JPH0669444B2 - Vehicle occupant condition detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle occupant state detection apparatus suitable for detecting the physical state of a vehicle occupant, particularly a vehicle driver.

«Conventional technology» Conventionally, as a means for grasping the physical condition of the driver for safe driving of a vehicle, an abnormal steering operation pattern due to a drowsiness driving state or the like is stored and an actual steering angle change is stored. In comparison with the above pattern, there is proposed a driver's abnormal state detection device which issues an alarm by discriminating an abnormal state such as drowsiness when they match or are similar.

Further, a grip pressure detecting element is provided on the steering wheel of the driver, and when the grip pressure decreases for a predetermined time,
A device that gives an alarm to the driver has also been proposed.

There is also proposed a device in which a fingertip pressure detector for detecting a heartbeat state is attached to the driver's thumb or the like so that the driver can grasp the state of the driver's body from the heartbeat state and issue a warning. (JP-A-60-76428).

<< Problems to be Solved by the Invention >> By the way, in the case of directly measuring the state of the body as in the above-mentioned prior art, the inconvenience that the detection element has to be directly attached to the body and the detection element on the body Due to the emotional pressure or discomfort of mounting, there was the inconvenience that an accurate respiratory rate or heart rate could not be measured.

Further, in the method of detecting the steering operation state and grasping the state of the driver, the pattern of the steer ring operation by dozing is complicated and various, and does not always match the pattern preset in the storage means. However, there is a problem that the detection accuracy is not so good.

In addition, when detecting the gripping pressure of the steering wheel, when grasping the driver's state, especially during high-speed driving on a straight line or in congested driving, the gripping pressure of the steering naturally changes, so the driver's accurate state should be maintained. There is a drawback in that it is impossible to grasp the driver's condition because the steering wheel cannot be grasped differently depending on the person.

Further, in the device equipped with the fingertip pressure detector, there is a problem that the driver feels uncomfortable, and therefore, if the driver removes the detector, it cannot be detected at all.

«Object of the Invention» The present invention has been made to solve the above problems, and an object of the present invention is to indirectly detect the state of the body without directly contacting the sensor with the body. (EN) Provided is a vehicle occupant state detection device.

<< Means for Solving the Problems >> In order to solve the above problems, the present invention provides a microwave transmission / reception sensor for receiving a reflected wave of a microwave applied to the chest or abdomen of a vehicle occupant, and the microwave transmission / reception sensor. Displacement amount calculation means for calculating a signal representing the displacement state of the chest or abdomen from the detection signal received by the transmission / reception sensor, and the period, amplitude or the calculated symbol in the predetermined period of the signal calculated by the displacement amount calculation means. Displacement state detecting means for detecting at least one of the maximum value and the minimum value, and respiratory state comparing means for comparing a value based on the value detected by the displacement state detecting means with a predetermined value. It is characterized by.

<< Operation >> With the above-described configuration, the present invention receives the reflected wave of the microwave emitted toward the chest of the vehicle occupant, particularly the driver, detects the signal indicating the displacement state of the chest, and detects the period of this signal or The physical condition is detected based on the respiratory condition detected from the peak value.

<< Example >> An example of detecting an abnormal state of the body of a vehicle driver will be described below as an example according to the present invention with reference to the drawings.

Before the description based on the drawings, in order to facilitate understanding of the present invention, the relationship between the body condition and the breathing condition of the driver, and the steering angle of the steer rig will be described.

First, when the driver changes lanes or makes a right or left turn while driving in an urban area, etc., the driver is in a nervous state and will not fall asleep. If not, when the driver falls asleep, the steering angle is smaller than a predetermined value, and since the brain cells rest during the breathing cycle, the amount of oxygen required is reduced and becomes slower than in the normal state. So-called breathing fluctuations tend to be slower, and the maximum inspiratory value (positive peak value) and the maximum inspiratory value (negative peak value) of the processed displacement signal described below based on the amplitude of respiration are The positive peak value decreases, but the negative peak value tends to increase.

Also, when the driver is in a fatigued state, the autonomy increases and the breathing cycle tends to become regular, and the amplitude of breathing tends to become shallow. Get smaller.

Furthermore, when the driver is in an extremely tense state or abnormal cardiac system, the amplitude of breathing becomes smaller (the breathing becomes shallower), and the breathing cycle becomes faster or slower. Is turbulent, and its tendency is not constant but turbulent.

Therefore, if the above tendency can be accurately detected, the physical condition of the driver can be accurately grasped, and if the abnormal condition is known, appropriate measures can be taken for the driver or the passenger.

Now, FIG. 1 is a block diagram showing the configuration of the first embodiment of the present invention, in which 1 is a vehicle driving seat, on which a driver 2 is seated.

3 is a microwave Doppler radar sensor (hereinafter referred to as "sensor") as a microwave transmission / reception sensor,
The microwave of the 10 GHz band is emitted to the chest of the driver 2 and the reflected wave can be received.

Reference numeral 4 denotes a detection signal calculation means for calculating the signal received by the sensor 3, and calculates a displacement amount according to the displacement of the epidermis surface of the chest due to the movement of the breath and blood vessels. That is, the amount of change in the distance between the sensor and the body due to the contraction and expansion of the blood vessel caused by the microwaves emitted from the sensor 3 due to respiration or movement of the heart is calculated.

Reference numeral 5 in the figure is a zero cross detector, which detects a point where the reflected wave intersects the reference line, and compares the intersection position with the reference frequency from the reference frequency oscillator 7, that is, the reference frequency is present between the intersection positions. Zero depending on how many times it oscillates
The breathing cycle is detected by the cross cycle counter 6.

8 and 9 are means for detecting the amplitude of respiration,
It is composed of a positive peak hold circuit and a negative peak hold circuit, and holds respective maximum value signals for a predetermined time, and these signals are transferred to a microcomputer () via an analog-digital (A / D) converter. CP
U) sent to 11.

Reference numeral 15 in the figure denotes a steering wheel, which is detected by the steering angle sensor 12, and the detection signal is sent to a steering comparison circuit 13 for comparing a steering angle during traveling and a predetermined value, When the steering angle is less than the specified value, the output signal is CP
Input to U11.

The CPU 11 is driven by a built-in system ROM, and when the driver is normal, that is, in a relaxed state immediately after the engine is started (here, the steering angle is below a predetermined value), positive breathing, The negative peak value and the cycle are stored in advance in the RAM, and the respiratory cycle input from the zero-cross cycle counter 6 and the input from the A / D converter 10 when the steering angle during driving is less than a predetermined value. It is designed to compare and calculate with positive and negative peak values.

Reference numeral 14 in the drawing is an alarm circuit for issuing a warning when the CPU 11 detects an abnormal condition of the driver based on the result of the comparison calculation.

FIG. 2 shows a detailed block diagram of the detection signal calculation means 4. That is, the detection signal calculation means 4 adopts the two-phase displacement detection method, and includes 20a and 20b.
Is a microwave oscillator 21a that generates two types of microwaves in the 10 GHz band having a π / 2 phase difference and a horn antenna 2
1b is a detector provided on the waveguide with a predetermined distance. The signals detected by the wave detectors 20a and 20b are input to the first and second absolute value circuits 24 and 25 after removing the direct current component due to the reflected wave of the stationary object in the background of the body by the high-pass filters 22 and 23, respectively. 3 phase oscillator circuit 2
It is input to the first multiplication circuit 27 which operates at the reference oscillation frequency of 6 sin ωt and the second multiplication circuit 28 which operates at the reference oscillation frequency of cos ωt of the three-phase oscillation circuit 26.

The output signals of the high-pass filters 22 and 23 are multiplied by the third multiplication circuit 29 and then si from the three-phase oscillation circuit 26.
After passing through the oscillation signal switch 30 that switches the reference oscillation frequency of nωt and −sinωt, the output signal of the first absolute value circuit 24 is multiplied by the third multiplication circuit 31.

Furthermore, the output signal of the second absolute value circuit 25 is a three-layer oscillator circuit.
After passing through the fourth multiplication circuit 32 which operates at the reference oscillation frequency of 26 cosωt, the output signal of the third multiplication circuit 31 is added by the first addition circuit 33.

On the other hand, the output signals of the first multiplication circuit 27 and the second multiplication circuit 28 are added by the second addition circuit 34 and then sent to the sample and hold circuit 35.

Here, the absolute value circuits 24, 25 and the multiplication circuits 27, 28, 29, 3
1,32, three-phase oscillation circuit 26, oscillation signal switching circuit 30,
The approximate expression calculation for obtaining the distance from the sensor 3 to the chest determined by a function such as a sine wave is divided into two systems. Further, the adder circuits 33 and 34 combine two signals having different phases.

The output signal of the first adding circuit 33 is processed by the waveform shaping circuit 36, the phased locked loop circuit 37 and the delay circuit 38 so as to be synchronized with the output signal of the second adding circuit 34, It is sent to the sample and hold circuit 35.

The sample and hold circuit 35 takes out the synchronously detected waveform and sends it to a means for detecting a respiratory cycle and a respiratory depth which will be described later.

FIG. 3 shows a detection state in the detection calculation means 4, FIG. 3A shows a waveform obtained by processing a signal received by the detector 20a, and FIG. A signal obtained by receiving and processing a signal having a π / 2 phase difference by the detector 20b is shown.

By combining the above waveforms (a) and (b), the waveform on the left side of FIG. That is, according to the two-phase displacement method, the displacement amount can be detected without generating a low-sensitivity region near the reference position which is caused by the sensitivity characteristic of the detector when the microwave of only one phase is irradiated. The displacement amount of the movement of the blood vessel associated with the beating of the heart, which is shown as a whisker and appears on the waveform of FIG. 7C, can also be detected accurately. The right part of FIG. 7C shows the waveform when breathing is intentionally stopped, and even at this time, the movement of blood vessels, that is, the heartbeat state can be clearly detected. .

In the present embodiment having the above-described configuration, when the sensor 3 irradiates the driver 2 with a microwave of 10 GHz band, the microwave penetrates the driver's clothing, reaches the chest surface, is reflected, and the sensor again. 3 is received.

The received wave is processed by the detection calculation circuit 4, and a waveform signal corresponding to the amount of displacement of the chest is obtained.

In the zero cross detector 5, the waveform signal from the detection calculation circuit 4 is determined to have an intersection with a reference position which is set approximately in the middle between the positive and negative peaks in the normal state, and the zero cross is performed between the intersection positions. The breathing cycle is detected by the cycle counter 6. The detection signal from the detection signal calculation circuit 4 is detected by the positive peak hold circuit 8 and the negative poke hold circuit 9, and the CPU 11 via the A / D converter 10 is detected.
The positive peak value and the negative peak value are detected.

The CPU 11 previously stores a breathing cycle and a positive peak value in a relaxed state immediately after the engine starts, for example, when the driver is normal,
Since the data of the negative peak value is stored, the respiratory cycle input from the zero cross cycle counter 5 and the A / D converter 10 and the positive and negative peak values are compared and judged. When the value becomes larger than that in the normal state, or the positive peak value becomes smaller and the negative peak value tends to become larger than that in the normal state, it is determined that the driver is in a dozing state, and the alarm circuit 14 notifies the driver or Make sure to alert passengers.

First, when the breathing cycle becomes faster or the positive and negative peak values become smaller, it is determined that the driver is in a fatigued state, and the warning circuit 14 issues a warning.

If the positive / negative peak value becomes smaller (the breathing becomes shallower) or the breathing cycle becomes faster or slower and the breathing cycle is disturbed, and the tendency is not constant, the driver It is judged that there is an extremely tense state or an abnormal state of the heart system, and the alarm circuit issues an alarm. It should be noted that if there is a tendency for such a state to return to a normal level within a few seconds, there is no problem, so no alarm is issued.

Therefore, according to the present embodiment, the breathing state of the driver's body is indirectly detected by the breathing cycle or the positive and negative peak values without directly contacting the device, and the state is compared with the normal state to determine whether the state is abnormal. If it is abnormal, a warning to that effect is given.

FIG. 4 shows a second embodiment of the present invention, which differs from the first embodiment described above in that the output of the detection arithmetic circuit 4 is passed through the low-pass filter 16 and then the first By performing the process shown in the embodiment, the period of displacement and positive / negative peak values due to only breathing are detected, and the output signal of the detection arithmetic circuit 14 described above via the high-pass filter 17 is zero cross The detector 5'detects an intersection with the reference position, and this intersection is compared with the reference frequency input from the reference frequency oscillator 7'to detect the cycle of the heartbeat displacement amount by the zero-cross cycle counter 6 '.

In the detection of the cycle of the heartbeat displacement amount, a large wave is removed by the high-pass filter from the output waveform of the detection calculation circuit 4, and only a rapid wave, that is, a high frequency wave is detected.
That is, a large change in the chest due to respiration is removed, and the heartbeat due to the movement of the heart, which is the movement of blood vessels, can be detected. That is, only the whisker-like signal in FIG. 3C can be extracted.

That is, in an extremely tense state or when the heart system is abnormal, the breathing cycle becomes faster, so the heartbeat cycle becomes faster and the heart rate also increases. Then, by comparing with the heart rate within a predetermined time during normal operation, it is possible to determine whether or not an abnormal condition has occurred and issue an alarm.

Therefore, in the second embodiment, since the heartbeat state is further detected in addition to the configuration of the first embodiment, the CPU previously stores the breathing cycle, the positive / negative peak value, and the heart rate of the driver during normal operation. By storing the cycle, it is possible to compare and judge the breathing state and the heartbeat state of the driver to determine whether or not there is an abnormality. Therefore, it is possible to detect the physical state of the driver with higher safety. Especially in the case of extreme tension or abnormal heart system,
Double safety measures can be taken by diagnosis based on the cycle and amplitude of breathing and judgment based on the cycle of heart rate and heart rate displacement.

In the first and second embodiments described above, the physical condition is detected based on the magnitude of the positive and negative peak values with respect to the normal time, but the amplitude at the normal time is stored and the deviation of the difference between the positive and negative peak values is stored. You may make it detect whether it is a fatigue state by seeing. Further, the reference position between the positive and negative peaks in the normal state may be stored and the change in the position of half of the positive and negative peak value may be detected to detect whether or not the person is in the dozing state.

<< Effects of the Invention >> Since the present invention is configured as described above, the sensor is not directly attached to the body of the vehicle occupant, especially the driver.
The physical condition can be detected by detecting an accurate breathing state without giving an uncomfortable feeling or a feeling of pressure to the person to be detected.

[Brief description of drawings]

1 and 2 show a first embodiment of the present invention, in which FIG. 1 is a block diagram showing the constitution of the present invention, and FIG. 2 shows the constitution of microwave transmission / reception sensor signal arithmetic means. FIG. 4 is a block diagram, FIG. 3 is a detection waveform diagram of the signal calculation means of the microwave transmission / reception sensor, and FIG. 4 is a block diagram showing a second embodiment of the present invention. 2 …… Driver (body) 3 …… Microwave Doppler radar sensor (microwave transmission / reception sensor) 4 …… Detection signal calculation means 5 …… Zero cross detector 6 …… Zero cross cycle counter 7 …… Reference frequency Oscillator 8 …… Positive peak hold circuit 9 …… Negative peak hold circuit 10 …… Analog-digital converter (A / D converter) 11 …… Microcomputer (CPU) 14 …… Alarm circuit

Claims (1)

[Claims] 1. A microwave transmission / reception sensor for receiving a reflected wave of a microwave applied to the chest or abdomen of a vehicle occupant, and a signal representing a displacement state of the chest or abdomen from a detection signal received by the microwave transmission / reception sensor. Displacement amount calculating means for calculating, and displacement state detecting means for detecting at least one of the maximum value and the minimum value of the calculated signal in the period, amplitude or predetermined period of the signal calculated by the displacement amount calculating means. A vehicle occupant state detection device comprising: a breathing state comparison unit that compares a value based on a value detected by the displacement state detection unit with a predetermined value.