step S1).

The RRI average value X for the 60 beats
₀ and a variance value σ ² are obtained (step S2).

This variance value σ ² is equal to a predetermined upper limit value A (for example,
5000 msec ² ) is determined (step S)
3). This is to judge whether the average value X ₀ calculated at the same time is reliable or not. Only when σ ² ≦ A, the average value X ₀ is regarded as accurate and the process proceeds to the next step S4. move on.

In step S4, the integrated value Y ₀ of the RRI exceeding the average value X ₀ obtained in this manner is further obtained, and a threshold value K · Y ₀ obtained by multiplying the integrated value Y ₀ by a predetermined coefficient is obtained. .

The above constant K is, for example, “3”, which is a value that indicates how long it can be determined to fall asleep from the time of awakening. No problem.

In this way, the RRI during the initial awakening
The average value X ₀ and the threshold value K · Y ₀ are obtained in advance, and the drowsiness driving at the time of subsequent traveling or the like is determined.

That is, first, in the same manner as above, R for 60 beats
The RI value is fetched and stored in the memory (step S
5).

Then, of the fetched RRI values, those exceeding the average value X ₀ obtained in step S2 are extracted, and the integrated value Y is obtained (step S6).

As a result, a magnitude relationship between the integral value Y at the time of running or the like and the threshold value K · Y ₀ at the time of initial awakening is determined (step S7).

That is, when it is determined that the integrated value Y during running or the like is equal to or less than the threshold value K · Y ₀ at the time of awakening, step S5
When it is determined that the integrated value Y is larger than the threshold value K · Y ₀ , it is determined that the vehicle is in the dozing operation state, and the arithmetic circuit 6 drives the transmission circuit 7 (step S8).

Therefore, the transmission circuit 7 can give a warning signal to the warning piece 3, and the warning piece 3 can give a slight electric shock to the driver. The warning can be given not only by such an electric shock but also by sound or vibration.

After such a warning is given for a predetermined time (step S9), the process returns to step S5 to repeat the above operation.

In the above embodiment, the alarm piece 3 is attached to the wristband 10, but it may be provided on an external dashboard, for example, to receive all signals by radio waves. Good.

[0046]

As described above, according to the dozing warning apparatus of the present invention, the average value and the variance value of the RRI value of a predetermined number of heartbeats at the time of awakening and the average value when the variance value is equal to or less than the predetermined value. , A threshold value that is a predetermined multiple of the integrated value of the RRI value that exceeds the threshold value is calculated, and then the RRI value that exceeds the average value among the RRI values that are calculated in the same manner is calculated and calculated. When the driver is asleep, a warning is generated assuming that dozing has occurred. Therefore, the RRI value during the drowsy driving or the like suddenly decreases due to the driver's body movement or the like (see FIG. 8), or the vehicle moves suddenly. Even if noise is mixed in the heartbeat signal due to, for example, erroneous detection of the R wave and abnormally large or small RRI value, the average value of that part can be canceled and only the accurate average value can be used, Exactly dozing It is possible to detect the rotation. Also,
Since the calibration for obtaining the average value of the individual at the time of awakening is performed, accurate dozing detection corresponding to the individual difference can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electric circuit configuration of a dozing warning device according to the present invention and Japanese Patent Application No. 6-22736.

FIG. 2 is an external view when a doze warning device according to the present invention and Japanese Patent Application No. 6-22736 is provided on an arm band.

FIG. 3 is a view showing a drowsiness warning device according to the present invention and Japanese Patent Application No. 6-22736 when the device is provided with an arm band and attached to a wrist.

FIG. 4 is a flowchart of a program stored and executed in a control unit used in the drowsiness warning device according to the present invention.

FIG. 5 is a waveform diagram showing a time change of a heart rate at the time of awakening and at the time of drowsy driving, respectively.

FIG. 6 is an electrocardiogram waveform diagram showing a raw heartbeat signal obtained by a heartbeat sensor.

FIG. 7 is a diagram showing a heartbeat fluctuation waveform of RRI obtained by a heartbeat sensor.

FIG. 8 is a waveform chart showing a relationship between an average value and a variance value of RRI values.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control unit 2 Heart rate sensor 3 Warning piece 4 Power supply unit 5 Power switch 6 Arithmetic circuit 7 Oscillation circuit 10 Arm band

Continuation of the front page (56) References JP-A-7-228171 (JP, A) JP-A-2-6231 (JP, A) JP-A-57-66735 (JP, A) JP-A-61-106130 (JP) , A) Hira 5-39506 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 5/00-5/03

Claims (1)

(57) [Claims] 1. A heart rate sensor, a warning generating means, and an average value of all the RRI values of a predetermined number of heartbeats detected by the sensor when the sensor is awake, and an RRI exceeding the average value.
A predetermined multiple of the integrated value of the values is calculated as a threshold value, and among the predetermined number of RRI values, an RRI value exceeding the average value is integrated, and the warning generating means is added when the RRI value exceeds the threshold value. A drowsiness warning device comprising a control unit that activates the RRI value, the control unit also calculates a variance value of the RRI value when calculating the average value, and calculates the average value when the variance value exceeds a predetermined value. And a re-calculation of the variance value.