Biological detection system, processing device, and non-transitory computer-readable medium

Abstract

A transmission antenna (11) transmits radio waves (W) toward a detection region (20). A reception antenna (12) receives radio waves (W) coming from the detection region (20) and outputs a detection signal (S) corresponding to the reception intensity. This processing device (13) acquires an index value corresponding to the reception intensity on the basis of the detection signal (S), and estimates the presence or absence of a living body (30) in the detection region (20) on the basis of the amount of change in the index value.

Description

Liveness detection system, processing device, and non-transitory computer-readable medium

[0001] The present disclosure relates to a biometric detection system, a processing device that may be included in the system, and a non-transitory computer-readable medium having stored thereon a computer program executable by a processor included in the device.

[0002] Japanese Patent Application Publication No. 2010-162969 discloses a technology for estimating the presence or absence of a living body and its age in a detection area by extracting the frequency components of a signal corresponding to the reception strength of radio waves arriving from the detection area based on the radar principle.

[0003] There is a demand for reducing the time required for detecting living organisms based on radar principles.

[0004] One example aspect that the present disclosure can provide is a living organism detection system comprising: 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 strength; and a processing device that obtains an index value corresponding to the reception strength based on the detection signal and estimates the presence or absence of a living organism in the detection area based on the amount of change in the index value.

[0005] One example of an aspect that can be provided by the present disclosure is a processing device comprising: a processor that causes a transmitting antenna to transmit radio waves toward a detection area; and an interface that receives a detection signal corresponding to a reception strength from a receiving antenna that receives radio waves arriving from the detection area, wherein the processor obtains an index value corresponding to the reception strength 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.

[0006] One example aspect that the present disclosure can provide is a non-transitory computer-readable medium storing a computer program executable by a processor mounted on a processing device, wherein execution of the computer program causes the processing device to: cause a transmitting antenna to transmit radio waves toward a detection area; receive a detection signal corresponding to the reception strength from a receiving antenna that receives the radio waves arriving from the detection area; obtain an index value corresponding to the reception strength based on the detection signal; and estimate the presence or absence of a living organism in the detection area based on the amount of change in the index value.

[0007] The inventors of this application have discovered that there is a correlation between vital signs of a living body and changes in the strength of received 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 the received radio waves, which takes a relatively long time, thereby shortening the time required for detecting a living body based on the radar principle.

[0008] 5 illustrates a functional configuration of a living body detection system according to an embodiment. 6 illustrates an example of processing executed by the processing device of FIG. 1. 7 illustrates another example of processing executed by the processing device of FIG. 1. 8 illustrates a vehicle equipped with the living body detection system of FIG. 1. 9 illustrates an example of age estimation processing executed by the processing device of FIG. 1. 10 illustrates a flow of the age estimation processing of FIG. 5.

[0009] The following detailed description of exemplary embodiments will be given with reference to the accompanying drawings. In the drawings used in the following description, the scale of each element is appropriately changed so that it can be recognized.

[0010] 1 illustrates the functional configuration of a living organism detection system 10 according to an embodiment. The living organism detection system 10 is configured to detect a living organism 30 located within a detection area 20 based on the radar principle.

[0011] The biological detection system 10 includes a transmitting antenna 11. The transmitting antenna 11 is configured to transmit radio waves W toward a detection area 20. The frequency of the radio waves W can be determined as appropriate. The radio waves W in this example have a frequency that is classified as a microwave.

[0012] The biological detection system 10 includes a receiving antenna 12. The receiving antenna 12 is configured to receive radio waves W arriving from a detection area 20. In other words, the receiving antenna 12 is configured to be sensitive to the frequency of the radio waves W.

[0013] The receiving antenna 12 is configured to output a detection signal S corresponding to the intensity of the received radio wave. The detection signal S may be an analog signal or a digital signal depending on the specifications of the receiving antenna 12.

[0014] 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.

[0015] 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.

[0016] The processor 132 is configured to output, from an output interface 133 configured as a hardware interface, a transmission control signal TC for causing the transmitting antenna 11 to transmit radio waves W. The transmission control signal TC includes information capable of specifying the time when the transmitting antenna 11 is to transmit radio waves W.

[0017] The transmission control signal TC may be an analog signal or a digital signal depending on the specifications of the transmitting 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 also applies to other signals that can be output from the output interface 133, which will be described later.

[0018] The processor 132 is configured to execute a process for estimating the presence or absence of a living organism 30 in the detection area 20 based on the detection signal S. The process will be described in detail with reference to FIGS.

[0019] The processor 132 of the processing device 13 outputs a transmission control signal TC from the output interface 133, thereby causing the transmitting antenna 11 to transmit radio waves W. The radio waves W are reflected by an object present in the detection area 20 and received by the receiving antenna 12.

[0020] The processor 132 acquires an index value corresponding to the radio wave intensity received by the receiving antenna 12 based on the detection signal S output from the receiving antenna 12. Examples of the index value include the value of the radio wave intensity itself, as well as a function of the radio wave intensity.

[0021] 2 shows the change over time in the index value acquired when a human child, as an example of the living body 30, is present in the detection area 20. Body movements associated with periodic vital signs (heart rate, breathing, etc.) specific to the living body 30 are reflected in periodic changes in the received radio wave strength. 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 strength.

[0022] Specifically, when it is determined that the amount of change exceeds a predetermined first threshold, the presence of the living organism 30 is estimated in the detection area 20. The amount of change can be identified by the difference between the maximum value and the minimum value, or the difference between the median or average value (if obtainable) and the extreme value, or the like.

[0023] The inventors of the present application have found that there is a correlation between the vital signs of the living body 30 and changes in the received radio wave strength. By focusing on the amount of change, it is possible to estimate the presence or absence of the living body 30 without performing frequency analysis of the received radio waves, which takes a relatively long time, thereby shortening the time required for detecting a living body based on the radar principle.

[0024] 3 shows the change over time in the index value acquired when an adult human, as an example of a living body 30, is present in the detection area 20. Compared to the case of a child illustrated in FIG. 2, it can be seen that the amount of change in the index value is greater.

[0025] The magnitude of the change in 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 and abdomen, which are subject to periodic displacement due to breathing, etc. The area of ​​such parts increases as the body grows, so the amount of change in radio wave reception intensity is greater in adults than in children.

[0026] 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 acquired 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."

[0027] The relationship between the magnitude of the index value and age is stored in advance in the form of a table or function in a storage device (not shown), and can be referenced by the processor 132 when making an estimation.

[0028] According to this configuration, the age of the living body 30 can be estimated without performing frequency analysis, which takes a relatively long time.

[0029] 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 a 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 space.

[0030] With this configuration, it is possible to detect a living organism 30 located in the vehicle interior 41. For example, if the amount of change in the index value acquired as described above is greater than the first threshold value and less than the second threshold value, it can be assumed that the detected living organism 30 is a child or a pet. The second threshold value can be set to correspond to the amount of change in the index value that can be assumed to indicate an adult, as described with reference to FIG. 3 . This makes it possible to estimate, for example, that a child or a pet has been left behind in the vehicle interior 41.

[0031] 1 , the processor 132 can be configured to output a control signal CT from the output interface 133 when it is estimated that a child or a pet is present in the detection area 20 based on the detection signal S. The control signal CT is configured to cause the controlled device 50 to perform a predetermined operation. Examples of the controlled device 50 include an alarm device and a communication device. A child or a pet is an example of a living organism classified into a specific type.

[0032] For example, if it is estimated that a child or a pet has been left behind in the vehicle interior 41, an alarm device mounted on the vehicle 40 may provide at least one of a visual alarm and an audible alarm to the user of the vehicle 40 or the surrounding area. Examples of notification methods include honking the horn of the vehicle 40, turning on all lighting devices of the vehicle 40, or automatically driving the vehicle 40 to a location where people are present. Additionally or alternatively, a communication device mounted on the vehicle 40 may notify a mobile device carried by the user of the vehicle 40 of the estimated fact. An image captured inside the vehicle interior 41 may be transmitted together with the notification of the fact.

[0033] In addition to or instead of the above-described notification, an intervention process may be performed to change the environment inside the vehicle compartment 41. Examples of the intervention process include automatically controlling an air conditioning device (heating and cooling), opening a window of the vehicle 40, unlocking a door of the vehicle 40, opening or closing a sunshade, and the like.

[0034] If the distance to the detection target is known, such as when the living body 30 is seated in the back seat 42 of the vehicle 40, the age of the living body 30 can be estimated directly from the change in the index value. However, if the distance to the detection target is not constant, it is difficult to accurately estimate the age based only on the change in the index value. For example, there are cases where it is impossible to distinguish between the chest area of ​​a child located close by and the chest area of ​​an adult located far away.

[0035] On the other hand, the time when radio waves W are transmitted from the transmitting antenna 11 can be determined based on the transmission control signal TC output from the processing device 13, so if the time when the radio waves W reflected by the living body 30 are received by the receiving antenna 12 can be determined, the distance to the living body 30 can be determined based on the elapsed time.

[0036] Therefore, if the detection signal S is configured to include information indicating the time when the radio waves W were received by the receiving antenna 12, the processor 132 can identify 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 advance in the form of a table or function in storage (not shown). The processor 132 can more accurately estimate the age of the living body 30 by referring to the table or function based on the identified distance to the living body 30.

[0037] As illustrated in Fig. 5, the age of the living body 30 can be divided into at least three categories. The second category is younger than the first category. The third category is older than the first category. Examples of combinations of the second and third categories include "child" and "adult," "infant" and "child," and "elderly" and "adult." The second category is assigned to ages with smaller physical builds than the third category.

[0038] 6 illustrates a process flow for estimating the age of the living body 30 based on the above-described classification. 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 strength (STEP 1).

[0039] Next, the processor 132 determines whether the estimated age belongs to the first category (STEP 2). If it is determined that the estimated age belongs to the first category (YES in STEP 2), the processor 132 re-estimates the age of the living body 30 (STEP 3). 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.

[0040] If it is determined that the age estimated by the processing in STEP 1 does not belong to the first category (NO in STEP 2), processor 132 ends the processing.

[0041] For example, there may be cases where it is difficult to determine whether the age of a living body belongs to the second or third category, such as between a relatively large child and a relatively small adult. However, with the above-described configuration, an intermediate first category is set to which such difficult-to-distinguish living body 30 may belong, so that living bodies can be reliably distinguished as belonging to the second or third category. This allows appropriate measures to be taken promptly according to the estimated category (e.g., a notification when the living body is estimated to be a child).

[0042] The re-estimation process is preferably performed based on an index value different from the index value corresponding to the received radio wave strength. As an example, the age can be re-estimated by performing a frequency analysis of the received radio wave W.

[0043] With this configuration, the age of a living body 30, which is difficult to determine whether it belongs to the second or third category by estimation based on an index value corresponding to the received radio wave strength, can be accurately distinguished into the second or third category.

[0044] Note that estimation based on the index value corresponding to the received radio wave intensity may be repeated until discrimination into the second or third category is possible.

[0045] The processor 132 having the various functions described above may be realized by at least one general-purpose microprocessor operating in cooperation with at least one general-purpose memory. Examples of general-purpose microprocessors include a CPU, an MPU, and a GPU. Examples of general-purpose memory include a ROM and a RAM. In this case, a computer program for implementing the corresponding functions may be stored in the ROM. The ROM is an example of a non-transitory computer-readable medium on which a computer program is stored. The general-purpose microprocessor specifies at least a portion of the computer program stored in the ROM, deploys it on the RAM, and executes the above-described processing in cooperation with the RAM. The 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 non-transitory computer-readable medium on which a computer program is stored.

[0046] The processor 132 may be realized by at least one dedicated integrated circuit capable of executing the computer program. Examples of the dedicated integrated circuit include a microcontroller, an ASIC, and an FPGA. In this case, the computer program is pre-installed in a memory element included in the dedicated integrated circuit. The memory element is an example of a non-transitory computer-readable medium on which a computer program is stored. The processor 132 may be realized by a combination of a general-purpose microprocessor and a dedicated integrated circuit.

[0047] The configurations described above are merely examples to facilitate understanding of the present disclosure. Each configuration example can be appropriately modified and combined with other configuration examples without departing from the spirit of the present disclosure.

[0048] In the above embodiment, one receiving antenna 12 is assigned to one transmitting antenna 11. However, a plurality of receiving antennas 12 may be assigned to one transmitting antenna 11. 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.

[0049] The form of the vehicle 40 in Figure 4 is merely an example. The number of seats and wheels in the vehicle 40 in which the living body detection system 10 is installed can be determined as appropriate. Note that the living body detection system 10 does not necessarily have to be installed in a vehicle 40. Examples of other moving objects in which the living body detection system 10 is installed include trains, airplanes, and ships. The moving object does not need to require a driver. The position and size of the detection area 20 can be determined as appropriate depending on the type of moving object.

[0050] The biological detection system 10 does not necessarily need to be mounted on a mobile object. The biological detection system 10 can be installed in a suitable home, facility, equipment, etc. The position and size of the detection area 20 can be determined appropriately depending on the installation location.

[0051] The contents of Japanese Patent Application No. 2024-004987 filed on January 17, 2024 are incorporated by reference as part of this disclosure.

Claims

1. A living body detection system comprising: 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 a reception intensity; and 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.

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

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. The processing device executes a re-estimation process when it is estimated that the age of the living body belongs to the first category. 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 any one of claims 2 to 4.

6. The processing device causes a controlled device to perform a predetermined operation when the presence of the living body classified into a specific type in the detection area is estimated. The living body detection system according to any one of claims 1 to 5.

7. The detection area is set in a living room of a moving body. The living body detection system according to any one of claims 1 to 6.

8. The radio waves have a frequency classified as a microwave. The living body detection system according to any one of claims 1 to 7.

9. A processing device comprising: a processor that causes a transmission antenna to transmit radio waves toward a detection area; and 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. 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 a change amount of the index value. A non-transitory computer-readable medium storing a computer program executable by a processor mounted on a processing device, wherein when the computer program is executed, the processing device causes a transmission antenna to transmit radio waves toward a detection area, receives a detection signal corresponding to a reception intensity from a reception antenna that receives radio waves arriving from the detection area, 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.

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