JP7238630B2 - Biometric information detection system - Google Patents

Description

The present invention relates to a biological information detection system.

2. Description of the Related Art Conventionally, a biometric information detection system in which a transmitting antenna and a receiving antenna are arranged is known. In this system, a receiving antenna receives radio waves that are transmitted from a transmitting antenna and pass through a person. Then, the heartbeat is calculated based on the received signal corresponding to the radio waves received by the receiving antenna.

JP 2016-174870 A

However, in the technology using the transmitting antenna and the receiving antenna as described above, noise is more likely to occur than when calculating the heart rate with a sensor attached to a person, and as a result, the heart rate cannot be calculated with high accuracy. becomes difficult. This applies not only to heartbeats, but also to general biological information such as respiration and pulse.

In view of the above points, the present invention is a technique for calculating biological information based on a received signal corresponding to the received radio wave when the receiving antenna receives a radio wave transmitted from a transmitting antenna and transmitted or reflected by a person, An object of the present invention is to calculate biometric information with higher accuracy than before.

In order to achieve the above object, the invention according to claim 1 has a plurality of receiving antennas (13a, 13b, 13c) arranged at mutually different positions for receiving radio waves, and a transmitting antenna (12) from which radio waves are radiated. an acquisition unit (110) for acquiring a plurality of received signals (P1, P2, P3) corresponding to the radio waves received by the plurality of receiving antennas, and the signals radiated from the transmitting antennas and reflected or transmitted through the human body. A selection unit (150) for selecting, from the plurality of reception antennas, a specific antenna corresponding to a received signal in which the ratio of the biological signal corresponding to the radio wave to noise other than the biological signal is greater than a reference value, and the selection unit selects a calculation unit (240) for calculating the biological information of the person based on a received signal corresponding to the radio wave received by the specific antenna , wherein the transmitting antenna and the plurality of receiving antennas are mounted on a vehicle, The selection unit selects the specific antenna based on the plurality of received signals corresponding to the radio waves received by the plurality of reception antennas when the vehicle is stopped, and the calculation unit selects the specific antenna when the vehicle is running. The biometric information detection system calculates the biometric information based on a received signal corresponding to radio waves received by the specific antenna when the device is in motion .
Further, the invention according to claim 6 provides a plurality of receiving antennas (13a, 13b, 13c) arranged at mutually different positions for receiving radio waves, and when radio waves are radiated from the transmitting antenna (12), the plurality of receiving antennas (13a, 13b, 13c) an acquisition unit (110) for acquiring a plurality of received signals (P1, P2, P3) corresponding to the radio waves received by the receiving antenna of the above; A selection unit (150) for selecting, from the plurality of reception antennas, a specific antenna corresponding to a received signal in which the ratio of the biological signal to noise other than the biological signal is greater than a reference value, and a specific antenna selected by the selection unit receive a calculation unit (240) for calculating the biometric information of the person based on the received signal corresponding to the radio wave received, the calculation unit being not selected by the selection unit from among the plurality of receiving antennas. Based on the received signal corresponding to the radio wave received by the noise removal antenna, noise is removed from the received signal corresponding to the radio wave received by the specific antenna, and the biological information is calculated based on the received signal after removal. The amount of noise removed from the received signal corresponding to the radio wave received by the specific antenna increases as the received signal corresponding to the radio wave received by the noise removing antenna becomes stronger, and the noise removing antenna is equal to the specific antenna It is a biological information detection system that becomes smaller as it is farther from the body.
Further, according to the eighth aspect of the present invention, when radio waves are radiated from a plurality of receiving antennas (13a, 13b, 13c) arranged at mutually different positions to receive radio waves, and the transmitting antenna (12), the plurality of receiving antennas (13a, 13b, 13c) an acquisition unit (110) for acquiring a plurality of received signals (P1, P2, P3) corresponding to the radio waves received by the receiving antenna of the above; A selection unit (150) for selecting, from the plurality of reception antennas, a specific antenna corresponding to a received signal in which the ratio of the biological signal to noise other than the biological signal is greater than a reference value, and a specific antenna selected by the selection unit receive a calculation unit (240) for calculating the biometric information of the person based on the received signal corresponding to the radio waves received, the transmitting antenna and the plurality of receiving antennas being mounted on a vehicle; Comparing the first seat (3) and the second seat (3z), the plurality of receiving antennas are closer to the first seat (3), and the biometric information sensing system The other receiving antennas (13az, 13bz, 13cz) are closer to the second seat than the seat, and the calculating unit determines that the person is seated on the first seat, and the second seat noise is removed from the received signal corresponding to the radio wave received by the specific antenna, based on the received signal corresponding to the radio wave received by the other receiving antenna, and the reception after removal The biological information detection system calculates the biological information based on the signal.

In this manner, a specific antenna corresponding to a received signal having a ratio of the biosignal to noise greater than the reference value is selected from a plurality of receiving antennas, and biometric information is calculated based on the received signal corresponding to the radio wave received by the specific antenna. be. Therefore, the biological information can be calculated by selectively using the receiving antenna receiving less noise from among the plurality of receiving antennas, so that the biological information can be calculated with higher accuracy than otherwise.

It should be noted that the reference numerals in parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and specific components etc. described in the embodiments described later.

1 is a configuration diagram of a biological information detection system according to a first embodiment; FIG. It is a flowchart of the process which a process part performs at the time of a stop. 4 is a flowchart of processing executed by a processing unit when the vehicle is running; FIG. 4 is a schematic diagram showing a procedure for selecting specific antennas and antennas to be removed; FIG. 4 is a schematic diagram showing a procedure for removing noise from frequency characteristics F1 based on frequency characteristics F2; It is a flow chart of processing which a treating part performs at the time of a stop in a 2nd embodiment. FIG. 10 is a flowchart of processing executed by a processing unit when the vehicle is running in the third embodiment; FIG. It is a weight calculation table. It is a block diagram of the biometric information detection system in 4th Embodiment. It is a flowchart of the process which a process part performs at the time of a stop.

(First embodiment)
The first embodiment will be described below. As shown in FIG. 1, the biological information detection system according to the present embodiment is mounted on a vehicle and calculates and outputs the heart rate of a person 2 sitting on a seat 3 serving as a driver's seat of the vehicle as biological information. The biometric information of the person 2 refers to information related to the bioactivity of the person 2 . This biological information detection system includes a biological information detection device 4 , a transmitter 11 , a transmission antenna 12 , a first reception antenna 13 a , a second reception antenna 13 b , a third reception antenna 13 c and a receiver 14 .

In this embodiment, radio waves are transmitted from the transmission antenna 12 when the vehicle is stopped. At that time, based on the three reception signals corresponding to the radio waves received by the first reception antenna 13a, the second reception antenna 13b, and the third reception antenna 13c, the biological information detection device 4 mainly detects the heart rate of the person 2. A receiving antenna that receives radio waves containing a signal is selected as a specific antenna. Furthermore, the biological information detection device 4 selects a receiving antenna that receives radio waves that mainly contain noise as a noise removal antenna. When the vehicle is running, the biological information detection device 4 uses the received signal received by the noise elimination antenna to eliminate noise from the received signal corresponding to the radio wave received by the specific antenna. Then, the biological information detection device 4 calculates and outputs the heart rate of the person 2 based on the noise-removed received signal. The heart rate can be calculated more accurately by selecting such a specific antenna and noise elimination antenna. The details of the constituent elements of this biological information detection system will be described below.

The transmitter 11 outputs a transmission signal of a predetermined frequency (for example, a frequency of 900 MHz band) to the transmission antenna 12 . The transmitting antenna 12 is arranged on the front side of the vehicle traveling direction with respect to the seat 3 in the instrument panel in the vehicle compartment. The transmission antenna 12 transmits a radio signal corresponding to the transmission signal from the transmitter 11 toward the upper half of the body of the person 2 seated on the seat 3 .

The first receiving antenna 13a, the second receiving antenna 13b, and the third receiving antenna 13c are arranged to face the transmitting antenna 12 with the person 2 interposed therebetween. Specifically, the receiving antennas 13a, 13b, and 13c are arranged at different positions in the vehicle width direction. The receiving antennas 13a, 13b, and 13c are configured to receive radio signals transmitted from the transmitting antenna 12, respectively.

For example, the receiving antennas 13a, 13b, 13c may be embedded in the seat back 3a of the vehicle as shown in FIG. Since the receiving antennas 13 a , 13 b , 13 c are attached to the seat 3 in this way, the receiving antennas 13 a , 13 b , 13 c can be easily attached to positions close to the person 2 sitting on the seat 3 . Seat 3 corresponds to a specific seat.

The receiver 14 amplifies and outputs the radio signals received by the receiving antennas 13a, 13b, and 13c. Specifically, the receiver 14 amplifies the radio wave signal received by the first receiving antenna 13a and outputs it to the biological information detection device 4 as a received signal P1. Further, the receiver 14 amplifies the radio wave signal received by the second receiving antenna 13b and outputs it to the biological information detecting device 4 as a received signal P2. Further, the receiver 14 amplifies the radio wave signal received by the third receiving antenna 13c and outputs it to the biological information detecting device 4 as a received signal P3.

The biological information detection device 4 includes an input section 41 , a storage section 42 , an output section 43 and a processing section 44 . The input unit 41 converts received signals P 1 , P 2 , and P 3 , which are analog signals input from the receiver 14 , into digital signals and outputs the digital signals to the processing unit 44 . The storage unit 42 includes RAM, ROM, writable nonvolatile storage media, and the like. RAM, ROM, and writable non-volatile storage media are all non-transitional physical storage media. The output unit 43 outputs the signal input from the processing unit 44 to a device external to the biological information detection device 4 . The external device of the output destination may be, for example, an in-vehicle navigation device that performs route guidance, an in-vehicle data communication module that communicates with the outside of the vehicle, or a mobile communication terminal that the person 2 carries.

The processing unit 44 is a device that executes processing according to a program recorded in the ROM of the storage unit 42 or a writable nonvolatile storage medium, and uses the RAM of the storage unit 42 as a work area during execution. do.

The operation of the biological information detection system configured as described above will be described below. Transmitter 11 outputs a transmission signal of a predetermined frequency to transmission antenna 12 . Then, the transmitting antenna 12 radiates a radio wave signal corresponding to the transmission signal from the transmitter 11 toward the driver's seat and the person 2 .

Some of the radio signals emitted from the transmitting antenna 12 pass through the body of the person 2 and are received by at least one of the receiving antennas 13a, 13b, 13c. The body of the person 2 functions as a dielectric with respect to radio signals. Therefore, when the radio signal passes through the body of the person 2, dielectric loss occurs in the electric field strength of the radio signal. The shape of the heart 2a changes as it expands and contracts. For this reason, in the radio wave signal transmitted through the heart 2a shown in FIG. .

Therefore, the intensity of the radio signal received by any one of the receiving antennas 13a, 13b, and 13c includes a component that changes in synchronization with the heartbeat of the heart 2a. Therefore, by receiving the radio signal, the level of the received signal output from the receiver 14 based on the electrical signal from any one of the receiving antennas 13a, 13b, and 13c is synchronized with the heartbeat of the heart 2a. It contains many biological signals, which are components that fluctuate over time.

On the other hand, among the radio signals from the transmitting antenna 12, the radio signals that do not pass through the body of the person 2 are transferred to the receiving antennas 13a and 13b as diffracted waves traveling around the person, reflected waves reflected by objects other than the person inside the vehicle, and the like. , 13c as radio signals. These diffracted waves and reflected waves mainly contain components unrelated to the heartbeat of the person 2, that is, noise.

Among the receiving antennas 13a, 13b, and 13c, the received signal output from the receiver 14 in response to the electrical signal from the antenna that received the radio wave, the diffracted wave, and the reflected wave transmitted through the heart 2a includes noise components and the heartbeat. components are also included. On the other hand, the received signal output from the receiver 14 in response to the electrical signal from the antenna which received the diffracted wave and the reflected wave but hardly received the radio wave transmitted through the heart 2a contains almost only noise components. is.

Thus, when a plurality of receiving antennas 13a, 13b, and 13c are arranged at different positions, one receiving antenna receives radio waves on which biosignals are superimposed, and another receiving antenna receives radio waves on which biosignals are hardly superimposed. often receive. On the other hand, the amount of noise in the radio waves received by the receiving antennas 13a, 13b, and 13c is often the same.

When radio signals are received in this way, the receiving antennas 13a, 13b, and 13c each output an electric signal whose signal strength changes according to the electric field strength of the received radio signal. The receiver 14 amplifies these electrical signals and outputs received signals P1, P2, and P3 corresponding to the electrical signals from the receiving antennas 13a, 13b, and 13c to the biological information detecting device 4, respectively.

The transmitter 11, the transmitting antenna 12, the receiving antennas 13a, 13b, 13c, and the receiver 14 operate as described above both when the vehicle is not running and when the vehicle is running. By continuously operating the transmitter 11, the transmitting antenna 12, the receiving antennas 13a, 13b, 13c, and the receiver 14 as described above, the signal strength of the input unit 41 of the biological information detection device 4 increases over time. are continuously input. One of the received signals P1, P2, and P3 includes a biosignal representing a heart rate, which is biometric information. Each of the received signals P1, P2, and P3 contains noise unrelated to biological information.

As described above, the input unit 41 outputs to the processing unit 44 digital signals having values corresponding to the signal strengths of the received signals P1, P2, and P3 that have been input. Therefore, the processing unit 44 receives information on changes in intensity of the received signals P1, P2, and P3 over time. The information about intensity changes of the received signals P1, P2, and P3 over time is a time waveform, that is, a waveform in the time domain. More specifically, this time waveform contains signal strength information at each of a plurality of discrete sampling timings spaced at predetermined time intervals.

The processing unit 44 executes the processes shown in FIGS. 2 and 3 by reading and executing a predetermined program from the ROM of the storage unit 42 or a writable non-volatile storage medium. For example, the processing unit 44 executes the processing of FIG. The processing shown in FIG. 3 is executed until

The processing unit 44 can determine whether or not the vehicle is running based on the output of a vehicle speed sensor (not shown), for example. Turning on and off the main power source of the vehicle corresponds to turning on and off the ignition switch if the vehicle has an internal combustion engine that generates power for running. In addition, if the vehicle does not have an internal combustion engine but has an electric motor that is driven by electric power to generate power for running, the main control permits energization of the motor in response to depression of the accelerator pedal. Turning the switch on and off corresponds to turning on and off the main power source of the vehicle.

Alternatively, when the main power source of the vehicle is on, the processing unit 44 performs the processing of FIG. 2 each time the vehicle stops due to waiting for a signal or the like, and performs the processing of FIG. 3 when the vehicle is running. It can be like this.

First, the processing of FIG. 2 will be described. In the process of FIG. 2, the processing unit 44 first executes a loop process starting from step 110 and ending at step 140 or step 150 for each of the receiving antennas 13a, 13b, and 13c. That is, loop processing is executed for the number of receiving antennas 13a, 13b, and 13c.

In each loop process, in step 110, the processing unit 44 converts the time waveform of the latest received signal (for example, the received signal P1) corresponding to the radio waves received by the target receiving antenna (for example, the first receiving antenna 13a) to a predetermined Extract a time interval of length. For example, only the time interval from 1 second before to the current time is extracted.

Subsequently, in step 120, the processing unit 44 performs a discrete Fourier transform on the time waveform extracted in the immediately preceding step 110, thereby obtaining frequency characteristics indicating the relationship between the frequency and intensity of the received signal in the time interval. A frequency response is a waveform in the frequency domain. This frequency characteristic is data in which an intensity value is assigned to each of a plurality of frequency bins within a predetermined frequency interval.

Subsequently, in step 130, the SN ratio of the target received signal is calculated based on the frequency characteristics obtained in step 120 immediately before. Here, the SN ratio of the received signal is the ratio of the biological signal contained in the received signal to the noise.

This SN ratio is calculated by the processing unit 44 as follows. First, the frequency bin with the highest intensity is identified in the target frequency characteristic. Then, let the signal strength S be the strength in the frequency bin. Then, let noise intensity N be the sum of intensities in all frequency bins other than the frequency bin in question. A value obtained by dividing the signal strength S by the noise strength N is defined as the SN ratio. The reason why the SN ratio is calculated in this way is that if the received signal of interest mainly contains the biological signal derived from the heartbeat, then the signal strength S is the strength of the biological signal itself, and the noise strength N is the strength of the biological signal itself. This is because there is a high possibility that what is obtained is the intensity of the noise itself. When the vehicle is stopped, the receiving antenna that receives the radio wave on which the biological signal derived from the heartbeat is superimposed hardly receives noise. This is because the vibration of the vehicle is small and the movement of the body of the person 2 due to the vibration is also small when the vehicle is stopped without traveling.

Alternatively, this SN ratio may be calculated by the processing unit 44 as follows. First, a group of consecutive frequency bins including frequency bins with the highest intensity in the frequency characteristic of interest is identified. For example, identify the frequency bin with the highest intensity and its adjacent frequency bins. Then, let signal strength S be the total sum of strengths in the specified frequency bin group. Then, let noise intensity N be the sum of intensities in all frequency bins other than the identified frequency bin group. A value obtained by dividing the signal strength S by the noise strength N is defined as the SN ratio. Note that the frequency width indicated by the continuous frequency bin group including the frequency bin with the highest intensity becomes narrower as the time interval explained in step 110 becomes longer.

Subsequently, in step 140, it is determined whether or not the SN ratio calculated in the previous step 130 is larger than the reference value ε. exit.

This reference value ε is set as an index for determining whether or not the receiving antenna of interest is receiving radio waves on which biosignals derived from heartbeats are mainly superimposed. If the target receiving antenna receives radio waves on which biosignals derived from heartbeats are mainly superimposed, the SN ratio becomes very large. On the other hand, if the target receiving antenna receives radio waves on which noise is mainly superimposed, the SN ratio becomes very small.

For example, as shown in FIG. 4, the third receiving antenna 13c receives a radio wave on which a biosignal derived from heartbeat is mainly superimposed, and the radio wave on which a biosignal derived from heartbeat and noise are superimposed is received by the second receiving antenna. 13b received. Assume that the first receiving antenna 13a receives radio waves on which only noise is superimposed.

In this case, as shown in FIG. 4, the frequency characteristic of the reception signal P3 corresponding to the radio wave received by the third reception antenna 13c rises sharper and larger than other noises in the frequency bin corresponding to the heartbeat. Therefore, in the loop processing for the third receiving antenna 13c, it is determined at step 140 that the SN ratio is greater than the reference value ε, and as a result, the processing proceeds to step 150. FIG.

In this case, as shown in FIG. 4, the frequency characteristics of the reception signals P1 and P2 corresponding to the radio waves received by the first and second reception antennas 13a and 13b are such that the rise in the frequency bin corresponding to the heartbeat is It is on the same level as noise or slightly larger. Therefore, in the loop processing for the first and second receiving antennas 13a and 13b, it is determined in step 140 that the SN ratio is equal to or less than the reference value ε, and as a result, the current loop processing ends.

At step 150, the processing unit 44 selects the target antenna as a specific antenna for biometric information estimation. In the case of FIG. 4, in the process after step 110 targeting the third receiving antenna 13c, in step 150, the third receiving antenna 13c is selected as the specific antenna. After step 150, the current loop processing ends.

When the loop processing for all of the receiving antennas 13a, 13b, and 13c is completed, the processing proceeds to step 160. FIG. In step 160, the processing unit 44 selects, from among the receiving antennas not selected as specific antennas in the above three loop processes, the noise eliminating antenna corresponding to the received signal containing the least amount of biological signals derived from heartbeats. to elect. For example, among the receiving antennas not selected as the specific antenna, the receiving antenna with the smallest SN ratio of the corresponding received signal is selected as the noise elimination antenna. Therefore, in the case of FIG. 4, the first receiving antenna 13a is selected as the noise elimination antenna. After step 160, the process of FIG. 2 ends.

In the case of FIG. 4, in the processing of FIG. 2, the third receiving antenna 13c is the only receiving antenna for which the SN ratio of the received signal is greater than or equal to the reference value ε. However, in some cases, there may be a plurality of receiving antennas with the SN ratio of the received signal equal to or greater than the reference value ε. In such a case, only one of the plurality of receiving antennas may be selected as the specific antenna. For example, among the plurality of receiving antennas, the receiving antenna with the highest SN ratio of the received signal may be selected as the specific antenna.

Next, the processing of FIG. 3 will be described. As described above, the processing unit 44 repeatedly executes the processing of FIG. 3 (periodically, for example, every one minute) while the vehicle is running.

In the process of FIG. 3, the processing unit 44 first executes a loop process starting from step 210 and ending at step 220 for each of the receiving antennas 13a, 13b, and 13c. That is, loop processing is executed for the number of receiving antennas 13a, 13b, and 13c.

In each loop process, first, in step 210, the processing unit 44 extracts the time waveform of the latest received signal corresponding to the radio waves received by the target receiving antenna for a time segment of a predetermined length. For example, only the time interval from 1 second before to the current time is extracted.

Subsequently, in step 220, the processing unit 44 performs a discrete Fourier transform on the time waveform extracted in the immediately preceding step 210, thereby obtaining frequency characteristics indicating the relationship between the frequency and intensity of the received signal in the time interval. This frequency characteristic is data in which an intensity value is assigned to each of a plurality of frequency bins within a predetermined frequency interval. After step 220, the current loop processing ends.

When the loop processing for all of the receiving antennas 13a, 13b, and 13c is completed, the processing proceeds to step 230. FIG. In step 230, the processing unit 44 performs processing using the frequency characteristics specified in step 220 of the loop processing for the specific antenna and the frequency characteristics specified in step 220 of the loop processing for the noise elimination antenna. I do. Hereinafter, the former frequency characteristic will be referred to as the frequency characteristic of the specific antenna, and the latter frequency characteristic will be referred to as the frequency characteristic of the noise elimination antenna. The specific antenna and noise elimination antenna used here may be the specific antenna and noise elimination antenna selected in the last process of FIG. 2, or the specific antenna and noise elimination antenna selected at other timings It may be a noise elimination antenna.

Specifically, in step 230, the processing unit 44 removes noise from the frequency characteristics of the specific antenna based on the frequency characteristics of the noise removal antenna. More specifically, as shown in FIG. 5, the frequency characteristic F2 of the noise elimination antenna is subtracted from the frequency characteristic F1 of the specific antenna. Subtraction is intensity subtraction between the same frequency bins.

Basically, the frequency characteristic F1 of the specific antenna contains a heartbeat-derived biological signal and noise, and the frequency characteristic F2 of the noise elimination antenna contains almost only noise. Therefore, by performing the subtraction as described above, the resulting frequency characteristic F3=F1-F2 has almost all of the noise removed and the heartbeat-derived biosignal remains, as shown in FIG.

Thus, the larger the frequency characteristic F2, the greater the amount of noise removed from the frequency characteristic F1. That is, the amount of noise removed from the received signal corresponding to the radio wave received by the specific antenna increases as the received signal corresponding to the radio wave received by the noise elimination antenna becomes stronger.

Subsequently, in step 240, the heart rate of person 2 is calculated from the frequency characteristic F3 of the subtraction result obtained in step 230. FIG. Specifically, the heart rate is calculated in units of bpm by multiplying the number expressed in units of hertz of the frequency with the highest intensity in the frequency characteristic F3 by 60. FIG. bpm is an abbreviation for beat per minute, and is a unit equal to 1 in the case of one heart beat per minute.

When the vehicle is running, there is a lot of noise due to vibrations of the vehicle, etc. Therefore, it may be difficult to accurately calculate the heart rate simply by using the frequency characteristics of the specific antenna. However, as described above, by using the frequency characteristics of the specific antenna after removing the noise, the possibility of correctly calculating the heart rate increases.

Subsequently, in step 250, the heart rate calculated in step 240 immediately before is output to the output unit 43 as digital data. The output unit 43 outputs the digital data of the heart rate input from the processing unit 44 in this manner to a device external to the biological information detection device 4 . After step 250, the process of FIG. 3 ends.

As described above, the processing unit 44 selects, from the receiving antennas 13a, 13b, and 13c, specific antennas corresponding to the received signals with the SN ratios of the received signals P1, P2, and P3 larger than the reference value. Then, the processing unit 44 calculates the heart rate as the biological information of the person 2 based on the received signal corresponding to the radio waves received by the specific antenna.

Therefore, the heart rate can be calculated by selectively using the receiving antenna receiving less noise among the receiving antennas 13a, 13b, and 13c, so that the heart rate can be calculated with higher accuracy than otherwise. .

Being able to selectively use the receiving antenna receiving less noise means that the particular receiving antenna among the receiving antennas 13a, 13b, and 13c is changed. For example, when an occupant sitting on the seat 3 changes from one person to another, there are cases where the receiving antenna serving as the specific antenna changes due to differences in physique and heart position.

Further, for example, even if the occupant sitting on the seat 3 does not change, the receiving antenna serving as the specific antenna may change according to changes in the position of the seat 3 and the reclining angle of the seat back 3a.

Further, for example, even if there is no change in the occupant sitting on the seat 3, the reception antenna serving as the specific antenna may change according to the change in the way the occupant sits on the seat 3. Further, for example, even if there is no change in the occupant sitting in the seat 3, if there is a change in the seating situation in another seat, the receiving antenna serving as the specific antenna may change. Therefore, the receiving antenna serving as the specific antenna may or may not change during the period from when the main power source of the vehicle is turned on until it is turned off.

Such changes are the same for noise rejection antennas. In other words, by being able to flexibly select the specific antenna and the noise elimination antenna according to the situation, the heart rate can be calculated with high accuracy in a wide range of situations compared to the case where the specific antenna and the noise elimination antenna are fixed. .

The processing unit 44 also calculates the SN ratio based on the frequency characteristics of the received signals P1, P2 and P3. By using the frequency characteristic in this way, the ratio of the biological signal in the received signal to the noise can be stably calculated. This is because biosignals such as heartbeats have generally stable frequencies. Similarly, by using the frequency characteristic, it is possible to easily distinguish which component is the biological signal and which component is the noise, so that the SN ratio can be easily calculated.

Further, the processing unit 44 selects the specific antenna and the noise elimination antenna based on the reception signals P1, P2 and P3 corresponding to the radio waves received by the reception antennas 13a, 13b and 13c when the vehicle is stopped. Then, the processing unit 44 converts the received signals P1, P2, and P3 according to the radio waves received by the receiving antennas 13a, 13b, and 13c while the vehicle is running, using such specific antennas and noise elimination antennas. Based on this, heart rate is calculated.

When the vehicle is stopped, noise is less likely to appear in the received signal than when the vehicle is running. Therefore, it becomes easier to correctly select a specific antenna at this time. By using the specific antennas selected in this manner while the vehicle is running, biometric information can be calculated with high accuracy even while the vehicle is running.

Further, the processing unit 44 removes noise from the received signal corresponding to the radio wave received by the specific antenna based on the received signal corresponding to the radio wave received by the noise elimination antenna that has not been selected as the specific antenna.

Received signals corresponding to radio waves received by the noise elimination antenna tend to be mainly noise. This is because when multiple receiving antennas are placed at different positions, one receiving antenna often receives radio waves with biosignals superimposed thereon, and another receiving antenna receives radio waves with little biosignal superimposed thereon. is. However, in many cases, the received signal corresponding to the radio wave received by the noise elimination antenna and the received signal corresponding to the radio wave received by the specific antenna contain approximately the same amount of noise. Therefore, by removing noise from the received signal corresponding to the radio wave received by the specific antenna based on the received signal corresponding to the radio wave received by the noise elimination antenna and calculating the biological information based on the received signal after removal, Biometric information can be calculated with higher accuracy.

In this embodiment, the processing unit 44 functions as an acquisition unit by executing step 110 in FIG. 2 and functions as a selection unit by executing step 150 . It also functions as a calculator by executing step 240 in FIG.

(Second embodiment)
Next, a second embodiment will be described. In this embodiment, the processing contents of the processing unit 44 are partially changed from those of the first embodiment. Specifically, the processing unit 44 of the present embodiment executes the processing in FIG. 6 instead of the processing in FIG. The process of FIG. 6 has the process of step 115 added to the process of FIG. Other configurations and processes are the same as those of the first embodiment.

After acquiring the time waveform of the received signal in step 110 in the processing of FIG. At step 115, it is determined whether or not the variation gradient is greater than a predetermined reference value σ. The variation gradient is the variation gradient of the strength of the time waveform (that is, the reception level) acquired in step 110 immediately before.

For example, the variation slope can be the absolute value of the difference between the maximum and minimum intensity values in the current time interval, or the absolute value of the difference between the maximum and minimum intensity values in the current and previous time intervals. There may be. The reference value σ is set, for example, so that the variation gradient of the temporal waveform generated by contraction and expansion of human heartbeat is smaller than the reference value σ.

If the variation gradient is greater than the predetermined reference value σ, the processing unit 44 proceeds to step 120, and if it is equal to or less than the reference value σ, the processing of FIG. 6 is executed again from the beginning. Before executing the processing of FIG. 6 from the beginning, the selection of the specific antenna performed in the processing of FIG. 6 this time is discarded. By doing so, the processing unit 44 selects when the variation gradient is smaller than the reference value σ for all of the receiving antennas 13a, 13b, and 13c, and selects the specific antenna based on the received signal acquired at that time. can be picked out.

For example, even if the vehicle is stopped, the received signal will change significantly when the human body is moving significantly. When there is a large change in the received signal, it is difficult to accurately calculate the SN ratio. Therefore, the SN ratio can be calculated more accurately by selecting a specific antenna by selecting a case where the variation gradients of a plurality of received signals are equal to or less than the reference value σ.

Also, in this embodiment, the same effects can be obtained from the same configuration and operation as those of the first embodiment.

In this embodiment, the processing unit 44 functions as an acquisition unit by executing step 110 in FIG. 6 and functions as a selection unit by executing step 150 . It also functions as a calculator by executing step 240 in FIG.

(Third embodiment)
Next, a third embodiment will be described. In this embodiment, the processing contents of the processing unit 44 are partially changed with respect to the first and second embodiments. Specifically, the processing unit 44 of the present embodiment executes the processing of FIG. 7 instead of the processing of FIG. In the process of FIG. 7, the process of step 225 is added to the process of FIG. 3, and the contents of the process of step 230 are changed. Other configurations and processes are the same as those of the first and second embodiments.

In the processing of FIG. 7, the processing unit 44 proceeds to step 225 when the loop processing for all of the receiving antennas 13a, 13b, and 13c is completed. At step 225, the weight β is calculated. The weight β is a coefficient used when removing noise from a specific antenna, as will be described later. The weight β is calculated using a weight calculation table as shown in FIG. 8 based on the combination of the specific antenna and the noise elimination antenna selected in the process of FIG. 2 or 3 .

In this weight calculation table, a value of weight β is assigned to each combination of a specific antenna and a noise elimination antenna. The values in the weight calculation table are determined in advance by experiments or the like. The numerical value of the weight β shown in FIG. 8 is an example, and is not limited to this. Note that the value of the weight β may be constant regardless of the frequency, as in the example of FIG. 8, or may be an amount that varies according to the frequency (that is, a function of the frequency).

In the example of FIG. 8, the value of the weight β differs depending on the combination of the specific antenna and the noise elimination antenna. This difference is due to the positions of the receiving antennas 13a, 13b, and 13c. The amount of noise included in the received signal corresponding to the radio wave received by the specific antenna and the amount of noise included in the received signal corresponding to the radio wave received by the noise eliminating antenna are often not the same. Then, the difference between the amount of noise included in the received signal corresponding to the radio wave received by the specific antenna and the amount of noise included in the received signal corresponding to the radio wave received by the noise elimination antenna is the difference between the specific antenna and the noise elimination antenna. It changes according to the positional relationship of

For example, if the specific antenna and the noise elimination antenna are located very close to each other, they will receive approximately the same noise in the radio waves. Conversely, the longer the distance between the specific antenna and the noise elimination antenna, the greater the difference in the amount of noise contained in the received signal corresponding to the radio wave received by the noise elimination antenna.

In the example of FIG. 8 as well, when the specific antenna is the first receiving antenna 13a, the weight β is smaller when the noise removing antenna is the third receiving antenna 13c than when the noise eliminating antenna is the second receiving antenna 13b. Further, when the specific antenna is the third receiving antenna 13c, the weight β is smaller when the noise removing antenna is the first receiving antenna 13a than when the noise eliminating antenna is the second receiving antenna 13b. This is because the positional relationship of the receiving antennas 13a, 13b and 13c is shown in FIG. That is, the third receiving antenna 13c is farther from the first receiving antenna 13a than the second receiving antenna 13b, and the first receiving antenna 13a is farther from the third receiving antenna 13c than the second receiving antenna 13b.

In the example of FIG. 8, when the specific antenna is the second receiving antenna 13b, the weight β is smaller when the noise removing antenna is the third receiving antenna 13c than when the noise removing antenna is the first receiving antenna 13a. The distance from the second receiving antenna 13b to the first receiving antenna 13a is substantially the same as the distance from the second receiving antenna 13b to the third receiving antenna 13c. However, the direction from the second receiving antenna 13b to the first receiving antenna 13a is completely different from the direction from the second receiving antenna 13b to the third receiving antenna 13c. This difference results in a difference in the propagation path of radio waves, and as a result, a difference in weight β as described above appears.

Following step 225, the processing unit 44 removes noise from the frequency characteristic of the specific antenna at step 230 based on the frequency characteristic of the noise-removing antenna and the weight β.

Specifically, the amount obtained by multiplying the frequency characteristic F2 of the noise elimination antenna by the weight β is subtracted from the frequency characteristic F1 of the specific antenna. Multiplication and subtraction are intensity operations between the same frequency bins. Therefore, by performing the subtraction as described above, in the resulting frequency characteristic F3=F1−β×F2, as shown in FIG. .

Thus, the larger the frequency characteristic F2 and the weight β, the greater the amount of noise removed from the frequency characteristic F1. That is, the amount of noise removed from the received signal corresponding to the radio wave received by the specific antenna increases as the received signal corresponding to the radio wave received by the noise elimination antenna becomes stronger. The amount of noise removed from the received signal corresponding to the radio wave received by the specific antenna differs depending on the position of the specific antenna and the position of the noise removing antenna, depending on the specific antenna. In this way, the amount of noise to be removed varies according to the position of the noise removing antenna, thereby performing more accurate noise removal.

Also, in this embodiment, the same effects can be obtained from the same configuration and operation as those of the first and second embodiments.

In this embodiment, the processing unit 44 functions as an acquisition unit by executing step 110 in FIG. 2 or FIG. 6 and functions as a selection unit by executing step 150 . Moreover, it functions as a calculation part by performing step 240 of FIG.

(Fourth embodiment)
Next, a fourth embodiment will be described. This embodiment is different in configuration and operation from the first embodiment. Specifically, in addition to the configuration of the first embodiment, the biological information detection system of the present embodiment includes a transmitter 11z, a transmission antenna 12z, a first reception antenna 13az, and a second reception antenna 13bz, as shown in FIG. , a third receiving antenna 13cz, and a receiver 14z.

The configuration of transmitter 11z, transmitting antenna 12z, receiving antennas 13az, 13bz, 13cz, and receiver 14z and the relationship therebetween will be and the relation between them. However, the transmitter 11z, the transmitting antenna 12z, the receiving antennas 13az, 13bz, 13cz, and the receiver 14z are configured to detect the heartbeat of a person sitting on the passenger seat 3z. In this embodiment, each of seat 3 and seat 3z corresponds to a particular seat. Seat 3 corresponds to the first seat, and seat 3z corresponds to the second seat. Alternatively, seat 3 corresponds to the second seat and seat 3z corresponds to the first seat.

The transmitter 11z outputs a transmission signal of a predetermined frequency (for example, a frequency of 900 MHz band) to the transmission antenna 12z. The transmitting antenna 12z is arranged on the front side of the vehicle traveling direction with respect to the seat 3z in the instrument panel in the vehicle compartment. The transmission antenna 12z transmits a radio signal corresponding to the transmission signal from the transmitter 11z toward the upper half of the body of the person sitting on the seat 3z.

The first receiving antenna 13az, the second receiving antenna 13bz, and the third receiving antenna 13cz are arranged to face the transmitting antenna 12z across the person sitting on the seat 3z. Specifically, the receiving antennas 13az, 13bz, and 13cz are arranged at different positions in the vehicle width direction. Each of the receiving antennas 13az, 13bz, and 13cz is configured to receive radio signals transmitted from the transmitting antenna 12z. For example, the receiving antennas 13az, 13bz, and 13cz may be embedded in the seat back 3az of the vehicle as shown in FIG.

Therefore, the transmitting antenna 12 and the receiving antennas 13a, 13b, 13c are positioned closer to the seat 3 than to the seat 3z. Also, the transmitting antenna 12z and the receiving antennas 13az, 13bz, and 13cz are positioned closer to the seat 3z than to the seat 3.

The receiver 14z amplifies the radio wave signals received by the receiving antennas 13az, 13bz, and 13cz, respectively, and outputs them to the biological information detecting device 4 as received signals P1z, P2z, and P3z. The input unit 41 of the biological information detection device 4 converts the reception signals P1, P2, P3, P1z, P2z, and P3z, which are analog signals input from the receivers 14 and 14z, into digital signals and outputs the digital signals to the processing unit 44. .

Other configurations are the same as those of the first embodiment. Next, the operation of the biological information detection system according to the present embodiment will be described, focusing on the differences from the first embodiment.

The processing unit 44 of this embodiment executes the processing shown in FIG. 10 and the processing shown in FIG. 3 for each seat. Specifically, the processing unit 44 executes the processing shown in FIG. 10 and the processing shown in FIG. If not, the processing shown in FIG. 10 and the processing shown in FIG. 3 are not executed for seat 3. Further, the processing unit 44 executes the processing shown in FIG. 10 and the processing shown in FIG. 3 for the seat 3z when a person is seated on the seat 3z. The processing shown in FIG. 10 and the processing shown in FIG. 3 are not executed for seat 3z. 10 and 3 are executed at the same timings as the processes in FIGS. 2 and 3 of the first embodiment, respectively. The process of FIG. 10 is obtained by adding steps 155 and 170 to the process of FIG.

The processing unit 44 determines whether or not a person is seated on each of the seats 3 and 3z based on, for example, detection signals from seating sensors (not shown) attached to each of the seats 3 and 3z. may

Alternatively, the processing unit 44 determines whether or not a person is seated on the seat 3 based on the signal level of one of the received signals P1, P2, and P3 when the radio signal is transmitted from the transmitting antenna 12. may Specifically, if the signal level is equal to or higher than the reference value, no one is seated on the seat 3, and if the signal level is lower than the reference value, it is determined that a person is seated on the seat 3. good. This is because when no one is seated on the seat 3, the amount of attenuation of the radio waves transmitted from the transmitter 11 before reaching the receiving antennas 13a, 13b, and 13c is low. Similarly, the processing unit 44 determines whether or not a person is seated on the seat 3z based on the signal level of one of the received signals P1z, P2z, and P3z when radio signals are transmitted from the transmitting antenna 12z. You can judge.

Thus, the processing unit 44 executes the processes of FIGS. 10 and 3 in order to calculate the heartbeat of the person 2 sitting on the seat 3, and separately calculates the heartbeat of the person 2 sitting on the seat 3z. 10 and 3 are executed in order to do so. Therefore, in this embodiment, there are two seats, the seat 3 and the seat 3z, in which the heartbeat of the seated person can be calculated.

10 and 3 for calculating the heartbeat of the person 2 sitting on the seat 3, the reception signals P1, P2, and P3 are used as described in the first embodiment. On the other hand, in the processing shown in FIGS. 10 and 3 for calculating the heartbeat of the person sitting on the seat 3z, the received signals P1z, P2z and P3z are used instead of the received signals P1, P2 and P3.

Here, the processing of FIG. 10 executed to calculate the heartbeat of the person 2 sitting on the seat 3 will be described with respect to differences from the processing of FIG.

When the loop processing for all of the receiving antennas 13a, 13b, and 13c is completed, the processing proceeds to step 155. FIG. At step 155, the processing unit 44 determines whether or not there is an occupied seat other than the seat targeted for this process (seat 3 in this case) among the seats for which the heartbeat of the seated person can be calculated. determine whether The method for determining whether or not a person is seated is as described above.

In this embodiment, if a person is seated on the seat 3z, the processing unit 44 proceeds to step 160 and selects a noise elimination antenna as in the first embodiment. On the other hand, if no one is seated on the seat 3z, the process proceeds to step 170.

At step 170, one of the receiving antennas 13az, 13bz, and 13cz corresponding to the seat determined not to be seated at step 155 (that is, seat 3z) is selected as a noise elimination antenna. Any one of the receiving antennas 13az, 13bz and 13cz may be selected. 3 for calculating the heartbeat of the person 2 sitting in the driver's seat 3, the receiving antenna corresponding to the driver's seat 3 is used as the specific antenna, and the receiving antenna corresponding to the seat 3z is used as the noise elimination antenna. is used. After step 170, the process of FIG. 10 ends. Other processes in FIG. 10 are the same as those in FIG.

10 and 3 executed to calculate the heartbeat of the person 2 seated on the seat 3z are described in the description of the processes of FIGS. 2, 10 and 3 in the first embodiment and the present embodiment. , with the prescribed replacement. In the replacement, the person 2, the seat 3, the transmitter 11, and the transmission antenna 12 are replaced with the person, the seat 3z, the transmitter 11z, and the transmission antenna 12z, respectively. In addition, the receiving antennas 13a, 13b, 13c, the receiver 14, and the received signals P1, P2, and P3 are replaced with the receiving antennas 13az, 13bz, 13cz, the receiver 14z, and the received signals P1z, P2z, and P3z.

In the present embodiment, in the process of identifying the heartbeat of the seat 3, one of the receiving antennas 13a, 13b, and 13c corresponds to the specific antenna, and one of the receiving antennas 13az, 13bz, and 13cz corresponds to the other receiving antenna. handle. Further, in the process of identifying the heartbeat of the seat 3z, one of the receiving antennas 13az, 13bz, and 13cz corresponds to the specific antenna, and one of the receiving antennas 13a, 13b, and 13c corresponds to the other receiving antenna.

As described above, when the person 2 is seated on the seat 3 and no one is seated on the seat 3z, the processing unit 44 responds to the received signal corresponding to the radio wave received by any of the receiving antennas 13az, 13bz, and 13cz. Based on this, noise is removed from the received signal corresponding to the radio wave received by the specific antenna. In this way, if no one is seated on the seat 3z, the reception antennas 13az, 13bz, and 13cz attached near the seat 3z receive radio waves that are mainly noise. Therefore, in order to calculate the biological information of the occupant seated on the seat 3, based on the received signal corresponding to the radio wave received by any of the receiving antennas 13az, 13bz, and 13cz, the reception corresponding to the radio wave received by the specific antenna is calculated. Noise can be removed from the signal.

Also, in this embodiment, the same effects can be obtained from the same configuration and operation as those of the first embodiment. It should be noted that the modification of the first embodiment as in the present embodiment can be similarly applied to the second and third embodiments.

In this embodiment, the processing unit 44 functions as an acquisition unit by executing step 110 in FIG. 10 and functions as a selection unit by executing step 150 . It also functions as a calculator by executing step 240 in FIG.

(Other embodiments)
It should be noted that the present invention is not limited to the above-described embodiments, and can be modified as appropriate. Moreover, the above-described embodiments are not unrelated to each other, and can be appropriately combined unless the combination is clearly impossible. In addition, in each of the above-described embodiments, the elements constituting the embodiment are not necessarily essential unless explicitly stated as essential or clearly considered essential in principle. In addition, in each of the above-described embodiments, when numerical values such as the number, numerical value, amount, range, etc. of the constituent elements of the embodiment are mentioned, when it is explicitly stated that they are particularly essential, and when they are clearly limited to a specific number in principle It is not limited to that specific number, except when Further, in the above embodiment, if it is described that the external environment information of the vehicle (for example, the humidity outside the vehicle) is obtained from a sensor, the sensor is discarded and the external environment information is received from a server or cloud outside the vehicle. It is also possible to Alternatively, it is also possible to eliminate the sensor, acquire related information related to the external environment information from a server or cloud outside the vehicle, and estimate the external environment information from the acquired related information. In particular, where more than one value is exemplified for a quantity, it is also possible to adopt a value between these values unless otherwise stated or clearly impossible in principle. . In addition, in each of the above-described embodiments, when referring to the shape, positional relationship, etc. of the constituent elements, the shape, It is not limited to the positional relationship or the like. In addition, the present invention allows the following modifications and modifications within the equivalent range of each of the above-described embodiments. It should be noted that the following modifications can be independently selected to be applied or not applied to the above embodiment. That is, any combination of the following modifications can be applied to the above embodiment.

The controller and techniques described in this disclosure may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by the computer program. may be Alternatively, the controls and techniques described in this disclosure may be implemented by a dedicated computer provided by configuring the processor with one or more dedicated hardware logic circuits. Alternatively, the control units and techniques described in this disclosure can be implemented by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. It may also be implemented by one or more dedicated computers configured. The computer program may also be stored as computer-executable instructions on a computer-readable non-transitional tangible recording medium.

(Modification 1)
Although the number of receiving antennas corresponding to one seat is three in the above embodiment, it may be two or four or more. If the number of receiving antennas is two, the one that is not selected as the specific antenna becomes the noise elimination antenna.

(Modification 2)
In the above embodiments, the processes of FIGS. 2, 6, and 10 are executed when the vehicle is stopped. However, the processes of FIGS. 2, 6, and 10 may be executed in situations where relatively little noise is expected, even while the vehicle is running. Scenes in which relatively little noise is expected include, for example, when the vehicle is traveling at a very low speed (for example, 10 km/h or less), and when traveling on a highway. Whether or not the vehicle is traveling on an expressway can be determined by, for example, road map data (not shown) describing the position and type of the road, and a device (not shown) that identifies the current position of the vehicle (for example, a GPS receiver). can be determined using

(Modification 3)
In the above embodiment, the heart rate is calculated based on the difference between the received signal corresponding to the radio wave received by the specific antenna and the received signal corresponding to the radio wave received by the noise eliminating antenna. However, a received signal corresponding to radio waves received by another receiving antenna that is neither the specific antenna nor the removal antenna may also be used to calculate the heart rate.

For example, the received signal corresponding to the radio wave received by the noise removal antenna is obtained from the combined value (for example, average value) of the received signal corresponding to the radio wave received by a specific antenna and the received signal corresponding to the radio wave received by another receiving antenna. may be subtracted and the result of the subtraction may be used to calculate the heart rate.

Further, for example, the composite value (for example, average value) of the received signal corresponding to the radio wave received by the noise elimination antenna and the received signal corresponding to the radio wave received by another receiving antenna is the received signal corresponding to the radio wave received by the specific antenna. It may be subtracted from the signal and the result of the subtraction used to calculate heart rate.

(Modification 4)
In the above embodiment, the SN ratio is calculated at step 130 . However, it is not necessary to calculate the SN ratio itself, and it is sufficient to calculate an amount that indicates whether or not the SN ratio is greater than the reference value. For example, what is calculated may be the square of the SN ratio, or other quantities that are strongly correlated with the SN ratio.

(Modification 5)
In the above embodiment, the receiving antennas 13a, 13b, and 13c are arranged at mutually different positions in the vehicle width direction, but may be arranged at mutually different positions in the vehicle front-rear direction, or at mutually different positions in the vehicle vertical direction. position. Alternatively, any combination thereof may be used.

(Modification 6)
In the above embodiment, the seat 3 was the driver's seat. However, the seat 3 may be the driver's seat, the passenger's seat, or the rear seat.

(Modification 7)
In the fourth embodiment, the seat 3 is the driver's seat and the seat 3z is the passenger's seat. However, the seat 3 may be the passenger's seat and the seat 3z may be the driver's seat. Further, in the above-described fourth embodiment, only the driver's seat and the passenger's seat can calculate the heart rate of the seated person. However, the biological information detection system may be configured so that the heart rate of the seated person can be calculated in all of the driver's seat, passenger's seat, and rear seat.

(Modification 8)
In the above embodiment, the SN ratio is calculated based on the frequency characteristics of the received signal. However, the SN ratio may be calculated based on the time waveform of the received signal.

(Modification 9)
In the above-described second embodiment, the slope of fluctuation of received signal strength is the absolute value of the difference between the maximum value and the minimum value in one or more time intervals, but other indices may be used. For example, the change gradient over time of the representative value of the time waveform acquired in step 110 immediately before may be used as the change gradient.

The representative value of the time waveform may be, for example, the average value of the absolute values of intensity (ie, level) over the current time interval. Alternatively, the representative value of the time waveform may be the maximum intensity value or median value within the current time interval.

Further, the slope of the change over time of the representative value may be, for example, the amount of change of the representative value in the current time interval with respect to the representative value in the previous time interval. Alternatively, the gradient of change over time of the representative value may be calculated based on the representative values in the time intervals of the current time, the previous time, and the time before last. Note that the time intervals of the previous time and the time before the time before last are the time time intervals of the time waveform acquired when the loop processing was performed on the receiving antenna of interest the time before last time and the time before last time, respectively.

Alternatively, the variation gradient of the intensity of the received signal may be the temporal variation gradient of the frequency characteristic instead of the time waveform of the received signal.

(Modification 10)
In the above embodiment, the biological information detection device 4 is mounted on the vehicle. However, the biological information detection device 4 does not necessarily have to be mounted on the vehicle. For example, the biological information detection device 4 may be implemented by a server located away from the vehicle. In that case, the biological information detection device 4 may receive the received signals P1, P2, and P3 via wireless communication.

(Modification 11)
In the above embodiment, noise is removed from the received signal corresponding to the radio wave received by the specific antenna based on the received signal corresponding to the radio wave received by the noise removing antenna. Subtraction, that is, F1-F2 is used as a method of noise removal. However, instead of subtraction, division or F1/F2 may be used.

Any method for removing noise from the received signal corresponding to the radio wave received by the specific antenna based on the received signal corresponding to the radio wave received by the noise removal antenna may be any method as long as it can be effectively removed. good.

(Modification 12)
In the above embodiment, noise is removed from the received signal corresponding to the radio wave received by the specific antenna based on the received signal corresponding to the radio wave received by the noise removing antenna. However, the heartbeat may be calculated as it is from the received signal corresponding to the radio wave received by the specific antenna without removing the noise. Even in this case, heartbeats can be calculated more accurately than before, since the specific antenna is selected as a receiving antenna corresponding to a received signal with a low SN ratio.

(Modification 13)
In the above embodiment, the heartbeat is exemplified as the biological information calculated by the biological information detection system. However, the biological information calculated by the biological information detection system need not be the heart rate, and may be, for example, the pulse rate or the respiration rate.

(Modification 14)
In the above embodiment, the biometric information detection system calculates the biometric information of the vehicle occupant. However, the person whose biometric information is to be calculated does not necessarily have to be a vehicle occupant, and may be, for example, a person in a building.

(Modification 15)
In the above-described embodiment, the receiving antennas 13a, 13b, and 13c are configured to receive radio waves that have been radiated from the transmitting antenna 12 and passed through people. However, it does not necessarily have to be that way.

For example, the receiving antennas 13a, 13b, and 13c may be configured to receive radio waves radiated from the transmitting antenna 12 and reflected by people. This is because biological information such as the heartbeat is superimposed not only on the radio waves that have passed through the person, but also on the radio waves that have reflected the person. In this case, one of the receiving antennas 13a, 13b, and 13c may also serve as the transmitting antenna.

(summary)
According to the first aspect shown in part or all of the above embodiments, the biological information detection system includes a plurality of receiving antennas arranged at mutually different positions for receiving radio waves, and radio waves radiating from the transmitting antenna. an acquisition unit that acquires a plurality of received signals corresponding to the radio waves received by the plurality of receiving antennas when received; A selection unit that selects, from the plurality of reception antennas, a specific antenna corresponding to a received signal having a ratio to noise other than the biological signal that is greater than a reference value, and a received signal that corresponds to the radio wave received by the specific antenna selected by the selection unit. and a calculator that calculates the biometric information of the person based on.

In this manner, a specific antenna corresponding to a received signal having a ratio of the biosignal to noise greater than the reference value is selected from a plurality of receiving antennas, and biometric information is calculated based on the received signal corresponding to the radio wave received by the specific antenna. be. Therefore, the biological information can be calculated by selectively using the receiving antenna receiving less noise from among the plurality of receiving antennas, so that the biological information can be calculated with higher accuracy than otherwise.

Moreover, according to the second aspect, the selection unit selects the specific antenna based on frequency characteristics of the plurality of received signals. By using the frequency characteristics of a plurality of received signals in this manner, the ratio of the biological signal to noise in the received signals can be stably calculated. This is because the frequency of the biological signal is generally stable. Similarly, by using the frequency characteristic, it is possible to easily distinguish which component is the biosignal and which component is the noise, so that the above ratio can be easily calculated.

Further, according to the third aspect, the transmission antenna and the plurality of reception antennas are mounted on a vehicle, and the selection unit receives radio waves received by the plurality of reception antennas when the vehicle is stopped. selecting the specific antenna based on the plurality of received signals according to
The calculation unit calculates the biological information based on a received signal corresponding to radio waves received by the specific antenna while the vehicle is running.

When the vehicle is stopped, noise is less likely to appear in the received signal than when the vehicle is running. Therefore, it becomes easier to correctly select a specific antenna at this time. By using the specific antennas selected in this manner while the vehicle is running, biometric information can be calculated with high accuracy even while the vehicle is running.

Further, according to the fourth aspect, the selection unit selects the specific antenna based on the plurality of received signals when the absolute value of the gradient of fluctuation in the reception level of the plurality of received signals is smaller than a reference value. pick out

For example, when a person's body moves a lot, a large change occurs in the received signal. When there is a large change in the received signal, it is difficult to accurately calculate the biosignal to noise ratio. Therefore, by selecting a specific antenna by selecting a case where the absolute value of the variation slope of the reception level of a plurality of received signals is lower than the reference value, the ratio of the biosignal to noise can be calculated more accurately.

Further, according to the fifth aspect, the calculation unit calculates the specific antenna based on the reception signal corresponding to the radio wave received by the noise removal antenna that was not selected by the selection unit among the plurality of reception antennas. removes noise from the received signal corresponding to the radio wave received by the device, and calculates the biological information based on the removed received signal.

Received signals corresponding to radio waves received by the noise elimination antenna tend to be mainly noise. This is because when multiple receiving antennas are placed at different positions, one receiving antenna often receives radio waves with biosignals superimposed thereon, and another receiving antenna receives radio waves with little biosignal superimposed thereon. is. However, in many cases, the received signal corresponding to the radio wave received by the noise elimination antenna and the received signal corresponding to the radio wave received by the specific antenna contain approximately the same amount of noise. Therefore, by removing noise from the received signal corresponding to the radio wave received by the specific antenna based on the received signal corresponding to the radio wave received by the noise elimination antenna and calculating the biological information based on the received signal after removal, Biometric information can be calculated with higher accuracy.

According to the sixth aspect, the amount of noise removed from the received signal corresponding to the radio wave received by the specific antenna increases as the received signal corresponding to the radio wave received by the noise removing antenna becomes stronger, and , are different for different noise canceling antennas.

The amount of noise included in the received signal corresponding to the radio wave received by the specific antenna and the amount of noise included in the received signal corresponding to the radio wave received by the noise eliminating antenna are often not the same. Then, the difference between the amount of noise included in the received signal corresponding to the radio wave received by the specific antenna and the amount of noise included in the received signal corresponding to the radio wave received by the noise elimination antenna is the difference between the specific antenna and the noise elimination antenna. It changes according to the positional relationship of Therefore, as described above, the amount of noise to be removed fluctuates according to the position of the noise removing antenna, thereby performing more accurate noise removal.

Further, according to the seventh aspect, the transmitting antenna and the plurality of receiving antennas are mounted on a vehicle, and when comparing a first seat and a second seat of the vehicle, the plurality of receiving antennas are the It is located closer to the first seat, the biological information detection system is provided with another receiving antenna closer to the second seat than the first seat, and the calculation unit is located at the first seat When the person is seated in the seat and no one is seated in the second seat, the radio wave received by the specific antenna is based on the received signal corresponding to the radio wave received by the other receiving antenna. Noise is removed from the corresponding received signal, and the biological information is calculated based on the removed received signal.

In this way, if no one is seated in the second seat, the other receiving antenna installed near the second seat receives radio waves that are mainly noise. Therefore, in order to calculate the biological information of the occupant seated in the first seat, noise is removed from the received signal corresponding to the radio wave received by the specific antenna based on the received signal corresponding to the radio wave received by the other receiving antennas. be able to.

Further, according to the eighth aspect, the transmitting antenna and the plurality of receiving antennas are mounted on a vehicle, the plurality of receiving antennas are attached to a specific seat of the vehicle, and the selection unit and selecting the specific antenna from the plurality of receiving antennas when the person is seated on the specific seat. In this way, since a plurality of receiving antennas are attached to the specific seat, the receiving antenna can be easily attached to a position close to the person sitting on the specific seat.

3, 3z Driver's seat 4 Biological information detection device 12, 12x Transmitting antennas 13a, 13b, 13c, 13az, 13bz, 13cz Receiving antenna 44 Processing unit

Claims (10)

a plurality of receiving antennas (13a, 13b, 13c) arranged at mutually different positions to receive radio waves;
an acquisition unit (110) for acquiring a plurality of reception signals (P1, P2, P3) corresponding to the radio waves received by the plurality of reception antennas when radio waves are radiated from the transmission antenna (12);
A specific antenna corresponding to a received signal having a ratio of a biological signal corresponding to an electric wave radiated from the transmitting antenna and reflected or transmitted through a human body to noise other than the biological signal greater than a reference value is selected from the plurality of receiving antennas. A selection unit (150) that selects from
A calculation unit (240) that calculates the biological information of the person based on the received signal corresponding to the radio wave received by the specific antenna selected by the selection unit ,
The transmitting antenna and the plurality of receiving antennas are mounted on a vehicle,
The selection unit selects the specific antenna based on the plurality of received signals corresponding to the radio waves received by the plurality of reception antennas when the vehicle is stopped,
The biometric information detection system, wherein the calculator calculates the biometric information based on a received signal corresponding to radio waves received by the specific antenna while the vehicle is running. 2. The biological information detection system according to claim 1, wherein said selection unit selects said specific antenna based on frequency characteristics of said plurality of received signals. The calculation unit calculates a received signal corresponding to the radio wave received by the specific antenna based on the received signal corresponding to the radio wave received by the noise elimination antenna that is not selected by the selection unit from among the plurality of receiving antennas. 3. The biometric information detection system according to claim 1, wherein noise is removed, and said biometric information is calculated based on said received signal after noise has been removed. The amount of noise removed from the received signal corresponding to the radio wave received by the specific antenna is greater as the received signal corresponding to the radio wave received by the noise elimination antenna is stronger, and the noise elimination antenna is different. The biological information detection system according to claim 3 . 5. The biological information detection system according to claim 4, wherein the amount of noise removed from the received signal corresponding to the radio wave received by said specific antenna decreases as said noise removal antenna is farther from said specific antenna. a plurality of receiving antennas (13a, 13b, 13c) arranged at mutually different positions to receive radio waves;
an acquisition unit (110) for acquiring a plurality of reception signals (P1, P2, P3) corresponding to the radio waves received by the plurality of reception antennas when radio waves are radiated from the transmission antenna (12);
A specific antenna corresponding to a received signal having a ratio of a biological signal corresponding to an electric wave radiated from the transmitting antenna and reflected or transmitted through a human body to noise other than the biological signal greater than a reference value is selected from the plurality of receiving antennas. A selection unit (150) that selects from
A calculation unit (240) that calculates the biological information of the person based on the received signal corresponding to the radio wave received by the specific antenna selected by the selection unit ,
The calculation unit calculates a received signal corresponding to the radio wave received by the specific antenna based on the received signal corresponding to the radio wave received by the noise elimination antenna that is not selected by the selection unit from among the plurality of receiving antennas. removing noise and calculating the biological information based on the received signal after removal;
The amount of noise removed from the received signal corresponding to the radio wave received by the specific antenna is larger as the received signal corresponding to the radio wave received by the noise removing antenna is stronger, and the noise removing antenna is removed from the specific antenna. A biological information detection system that gets smaller the further it is . The transmitting antenna and the plurality of receiving antennas are mounted on a vehicle,
Comparing a first seat (3) and a second seat (3z) of said vehicle, said plurality of receiving antennas are located closer to said first seat (3);
The biological information detection system includes other receiving antennas (13az, 13bz, 13cz) closer to the second seat than to the first seat,
The calculation unit, when the person is seated in the first seat and no one is seated in the second seat, based on the received signal corresponding to the radio wave received by the other receiving antenna 3. The biometric information detection system according to claim 1, wherein noise is removed from a received signal corresponding to radio waves received by said specific antenna, and said biometric information is calculated based on said received signal after removal of noise. a plurality of receiving antennas (13a, 13b, 13c) arranged at mutually different positions to receive radio waves;
an acquisition unit (110) for acquiring a plurality of reception signals (P1, P2, P3) corresponding to the radio waves received by the plurality of reception antennas when radio waves are radiated from the transmission antenna (12);
A specific antenna corresponding to a received signal having a ratio of a biological signal corresponding to an electric wave radiated from the transmitting antenna and reflected or transmitted through a human body to noise other than the biological signal greater than a reference value is selected from the plurality of receiving antennas. A selection unit (150) that selects from
A calculation unit (240) that calculates the biological information of the person based on the received signal corresponding to the radio wave received by the specific antenna selected by the selection unit ,
The transmitting antenna and the plurality of receiving antennas are mounted on a vehicle,
Comparing a first seat (3) and a second seat (3z) of said vehicle, said plurality of receiving antennas are located closer to said first seat (3);
The biological information detection system includes other receiving antennas (13az, 13bz, 13cz) closer to the second seat than to the first seat,
The calculation unit, when the person is seated in the first seat and no one is seated in the second seat, based on the received signal corresponding to the radio wave received by the other receiving antenna and a biological information detection system, wherein noise is removed from a received signal corresponding to radio waves received by said specific antenna, and said biological information is calculated based on said received signal after removal of noise. 9. The method of claims 1, 2, 6, and 8, wherein the selection unit selects the specific antenna based on the plurality of received signals when the absolute value of the intensity variation gradient of the plurality of received signals is smaller than a reference value. The biometric information detection system according to any one of the above. The transmitting antenna and the plurality of receiving antennas are mounted on a vehicle,
The plurality of receiving antennas are attached to specific seats of the vehicle,
The biological information detection system according to any one of claims 1 to 9 , wherein said selection unit selects said specific antenna from said plurality of receiving antennas when said person is seated on said specific seat.

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