JP7422334B2 - Signal processing device and sensor system - Google Patents

Description

The present disclosure relates to a signal processing device and a sensor system.

The vehicle interior situation detection device disclosed in Patent Document 1 uses an infrared sensor to detect the interior situation of the vehicle interior, such as the passenger status inside the vehicle. The vehicle interior situation detection device includes an actuator that changes at least one of the direction or position of the infrared sensor, and a drive control means that drives the actuator, in order to change the detection area by the infrared sensor. The drive control means adjusts the detection area based on at least one of the sliding position of the seat, the height of the seat, and the reclining angle of the seat.

Japanese Patent Application Publication No. 10-119710

The vehicle interior situation detection device (sensor system) of Patent Document 1 includes an actuator to change the detection area (monitoring area) of the sensor, and the number of parts increases and the configuration becomes complicated.

Therefore, an object of the present disclosure is to provide a signal processing device and a sensor system that have a simple configuration and can change the monitoring area depending on the state of the seat.

A signal processing device according to one aspect of the present disclosure includes a first acquisition section, a second acquisition section, a determination section, and a region setting section. The first acquisition unit receives a radio wave sensor signal output from a radio wave sensor that receives reflected waves of electromagnetic waves radiated into a predetermined space. The second acquisition unit receives a seat sensor signal output from a seat sensor that detects a state of a seat within the predetermined space. The determination unit performs determination processing to determine the state of a person within the predetermined space based on the radio wave sensor signal. The area setting unit sets a monitoring area in which the determination process is performed in the predetermined space based on the seat sensor signal. The determination unit performs the determination process using some of the reflected waves that are reflected at the monitoring area.

A sensor system according to one aspect of the present disclosure includes the above-described signal processing device and the radio wave sensor.

As described above, the present disclosure has the advantage of being able to change the monitoring area depending on the state of the seat with a simple configuration.

FIG. 1 is a plan view schematically showing a vehicle equipped with a sensor system according to an embodiment. FIG. 2 is a block diagram showing the same sensor system as above. FIG. 3 is a diagram for explaining the operation of the radio wave sensor included in the sensor system. FIG. 4 is a perspective view for explaining setting of a monitoring area by a signal processing device included in the sensor system. FIG. 5 is a block diagram showing the signal processing device same as above. FIG. 6 is a side view for explaining setting of a monitoring area by the signal processing device same as above. FIG. 7 is another side view for explaining setting of a monitoring area by the signal processing device same as above. FIG. 8 is a diagram for explaining determination processing by the signal processing device same as above. FIG. 9 is a schematic diagram showing a virtual antenna of a radio wave sensor included in the above sensor system. FIG. 10 is a plan view showing a monitoring area set in the cabin of the same vehicle. FIG. 11 is another diagram for explaining the determination process by the signal processing device same as above.

The following embodiments generally relate to signal processing devices and sensor systems. More specifically, the present invention relates to a signal processing device and a sensor system using a radio wave sensor. Note that the embodiment described below is only an example of the embodiment of the present disclosure. The present disclosure is not limited to the following embodiments, and various changes can be made depending on the design etc. as long as the effects of the present disclosure can be achieved.

(Embodiment)
(1) Overview of sensor system FIG. 1 shows a vehicle 9 equipped with a sensor system 1 of this embodiment. The vehicle 9 is, for example, a passenger car that includes a vehicle body 90 in which a plurality of passengers can ride. In FIG. 1, a virtual width axis X along the width of the vehicle 9, a virtual length axis Y along the length of the vehicle 9, and a virtual height axis Z along the height of the vehicle 9. is also written on vehicle 9. Of the two directions that are opposite to each other along the width axis X, one is to the left and the other is to the right. Of the two mutually opposite directions along the length axis Y, one will be the anterior direction and the other will be the posterior direction. Of the two directions that are opposite to each other along the height axis Z, one is upward and the other is downward. The above-mentioned left direction, right direction, front direction, rear direction, upward direction, and downward direction are defined based on the person sitting in the seat of the vehicle 9 and looking ahead. Note that the vehicle 9 is not limited to a passenger car, and may be any vehicle that transports people, baggage, or goods.

A cabin 91 of the vehicle 9 corresponds to a predetermined space in the present disclosure, and a plurality of seats 8 are installed in the cabin 91. The plurality of seats 8 are two front seats 81 and 82, two second row seats 83 and 84, and two third row seats 85 and 86. Specifically, front seats 81 and 82 are arranged side by side on the left and right in the front part of the vehicle interior 91, and two second row seats 83 and 84 are arranged side by side on the left and right in the middle of the vehicle interior 91. At the rear of the compartment 91, two third row seats 85 and 86 are arranged side by side on the left and right. The front seat 81 is a driver's seat, and the front seat 82 is a passenger seat.

The sensor system 1 includes a radio wave sensor 2, a seat sensor 3, a signal processing device 4, and a data analysis device 5, as shown in FIGS. 1 and 2. The signal processing device 4 performs a determination process to determine the state of the person inside the vehicle interior 91 . The data analysis device 5 performs various types of monitoring and control in the vehicle 9 based on the determination results of the signal processing device 4.

(2) Radio Wave Sensor The radio wave sensor 2 of this embodiment is installed near the ceiling of the vehicle interior 91 at the center of the front end of the vehicle interior 91. The radio wave sensor 2 may be configured integrally with a rearview mirror of the vehicle 9, for example. The radio wave sensor 2 transmits a radio wave (electromagnetic wave) as a transmission wave from the front side of the vehicle interior 91 toward the rear diagonally downward, and receives the radio wave reflected by an object in the vehicle interior 91 as a reflected wave. A radio wave sensor signal J1 including information regarding the distance from to the object is output.

The radio wave sensor 2 is, for example, a MIMO (Multiple Input Multiple Output) type radio wave sensor using the FMCW (Frequency-Modulated Continuous-Wave) method.

An FMCW radio wave sensor transmits a transmission wave (chirp signal) whose frequency (transmission frequency) changes over time, and receives a reflected wave whose frequency (reception frequency) changes over time. . The FMCW radio wave sensor generates a beat signal having a frequency (beat frequency) equal to the frequency difference between the transmission frequency and the reception frequency as a radio wave sensor signal. The beat frequency depends on the distance from the radio wave sensor 2 to the object, and the distance from the radio wave sensor to the object can be determined based on the beat frequency.

Specifically, the FMCW radio wave sensor repeats a sweep process in which the transmission frequency is raised and then lowered. In the sweep process, the transmission frequency increases by the sweep frequency width Δfa during the sweep time Ta. Assuming that the distance from the radio wave sensor to the object is D and the speed of light is C, the radio wave sensor receives the reflected wave after a time of 2D/C after the transmission wave is transmitted. The reception frequency, which is the frequency of the reflected wave, changes over time like the transmission frequency. Then, the radio wave sensor generates a beat signal with a frequency fb equal to the frequency difference between the transmission frequency and the reception frequency, and outputs it as a radio wave sensor signal. The frequency fb of the beat signal is fb=[(Δfa·2D)/(C·Ta)]. Therefore, the distance D to the object is expressed as D=(fb·C·Ta)/(2·Δfa).

A MIMO type radio wave sensor includes multiple transmitters and multiple receivers. The plurality of transmitters each transmit transmission waves exclusively in a predetermined order. The plurality of receivers receive reflected waves in synchronization with each transmission period of the plurality of transmitters. As a result, a number of virtual antennas equal to the product of the number of transmitters and the number of receivers are configured, and the same number of channels as the number of virtual antennas are formed in the radio wave sensor signal. As the number of virtual antennas increases, the aperture area of the antenna of the radio wave sensor increases, and the spatial resolution improves.

In FIG. 2, the radio wave sensor 2 includes a first transmitter 21a and a second transmitter 21b as two transmitters, and a first receiver 22a and a second receiver 22b as two receivers. In this case, the number of virtual antennas is four, and the radio wave sensor signal J1 becomes a signal having four channels.

Specifically, when the transmission frequency of the first transmitter 21a is f1, the first transmitter 21a raises the transmission frequency f1 over the sweep time Ta1 and then lowers it, as shown in the first stage of FIG. By repeating the sweep process, the chirp signal CS1 is transmitted every transmission period T0. Assuming that the transmission frequency of the second transmitter 21b is f2, the second transmitter 21b repeats a sweep process in which the transmission frequency f2 is raised over the sweep time Ta2 and then lowered, as shown in the second stage of FIG. As a result, the chirp signal CS2 is transmitted every transmission period T0. Note that the transmission period T0 is equal to the sum of the sweep time Ta1 and the sweep time Ta2.

As shown in the third stage of FIG. 3, the first receiver 22a receives the reflected wave of the chirp signal CS1 as a reflected wave of channel CH1, and receives the reflected wave of chirp signal CS2 as a reflected wave of channel CH3. do. As shown in the fourth stage of FIG. 3, the second receiver 22b receives the reflected wave of the chirp signal CS1 as a reflected wave of channel CH2, and receives the reflected wave of chirp signal CS2 as a reflected wave of channel CH4.

Radio wave sensor 2 generates each beat signal of channels CH1 to CH4 using each reflected wave of channels CH1 to CH4, and outputs a signal containing information of each beat signal of channels CH1 to CH4 as radio wave sensor signal J1. do. The radio wave sensor signal J1 is an IQ signal consisting of an in-phase component and a quadrature component, an I signal consisting of an in-phase component, or the magnitude of an IQ signal.

(3) Seat Sensor The seat sensor 3 detects the state of the seat 8. Preferably, the state of the seat 8 includes at least one of the shape of the seat 8 and the position of the seat 8. In this embodiment, the shape of the seat 8 is exemplified by the amount of reclining of the seat 8 (the inclination of the backrest 8b), and the position of the seat 8 is exemplified by the amount of sliding of the seat 8 (the position of the seat 8 in the longitudinal direction).

Specifically, as shown in FIG. 4, the seat 8 includes a seat surface 8a and a backrest 8b, and the backrest 8b is attached to the rear end of the seat surface 8a. A rail extending along the length axis Y is fixed to the floor surface of the vehicle compartment 91, and the seat surface 8a is attached to a slider that is movable in the front-rear direction along the rail. That is, the seat 8 is configured to be movable in the longitudinal direction along the length axis Y. The backrest 8b is configured to be rotatable around a rotation axis extending in the left-right direction. Therefore, a person can arbitrarily adjust the longitudinal position (sliding amount) of the seat 8 and the rotation angle (reclining amount) of the backrest 8b. For example, if the seat 8 is a power seat, the seat 8 is moved forward and backward by the driving force of the slide motor, and the backrest 8b is rotated by the driving force of the reclining motor.

Therefore, the seat sensor 3 includes a first position sensor 31 and a second position sensor 32, as shown in FIGS. 2 and 4.

The first position sensor 31 is a position sensor that outputs a first seat sensor signal J21 according to the position of the seat 8 in the longitudinal direction. The first seat sensor signal J21 is an electrical signal representing a value using an analog value, a digital value, or the number of pulses, and the value represented by the first seat sensor signal J21 is the first sensor value Vs. The first sensor value Vs increases as the seat 8 moves backward.

The second position sensor 32 is a position sensor that outputs a second seat sensor signal J22 according to the rotation angle φr (see FIG. 4) of the backrest 8b. The rotation angle φr is 0 degrees when the backrest 8b stands upright in the direction extending along the height axis Z. If the backrest 8b rotates in a direction away from the seat surface 8a (backward), the rotation angle φr increases, and if the backrest 8b rotates in a direction toward the seat surface 8a (forward), the rotation angle φr decreases. The second seat sensor signal J22 is an electrical signal representing a value using an analog value, a digital value, or the number of pulses, and the value represented by the second seat sensor signal J22 is the second sensor value Vr. The second sensor value Vr increases as the backrest 8b rotates backward and the rotation angle φr increases.

(4) Signal Processing Device The signal processing device 4 includes a first acquisition section 41, a second acquisition section 42, and a signal processing section 43, as shown in FIG.

It is preferable that the signal processing device 4 of the present disclosure includes a computer system. A computer system mainly consists of a processor and a memory as hardware. At least part of the function of the signal processing unit 43 in the present disclosure is realized by the processor executing a program recorded in the memory of the computer system. The program may be pre-recorded in the memory of the computer system, may be provided through a telecommunications line, or may be recorded on a non-transitory storage medium readable by the computer system, such as a memory card, optical disc, hard disk drive, etc. may be provided. A processor of a computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The integrated circuits such as IC or LSI referred to herein have different names depending on the degree of integration, and include integrated circuits called system LSI, VLSI (Very Large Scale Integration), or ULSI (Ultra Large Scale Integration). Furthermore, an FPGA (Field-Programmable Gate Array), which is programmed after the LSI is manufactured, or a logic device that can reconfigure the connections inside the LSI or reconfigure the circuit sections inside the LSI, may also be used as a processor. Can be done. The plurality of electronic circuits may be integrated into one chip, or may be provided in a distributed manner over a plurality of chips. A plurality of chips may be integrated into one device, or may be distributed and provided in a plurality of devices. A computer system herein includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

Further, the computer system may be a system composed of one or more computers. For example, at least some of the functions of the determination unit 431, area setting unit 432, and communication unit 433, which will be described later, may be realized by a cloud (cloud computing).

The first acquisition unit 41 has an interface function to receive the radio wave sensor signal Y1 from the radio wave sensor 2.

The second acquisition unit 42 has an interface function to receive the first seat sensor signal J21 and the second seat sensor signal J22 from the seat sensor 3.

The signal processing section 43 includes a determination section 431, a region setting section 432, a communication section 433, and a storage section 434. The determination unit 431 performs determination processing to determine the state of the person inside the vehicle compartment 91 based on the radio wave sensor signal J1. The area setting unit 432 sets the monitoring area 7 (see FIG. 1) in the vehicle interior 91 where the determination unit 431 performs determination processing based on the first seat sensor signal J21 and the second seat sensor signal J22. The determination unit 431 performs determination processing using some of the reflected waves that are reflected at the monitoring area 7 . The storage unit 434 stores various data.

(4.1) Storage Unit The storage unit 434 stores in advance initial data, coefficient data, relative coordinate data of the monitoring area 7, height data of the monitoring area 7, etc. used by the area setting unit 432.

(4.1.1) Initial Data The initial data is each data of slide offset Vs0, reclining offset Vr0, and reference position (sx, sy).

The slide offset Vs0 is the first sensor value Vs when the seat 8 is located furthest forward, and is the minimum value of the first sensor values Vs. The storage unit 434 stores the first sensor value Vs when the seat 8 is operated so that the seat surface 8a is positioned furthest forward as the slide offset Vs0.

The reclining offset Vr0 is the second sensor value Vr when the rotation angle φr of the backrest 8b is 0 degrees. The storage unit 434 stores the second sensor value Vr when the seat 8 is operated so that the backrest 8b stands upright with respect to the seat surface 8a, as the reclining offset Vr0.

Let the coordinates (X, Y) in the XY plane defined by the width axis X and the length axis Y be absolute coordinates. In this embodiment, the position of the seat 8 within the vehicle interior 91 is expressed in absolute coordinates. Specifically, the absolute coordinates of the seat reference point Q, which is the reference point of the seat 8, are taken as the absolute coordinates of the seat 8. The seat reference point Q is set at the center of the seat surface 8a in the vertical direction (thickness direction) and at the right end of the front surface of the seat surface 8a. Then, the absolute coordinates of the seat 8 moved furthest forward within the slidable range are set as the reference position (sx, sy) (see FIG. 4). The storage unit 434 stores data on predetermined reference positions (sx, sy).

(4.1.2) Coefficient data The coefficient data is each data of the first proportional coefficient αs and the second proportional coefficient αr. The first proportionality coefficient αs is used when determining the absolute coordinates of the seat 8 from the first sensor value Vs. The second proportionality coefficient αr is used when determining the rotation angle φr (absolute position in the rotational direction) of the backrest 8b from the second sensor value Vr.

(4.1.3) Relative coordinate data of the monitoring area 7 The relative coordinate data of the monitoring area 7 is the relative coordinate data of the monitoring area 7 as viewed from the seat reference point Q when the rotation angle φr of the backrest 8b is 0 degrees. It is.

Specifically, the monitoring area 7 is a rectangular area parallel to the XY plane, and includes four vertices P1, P2, P3, and P4. The relative coordinates of the monitoring area 7 are expressed as rect(dx1, dy1, dx2, dy2) using the function rect. The function rect is a function that defines a rectangular area parallel to the XY plane, and rect (dx1, dy1, dx2, dy2) is a function that defines a rectangular area parallel to the , dy2), the relative coordinates of the vertex P3 (dx2, dy1), and the relative coordinates of the vertex P4 (dx2, dy2). The relative coordinates rect (dx1, dy1, dx2, dy2) of the monitoring area 7 are predetermined so that the monitoring area 7 overlaps the person when the person sitting on the seat surface 8a leans against the backrest 8b. .

Note that (dx1+dx2)/2 is preferably located at the center of the seat 8 in the left-right direction, and (dy1+dy2)/2 is preferably located near the center of the torso of the person seated on the seat 8. Further, it is preferable that dx2-dx1 be the width dimension of the person in the left-right direction, and dy2-dy1 be the thickness dimension of the person in the front-back direction. Note that rect(dx1, dy1, dx2, dy2) is preferably defined assuming a person with a standard body shape.

(4.1.4) Height data of the monitoring area 7 The height data of the monitoring area 7 is data representing the vertical position of the monitoring area 7, and is the coordinate dz1 of the height axis Z (see Fig. 4). ).

(4.2) Area Setting Unit The setting process of the monitoring area 7 by the area setting unit 432 will be described below.

The area setting unit 432 determines the absolute coordinates rect(x1, y1, x2, y2) of the monitoring area 7. The function rect is a function that defines a rectangular area parallel to the , y2), the absolute coordinates (x2, y1) of the vertex P3, and the absolute coordinates (x2, y2) of the vertex P4.

Specifically, the area setting unit 432 sets the reference position (sx, sy) and the slide correction value bs to each relative coordinate of the vertices P1 to P4 of the monitoring area 7 represented by rect (dx1, dy1, dx2, dy2). , and the reclining correction value br, the absolute coordinates rect(x1, y1, x2, y2) are determined.

The area setting unit 432 calculates the slide correction value bs using Equation 1 below.

The region setting unit 432 calculates the reclining correction value br using Equation 2 below.

The concept of the above-mentioned arithmetic processing by the area setting unit 432 is expressed as in Equation 3.

The absolute coordinates rect (x1, y1, x2, y2) of the monitoring area 7 obtained in this way reflect the sliding amount (position) and reclining amount (shape) of the seat 8.

That is, as shown in FIG. 6, if the state of the seat 8 is the standard state (the seat 8 is located furthest forward within the slidable range and the rotation angle φr=0 degree), the area setting unit 432 The monitoring area 7 is set at a predetermined position (rect(dx1, dy1, dx2, dy2)+(sx, sy)). Furthermore, as shown in FIG. 7, if the state of the seat 8 is not the reference state, the region setting unit 432 shifts the monitoring region 7 from the default position according to the state of the seat 8. In other words, the area setting unit 432 moves the monitoring area 7 in parallel along the length axis Y according to the first sensor value Vs and the second sensor value Vr.

The signal processing device 4 described above changes the monitoring area 7 without moving the radio wave sensor 2, and eliminates the need for a configuration for moving the radio wave sensor 2. Therefore, the signal processing device 4 can change the monitoring area 7 according to the state of the seat 8 with a simple configuration. Furthermore, the signal processing device 4 can change the monitoring area 7 according to the state of the seat 8 using a simple algorithm.

Note that the area setting unit 432 may change the vertical position of the monitoring area 7 according to the reclining amount (shape) of the seat 8. Further, the area setting unit 432 may set the monitoring area 7 so as to intersect the XY plane. Further, the area setting unit 432 may change the inclination of the monitoring area 7 intersecting the XY plane according to the reclining amount (shape) of the seat 8.

(4.3) Determination Unit The determination unit 431 uses a part of the reflected waves reflected in the monitoring area 7 set by the area setting unit 432, out of the total reflected waves in the vehicle interior 91, to A determination process is performed to determine the condition of the person. Therefore, the determination unit 431 performs the following processing in order to extract a signal component due to some of the reflected waves reflected at the monitoring area 7 from the radio wave sensor signal J1.

(4.3.1) Spatial Correlation Matrix Hereinafter, the derivation process of the spatial correlation matrix will be explained using FIG. 8.

The determination unit 431 periodically generates a frequency domain radio wave sensor signal Ja(N) by performing fast Fourier transform (FFT) on the time domain radio wave sensor signal J1. N is a natural number 1, 2, 3, . . . , n, . . . representing a sample number (corresponding to time) of the radio wave sensor signal Ja (N). The radio wave sensor signal J1 in the time domain includes information on each beat signal of channels CH1 to CH4 (see FIG. 3), and the radio wave sensor signal Ja (N) in the frequency domain contains information on each beat signal of channels CH1 to CH4. is a complex signal in the frequency domain containing

Since the frequency of the radio sensor signal J1 has a correlation with the distance D to the object, the determination unit 431 can extract information about the distance D to the object from the radio sensor signal Ja(N) in the frequency domain. Therefore, the determination unit 431 divides the detectable range of the distance D into a plurality of distance ranges (corresponding to frequency bins), and determines a spatial correlation matrix R^ in the distance range DR1 corresponding to the distance to the monitoring region 7. Specifically, the determination unit 431 generates vectors g^(1) to g^(n) from the radio wave sensor signal Ja(N) in the frequency domain. Vectors g^(1) to g^(n) are information on reflected waves in distance range DR1, and are composed of components of channels CH1 to CH4. Note that the symbol "^" represents a vector or a matrix.

The determination unit 431 uses Equation 4 to determine the spatial correlation matrix R^ of the vectors g^(1) to g^(n). If the number of channels (the number of virtual antennas) is M, the spatial correlation matrix R^ becomes a square matrix with M rows and M columns. Note that in Equation 4, the superscript H represents conjugate transposition.

(4.3.2) Arrival Direction Estimation The radio wave sensor 2 is a MIMO type radio wave sensor, and as shown in FIG. 9, has four virtual antennas 2a to 2d arranged at equal intervals. The virtual antennas 2a to 2d are linearly arranged in the order of 2a, 2b, 2c, and 2d. That is, the four virtual antennas 2a to 2d constitute a linear array antenna having four channels CH1 to CH4. In this case, by setting the installation interval d1 of the virtual antennas 2a to 2d to 1/2 of the wavelength λ (reciprocal of the transmission frequency) of the transmitted wave, the detectable range can be widened and the angular resolution can be improved. Can be done.

Since the radio wave sensor 2 is a MIMO type radio wave sensor, the determination unit 431 can estimate the direction of arrival (angle of arrival) θ of the reflected wave. For the arrival direction θ, the normal direction of the line segment 200 connecting the virtual antennas 2a to 2d is set to 0 degrees. The direction of arrival θ is greater than 0 degrees in a direction that obliquely intersects the line segment 200 from one end side of the line segment 200. The arrival direction θ is set to be smaller than 0 degrees in a direction diagonally intersecting the line segment 200 from the other end side of the line segment 200. In this case, the phase difference Φc between the signals of channels CH1 to CH4, which is determined according to the direction of arrival θ, is defined as shown in Equation 5.

The determination unit 431 generates a weighted signal Jb(N) by performing a weighted average of the vectors g^(1) to g^(n) using the weighting coefficient w _m for each channel using Equation 6. . From Equation 6, it can be seen that the weighting signal Jb(N) is obtained from the weighting coefficient vector w^, each element of which is the weighting coefficient _wm for each channel, and the vector g^(N). Note that in Equation 6, w _m is a weighting coefficient for each channel, g _m (N) is a component of each channel in vector g^(N), and superscript * represents a complex conjugate. Further, m is a channel number, and M is the number of channels (the number of virtual antennas), and in this embodiment, M=4.

The power Po(w^) of the weighting signal Jb(N) is determined by Equation 7. From Equation 7, it can be seen that the power Po(w^) is obtained from the spatial correlation matrix R^ and the weighting coefficient vector w^ (vector having each of the weighting coefficients _wm of each channel as elements).

Therefore, the determination unit 431 sets each weighting coefficient _wm of the weighting coefficient vector w^ as a weighting coefficient that depends on the direction of arrival θ, and sets the power Po(w^) of the weighted signal Jb(N) as the likelihood of the direction of arrival θ. By using this, the direction of arrival θ of the reflected wave is estimated. The simplest weighting coefficient vector w^ is defined by the steering vector a^(θ) of the beamforming method, as shown in Equation 8. Note that from Equation 5, the direction of arrival θ can be expressed using the phase difference Φc.

In this embodiment, the Capan method is used to improve the directivity of the linear array antenna with respect to the direction of arrival θ. The Capan method uses a weighting coefficient vector w^ that minimizes the power Po(w^) as shown in Equation 9.

In the Capan method, by solving Equation 9 according to the constraint conditions of Equation 10, a weighting coefficient vector w _cap ^ shown in Equation 11 is obtained.

Then, by substituting the weighting coefficient vector w _cap ^ shown in equation 11 to w ^ in equation 7, the power Po _cap (θ) shown in equation 12 is obtained. The determination unit 431 can estimate the direction of arrival θ of the reflected wave by using the power Po _cap (θ) as the likelihood of the direction of arrival θ.

(4.3.3) Determination Process By estimating the direction of arrival θ as described above, the determination unit 431 estimates the direction of arrival θ based on a portion of the reflected waves reflected at the monitoring area 7 among the total reflected waves within the vehicle interior 91. Then, the determination process can be performed. Specifically, the determination unit 431 performs determination processing based on the distance D corresponding to the monitoring area 7 and the power Po _cap (θ) of the reflected wave in the direction of arrival θ.

For example, the area setting unit 432 sets the six seats 8 (front seats 81, 82, second row seats 83, 84, third row seats 85, 86) in the vehicle interior 91 as shown in FIG. Six monitoring areas 7 (71 to 76) are set respectively. The monitoring areas 71 to 76 fall within a semicircular irradiation range B1 of the transmitted wave. The determining unit 431 can determine the state of the person in each of the six monitoring areas 71-76 based on some of the reflected waves reflected at each of the six monitoring areas 71-76.

In the present embodiment, the determination unit 431 determines whether or not there is a person in the monitoring area 7 as the state of the person in the monitoring area 7 . That is, the determination unit 431 determines whether a person is sitting in each of the six seats 8 in the vehicle interior 91.

Specifically, the determination unit 431 uses the power Po _cap (θ) as the likelihood, and if the likelihood in the monitoring region 7 is equal to or higher than a predetermined likelihood threshold K1, as in the characteristic L1 of FIG. 11, A differential operation is performed on the characteristic L1. The determination unit 431 compares the average value (differential average value) of a plurality of differential values of the characteristic L1 obtained in a predetermined period with a determination threshold value, and if the differential average value is equal to or greater than a predetermined determination threshold value, the monitoring area is determined. It is determined that a person is sitting in seat 8 corresponding to seat 7. If the differential average value is less than the determination threshold, the determination unit 431 determines that no person is sitting in the seat 8 corresponding to the monitoring area 7 . That is, the determination unit 431 determines that a person is sitting on the seat 8 when the time variation (fluctuation) of the likelihood is large, and determines that there is no person sitting on the seat 8 when the time variation of the likelihood is small. do.

Further, if the likelihood in the monitoring area 7 is less than the likelihood threshold K1, as in the characteristic L2 in FIG. .

Each of the monitoring areas 7 is set based on the position and shape of each seat 8, so the determination unit 431 determines whether or not a person is sitting in each of the six seats 8 in the vehicle interior 91. Based on the position and shape of 8, the determination can be made with high accuracy.

The longitudinal position (sliding amount) of the seat 8 and the rotation angle (reclining amount) of the backrest 8b are changed at any time depending on the physique of the person, the number of passengers, etc. However, in this embodiment, the monitoring area 7 is set to overlap the person seated on the seat 8, regardless of the amount of slide of the seat 8 and the amount of recline of the backrest 8b. As a result, even if the sliding amount of the seat 8 and the reclining amount of the backrest 8b change, the determination unit 431 can accurately determine whether or not a person is sitting on the seat 8.

It is preferable that the determination unit 431 temporarily stop the determination process when at least one of the slide motor and reclining motor of the seat 8 operates. That is, it is preferable that the determination unit 431 temporarily stop the determination process when the state of the seat 8 changes. In this case, upon detecting a change in the state of the seat 8, the determination unit 431 stops the determination process. When the state of the seat 8 becomes constant for a predetermined period of time, the area setting unit 432 resets the monitoring area 7 based on the changed state of the seat 8, and then the determining unit 431 restarts the determination process. do. Therefore, the determination unit 431 can suppress erroneous determination by stopping the determination process while the state of the seat 8 is changing.

Preferably, the determination unit 431 determines that no person is sitting on the seat 8 if the shape of the seat 8 is a shape that makes it impossible for a person to sit (a shape that does not allow a person to sit). Specifically, the determination unit 431 determines that the shape of the seat 8 is a shape that does not allow seating if the backrest 8b is tilted backward and the rotation angle φr becomes larger than a predetermined first value. Further, the determining unit 431 determines that even if the backrest 8b is tilted forward and the rotation angle φr becomes smaller than a predetermined second value (a value smaller than the first value), the shape of the seat 8 is determined to be a shape that does not allow seating. I judge that there is. Therefore, the determining unit 431 can suppress erroneous determinations by determining that no person is sitting on the seat 8 if the shape of the seat 8 is in a state where seating is not possible.

(4.4) Communication Unit The communication unit 433 transmits the determination result of the determination unit 431 to the data analysis device 5 as a determination signal J3. The data analysis device 5 can receive the determination signal J3. The data analysis device 5 issues a notification, alert, or warning to the occupants of the vehicle 9 based on the determination signal J3. The data analysis device 5 includes, for example, an ECU (Electronic Control Unit) of the vehicle 9.

For example, the data analysis device 5 receives a monitoring signal representing the state of each seatbelt of the vehicle 9 via an in-vehicle network such as a CAN (Controller Area Network). The data analysis device 5 determines, based on the determination signal J3 and the seat belt monitoring signal, whether or not the seat belt of the seat 8 where the presence of a person is detected while the vehicle 9 is running is in the unlocked state. judge. If the seatbelt of the seat 8 where the presence of a person is detected while the vehicle 9 is running is in the unlocked state, the data analysis device 5 causes a notification unit (not shown) to perform a notification operation. When executing the notification operation, the notification unit uses, for example, an audio device or a navigation device provided in the vehicle interior 91 to output a notification sound (buzzer sound, message, etc.) from a speaker provided in the vehicle interior 91. ) is output. The notification sound is, for example, a buzzer sound or a message such as "Please fasten your seat belt."

Therefore, when there is a person in the vehicle compartment 91 who is not wearing a seatbelt, the sensor system 1 can reduce the occurrence of the seatbelt not being worn by prompting the person to wear the seatbelt through a notification operation.

(Modified example)
The determination unit 431 is not limited to a configuration that uses FFT, and for example, performs a discrete cosine transform (DCT) on the time domain radio wave sensor signal J1 to obtain the frequency domain radio wave sensor signal Ja (N). may be generated.

The determination unit 431 may determine the state of biological information such as the person's heartbeat, pulse, or blood flow as the person's condition. In this case, the data analysis device 5 can analyze the alertness level of the person (particularly the driver) or determine whether the person is falling asleep.

Further, the sensor system 1 may be installed in a moving object other than the vehicle 9, such as an airplane or a ship. In this case, the monitoring area 7 is set corresponding to a seat where a crew member of an airplane, a ship, or the like sits.

Moreover, the sensor system 1 may be installed in an indoor space. The indoor space may be an office, a factory, a school classroom, a hospital room in a medical facility, or a room in a facility for the elderly. In this case, the radio wave sensor 2 receives reflected waves in the indoor space, and the determination unit 431 determines the state of the person in the monitoring area 7 of the indoor space. The monitoring area 7 is set corresponding to the seats where people sit in the indoor space. That is, the sensor system 1 can perform presence management or health management in an indoor space.

Further, the seat 8 may have a configuration in which the lift or vertical of the seat surface 8a can be adjusted. That is, the state of the seat 8 may include the position of the seat surface 8a in the height direction or the angle of the seat surface 8a. The position of the seat surface 8a in the height direction corresponds to the position of the seat 8, and the angle of the seat surface 8a corresponds to the shape of the seat 8.

(summary)
As described above, the signal processing device (4) of the first aspect according to the embodiment includes a first acquisition section (41), a second acquisition section (42), a determination section (431), and a region setting section. (432). The first acquisition unit (41) receives a radio wave sensor signal (J1) output from a radio wave sensor (2) that receives reflected waves of electromagnetic waves radiated into a predetermined space. The second acquisition unit (42) receives seat sensor signals (J21, J22) output from the seat sensor (3) that detects the state of the seat (8) in a predetermined space. The determination unit (431) performs determination processing to determine the state of a person within a predetermined space based on the radio wave sensor signal (J1). The area setting unit (432) sets a monitoring area (7) in which the determination process is performed in a predetermined space based on the seat sensor signals (J21, J22). The determination unit (431) performs determination processing using a portion of the reflected waves reflected at the monitoring area (7).

Since the signal processing device (4) described above does not require a configuration for moving the radio wave sensor (2), the monitoring area (7) can be changed according to the state of the seat (8) with a simple configuration.

Further, in the signal processing device (4) of the second aspect according to the embodiment, in the first aspect, the determination unit (431) determines whether or not a person is sitting in the seat (8) as the condition of the person. It is preferable to judge.

The signal processing device (4) described above can accurately determine whether a person is sitting on the seat (8) even if the state of the seat (8) changes.

Further, in the signal processing device (4) of the third aspect according to the embodiment, in the first or second aspect, the determination unit (431) temporarily executes the determination process when the state of the seat (8) changes. It is preferable to stop at.

The signal processing device (4) described above can suppress erroneous determinations.

Further, in the signal processing device (4) of the fourth aspect according to the embodiment, in any one of the first to third aspects, the area setting unit (432) determines that the state of the seat (8) is the reference state. If so, it is preferable to set the monitoring area (7) at a predetermined position. The area setting unit (432) shifts the monitoring area (7) from the default position according to the state of the seat (8) if the state of the seat (8) is not the reference state.

The signal processing device (4) described above can change the monitoring area (7) according to the state of the seat (8) using a simple algorithm.

Further, in the signal processing device (4) of the fifth aspect according to the embodiment, in any one of the first to fourth aspects, the state of the seat (8) is determined by the shape of the seat (8) and the seat ( It is preferable that at least one of the positions of 8) is included.

The signal processing device (4) described above has a simple configuration and can change the monitoring area (7) depending on at least one of the shape and position of the seat (8).

Moreover, in the signal processing device (4) of the sixth aspect according to the embodiment, in the fifth aspect, it is preferable that the state of the seat (8) includes the shape of the seat (8). The determination unit (431) determines that no person is sitting on the seat (8) if the shape of the seat (8) makes it impossible for a person to sit there.

The signal processing device (4) described above can suppress erroneous determinations.

Further, in the signal processing device (4) of the seventh aspect according to the embodiment, in the fifth or sixth aspect, the position of the seat (8) includes the position of the seat (8) in the longitudinal direction; The shape of 8) preferably includes the inclination of the backrest (8b) of the seat (8).

The signal processing device (4) described above has a simple configuration and can change the monitoring area (7) according to at least one of the longitudinal position of the seat (8) and the inclination of the backrest (8b).

Further, the sensor system (1) of the eighth aspect according to the embodiment includes the signal processing device (4) of any one of the first to seventh aspects and a radio wave sensor (2).

The sensor system (1) described above has a simple configuration and can change the monitoring area (7) depending on the state of the seat (8).

Moreover, it is preferable that the sensor system (1) of the ninth aspect according to the embodiment further includes a seat sensor (3) in the eighth aspect.

The sensor system (1) described above can easily detect the condition of the seat (8).

Further, in the sensor system (1) of the tenth aspect according to the embodiment, in the eighth or ninth aspect, the predetermined space is the cabin (91) of the vehicle (9), and the radio wave sensor (2) is , it is preferable to receive reflected waves from the vehicle interior (91).

The above-described sensor system (1) can accurately determine the condition of the person inside the vehicle interior (91).

Further, in the sensor system (1) of the eleventh aspect according to the embodiment, in the eighth or ninth aspect, the predetermined space is an indoor space, and the radio wave sensor (2) receives reflected waves in the indoor space. It is preferable to do so.

The sensor system (1) described above can accurately determine the state of a person in an indoor space.

1 Sensor system 2 Radio wave sensor 3 Seat sensor 4 Signal processing device 41 First acquisition section 42 Second acquisition section 431 Judgment section 432 Area setting section 7 Monitoring area 8 Seat 8b Backrest 9 Vehicle 91 Vehicle interior J1 Radio wave sensor signal J21 First seat Sensor signal (seat sensor signal)
J22 2nd seat sensor signal (seat sensor signal)

Claims (11)

a first acquisition unit that receives a radio wave sensor signal output from a radio wave sensor that receives reflected waves of electromagnetic waves radiated into a predetermined space;
a second acquisition unit that receives a seat sensor signal output from a seat sensor that detects the state of the seat in the predetermined space;
a determination unit that performs determination processing to determine the state of a person in the predetermined space based on the radio wave sensor signal;
an area setting unit that sets a monitoring area in which the determination process is performed for the predetermined space based on the seat sensor signal;
The determination unit performs the determination process using a portion of the reflected waves reflected at the monitoring area. The signal processing device according to claim 1, wherein the determination unit determines whether or not the person is sitting in the seat as the state of the person. The signal processing device according to claim 1 or 2, wherein the determination unit temporarily stops the determination process when the state of the seat changes. The area setting section includes:
If the state of the seat is a reference state, setting the monitoring area to a predetermined position;
The signal processing device according to any one of claims 1 to 3, wherein if the state of the seat is not the reference state, the monitoring area is shifted from the predetermined position depending on the state of the seat. The signal processing device according to any one of claims 1 to 4, wherein the state of the seat includes at least one of a shape of the seat and a position of the seat. The state of the seat includes the shape of the seat,
The signal processing device according to claim 5, wherein the determination unit determines that the person is not sitting on the seat if the shape of the seat is such that it is impossible for the person to sit on the seat. The position of the seat includes the position of the seat in the front and back direction,
The signal processing device according to claim 5 or 6, wherein the shape of the seat includes an inclination of a backrest of the seat. A signal processing device according to any one of claims 1 to 7,
A sensor system comprising: the radio wave sensor. The sensor system according to claim 8, further comprising the seat sensor. The predetermined space is a cabin of a vehicle,
The sensor system according to claim 8 or 9, wherein the radio wave sensor receives the reflected wave from the vehicle interior. The predetermined space is an indoor space,
The sensor system according to claim 8 or 9, wherein the radio wave sensor receives the reflected wave in the indoor space.

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