JP2570328B2 - Arousal level determination device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a vehicle driver, a ship or aircraft operator,
The present invention relates to a waking degree determination device suitable for determining a waking degree of a simple worker or the like.

(Prior Art) Conventionally, in this type of arousal level determination device, as shown in JP-A-59-22537, for example, light from a light-emitting diode incident on a finger of a driver of a vehicle is used. When the light reflected by the blood passing through the blood vessel in the finger is received by the phototransistor, the amount of the received light changes in accordance with a change in the amount of the blood synchronized with the heartbeat of the driver (that is, the amount of the blood corresponds to the heartbeat). This pulse wave is also referred to as a heartbeat), and when the average value of the period of the heartbeat and the variation of the same period both increase, the driver falls asleep. In some cases, the dozing state is determined.

(Problems to be Solved by the Invention) However, in such a configuration, since the above-described cycle of the heartbeat also includes a periodic component caused by various disturbances, it is difficult to judge a dozing state without accuracy. There is.

On the other hand, the present inventors conducted the following experiment. When the amplitude Am of each heartbeat (or a pulse wave corresponding to the heartbeat) appearing for each heartbeat in an electrocardiogram of a subject is measured with time, each heartbeat is observed when the subject is in a nervous state (excited state). The amplitude Am of the heartbeat is obtained as the data shown in FIG. 2. When the subject is in a normal state (conversation state), the amplitude Am of each heartbeat is obtained as the data shown in FIG. ) When the amplitude of each heartbeat
Am was obtained as the data shown in FIG. Thus, as will be easily understood by comparing the data shown in FIGS. 2 to 4, the amplitude Am of each heartbeat becomes extremely large in the sleep state shown in FIG.

Therefore, the present inventors intend to provide a wakefulness determination device that can easily and accurately determine a decrease in the wakefulness of a person based on such experimental results.

(Means for Solving the Problems) In order to solve the above problems, as shown in FIG. 1, the present invention provides a detecting means (1) for sequentially detecting the intensity of a human heartbeat as an amplitude, Sometimes the amplitude detected by the detection means,
Setting means (2) for setting as a reference amplitude corresponding to the intensity of the heartbeat at the time of awakening of the human; and sequentially comparing each amplitude detected by the detecting means with the reference amplitude after the setting means sets the reference amplitude. do it,
A determination unit configured to determine whether the decrease in the arousal level of the human is within an allowable limit.

(Function and Effect) According to the present invention configured as described above, the amplitude detected by the detection unit when the human is awake is set by the setting unit as the reference amplitude corresponding to the intensity of the heartbeat when the human is awake. Then, after such setting, the determination unit sequentially compares each amplitude detected by the detection unit with the reference amplitude to determine whether the decrease in the degree of arousal of the person is within an allowable limit.

As described above, based on the phenomenon that the amplitude corresponding to the intensity of the human heartbeat greatly differs before and after falling asleep, the reference amplitude set by the setting unit when the human is awake and the intensity of the human heartbeat after this setting are set. By sequentially comparing the detected amplitudes with the respective detected amplitudes, it is determined whether or not the decrease in the arousal level of the person is within the allowable limit. Therefore, it is possible to easily and accurately recognize the degree of decrease in the arousal level of the person.

In this case, the setting of the reference amplitude by the setting means is performed based on the amplitude detected by the detecting means when the human is awake, as described above. Therefore, when the person whose arousal level is to be determined is changed to a new person, the setting of the reference amplitude by the setting means is newly performed based on the amplitude detected by the detecting means when the new person is awake.

Then, a comparison between the new set reference amplitude and each of the detected amplitudes detected by the detecting means with respect to the intensity of the new human heartbeat indicates whether the reduction in the new human arousal level is within the allowable limit. Is determined. Therefore, even if the person who should determine the arousal level changes, the accuracy of the determination does not decrease.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 5 shows an example of an awakening degree determination device according to the present invention applied to a vehicle. The arousal level determination device includes a photocoupler 20 attached to the right grip 11 of the steering handle 10 of the vehicle, and a light emission drive circuit 30 connected to the photocoupler 20.
And a preamplifier 40.
As shown, the right grip of the steering handle 10
An insulating substrate 21 mounted in the recess on the inner peripheral surface of 11 and this insulating substrate
It comprises a light emitting diode 22 and a phototransistor 23 fitted in parallel at an interval to each other. However, the light emitting surface of the light emitting diode 22 and the light emitting surface of the phototransistor 23 are both exposed outward from the surface of the insulating substrate 21.

Thus, in the photocoupler 20 configured as described above, the thumb of the driver's right hand covers the light emitting surface of the light emitting diode 22 and the light receiving surface of the phototransistor 23, as shown in FIG. When the light comes into contact with the photo transistor 23, light generated from the light emitting diode 22 is reflected by blood passing through the blood vessel in the thumb and enters the phototransistor 23. The phototransistor 23 generates a light receiving signal at a level corresponding to the amount of incident light. In such a case, the phototransistor 23
The amount of light incident on the driver changes in accordance with the above-described change in the amount of blood synchronized with the driver's heartbeat R.

The light emitting drive circuit 30 drives the light emitting diode 22 so as to continuously generate a predetermined amount of light composed of the light emitting diode 22. The preamplifier 40 amplifies a light receiving signal from the phototransistor 23 and generates an amplified signal. Filter 50 is
The noise component in the frequency component of the amplified signal from the preamplifier 40 is removed, and the remaining component is generated as a filter signal.
The main amplifier 60 amplifies the filter signal from the filter 50 and generates an amplified signal. The AD converter 60a is a main amplifier 60.
The digitally converted amplified signal is generated as a digital amplified signal. The microcomputer 70 executes the computer program in cooperation with the A / D converter 60a in accordance with the flowchart shown in FIG. Perform processing.

In the present embodiment configured as described above, when the driver grips the steering wheel 10 with both hands to start driving and running the vehicle when the driver is awake, and when the device of the present invention is in the operating state, the light emission driving circuit 30 A predetermined amount of light generated from the light emitting diode 22 under driving enters the right thumb of the driver (see FIG. 6) and is reflected by blood passing through blood vessels in the thumb, and the reflected light is phototransistor. Received by 23. At this time, the amount of light received by the phototransistor 23 changes according to a change in the amount of blood synchronized with each heartbeat R of the driver. That is, it appears as a pulse wave corresponding to a heartbeat.

Therefore, a light receiving signal is generated from the phototransistor 23 at a level that changes according to the light receiving amount that changes in this manner,
The signal is amplified by the preamplifier 40 as an amplified signal. Next, when the filter 50 generates a filter signal in response to the amplified signal from the preamplifier 40, the filtered signal is generated as an amplified signal by the main amplifier 60, and the amplified signal is digitally amplified by the A / D converter 60a. The signal is generated and provided to the microcomputer 70. The microcomputer 70 starts the execution of the computer program in step 100 according to the flowchart of FIG.
At 0, initialization is performed. Further, with this initialization, the microcomputer 70 sets the timer data D to zero and sets the initial amplitude Ao to zero. However, the initial amplitude Ao represents the initial amplitude of the driver's heartbeat.

Then, the microcomputer 70 executes step 120
At, the value of the digital amplified signal from the A / D converter 60a is input as the digital amplitude Amd, and at step 130, it is determined as “YES” based on the timer data D = 0 at step 110 <the predetermined time Do, In step 140, it is determined as "YES" based on the digital amplitude Amd in step 120> the initial amplitude Ao in step 110, and in step 150, the digital amplitude Amd in step 120 is set to the initial amplitude.
Ao is set, and at step 160, “1” (corresponding to 1 msec) is added to the timer data D (= 0), and the addition result is updated as D. However, the predetermined time Do corresponds to the time required to specify the maximum value of the amplitude Am of the heartbeat (see FIG. 2) in the driver's normal state, and is stored in the ROM of the microcomputer 70 in advance.

Thereafter, in the process of repeating the execution of the computer program passing through each of steps 120 to 160, the digital amplitude Amd in step 120> the initial amplitude Ao in step 150
In step 150, the digital amplitude Amd is set to Ao in step 150.
On the other hand, when Amd ≦ Ao, the update of Ao is prohibited. In this state, if the determination in step 130 becomes “NO” in relation to the latest timer data D in step 160, the microcomputer 70 advances the computer program to step 170. This means that the maximum value of the heartbeat amplitude in the driver's normal state is Ao
Means that it could be set as

Thereafter, since the driver is in a normal state, the microcomputer 70 determines in step 170 that the latest digital amplitude Amd in step 120 ≦ the latest initial amplitude Ao in step 150, and determines `` NO ''. At 190, the timer data D is added and updated, and the computer program proceeds to step 120. Thereafter, during the repetition of the same calculation, if the determination in step 170 is “YES”, the microcomputer 70 generates an alarm output signal in step 180 based on the determination that the driver is just before falling asleep. In response, the buzzer drive circuit 80
Sound. As a result, the driver is alerted to the fact that the driver is in the dozing driving state. In other words, by utilizing the difference between the normal state and the sleep state of the amplitude of the driver's heartbeat, the latest initial amplitude Ao in step 150 when the determination in step 130 is NO in the normal state of the driver. By sequentially comparing the digital amplitude Amd in step 120 after the determination of NO in step 130 with the digital amplitude Amd, it is determined whether or not the driver is just before falling asleep. Therefore, an alarm for preventing the driver from falling asleep can be easily and correctly issued.

In this case, Ao of the maximum value of the amplitude of the heartbeat at the time of determination of NO in step 130 (see step 150) corresponds to the pulse wave corresponding to the heartbeat of the new occupant if the driver changes to a new occupant. A new level is set based on the light receiving signal from the phototransistor 23 at the set level.

This means that when the driver whose arousal level is to be determined is changed to a new occupant, the maximum value of the amplitude of the heartbeat of the new occupant in the calm state is newly set as Ao. Therefore, even if the person whose arousal level is to be determined changes, an alarm for preventing the person from falling asleep can be easily and correctly issued.

In practicing the present invention, instead of the photocoupler 20, an insulating member 12 is fixed to the center of the surface of the steering handle 10, as shown in FIG. When the driver holds the steering handle 10 with both hands, the heart rate R of the driver is fixed when the metal electrode 14 is fixed to the surface of the steering handle 10 on the right side of the insulating member 12.
The fluctuation of the potential difference generated between both hands in synchronization with
The same operation and effect as those of the above-described embodiment can be achieved even if the detection result is detected from 3, 14 and the detection result is amplified as an amplified signal by the preamplifier 40A and applied to the filter 50.

Further, in practicing the present invention, the alarm means is not limited to the buzzer 90, and may be implemented by using a display means, a voice synthesizing means and other various notification means.

In the above-described embodiment, the example in which the present invention is applied to the determination of the arousal level of the driver of the vehicle has been described.
The present invention is not limited to this, and the present invention may be applied to the determination of the alertness of a ship or aircraft operator, a simple worker in a factory, a patient, and the like.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to the configuration of the invention described in the claims, FIG. 2, FIG. 3, and FIG.
FIG. 5 is a block diagram showing an embodiment of the present invention, and FIG. 6 is a cross-sectional view of the photocoupler shown in FIG. 5, and FIG. FIG. 5 is a flowchart showing the operation of the microcomputer shown in FIG. 5, and FIG. 8 is a block diagram showing a main part of a modification of the embodiment. DESCRIPTION OF SYMBOLS 12 ... insulating member, 13,14 ... metal electrode, 20 ... photocoupler, 30 ... light emission drive circuit, 70 ... microcomputer.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Satoru Kodama 1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (56) References JP-A-62-26046 (JP, A)

Claims (1)

(57) [Claims] 1. A detecting means for sequentially detecting the intensity of a human heartbeat as an amplitude, and an amplitude detected by the detecting means when the human is awake is set as a reference amplitude corresponding to the intensity of the heartbeat when the human is awake. Setting means for setting the reference amplitude, the setting means sets the reference amplitude, and sequentially compares each amplitude detected by the detecting means with the reference amplitude to determine whether the decrease in the arousal level of the human is within an allowable limit. An arousal level determination device including a determination unit.