JP5196191B2 - Biological sensing device for vehicles - Google Patents

Description

  The present invention relates to a biological sensing device for a vehicle that is mounted on a vehicle and acquires biological information of an occupant.

  In recent years, a biological sensing device for a vehicle has been devised for knowing a driver's health condition while driving a car. In a vehicle biosensing device, for example, a driver's heartbeat (biological information) while driving a vehicle is detected, and based on the heartbeat, a driver's health state such as drowsiness, fatigue, a feeling of irritation or arrhythmia is determined. It can be a clue. Then, the driver, the manager of the car, and the like know the change in the physical condition, and can take subsequent actions such as changing the driving with another person or taking a break. Thus, the biological sensing device for a vehicle can contribute to safety during driving of an automobile or the like.

  Regardless of whether it is in-vehicle or not, when a minute signal such as a sensor signal is handled, how to set GND (ground) as a reference potential is an important point. In order to measure biological information, many methods for measuring minute displacements and potentials have been devised, but GND serving as a reference for any measurement is an important point. However, it is extremely difficult to ensure a stable GND in a traveling vehicle (details will be described later).

  Although it is possible to secure the GND potential by bringing the sensor (occupant) into contact with a specific part, the problem is that the conscious operation of the subject is required and the occupant feels annoyed. There is also. Therefore, an electrocardiographic sensor equipped with a ground electrode for determining a reference potential on the sheet has been devised (see Patent Document 1).

  In addition, a sensor system using a method of canceling noise at a measurement site by detecting noise at an electrostatic potential (reference potential) has been devised (see Patent Document 2).

  In addition, as another method, there is also disclosed a method of setting an intermediate potential by floating GND and using it as a reference for an object to be measured in a pulse wave meter (refer to Non-Patent Document 1). .

JP 2009-050679 A US Patent 7,466,148 (WO / 2006/007573)

Private laboratory "Biological measurement and electronic work" Electronic circuit part of infrared pulse wave meter (http://www.neo-tech-lab.com/IRHRM.htm), retrieved on July 23, 2009.

  In the example of Patent Document 1, the ground electrode is composed of conductive thread sewn into the seat, and when using non-conductive leather as the seat material, there is a problem that the ground electrode cannot be attached. is there. Even if it can be sewn, there is a problem that the color of the leather is different from the color of the conductive thread, or the appearance is deteriorated by making a hole in the leather. Further, even when a conductive thread is used as a thread for sewing leather, the seam does not necessarily contact the occupant (usually, the seam is difficult to contact the occupant) and does not serve as a ground electrode. Furthermore, since the tactile sensation is different between the conductive yarn and the leather, it may affect the ride comfort.

  In addition, in the example of Patent Document 2, a noise canceling method in an actual vehicle mounted state is not disclosed or suggested, but a method of laying a conductive plate or the like on the seat portion or the back portion is employed in the experiment. In this case as well, there is a problem that the conductive plate cannot be attached when non-conductive leather is used for the seat material.

  In the example of Non-Patent Document 1, a circuit for setting the intermediate potential is required, which causes a problem that the circuit configuration is complicated and the cost of the apparatus increases.

  Against the background of the above problems, an object of the present invention is to provide a vehicular sensing device that can set a stable sensor reference potential regardless of the material of the seat and can detect a sensor signal with high accuracy without being affected by noise. It is to provide.

Means for Solving the Problems and Effects of the Invention

A biological sensing device for a vehicle for solving the above problems includes a bioelectric signal detection unit that detects a bioelectric signal of an occupant seated in a vehicle seat, an occupant potential detection unit that detects an occupant potential, and a cable. and the vehicle ground potential electrode which is grounded to the ground potential of the vehicle Te, by using a potential difference between the ground potential of the occupant's potential and the vehicle, the noise removing unit removes noise superimposed on the passenger potential, and outputs a reference potential signal And a signal processing unit that performs signal processing on the bioelectric signal by the reference potential signal and acquires occupant biometric information, and the occupant potential detection unit and the vehicle ground potential electrode are spaced at a predetermined interval, A seat belt provided in a seat is attached to a place where the seat belt and an occupant come into contact with each other.

  With the above configuration, a stable sensor reference potential can be set regardless of the seat material, and a highly accurate sensor signal that is not affected by noise can be detected. In recent years, in addition to the driver's seat and front passenger seat, it has been required to wear a seat belt in the rear seat. The fact that biometric information cannot be detected without wearing a seat belt seems to reduce the convenience of the passenger, but conversely also has the effect of promoting the wearing of the seat belt. Furthermore, when leather is used for the seat, it does not impair the aesthetic appearance or affect the ride comfort.

Moreover, the passenger | crew potential detection part and vehicle ground potential electrode in the biological sensing apparatus for vehicles of this invention are attached to the lap belt part of the seatbelt at predetermined intervals .

With the above configuration, a stable reference potential of the sensor can be obtained without being affected by noise in a portion corresponding to the potential difference between the occupant potential and the vehicle ground potential .

Moreover, the passenger | crew potential detection part and vehicle ground potential electrode in the biosensor for vehicles of this invention are each comprised as a surface electrode attached to the seatbelt.

  With the above configuration, for example, if the surface electrode is attached to the back side of the seat belt (the surface in contact with the occupant), it is possible to minimize damage to the aesthetics and design in the vehicle when the seat belt is mounted.

Moreover, the passenger | crew potential detection part and vehicle ground potential electrode in the biosensor for vehicles of this invention are each comprised as an electroconductive member woven in at least one part of the seatbelt.

  With the above configuration, for example, if the conductive member has the same color as the seat belt, the aesthetics and design in the vehicle will not be damaged when the seat belt is worn. Furthermore, it is possible to prevent each detection unit from being caught on the occupant's clothes or the like when the seat belt is pulled out / taken up.

  Further, the bioelectric signal detection unit in the vehicle biosensing device of the present invention includes a plurality of electrodes that are attached to a vehicle seat and detect a potential signal emitted from each part of an occupant seated on the seat, each electrode being The bioelectric signal of the passenger is detected by amplifying the difference signal of the detected potential signal.

  With the configuration described above, for example, a bioelectric signal such as an electrocardiogram or a myoelectric potential can be accurately detected with little noise.

Further, the bioelectric signal detection unit in the vehicle biosensing device of the present invention is disposed on the seat so as to be on the left side and the right side of the back of the occupant .

  With the configuration described above, for example, a bioelectric signal such as a pulse wave can be accurately detected with little noise.

The system block diagram of the biometric sensing apparatus for vehicles. The figure which shows the attachment structure of the electrode to a seatbelt. The figure which shows the detailed example of attachment of the electrode to a seatbelt. The figure which shows the other example of FIG. The figure which shows the other example of FIG. The figure which shows the other example of FIG. Sectional drawing of the seatbelt which shows the detail of the attachment structure of the electrode to a seatbelt. The figure which shows the other example of FIG. The figure which shows the other example of FIG. The figure which shows the structure of a sensor system. The figure which shows the outline of an effect | action of a ground detection circuit. The figure which shows the waveform of the electrocardiogram signal detected by the structure of the prior art. The figure which shows the waveform of the electrocardiogram signal detected by the structure of this invention. The figure which shows the structure of a pulse wave sensor.

Hereinafter, the biological sensing device for vehicles of the present invention is explained using a drawing. In FIG. 1, the system block diagram of the biosensor 1 for vehicles is shown. The biological sensing device 1 for a vehicle is attached to a seat 200 and electrodes 31 and 41 for detecting a bioelectric signal of a passenger (driver in the example of FIG. 1) 10 (that is, a potential signal emitted from each part of the passenger). An electrode 72 attached to the seat belt 201 for detecting an occupant potential representing the occupant potential ; an electrode 71 also attached to the seat belt 201 and grounded to the vehicle ground potential (see FIG. 2 for details); The sensor system 28 is configured to detect the biological information of the occupant 10 based on the detected bioelectric signal. The electrode 71 corresponds to the vehicle ground potential electrode of the present invention. The electrode 72 corresponds to the occupant potential detection unit of the present invention.

  The configuration of the electrodes 71 and 72 attached to the seat belt 201 will be described with reference to FIG. From the retractor 208 having a known structure housed in the lower end portion of the center pillar P, the shoulder belt portion 221 of the seat belt 201 having one end wound around the rotating shaft 209 is drawn upward, and the shoulder at the upper end of the center pillar P is pulled out. It extends obliquely downward along the front face of the upper body of the occupant 10 through the anchor 207, and is folded back by the tongue plate 231 to become the lap belt portion 222 and reach the outer anchor 210 at the lower end of the center pillar P. The tongue plate 231 is coupled to a known buckle 232 standing on the vehicle floor F. FIG. 2 shows a state where the electrodes 71 and 72 are attached to the shoulder belt portion 221.

  In FIG. 3, the detail of the attachment state of the electrodes 71 and 72 to the seatbelt 201 is shown. In the example of FIG. 3, the electrodes 71 and 72 are attached to both the shoulder belt portion 221 and the lap belt portion 222, but the electrode 71 and 72 may be attached to only one of the shoulder belt portion 221 and the lap belt portion 222. The attachment positions of the electrodes 71 and 72 are places where the seat belt 201 and the occupant 10 come into contact. A plurality of sets of electrodes 71 and 72 may be mounted on the seat belt so as to correspond to the occupant's physique. The distance D between the electrode 71 and the electrode 72 is set to a value that maximizes the effect of noise removal in the ground detection circuit 70 (see FIG. 10), for example. The shapes of the electrodes 71 and 72 may be circular or semicircular in addition to the rectangular shape.

  4 shows the seat belt 201 as viewed from above, but the width of the electrodes 71 and 72 may be made smaller than the width of the seat belt 201 as described above. Further, as shown in FIG. 5, the electrodes 71 and 72 may be attached to at least a part of different end portions of the seat belt 201 in the width direction. In this case, the electrodes 71 and 72 may be arranged in a staggered manner (the electrode 72 is indicated by a solid line), or the electrodes 71 and 72 may be arranged so as to face each other (the electrode 72 is indicated by a broken line). Further, as shown in FIG. 6, the electrodes 71 and 72 may be attached to a substantially central portion in the width direction of the seat belt 201. Thus, by making the widths of the electrodes 71 and 72 smaller than the width of the seat belt 201, cables 71a and 72a for connecting the electrodes 71 and 72 and the ground detection circuit 70 (see FIG. 10) (details will be described later). Wiring can be facilitated.

  FIG. 7 shows details of attachment of the electrodes 71 and 72 to the seat belt 201 (cross-sectional view of the seat belt 201). The electrodes 71 and 72 are configured as conductive metal plates or conductive cloth pieces (that is, surface electrodes) in which carbon fibers are interwoven, for example, on the shoulder 10 side of the shoulder belt portion 221 or the lap belt portion 222. Bonded or sewn to the surface. Thereby, the electrodes 71 and 72 can be attached without impairing the strength of the seat belt 201. In addition, since the electrodes are not visible to the outside of the vehicle or from other passengers, the aesthetic appearance of the seat belt and the interior of the vehicle is not impaired.

  Cables 71 a and 72 a that connect the electrodes 71 and 72 and the ground detection circuit 70 are wired inside the seat belt 201. The cables 71a and 72a are connected to a resistor 80 and a resistor 82 (see FIG. 10), respectively. The cables 71a and 72a are made of, for example, carbon fiber, and can sufficiently withstand the force applied when the seat belt 201 is pulled out / wound.

  FIG. 8 shows another example of the details of attachment of the electrodes 71 and 72 to the seat belt 201. The electrodes 71 and 72 are configured as surface electrodes as in the example of FIG. 7, and do not protrude from the surface of the shoulder belt portion 221 or the lap belt portion 222 on the side of the occupant 10 and are flush with the seat belt surface. Bonded or sewn to form. Thereby, it is possible to prevent each detection unit from being caught on the occupant's clothes or the like when the seat belt is pulled out / taken up. In addition, since the electrodes are not visible to the outside of the vehicle or from other passengers, the aesthetic appearance of the seat belt and the interior of the vehicle is not impaired. Of course, in the example of FIGS. 7 and 8, the electrodes 71 and 72 may be arranged on the surface of the seat belt 201 opposite to the occupant 10, that is, so as to cover a part of the seat belt 201.

  In the configuration of FIG. 8, the cross-sectional heights of the electrodes 71 and 72 may be the same as the cross-sectional height of the seat belt 201. FIG. 9 shows an example of the configuration. In this case, the cables 71a and 72a are wired in a direction in which other electrodes are not arranged and connected to the ground detection circuit 70.

  3 to 9 described above, the electrodes 71 and 72 use surface electrodes, and these surface electrodes are bonded or sewn to the seat belt 201. However, instead of the surface electrodes, a conductive material such as carbon fiber is used. It is good also as a structure which weaves a property member in the seatbelt 201. Thereby, the electrodes 71 and 72 and the cables 71a and 72a can be integrally formed (for example, as one thread), the manufacturing cost can be reduced, and there is a concern that this may occur in the configurations of FIGS. The problem of insufficient strength or durability at the joint between the electrodes 71 and 72 and the cables 71a and 72a can be solved. Alternatively, one of the electrodes 71 and 72 may be bonded or sewn to the seat belt 201 using a surface electrode, and the other may be woven into the seat belt 201 with a conductive member.

  Further, the lengths of the electrodes 71 and 72 in the pulling / winding direction of the seat belt 201 are not particularly limited as long as they reliably contact the occupant 10. For example, the electrodes 71 and 72 are arranged in the width direction of the seat belt 201. 5 (see FIG. 5), the length L of the electrodes 71 and 72 in the pulling / winding direction of the seat belt 201 may be the same as the length of the seat belt 201.

  FIG. 10 shows the configuration of the sensor system 28. In addition, this structure is shown in FIG. Since this is the same configuration as that of FIG. The sensor system 28 includes sensors 30 and 40, a differential amplifier 39, a signal processing circuit 60, a ground detection circuit 70, and the like. The sensors 30 and 40 correspond to the bioelectric signal detection unit of the present invention. The signal processing circuit 60 corresponds to the signal processing unit of the present invention. The ground detection circuit 70 corresponds to the noise removal unit of the present invention. In the other drawings, the same reference numerals as those in FIG. 10 are used for the same components as those in FIG.

  In the sensors 30 and 40, the bioelectric signals detected by the electrodes 31 and 41 are amplified by, for example, several times in the amplifiers 33 and 43, and further amplified by, for example, several times in the differential amplifier 39, and the sensor signal ( 55) is output to the signal processing circuit 60.

  This configuration is suitable for detecting, for example, an electrocardiogram signal and myoelectric potential. When an electrocardiogram signal is detected, the electrodes 31 and 41 are disposed on the seat 200 so as to correspond to substantially the left side and the substantially right side of the back of the occupant 10, respectively. Further, when detecting the myoelectric potential, the electrodes 31 and 41 are arranged on the seat 200 so as to be aligned on the same muscle fiber where the myoelectric potential is to be detected, such as the arm, back, and leg of the occupant 10, for example. Further, the number of electrodes to be arranged is not limited to two.

The ground detection circuit 70 amplifies the second ground signal (G2) detected by the electrode 72 by the amplifier 85, thereby removing noise superimposed on the passenger potential and outputting the reference potential signal (75) to the signal processing circuit 60. To do.

  The signal processing circuit 60 performs signal processing based on the reference potential signal (75) and the sensor signal (bioelectric signal: 55), and acquires biosignal information of the occupant 10.

  FIG. 11 shows an outline of the operation of the ground detection circuit 70. The circuits of the sensors 30 and 40 are grounded to the common ground G1, and the ground detection circuit 70 is grounded to the second ground G2 representing the battery ground. In order to measure a biological signal, a measurement reference point is required. As a measurement reference point in the case of a vehicle, the vehicle body (GND in FIGS. 10 and 11) is finally used. As a matter of course, since the occupant 10 and the vehicle body are not completely grounded from the ground, the GND is likely to fluctuate and is easily affected by noise (see the portion (a) in FIG. 11).

Therefore, using the difference between the vehicle ground potential representing the occupant of potential and the battery ground, the noise is removed in the range of ground potential difference between the site and the vehicle body close to the passenger (corresponding to the potential V1 of FIG. 11), the reference potential As a signal , it is possible to obtain the biological signal information by processing the sensor signal while reducing the influence of noise (see the part (b) of FIG. 11). With this function, even when noise enters from the outside, a biological signal from which noise components are eliminated can be measured by being applied to both GNDs.

FIG. 12 shows a detected electrocardiogram signal that is not subjected to noise removal by the configuration of the prior art. FIG. 13 shows an electrocardiogram signal detected by the configuration of the present invention. As shown in FIG. 13, by applying the configuration of the present invention, noise can be removed and a stable electrocardiographic signal close to an actual waveform can be acquired.
Although the embodiments of the present invention have been described above, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the spirit of the claims. Various modifications based on this are possible.

(Reference example)
FIG. 14 shows a configuration example of the pulse wave sensor 300. The pulse wave sensor 300 replaces the sensors 30 and 40 and the differential amplifier 39 of FIG. 11 or is added to the configuration of FIG. The pulse wave sensor 300 includes a light emitting element 301 (light emitting unit of the present invention), a light receiving element 302 (light receiving unit of the present invention), a current / voltage conversion circuit 303, a DC offset removal circuit 304, an amplification circuit 305, and a low pass filter 306. Consists of. The light emitting element 301 and the light receiving element are disposed on the seat 200 so as to be substantially left of the back of the occupant 10, for example, or a grip portion (for example, so-called “10:10”) of the steering handle 250 (see FIG. 1). Position) is located near.

  When light is emitted from the light emitting element 301 toward the occupant 10, a part of the light strikes the blood vessel 10a of the occupant 10 and is absorbed by hemoglobin in the blood flowing through the blood vessel 10a, and the remaining light is reflected by the blood vessel 10a. The light is scattered and part of the light enters the light receiving element 302. Since the amount of hemoglobin in the blood flowing through the blood vessel 10a is waved by the blood pulsation, the light absorbed by the hemoglobin is also waved. As a result, the amount of received light that is reflected by the blood vessel 10a and enters the light receiving element 302 changes.

  In the light receiving element 302, a change in the amount of received light is detected as a change in current. Therefore, this is converted into a voltage in the current / voltage conversion circuit 303, and an offset generated at the time of conversion is removed by the DC offset removal circuit 304 for amplification. A circuit 305 amplifies the voltage to a predetermined voltage level. In the low-pass filter 306, the CR low-pass filter 306a removes noise from the signal from the amplifier circuit 305. The low-pass filter 306 includes a differential amplifier 306 b, and the gain of the differential amplifier 306 b is adjusted so as to be a voltage that can be input to the signal processing circuit 60.

DESCRIPTION OF SYMBOLS 1 Biological sensing apparatus for vehicles 10 Occupant 28 Sensor system 30, 40 Sensor (bioelectric signal detection part)
39 Differential Amplifier 60 Signal Processing Circuit (Signal Processing Unit)
70 Ground detection circuit (noise removal unit)
71 electrode (first ground signal detector)
72 electrodes (second ground signal detector)
201 seat belt 221 shoulder belt portion 222 lap belt portion 300 pulse wave sensor 301 light emitting element (light emitting portion)
302 Light receiving element (light receiving part)

Claims (6)

A bioelectric signal detector (31, 41) for detecting a bioelectric signal of an occupant seated in a vehicle seat;
An occupant potential detector (72) for detecting the occupant potential ;
A vehicle ground potential electrode (71) grounded to the vehicle ground potential via a cable ;
Using a potential difference between the occupant potential and the ground potential of the vehicle, a noise removing unit that removes noise superimposed on the occupant potential and outputs a reference potential signal ;
By the reference potential signal, it performs signal processing with respect to the living body electric signal, a signal processing unit that acquires the occupant of biological information,
With
The occupant potential detection unit and the vehicle ground potential electrode are attached to a seat belt provided in the seat at a place where the seat belt and the occupant come into contact with each other at a predetermined interval. Biological sensing device for vehicles. The biological sensing device for a vehicle according to claim 1, wherein the occupant potential detection unit and the vehicle ground potential electrode are attached to a lap belt portion of the seat belt at a predetermined interval . The living body sensing device for vehicles according to claim 1 or 2 with which said crew member potential detection part and said vehicle ground potential electrode are constituted as a surface electrode attached to said seat belt, respectively. The living body sensing device for a vehicle according to claim 1 or 2, wherein the occupant potential detection unit and the vehicle ground potential electrode are each configured as a conductive member woven into at least a part of the seat belt. The bioelectric signal detecting unit is mounted on a seat of said vehicle, comprising a plurality of electrodes for detecting the potential signal emanating from the occupant of each unit seated on said seat,
The vehicular sensing device according to any one of claims 1 to 4, wherein the bioelectric signal of the occupant is detected by amplifying a difference signal between potential signals detected by the electrodes. The vehicular electrical sensing device according to claim 5, wherein the bioelectric signal detection unit is disposed on the seat so as to correspond to a left side and a right side of the back of the occupant .