JP7829313B2 - In-vehicle biological detection device and method - Google Patents

Description

This invention relates to a biological detection means for detecting living organisms inside a vehicle.

Mechanical parking systems (e.g., elevator type, vertical circulation type, etc.) are equipped with a passenger compartment for vehicles (e.g., passenger cars) to enter and exit (park or take off), and entrance/exit doors for vehicles to enter and exit the passenger compartment.
When the mechanical parking system is in operation, in order to ensure safety, it is necessary to confirm that there are no people or animals (hereinafter referred to as "living beings") inside the vehicle, and that there are no items other than people, animals, and vehicles (hereinafter referred to as "foreign objects") inside the passenger compartment, and to fully close the entrance and exit doors.
Traditionally, this verification was carried out by detecting foreign objects using photoelectric sensors or motion sensors, or by visual inspection by a caretaker.

However, foreign object detection using photoelectric sensors or motion sensors, as well as visual inspection by the manager, had the potential to overlook living beings (people or animals) inside the vehicle.
To solve this problem, a means for detecting living organisms inside a vehicle is disclosed in Patent Document 1.

Patent Document 1 describes a "parking lot human body detection device" comprising a microwave oscillator, an antenna, a detection means, a change component detection means, a comparison means, and an alarm means. The antenna transmits microwaves toward the vehicle and receives ambient microwaves. The detection means detects reflected waves from the received microwaves that are reflected inside and near the vehicle. The change component detection means extracts the change component of the signal caused by the breathing of a person in the vicinity (0.2 to 0.5 Hz) based on the signal from the detection means. The comparison means compares the output of the change component detection means with a predetermined reference value, and the alarm means notifies the presence of a person inside or near the vehicle.

Patent No. 3527362

However, the method described in Patent Document 1 detects the presence of a person based on "the signal change component due to a person's breathing at 0.2 to 0.5 Hz," so if there is body movement with a displacement amount that is an order of magnitude or more greater than that of breathing, the respiratory component will be buried in the signal component of the body movement and cannot be detected.
Conversely, in cases of sleeping individuals, children, infants, intoxicated persons, or seriously ill individuals, displacement due to body movement or breathing may be small and almost undetectable.

Furthermore, when millimeter waves are used to detect vital vibrations in living organisms (humans or animals), reflected waves from non-living objects (vehicle body, doors, interior walls) can act as noise, sometimes preventing accurate detection of vital vibrations.
For example, vital signs vibrations could not be detected accurately in the following cases:

(1) When strong winds blow around the building of a mechanical parking system, even if the entrance and exit doors are closed, wind will generally blow into the vehicle due to the ventilation structure.
If air blows into the warehouse and the pallet on which the vehicle is mounted has low rigidity, vibrations will occur with frequency components related to the natural frequencies of the vehicle and the pallet, and these vibrations will persist for a long time. If these vibration components occur in the frequency components being evaluated, they will be indistinguishable from the vibration components of the vehicle itself.

(2) Inside the building of the mechanical parking system, there are suspended structures such as elevator equipment and internal wiring, and wind blowing in causes movement (swaying and vibration) in them. When a vehicle is inside the parking system, millimeter waves are reflected in various directions by the vehicle body, and diffuse reflection inside the parking system causes false detection of an object that is moving along the multipath path.
(3) Because the measurement areas of the in-vehicle sensors and the vehicle body sensors are not the same, background vibration information is difficult to match, and the radio wave reflection characteristics differ depending on the shape of the vehicle. For this reason, it is difficult to completely cancel out (remove) the vehicle vibration component contained in the signal obtained from the in-vehicle sensors with the vibration component obtained from the signal obtained from the vehicle body sensors.

This invention was devised to solve the problems described above. Specifically, the objective of this invention is to provide an in-vehicle biological detection means that can reliably detect living organisms inside a vehicle by reducing the influence of noise from non-biological objects, even in the presence of wind, and by detecting signals from respiration, pulse, and body movement without them being masked by each other.

According to the present invention, an in-vehicle biological detection device detects living organisms inside a vehicle by irradiating a vehicle parked in the boarding/alighting area inside the vehicle with millimeter waves,
An anti-reflective device for preventing the reflection of millimeter waves in the space surrounding the vehicle,
A millimeter-wave sensor for use inside a vehicle that irradiates the interior of the vehicle with millimeter waves through its window glass and receives the reflected wave data,
An intermediate frequency amplifier that amplifies the frequency components of respiration, pulse, and body movement from the reflected wave data with different amplification factors and outputs an amplified signal,
A discrimination device that determines the presence or absence of the living organism from the amplified signal,
A vehicle-in-vehicle biological detection device is provided, which includes a vibration damping device that changes the vibration mode of the pallet on which the vehicle is placed to a higher order, thereby changing the vibration frequency distribution of the vehicle .

Furthermore, according to the present invention, a method for detecting living organisms inside a vehicle by irradiating a vehicle parked in the boarding/alighting area inside the vehicle with millimeter waves,
(A) The reflection of the millimeter waves in the space surrounding the vehicle is prevented by an anti-reflective device,
(B) The vibration mode of the pallet on which the vehicle is placed is changed to a higher order by the vibration damping device, thereby changing the vibration frequency distribution of the vehicle.
(C) The vehicle placed on the pallet is irradiated with the millimeter waves into the vehicle through its window glass and the reflected wave data is received.
(D) The frequency components of respiration, pulse, and body movement from the reflected wave data are amplified at different amplification rates and an amplified signal is output.
(E) A method for detecting a living organism inside a vehicle is provided, which determines the presence or absence of the living organism from the amplified signal.

According to the present invention, an intermediate frequency amplifier amplifies the frequency components of respiration, pulse, and body movement from the reflected wave data with different amplification factors and outputs an amplified signal. This allows for the detection of each vital signal without them being overshadowed, ensuring reliable detection of living organisms within the vehicle.

Furthermore, the anti-reflective device prevents millimeter-wave reflection from the outside of the vehicle, thus reducing the impact of noise caused by diffuse reflection from objects outside the vehicle, even when wind is present.

Therefore, even in the presence of wind, the system can reduce the influence of noise from non-living objects, allowing for reliable detection of living organisms inside the vehicle by detecting signals from respiration, pulse, and body movement without them being masked by each other.

This is a plan view of the in-vehicle biological detection device according to the present invention. This is a side view of Figure 1. This is a diagram illustrating the layout of a millimeter-wave sensor for use inside a vehicle. This is an overall diagram of the in-vehicle biometric detection system. This is an overall flowchart of the in-vehicle biological detection method of the present invention. This is a test result demonstrating the effectiveness of the intermediate door. This is a test result demonstrating the effectiveness of the vibration damping device. This is an explanatory diagram of the vibration modes of a beam supported at both ends.

The embodiments of the present invention will be described below with reference to the drawings. Common parts in each figure are denoted by the same reference numerals, and redundant explanations are omitted.

Figure 1 is a plan view of the in-vehicle biological detection device 10 according to the present invention, and Figure 2 is a side view of Figure 1.
In Figures 1 and 2, 1 is a mechanical parking system, 2 is a passenger compartment, 2a is the interior wall of the passenger compartment, 3 is the entrance/exit door, 4 is a vehicle, 5 is the passenger area inside the garage (passenger compartment), and 6 is a pallet located in the passenger area on which the vehicle 4 is placed.
The boarding/alighting compartment 2 refers to the area inside the inner wall 2a. The boarding/alighting area 5 is pre-set inside the boarding/alighting compartment 2. The pallet 6 can be raised and lowered or moved horizontally with the vehicle 4 on it, and is placed stationary in the boarding/alighting area 5 when the vehicle 4 is parked.

The mechanical parking system 1 may be, for example, an elevator type or a vertical circulation type, but other types of mechanical parking systems may also be used, as long as the pallet 6 on which the vehicle 4 is placed is located in the entry/exit area 5 when the vehicle is parked.

The in-vehicle biological detection device 10 is a device that detects living organisms inside a vehicle by irradiating the vehicle 4 with millimeter waves 7. In Figure 1, the in-vehicle biological detection device 10 comprises an in-vehicle millimeter wave sensor 12, an intermediate frequency amplifier 14, and a discrimination device 16.

The in-vehicle millimeter-wave sensor 12 emits millimeter waves 7 into the vehicle 4 through its windows (front windshield or side windows) and receives the reflected wave data 8.
In Figure 1, the in-vehicle millimeter-wave sensor 12 includes a forward millimeter-wave sensor 12A and a side millimeter-wave sensor 12B.
The intermediate frequency amplifier 14 and the discrimination device 16 process the reflected wave data 8 from the forward millimeter-wave sensor 12A and the side millimeter-wave sensor 12B.

The forward millimeter-wave sensor 12A emits millimeter waves 7 from the front to a vehicle 4 parked inside the boarding/alighting area 5, passing through the windshield, and receives the reflected wave data 8. The reason for emitting millimeter waves 7 through the windshield is that high visibility is required for the windshield, and therefore high-performance tinted glass is not used.
The side millimeter-wave sensor 12B emits millimeter waves 7 from the side of the vehicle 4, passing through the side glass of the vehicle.

As shown in Figure 2, the millimeter waves 7 are preferably irradiated horizontally downwards to narrow the angle of incidence to the windshield and to receive reflected wave data 8 from the entire interior of the vehicle. This irradiation angle α is, for example, 5 to 15 degrees downwards, and more preferably 10 degrees. However, the present invention is not limited to this, and the irradiation angle may also be horizontal.

Figure 3 is an explanatory diagram of the arrangement of the in-vehicle millimeter-wave sensor 12. In this figure, (A) is an arrangement view relative to the front of the vehicle 4, and (B) is an arrangement view relative to the side of the vehicle 4.

In Figure 3(A), the in-vehicle biodetection device 10 includes, in addition to the in-vehicle millimeter-wave sensor 12 described above, a vehicle body millimeter-wave sensor 12C and a rear-facing millimeter-wave sensor 12D.
The in-vehicle millimeter-wave sensor 12 (front millimeter-wave sensor 12A and side millimeter-wave sensor 12B), the vehicle body millimeter-wave sensor 12C, and the rear millimeter-wave sensor 12D are all millimeter-wave sensors.

In this invention, "millimeter-wave sensor" means millimeter-wave radar, millimeter-wave Doppler sensor, or millimeter-wave Doppler radar.
A "millimeter-wave radar" is a type of radar that uses millimeter-wave radio waves to measure the distance, speed, and angle to an object.
A "millimeter-wave Doppler sensor" is a sensor that utilizes the Doppler effect to detect moving objects by receiving reflected millimeter waves that have been emitted and using the difference between the emitted frequency and the received frequency.
A "millimeter-wave Doppler radar" is a type of radar that can observe the relative speed and displacement of an object by observing the frequency shift caused by the Doppler effect.

Millimeter-wave sensors have the function of detecting living organisms using the Doppler effect and avoiding unintended detection of living organisms by filtering out a predetermined frequency band.
Furthermore, millimeter-wave sensors, due to their short wavelength, can achieve highly accurate detection, capable of detecting movements as small as 0.1 mm. Therefore, they can detect chest movements during breathing in living organisms (humans or animals), as well as chest movements caused by heartbeats.

In Figure 3, multiple (9) forward millimeter-wave sensors 12A are installed in three horizontal rows corresponding to the driver's seat, passenger seat, and the area between them, and in three vertical rows corresponding to the differences in vehicle types.
In other words, nine forward millimeter-wave sensors 12A are arranged in groups of three at heights h1, h2, and h3, spaced apart in the width direction. Heights h1, h2, and h3 are set to accommodate multiple vehicle types, while the three in the width direction are set to correspond to the center of the vehicle 4, the driver's seat, and the passenger seat.
The distance between the centers of the three forward millimeter-wave sensors 12A in the width direction should be set so that no living organisms can be present in the gaps between each millimeter-wave sensor 7. This distance between centers is, for example, approximately 400 mm.

With this configuration, at least one of the forward millimeter-wave sensors 12A emits millimeter waves 7 through the front windshield of the vehicle 4 to detect living organisms (people or animals) inside the vehicle.
The number of forward millimeter-wave sensors 12A may be one or more, as long as they can irradiate millimeter waves 7 from the front of the vehicle 4 through the front windshield of the vehicle 4 and detect living organisms (people or animals) throughout the entire interior of the vehicle (front seats, middle seats, or rear seats).

Furthermore, it is preferable that the multiple (nine in this example) in-vehicle millimeter-wave sensors 12 have different transmission frequencies to prevent mutual interference.
For example, it is preferable that the transmission frequencies be different from each other within the 24 GHz band range of 24.0 to 24.25 GHz.
With this configuration, the multiple millimeter waves 7 emitted by the multiple in-vehicle millimeter wave sensors 12 are not limited to being parallel to each other, but may, for example, intersect with each other.

The vehicle body millimeter-wave sensor 12C detects the shaking of the vehicle 4 by irradiating a part of the vehicle 4, excluding the front windshield, with millimeter waves 7 from the front.
In this example, one vehicle body millimeter-wave sensor 12C is positioned at the center of height h0. Height h0 is set to accommodate multiple vehicle types and to ensure reliable detection of the vehicle 4.

The rear-facing millimeter-wave sensor 12D emits millimeter waves 7 onto the vehicle 4 from the front outside of the boarding/alighting area 5 to detect vibrations at the rear of the boarding/alighting area (for example, the entrance/exit door 3).
In this example, the two rear-facing millimeter-wave sensors 12D are located on the outside in the width direction of the boarding/alighting area 5 and are set at a height opposite the entrance/exit door 3.
The half-power angle θ and irradiation angle α of the vehicle body millimeter-wave sensor 12C and the rear millimeter-wave sensor 12D may differ from those of the front millimeter-wave sensor 12A.

As mentioned above, millimeter-wave sensors can detect living organisms through the Doppler effect. However, because millimeter-wave sensors have high detection sensitivity, capable of detecting chest movements during breathing and heartbeats, they may falsely detect the shaking of the vehicle 4 after it has stopped, or the movement of the doors (due to opening/closing or wind, etc.).

The vehicle body millimeter-wave sensor 12C and the rear millimeter-wave sensor 12D are provided to prevent this false detection.
In other words, the reflected wave data from the vehicle body millimeter-wave sensor 12C is used to remove the vibration component of the vehicle 4 from the reflected wave data from the in-vehicle millimeter-wave sensor 12.
Furthermore, the reflected wave data from the rear-facing millimeter-wave sensor 12D is used to remove the vibration component from the rear (e.g., the entrance/exit door 3) from the reflected wave data from the in-vehicle millimeter-wave sensor 12.

Furthermore, if the anti-reflective device 20 and vibration damping device 30 are sufficiently effective, one or both of the vehicle body millimeter-wave sensor 12C and the rear-facing millimeter-wave sensor 12D may be omitted.

In Figure 3(B), three lateral millimeter-wave sensors 12B are positioned at a height h4, spaced apart along the length of the vehicle. The height h4 is set to accommodate the rear seats of multiple vehicle types.
Note that the half-power angle θ and irradiation angle α of the side millimeter-wave sensor 12B may differ from those of the front millimeter-wave sensor 12A.
With this configuration, at least one of the side millimeter-wave sensors 12B irradiates millimeter waves 7 into the interior through the side glass of the vehicle, and detects living organisms (people or animals) inside the vehicle.

The number of side millimeter-wave sensors 12B can be one or two or more, as long as they can detect living beings (people or animals) in the rear seats by irradiating millimeter waves 7 from the side of the boarding/alighting area 5 through the side glass of the vehicle.
Furthermore, the detection of living organisms by the lateral millimeter-wave sensor 12B is not limited to the rear seats, but may also be performed in the front seats, middle seats, or luggage compartment.

Figure 4 is an overall configuration diagram of the in-vehicle biological detection device 10.
In Figure 4(A), the in-vehicle millimeter-wave sensor 12 includes an oscillator 13a that emits millimeter waves 7 and a parabolic antenna 13b that irradiates vertically polarized millimeter waves 7. The parabolic antenna 13b is a bowl-shaped antenna that uses a rotating paraboloid as a reflector for radio waves.
Furthermore, the present invention is not limited to parabolic antennas, and high-gain patch array antennas may also be used. Additionally, beamforming technology using array antennas may be utilized.

The transmission frequency for millimeter wave 7 is preferably in the 24 GHz band.
The reason for using millimeter wave 7 in the 24 GHz band is that conventional millimeter waves in the 10 GHz band cannot be used with doors (or shutters) open due to indoor regulations under the Radio Law. In contrast, there are no indoor regulations for the 24 GHz band (quasi-millimeter wave). In this invention, quasi-millimeter waves in the 24 GHz band are simply referred to as "millimeter wave 7".
Furthermore, the millimeter wave 7 of the present invention is not limited to millimeter waves in the 24 GHz band, but may also be in the 79 GHz band, or radio waves in the frequency band of 10 to 80 GHz.

Furthermore, vertical polarization (TM waves) is used because it has a higher transmittance through glass compared to conventional horizontal polarization (TE waves).
Furthermore, the parabolic antenna 13b is used because, compared to conventional patch antennas, it allows for increased antenna gain while narrowing the half-power angle θ.

As shown in Figure 1, the parabolic antenna 13b should have a half-power angle θ of 6 degrees or more and 10 degrees or less at which the antenna gain is halved, and a half-power width L at 3 m from the irradiation position should be 300 mm or more and 600 mm or less.
The half-power angle θ is the divergence angle of millimeter-wave 7 at which the antenna gain is halved. When the half-power angle is between 6 and 10°, the half-power width L (illumination width of millimeter-wave 7) at 3m from the irradiation position will be between 300mm and 600mm.

Figure 4(B) shows the relationship between the amplification factor of the intermediate frequency amplifier 14 (vertical axis) and the frequency of the reflected wave data 8 (horizontal axis).
As shown in this figure, the intermediate frequency amplifier 14 amplifies the frequency components of respiration, pulse, and body movement from the reflected wave data 8 with different amplification factors and outputs an amplified signal 9.

The displacement of a person's pulse is on the order of approximately 0.1 to 0.2 mm, the displacement of respiration is on the order of approximately 10 mm, and the displacement of body movement is on the order of approximately 100 mm. Furthermore, in the radar cross section (RCS), if the pulse is set to 1, respiration is on the order of 100, and body movement is on the order of 1000.
Therefore, the RCS of respiration and body movement are two to three orders of magnitude larger than that of pulse, and when detecting vital signals (biological signals) with a millimeter-wave sensor, the pulse signal component is masked by the signal components of respiration and body movement. In addition, in order to detect the pulse signal, it is necessary to amplify the signal using a high-gain amplifier, but in this case, it is predicted that the amplifier will be saturated by the signals of respiration and body movement, and the pulse signal will be lost.

On the other hand, the frequency components of vital signals are, for example, approximately 0.2 to 0.5 Hz for respiration, approximately 1 to 2 Hz for pulse, and approximately 5 Hz or higher for body movement.
In this invention, as shown in Figure 4(B), the frequency components of respiration, pulse, and body movement are amplified with different amplification factors.

In this example, the amplification factor for the 0.5 Hz to 5 Hz range, which includes the pulse (approximately 1 to 2 Hz), is set to a high gain G (=X) necessary for detecting the pulse signal. The amplification factor for the approximately 0.2 to 0.5 Hz range, corresponding to respiration, is set to a gain G (e.g., =X-20 dB) so that the amplifier does not saturate and an amplified signal 9 of the same order as the pulse signal is obtained. Similarly, the amplification factor for the 5 to 20 Hz range, corresponding to body movement, is set to a gain G (e.g., =X-40 dB) so that the amplifier does not saturate and an amplified signal 9 of the same order as the pulse signal is obtained.
Furthermore, this amplification characteristic is essentially synonymous with a bandpass filter. Also, the shoulder characteristics of the bandpass filter do not need to be steep; they can change smoothly.

The above configuration allows for the amplification of respiration, pulse, and body movement signals so that each signal is not overwhelmed by the others and the amplifier does not become saturated, enabling the detection of each vital signal.

In Figure 4(A), the discrimination device 16 includes a frequency analyzer 17 and a comparison unit 18.
The frequency analyzer 17 performs frequency analysis on the amplified signal 9. The comparison unit 18 compares the output of the frequency components of respiration, pulse, and body movement after frequency analysis with their respective thresholds.
This configuration allows for the detection of a living organism by comparing the frequency components of respiration, pulse, and body movement (for example, approximately 0.2–0.5 Hz, approximately 1–2 Hz, and approximately 5 Hz or higher) with their respective thresholds, and determining whether any of the outputs exceed the threshold.

In Figures 1 and 2, the in-vehicle biological detection device 10 further includes an anti-reflective device 20 and a vibration damping device 30.

The anti-reflective device 20 prevents the reflection of millimeter waves 7 on the outside of the vehicle 4.
In this example, the anti-reflective device 20 faces the forward millimeter-wave sensor 12A with the boarding/alighting area 5 in between, and has an intermediate door 22 located between the entrance/exit door 3 through which the vehicle 4 enters and exits and the boarding/alighting area 5.

The intermediate door 22 is configured to open and close between an open position and a closed position. The opening and closing mechanism of the intermediate door 22 is, for example, vertical movement, but it may also be horizontal movement or any other structure.
The intermediate door 22 allows the vehicle 4 to pass between the entry/exit door 3 and the boarding/alighting area 5 when it is open, and shields the vehicle from millimeter waves 7 that would otherwise hit the entry/exit door 3 when it is closed. The total height of the intermediate door 22 when it is closed should be equal to or greater than the total height of the vehicle 4.

Furthermore, the intermediate door 22 is mounted in a position where millimeter waves 7 are irradiated when it is in the closed position and has a first radio wave absorber 19A that absorbs millimeter waves 7.

In Figure 2, the anti-reflective device 20 further has an upper door 24 located above the vehicle 4 in the boarding/alighting area 5.
The upper door 24 is preferably positioned above and in front of the front glass of the vehicle 4 so that the millimeter waves 7 reflected by the front glass are not reflected to the forward millimeter wave sensor 12A.
The upper door 24 is also attached to the side facing the vehicle 4 and has a second radio wave absorber 19B that absorbs millimeter waves 7.

In Figure 1, the anti-reflection device 20 further includes a wall plate 26 facing the lateral millimeter-wave sensor 12B with the boarding/alighting area 5 in between, and a third radio wave absorber 19C attached to the wall plate 26 that absorbs millimeter waves 7.

It is preferable that the intermediate door 22, the upper door 24, and the wall panel 26 have rigidity that prevents vibration within the vital signal frequency range, even when strong winds are blowing around the building and wind is blowing into the warehouse while the entrance/exit doors are closed.
Furthermore, the wall panel 26 should be installed in a manner that does not affect the vibrations of the inner wall 2a. Alternatively, the wall panel 26 may be omitted, and the third radio wave absorber 19C may be installed directly on the inner wall 2a.

The first radio wave absorber 19A, the second radio wave absorber 19B, and the third radio wave absorber 19C are preferably made of foamed urethane impregnated with a dielectric coating, and are designed to exhibit particularly high performance in millimeter waves depending on the shape and arrangement of the peaks and the fineness of the pitch.
These materials may differ even if they are the same type of radio wave absorber.

Furthermore, radio wave absorbers may be applied to the lining of the five interior surfaces other than the floor. This allows for the suppression of multipath interference within the storage area, even when using radio waves in frequency bands with high reflectivity on glass surfaces (e.g., the 79 GHz band).

In Figures 1 and 2, the pallet 6 is supported at both ends in its longitudinal direction within the boarding/alighting area 5. The vibration damping device 30 has the function of changing the vibration mode of the pallet 6 on which the vehicle 4 is placed, thereby changing the vibration frequency distribution of the vehicle 4.

In this example, the vibration damping device 30 maintains support at both ends while supporting the pallet 6 at the center of its length or at multiple points spaced apart along its length, thereby changing the vibration mode of the pallet 6 to a second or third order or higher.

The vibration damping device 30 is, for example, a plurality of jack devices 32. Each plurality of jack devices 32 has a support portion 32a and a drive portion 32b, and is installed in a pit located at the bottom of the access area 5. The support portion 32a is movable up and down within the pit, supporting the lower part of the pallet 6 to prevent vibration in the raised position, and retracting to a position that does not affect the movement of the pallet 6 in the lowered position. The drive portion 32b is, for example, electrically operated, and raises and lowers the support portion 32a via a link or screw.

Figure 8 is an explanatory diagram of the vibration modes of a simply supported beam. In this figure, △ indicates the support position, and I indicates the order of the vibration mode.
When the pallet 6 is supported only at both ends in the longitudinal direction, the vibration modes are predominantly first-order modes (I=1), with the amplitude being greatest in the central part. In this case, higher-order modes of I=2 or higher are also included.

Furthermore, when the center of a simply supported beam is supported, the amplitude at both ends and the center becomes zero. Therefore, the first-mode vibration is suppressed, and the second-mode vibration (I=2) becomes dominant, with the amplitude being maximum at the midpoint of the support point. The natural frequency of the second-mode is 2 × 2 = 4 times that of the first-mode, and the maximum amplitude is also significantly reduced.

Furthermore, if the beam is supported at points 1/3 and 2/3 of the way from both ends, the amplitude at the four points including the ends becomes zero. Therefore, the first and second modes of vibration are suppressed, and the third mode (I=3) becomes dominant. In this case, the amplitude is maximum at the midpoint of each support point, the natural frequency of the third mode is 3 × 3 = 9 times that of the first mode, and the maximum amplitude is even smaller.

Furthermore, by increasing the number of support points, the vibration mode I of the pallet 6 on which the vehicle 4 is placed can be artificially changed to a higher-order vibration mode of a double-ended support beam.
Therefore, by supporting the pallet 6 at its center in the longitudinal direction or at multiple points spaced apart in the longitudinal direction, the vibration mode I of the pallet 6 can be changed to a second-order or third-order or higher mode, thereby changing the vibration frequency distribution of the vehicle 4 placed on it.

Figure 5 is an overall flowchart of the in-vehicle biological detection method of the present invention.
The present invention's method for detecting living organisms inside a vehicle uses the above-described in-vehicle living organism detection device 10 to detect living organisms inside the vehicle by irradiating the vehicle 4 with millimeter waves 7. In this figure, the in-vehicle living organism detection method has steps (processes) S1 to S5.

In step S1, the anti-reflective device 20 prevents the reflection of millimeter waves 7 on the outside of the vehicle 4. That is, the intermediate door 22, upper door 24, and wall panel 26 described above are installed in advance. The intermediate door 22 is moved to the closed position after the vehicle 4 is placed on the pallet 6.
In step S2, the vibration damping device 30 changes the vibration mode of the pallet 6 on which the vehicle 4 is placed to a higher order, thereby changing the vibration frequency distribution of the vehicle 4. This state is maintained until step S4 or step S5.

Step S3 is performed after the person has disembarked from vehicle 4 and exited the depot, and after the entrance/exit doors 3 have been fully closed.
In step S3, millimeter waves 7 are irradiated into the vehicle 4 placed on the pallet 6 through its windows, and the reflected wave data 8 is received. It is preferable to use the front millimeter wave sensor 12A, the side millimeter wave sensor 12B, the vehicle body millimeter wave sensor 12C, and the rear millimeter wave sensor 12D simultaneously.

In step S4, the frequency components of respiration, pulse, and body movement from the reflected wave data 8 are amplified at different amplification rates and an amplified signal 9 is output.
In this process, the reflected wave data 8 from the vehicle body millimeter-wave sensor 12C is removed from the reflected wave data 8 from the front millimeter-wave sensor 12A to cancel out the vibration component of the vehicle 4. Additionally, the reflected wave data 8 from the rear millimeter-wave sensor 12D is removed from the reflected wave data 8 from the front millimeter-wave sensor 12A to cancel out the vibration component from the rear (e.g., the entrance/exit door 3).
Similarly, it is preferable that the reflected wave data 8 from the lateral millimeter-wave sensor 12B also cancels out the vibration component of the vehicle 4.
Note that this removal (cancellation) can be performed either before or after amplification.
In step S5, the presence or absence of living organisms is determined from the amplified signal 9.

Figure 6 shows the test results demonstrating the effect of the intermediate door 22.
In this test, the entry/exit door 3 was vibrated at approximately 1 Hz, and the output (frequency analysis results) of the frequency analyzer 17 was compared.
Figure 6(A) shows the case without the intermediate door 22, and Figure 6(B) shows the case with the intermediate door 22. In Figures 6(A) and (B), the horizontal axis is frequency, and the vertical axis is output level. The solid line in the figure represents the I signal (real part) of the IQ signal obtained from the quadrature mixer of the parabolic antenna 13b, and the dashed line represents the Q signal (imaginary part). Due to the principle of the quadrature mixer, if only one signal is considered, some signals will be missed, so both signals are evaluated.
A comparison of Figure 6(A) and (B) shows that by installing the intermediate door 22, even if the entry/exit door 3 vibrates at approximately 1 Hz, the output levels of the I and Q signals obtained from the quadrature mixer can be significantly reduced compared to when the intermediate door 22 is not installed.

Figure 7 shows the test results demonstrating the effectiveness of the vibration damping device 30.
In this test, the output of the frequency analyzer 17 was compared by supporting the center of the underside of the pallet 6, which was supported at both ends, from below.
Figures 7(A) and (B) show the case of a "foldable pallet" with relatively low rigidity, while (C) shows the case of a "flat pallet" with relatively high rigidity.
Furthermore, (A) and (C) are cases where the center of the bottom surface is not supported, while (B) is a case where the center of the bottom surface is supported.

In Figures 7(A), (B), and (C), the horizontal axis represents frequency and the vertical axis represents output level. The solid lines in the figures represent the I signal obtained from the quadrature mixer of the parabolic antenna 13b, and the dashed lines represent the Q signal.
In the case of a highly rigid "flat pallet," the output level near 1 Hz included in the output signal in Figure 7(C) is low, and it can be concluded that the possibility of falsely detecting a living organism from this signal is low.
On the other hand, in the case of a "foldable pallet" with low rigidity, the output level near 1 Hz included in the output signal in Figure 7(A) was high, and there was a possibility of false detection of living organisms from this signal.
In contrast, even with a "folding pallet," the output level near 1 Hz included in the output signal in Figure 7(B) is low, and it can be determined that the possibility of falsely detecting a living organism from this signal is low.

According to the embodiment of the present invention described above, the intermediate frequency amplifier 14 amplifies the frequency components of respiration, pulse, and body movement from the reflected wave data 8 with different amplification factors and outputs an amplified signal 9. Therefore, each vital signal can be detected without being masked by others, ensuring reliable detection of living organisms inside the vehicle.

Furthermore, since the anti-reflective device 20 prevents the reflection of millimeter waves 7 on the outside of the vehicle 4, the influence of noise caused by diffuse reflection from objects on the outside of the vehicle 4 can be reduced, even when there is wind blowing in.

Furthermore, the vibration damping device 30 changes the vibration mode I of the pallet 6 on which the vehicle 4 is placed to a higher order, thereby changing the vibration frequency distribution of the vehicle 4. This allows for the reduction of the impact of wind by altering the magnitude and frequency range of noise caused by the vibration of the vehicle 4.

Therefore, even in the presence of wind, the system can reduce the influence of noise from non-living objects, allowing for reliable detection of living organisms inside the vehicle by detecting signals from respiration, pulse, and body movement without them being masked by each other.

It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention.

α: irradiation angle, θ: half-power angle, L: half-power width,
1. Mechanical parking system, 2. Passenger compartment, 2a. Interior wall, 3. Entrance/exit door,
4. Vehicle, 5. Boarding/Alighting Area, 6. Pallet, 7. Millimeter Wave, 8. Reflected Wave Data
9. Amplified signal, 10. In-vehicle biological detection device, 12. In-vehicle millimeter-wave sensor,
12A Forward millimeter-wave sensor, 12B Side millimeter-wave sensor,
12C Millimeter-wave sensor for vehicle body, 12D Millimeter-wave sensor for rear,
13a Oscillator, 13b Parabolic antenna, 14 Intermediate frequency amplifier,
16. Discrimination device, 17. Frequency analyzer, 18. Comparison unit,
19A First radio wave absorber, 19B Second radio wave absorber, 19C Third radio wave absorber,
20 Anti-reflective device, 22 Middle door, 24 Upper door, 26 Wall panel,
30. Vibration damping device

Claims (8)

A vehicle-in-vehicle biological detection device that detects living organisms inside a vehicle by irradiating a vehicle parked in the boarding/alighting area of a storage vehicle with millimeter waves,
An anti-reflective device for preventing the reflection of millimeter waves in the space surrounding the vehicle,
A millimeter-wave sensor for use inside a vehicle that irradiates the interior of the vehicle with millimeter waves through its window glass and receives the reflected wave data,
An intermediate frequency amplifier that amplifies the frequency components of respiration, pulse, and body movement from the reflected wave data with different amplification factors and outputs an amplified signal,
A discrimination device that determines the presence or absence of the living organism from the amplified signal,
An in-vehicle biological detection device comprising : a vibration damping device that changes the vibration mode of the pallet on which the vehicle is placed to a higher order, thereby changing the vibration frequency distribution of the vehicle . The pallet is supported at both ends in the longitudinal direction within the boarding/alighting area.
The in-vehicle biological detection device according to claim 1 , wherein the vibration damping device supports the pallet at the center in the longitudinal direction of the pallet or at multiple locations spaced apart in the longitudinal direction, while maintaining support at both ends. The aforementioned in-vehicle millimeter-wave sensor includes a forward-facing millimeter-wave sensor that irradiates the vehicle with millimeter waves from the front through the windshield,
The in-vehicle biological detection device according to claim 1, further comprising a side millimeter-wave sensor that irradiates the vehicle with millimeter waves from the side through the side glass of the vehicle. The anti-reflective device is
The vehicle has an intermediate door located between the entry/exit door and the entry/exit door, which the vehicle uses to enter and exit, and the entry/exit area, with the entry/exit area in between, and facing the forward millimeter-wave sensor.
The intermediate door is openable and closable between an open position that allows the vehicle to pass between the entry/exit door and the boarding/alighting area, and a closed position that shields the millimeter waves irradiated onto the entry/exit door.
The in-vehicle biological detection device according to claim 3 , further comprising a first radio wave absorber that is attached to a position where the millimeter waves are irradiated in the closed position and absorbs the millimeter waves. The anti-reflective device is
The boarding/alighting area has an upper door located above the vehicle,
The in-vehicle biological detection device according to claim 4 , wherein the upper door is attached to the surface facing the vehicle and has a second radio wave absorber that absorbs millimeter waves. The anti-reflective device is
The in-vehicle biological detection device according to claim 3 , comprising a wall plate facing the lateral millimeter-wave sensor with the boarding/alighting area in between, and a third radio wave absorber attached to the wall plate for absorbing the millimeter waves. A millimeter-wave sensor for a vehicle body detects the shaking of the vehicle by irradiating a part of the vehicle, excluding the windshield, with the millimeter waves from the front.
The vehicle is equipped with a rear-facing millimeter-wave sensor that irradiates the vehicle with millimeter waves from the front outside the boarding/alighting area to detect vibrations on the rear of the vehicle behind the boarding/alighting area.
The in-vehicle biological detection device according to claim 1, wherein the intermediate frequency amplifier removes the reflected wave data of the vehicle body millimeter wave sensor or the in-vehicle millimeter wave sensor from the reflected wave data of the in-vehicle millimeter wave sensor. A method for detecting living organisms inside a vehicle by irradiating a vehicle parked in the boarding/alighting area of a storage facility with millimeter waves,
(A) The reflection of the millimeter waves in the space surrounding the vehicle is prevented by an anti-reflective device,
(B) The vibration mode of the pallet on which the vehicle is placed is changed to a higher order by the vibration damping device, thereby changing the vibration frequency distribution of the vehicle.
(C) The vehicle placed on the pallet is irradiated with the millimeter waves into the vehicle through its window glass and the reflected wave data is received.
(D) The frequency components of respiration, pulse, and body movement from the reflected wave data are amplified at different amplification rates and an amplified signal is output.
(E) A method for detecting a living organism inside a vehicle, which determines the presence or absence of the living organism from the amplified signal.