JP2004290324A - Apparatus for judging vigilance of crew - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To judge a vigilance of a crew by detecting the respiration of the crew of a vehicle. <P>SOLUTION: An apparatus which judges the vigilance of the crew is equipped with a pressure sensor disposed at a part to fix a belt portion of a seat belt to detect the respiration of the crew who sits with the seat belt and a controlling unit to judge the vigilance of the crew based on a detection value by the pressure sensor. The pressure sensor is disposed on a buckle for fixation, a tongue for fixation, a lore anchor for fixation or shoulder anchor for fixation of the seat belt. Thereby a detection value by the pressure sensor with little influence of acceleration can be obtained without depending on somatotype or a posture of the crew. As one embodiment, the controlling unit compares the detection value by the pressure sensor with the standard value which shows the vigilance of the crew and the judges the vigilance of the crew based on the result of the comparison. The comparison can be performed on both a cycle of the detection value by the pressure sensor and stability of the cycle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus that determines the awake state of a vehicle occupant by detecting the breathing of the vehicle occupant.
[0002]
[Prior art]
There has been proposed a method of detecting a dozing state of an occupant using a pressure sensor. For example, the belt portion of the seat belt is provided with a sensor that detects a change in the tension or bending of the belt caused by breathing of the seat belt wearer, the respiratory rate is calculated from the output of the sensor, and the wearer is in a doze state. There has been proposed a method for determining whether or not there is an error. This sensor includes a piezoelectric element or a strain gauge (for example, Patent Document 1).
[0003]
Also, in order to prevent the driver from falling asleep, a closed air bag containing a pressure sensor is provided in a seat portion where the driver's body pressure is applied when the driver sits down, and the driver's body movement is detected. There is a method (for example, Patent Document 2).
[0004]
Furthermore, there is a method in which a sealed air bag in which a pressure sensor is sealed is provided in a belt portion or a seat of a seat belt to collect driver's biological information (for example, Patent Document 3).
[0005]
[Patent Document 1]
Japanese Patent Publication No. 2760019/0006
[Patent Document 2]
JP 2002-187450 A
[Patent Document 3]
JP 2001-286448 A
[Problems to be solved by the invention]
If a sensor is provided in the belt portion of the seat belt, the length of the seat belt varies depending on the physique or posture of the occupant, and therefore the position of the sensor in contact with the occupant may vary. Further, the detection value of the pressure sensor may fluctuate due to a change in the posture in which the occupant sits. Further, when the seat belt is wound up, the sensor may be bulky, and the sensor may be damaged.
[0009]
When a sensor is provided in a belt portion or a seat portion of a seat belt, a detection value of the sensor is easily affected by acceleration. FIG. 13 shows a waveform 101 of the vehicle speed, a waveform 102 of the detection value of the pressure sensor, and a waveform 103 of the acceleration when a pressure sensor is provided on the back of the seat. It can be seen that the detection value of the pressure sensor also changes according to the change of the acceleration. This makes it difficult to extract only the respiratory component from the detection value of the pressure sensor with good accuracy.
[0010]
Therefore, there is a need for a device that can determine the occupant's arousal state without depending on the physique and posture of the occupant. Further, there is a need for a device capable of reducing the influence of acceleration and determining the occupant's arousal state with good accuracy.
[0011]
[Means for Solving the Problems]
According to one aspect of the present invention, a device for judging a passenger's awake state is provided on a portion for fixing a belt portion of a seat belt, and detects a breath of an occupant seated with the seat belt attached thereto. And a control unit for determining the occupant's arousal state based on the detection value of the pressure sensor. According to the present invention, it is possible to determine the awake state of the occupant without depending on the physique and posture of the occupant. Further, since the sensor is provided in a portion of the seat belt for fixing the belt portion, the influence of acceleration can be reduced.
[0012]
In one embodiment of the present invention, the pressure sensor is provided on a buckle for fixing a seat belt.
[0013]
In another embodiment of the present invention, the pressure sensor is provided on a tongue for fixing the seat belt.
[0014]
In another embodiment of the present invention, the pressure sensor is provided on a lower anchor for fixing the seat belt.
[0015]
In another embodiment of the present invention, the pressure sensor is provided on a shoulder anchor for fixing the seat belt.
[0016]
According to one embodiment of the present invention, the pressure sensor includes an air bag, and detects a pressure of air in the air bag. By using an air bag, a favorable gain can be obtained as compared with a strain gauge or a thermistor.
[0017]
In one embodiment of the present invention, the control unit includes a comparator that compares the detected value of the pressure sensor with a reference value indicating the awake state of the occupant. A determination circuit for determining a level.
[0018]
According to one embodiment of the present invention, the reference value is a cycle of a breathing waveform of the occupant when the occupant is awake. The comparator compares the cycle of the respiratory waveform based on the value detected by the pressure sensor with the reference value. By comparing the periods, the level of the occupant's arousal state can be obtained with better accuracy.
[0019]
According to one embodiment of the present invention, the control unit further includes a stability calculation circuit that calculates an index indicating the stability of the cycle of the respiratory waveform based on the detection value of the pressure sensor. The comparator compares the index calculated by the stability calculation circuit with an index indicating the stability of the reference value. By using both the cycle and the index indicating the stability of the cycle, the determination of the arousal state can be made more reliable. Further, the level of the arousal state can be obtained in more detail.
[0020]
According to one embodiment of the present invention, the device for determining the arousal state of the occupant further performs notification to the emergency center in response to the detection of a collision of the vehicle by a collision sensor provided on the vehicle. It is provided with a reporting means. The notification to the emergency center includes transmitting the detected value of the pressure sensor to the emergency center. According to the present invention, when a collision occurs, the condition of the occupant's body can be immediately notified to the emergency center.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an arrangement of a pressure sensor according to one embodiment of the present invention.
[0022]
FIG. 1A shows a state where an occupant wears a seat belt 2 and sits on a seat 1. The occupant wears the seat belt 2 by fitting the tongue 3 attached to the belt portion of the seat belt 2 into the buckle 4. The pressure sensor is provided on the fixing buckle 4.
[0023]
FIG. 1B shows an enlarged view of the fixing buckle 4. FIG. 1C shows a side view of the fixing buckle 4. The pressure sensor 5 includes an air bladder 6 and a pressure-electric converter 7. The air bag 6 is sealed. When the occupant breathes, the tension of the seat belt changes, which changes the pressure of the air in the air bladder 6. The air bag 6 can be made of a confidential flexible metal, rubber, plastic, cloth, paper, or the like.
[0024]
The pressure sensor 5 is inserted between the main body portion 11 of the fixing buckle 4 and the attachment portion 12 provided to face the main body portion 11. The air bag 6 of the pressure sensor 5 is provided so as to be in contact with the main body portion 11 and the attachment portion 12.
[0025]
The bladder 6 is connected to a pressure-electric converter 7 via a tube 8. The pressure-electricity converter 7 outputs the pressure of the air in the air bladder 6 as an electric signal, and the electric signal is sent to a terminal 10 via an electric cord 9. Alternatively, a pressure-to-electric converter 7 may be provided in the bladder 6.
[0026]
FIG. 2 is a diagram showing an arrangement of a pressure sensor according to another embodiment of the present invention. FIG. 2A shows a state in which the occupant is wearing the seat belt 2 and sitting on the seat 1. The pressure sensor 5 is provided on the tongue 3 connected to the belt portion.
[0027]
FIG. 2B shows an enlarged view of the tongue 3. The belt portion 11 of the seat belt 2 is wound around the tongue 3. The pressure sensor 5 includes an air bladder 6 and a pressure-electric converter 7. The air bag 6 is provided between the belt portion 11 and the tongue 3. The air bladder 6 can have a configuration similar to that of FIG.
[0028]
The bladder 6 is connected to a pressure-electric converter 7 via a tube 8. The pressure-electric converter 7 outputs the pressure of the air in the air bladder 6 as an electric signal, and the electric signal is sent to a terminal 10 via an electric cord 9. Alternatively, a pressure-to-electric converter 7 may be provided in the bladder 6.
[0029]
As shown in FIG. 3, the pressure sensor 5 may be provided on the lower anchor 15 for fixing the seat belt 2 or the shoulder anchor 16 for fixing. The pressure sensor 5 can be attached to these anchors using the attachment technique of FIG.
[0030]
In this manner, by providing the pressure sensor at the portion where the belt portion of the seat belt is fixed, it is possible to detect the pulsation of breathing of the occupant without depending on the physique and posture of the occupant.
[0031]
FIG. 4 is an example of a circuit connected to the pressure sensor 5 according to one embodiment of the present invention. The electric signal from the pressure sensor 5 is amplified by the amplifier circuit 17 via the terminal 10 shown in FIG. From the amplified electric signal, high frequency noise and the like are removed by the filter 18.
[0032]
The output of the filter 18 is passed to a control unit 19. The control unit 19 determines the occupant's awake state based on the detection value of the pressure sensor 5.
[0033]
FIG. 5 shows the occupant's breathing waveforms 21 and 22 detected by sensors using a thermistor and a strain gauge according to a conventional method, and the occupant detected by a pressure sensor 5 using an air bladder according to an embodiment of the present invention. Is shown. It can be seen that good gain can be obtained by detecting respiratory pulsation with a sensor using an air bag.
[0034]
FIG. 6 shows a waveform 24 of the acceleration detected by the acceleration sensor and a waveform 25 of the detection value of the pressure sensor 5 output from the filter 18 according to the embodiment of the present invention. It can be seen that the influence of the acceleration on the detection value of the pressure sensor 5 is reduced. Thus, by arranging the pressure sensor 5 as shown in FIGS. 1 to 3, the pulsation of the occupant's breathing can be detected satisfactorily without being affected by the acceleration through the change in the stress of the seat belt. can do.
[0035]
A waveform 25 shown in FIG. 6 is a waveform of the detection value of the pressure sensor 5 output from the filter 18 when the occupant is in the awake state. FIG. 7 shows a waveform 26 of the detection value of the pressure sensor 5 output from the filter 18 when the occupant's arousal level is decreasing. As is clear from comparison between the waveforms 25 and 26, when the occupant's arousal level decreases, the cycle of the respiratory waveform increases.
[0036]
FIG. 8 shows an example of the average value of the cycle of the respiratory waveform and the standard deviation of the cycle of the respiratory waveform according to the awake state of the occupant. Reference numerals 31 and 32 indicate the average value of the cycle of the respiratory waveform and the standard deviation of the cycle when the occupant is awake on the general road, respectively. The average period is 3.16 seconds and the standard deviation is 0.34. Respiration is relatively stable and thus has a relatively low standard deviation.
[0037]
Reference numerals 33 and 34 indicate the average value of the cycle of the respiratory waveform and the standard deviation of the cycle when the occupant's arousal level is decreasing on the highway. The average period is 3.95 seconds, which is longer than the average period 31 in the awake state. On a highway, a tension state due to a lane change, a brake operation, or the like may occur, and thus the arousal level varies. Thus, the standard deviation is 0.58, which is larger than the standard deviation 32 of the general road.
[0038]
Reference numerals 35 and 36 indicate the average value of the cycle of the respiratory waveform and the standard deviation of the cycle when the occupant is dozing on the highway and the general road, respectively. The average period is 4.39 seconds, which is longer than the average period 31 in the awake state and the average period 33 in the awake state. Since the user is dozing, the standard deviation is 0.21 and the variation is considerably small.
[0039]
Thus, as the arousal level decreases, the period of the respiratory waveform increases. In particular, in the dozing state, the average period is longer than one second as compared with the awake state. Therefore, the arousal state can be determined by observing the cycle.
[0040]
It can also be seen that the dozing state has a longer cycle and a smaller standard deviation than the awake state. Furthermore, when the period is longer and the standard deviation is higher than in the awake state, it can be seen that the arousal level may have already decreased. As described above, by observing the cycle and the standard deviation of the respiratory waveform, it is possible to determine a dozing state and a state in which the degree of awakening is reduced.
[0041]
FIG. 9 is a functional block diagram of control unit 19 for determining the occupant's arousal state according to one embodiment of the present invention. The functional blocks can be realized by hardware and / or software.
[0042]
The analog / digital converter 21 converts an output signal from the filter 18 into a digital value. The cycle detection circuit 22 calculates the cycle of the detection value of the pressure sensor 5 by detecting the maximum value (or the minimum value) of the detection value of the pressure sensor 5. The averaging circuit 23 calculates an average value of a cycle detected over a predetermined time. The moving average method may be used as a method for calculating the average value.
[0043]
The memory 29 stores, as a reference cycle, an average value of the cycle of the respiratory waveform detected in advance by the pressure sensor 5 when the occupant is awake. The first comparator 24 compares the detection cycle received from the averaging circuit 23 with the reference cycle stored in the memory 29.
[0044]
The determination circuit 27 determines the occupant's arousal state based on the comparison result of the first comparator 24. Specifically, if the detected average cycle is longer than the reference cycle and the difference between the two is equal to or more than a predetermined value (for example, 1 second in the example of FIG. 8), it is determined that the user is dozing. If the detected average cycle is longer than the reference cycle and the difference between the two is less than the predetermined value, it is determined that the arousal level has decreased.
[0045]
The warning unit 28 can issue a warning to the occupant when it is determined that the vehicle is dozing or the state of awakening is reduced. The alarm can be issued using, for example, sound or vibration. Different alarms may be issued depending on the dozing state and the state in which the arousal level is reduced.
[0046]
FIG. 10 is a functional block diagram of control unit 19 for determining a passenger's awake state according to another embodiment of the present invention. Only parts different from FIG. 9 will be described.
[0047]
A stability calculation circuit 25 is provided, and the stability calculation circuit 25 calculates the stability based on the detection cycle. The stability indicates the degree of variation in the detection cycle, and in this embodiment, the stability is expressed using a standard deviation. Alternatively, the stability may be expressed by using another index (for example, variance expressed by the square of the standard deviation). The standard deviation calculated based on the reference cycle is stored in the memory 29 as the reference standard deviation. The second comparator 26 compares the standard deviation received from the stability calculation circuit 25 with a reference standard deviation.
[0048]
The determination circuit 27 determines the occupant's arousal state based on the comparison result of the first comparator 24 and the second comparator 26. Specifically, if the detected average cycle is longer than the reference cycle and the standard deviation of the detected cycle is lower than the reference standard deviation, it is determined that the occupant is dozing. If the detected average cycle is longer than the reference cycle and the standard deviation of the detected cycle is higher than the reference standard deviation, it is determined that the occupant's arousal level may have already decreased.
[0049]
In other embodiments, the decision circuit 27 can monitor the average period of the occupant's respiratory waveform. If the average cycle is gradually longer, it can be determined that the occupant's arousal level is gradually decreasing. Similarly, the decision circuit 27 can monitor the standard deviation of the cycle of the occupant's respiratory waveform. When the standard deviation is gradually decreasing, it can be determined that the occupant's arousal level is gradually decreasing. By such monitoring, an alarm can be issued to alert the occupant before the occupant falls asleep.
[0050]
In still another embodiment, the determination circuit 27 can use the average period and the standard deviation to set the level of the arousal level. The alarm unit 28 can issue different alarms according to the set level of the alertness.
[0051]
As an example, if the average cycle of the occupant's breathing waveform is longer than the reference cycle by a predetermined value and the standard deviation is lower than the standard standard deviation, a value “4” is set as the level indicating the dozing state. If the average cycle is longer than the reference cycle and the standard deviation is higher than the reference standard deviation, it indicates that the awakening degree may have already decreased, and the level value “3” is set. Regardless of the standard deviation, if the cycle is gradually increasing, it indicates a state in which the arousal level is gradually decreasing, and the level value “2” is set. If the cycle is close to the reference cycle and the standard deviation is also close to the reference standard deviation, it indicates that the occupant is awake, and the level value “1” is set.
[0052]
The alarm unit 28 can issue different alarms according to the set alertness level. For example, if the level value is 4 or 3, a relatively strong alarm (for example, a strong vibration or a loud sound) can be issued. If the value of the level is 2, the occupant can be alerted by voice and the occupant can be prevented from falling into a state of reduced alertness.
[0053]
FIG. 11 is a functional block diagram of the control unit 19 according to another embodiment of the present invention. The difference from FIG. 10 is that the control unit 19 operates in cooperation with the navigation system. In the memory 41, the average cycle and the standard deviation when the occupant is driving on a general road in the awake state are stored as standard values for general roads. Further, in the memory 41, the average period and the standard deviation when the occupant is driving on the highway in the awake state are stored as reference values for the highway.
[0054]
The reference value extraction unit 43 uses information from the navigation system 42 to determine whether the currently traveling road is a general road or an expressway. If it is a general road, a general road reference value is extracted from the memory 41 and passed to the first and second comparators 24 and 26, respectively. If it is a highway, a highway reference value is extracted from the memory 41 and passed to the first and second comparators 24 and 26, respectively.
[0055]
The determination circuit 27 determines the awake state of the occupant based on the comparison result of the first and second comparators, as described above. As described above, since the reference value is set according to the state of the road, it is possible to more appropriately determine the occupant's arousal level.
[0056]
In another embodiment, the reference value can be changed according to road conditions based on information from the navigation system 42. For example, when it is determined that the vehicle is traveling on a potentially dangerous road (for example, a mountain road), the reference value for the average cycle can be set shorter, and the reference value for the standard deviation can be set higher. . Thereby, the occupant can be encouraged to have a more severe alertness.
[0057]
The awake state determination device according to the present invention can be used to detect the state of an occupant in an emergency. FIG. 12 shows an example of such an emergency notification device.
[0058]
The control unit 19 receives a signal indicating the awake state of the occupant. On the other hand, the vehicle is provided with a collision sensor 51, and the collision sensor 51 detects a collision of the vehicle with any object. If a collision is detected, the collision processing unit 52 performs processing such as activation of the airbag.
[0059]
The notification unit 53 automatically performs notification to the emergency center in response to activation of the airbag and the like. At this time, the notification unit 53 acquires the occupant's respiratory waveform data from the control unit 19 and transmits the respiratory waveform data to the emergency center. Thereby, the emergency center can know in advance the degree of injury of the occupant. The reporting unit 53 can report the personal data (name, address, etc.) of the occupant stored in the memory in advance to the emergency center, the police, and the like. Further, when the navigation system is mounted, data on the current position of the vehicle can be reported to an emergency center, police, and the like.
[0060]
The notification can be performed by any suitable means. For example, the notification can be made by calling an emergency center registered in the storage device in advance by radio.
[0061]
【The invention's effect】
According to the present invention, the awake state of the occupant can be determined with better accuracy.
[Brief description of the drawings]
FIG. 1 is a diagram showing an arrangement and a structure of a pressure sensor according to an embodiment of the present invention.
FIG. 2 is a diagram showing an arrangement and a structure of a pressure sensor according to another embodiment of the present invention.
FIG. 3 is a diagram showing an arrangement of a pressure sensor according to another embodiment of the present invention.
FIG. 4 is a configuration diagram of a circuit connected to a pressure sensor according to an embodiment of the present invention.
FIG. 5 is a diagram showing output waveforms of a pressure sensor using a thermistor, a strain gauge, and an air bag according to an embodiment of the present invention.
FIG. 6 is a diagram showing a waveform of the acceleration of the vehicle and a respiratory waveform when the occupant is in an awake state.
FIG. 7 is a diagram showing a respiratory waveform when the occupant's awake state is reduced.
FIG. 8 is a diagram showing an average cycle and a standard deviation of a respiratory waveform according to an occupant's arousal state.
FIG. 9 is a functional block diagram of a control unit that determines an awake state of an occupant according to an embodiment of the present invention.
FIG. 10 is a functional block diagram of a control unit that determines a passenger's arousal state according to another embodiment of the present invention.
FIG. 11 is a functional block diagram of a control unit that determines the occupant's awake state in cooperation with a navigation system according to another embodiment of the present invention.
FIG. 12 is a functional block diagram of the emergency notification device in cooperation with the awake state determination device according to the embodiment of the present invention.
FIG. 13 is a diagram showing a waveform of a detection value of the pressure sensor affected by acceleration when the pressure sensor is provided on the back of the seat.
[Explanation of symbols]
3 Tongue 4 Buckle 5 Pressure sensor 6 Air bag 15 Lower anchor 16 Shoulder anchor

Claims (10)

A pressure sensor provided at a portion for fixing a belt portion of the seat belt, and detecting a breath of an occupant seated with the seat belt;
A control unit that determines the awake state of the occupant based on the detection value of the pressure sensor;
A device for determining the arousal state of an occupant, comprising: The device for judging the arousal state of an occupant according to claim 1, wherein the pressure sensor is provided on a buckle for fixing the seat belt. The device for judging the occupant's awake state according to claim 1, wherein the pressure sensor is provided on a fixing tongue of the seat belt. The device for judging the occupant's alertness according to claim 1, wherein the pressure sensor is provided on a lower anchor for fixing the seat belt. The device for judging the occupant's arousal state according to claim 1, wherein the pressure sensor is provided on a fixing shoulder anchor of the seat belt. The device for judging the occupant's arousal state according to claim 1, wherein the pressure sensor includes an air bag, and detects a pressure of air in the air bag. The control unit further comprises:
A comparator that compares a detection value of the pressure sensor with a reference value indicating the awake state of the occupant;
A determination circuit that determines a level of the occupant's arousal state based on a comparison result of the comparator;
The device for judging the occupant's alertness according to claim 1, further comprising: The reference value is a cycle of a breathing waveform of the occupant when the occupant is in an awake state,
The device for judging the occupant's arousal state according to claim 7, wherein the comparator compares a cycle of a respiratory waveform based on a detection value of the pressure sensor with the reference value. The control unit further comprises:
A stability calculation circuit that calculates an index representing the stability of the cycle of the respiratory waveform based on the detection value of the pressure sensor,
9. The device for judging the occupant's alertness according to claim 8, wherein the comparator compares the index calculated by the stability calculation circuit with an index indicating the stability of the reference value. In addition, in response to detection of the collision of the vehicle by a collision sensor provided in the vehicle, further comprising a notification means for performing a notification to the emergency center,
The device for determining an occupant's alertness according to claim 1, wherein the notification to the emergency center includes transmitting a detection value of the pressure sensor to the emergency center.

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