JPH01115344A - Apparatus for detecting state of driver - Google Patents

Abstract

PURPOSE:To indirectly know the state of the body without directly bringing a sensor into contact with the body by receiving the reflected wave of the microwave emitted toward the breast of a driver and checking the respiratory state detected from the cycle or peak value of the receiving signal. CONSTITUTION:When a microwave of 10GHz is allowed to irradiate the breast of a driver 2 from a sensor 3, the microwave transmits through the clothing of the driver to reach the surface of his breast and is reflected to be again received by the sensor 3. The receiving wave is processed by a detection signal operating means 4 to obtain the waveform signal corresponding to the displacement quantity of the breast. The data such as the respiratory cycle, positive peak value and negative peak value of the driver at a normal time are preliminarily stored in a CPU 11 and compared with the respiratory cycle and the positive and negative peak values inputted from a zero cross cycle counter 5 and an A/D converter 10 and judged. When a rapid respiratory cycle or the like is judged, that is, it is judged that the driver is in a fatigue state, an alarm is emitted from an alarm circuit 14.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vehicle occupant condition detection device suitable for detecting the physical condition of a vehicle occupant, particularly a vehicle driver.

(Prior art) Conventionally, in order to drive a vehicle safely, as a means of grasping the physical condition of the driver, abnormal steering operation patterns caused by drowsy driving etc. are memorized and the actual steering angle changes are recorded. An abnormal state detection device for a driver has been proposed, which compares the above patterns and, when they match or are similar, determines that the pattern is an abnormal state such as dozing off, and issues an alarm.

Furthermore, a grip pressure detection element is provided on the driver's steering wheel, and when the grip pressure decreases after a predetermined period of time,
A device that issues a warning to the driver has also been proposed.

Additionally, a device has been proposed in which a fingertip pressure detector that detects the heartbeat condition is attached to the driver's thumb or the like, and the driver's physical condition can be determined from the heartbeat condition and a warning can be issued. (Japanese Unexamined Patent Publication No. 60-76428).

(Problems to be Solved by the Invention) However, when directly measuring the state of the body as in the prior art described above, there is the inconvenience of having to attach the detection element directly to the body, and the problem of attaching the detection element to the body. Due to the psychological pressure or discomfort of attaching the device, there is an inconvenience in that accurate respiration rate or heart rate cannot be measured.

Furthermore, in the method of detecting the steering operation state to understand the driver's condition, the patterns of steering operation due to drowsiness are complex and diverse, and do not necessarily match the patterns preset in the storage means.
There was a problem that the detection accuracy was not very good.

In addition, when it comes to grasping the driver's condition by detecting the grip pressure on the steering wheel, the grip pressure on the steering wheel naturally changes, especially when driving at high speeds on straight routes or when driving in traffic jams, so it is difficult to accurately determine the driver's condition. Furthermore, since the way the driver grips the steering wheel varies greatly depending on the person, there is a drawback that the driver's condition cannot be properly determined.

Furthermore, devices equipped with fingertip pressure detection needles have the disadvantage that they give the driver a sense of discomfort, and if the driver removes the sensor, no detection is possible. .

(Object of the Invention) The present invention was made to solve the above problems, and its purpose is to indirectly detect the state of the body without directly contacting the body with a sensor. A device for detecting the condition of vehicle occupants that can detect

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a microwave transmitting/receiving sensor that receives reflected waves of microwaves irradiated to the chest or abdomen of a vehicle occupant, and displacement calculating means for calculating a signal representing the displacement state of the chest or abdomen from the detection signal received by the transmitting/receiving sensor; and the period and amplitude of the signal calculated by the displacement calculating means, or the calculated signal in a predetermined period. displacement state detection means for detecting at least one of the maximum value or minimum value of the displacement state detection means; and breathing state comparison means for comparing a value based on the value detected by the displacement state detection means with a predetermined value. It is characterized by this.

(Function) With the above configuration, the present invention receives reflected waves of microwaves emitted toward the chest of a vehicle occupant, particularly the driver, detects a signal representing the displacement state of the chest, and detects a signal with a period of ε. Alternatively, the physical condition is detected based on the respiratory condition detected from the peak value.

(Embodiment) Hereinafter, as an embodiment of the present invention, an embodiment for detecting an abnormal state of the body of a vehicle driver will be described based on the drawings.

Before explaining based on the drawings, in order to facilitate understanding of the present invention, the relationship between the driver's physical condition, respiratory condition, and steering angle will be explained.

First, a driver changes lanes while driving in an urban area.

When making a right or left turn, the driver is in a nervous state and will not doze off. Therefore, if the steering angle is large, it is assumed that the driver is not dozing off. When the angle is smaller than a predetermined value, and the respiratory cycle is at rest as brain cells are at rest, the amount of oxygen required decreases and becomes slower than normal, so-called breathing fluctuations tend to slow down, and the breathing cycle also slows down. The maximum value of inspiration (positive peak value) and the maximum value of expiration (negative peak value) of the processed displacement signal based on the amplitude (described later) tend to be smaller than normal, but the negative peak value is larger. I'm in the middle of the day.

Additionally, when a driver becomes fatigued, their breathing cycle tends to become more regular as their autonomy increases, and the amplitude of their breathing tends to become shallower, so the positive and negative peak values are lower than normal. becomes smaller.

Furthermore, when a driver is under extreme stress or has an abnormal heart condition, the amplitude of their breathing may become smaller (breathing becomes shallower), and their breathing cycle may become faster or slower. The breathing cycle becomes disrupted, and its tendency becomes irregular rather than constant.

Therefore, if the above-mentioned tendency can be detected accurately, the driver's physical condition can be accurately grasped, and if an abnormal condition is known, appropriate measures can be taken for the driver or fellow passenger.

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

3 is a microwave Doppler radar sensor (hereinafter referred to as "sensor") as a microwave transmitting/receiving sensor.
It is possible to transmit microwaves in the 10Gt-12 band onto the chest of the driver 2 and to receive the reflected waves.

Reference numeral 4 denotes a detection signal calculation means for calculating the signal received by the sensor 3, which calculates the amount of displacement corresponding to the displacement of the chest epidermis due to breathing and movement of blood vessels. That is,
Microwaves emitted from the sensor 3 calculate an arch in which the distance between the sensor and the body changes due to contraction and expansion of blood vessels associated with breathing or heart movement.

In the figure, the gap/cross detector 5 detects the point where the reflected wave intersects the reference line, and the comparison between this intersection position and the reference frequency from the M quasi-frequency oscillator 7, that is, the intersection position Depending on how many times the reference frequency is oscillated during the
A cross period counter 6 detects the period of respiration.

8 and 9 are means for detecting the amplitude of respiration,
It consists of a positive peak hold circuit and a negative peak hold circuit, and is designed to hold each maximum value signal for a predetermined time, and these signals are sent to a microcomputer (via an analog-to-digital (A/D) C
PU) 11.

Reference numeral 15 in the figure indicates a steering wheel, and this steering angle is necessarily detected by a steering angle sensor 12, and this detection signal is sent to a steering comparison circuit 13 that compares the steering angle during driving with a predetermined value. After that, an output signal is input to the CPU 11 when the steering angle is less than a predetermined value.

The CPU 11 is driven by a built-in system ROM, and the steering angle is below a predetermined value when the driver is in a normal state, that is, when the driver is in a relaxed state such as immediately after starting the engine.

), the positive and negative peak values and periods of respiration are pre-stored in RAM, and the respiration period and A/D conversion input from the zero-cross period counter 6 when the steering angle during driving is below a predetermined value. The positive and negative peak values inputted from the device 10 are compared and calculated.

In addition, 14 in the figure is based on the result of the comparison operation.
This is an alarm circuit that alerts the driver when urine is detected.

FIG. 2 shows a detailed block diagram of the detected signal calculation means 4. As shown in FIG. That is, this detection signal calculation means 4 adopts a two-phase displacement detection method, and has two phases 20a and 20a.
0b is a detector provided at a predetermined interval on the waveguide between the microwave oscillator 21a and the horn antenna 21b, which generate two types of microwaves in the 10GI-fz band having a phase difference of π/2. The signals detected by these detectors 20a and 20b are sent to bypass filters 22 and 23, respectively.
After removing the direct current component due to the reflected wave from a stationary object in the background of the body, it is input to the first and second absolute value circuits 24 and 25, and is operated at the reference oscillation frequency of sinωt of the three-phase oscillation circuit 26. The signal is inputted to a second multiplier circuit 28 which operates from the reference oscillation frequency of CO3ωt of the third multiplier circuit 27 and the three-phase oscillation circuit 26.

Furthermore, the output signals of the bypass filters 22 and 23 are
A three-phase oscillation circuit 26 multiplied by a multiplier circuit 29
After passing through an oscillation signal cutter 30 that switches the reference oscillation frequency between sinωt and -5inωt, the signal is multiplied by the output signal of the first absolute value circuit 24 and a third multiplier circuit 31.

Further, the output signal of the second absolute value circuit 25 is transmitted to the third multiplication circuit 3 through a fourth multiplication circuit 32 which operates based on the reference oscillation frequency of COSωt of the three-phase oscillation circuit 26.
1 output signal is subjected to addition processing in a first addition circuit 33.

On the other hand, the output signals of the first multiplier circuit 27 and the second multiplier circuit 28 are added to the second adder 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, 31, and 32, the three-phase oscillation circuit 26, and the oscillation signal switching circuit 30 divide the approximation calculation into two systems for determining the distance from the sensor 3 to the chest determined by a function such as a sine wave. is being carried out. Also, addition circuit 3
3.34, two signals with different phases are synthesized.

The output signal of the first addition circuit 33 is transmitted to the waveform shaping circuit 36.
．． The signal is subjected to ffi processing by the phased locked loop circuit 37 and the delay circuit 38 so as to be synchronized with the output signal of the second adder circuit 34, and is sent to the sample and hold circuit 35.

The sample-and-hold circuit 35 extracts the synchronously detected waveform and sends it to means for detecting the breathing cycle and depth of breathing, which will be described later.

FIG. 3 shows the state of detection in the detection calculation means 4, in which (a) shows the waveform obtained by processing the signal received by the detector 20a, and (b) shows the waveform obtained by processing the signal received by the detector 20a. This shows a signal obtained by receiving and processing a signal with a phase difference of π/2 by the detector 2ob.

By combining the waveforms in (a) and (b>) above, the waveform on the left side of the figure (C) is obtained.

In other words, according to the two-phase displacement method, the amount of displacement can be detected without creating a low sensitivity region near the reference position that occurs due to the sensitivity characteristics peculiar to the detector when only one phase of microwave is irradiated. For example, it is also possible to accurately detect the amount of displacement in the movement of blood vessels associated with the beating of the heart, which is shown by the whiskers appearing on the waveform in FIG. In addition, the same figure (
The right part of C) 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 this embodiment having the above configuration, when microwaves in the 10 GHz band are irradiated from the sensor 3 toward the chest of the driver 2, the microwaves pass through the driver's clothing, reach the surface of the chest, and are reflected, and the microwaves are emitted again to the sensor. Received by 3.

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 finds the intersection point with a reference position set approximately halfway between the positive and negative peaks during normal operation, and the zero cross point is detected from between the intersection points. A period counter 6 detects the breathing period. Further, the detection signal from the detection signal calculation circuit 4 is detected in a positive peak hold circuit 8 and a negative peak hold circuit 9, and is sent to the CP via an A/D converter 10.
The positive peak value and negative peak value are input to U11 and detected.

The CPU II stores in advance the breathing cycle, positive peak value, and negative peak value data of the driver in a normal state, for example, in a relaxed state immediately after starting the engine. A/D conversion 51
Compare and judge the breathing cycle input from 0 with the positive and negative peak values, for example, if the breathing cycle is larger than normal, or if the positive peak value is smaller and the negative peak value is larger than normal. If this tendency is shown, it is determined that the driver is dozing, and the alarm circuit 14 issues an alarm to the driver or fellow passenger.

On the other hand, the breathing cycle becomes faster or positive.

When the negative peak value becomes small, it is determined that the driver is in a fatigued state, and the alarm circuit 14 issues a warning.

In addition, when the positive and negative peak values become smaller (breathing becomes shallower) or the breathing cycle becomes faster or shorter, the breathing cycle is disrupted, and when the tendency is not constant and becomes disrupted, the driver It is determined that the patient is in a state of extreme stress or an abnormal state of the heart system, and an alarm is issued from the alarm circuit. Note that if such a state shows a tendency to return to a normal level within a few seconds, there is no problem, so no alarm should be issued.

Therefore, according to this embodiment, the respiratory state of the driver's body is detected indirectly by the respiratory cycle and positive/negative peaks without direct contact with the device, and the detected state is compared with the normal state to determine whether it is an abnormal state. If there is an abnormal condition, a warning will be given to that effect.

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 calculation circuit 4 is passed through the low-pass filter 16 and then By performing the processing shown in the embodiment 1, the period of displacement due to breathing alone and the positive and negative peak values are detected, and the output signal of the above-mentioned detection calculation circuit 14 is passed through the bypass filter 17 at the zero cross point.・The detector 5' detects the intersection with the reference position, and by comparing this intersection with the reference frequency input from the reference frequency generator 7'', the zero-cross period counter 6- detects the period of the heartbeat displacement amount. .

In detecting the period of the heartbeat displacement, large waves are removed by the bypass filter from the output waveform of the detection calculation circuit 4, and only rapid waves, that is, high-frequency waves are detected.

That is, large changes in the chest caused by breathing are removed, and heartbeats caused by the movement of the heart caused by the movement of blood vessels can be detected. In other words, only the whisker-shaped signal in FIG. 3(C) can be extracted.

That is, in a state of extreme stress or when the heart system is abnormal, the respiratory cycle becomes faster, the heartbeat cycle becomes faster, and the heart rate increases. Then, by comparing the heart rate within a predetermined period of time under normal conditions, it is possible to determine whether or not there is an abnormal state and issue an alarm.

Therefore, since the second embodiment has a configuration for detecting the heartbeat state in addition to the configuration of the first embodiment, the CPU has in advance stored the driver's normal breathing cycle, positive and negative peak values, and heart rate. By memorizing the cycle, it is possible to compare and judge the driver's breathing and heartbeat conditions to determine whether or not there is an abnormality.
The physical condition of the driver can be detected with greater safety.

Particularly in the case of extreme stress or cardiac abnormalities, a double safety measure can be taken by making judgments based on the breathing cycle and amplitude and judgments based on the heart rate and heart rate displacement period.

In addition, the above-mentioned 1. In the second embodiment, the physical condition is detected based on the magnitude of the positive and negative peak values with respect to the normal state.
The normal amplitude may be stored and the deviation of the difference between positive and negative peak values may be observed to detect whether or not the person is in a fatigued state. Alternatively, a reference position between positive and negative peaks during normal times may be stored, and a change in position that is half of the positive and negative peak values may be used to detect whether or not the person is in a dozing state.

(Effects of the Invention) Since the present invention is configured as described above, there is no heavy load, especially since there is no need to attach a sensor directly to the driver's body.
The body condition can be detected by accurately detecting the breathing condition without giving unnecessary discomfort or pressure to the person to be detected.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 shows the configuration of the microwave transmitting/receiving sensor signal screening means. FIG. 3 is a detection waveform diagram of the signal calculation means of the microwave transmitting/receiving 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... U-port cross detector 6... Zero cross Period 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 patent applicant Suzuki, Nissan Automushi Co., Ltd. Representative Patent attorney Kazu 1) Seinori

Claims (1)

[Claims] (1) A microwave transmitting/receiving sensor that receives reflected waves of microwaves irradiated to the chest or abdomen of a vehicle occupant, and a signal representing the displacement state of the chest or abdomen is calculated from the detection signal received by the microwave transmitting/receiving sensor. displacement amount calculation means; displacement state detection means for detecting at least one value of the period and amplitude of the signal calculated by the displacement amount calculation means, or the maximum value or minimum value of the calculated signal in a predetermined period; A vehicle occupant condition detection device comprising: breathing condition comparison means for comparing a value based on the value detected by the displacement condition detection means with a predetermined value.