Occupant detection device and occupant detection method

Abstract

The present invention is provided with: an occupant candidate vibration displacement calculation unit (302) that, on the basis of sensor information indicating a phase change of a reflected wave obtained when a radio wave radiated by a radio wave sensor (100) toward a target seat region in the cabin of a moving body is reflected by a reflection object in the target seat region, calculates, for each target seat, a temporal change in vibration displacement of the reflection object; a moving body vibration displacement calculation unit (304) that, on the basis of vibration information acquired by one vibration acquisition device (200) which is provided on the moving body and acquires vibration information relating to body vibration of the moving body, calculates a temporal change in vibration displacement of the moving body; a seat vibration displacement calculation unit (305) that, on the basis of the temporal change in the vibration displacement of the moving body, calculates, for each target seat, a temporal change in vibration displacement of the target seat; and an occupant detection unit that, on the basis of the temporal change in the vibration displacement of the reflection object and the temporal change in the vibration displacement of each of the target seats, detects the presence or absence of an occupant in the moving body with consideration to the vibration of each of the target seats.

Description

Occupant detection device and occupant detection method

[0001] The present disclosure relates to an occupant detection device and an occupant detection method.

[0002] In a mobile body, a technology is being developed to detect the presence or absence of an occupant in the mobile body by using a radio wave sensor to capture human movements such as breathing from information based on a radio wave emitted from the radio wave sensor toward the interior of the mobile body and reflected by an object present in the interior. Meanwhile, a technology is known for suppressing the influence of body movements other than the occupant's pulse (for example, movements due to vibration of the mobile body, movements due to the occupant's will, etc.) as a technology for acquiring biometric information of the occupant of the mobile body with high accuracy. For example, Patent Document 1 discloses a biometric information acquisition system that includes a first sensor (Doppler sensor) that detects a heartbeat signal corresponding to the heartbeat of an occupant of a moving body by transmitting radio waves toward the occupant and receiving reflected waves from the occupant, a second sensor (FMCW (Frequency Modulated Continuous Wave): frequency modulated continuous wave radar) that acquires distance information regarding the distance between the first sensor and the occupant, a gain processing unit that performs gain processing to amplify or attenuate the signal based on the distance, and a generation unit that generates biometric information regarding the occupant's heartbeat from the gain-processed heartbeat signal.

[0003] Japanese Patent Application Laid-Open No. 2022-116583

[0004] In the conventional technology using a radio wave sensor to detect the presence or absence of an occupant as described above, for example, when a vehicle is idling or shaking occurs due to vibrations on a rough road, the vibrations of the vehicle itself are transmitted to the seat, and the radio wave sensor detects the vibrations of the seat. This vibration of the seat becomes noise other than the occupant's breathing and other movements, which may result in a false detection of an occupant being present when there is no occupant. Note that in the conventional technology, for example, when an attempt is made to remove noise other than the occupant's movements as described above by using a method of amplifying or attenuating a signal from a heartbeat signal detected by a first sensor in a biometric information acquisition system disclosed in Patent Document 1, there is a possibility that an amplification gain is applied to sensor information when there is no occupant, thereby amplifying the noise itself, or that an attenuation gain is applied to sensor information when there is an occupant, which may also attenuate radio waves reflected from the occupant, thereby still resulting in a false detection of an occupant.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide an occupant detection device that improves the accuracy of occupant detection in a moving body.

[0006] The occupant detection device of the present disclosure includes an occupant candidate vibration displacement calculation unit that calculates, for each target seat, the change in vibration displacement of a reflecting object, which is the source of the reflected wave, based on sensor information indicating the phase change of the reflected wave reflected by a reflecting object that may include the occupant and the target seat within the target seat area, when the radio wave sensor emits radio waves toward a target seat area including a target seat set for each target seat that is to be targeted for detecting the presence or absence of an occupant in the cabin of the mobile body; a moving body vibration displacement calculation unit that calculates the change in vibration displacement of the moving body based on vibration information acquired by a vibration acquisition device that is provided in the mobile body and acquires vibration information related to the vibration of the main body of the mobile body; a seat vibration displacement calculation unit that calculates, for each target seat, the change in vibration displacement of the target seat based on the change in vibration displacement of the moving body calculated by the moving body vibration displacement calculation unit; and an occupant detection unit that detects the presence or absence of an occupant in the mobile body, taking into account the vibration of each target seat, based on the change in vibration displacement of the reflecting object calculated by the occupant candidate vibration displacement calculation unit and the change in vibration displacement of each target seat calculated by the seat vibration displacement calculation unit.

[0007] According to the present disclosure, an occupant detection device can improve the accuracy of occupant detection in a moving body.

[0008] 3A is a diagram illustrating an example of the physical configuration of an occupant detection device, a radio wave sensor, and a vibration acquisition device according to the first embodiment. It is a diagram illustrating an example of the configuration of an occupant detection device according to the first embodiment. It is a diagram illustrating an example of a method in which a seat vibration displacement calculation unit calculates a time change in seat vibration displacement of a target seat in the first embodiment. FIG. 3A is a diagram illustrating an example of the state of the interior of a vehicle. FIG. 3B is a diagram illustrating an example of components of a unit vector in the x' direction of a radio wave sensor axis pointing to each seat direction in a coordinate system based on the coordinate axes of an acceleration sensor and unit vectors in the y' and z' directions of new coordinate axes perpendicular to the x' direction. FIG. 3C is a diagram illustrating an example of a general formula for basis vector transformation used when the seat vibration displacement calculation unit calculates the seat vibration displacement. It is a diagram illustrating an example of a process for detecting the presence or absence of an occupant in a vehicle by the occupant detection unit according to the first embodiment. FIG. 4A is a diagram illustrating an example of subtraction of a time change in seat vibration displacement from a time change in occupant candidate vibration displacement performed by a noise removal unit. FIG. 4B is a diagram illustrating another example of subtraction of a time change in seat vibration displacement from a time change in occupant candidate vibration displacement performed by the noise removal unit. 11 is a flowchart for explaining the operation of the occupant detection device according to the first embodiment. FIG. 12 is a flowchart for explaining details of the occupant detection process by the occupant detection unit in step ST5 of FIG. 5. FIG. 13 is a flowchart for explaining details of the warning output control process by the occupant detection unit in step ST6 of FIG. 5. FIGS. 8A and 8B are diagrams showing an example of the hardware configuration of the occupant detection device according to the first embodiment. FIG. 14 is a diagram showing an example of the configuration of an occupant detection device according to a second embodiment. FIG. 15 is a diagram for explaining an image of the process of detecting the presence or absence of an occupant in the vehicle by the occupant detection unit in the second embodiment. FIG. 16 is a flowchart for explaining the operation of the occupant detection device according to the second embodiment. FIG. 17 is a flowchart for explaining details of the occupant detection process by the occupant detection unit in step ST5a of FIG. 11. FIG. 18 is a diagram showing an example of the configuration of an occupant detection device according to a third embodiment. FIG. 19 is a diagram for explaining an image of the process of determining whether occupant detection can be performed by the occupant detection execution determination unit in the third embodiment. FIG. 19 is a flowchart for explaining the operation of the occupant detection device according to the third embodiment.16 is a flowchart for explaining details of the occupant detection execution possibility determination process by the occupant detection execution determination unit in step ST500 of FIG. 15.

[0009] In the present disclosure, an occupant detection device detects the presence or absence of an occupant for each target seat in the interior of a mobile body, taking into account vibrations of the target seat, based on information (hereinafter referred to as "sensor information") indicating a phase change in a reflected wave of radio waves emitted by a radio wave sensor toward a target seat area set for each target seat (hereinafter referred to as a "target seat") for detecting the presence or absence of an occupant, reflected by an object (hereinafter referred to as a "reflecting object") within the target seat area, and vibration information of the main body of the mobile body acquired by a vibration acquisition device that acquires information regarding vibrations of the main body of the mobile body (hereinafter referred to as "vibration information"). In the first embodiment, the target seat area is an area set for each target seat and includes the target seat. Specifically, including the target seat refers to an area above the seat surface of the target seat and in front of the backrest of the target seat, including the headrest. The occupant detection device acquires sensor information from the radio wave sensor for each target seat, more specifically, for each target seat area.

[0010] The radio wave sensor is a general radio wave sensor that detects objects, such as a millimeter-wave radar. The radio wave sensor emits radio waves toward each target seat area and receives the radio waves (reflected waves) that are reflected by the surface of a reflective object present in each target seat area. The radio wave sensor outputs sensor information indicating a phase change of the reflected waves to an occupant detection device. Here, the reflective object may include the occupant and the target seat. When vibration occurs in the moving object, the sensor information indicating the phase change of the reflected waves may include a vibration component due to the movement of the occupant as well as a vibration component due to each target seat.

[0011] The vibration acquisition device is, for example, an acceleration sensor. One vibration acquisition device is provided on the moving body. The vibration acquisition device detects the shaking of the moving body itself, in other words, vibration.

[0012] As described above, when vibration occurs in a moving object, the sensor information indicating the phase change of the reflected wave may contain vibration components of each target seat in addition to vibration components due to the movement of the occupant. The occupant detection device according to the first embodiment calculates the vibration of each target seat based on the vibration information acquired from the vibration acquisition device, and detects the presence or absence of an occupant from the sensor information acquired from the radio wave sensor, taking into account the calculated vibration of each target seat. In the first embodiment, the occupant detection device detects the presence or absence of an occupant based on the sensor information and the vibration information, by removing the vibration components of each target seat from the vibration components included in the sensor information (in other words, vibration noise that becomes a noise component in occupant detection). This allows the occupant detection device to detect the presence or absence of an occupant while taking into account the vibration of each target seat. Details of the occupant detection device will be described later.

[0013] In the following first embodiment, as an example, it is assumed that the occupant of the moving body detected by the occupant detection device is an occupant of a vehicle, and as an example, the vibration acquisition device is an acceleration sensor.

[0014] FIG. 1 is a diagram illustrating an example of the physical configuration of an occupant detection device 300, a radio wave sensor 100, and a vibration acquisition device 200 according to the first embodiment. Note that FIG. 1 is a side view of the interior of a vehicle, and for convenience, FIG. 1 only illustrates the occupant detection device 300, the radio wave sensor 100, the vibration acquisition device 200, a target seat, and an occupant seated in the target seat. In FIG. 1, a vehicle is indicated by "C." The occupant detection device 300, the radio wave sensor 100, and the vibration acquisition device 200 are provided in the vehicle cabin. The radio wave sensor 100 and the vibration acquisition device 200 are provided in the vehicle cabin, for example, near the overhead console. One radio wave sensor 100 and one vibration acquisition device 200 are provided in the vehicle cabin. The occupant detection device 300 is provided in the vehicle cabin, for example, on the dashboard. The installation positions of the radio wave sensor 100, the vibration acquisition device 200, and the occupant detection device 300 shown in FIG. 1 are merely examples, and the radio wave sensor 100, the vibration acquisition device 200, and the occupant detection device 300 may be installed at positions other than those shown in FIG. 1 . The radio wave sensor 100 is installed so as to emit radio waves to each seat target area in the vehicle cabin and acquire reflected waves of the radio waves reflected by objects in each seat target area. The vibration acquisition device 200 is installed so as to acquire vibration information related to vibrations of the vehicle body. The occupant detection device 300 is installed at an appropriate position in the vehicle cabin.

[0015] FIG. 2 is a diagram illustrating an example of the configuration of an occupant detection device 300 according to the first embodiment. As illustrated in FIG. 2, the occupant detection device 300 is connected to a radio wave sensor 100 and a vibration acquisition device 200. Based on the sensor information acquired from the radio wave sensor 100 and the vibration information acquired from the vibration acquisition device 200, the occupant detection device 300 detects the presence or absence of an occupant by removing the vibration components of each target seat from the vibration components included in the sensor information (in other words, vibration noise that becomes a noise component in occupant detection). In the first embodiment, when the occupant detection device 300 detects the presence of an occupant, it also determines the type of occupant. In the first embodiment, the type of occupant is either an adult or a child.

[0016] As described above, in the first embodiment, the vibration acquisition device 200 is assumed to be an acceleration sensor. Hereinafter, the vibration acquisition device 200 will be described as an acceleration sensor. Also, hereinafter, the occupant detection device 300 according to the first embodiment will be described assuming that vibrations are occurring in a vehicle. In the first embodiment, it is assumed that the vibrations occurring in a vehicle are relatively small and continuous vibrations caused, for example, by the vehicle idling or vibrations caused by a rough road. In the first embodiment, the occupant detection device 300 detects the presence or absence of an occupant by taking into account the vibrations of each target seat when such relatively small and continuous vibrations are occurring. More specifically, in the first embodiment, the occupant detection device 300 detects the presence or absence of an occupant by removing the vibration components of each target seat from the vibration components calculated based on the sensor information. The occupant detection device 300 calculates the vibration components of each seat from the vibration components of the vehicle itself based on the vibration information, and then subtracts (i.e., subtracts) the calculated vibration components of each seat from the vibration components of the reflecting object calculated based on the sensor information, thereby eliminating the vibration noise.

[0017] The occupant detection device 300 includes a radio wave information acquisition unit 301, an occupant candidate vibration displacement calculation unit 302, an acceleration information acquisition unit 303, a moving body vibration displacement calculation unit 304, a seat vibration displacement calculation unit 305, and an occupant detection unit 307. The occupant detection unit 307 includes a noise removal unit 306.

[0018] The radio wave information acquisition unit 301 acquires sensor information indicating a time change in the phase of a reflected wave from each target seat area from the radio wave sensor 100. More specifically, the radio wave information acquisition unit 301 acquires sensor information indicating a time change in the phase of a reflected wave reflected by a reflecting object in each target seat area from the radio wave sensor 100. The radio wave information acquisition unit 301 outputs the acquired sensor information to the occupant candidate vibration displacement calculation unit 302.

[0019] The occupant candidate vibration displacement calculation unit 302 calculates, for each target seat, the magnitude of vibration of a reflecting object that is the source of the reflected wave, i.e., the time change of the vibration displacement, based on the sensor information output from the radio wave information acquisition unit 301. The reflecting object includes an occupant and the target seat. In the first embodiment, the vibration displacement of the reflecting object calculated by the occupant candidate vibration displacement calculation unit 302 is also referred to as the "occupant candidate vibration displacement." The occupant candidate vibration displacement calculation unit 302 calculates the time change of the occupant candidate vibration displacement using a time waveform or a frequency spectrum.

[0020] Generally, there is a correlation between the phase change of a reflected wave of a radio wave and the magnitude of vibration (i.e., vibration displacement) of the object that is the source of the reflection (i.e., the reflecting object). The occupant candidate vibration displacement calculation unit 302 calculates the time change of the occupant candidate vibration displacement in each target seat using a correlation function between the time change of the phase of the reflected wave and the vibration displacement. It is assumed that the correlation function is set in advance by an administrator or the like.

[0021] The occupant candidate vibration displacement calculation unit 302 outputs information indicating the time change of the occupant candidate vibration displacement at the target seat calculated for each target seat (hereinafter referred to as ``occupant candidate vibration displacement information'') to the occupant detection unit 307.

[0022] The acceleration information acquisition unit 303 acquires, as vibration information, information indicating the change in acceleration of the vehicle itself over time (hereinafter referred to as "acceleration information") from the acceleration sensor, which is the basis for calculating the magnitude of vibration of the vehicle itself (i.e., vibration displacement). The acceleration information is information indicating the change in acceleration of the vehicle itself over time for each coordinate axis (x-axis, y-axis, z-axis) of the acceleration sensor. Note that the calculation of the vibration displacement of the vehicle itself is performed by the moving body vibration displacement calculation unit 304. The acceleration information acquisition unit 303 outputs the acquired acceleration information to the moving body vibration displacement calculation unit 304.

[0023] The moving body vibration displacement calculation unit 304 calculates the time change of the vibration displacement of the vehicle itself from the time change of the acceleration of the vehicle itself based on the acceleration information output from the acceleration information acquisition unit 303. The time change of the acceleration of the vehicle itself and the vibration displacement of the vehicle itself are the time change of acceleration and the vibration displacement for each coordinate axis of the acceleration sensor, respectively. Note that the vibration displacement of the vehicle itself means the vibration displacement of the main body of the vehicle. In the first embodiment, the vibration displacement of the vehicle itself for each coordinate axis of the acceleration sensor calculated by the moving body vibration displacement calculation unit 304 is also referred to as "vehicle vibration displacement." The moving body vibration displacement calculation unit 304 calculates the time change of the vehicle vibration displacement using a time waveform or a frequency spectrum.

[0024] The moving body vibration displacement calculation unit 304 may calculate the vehicle vibration displacement using a common calculation method. One common calculation method is a method of performing double integration using the acceleration value and the sampling period. The moving body vibration displacement calculation unit 304 may, for example, calculate the instantaneous value of the velocity using the following (Equation 1), and then calculate the vehicle vibration displacement using the following (Equation 2): (Instantaneous value of velocity) = Σ (Instantaneous value of acceleration) × (Sampling period) ... (Equation 1) (Vehicle vibration displacement) = Σ (Instantaneous value of velocity) × (Sampling period) ... (Equation 2) Note that the influence of gravity is excluded when the moving body vibration displacement calculation unit 304 calculates the vehicle vibration displacement as described above.

[0025] After calculating the time change of the vehicle vibration displacement, the moving body vibration displacement calculation unit 304 outputs information indicating the time change of the vehicle vibration displacement (hereinafter referred to as "vehicle vibration displacement information") to the seat vibration displacement calculation unit 305. The vehicle vibration displacement information is information indicating the time change of the vehicle vibration displacement for each coordinate axis of the acceleration sensor.

[0026] The seat vibration displacement calculation unit 305 calculates, for each target seat, a time change in vibration displacement on an axis pointing from the radio wave sensor 100 toward the target seat (hereinafter referred to as the "radio wave sensor axis") based on the vehicle vibration displacement information output from the moving body vibration displacement calculation unit 304. The axis pointing from the radio wave sensor 100 toward the target seat is the direction of the reflected wave from the target seat area of ​​the radio wave sensor 100, and is the vibration direction of the candidate occupant vibration displacement. In the first embodiment, the vibration displacement on the radio wave sensor axis calculated by the seat vibration displacement calculation unit 305 based on the vehicle vibration displacement information is also referred to as the "seat vibration displacement." The seat vibration displacement calculation unit 305 calculates the time change in seat vibration displacement using a time waveform or a frequency spectrum.

[0027] Here, the calculation of the time change in seat vibration displacement of the target seat by the seat vibration displacement calculation unit 305 will be described in more detail using the drawings. FIG. 3 is a diagram for explaining an example of a method in which the seat vibration displacement calculation unit 305 calculates the time change in seat vibration displacement of the target seat in the first embodiment. FIG. 3A is a diagram showing an example of the state of the interior of the vehicle, and is a diagram for explaining the relationship between the coordinate axis of the acceleration sensor (i.e., the vibration acquisition device 200) and the radio wave sensor axis. Note that FIG. 3A is a diagram showing the interior of the vehicle from the side, and in FIG. 3A, only the radio wave sensor 100, the acceleration sensor, the target seat, and the occupant seated in the target seat are shown. In FIG. 3A, the target seat in the front row is indicated by "S1" and the target seat in the rear row is indicated by "S2". In addition, in FIG. 3A, the coordinate axis of the acceleration sensor is indicated by "A1". In addition, in FIG. 3A, the radio wave sensor axis is indicated by "A2". Note that for convenience, in FIG. 3A, only the radio wave sensor axis corresponding to the target seat in the front row is shown. 3B is a diagram showing an example of the components of the unit vector in the x' direction of the radio wave sensor axis pointing to each seat direction in a coordinate system based on the coordinate axes of the acceleration sensor, and the unit vectors in the y' and z' directions of new coordinate axes perpendicular to the x' direction. Fig. 3C is a diagram showing an example of a general formula for basis vector conversion used when the seat vibration displacement calculation unit 305 calculates the seat vibration displacement.

[0028] As shown in FIG. 3A , the coordinate axes of the acceleration sensor and the radio wave sensor axes are different. Therefore, in order to subtract the time change in seat vibration displacement from the time change in occupant candidate vibration displacement in order to remove vibration noise, the occupant candidate vibration displacement and the seat vibration displacement must be values ​​on the same axis. Note that the subtraction of the time change in seat vibration displacement from the time change in occupant candidate vibration displacement is performed by the noise removal unit 306 of the occupant detection unit 307. Therefore, the seat vibration displacement calculation unit 305 calculates the time change in seat vibration displacement as a value on the radio wave sensor axis based on the vehicle vibration displacement information. More specifically, the seat vibration displacement calculation unit 305 calculates the time change in vehicle vibration displacement on the radio wave sensor axis as the time change in seat vibration displacement for each target seat.

[0029] For example, the seat vibration displacement calculation unit 305 uses basis vector transformation to calculate the time change in vehicle vibration displacement on the radio wave sensor axis for each target seat. Specifically, the seat vibration displacement calculation unit 305 uses a general formula for basis vector transformation (see FIG. 3C ) to calculate the displacement of the vehicle vibration displacement in the radio wave sensor axis x' direction in a coordinate system based on the coordinate axes of the acceleration sensor. The seat vibration displacement calculation unit 305 calculates the displacement in the radio wave sensor axis x' direction for all vehicle vibration displacements that change over time. Note that, for example, an administrator or the like has previously determined the components of the unit vector in the radio wave sensor axis x' direction pointing toward each seat in the coordinate system based on the coordinate axes of the acceleration sensor, as well as the unit vectors in new coordinate axes y' and z' directions that are perpendicular to the unit vector, as shown in FIG. 3B . Information indicating the components of the unit vectors determined by the administrator or the like is stored in the seat vibration displacement calculation unit 305. The seat vibration displacement calculation unit 305 substitutes the information indicating the components of the unit vector it holds into a general formula for the basis vector to find the displacement in the x' direction of the radio wave sensor axis.

[0030] Next, the seat vibration displacement calculation unit 305 scales the calculated displacement value in the x' direction of the radio wave sensor axis to the actual magnitude of seat vibration. The magnitude of the vibration (vibration) acquired by the acceleration sensor and the actual magnitude of the seat vibration (vibration) have different scales of values ​​indicating the magnitude of the vibration (vibration). Therefore, the seat vibration displacement calculation unit 305 performs the scaling. For example, the seat vibration displacement calculation unit 305 performs the scaling using a preset correlation function, and the time change in the displacement after the scaling is determined as the time change in the seat vibration displacement. An administrator or the like sets a correlation function for performing the scaling for each target seat in advance, and stores the correlation function in the seat vibration displacement calculation unit 305.

[0031] In this way, the seat vibration displacement calculation unit 305 calculates the time change of the seat vibration displacement. Note that the above-described method of calculating the time change of the seat vibration displacement by the seat vibration displacement calculation unit 305 is merely an example. For example, when performing base vector transformation, the seat vibration displacement calculation unit 305 may calculate the time change of the seat vibration displacement by rotating the coordinate system using the angle difference between the coordinate axis of the acceleration sensor and the axis of the radio wave sensor corresponding to each target seat, rather than using the components of the new coordinate axis. The seat vibration displacement calculation unit 305 can calculate the time change of the seat vibration displacement by performing various vector transformations on the time change of the vehicle vibration displacement.

[0032] After calculating the change in seat vibration displacement over time for each target seat, the seat vibration displacement calculation unit 305 outputs information indicating the change in seat vibration displacement over time for each target seat (hereinafter referred to as ``seat vibration displacement information'') to the occupant detection unit 307.

[0033] The occupant detection unit 307 detects the presence or absence of an occupant in the vehicle, taking into consideration the vibration of each target seat, based on the time change of the occupant candidate vibration displacement calculated for each target seat by the occupant candidate vibration displacement calculation unit 302 and the time change of the seat vibration displacement of each target seat calculated by the seat vibration displacement calculation unit 305. Specifically, the occupant detection unit 307 detects the presence or absence of an occupant by subtracting the time change of the seat vibration displacement from the time change of the occupant candidate vibration displacement for each target seat, and comparing the frequency spectrum based on the time change of the occupant candidate vibration displacement after subtracting the time change of the seat vibration displacement with a preset threshold (hereinafter referred to as the "occupant detection threshold"). Details of the detection of the presence or absence of an occupant by the occupant detection unit 307 will be described below.

[0034] The noise removal unit 306 included in the occupant detection unit 307 subtracts, for each target seat, the time change in seat vibration displacement corresponding to the target seat from the time change in occupant candidate vibration displacement, based on the occupant candidate vibration displacement information output from the occupant candidate vibration displacement calculation unit 302 and the seat vibration displacement information output from the seat vibration displacement calculation unit 305. The noise removal unit 306 may perform the subtraction using either a time waveform or a frequency spectrum. If the occupant candidate vibration displacement and the seat vibration displacement are calculated using a time waveform, the noise removal unit 306 performs the subtraction using the time waveform. If the occupant candidate vibration displacement and the seat vibration displacement are calculated using a frequency spectrum, the noise removal unit 306 performs the subtraction using the frequency spectrum. The noise removal unit 306 thus subtracts the time change in seat vibration displacement from the time change in occupant candidate vibration displacement, thereby eliminating vibration noise. Hereinafter, the occupant candidate vibration displacement obtained after the noise removal unit 306 subtracts the seat vibration displacement corresponding to each target seat will be referred to as the "noise-removed occupant candidate vibration displacement." The noise removal unit 306 outputs information indicating the time change of the noise-removed occupant candidate vibration displacement at the target seat calculated for each target seat (hereinafter referred to as ``noise-removed occupant candidate vibration displacement information'') to the occupant detection unit 307.

[0035] The occupant detection unit 307 detects the presence or absence of an occupant for each target seat based on the noise-removed occupant candidate vibration displacement information output from the noise removal unit 306, using a frequency spectrum of the noise-removed occupant candidate vibration displacement during a certain period (hereinafter referred to as an "occupant detection period"). The occupant detection period is set appropriately in advance by, for example, an administrator or the like. Specifically, the occupant detection unit 307 detects the presence or absence of an occupant by comparing a power component of a human breathing frequency band in the frequency spectrum of the noise-removed occupant candidate vibration displacement during the occupant detection period with an occupant detection threshold. The occupant detection threshold is set appropriately in advance by an administrator or the like. The administrator or the like sets a value that is assumed to be capable of detecting a power component of a human breathing frequency band as the occupant detection threshold. For example, the occupant detection unit 307 detects that an occupant is present if the power component in the frequency band of human breathing in the frequency spectrum of the noise-removed occupant candidate vibration displacement during the occupant detection period is greater than or equal to the occupant detection threshold, and detects that an occupant is not present if the power component is less than the occupant detection threshold.

[0036] FIG. 4 is a diagram illustrating an example of the process of detecting the presence or absence of a vehicle occupant performed by the occupant detection unit 307 in the first embodiment. FIG. 4A is a diagram illustrating an example of subtraction of a time change in seat vibration displacement from a time change in occupant candidate vibration displacement performed by the noise removal unit 306. FIG. 4B is a diagram illustrating another example of subtraction of a time change in seat vibration displacement from a time change in occupant candidate vibration displacement performed by the noise removal unit 306. FIG. 4A illustrates an example of subtraction when the time change in occupant candidate vibration displacement and the time change in seat vibration displacement are shown as time waveforms, and FIG. 4B illustrates an example of subtraction when the time change in occupant candidate vibration displacement and the time change in seat vibration displacement are shown as frequency spectra. FIG. 4B also illustrates an example of comparison, performed by the occupant detection unit 307, between a power component in the frequency band of human breathing in the frequency spectrum of the noise-removed occupant candidate vibration displacement during the occupant detection period and an occupant detection threshold (denoted as a "detection threshold" in FIG. 4B ).

[0037] First, the subtraction by the noise removal unit 306 will be described when the occupant candidate vibration displacement and the seat vibration displacement are shown as time waveforms. For example, if an occupant is currently present, it is assumed that the vibration indicated by the occupant candidate vibration displacement before the subtraction by the noise removal unit 306 is a vibration due to the occupant's breathing or the like superimposed with the vibration of the target seat (see "401" in FIG. 4A). In this case, the noise removal unit 306 subtracts the time change of the seat vibration displacement from the time change of the occupant candidate vibration displacement, so that the noise-removed occupant candidate vibration displacement indicates the vibration after the vibration of the target seat has been removed from the vibration indicated by the occupant candidate vibration displacement before the subtraction (see "402" in FIG. 4A).

[0038] On the other hand, if there is no occupant present, for example, the occupant candidate vibration displacement before subtraction by the noise removal unit 306 is assumed to indicate vibration of the target seat caused by vibration of the vehicle itself transmitted to the target seat, and does not include vibration caused by the occupant's breathing, etc. (see "403" in FIG. 4A). In this case, the noise removal unit 306 subtracts the time change in the seat vibration displacement from the time change in the occupant candidate vibration displacement, so that the noise-removed occupant candidate vibration displacement becomes zero (see "404" in FIG. 4A). Note that in the first embodiment, "zero" includes the term "approximately zero."

[0039] Next, the subtraction performed by the noise removal unit 306 when the occupant candidate vibration displacement and the seat vibration displacement are represented by a frequency spectrum will be described. For example, assuming that an occupant is currently present, it is assumed that the power components in the occupant candidate vibration displacement before subtraction by the noise removal unit 306 include power components in the frequency band of the occupant's breathing, etc., and power components in the frequency band of the vibration of the target seat (see "411" in FIG. 4B). For ease of understanding, it is assumed here that the frequency band of the vibration of the target seat is a range similar to the frequency band of human breathing. In this case, by the noise removal unit 306 subtracting the time change of the seat vibration displacement from the time change of the occupant candidate vibration displacement, the power components in the noise-removed occupant candidate vibration displacement represent power components obtained after the power components due to the vibration of the target seat have been removed from the power components of the occupant candidate vibration displacement before subtraction (see "412" in FIG. 4B).

[0040] On the other hand, if there is no occupant present, for example, it is assumed that the power component in the occupant candidate vibration displacement before subtraction by the noise removal unit 306 does not include a power component in the frequency band of the occupant's breathing, etc., but indicates a power component in the frequency band of the vibration of the target seat caused by the vibration of the vehicle itself being transmitted to the target seat (see "413" in FIG. 4B). In this case, the noise removal unit 306 subtracts the time change in the seat vibration displacement from the time change in the occupant candidate vibration displacement, so that the noise-removed occupant candidate vibration displacement becomes zero (see "414" in FIG. 4B).

[0041] After the noise removal unit 306 performs the subtraction as described above, the occupant detection unit 307 then compares the power component of the frequency band of human breathing in the frequency spectrum of the noise-removed occupant candidate vibration displacement during the occupant detection period with the occupant detection threshold. At this time, if the noise-removed occupant candidate vibration displacement is represented as a time waveform, the occupant detection unit 307 converts the time waveform of the noise-removed occupant candidate vibration displacement into a frequency spectrum. In other words, the occupant detection unit 307 uses the frequency spectrum when detecting the presence or absence of an occupant.

[0042] For example, if an occupant is currently present, even if the seat vibration displacement is subtracted from the occupant candidate vibration displacement, only the component due to the vibration of the target seat is subtracted, and therefore the power component of the frequency band of human breathing in the frequency spectrum of the noise-removed occupant candidate vibration displacement is equal to or greater than the occupant detection threshold. In other words, the power component of the frequency band of human breathing in the frequency spectrum of the noise-removed occupant candidate vibration displacement is the power component of the frequency spectrum of only human vibration, and the occupant detection unit 307 can detect the presence of an occupant because the power component of the human breathing frequency band is equal to or greater than the occupant detection threshold (see "Occupant Present" in FIG. 4B).

[0043] On the other hand, for example, if an occupant is not currently present, the power component of the frequency band of human breathing in the frequency spectrum of the occupant candidate vibration displacement before the noise removal unit 306 performs the subtraction is the same as the power component of the frequency band of human breathing in the frequency spectrum of the seat vibration displacement. Therefore, if the power component is compared with the occupant detection threshold as is, the power component may exceed the occupant detection threshold, and the occupant detection unit 307 may detect the presence of an occupant even though no occupant is present. However, in the first embodiment, the occupant detection unit 307 compares the power component of the frequency band of human breathing in the frequency spectrum of the noise-removed occupant candidate vibration displacement with the occupant detection threshold. As a result, the occupant detection unit 307 compares the power component of the frequency spectrum of only the occupant vibration with the occupant detection threshold. When there is no occupant vibration, the occupant detection unit 307 can determine that the power component of the frequency band of human breathing is below the occupant detection threshold because the power component of the frequency spectrum of only the occupant vibration is zero. That is, the occupant detection unit 307 detects that there is no occupant (see "No occupant" in FIG. 4B). In this way, the occupant detection unit 307 can prevent erroneous detection that there is an occupant when there is no occupant.

[0044] In the above-described detection of the presence or absence of an occupant by the occupant detection unit 307, the value based on the power component to be compared with the occupant detection threshold may be any of the following values: the power average value, the power median value, the power maximum value, a power value corresponding to a certain percentile, or the mode value of the frequency spectrum. It is sufficient that the occupant detection threshold and the value based on the power component to be compared with the occupant detection threshold are of the same type of value.

[0045] When the occupant detection unit 307 detects the presence of an occupant, it subsequently determines the type of the detected occupant, in other words, whether the occupant is an adult or a child. The occupant detection unit 307 determines the type of each detected occupant.

[0046] Specifically, the occupant detection unit 307 determines the type of occupant based on the number of vibrations, i.e., the frequency band, of the noise-removed occupant candidate vibration displacement corresponding to the target seat detected as having an occupant. If the frequency band of the noise-removed occupant candidate vibration displacement during the occupant detection period is within a predetermined range (hereinafter referred to as the "first range"), the occupant detection unit 307 determines that the occupant is a child. If the frequency band of the noise-removed occupant candidate vibration displacement during the occupant detection period is within a predetermined range (hereinafter referred to as the "second range"), the occupant detection unit 307 determines that the occupant is an adult. The first and second ranges are each set in advance by an administrator or the like and stored in a location accessible by the occupant detection unit 307. It is assumed that the first and second ranges are different ranges. It is generally assumed that the respiratory rate in a given period decreases as a person gets older. Therefore, the administrator or the like sets the first range and the second range so that the second range is a lower frequency band range than the first range, for example.

[0047] In the first embodiment, the process performed by the occupant detection unit 307 to detect the presence or absence of an occupant in the vehicle and determine the type of occupant when it detects that an occupant is present is referred to as "occupant detection process." After performing the occupant detection process as described above, the occupant detection unit 307 further controls the output of an alarm to an alarm device. In the first embodiment, the process of controlling the output of an alarm performed by the occupant detection unit 307 is referred to as "alarm output control process."

[0048] In the warning output control process, if the result of the occupant detection process indicates that there is an occupant in the vehicle and that the occupant is only a child, the occupant detection unit 307 outputs information (hereinafter referred to as "warning output control information") to the warning device to cause the occupant to output a warning. When the warning output control information is output, the warning device outputs a warning based on the warning output control information. The warning device is, for example, a device such as a speaker, a display, or a smartphone. The warning output method by the warning device may be, for example, audio output or video display, or a combination of these. The warning device may be provided in the vehicle or outside the vehicle. In this way, the occupant detection device 300 can notify people in the vicinity of the vehicle that a child has been left behind in the vehicle.

[0049] The operation of the occupant detection device 300 according to the first embodiment will now be described. Fig. 5 is a flowchart for explaining the operation of the occupant detection device 300 according to the first embodiment. The occupant detection device 300 starts the operation shown in the flowchart of Fig. 5 when, for example, the power supply to the occupant detection device 300 is turned on, which is a trigger. The occupant detection device 300 repeats the operation shown in the flowchart of Fig. 5 until, for example, the power supply is no longer turned on.

[0050] The radio wave information acquisition unit 301 acquires, from the radio wave sensor 100, sensor information indicating a time change in the phase of the reflected wave from each target seat area, and outputs the acquired sensor information to the occupant candidate vibration displacement calculation unit 302. Thereafter, the occupant candidate vibration displacement calculation unit 302 calculates a time change in the occupant candidate vibration displacement for each target seat based on the sensor information output from the radio wave information acquisition unit 301 (step ST1). The occupant candidate vibration displacement calculation unit 302 outputs, to the occupant detection unit 307, occupant candidate vibration displacement information indicating a time change in the occupant candidate vibration displacement at the target seat calculated for each target seat.

[0051] The acceleration information acquisition unit 303 acquires, as vibration information, acceleration information indicating a change in the acceleration of the vehicle itself over time for each coordinate axis (x-axis, y-axis, z-axis) of the acceleration sensor (step ST2). The acceleration information acquisition unit 303 outputs the acquired acceleration information to the moving body vibration displacement calculation unit 304.

[0052] The moving body vibration displacement calculation unit 304 calculates a time change in vehicle vibration displacement from a time change in the acceleration of the vehicle itself based on the acceleration information output from the acceleration information acquisition unit 303 in step ST2 (step ST3). The moving body vibration displacement calculation unit 304 outputs vehicle vibration displacement information indicating a time change in vehicle vibration displacement to the seat vibration displacement calculation unit 305.

[0053] The seat vibration displacement calculation unit 305 calculates the change in seat vibration displacement over time for each target seat based on the vehicle vibration displacement information output from the moving body vibration displacement calculation unit 304 in step ST3 (step ST4). The seat vibration displacement calculation unit 305 outputs seat vibration displacement information indicating the change in seat vibration displacement over time for each target seat to the occupant detection unit 307.

[0054] The occupant detection unit 307 detects the presence or absence of an occupant in the vehicle based on the time change in the occupant candidate vibration displacement calculated for each target seat by the occupant candidate vibration displacement calculation unit 302 and the time change in the seat vibration displacement of each target seat calculated by the seat vibration displacement calculation unit 305, taking into account the vibration of each target seat, and performs occupant detection processing to determine the type of occupant if it detects that an occupant is present (step ST5).

[0055] After performing the occupant detection process in step ST5, the occupant detection unit 307 performs an alarm output control process to control the alarm device to output an alarm (step ST6).

[0056] 5, the process of step ST1 and the processes of steps ST2 to ST4 are performed in parallel, but this is merely an example. For example, the process of step ST1 may be performed first, followed by the processes of steps ST2 to ST4, or vice versa. It is sufficient that the process of step ST1 and the processes of steps ST2 to ST4 are performed before the process of step ST5 is performed.

[0057] FIG. 6 is a flowchart for explaining details of the occupant detection process by the occupant detection unit 307 in step ST5 of FIG.

[0058] The noise removal unit 306 subtracts the time change of the seat vibration displacement corresponding to the target seat from the time change of the occupant candidate vibration displacement for each target seat based on the occupant candidate vibration displacement information output from the occupant candidate vibration displacement calculation unit 302 and the seat vibration displacement information output from the seat vibration displacement calculation unit 305, and calculates the time change of the noise-removed occupant candidate vibration displacement (step ST101). The noise removal unit 306 outputs the noise-removed occupant candidate vibration displacement information to the occupant detection unit 307.

[0059] Based on the noise-removed occupant candidate vibration displacement information output from the noise removal unit 306, the occupant detection unit 307 determines, for each target seat, whether the power component in the human breathing frequency band in the frequency spectrum of the noise-removed occupant candidate vibration displacement during the occupant detection period is greater than or equal to the occupant detection threshold (step ST102).

[0060] In step ST102, if the power component in the frequency band of human breathing in the frequency spectrum of the noise-removed occupant candidate vibration displacement during the occupant detection period is equal to or greater than the occupant detection threshold (if "YES" in step ST102), the occupant detection unit 307 detects the presence of an occupant (step ST103).The occupant detection unit 307 then determines the range of the frequency band during the occupant detection period of the noise-removed occupant candidate vibration displacement corresponding to the target seat detected as having an occupant (step ST105).

[0061] In step ST105, as a result of determining which range of the frequency band of the noise-removed occupant candidate vibration displacement corresponding to the target seat detected as having an occupant falls within the first range (in the case of "YES" in step ST106), the occupant detection unit 307 determines that the occupant detected as having an occupant in step ST103 is a child (step ST107). Then, the occupant detection unit 307 ends the processing shown in the flowchart of FIG. 6.

[0062] In step ST105, the occupant detection unit 307 determines the frequency band of the noise-removed occupant candidate vibration displacement corresponding to the target seat detected as having an occupant in the occupant detection period as a result of determining that the frequency band is within the second range ("NO" in step ST106 and "YES" in step ST108), and determines that the occupant detected as having an occupant in step ST103 is an adult (step ST109). The occupant detection unit 307 then terminates the processing shown in the flowchart of FIG. 6. Furthermore, in the case where the occupant detection unit 307 determines the frequency band of the noise-removed occupant candidate vibration displacement corresponding to the target seat detected as having an occupant in the occupant detection period as a result of determining that the frequency band is neither within the first range nor the second range ("NO" in step ST108), the occupant detection unit 307 terminates the processing shown in the flowchart of FIG. 6.

[0063] On the other hand, in step ST102, if the power component in the frequency band of human breathing in the frequency spectrum of the noise-removed occupant candidate vibration displacement during the occupant detection period is less than the occupant detection threshold (if "NO" in step ST102), the occupant detection unit 307 detects that there is no occupant (step ST104).Then, the occupant detection unit 307 ends the process shown in the flowchart of FIG.

[0064] FIG. 7 is a flowchart for explaining details of the warning output control process by the occupant detection unit 307 in step ST6 of FIG.

[0065] As a result of the occupant detection process, the occupant detection unit 307 determines whether there is an occupant in the vehicle and the occupant is only a child (step ST111). If the result of the occupant detection process in step ST111 indicates that there is an occupant in the vehicle and the occupant is only a child ("YES" in step ST111), the occupant detection unit 307 outputs warning output control information to the warning device (step ST112).

[0066] In step ST111, if the occupant detection process detects that there are no occupants in the vehicle, or if the detected occupants include adults ("NO" in step ST111), the occupant detection unit 307 does not output alarm output control information to the alarm device, and terminates the process shown in the flowchart of Figure 7.

[0067] In this way, the occupant detection device 300 calculates the time change in vibration displacement of the reflecting object (occupant candidate vibration displacement) for each target seat based on sensor information indicating the phase change of the reflected wave, which is the result of the radio wave emitted by the radio wave sensor 100 toward the target seat area set for each target seat in the vehicle cabin and reflected by the reflecting object in each target seat area. The occupant detection device 300 also calculates the time change in the vehicle vibration displacement (vehicle vibration displacement) based on the vibration information acquired by the vibration acquisition device 200 installed in the vehicle, and calculates the time change in the vibration displacement of the target seat (seat vibration displacement) for each target seat based on the calculated time change in the vehicle vibration displacement. The occupant detection device 300 then detects the presence or absence of an occupant in the vehicle based on the time change in the occupant candidate vibration displacement and the time change in the seat vibration displacement, taking into account the vibration of each target seat. Therefore, the occupant detection device 300 can improve the accuracy of occupant detection in the vehicle by taking into account the vibration of the target seat.

[0068] More specifically, in the first embodiment, the occupant detection unit 307 in the occupant detection device 300 calculates, for each target seat, a time change in a noise-removed occupant candidate vibration displacement, which is the time change in the occupant candidate vibration displacement obtained by subtracting the time change in the vibration displacement of the target seat (seat vibration displacement) from the time change in the vibration displacement of the reflecting object (occupant candidate vibration displacement), and detects the presence or absence of an occupant by comparing the power component of the frequency band of human breathing in the frequency spectrum based on the calculated time change in the noise-removed occupant candidate vibration displacement with an occupant detection threshold value. Therefore, the occupant detection device 300 can improve the accuracy of occupant detection in a vehicle by taking into account the vibration of the target seat.

[0069] If a vehicle is equipped with a sensor such as an accelerometer for detecting the vibration of each target seat, and the occupant detection device 300 acquires information indicating the time change in the vibration displacement of each target seat from the sensor for each target seat when calculating the time change in the seat vibration displacement of each target seat, the process of calculating the vibration component of each target seat from the vibration component of the vehicle itself can be omitted. However, this method requires the installation of a sensor such as an accelerometer for each target seat, which poses a problem of increased installation costs for sensors such as accelerometers for each target seat. In contrast, the occupant detection device 300 according to the first embodiment calculates the time change in the vibration displacement of each target seat (seat vibration displacement) from the time change in the vibration displacement of the vehicle (vehicle vibration displacement) to improve the accuracy of occupant detection by taking into account the vibration of each target seat. In other words, the occupant detection device 300 can perform occupant detection taking into account the vibration of each target seat from the vibration information obtained from the vibration acquisition device 200 installed in the vehicle. Therefore, the occupant detection device 300 can contribute to reducing the cost of a system for detecting the presence or absence of an occupant in a vehicle.

[0070] 8A and 8B are diagrams illustrating an example of a hardware configuration of an occupant detection device 300 according to Embodiment 1. In Embodiment 1, the functions of the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307, and the noise removal unit 306 are realized by a processing circuit 101. That is, the occupant detection device 300 includes the processing circuit 101 for performing control to detect the presence or absence of an occupant in consideration of the vibration of the target seat. The processing circuit 101 may be dedicated hardware as shown in FIG. 8A or a processor 104 that executes a program stored in a memory as shown in FIG. 8B.

[0071] When processing circuitry 101 is dedicated hardware, processing circuitry 101 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.

[0072] When the processing circuit is the processor 104, the functions of the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307, and the noise removal unit 306 are realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 105. The processor 104 reads and executes the program stored in the memory 105 to perform the functions of the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307, and the noise removal unit 306. That is, the occupant detection device 300 includes the memory 105 for storing a program that, when executed by the processor 104, results in the processing of steps ST1 to ST6 of FIG. 5 being executed. In addition, the program stored in memory 105 can also be said to cause the computer to execute the processing procedures or methods of the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307, and the noise removal unit 306. Here, the memory 105 may be, for example, a non-volatile or volatile semiconductor memory such as a RAM, a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (Electrically Erasable Programmable Read-Only Memory), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc).

[0073] Note that the functions of the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307, and the noise removal unit 306 may be partially implemented by dedicated hardware and partially implemented by software or firmware. For example, the functions of the radio wave information acquisition unit 301 and the acceleration information acquisition unit 303 may be implemented by the processing circuit 101 as dedicated hardware, and the functions of the occupant candidate vibration displacement calculation unit 302, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307, and the noise removal unit 306 may be implemented by the processor 104 reading and executing programs stored in the memory 105. The occupant detection device 300 also includes an input interface device 102 and an output interface device 103 that perform wired or wireless communication with devices such as the radio wave sensor 100 or the vibration acquisition device 200.

[0074] In the above-described first embodiment, it is assumed that the vibration acquiring device 200 is an acceleration sensor. However, this is merely an example. The vibration acquiring device 200 may be, for example, a vibration sensor. In this case, the occupant detection device 300 can acquire vehicle vibration displacement information directly from the vibration sensor. The occupant detection device 300 may acquire vehicle vibration displacement information as vibration information from the vibration sensor. In this case, the occupant detection device 300 may be configured without including the acceleration information acquiring unit 303. Furthermore, the occupant detection device 300 may omit the processing of step ST2 in the operation described using the flowchart of FIG. 5 .

[0075] In the first embodiment, the occupant detection unit 307 in the occupant detection device 300 has the function of determining the type of occupant in the occupant detection process and the function of executing the warning output control process, but this is merely an example. The function of determining the type of occupant and the function of executing the warning output control process are not essential functions for the occupant detection device 300.

[0076] In the first embodiment, the occupant detection device 300 is an in-vehicle device mounted on a vehicle, but this is merely an example. For example, some or all of the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307, and the noise removal unit 306 may be provided in a server (not shown), and the in-vehicle device and the server may constitute a system.

[0077] In the first embodiment, the occupant detection device 300 detects whether or not an occupant is present in a vehicle, but this is merely an example. The occupant detection device 300 is not limited to a vehicle, and may be configured to detect whether or not an occupant is present in a moving body other than a vehicle, such as an airplane or a train.

[0078] As described above, according to the first embodiment, the occupant detection device 300 includes an occupant candidate vibration displacement calculation unit 302 that calculates, for each target seat, a time change in the vibration displacement of a reflecting object that is a source of reflection of the reflected wave, based on sensor information that indicates a phase change of a reflected wave that is generated when the radio wave is emitted by the radio wave sensor 100 toward a target seat area including the target seat set for each target seat that is a target for detecting the presence or absence of an occupant in the cabin of the moving body and that is reflected by a reflecting object that may include the occupant and the target seat in the target seat area, and a vibration acquisition device 2 that is provided in the moving body and acquires vibration information related to the vibration of the main body of the moving body. 00, a moving body vibration displacement calculation unit 304 that calculates a time change in vibration displacement of the moving body based on the vibration information acquired by the moving body vibration displacement calculation unit 302, a seat vibration displacement calculation unit 305 that calculates a time change in vibration displacement of a target seat for each target seat based on the time change in vibration displacement of the moving body calculated by the moving body vibration displacement calculation unit 304, and an occupant detection unit 307 that detects the presence or absence of an occupant of the moving body in consideration of the vibration of each target seat based on the time change in vibration displacement of the reflecting object calculated by the occupant candidate vibration displacement calculation unit 302 and the time change in vibration displacement of each target seat calculated by the seat vibration displacement calculation unit 305. Therefore, the occupant detection device 300 can improve the accuracy of occupant detection in a moving body.

[0079] In detail, in the occupant detection device 300, the occupant detection unit 307 includes a noise removal unit 306 that calculates, for each target seat, a time change in noise-removed occupant candidate vibration displacement, which is the time change in vibration displacement of the reflecting object after subtracting the time change in vibration displacement of the target seat calculated by the seat vibration displacement calculation unit 305 from the time change in vibration displacement of the reflecting object calculated by the occupant candidate vibration displacement calculation unit 302, and detects the presence or absence of an occupant by comparing the power component of the frequency band of human breathing in the frequency spectrum based on the time change in the noise-removed occupant candidate vibration displacement calculated by the noise removal unit 306 with an occupant detection threshold. Therefore, the occupant detection device 300 can improve the accuracy of occupant detection in a moving body.

[0080] Embodiment 2. In Embodiment 1, the occupant detection device detects the presence or absence of an occupant while taking into account the vibration of each target seat by detecting the presence or absence of an occupant based on sensor information and vibration information and removing the vibration component of each target seat from the vibration component included in the sensor information. In Embodiment 2, an embodiment will be described in which the occupant detection device detects the presence or absence of an occupant while taking into account the vibration of each target seat by a method other than the method of removing the vibration component of each target seat from the vibration component included in the sensor information.

[0081] 9 is a diagram showing an example configuration of an occupant detection device 300a according to embodiment 2. In embodiment 2, the occupant detection device 300a is connected to the radio wave sensor 100 and the vibration acquisition device 200. An example physical configuration of the occupant detection device 300a, the radio wave sensor 100, and the vibration acquisition device 200 according to embodiment 2 is similar to the example physical configuration of the occupant detection device 300, the radio wave sensor 100, and the vibration acquisition device 200 according to embodiment 1 described using FIG. 1 in embodiment 1, and therefore the same reference numerals are used and redundant description will be omitted.

[0082] In the second embodiment, as in the first embodiment, the vibration acquiring device 200 is assumed to be an acceleration sensor. Hereinafter, the vibration acquiring device 200 will be described as an acceleration sensor. Also, hereinafter, the occupant detection device 300a according to the second embodiment will be described assuming that vibrations are occurring in the vehicle. In the second embodiment, as in the first embodiment, the vibrations occurring in the vehicle are assumed to be relatively small and continuous vibrations caused by, for example, vehicle idling, vibrations caused by a rough road, and the like. In the second embodiment, the occupant detection device 300a detects the presence or absence of an occupant by taking into account the vibrations of each target seat when such relatively small and continuous vibrations are occurring. More specifically, in the second embodiment, the occupant detection device 300a adjusts the occupant detection threshold based on the vibration information and detects the presence or absence of an occupant using the adjusted occupant detection threshold.

[0083] 9, components similar to those of the occupant detection device 300 described in Embodiment 1 using FIG. 2 are denoted by the same reference numerals, and redundant description will be omitted. The occupant detection device 300a according to Embodiment 2 differs from the occupant detection device 300 according to Embodiment 1 in the configuration of the occupant detection unit 307a. In Embodiment 2, the occupant detection unit 307a includes a threshold value adjustment unit 321 instead of the noise removal unit 306.

[0084] The occupant detection unit 307a detects the presence or absence of an occupant in the vehicle, taking into consideration the vibration of each target seat, based on the time change of the occupant candidate vibration displacement calculated for each target seat by the occupant candidate vibration displacement calculation unit 302 and the time change of the seat vibration displacement of each target seat calculated by the seat vibration displacement calculation unit 305. Specifically, the occupant detection unit 307a adjusts the occupant detection threshold for each target seat based on the time change of the seat vibration displacement, and detects the presence or absence of an occupant by comparing the frequency spectrum based on the time change of the occupant candidate vibration displacement with the adjusted occupant detection threshold (hereinafter referred to as the "adjusted occupant detection threshold"). Details of the detection of the presence or absence of an occupant by the occupant detection unit 307a will be described below.

[0085] The threshold adjustment unit 321 included in the occupant detection unit 307a receives seat vibration displacement information from the seat vibration displacement calculation unit 305 via the occupant detection unit 307a. The threshold adjustment unit 321 then determines whether the frequency band of the frequency spectrum of the seat vibration displacement of each target seat during the occupant detection period is included in the frequency band of human breathing. If the frequency band of the frequency spectrum of the seat vibration displacement during the occupant detection period is included in the frequency band of human breathing, the threshold adjustment unit 321 calculates a value (hereinafter referred to as a "threshold increase value") based on the power component of the frequency spectrum of the seat vibration displacement during the occupant detection period for each target seat for which it has been determined that the frequency band of the frequency spectrum of the seat vibration displacement during the occupant detection period is included in the frequency band of human breathing. The threshold adjustment unit 321 calculates the threshold increase value using one of the following types of threshold increase value: power average, power median, power maximum, power value corresponding to a certain percentile, or mode. The threshold adjustment unit 321 sets the threshold increase value corresponding to the time change in seat vibration displacement of a target seat where the frequency band of the frequency spectrum during the occupant detection period of the seat vibration displacement is not included in the frequency band of human breathing to zero.

[0086] The threshold adjustment unit 321 may calculate the threshold increase value as any of the following types of values: the power average value, the power median value, the power maximum value, the power value corresponding to a certain percentile, or the most frequent value of the frequency spectrum; however, the type of the threshold increase value shall be the same as the occupant detection threshold, in other words, the same as the type of value based on the power component of the frequency band of human breathing in the frequency spectrum of the occupant candidate vibration displacement, which the occupant detection unit 307a compares with the adjusted occupant detection threshold when detecting the presence or absence of an occupant.

[0087] Then, the threshold adjustment unit 321 adds the calculated threshold increase value to the occupant detection threshold for each target seat, and sets the added value as the adjusted occupant detection threshold. For a given target seat, the threshold adjustment unit 321 adds the threshold increase value corresponding to the given target seat to the occupant detection threshold. For example, when the threshold adjustment unit 321 calculates the threshold increase value, the threshold adjustment unit 321 stores information indicating which target seat the threshold increase value was calculated for in an internal buffer or the like. The threshold adjustment unit 321 outputs information related to the adjusted occupant detection threshold (hereinafter referred to as "adjusted threshold information") to the occupant detection unit 307a. The adjusted threshold information is information in which information capable of identifying the target seat is associated with the adjusted occupant detection threshold.

[0088] The occupant detection unit 307a detects the presence or absence of an occupant for each target seat based on the occupant candidate vibration displacement information output from the occupant candidate vibration displacement calculation unit 302, using the frequency spectrum of the occupant candidate vibration displacement during the occupant detection period. Specifically, the occupant detection unit 307a detects the presence or absence of an occupant by comparing the power component of the frequency band of human breathing in the frequency spectrum of the occupant candidate vibration displacement during the occupant detection period with the adjusted occupant detection threshold. The occupant detection unit 307a can identify the adjusted occupant detection threshold corresponding to each target seat from the adjusted threshold information output from the threshold adjustment unit 321. For example, the occupant detection unit 307a detects the presence of an occupant if the power component of the frequency band of human breathing in the frequency spectrum of the occupant candidate vibration displacement during the occupant detection period is equal to or greater than the adjusted occupant detection threshold, and detects the absence of an occupant if it is less than the adjusted occupant detection threshold.

[0089] Here, Fig. 10 is a diagram illustrating an image of a process performed by the occupant detection unit 307a to detect the presence or absence of an occupant in a vehicle in the second embodiment. Fig. 10 is a diagram illustrating an example of adjustment of the occupant detection threshold performed by the threshold adjustment unit 321. Fig. 10 illustrates an example of adjustment of the occupant detection threshold performed by the threshold adjustment unit 321 when the time change of the occupant candidate vibration displacement and the time change of the seat vibration displacement are represented by a frequency spectrum. Fig. 10 also illustrates an example of a comparison performed by the occupant detection unit 307a between the power component of the frequency band of human breathing in the frequency spectrum of the occupant candidate vibration displacement during the occupant detection period and the adjusted occupant detection threshold (denoted as "adjusted detection threshold" in Fig. 10).

[0090] For example, if an occupant is currently present, it is assumed that the power component of the frequency band of human breathing in the frequency spectrum of the candidate occupant vibration displacement during the occupant detection period includes the power component of the frequency band of the occupant's breathing, etc., and the power component of the frequency band of the vibration of the target seat (see "1001" in Figure 10). Note that, for ease of understanding, it is assumed here that the frequency band of the vibration of the target seat is in a range similar to the frequency band of human breathing. The threshold adjustment unit 321 calculates a threshold increase value based on the power component of the frequency band of human breathing of the seat vibration displacement, and adds the calculated threshold increase value to the occupant detection threshold to obtain the adjusted occupant detection threshold.

[0091] As described above, once the threshold adjustment unit 321 calculates the adjusted occupant detection threshold, the occupant detection unit 307a then compares the power component of the frequency band of human breathing in the frequency spectrum of the occupant candidate vibration displacement during the occupant detection period with the adjusted occupant detection threshold. At this time, if the occupant candidate vibration displacement is represented as a time waveform, the occupant detection unit 307a converts the time waveform of the occupant candidate vibration displacement into a frequency spectrum. The occupant detection unit 307a compares the power component of the frequency band of human breathing in the frequency spectrum of the occupant candidate vibration displacement during the occupant detection period with the adjusted occupant detection threshold, which is a value that is larger by the threshold increase value, thereby relatively detecting the presence or absence of an occupant solely from vibrations due to the occupant's breathing, etc. In FIG. 10 , the vibrations due to the occupant's breathing, etc. in the occupant candidate vibration displacement are indicated by "1002."

[0092] On the other hand, for example, if an occupant is not currently present, and the occupant detection unit 307a uses the occupant detection threshold before the threshold adjustment unit 321 adds the threshold increase value to compare the occupant detection threshold with the power component of the frequency band of human breathing in the frequency spectrum of the occupant candidate vibration displacement during the occupant detection period, the power component of the frequency band of human breathing in the frequency spectrum of the occupant detection period may be greater than the occupant detection threshold. In other words, the occupant detection unit 307a may erroneously detect the presence of an occupant. In response to this, if the threshold adjustment unit 321 calculates a threshold increase value based on the power component of the frequency band of human breathing in the target seat vibration displacement and adds the calculated threshold increase value to the occupant detection threshold to obtain the adjusted occupant detection threshold, the adjusted occupant detection threshold will be greater than the power component of the frequency band of human breathing in the frequency spectrum of the occupant candidate vibration displacement during the occupant detection period, which does not include vibrations caused by the occupant. The occupant detection unit 307a can detect that there is no occupant without falsely detecting that there is an occupant by comparing the power component of the frequency band of human breathing in the frequency spectrum of the occupant candidate vibration displacement during the occupant detection period with the adjusted occupant detection threshold value, which is a value that is larger by the threshold increase value.

[0093] The value based on the power component that the occupant detection unit 307a compares with the adjusted occupant detection threshold may be any of the following values: the average power value, the median power value, the maximum power value, a power value corresponding to a certain percentile, or the mode of the frequency spectrum. It is sufficient that the adjusted occupant detection threshold and the value based on the power component that is compared with the adjusted occupant detection threshold are of the same type of value.

[0094] When the occupant detection unit 307a detects the presence of an occupant, it subsequently determines the type of the detected occupant, in other words, determines whether the occupant is an adult or a child. The method of determining the type of occupant by the occupant detection unit 307a is the same as the method of determining the type of occupant by the occupant detection unit 307 described in the first embodiment, and therefore a duplicated description will be omitted.

[0095] In the second embodiment, the process performed by the occupant detection unit 307a to detect the presence or absence of an occupant in the vehicle and determine the type of occupant when it detects that an occupant is present is referred to as "occupant detection process." After performing the occupant detection process as described above, the occupant detection unit 307a further controls the output of an alarm to an alarm device. In the second embodiment, the process of controlling the output of an alarm performed by the occupant detection unit 307a is referred to as "alarm output control process."

[0096] In the warning output control process, if the occupant detection process determines that there are occupants in the vehicle and that the occupants are only children, the occupant detection unit 307a outputs warning output control information to the warning device to cause the warning device to output a warning. When the warning output control information is output, the warning device outputs a warning based on the warning output control information.

[0097] The operation of the occupant detection device 300a according to the second embodiment will now be described. Fig. 11 is a flowchart for explaining the operation of the occupant detection device 300a according to the second embodiment. The occupant detection device 300a starts the operation shown in the flowchart of Fig. 11 when power is supplied to the occupant detection device 300a, for example, by turning on the power of the vehicle. The occupant detection device 300a repeats the operation shown in the flowchart of Fig. 11 until power is no longer supplied.

[0098] The details of the processing of steps ST1 to ST4 and step ST6 in Figure 11 are the same as the details of the processing of steps ST1 to ST4 and step ST6 in Figure 5, which have already been explained in embodiment 1, so the same step numbers will be used and duplicate explanations will be omitted.

[0099] The occupant detection unit 307a detects the presence or absence of an occupant in the vehicle based on the time change in the occupant candidate vibration displacement calculated for each target seat by the occupant candidate vibration displacement calculation unit 302 and the time change in the seat vibration displacement of each target seat calculated by the seat vibration displacement calculation unit 305, taking into account the vibration of each target seat, and performs occupant detection processing to determine the type of occupant if it detects that an occupant is present (step ST5a).

[0100] 11, the process of step ST1 and the processes of steps ST2 to ST4 are performed in parallel, but this is merely an example. For example, the process of step ST1 may be performed first, followed by the processes of steps ST2 to ST4, or vice versa. It is sufficient that the process of step ST1 and the processes of steps ST2 to ST4 are performed before the process of step ST5a is performed.

[0101] FIG. 12 is a flowchart for explaining details of the occupant detection process by the occupant detection unit 307a in step ST5a of FIG.

[0102] The threshold value adjustment unit 321 receives seat vibration displacement information from the seat vibration displacement calculation unit 305 via the occupant detection unit 307a. Then, the threshold value adjustment unit 321 determines whether the frequency band of the frequency spectrum of the seat vibration displacement of each target seat during the occupant detection period is included in the frequency band of human breathing (step ST1011).

[0103] In step ST1011, if the frequency band of the frequency spectrum of the seat vibration displacement of each target seat during the occupant detection period is included in the frequency band of human breathing (if "YES" in step ST1011), the threshold adjustment unit 321 calculates a threshold increase value corresponding to the time change of the seat vibration displacement of that target seat (step ST1012).In step ST1011, if the frequency band of the frequency spectrum of the seat vibration displacement of each target seat during the occupant detection period is not included in the frequency band of human breathing (if "NO" in step ST1011), the threshold adjustment unit 321 sets the threshold increase value corresponding to the time change of the seat vibration displacement of that target seat to zero (step ST1013).

[0104] The threshold adjusting unit 321 sets the adjusted occupant detection threshold value to the occupant detection threshold value for each target seat (step ST1014). The threshold adjusting unit 321 outputs the adjusted threshold value information to the occupant detection unit 307a.

[0105] Based on the adjusted threshold information output from the threshold adjustment unit 321, the occupant detection unit 307a determines, for each target seat, whether the power component of the human breathing frequency band in the frequency spectrum of the occupant candidate vibration displacement during the occupant detection period is greater than or equal to the adjusted occupant detection threshold (step ST1015).

[0106] In step ST1015, if the power component in the frequency band of human breathing in the frequency spectrum of the occupant candidate vibration displacement during the occupant detection period is equal to or greater than the adjusted occupant detection threshold (YES in step ST1015), the occupant detection unit 307a detects the presence of an occupant (step ST1016).The occupant detection unit 307a then determines the range of the frequency band during the occupant detection period of the occupant candidate vibration displacement corresponding to the target seat detected as having an occupant (step ST1018).

[0107] In step ST1018, as a result of determining which range of the frequency band of the occupant candidate vibration displacement corresponding to the target seat detected as having an occupant falls within the first range (in the case of "YES" in step ST1019), the occupant detection unit 307a determines that the occupant detected as having an occupant in step ST1016 is a child (step ST1020). Then, the occupant detection unit 307a ends the process shown in the flowchart of FIG. 12.

[0108] In step ST1018, the occupant detection unit 307a determines that the frequency band of the occupant candidate vibration displacement corresponding to the target seat detected as having an occupant falls within the second range ("NO" in step ST1019 and "YES" in step ST1021), and determines that the occupant detected as having an occupant in step ST1016 is an adult (step ST1022). The occupant detection unit 307a then terminates the process shown in the flowchart of FIG. 12. Furthermore, in the case where the occupant detection unit 307a determines that the frequency band of the noise-removed occupant candidate vibration displacement corresponding to the target seat detected as having an occupant falls within neither the first range nor the second range ("NO" in step ST1021), the occupant detection unit 307a terminates the process shown in the flowchart of FIG. 12.

[0109] On the other hand, in step ST1015, if the power component in the frequency band of human breathing in the frequency spectrum of the removed occupant candidate vibration displacement during the occupant detection period is less than the adjusted occupant detection threshold value (if "NO" in step ST1015), the occupant detection unit 307a detects that there is no occupant (step ST1017).The occupant detection unit 307a then ends the process shown in the flowchart of FIG.

[0110] In this way, the occupant detection device 300a calculates the time change in vibration displacement of the reflecting object (occupant candidate vibration displacement) for each target seat based on sensor information indicating the phase change of the reflected wave, which is the result of the radio wave emitted by the radio wave sensor 100 toward the target seat area set for each target seat in the vehicle cabin and reflected by the reflecting object in each target seat area. The occupant detection device 300a also calculates the time change in the vehicle vibration displacement (vehicle vibration displacement) based on the vibration information acquired by the vibration acquisition device 200 installed in the vehicle, and calculates the time change in the vibration displacement of the target seat (seat vibration displacement) for each target seat based on the calculated time change in the vehicle vibration displacement. The occupant detection device 300a then detects the presence or absence of an occupant in the vehicle based on the time change in the occupant candidate vibration displacement and the time change in the seat vibration displacement, taking into account the vibration of each target seat. Therefore, the occupant detection device 300a can improve the accuracy of occupant detection in the vehicle by taking into account the vibration of the target seat.

[0111] More specifically, in the occupant detection device 300a, the occupant detection unit 307a adjusts the occupant detection threshold used when detecting the presence or absence of an occupant for each target seat based on the time change in the vibration displacement of the target seat (seat vibration displacement) calculated by the seat vibration displacement calculation unit 305, and detects the presence or absence of an occupant by comparing the power component of the frequency band of human breathing in the frequency spectrum based on the time change in the vibration displacement of the reflecting object (occupant candidate vibration displacement) calculated by the occupant candidate vibration displacement calculation unit 302 with the adjusted occupant detection threshold. Therefore, the occupant detection device 300a can improve the accuracy of occupant detection in a vehicle by taking into account the vibration of the target seat.

[0112] Furthermore, the occupant detection device 300a according to the second embodiment calculates the time change of the vibration displacement of the target seat (seat vibration displacement) from the time change of the vehicle vibration displacement (vehicle vibration displacement) in order to improve the accuracy of occupant detection by taking into account the vibration of each target seat. In other words, the occupant detection device 300a can perform occupant detection taking into account the vibration of each target seat from the vibration information obtained from the vibration acquisition device 200 provided in the vehicle. Therefore, the occupant detection device 300a can contribute to reducing the cost of a system for detecting the presence or absence of an occupant in a vehicle.

[0113] The hardware configuration of the occupant detection device 300a according to the second embodiment is the same as that shown in FIGS. 8A and 8B in the first embodiment, and is therefore not shown in the drawings. In the second embodiment, the functions of the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307a, and the threshold adjustment unit 321 are realized by a processing circuit 101. That is, the occupant detection device 300a includes the processing circuit 101 for performing control to detect the presence or absence of an occupant in consideration of the vibration of the target seat. The processing circuit 101 may be dedicated hardware as shown in FIG. 8A, or a processor 104 that executes a program stored in a memory as shown in FIG. 8B.

[0114] The processing circuit 101 reads and executes the programs stored in the memory 105 to execute the functions of the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307a, and the threshold adjustment unit 321. That is, the occupant detection device 300a includes the memory 105 for storing a program that, when executed by the processing circuit 101, results in the execution of steps ST1 to ST6 in FIG. 11 described above. It can also be said that the program stored in the memory 105 causes a computer to execute the processing procedures or methods of the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307a, and the threshold adjustment unit 321. The occupant detection device 300a includes a device such as a radio wave sensor 100 or a vibration acquisition device 200, an input interface device 102 that performs wired or wireless communication, and an output interface device 103.

[0115] In the above-described second embodiment, it is assumed that the vibration acquiring device 200 is an acceleration sensor. However, this is merely an example. The vibration acquiring device 200 may be, for example, a vibration sensor. In this case, the occupant detection device 300a can acquire vehicle vibration displacement information directly from the vibration sensor. The occupant detection device 300a may acquire vehicle vibration displacement information as vibration information from the vibration sensor. In this case, the occupant detection device 300a may be configured without including the acceleration information acquiring unit 303. Furthermore, the occupant detection device 300a may omit the processing of step ST2 in the operation described using the flowchart of FIG. 11 .

[0116] In the second embodiment, the occupant detection unit 307a in the occupant detection device 300a has a function of determining the type of occupant in the occupant detection process and a function of executing the warning output control process, but this is merely an example. The functions of determining the type of occupant and the function of executing the warning output control process are not essential functions for the occupant detection device 300a.

[0117] In the second embodiment, the occupant detection device 300a is an in-vehicle device mounted on a vehicle, but this is merely an example. For example, the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307a, and the threshold adjustment unit 321 may all or partly be provided in a server, and the in-vehicle device and the server may form a system.

[0118] In the second embodiment, the occupant detection device 300a detects whether or not an occupant is present in a vehicle, but this is merely an example. The occupant detection device 300a is not limited to a vehicle, and may be configured to detect whether or not an occupant is present in a moving body other than a vehicle, such as an airplane or a train.

[0119] As described above, according to the second embodiment, the occupant detection device 300a includes an occupant candidate vibration displacement calculation unit 302 that calculates, for each target seat, a time change in vibration displacement of a reflecting object that is a source of reflection of the reflected wave, based on sensor information that indicates a phase change of a reflected wave that is generated when the radio wave is emitted by the radio wave sensor 100 toward a target seat area including the target seat set for each target seat that is a target for detecting the presence or absence of an occupant in the cabin of the moving body and that is reflected by a reflecting object that may include the occupant and the target seat in the target seat area, and a vibration acquisition device 202 that is provided in the moving body and acquires vibration information related to vibration of the main body of the moving body. 00, a moving body vibration displacement calculation unit 304 that calculates a time change in vibration displacement of the moving body based on the vibration information acquired by the moving body vibration displacement calculation unit 302, a seat vibration displacement calculation unit 305 that calculates a time change in vibration displacement of a target seat for each target seat based on the time change in vibration displacement of the moving body calculated by the moving body vibration displacement calculation unit 304, and an occupant detection unit 307a that detects the presence or absence of an occupant of the moving body in consideration of the vibration of each target seat based on the time change in vibration displacement of the reflecting object calculated by the occupant candidate vibration displacement calculation unit 302 and the time change in vibration displacement of each target seat calculated by the seat vibration displacement calculation unit 305. Therefore, the occupant detection device 300a can improve the accuracy of occupant detection in a moving body.

[0120] In detail, in the occupant detection device 300a, the occupant detection unit 307a includes a threshold adjustment unit 321 that adjusts the occupant detection threshold used to detect the presence or absence of an occupant for each target seat based on the time change in the vibration displacement of the target seat calculated by the seat vibration displacement calculation unit 305, and detects the presence or absence of an occupant by comparing the power component of the frequency band of human breathing in the frequency spectrum based on the time change in the vibration displacement of the reflecting object calculated by the occupant candidate vibration displacement calculation unit 302 with the adjusted occupant detection threshold adjusted by the threshold adjustment unit 321. Therefore, the occupant detection device 300a can improve the accuracy of occupant detection in a moving body.

[0121] Embodiment 3. In Embodiments 1 and 2, the vibrations generated in a moving body were assumed to be relatively small and continuous, such as those caused by idling of the moving body or vibrations from rough roads. However, in addition to relatively small and continuous vibrations, large and sudden vibrations can also occur in a moving body. In such cases, the moving body vibrates with large vibrations and high frequencies, while the seats in the moving body vibrate at a natural frequency when returning to their original stationary state from the sudden vibrations. Therefore, during a certain period until the large and sudden vibrations generated in the moving body settle down, it cannot be said that there is a correlation between the vibrations of the moving body and the seats. In Embodiment 3, an occupant detection device detects the presence or absence of an occupant while taking this into consideration.

[0122] 13 is a diagram showing an example configuration of an occupant detection device 300b according to embodiment 3. In embodiment 3, the occupant detection device 300b is connected to the radio wave sensor 100 and the vibration acquisition device 200. An example physical configuration of the occupant detection device 300b, the radio wave sensor 100, and the vibration acquisition device 200 according to embodiment 3 is similar to the example physical configuration of the occupant detection device 300, the radio wave sensor 100, and the vibration acquisition device 200 according to embodiment 1 described using FIG. 1 in embodiment 1, and therefore the same reference numerals are used and redundant description will be omitted.

[0123] In the third embodiment, as in the first embodiment, the vibration acquisition device 200 is assumed to be an acceleration sensor. Hereinafter, the vibration acquisition device 200 will be described as an acceleration sensor. Also, below, an occupant detection device 300b according to the third embodiment will be described assuming that vibrations are occurring in a vehicle. In the third embodiment, it is assumed that the vibrations occurring in a vehicle are large and sudden shaking caused by, for example, the opening and closing of a door or an impact from a strong wind. In the third embodiment, when such large and sudden shaking is occurring, the occupant detection device 300b detects the presence or absence of an occupant by taking into account the vibrations of each target seat.

[0124] 13, components similar to those of the occupant detection device 300 described in Embodiment 1 using FIG. 2 are denoted by the same reference numerals, and redundant description will be omitted. The occupant detection device 300b according to Embodiment 3 differs from the occupant detection device 300 according to Embodiment 1 in that it includes an occupant detection implementation determination unit 331. Furthermore, in the occupant detection device 300b according to Embodiment 3, the specific operation of the occupant detection unit 307b differs from the specific operation of the occupant detection unit 307 in the occupant detection device 300 according to Embodiment 1.

[0125] The occupant detection implementation determination unit 331 acquires vehicle vibration displacement information indicating a time change in vehicle vibration displacement from the moving body vibration displacement calculation unit 304. In the third embodiment, the moving body vibration displacement calculation unit 304 outputs the vehicle vibration displacement information to the seat vibration displacement calculation unit 305 and the occupant detection implementation determination unit 331. Based on the vehicle vibration displacement information, the occupant detection implementation determination unit 331 calculates a specific reference value (hereinafter referred to as a "vibration reference value") of vehicle vibration displacement during the occupant detection period.

[0126] The vibration reference value may be the average value, median value, maximum value, or a value corresponding to a certain percentile of the time waveform during the occupant detection period, or the power average value, power median value, power maximum value, power value corresponding to a certain percentile, or mode of the frequency spectrum during the occupant detection period. In the third embodiment, the occupant detection period may be a period of a predetermined fixed length, or a period of a length dependent on the magnitude of the vehicle vibration displacement. For example, the occupant detection implementation determination unit 331 lengthens the occupant detection period as the magnitude of the vehicle vibration displacement increases. It is assumed that the conditions for determining the length of the occupant detection period depending on the magnitude of the vehicle vibration displacement are set in advance and stored in a location accessible by the occupant detection implementation determination unit 331.

[0127] After calculating the vibration reference value for the occupant detection period, the occupant detection implementation determination unit 331 compares the calculated vibration reference value with a preset threshold value (hereinafter referred to as the "vibration determination threshold value"). The vibration determination threshold value is set in advance by an administrator or the like and stored in a location that the occupant detection implementation determination unit 331 can refer to. If the vibration reference value is equal to or less than the vibration determination threshold value, the occupant detection implementation determination unit 331 determines that the occupant detection process can be performed during the occupant detection period. If the vibration reference value is greater than the vibration determination threshold value, the occupant detection implementation determination unit 331 determines that the occupant detection process cannot be performed during the occupant detection period.

[0128] The occupant detection implementation determination unit 331 may calculate the vibration reference value for each coordinate axis of the acceleration sensor, or may calculate it as a vector composite value. When the vibration reference value is set as a value for each coordinate axis of the acceleration sensor, the occupant detection implementation determination unit 331 compares the vibration reference value with the vibration determination threshold for each coordinate axis of the acceleration sensor. In this case, the occupant detection implementation determination unit 331 may enable the occupant detection period and the occupant detection process when the vibration reference values ​​corresponding to all coordinate axes are equal to or less than the vibration determination threshold, or may enable the occupant detection period and the occupant detection process when the vibration reference value corresponding to a specific coordinate axis is equal to or less than the vibration determination threshold.

[0129] The occupant detection execution determination unit 331 outputs information indicating the determination result of whether or not to execute the occupant detection process (hereinafter referred to as "occupant detection execution information") to the occupant detection unit 307b. The occupant detection execution information includes an occupant detection period, information indicating whether or not to execute the occupant detection process, and information indicating the start time and end time of the occupant detection period.

[0130] In embodiment 3, the process performed by the occupant detection implementation determination unit 331 to determine whether or not the occupant detection process can be implemented during the occupant detection period, as described above, is referred to as the "occupant detection implementation feasibility determination process."

[0131] The occupant detection unit 307b performs occupant detection processing to detect the presence or absence of an occupant when the occupant detection execution determination unit 331 determines that it is possible to detect the presence or absence of an occupant during the occupant detection period based on the occupant detection execution feasibility information output from the occupant detection execution determination unit 331. Details of the occupant detection processing by the occupant detection unit 307b have been described in the first embodiment, so a duplicated description will be omitted. Note that, after performing the occupant detection processing, the occupant detection unit 307b performs the warning output control processing described in the first embodiment. When the occupant detection execution determination unit 331 determines that it is not possible to detect the presence or absence of an occupant during the occupant detection period, the occupant detection unit 307b does not perform the occupant detection processing.

[0132] 14 is a diagram illustrating an example of the occupant detection implementation determination process performed by the occupant detection implementation determination unit 331 in the third embodiment. In FIG. 14, as an example, the time change of the vehicle vibration displacement is shown as a time waveform, and the occupant detection implementation determination unit 331 sets the vibration reference value as the average value of the time waveform. In FIG. 14, the graph on the left shows an example of the time change of the seat vibration displacement, and the graph on the right shows an example of the time change of the vehicle vibration displacement.

[0133] When a large, sudden vibration occurs in a vehicle, the vehicle vibrates with large vibrations and high frequencies (see an example of the change in vehicle vibration displacement over time on the right side of Figure 14). In contrast, when the target seat returns to its original stationary state after the sudden vibration, it vibrates at a specific frequency (see an example of the change in seat vibration displacement over time on the left side of Figure 14). During the occupant detection period, the vibration frequency of the target seat is different from the vibration frequency of the vehicle body. In the first embodiment, the occupant detection device 300 calculates the seat vibration displacement under the assumption that there is a correlation between the vehicle vibration and the vibration of the target seat, and removes the vibration component of the seat vibration displacement from the vibration component of the occupant candidate vibration displacement. However, if this assumption does not hold, the occupant detection device 300 may not be able to remove the vibration component of the target seat vibration displacement from the vibration component of the occupant candidate vibration displacement, which may prevent erroneous detection of the presence or absence of an occupant. Therefore, in the occupant detection device 300b according to the third embodiment, the occupant detection implementation determination unit 331 calculates a vibration reference value for the occupant detection period of the vehicle vibration displacement, and determines that the occupant detection process can be implemented if the calculated vibration reference value is equal to or less than the vibration determination threshold, and determines that the occupant detection process cannot be implemented if the calculated vibration reference value is greater than the vibration determination threshold. This prevents the occupant detection device 300b from falsely detecting the presence or absence of an occupant by detecting the presence or absence of an occupant when it cannot be determined that there is a correlation between the vehicle vibration and the vibration of the target seat. Note that the detection of the presence or absence of an occupant is performed by the occupant detection unit 307b as described above.

[0134] The operation of the occupant detection device 300b according to the third embodiment will now be described. Fig. 15 is a flowchart for explaining the operation of the occupant detection device 300b according to the third embodiment. The occupant detection device 300b starts the operation shown in the flowchart of Fig. 15 when, for example, the power supply to the occupant detection device 300b is turned on, which is a trigger. The occupant detection device 300b repeats the operation shown in the flowchart of Fig. 15 until, for example, the power supply is no longer turned on.

[0135] The details of the processing of steps ST1 to ST4 and steps ST5 to ST6 in Figure 15 are the same as the details of the processing of steps ST1 to ST4 and steps ST5 to ST6 in Figure 5, which have already been explained in embodiment 1, so the same step numbers will be used and duplicate explanations will be omitted.

[0136] The occupant detection implementation determination unit 331 acquires the vehicle vibration displacement information from the moving body vibration displacement calculation unit 304, and performs occupant detection implementation determination processing based on the acquired vehicle vibration displacement information (step ST500). The occupant detection implementation determination unit 331 outputs the occupant detection implementation information to the occupant detection unit 307b.

[0137] The occupant detection unit 307b determines whether the occupant detection execution determination unit 331 has determined that the presence or absence of an occupant can be detected based on the occupant detection execution information output from the occupant detection execution determination unit 331 in step ST500 (step ST501). If the occupant detection unit 307b determines in step ST501 that the occupant detection execution determination unit 331 has determined that the presence or absence of an occupant can be detected (in the case of "YES" in step ST501), the operation of the occupant detection device 300b proceeds to the processing of step ST5. If the occupant detection unit 307b determines in step ST501 that the occupant detection execution determination unit 331 has determined that the presence or absence of an occupant cannot be detected (in the case of "NO" in step ST501), the occupant detection device 300b ends the processing shown in the flowchart of FIG. 15.

[0138] In the flowchart of FIG. 15, the process of step ST1 and the processes of steps ST2 to ST4 are performed in parallel, but this is merely an example. For example, the process of step ST1 may be performed first, followed by the processes of steps ST2 to ST4, or vice versa. It is sufficient that the process of step ST1 and the processes of steps ST2 to ST4 are performed before the process of step ST5 is performed. In addition, in the flowchart of FIG. 15, the process of step ST500 is performed after the process of step ST4, but this is merely an example. For example, the process of step ST500 may be performed in parallel with the process of step ST4.

[0139] FIG. 16 is a flowchart for explaining details of the occupant detection execution possibility determination process by the occupant detection execution determination unit 331 in step ST500 of FIG.

[0140] The occupant detection execution determination unit 331 acquires vehicle vibration displacement information indicating a time change in vehicle vibration displacement from the moving body vibration displacement calculation unit 304. Then, the occupant detection execution determination unit 331 calculates a vibration reference value of the vehicle vibration displacement during the occupant detection period based on the vehicle vibration displacement information (step ST31).

[0141] After calculating the reference vibration value for the occupant detection period of the vehicle vibration displacement, the occupant detection execution determination unit 331 compares the calculated reference vibration value with the vibration determination threshold to determine whether the reference vibration value is equal to or less than the vibration determination threshold (step ST32). If it is determined in step ST32 that the reference vibration value is equal to or less than the vibration determination threshold ("YES" in step ST32), the occupant detection execution determination unit 331 determines that the occupant detection process can be performed during the occupant detection period (step ST33). Then, the occupant detection execution determination unit 331 outputs occupant detection execution information to the occupant detection unit 307b and terminates the process shown in the flowchart of FIG. 16. If it is determined in step ST32 that the reference vibration value is greater than the vibration determination threshold ("NO" in step ST32), the occupant detection execution determination unit 331 determines that the occupant detection process cannot be performed during the occupant detection period (step ST34). Then, the occupant detection implementation determination unit 331 outputs occupant detection implementation information to the occupant detection unit 307b, and ends the processing shown in the flowchart of FIG.

[0142] In this way, the occupant detection device 300b determines that the presence or absence of an occupant can be detected when the vibration displacement of the vehicle is equal to or less than the vibration determination threshold during the occupant detection period, and determines that the presence or absence of an occupant cannot be detected when the vibration displacement is greater than the vibration determination threshold. In other words, the occupant detection device 300b detects the presence or absence of an occupant only during the occupant detection period during which it is determined that the presence or absence of an occupant can be detected.

[0143] In the first embodiment, it is assumed that the vibrations occurring in the vehicle are relatively small and continuous, and under the assumption that there is a correlation between the vibrations of the vehicle and the vibrations of the target seat in such a case, the time change of the seat vibration displacement for each target seat is calculated based on the time change of the vehicle vibration displacement, and the presence or absence of an occupant is detected after removing the vibration component of the seat vibration displacement from the vibration component of the candidate occupant vibration displacement using the calculated time change of the seat vibration displacement. However, as described above, when a large and sudden vibration occurs in the vehicle, the vehicle vibrates with large vibrations and high frequencies, but the target seat vibrates at its natural frequency when returning to its original stationary state from the sudden vibration, and it cannot be said that there is a correlation between the vibrations of the vehicle and the vibrations of the target seat. If the occupant detection device 300b were to detect the presence or absence of an occupant using the method employed by the occupant detection device 300 according to the first embodiment, based on the assumption that there is a correlation between the vibration of the vehicle and the vibration of the target seat when a large and sudden sway occurs in the vehicle, the occupant detection device 300b would not be able to remove the vibration component of the seat vibration displacement from the vibration component of the occupant candidate vibration displacement, and it may not be possible to prevent erroneous detection of the presence or absence of an occupant. By performing the occupant detection process only during the occupant detection period when the vibration displacement of the vehicle is equal to or less than the vibration determination threshold, the occupant detection device 300b can prevent erroneous detection of the presence or absence of an occupant that may occur when a large and sudden sway occurs in the vehicle, and can improve the accuracy of occupant detection by taking into account the vibration of the target seat in the vehicle.

[0144] The hardware configuration of the occupant detection device 300b according to the third embodiment is the same as that shown in FIGS. 8A and 8B in the first embodiment, and is therefore not shown in the drawings. In the third embodiment, the functions of the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307b, the noise reduction unit 306, and the occupant detection implementation determination unit 331 are realized by a processing circuit 101. That is, the occupant detection device 300b includes the processing circuit 101 for performing control to determine whether a sudden shaking is occurring and to detect the presence or absence of an occupant in consideration of the vibration of the target seat. The processing circuit 101 may be dedicated hardware as shown in FIG. 8A, or a processor 104 that executes a program stored in a memory as shown in FIG. 8B.

[0145] The processing circuit 101 reads out and executes the programs stored in the memory 105, thereby executing the functions of the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307b, the noise removal unit 306, and the occupant detection implementation determination unit 331. That is, the occupant detection device 300b includes the memory 105 for storing a program that, when executed by the processing circuit 101, results in the execution of steps ST1 to ST6 in Fig. 15 described above. It can also be said that the program stored in the memory 105 causes the computer to execute the processing procedures or methods of the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307b, the noise removal unit 306, and the occupant detection implementation determination unit 331. The occupant detection device 300b includes a device such as the radio wave sensor 100 or the vibration acquisition device 200, and an input interface device 102 and an output interface device 103 that perform wired or wireless communication.

[0146] In the above third embodiment, it is assumed that the vibration acquiring device 200 is an acceleration sensor. However, this is merely an example. The vibration acquiring device 200 may be, for example, a vibration sensor. In this case, the occupant detection device 300b can acquire vehicle vibration displacement information directly from the vibration sensor. The occupant detection device 300b may acquire vehicle vibration displacement information as vibration information from the vibration sensor. In this case, the occupant detection device 300b may be configured without including the acceleration information acquiring unit 303. Furthermore, the occupant detection device 300a may omit the processing of step ST2 in the operation described using the flowchart of FIG. 15 .

[0147] In the third embodiment, the occupant detection unit 307b in the occupant detection device 300b has a function of determining the type of occupant in the occupant detection process and a function of executing the warning output control process, but this is merely an example. The functions of determining the type of occupant and the function of executing the warning output control process are not essential functions for the occupant detection device 300b.

[0148] In the third embodiment, the occupant detection device 300b is an in-vehicle device mounted on a vehicle, but this is merely an example. For example, the radio wave information acquisition unit 301, the occupant candidate vibration displacement calculation unit 302, the acceleration information acquisition unit 303, the moving body vibration displacement calculation unit 304, the seat vibration displacement calculation unit 305, the occupant detection unit 307b, the noise removal unit 306, and the occupant detection implementation determination unit 331 may all or partly be provided in a server, and the in-vehicle device and the server may form a system.

[0149] In the third embodiment, the occupant detection device 300b detects whether or not an occupant is present in a vehicle, but this is merely an example. The occupant detection device 300b may be configured to detect whether or not an occupant is present in a moving body other than a vehicle, such as an airplane or a train.

[0150] Furthermore, in the above-described embodiment 3, the configuration example of the occupant detection device 300b is an example in which the occupant detection device 300 according to embodiment 1 is equipped with an occupant detection implementation determination unit 331, but this is merely an example, and an example configuration in which the occupant detection device 300a according to embodiment 2 is equipped with an occupant detection implementation determination unit 331 may also be used.

[0151] As described above, according to the third embodiment, the occupant detection device 300b includes the occupant detection implementation determination unit 331 that determines whether the presence or absence of an occupant can be detected when the vibration displacement of the moving body (vehicle vibration displacement) calculated by the moving body vibration displacement calculation unit 304 during the occupant detection period is equal to or less than the vibration determination threshold, and determines whether the presence or absence of an occupant cannot be detected when the vibration displacement of the moving body (vehicle vibration displacement) is greater than the vibration determination threshold, and the occupant detection unit 307b is configured to detect the presence or absence of an occupant when the occupant detection implementation determination unit 331 determines that the presence or absence of an occupant can be detected. Therefore, the occupant detection device 300b can prevent erroneous detection of the presence or absence of an occupant that may occur when large and sudden shaking occurs in the vehicle, and can improve the accuracy of occupant detection in the vehicle by taking into account the vibration of the target seat.

[0152] It should be noted that the embodiments may be freely combined, or any of the components in each embodiment may be modified, or any of the components in each embodiment may be omitted.

[0153] The status detection device according to the present disclosure improves the accuracy of occupant detection in a moving body.

[0154] 300, 300a, 300b Occupant detection device, 301 Radio wave information acquisition unit, 302 Occupant candidate vibration displacement calculation unit, 303 Acceleration information acquisition unit, 304 Moving body vibration displacement calculation unit, 305 Seat vibration displacement calculation unit, 306 Noise removal unit, 307, 307a, 307b Occupant detection unit, 321 Threshold value adjustment unit, 331 Occupant detection implementation determination unit, 100 Radio wave sensor, 200 Vibration acquisition device, 101 Processing circuit, 102 Input interface device, 103 Output interface device, 104 Processor, 105 Memory.

Claims

1. A candidate occupant vibration displacement calculation unit that calculates, for each target seat, the time change in vibration displacement of a reflecting object that is the source of the reflected wave, based on sensor information indicating a phase change of a reflected wave reflected by a reflecting object that may include the occupant and the target seat in the target seat area, in response to a radio wave emitted by a radio wave sensor toward a target seat area including the target seat set for each target seat for detecting the presence or absence of an occupant in the interior of a moving body; a moving body vibration displacement calculation unit that calculates, for each target seat, the time change in vibration displacement of the reflecting object that is the source of the reflected wave, based on the vibration information acquired by a vibration acquisition device that is provided in the moving body and acquires vibration information related to the vibration of the main body of the moving body; and a seat vibration displacement calculation unit that calculates, for each target seat, the time change in vibration displacement of the target seat based on the time change in the vibration displacement of the moving body calculated by the moving body vibration displacement calculation unit. an occupant detection unit that detects the presence or absence of an occupant in the moving body, taking into account the vibration of each target seat, based on the time change of the vibration displacement of the reflecting object calculated by the candidate occupant vibration displacement calculation unit and the time change of the vibration displacement of each target seat calculated by the seat vibration displacement calculation unit.

2. The occupant detection unit is provided with a noise removal unit that calculates, for each target seat, a time change in noise-removed occupant candidate vibration displacement, which is the time change in the vibration displacement of the reflecting object after subtracting the time change in the vibration displacement of the target seat calculated by the seat vibration displacement calculation unit from the time change in the vibration displacement of the reflecting object calculated by the occupant candidate vibration displacement calculation unit, and detects the presence or absence of an occupant by comparing the power component of the frequency band of human breathing in a frequency spectrum based on the time change in the noise-removed occupant candidate vibration displacement calculated by the noise removal unit with an occupant detection threshold value. The occupant detection device described in claim 1, characterized in that 3. The occupant detection device according to claim 2, characterized in that when the occupant detection unit detects the presence of an occupant based on the time change in vibration displacement of the noise-removed occupant candidate, it determines the type of occupant for each target seat.

4. The occupant detection device of claim 3, characterized in that the types of occupants include children and adults, and the occupant detection unit determines that the occupant is a child when the frequency band of the noise-removed occupant candidate vibration displacement during the occupant detection period is within a first range, and determines that the occupant is an adult when the frequency band of the noise-removed occupant candidate vibration displacement during the occupant detection period is within a second range.

5. The occupant detection device according to claim 1, characterized in that the occupant detection unit is provided with a threshold adjustment unit that adjusts an occupant detection threshold used when detecting the presence or absence of an occupant based on the time change in the vibration displacement of the target seat calculated by the seat vibration displacement calculation unit for each target seat, and detects the presence or absence of an occupant by comparing the power component of the frequency band of human breathing in a frequency spectrum based on the time change in the vibration displacement of the reflecting object calculated by the occupant candidate vibration displacement calculation unit with the adjusted occupant detection threshold adjusted by the threshold adjustment unit.

6. The occupant detection device according to claim 5, characterized in that when the occupant detection unit detects the presence of an occupant based on the change over time in the vibration displacement of the reflecting object, it determines the type of occupant for each target seat.

7. The occupant detection device of claim 6, characterized in that the types of occupants include children and adults, and the occupant detection unit determines that the occupant is a child when the frequency band of the vibration displacement of the reflecting object during the occupant detection period is within a first range, and determines that the occupant is an adult when the frequency band of the vibration displacement of the reflecting object during the occupant detection period is within a second range.

8. An occupant detection device as described in claim 4 or claim 7, characterized in that the occupant detection unit outputs alarm output control information to an alarm device to output an alarm when the only occupant detected to be present in the cabin of the moving body is a child.

9. An occupant detection device as described in any one of claims 1 to 8, characterized in that it is further provided with an occupant detection implementation determination unit which determines that the presence or absence of an occupant can be detected when the vibration displacement of the moving body calculated by the moving body vibration displacement calculation unit during the occupant detection period is equal to or less than a vibration judgment threshold, and that the presence or absence of an occupant cannot be detected when the vibration displacement of the moving body is greater than the vibration judgment threshold, and the occupant detection unit detects the presence or absence of an occupant when the occupant detection implementation determination unit determines that the presence or absence of an occupant can be detected.

10. An occupant detection device as described in any one of claims 1 to 9, characterized in that the seat vibration displacement calculation unit calculates the time change of the vibration displacement of the target seat by vector converting the time change of the vibration displacement of the moving body.

11. An occupant detection device according to any one of claims 1 to 10, characterized in that the vibration acquisition device is an acceleration sensor.

12. An occupant detection device according to any one of claims 1 to 10, characterized in that the vibration acquisition device is a vibration sensor.

13. A step in which an occupant candidate vibration displacement calculation unit calculates, for each target seat, a time change in vibration displacement of a reflecting object that is the source of the reflected wave, based on sensor information indicating a phase change of a reflected wave reflected by a reflecting object that may include the occupant and the target seat in the target seat area, in response to a radio wave emitted toward a target seat area including the target seat set for each target seat that is a target for detecting the presence or absence of an occupant in the interior of the moving body by a radio wave sensor; a step in which a moving body vibration displacement calculation unit calculates, for each target seat, a time change in vibration displacement of the reflecting object that is the source of the reflected wave, based on sensor information indicating a phase change of a reflected wave reflected by the reflecting object in the target seat area that may include the occupant and the target seat; a step in which a moving body vibration displacement calculation unit calculates, for each target seat, a time change in vibration displacement of the moving body, based on the vibration information acquired by a vibration acquisition device that is provided in the moving body and acquires vibration information related to the vibration of the main body of the moving body; a step in which a seat vibration displacement calculation unit calculates, for each target seat, a time change in vibration displacement of the target seat, based on the time change in vibration displacement of the moving body calculated by the moving body vibration displacement calculation unit; an occupant detection unit detecting the presence or absence of an occupant in the moving body, taking into account the vibration of each target seat, based on the time change in the vibration displacement of the reflecting object calculated by the occupant candidate vibration displacement calculation unit and the time change in the vibration displacement of each target seat calculated by the seat vibration displacement calculation unit.

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