Biometric detection system, processing device, and computer program

Abstract

To shorten the time required for detecting a living body based on a radar principle.SOLUTION: A transmission antenna 11 transmits a radio wave W toward a detection area 20. A reception antenna 12 receives the radio wave W arriving from the detection area 20 and outputs a detection signal S corresponding to the reception intensity. A processing device 13 acquires an index value corresponding to the reception intensity on the basis of the detection signal S and estimates the presence / absence of a living body 30 in the detection area 20 on the basis of a change amount of the index value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a biological detection system. The present disclosure also relates to a processing device that may be included in the system and a computer program executable by a processor mounted on the device.

Background Art

[0002] Patent Document 1 discloses a technique for estimating the presence or absence and age of a living body in a detection area by extracting a frequency component of a signal corresponding to the reception intensity of radio waves arriving from the detection area based on the radar principle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a demand for shortening the time required for detecting a living body based on the radar principle.

Means for Solving the Problems

[0005] One aspect example provided by the present disclosure is a biological detection system, a transmission antenna that transmits radio waves toward a detection area, a reception antenna that receives radio waves arriving from the detection area and outputs a detection signal corresponding to the reception intensity, a processing device that obtains an index value corresponding to the reception intensity based on the detection signal and estimates the presence or absence of a living body in the detection area based on a change amount of the index value, and includes.

[0006] One aspect example provided by the present disclosure is a processing device, a processor that causes a transmission antenna to transmit radio waves toward a detection area; an interface that receives a detection signal corresponding to a reception intensity from a reception antenna that receives radio waves arriving from the detection area; and is provided with the processor obtains an index value corresponding to the reception intensity based on the detection signal, and estimates the presence or absence of a living body in the detection area based on the amount of change in the index value.

[0007] One example of an aspect provided by the present disclosure is a computer program executable by a processor mounted on a processing device, which, when executed, causes the processing device to cause a transmission antenna to transmit radio waves toward a detection area, receive a detection signal corresponding to a reception intensity from a reception antenna that receives radio waves arriving from the detection area, obtain an index value corresponding to the reception intensity based on the detection signal, and estimate the presence or absence of a living body in the detection area based on the amount of change in the index value.

[0008] The inventor of the present application has found that there is a correlation between the vital signs of a living body and changes in the reception intensity of radio waves. By focusing on the amount of change, it is possible to estimate the presence or absence of a living body without performing frequency analysis of received radio waves, which requires a relatively long time, and thus the time required for detecting a living body based on the radar principle can be shortened.

Brief Description of the Drawings

[0009]

Figure 1

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Embodiments for Carrying Out the Invention

[0010] Examples of embodiments will be described in detail below with reference to the accompanying drawings. In each of the drawings used in the following description, the scale is appropriately changed in order to make each element recognizable in size.

[0011] FIG. 1 illustrates the functional configuration of a biological detection system 10 according to an example of an embodiment. The biological detection system 10 is configured to detect a living body 30 located within a detection area 20 based on the radar principle.

[0012] The biological detection system 10 includes a transmission antenna 11. The transmission antenna 11 is configured to transmit radio waves W toward the detection area 20. The frequency of the radio waves W can be determined as appropriate. The radio waves W according to this example have a frequency classified as a microwave.

[0013] The biological detection system 10 includes a reception antenna 12. The reception antenna 12 is configured to receive radio waves W arriving from the detection area 20. That is, the reception antenna 12 is configured to have sensitivity to the frequency of the radio waves W.

[0014] The reception antenna 12 is configured to output a detection signal S corresponding to the received radio wave intensity. The detection signal S may be an analog signal or a digital signal according to the specifications of the reception antenna 12.

[0015] The biological detection system 10 includes a processing device 13. The processing device 13 includes an input interface 131, a processor 132, and an output interface 133.

[0016] The input interface 131 is configured as a hardware interface capable of receiving the detection signal S. When the detection signal S is an analog signal, the input interface 131 includes an appropriate conversion circuit including an A / D converter.

[0017] The processor 132 is configured to output a transmission control signal TC for causing the transmission antenna 11 to transmit the radio wave W from an output interface 133 configured as a hardware interface. The transmission control signal TC includes information capable of specifying the time point at which the radio wave W is transmitted to the transmission antenna 11.

[0018] The transmission control signal TC may be an analog signal or a digital signal according to the specifications of the transmission antenna 11. When the transmission control signal TC is an analog signal, the output interface 133 includes an appropriate conversion circuit including a D / A converter. This description is similarly applicable to other signals that can be output from the output interface 133 described later.

[0019] The processor 132 of the processing device 13 is configured to execute a process of estimating the presence or absence of the living body 30 in the detection area 20 based on the detection signal S. The details of the process will be described with reference to FIGS. 2 and 3.

[0020] The processor 132 of the processing device 13 causes the transmission antenna 11 to transmit the radio wave W by outputting the transmission control signal TC from the output interface 133. The radio wave W is reflected by an object existing in the detection area 20 and received by the reception antenna 12.

[0021] The processor 132 acquires an index value corresponding to the radio wave intensity received by the reception antenna 12 based on the detection signal S output from the reception antenna 12. Examples of the index value include the value of the radio wave intensity itself and a function of the radio wave intensity.

[0022] FIG. 2 shows the change over time of the index value obtained when a child human as an example of the living body 30 is present in the detection area 20. Body movements associated with periodic vital signs (such as heartbeat and breathing) unique to the living body 30 are reflected in the periodic change of the received radio wave intensity. The processor 132 estimates the presence or absence of the living body 30 in the detection area 20 based on the amount of change in the index value corresponding to the received radio wave intensity.

[0023] Specifically, when it is determined that the amount of change exceeds a predefined first threshold value, the presence of the living body 30 in the detection area 20 is estimated. The amount of change can be specified by, for example, the difference between the maximum value and the minimum value, or the difference between the median value or the average value (if available) and the extreme value.

[0024] The inventor of the present application has found that there is a correlation between the vital signs of the living body 30 and the change in the received intensity of the radio wave. By focusing on the amount of change, it is possible to estimate the presence or absence of the living body 30 without performing a frequency analysis of the received radio wave, which takes a relatively long time, thus shortening the time required for detecting a living body based on the radar principle.

[0025] FIG. 3 shows the change over time of the index value obtained when an adult human as an example of the living body 30 is present in the detection area 20. It can be seen that the amount of change in the index value is larger compared to the case of the child illustrated in FIG. 2.

[0026] The magnitude of the change in the radio wave reception intensity corresponds to the area of the part of the living body 30 that causes the change. Examples of such parts include the chest, abdomen, etc. that are periodically displaced by breathing, etc. Since the area of this part increases as the body grows, the amount of change in the radio wave reception intensity is larger in adults than in children.

[0027] The processor 132 of the processing device 13 can be configured to estimate the age of the living body 30 based on the amount of change in the index value obtained as described above. The term "age" used in this specification is intended to include not only specific age values but also age categories such as "infant", "child", "adult", "elderly", and "teenager".

[0028] The relationship between the magnitude of the index value and age is stored in advance in a storage (not shown) in the form of a table or a function, and can be referred to by the processor 132 during estimation.

[0029] According to such a configuration, the age of the living body 30 can be estimated without performing frequency analysis that requires a relatively long time.

[0030] As illustrated in FIG. 4, the biological detection system 10 can be mounted on a vehicle 40. In this case, the detection area 20 is set to include the interior of the passenger compartment 41 of the vehicle 40. The vehicle 40 is an example of a moving body. The passenger compartment 41 is an example of a living room.

[0031] According to such a configuration, the living body 30 located in the passenger compartment 41 can be detected. For example, when the amount of change in the index value obtained as described above is greater than the first threshold value and less than the second threshold value, it can be estimated that the detected living body 30 is a child or a pet. The second threshold value can be determined so as to correspond to the amount of change in the index value that can be estimated as an adult described with reference to FIG. 3. Thereby, for example, it is possible to estimate a state in which a child or a pet is left unattended in the passenger compartment 41.

[0032] As illustrated in FIG. 1, when it is estimated based on the detection signal S that a child or a pet exists in the detection area 20, the processor 132 can be configured to output a control signal CT from the output interface 133. The control signal CT is configured to cause the controlled device 50 to perform a predetermined operation. Examples of the controlled device 50 include a notification device, a communication device, and the like. A child or a pet is an example of a living body classified into a specific type.

[0033] For example, when it is estimated that a child or a pet has been left unattended in the passenger compartment 41, at least one of visual notification and auditory notification can be given to the user or the surroundings of the vehicle 40 by the notification device mounted on the vehicle 40. Examples of notification methods include sounding the horn of the vehicle 40, turning on all lighting devices of the vehicle 40, moving to a place where people are present by automatic driving, and the like. In addition to or instead of this, the communication device mounted on the vehicle 40 can notify the mobile device carried by the user of the vehicle 40 of the estimated fact. An image taken inside the passenger compartment 41 may be transmitted together with the notification of the fact.

[0034] In addition to or instead of the above notification, an intervention process for changing the environment inside the passenger compartment 41 may be performed. Examples of the intervention process include automatically controlling an air conditioner (heating and cooling), opening a window of the vehicle 40, unlocking a door of the vehicle 40, opening a door of the vehicle 40, opening and closing a sunshade, and the like.

[0035] Note that if the distance to the detection target is known as in the case where the living body 30 is seated on the rear seat 42 of the vehicle 40, the age of the living body 30 can be directly estimated from the change amount of the index value. However, when the distance to the detection target is not constant, it is difficult to accurately estimate the age based only on the change amount of the index value. For example, there may be a case where it is impossible to distinguish between the chest area of a child located at a short distance and the chest area of an adult located at a long distance.

[0036] On the other hand, since the time point when the radio wave W is transmitted from the transmission antenna 11 can be specified based on the transmission control signal TC output from the processing device 13, if the time point when the radio wave W reflected by the living body 30 is received by the reception antenna 12 can be specified, the distance to the living body 30 can be specified based on the elapsed time.

[0037] Therefore, if the detection signal S is configured to include information indicating the time when the radio wave W is received by the receiving antenna 12, the processor 132 can specify the distance to the living body 30 by referring to the information. The processor 132 can be configured to estimate the age of the living body 30 while referring to the distance. Specifically, the relationship between the magnitude of the index value, the distance to the living body 30, and the age of the living body 30 can be stored in a storage (not shown) in the form of a table or a function in advance. The processor 132 can more accurately estimate the age of the living body 30 by referring to the table or the function based on the specified distance to the living body 30.

[0038] As illustrated in FIG. 5, the age of the living body 30 can be divided into at least three categories. The second category is a lower age than the first category. The third category is a higher age than the first category. Examples of combinations of the second category and the third category include "child" and "adult", "infant" and "child", "elderly" and "adult", etc. The second category is assigned to an age having a smaller physique than the third category.

[0039] FIG. 6 illustrates the flow of a process for estimating the age of the living body 30 based on the above-described categories. The processor 132 of the processing device 13 estimates the age of the living body 30 based on the amount of change in the index value corresponding to the received radio wave intensity described above (STEP1).

[0040] Subsequently, the processor 132 determines whether the estimated age belongs to the first category (STEP2). If it is determined that the estimated age belongs to the first category (YES in STEP2), the processor 132 re-estimates the age of the living body 30 (STEP3). As illustrated in FIG. 5, the re-estimation is performed so as not to include the first category. That is, the re-estimated age of the living body 30 belongs to either the second category or the third category.

[0041] If it is determined that the age estimated by the process of STEP1 does not belong to the first category (NO in STEP2), the processor 132 ends the process.

[0042] For example, it may be difficult to determine whether a living body belongs to the second category or the third category, such as a relatively large-sized child and a relatively small-sized adult. However, according to the above configuration, an intermediate first category to which such a difficult-to-distinguish living body 30 may belong is set, so that a living body belonging to the second category or the third category can be reliably discriminated. Thereby, appropriate measures (for example, notification when estimated to be a child) corresponding to the estimated category can be quickly carried out.

[0043] The re-estimation process is preferably performed based on an index value different from the index value corresponding to the received radio wave intensity. As an example, age re-estimation can be performed by performing frequency analysis of the received radio wave W.

[0044] According to such a configuration, the age of a living body 30 for which it is difficult to determine whether it belongs to the second category or the third category based on the estimation based on the index value corresponding to the received radio wave intensity can be accurately discriminated into the second category or the third category.

[0045] Note that the estimation based on the index value corresponding to the received radio wave intensity may be repeated until discrimination into the second category or the third category is possible.

[0046] The processor 132 having the various functions described so far can be realized by a general-purpose microprocessor that operates in cooperation with a general-purpose memory. Examples of the general-purpose microprocessor can include a CPU, an MPU, and a GPU. Examples of the general-purpose memory can include a ROM and a RAM. In this case, a computer program for realizing the function can be stored in the ROM. The ROM is an example of a non-transitory computer-readable medium storing a computer program. The general-purpose microprocessor designates at least a part of the computer program stored on the ROM and expands it onto the RAM, and executes the above-described processing in cooperation with the RAM. The above computer program may be pre-installed in the general-purpose memory, or may be downloaded from an external server via a communication network and installed in the general-purpose memory. In this case, the external server is an example of a computer-readable medium storing a computer program.

[0047] The processor 132 may also be realized by an application-specific integrated circuit capable of executing the above computer program, such as a microcontroller, an ASIC, or an FPGA. In this case, the above computer program is pre-installed in a storage element included in the application-specific integrated circuit. The storage element is an example of a computer-readable medium storing a computer program. The processor 132 may also be realized by a combination of a general-purpose microprocessor and an application-specific integrated circuit.

[0048] Each of the configurations described so far is merely an example for facilitating the understanding of the present disclosure. Each configuration example can be appropriately changed and combined with other configuration examples without departing from the spirit of the present disclosure.

[0049] In the above-described embodiment, one receiving antenna 12 is assigned to one transmitting antenna 11. However, the number of receiving antennas 12 assigned to one transmitting antenna 11 may be plural. As long as at least one receiving antenna 12 is assigned to one transmitting antenna 11, the number of transmitting antennas 11 included in the biological detection system 10 may be two or more.

[0050] The form of the vehicle 40 in FIG. 4 is merely illustrative. The number of seats and wheels in the vehicle 40 on which the biological detection system 10 is mounted can be determined as appropriate. Note that the biological detection system 10 does not necessarily have to be mounted on the vehicle 40. Examples of other moving bodies on which the biological detection system 10 is mounted include railways, airplanes, ships, etc. The moving body does not necessarily require a driver. The position and size of the detection area 20 can be determined as appropriate according to the type of the moving body.

[0051] The biological detection system 10 does not necessarily have to be mounted on a moving body. The biological detection system 10 can be installed in an appropriate house, facility, equipment, etc. The position and size of the detection area 20 can be determined as appropriate according to the installation location.

[0052] Each of the configurations listed below also constitutes a part of the present disclosure. Item 1: A transmitting antenna that transmits radio waves toward a detection area, A receiving antenna that receives radio waves arriving from the detection area and outputs a detection signal corresponding to the received intensity, A processing device that obtains an index value corresponding to the received intensity based on the detection signal and estimates the presence or absence of a living body in the detection area based on the change amount of the index value, and a biological detection system. Item 2: The processing device estimates the age of the living body based on the change amount of the index value, The biological detection system according to Item 1. Item 3: The age includes a first category, a second category that is younger than the first category, and a third category that is older than the first category, When it is estimated that the age of the living body belongs to the first category, the processing device executes re-estimation processing. The living body detection system according to Item 2. Item 4: In the re-estimation processing, the age of the living body is estimated based on an index value different from the index value corresponding to the reception intensity. The living body detection system according to Item 3. Item 5: The processing device identifies the distance to the living body and estimates the age of the living body with reference to the distance. The living body detection system according to any one of Items 2 to 4. Item 6: When it is estimated that the living body classified into a specific type exists in the detection area, the processing device causes the controlled device to perform a predetermined operation. The living body detection system according to any one of Items 1 to 5. Item 7: The detection area is set in the living room of the moving body. The living body detection system according to any one of Items 1 to 6. Item 8: The radio wave has a frequency classified as a microwave. The living body detection system according to any one of Items 1 to 7.

Explanation of Signs

[0053] 10: Living body detection system, 11: Transmission antenna, 12: Reception antenna, 13: Processing device, 131: Input interface, 132: Processor, 20: Detection area, 30: Living body, 40: Vehicle, 41: Passenger compartment, 50: Controlled device, S: Detection signal, W: Radio wave

Claims

1. A transmitting antenna that transmits radio waves toward a detection area, A receiving antenna that receives radio waves arriving from the detection area and outputs a detection signal corresponding to the reception intensity, A processing device that obtains an index value corresponding to the reception intensity based on the detection signal and estimates the presence or absence of a living body in the detection area based on the amount of change in the index value, A living body detection system comprising: A living body detection system.

2. The processing device estimates the age of the living body based on the amount of change in the index value. The living body detection system according to claim 1.

3. The age includes a first category, a second category that is younger than the first category, and a third category that is older than the first category. When it is estimated that the age of the living body belongs to the first category, the processing device executes a re-estimation process. The living body detection system according to claim 2.

4. In the re-estimation process, the age of the living body is estimated based on an index value different from the reception intensity. The living body detection system according to claim 3.

5. The processing device specifies the distance to the living body and estimates the age of the living body with reference to the distance. The living body detection system according to claim 2.

6. When the presence of the living body classified into a specific type in the detection area is estimated, the processing device causes a controlled device to perform a predetermined operation. The living body detection system according to claim 1.

7. The detection area is set in the living room of a moving body. The living body detection system according to claim 1.

8. The radio wave has a frequency classified as a microwave. The living body detection system according to claim 1.

9. A processor that causes a transmitting antenna to transmit radio waves toward a detection area, An interface that receives a detection signal corresponding to the reception intensity from a receiving antenna that receives radio waves arriving from the detection area, Comprising: The processor obtains an index value corresponding to the reception intensity based on the detection signal and estimates the presence or absence of a living body in the detection area based on the amount of change in the index value. A processing device.

10. A computer program executable by a processor mounted on a processing device, When executed, the processing device Causes a transmitting antenna to transmit radio waves toward a detection area, Receives a detection signal corresponding to the reception intensity from a receiving antenna that receives radio waves arriving from the detection area, Obtain an index value corresponding to the reception intensity based on the detection signal, Estimate the presence or absence of a living body in the detection area based on the amount of change in the index value, A computer program.

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