Antenna device, signal processing device, radar system, and information processing device

Abstract

The present invention achieves a radar system capable of performing three-dimensional imaging in real-time. An array antenna (12) comprises: a first antenna group (121) comprising M patch antennas (121Rx·Tx) arranged in one or two rows along a first straight line (L1); and a second antenna group (122) comprising N patch antennas (122Rx·Tx) arranged in one or two rows along a second straight line (L2) orthogonal to the first straight line (L1). The angle formed by the longitudinal axis of each patch antenna belonging to the first antenna group (121) and the first straight line (L1) is a common angle greater than 0° and less than 180°, and the angle formed by the longitudinal axis of each patch antenna belonging to the second antenna group (122) and the second straight line (L2) is a common angle greater than 90° and less than 270°.

Description

Antenna device, signal processing device, radar system, and information processing device

[0001] The present invention relates to an antenna device equipped with an array antenna. The present invention also relates to a signal processing device that processes IF signals acquired from the antenna device. The present invention also relates to an information processing device that processes three-dimensional images acquired from the signal processing device. The present invention also relates to a radar system including an antenna device equipped with an array antenna and a signal processing device that processes IF signals acquired from the antenna device.

[0002] The demand for monitoring systems is increasing due to factors such as the rising number of elderly households and the shortage of medical professionals. These monitoring systems have the function of detecting abnormalities in the monitored person and issuing an alarm. One method for detecting abnormalities is imaging using a camera. However, imaging with a camera has the problem of reduced detection capabilities in low-light conditions such as at night. Furthermore, from the perspective of protecting the privacy of the monitored person, imaging with a camera may not be desirable in some cases.

[0003] One possible solution to these problems is to use a radar system (e.g., a millimeter-wave radar imaging system) instead of a camera. Radar systems do not acquire color information, nor do they acquire shape information in as much detail as cameras. Therefore, it is possible to acquire the information necessary for monitoring while protecting the privacy of the person being monitored. Examples of documents disclosing such radar systems include Patent Documents 1 and 2.

[0004] Japanese Patent Publication No. 2007-333656 Japanese Special Publication No. 2021-527832

[0005] However, the radar system described in Patent Document 1 is a radar system for performing two-dimensional imaging. Therefore, it has the problem of not being able to acquire information necessary for monitoring, such as the posture of the person being monitored. Furthermore, the radar system described in Patent Document 2 is a synthetic aperture radar system that performs scanning while moving the antenna. Therefore, it is not possible to perform three-dimensional imaging in real time.

[0006] One aspect of the present invention has been made in view of the above-mentioned problems, and one of its objectives is to realize a radar system capable of real-time three-dimensional imaging. Another objective of the present invention is to provide an antenna device and a signal processing device that contribute to the realization of such a radar system.

[0007] An antenna device according to one aspect of the present invention comprises a substrate and an array antenna consisting of a plurality of patch antennas formed on one main surface of the substrate, wherein the array antenna is composed of a first antenna group consisting of M patch antennas (where M is any natural number of 3 or more) arranged in one or two rows along a first straight line, and a second antenna group consisting of N patch antennas (where N is any natural number of 3 or more) arranged in one or two rows along a second straight line perpendicular to the first straight line, wherein the angle between the longitudinal axis of each patch antenna belonging to the first antenna group and the first straight line is a common angle greater than 0° and less than 180°, and the angle between the longitudinal axis of each patch antenna belonging to the second antenna group and the second straight line is a common angle greater than 90° and less than 270°.

[0008] A signal processing device according to one aspect of the present invention is characterized by comprising: a memory storing the value of V(R, θ, φ) defined by the following formula (a) for each calculation grid (R, θ, φ); and a processor that calculates the cross-correlation P(R, θ, φ) according to the following formula (b) by referring to the value of V(R, θ, φ) stored in the memory and the IF signal acquired from the antenna device.

[0009]

[0010] Here, A(R, θ, φ) represents the eye response corresponding to the computation grid (R, θ, φ), and s ＾ (R, θ, φ, f Ｒ(R, θ, φ)) is the signal waveform of the IF signal pre-calculated using the FMCW (Frequency Modulated Continuous Wave) signal model, and is the beat frequency f derived from the reflected wave from the target existing in the calculation grid (R, θ, φ). Ｒ It represents the signal waveform of the IF signal with (R, θ, φ) (s ＾ In the formula, there is a ^ above s).

[0011]

[0012] Here, X ＾ [f Ｒ ～ (R, θ, φ)] is the IF signal acquired from the antenna device, and is the beat frequency f derived from the reflected wave from the target existing in the calculation grid (R, θ, φ). Ｒ ～ It represents the result of performing Range-FFT (Range Fast Fourier Transform) on the IF signal with (R, θ, φ) (X ＾ In the formula, there is a ^ above X, f Ｒ ～ In the formula, f Ｒ above ~), V － (R, θ, φ) Ｈ represents the Hermitian transpose of the value of V(R, θ, φ) stored in the memory (V － In the formula, there is a - above V).

[0013] According to one aspect of the present invention, a radar system capable of performing three-dimensional imaging in real time can be realized.

[0014] It is a plan view showing the configuration of an antenna device according to an embodiment of the present invention. It is a block diagram showing the configurations of a signal processing device and an information processing device according to an embodiment of the present invention. It is a diagram showing an example of a target model used by the information processing device shown in FIG. 2. It is a diagram showing an example of a three-dimensional image generated by the information processing device shown in FIG. 2.

[0015] (Configuration of Antenna Device) The antenna device 1 according to an embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a plan view showing the configuration of the antenna device 1.

[0016] The antenna device 1 comprises a substrate 11, an array antenna 12, and integrated circuits 131 and 132. The array antenna 12 is formed on the first main surface (front surface) of the substrate 11. The integrated circuits 131 and 132 are mounted on the first main surface of the substrate 11. The second main surface (back surface) of the substrate 11 is covered with a conductive layer (not shown) that functions as a ground.

[0017] The array antenna 12 is composed of a first antenna group 121 and a second antenna group 122. The first antenna group 121 consists of M patch antennas 121Rx, 121Tx arranged in one or two rows along a first straight line L1. Here, M is any natural number greater than or equal to 3. In this embodiment, M = 14. The second antenna group 122 consists of N patch antennas 122Rx, 122Tx arranged in one or two rows along a second straight line L2 that is perpendicular to the first straight line L1. Here, N is any natural number greater than or equal to 3. In this embodiment, N = 14.

[0018] Each patch antenna 121Rx, 121Tx, 122Rx, and 122Tx is composed of multiple patches 12b (in this embodiment, three rectangular patches) arranged on the feed line 12a. In the following description, the longitudinal axis of the patch antennas 121Rx, 121Tx, 122Rx, and 122Tx refers to the central axis of the feed line 121a.

[0019] The orientation of each patch antenna 121Rx, 121Tx belonging to the first antenna group 121 is determined such that the longitudinal axis of the patch antennas 121Rx, 121Tx intersects the first straight line L1 at an angle. That is, the angle θ1 formed by the longitudinal axis of the patch antennas 121Rx, 121Tx and the first straight line L1 is determined to be 0° < θ1 < 180°. Here, the angle θ1 is measured counterclockwise from the first straight line L1 toward the longitudinal axis of the patch antennas 121Rx, 121Tx. In this embodiment, θ1 = 45°.

[0020] In this embodiment, the patch antennas 121Rx and 121Tx belonging to the first antenna group 121 are arranged in two rows. That is, among the patch antennas 121Rx and 121Tx belonging to the first antenna group 121, M Ｒｘ The receiving patch antennas 121Rx are arranged in a line on the first straight line L1. Here, M Ｒｘ is any natural number between 2 and M-1. In this embodiment, M Ｒｘ = 8. On the other hand, among the patch antennas 121Rx and 121Tx belonging to the first antenna group 121, M Ｔｘ = M - M Ｒｘ The individual transmitting patch antennas 121Tx are arranged in a line on another straight line L1' parallel to the first straight line L1. In this embodiment, M Ｔｘ = 6.

[0021] The patch antennas 121Rx and 121Tx belonging to the first antenna group 121 may be arranged in a line on the first straight line L1. In this case, the order in which the receiving patch antenna 121Rx and the transmitting patch antenna 121Tx are arranged is not particularly limited and can be set as appropriate.

[0022] The orientation of each patch antenna 122Rx, 122Tx belonging to the second antenna group 122 is determined such that the longitudinal axis of the patch antennas 122Rx, 122Tx intersects the second straight line L2 at an angle. That is, the angle θ2 formed by the longitudinal axis of the patch antennas 122Rx, 122Tx and the second straight line L2 is determined to be 90° < θ2 < 270°. Here, the angle θ2 is measured counterclockwise from the second straight line L2 toward the longitudinal axis of the patch antennas 122Rx, 122Tx. In this embodiment, the longitudinal axis of each patch antenna 122Rx, 122Tx belonging to the second antenna group 122 is parallel to the longitudinal axis of each patch antenna 121Rx, 121Tx belonging to the first antenna group 121. In this embodiment, θ2 = 135°.

[0023] Furthermore, in this embodiment, the patch antennas 122Rx and 122Tx belonging to the second antenna group 122 are arranged in two rows. Of the patch antennas 122Rx and 122Tx belonging to the second antenna group 122, N Ｒｘ The receiving patch antennas 122Rx are arranged in a line on the second straight line L2. Here, N Ｒｘ is any natural number between 2 and N-1. In this embodiment, N Ｒｘ = 8. On the other hand, among the patch antennas 122Rx and 122Tx belonging to the second antenna group 122, N Ｔｘ = N - N Ｒｘ The individual transmitting patch antennas 122Tx are arranged in a line on another straight line L2' parallel to the second straight line L2. In this embodiment, N Ｔｘ = 6.

[0024] The patch antennas 122Rx and 122Tx belonging to the second antenna group 122 may be arranged in a line on the second straight line L2. In this case, the order in which the receiving patch antenna 122Rx and the transmitting patch antenna 122Tx are arranged is not particularly limited and can be set as appropriate.

[0025] The receiving patch antenna 121Rx belonging to the first antenna group 121 is positioned on one of the two half-lines obtained by bisecting the first straight line L1 at the intersection point P with the second straight line L2. Similarly, the receiving patch antenna 122Rx belonging to the second antenna group 122 is positioned on one of the two half-lines obtained by bisecting the straight line L2 at the intersection point P with the straight line L1. In other words, the receiving patch antennas 121Rx and 122Rx constituting the array antenna 12 are arranged in an L-shape.

[0026] Furthermore, the transmitting patch antenna 121Tx belonging to the first antenna group 121 is positioned on one of the two half-lines obtained by bisecting the straight line L1' at the intersection point P' with the straight line L2'. Similarly, the transmitting patch antenna 122Tx belonging to the second antenna group 122 is positioned on one of the two half-lines obtained by bisecting the straight line L2' at the intersection point P' with the straight line L1'. In other words, the transmitting patch antennas 121Tx and 122Tx that constitute the array antenna 12 are arranged in an L-shape.

[0027] Integrated circuits 131 and 132 are mounted on the main surface of the substrate 11 (the main surface on which the array antenna 12 is formed).

[0028] The integrated circuit 131 includes, for example, a transmitting circuit that generates a transmit signal (e.g., an FMCW signal) and supplies it to each of the transmitting patch antennas 121Tx, and a receiving circuit that acquires a received signal from each of the receiving patch antennas 121Rx, and generates an IF signal representing the frequency component of the difference between the transmit signal and the received signal, and supplies it to the signal processing device 2, which will be described later.

[0029] The integrated circuit 131 is connected to each of the four receiving patch antennas 121Rx and each of the three transmitting patch antennas 121Tx included in the first antenna group 121. The four feed lines 141Rx connecting the integrated circuit 131 to each of the receiving patch antennas 121Rx are of equal length. Similarly, the three feed lines 141Tx connecting the integrated circuit 131 to each of the transmitting patch antennas 121Tx are of equal length. Note that the receiving feed lines 141Rx and the transmitting feed lines 141Tx may or may not be of equal length.

[0030] The integrated circuit 132 includes, for example, a transmitting circuit that generates a transmit signal (e.g., an FMCW signal) and supplies it to each of the transmitting patch antennas 122Tx, and a receiving circuit that acquires a received signal from each of the receiving patch antennas 122Rx, and generates an IF signal representing the frequency component of the difference between the transmit signal and the received signal, and supplies it to the signal processing device 2, which will be described later.

[0031] The integrated circuit 132 is connected to each of the four receiving patch antennas 122Rx and each of the three transmitting patch antennas 122Tx included in the second antenna group 122. The four feed lines 142Rx connecting the integrated circuit 132 to each of the receiving patch antennas 122Rx are of equal length. Similarly, the three feed lines 142Tx connecting the integrated circuit 132 to each of the transmitting patch antennas 122Tx are of equal length. Note that the receiving feed lines 142Rx and the transmitting feed lines 142Tx may or may not be of equal length.

[0032] (Features of the antenna device) The antenna device 1 is implemented as a printed circuit board on which an array antenna 12 is printed on a substrate 11.

[0033] Therefore, the antenna device 1 is easy to manufacture and requires no or easy calibration after shipment. The reason it is easy to manufacture is that the array antenna 12 can be easily formed using known circuit printing techniques such as the additive method or the subtractive method. Furthermore, the reason that no or easy calibration is required after shipment is that the patch antennas 121Rx, 121Tx, 122Rx, and 122Tx that constitute the array antenna 12 are formed on a single substrate 11, so their relative positions do not change after shipment.

[0034] Furthermore, in the antenna device 1, the array antenna 12 is composed of a first antenna group 121 consisting of M patch antennas 121Rx, 121Tx arranged in one or two rows along a first straight line L1, and a second antenna group 122 consisting of N patch antennas 122Rx, 122Tx arranged in one or two rows along a second straight line L2 that is perpendicular to the first straight line L1.

[0035] Therefore, by using an antenna device 1 as a radar front end, in which the first straight line L1 coincides with the azimuth direction and the second straight line L2 coincides with the elevation direction, a two-dimensional distance image with extent in both the azimuth and elevation directions can be obtained. Furthermore, a two-dimensional distance image can also be considered a three-dimensional image with three dimensions: azimuth, elevation, and distance.

[0036] Furthermore, in the antenna device 1, the angle θ1 formed between the longitudinal axis of each patch antenna 121Rx, 121Tx belonging to the first antenna group 121 and the first straight line L1 is a common angle that is greater than 0° and less than 180°. Also, the angle θ2 formed between the longitudinal axis of each patch antenna 122Rx, 122Tx belonging to the second antenna group 122 and the second straight line L2 is a common angle that is greater than 90° and less than 270°.

[0037] This allows the spacing between two adjacent patch antennas 121Rx and 121Tx belonging to the first antenna group 121 in the same row to be smaller than the length of the patch antennas 121Rx and 121Tx (physical size in the longitudinal axis direction). Similarly, the spacing between two adjacent patch antennas 122Rx and 122Tx belonging to the second antenna group 122 in the same row can be smaller than the length of the patch antennas 122Rx and 122Tx. Therefore, the degree of freedom in designing the array antenna 12 can be greatly increased.

[0038] Furthermore, the angle θ1 formed between the longitudinal axis of each patch antenna 121Rx, 121Tx and the first straight line L1 is preferably between 20° and 160°. Also, the angle θ2 formed between the longitudinal axis of each patch antenna 122Rx, 122Tx and the second straight line L2 is preferably between 110° and 250°.

[0039] This allows for further reduction in the spacing between two adjacent patch antennas 121Rx, 121Tx belonging to the first antenna group 121 within the same row. Similarly, it allows for further reduction in the spacing between two adjacent patch antennas 122Rx, 122Tx belonging to the second antenna group 122 within the same row. Therefore, the design flexibility of the array antenna 12 can be further increased.

[0040] Furthermore, in the antenna device 1, the first antenna group 121 is arranged on the first straight line L1. ＲｘA receiving patch antenna 121Rx and M positioned on another straight line L1' parallel to the first straight line L1. Ｔｘ = M - M Ｒｘ It consists of a second antenna group 122 arranged on the second straight line L2. Ｒｘ The receiving patch antenna 122Rx and N are positioned on another straight line L2' parallel to the second straight line L2. Ｔｘ = N - N Ｒｘ It consists of several transmitting patch antennas 122Tx.

[0041] As a result, compared to the case where the receiving patch antenna 121Rx and the transmitting patch antenna 121Tx constituting the first antenna group 121 are arranged on the first straight line L1, crosstalk caused by the reception of a signal transmitted from the transmitting patch antenna 121Tx by an adjacent receiving patch antenna 121Rx can be reduced. Furthermore, compared to the case where the receiving patch antenna 122Rx and the transmitting patch antenna 122Tx constituting the second antenna group 122 are arranged on the second straight line L2, crosstalk caused by the reception of a signal transmitted from the transmitting patch antenna 122Tx by an adjacent receiving patch antenna 122Rx can be reduced.

[0042] Furthermore, it is preferable that the receiving patch antenna 121Rx belonging to the first antenna group 121 is positioned on one of the two half-lines obtained by bisecting the straight line L1 at the intersection point P with the straight line L2. Similarly, it is preferable that the receiving patch antenna 122Rx belonging to the second antenna group 122 is positioned on one of the two half-lines obtained by bisecting the straight line L2 at the intersection point P with the straight line L1. In other words, it is preferable that the receiving patch antennas 121Rx and 122Rx constituting the array antenna 12 are arranged in an L-shape.

[0043] This allows the array antenna 12 to function as a receiving antenna with a large aperture length in both the direction parallel to the first straight line L1 and the direction parallel to the second straight line L2, without unnecessarily increasing the number of patch antennas 121Rx and 122Rx or unnecessarily complicating the power supply paths to the patch antennas 121Rx and 122Rx. Therefore, when an antenna device 1 arranged so that the first straight line L1 coincides with the azimuth direction and the second straight line L2 coincides with the elevation direction is used as a radar front end, a radar system with high resolution in both the azimuth and elevation directions can be realized.

[0044] Furthermore, the transmitting patch antenna 121Tx belonging to the first antenna group 121 is positioned on one of the two half-lines obtained by bisecting the straight line L1' at the intersection point P' with the straight line L2'. Similarly, the transmitting patch antenna 122Tx belonging to the second antenna group 122 is positioned on one of the two half-lines obtained by bisecting the straight line L2' at the intersection point P' with the straight line L1'. In other words, the transmitting patch antennas 121Tx and 122Tx that constitute the array antenna 12 are arranged in an L-shape.

[0045] This allows the array antenna 12 to function as a transmitting antenna with a large aperture length in both the direction parallel to the first straight line L1 and the direction parallel to the second straight line L2, without unnecessarily increasing the number of patch antennas 121Tx and 122Tx or unnecessarily complicating the feed paths to the patch antennas 121Tx and 122Tx. Therefore, when an antenna device 1 arranged so that the first straight line L1 coincides with the azimuth direction and the second straight line L2 coincides with the elevation direction is used as a radar front end, a radar system with high resolution in both the azimuth and elevation directions can be realized.

[0046] Furthermore, in the antenna device 1, M belonging to the first antenna group 121 Ｒｘ Of the receiving patch antennas 121Rx, for two or more patch antennas 121Rx connected to the same integrated circuit 131, the feed lines 141Rx connecting the integrated circuit 131 and each patch antenna 121Rx are of equal length.

[0047] This makes it possible to equalize the phase change of the received signal occurring in the feed lines 141Rx connected to each receiving patch antenna 121Rx belonging to the first antenna group 121. Therefore, phase correction of the received signal in the integrated circuit 131 becomes unnecessary or easy. In addition, it is possible to equalize the loss of the received signal occurring in the feed lines 141Rx connected to each receiving patch antenna 121Rx belonging to the first antenna group 121. Therefore, amplitude correction of the received signal in the integrated circuit 131 becomes unnecessary or easy.

[0048] Furthermore, in the antenna device 1, M belonging to the first antenna group 121 Ｔｘ Of the individual transmitting patch antennas 121Tx, for two or more patch antennas 121Tx connected to the same integrated circuit 131, the feed lines connecting the integrated circuit 131 and each patch antenna 121Tx are of equal length.

[0049] This makes it possible to equalize the phase change of the transmitted signal occurring in the feed lines 141Tx connected to each transmitting patch antenna 121Tx belonging to the first antenna group 121. Therefore, phase correction of the transmitted signal in the integrated circuit 131 becomes unnecessary or easy. In addition, it is possible to equalize the loss of the transmitted signal occurring in the feed lines 141Tx connected to each transmitting patch antenna 121Rx belonging to the first antenna group 121. Therefore, amplitude correction of the transmitted signal in the integrated circuit 131 becomes unnecessary or easy.

[0050] Furthermore, in the antenna device 1, N belonging to the second antenna group 122 Ｒｘ Of the receiving patch antennas 122Rx, for two or more patch antennas 122Rx connected to a single integrated circuit 132, the feed lines 142Rx connecting the integrated circuit and each patch antenna 122Rx are of equal length.

[0051] This makes it possible to equalize the phase change of the received signal occurring in the feed lines 142Rx connected to each receiving patch antenna 122Rx belonging to the second antenna group 122. Therefore, phase correction of the received signal in the integrated circuit 132 becomes unnecessary or easy. In addition, the loss of the received signal occurring in the feed lines 142Rx connected to each receiving patch antenna 122Rx belonging to the second antenna group 122 can be equalized. Therefore, amplitude correction of the received signal in the integrated circuit 132 becomes unnecessary or easy.

[0052] Furthermore, in the antenna device 1, N belonging to the second antenna group 122 Ｔｘ Of the individual transmitting patch antennas 122Tx, for two or more patch antennas 122Tx connected to a single integrated circuit 132, the feed lines 142Tx connecting the integrated circuit 132 and each patch antenna 122Tx are of equal length.

[0053] This makes it possible to equalize the phase change of the transmitted signal occurring in the feed lines 142Tx connected to each transmitting patch antenna 122Tx belonging to the second antenna group 122. Therefore, phase correction of the transmitted signal in the integrated circuit 132 becomes unnecessary or easy. In addition, the loss of the transmitted signal occurring in the feed lines 142Tx connected to each transmitting patch antenna 122Rx belonging to the second antenna group 122 can be equalized. Therefore, amplitude correction of the transmitted signal in the integrated circuit 132 becomes unnecessary or easy.

[0054] From the arrangement of the M+N patch antennas 121Rx, 121Tx, 122Rx, and 122Tx that constitute the array antenna 12, the virtual aperture length D1 of the array antenna 12 in the direction parallel to the first line L1 and the virtual aperture length D2 of the array antenna 12 in the direction parallel to the second line L2 can be calculated. Since the method for calculating the virtual aperture lengths D1 and D2 of the array antenna 12 is well known, its explanation is omitted here.

[0055] As described above, the antenna device 1 can be used as the front end of the radar system. When the antenna device 1 is positioned such that the first straight line L1 coincides with the azimuth direction and the second straight line L2 coincides with the elevation direction, the angular resolution θ1 of the radar system in the azimuth direction can be evaluated using the virtual aperture length D1 of the array antenna 12 in the direction parallel to the first straight line L1, by the formula θ1 = λ / D1. The angular resolution θ2 of the radar system in the elevation direction can be evaluated using the virtual aperture length D2 of the array antenna 12 in the direction parallel to the second straight line L2, by the formula θ2 = λ / D2. Here, λ is the operating wavelength of the radar system, that is, the wavelength of the electromagnetic waves transmitted and received by the antenna device 1.

[0056] When detecting the three-dimensional shape of a target (e.g., a person) placed in a room using such a radar system, it is preferable that the angular resolution θ1 in the azimuth direction and the angular resolution θ2 in the elevation direction are 1.5° = 0.026 rad or less, respectively. Therefore, it is preferable that the virtual aperture length D1 of the array antenna 12 in the direction parallel to the first straight line L1 satisfies the following equation (1), and the virtual aperture length D2 of the array antenna 12 in the direction parallel to the second straight line L2 satisfies the following equation (2).

[0057]

[0058] Furthermore, in the antenna device 1, it is preferable that the total number M + N of patch antennas 121Rx, 121Tx, 122Rx, and 122Tx constituting the array antenna 12 satisfies the following formula (3).

[0059]

[0060] This makes it possible to realize an antenna device 1 with angular resolution comparable to that of a MIMO-ULA (Multi Input Multi Output - Uniform Linear Array) antenna using fewer patch antennas 121Rx, 121Tx, 122Rx, and 122Tx than a MIMO-ULA antenna. Therefore, an antenna device 1 with angular resolution comparable to that of a MIMO-ULA antenna can be manufactured more easily and at a lower cost. Furthermore, the processing load on the IF signal output from the antenna device 1 can be reduced, and the processing speed can be increased (real-time performance can be improved).

[0061] (Configuration of the signal processing device) The configuration of the signal processing device 2 and the information processing device 3 according to one embodiment of the present invention will be described with reference to Figure 2. Figure 2 is a block diagram showing the configuration of the signal processing device 2 and the information processing device 3.

[0062] The signal processing device 2, together with the antenna device 1 and the information processing device 3, constitutes the radar system RS. In this embodiment, the signal provided from the antenna device 1 to the signal processing device 2 is a set of IF signals (signals representing the frequency components of the difference between the transmitted signal and the received signal) generated in the integrated circuits 131 and 132 of the antenna device 1.

[0063] The signal processing device 2 comprises an AD converter 21, a processor 22, and a memory 23. The AD converter 21 is configured to perform AD conversion of an analog signal, which is an IF signal. The processor 22 is configured to perform DOA (Direction of Arrival) estimation by referring to the IF signal, which is a digital signal generated by the AD converter 21, according to the instructions of the program stored in the memory 23, and to generate a three-dimensional image showing the result of the DOA estimation.

[0064] Memory 23 stores V(R, θ, φ) defined by the following equation (4) for each arbitrarily set calculation grid (R, θ, φ). In the following equation (4), A(R, θ, φ) represents the eye response corresponding to the calculation grid (R, θ, φ). Also, s ＾ (R, θ, φ, f Ｒ(R, θ, φ) is the signal waveform of the IF signal pre-calculated using the FMCW (Frequency Modulated Continuous Wave) signal model, and its beat frequency is f, originating from the reflected wave from the target present in the computation grid (R, θ, φ). Ｒ (s) represents the signal waveform of an IF signal where R, θ, φ ＾ In the formula, s is represented by a circumflex accent (^).

[0065]

[0066] The processor 22 refers to the value of V(R, θ, φ) stored in memory 23 and the IF signal obtained from the AD converter 21, and calculates the cross-correlation P(R, θ, φ) according to the following equation (5). In the following equation (5), X ＾ [f Ｒ ～ (R, θ, φ) is an IF signal acquired from the AD converter 21, which originates from the reflected wave from the target present in the calculation grid (R, θ, φ), and has a beat frequency of f Ｒ ～ This shows the result of performing a Range-FFT (Range Fast Fourier Transform) on the IF signal (X ＾ In the formula, ^ and f are above X. Ｒ ～ In the formula, f Ｒ (On top of ~). Also, V － (R, θ, φ) Ｈ This represents the Hermitian transpose of V(R, θ, φ) stored in memory 23 (V － In the equation, V is represented by a minus sign.

[0067]

[0068] The processor 22 further generates a 3D image showing the results of the DOA estimation using the calculated cross-correlation P(R,θ,φ). This 3D image is a 3D image in which the target is represented as a 3D point cloud. For example, it can be generated by defining computation grids (R,θ,φ) where the value of the cross-correlation P(R,θ,φ) exceeds a threshold α as computation grids where the target exists, and computation grids (R,θ,φ) where the value of the cross-correlation P(R,θ,φ) does not exceed the threshold α as computation grids where the target does not exist.

[0069] According to the signal processing device 2, even when the target is located in the vicinity of the antenna device 1, a three-dimensional image that accurately reproduces the shape of the target can be constructed.

[0070] Furthermore, if each part of the target is moving, by taking the Doppler shift into consideration, the cross-correlation P(R, θ, φ) given by equation (5) can be expressed as multiple velocities v １ ,v ２ , ..., v Ｌ It is effective to calculate for each of the following (where L is any natural number greater than or equal to 2). In this case, each velocity v ｋ Cross-correlation P corresponding to (k is any natural number between 1 and L, inclusive) ｋ Let (R, θ, φ) be its velocity v ｋ The corresponding threshold α ｋ By comparing it with, its velocity v ｋ It generates a corresponding 3D image. Then, multiple speeds v １ ,v ２ , ..., v Ｌ By combining the three-dimensional images corresponding to each of these, a three-dimensional image representing the DOA estimation result is generated.

[0071] As an example, consider a human body standing with its arms and legs spread wide. In the cross-correlation P(R, θ, φ), it is expected that peaks will appear where each part of the human body (torso, head, hands, feet, etc.) is present. However, each part of the human body not only forms a signal peak where it is present, but also forms a noise peak where it is not present. In particular, the noise peak formed by the relatively large torso in places where the torso is not present may be higher than the signal peak formed by the relatively small head, hands, and feet in places where the head, hands, and feet are present.

[0072] In such cases, a configuration that compares a single cross-correlation P(R, θ, φ) with a single threshold α cannot correctly reproduce the target's morphology (posture). This is because if the threshold α is set high enough to avoid detecting the peaks formed as noise by the torso, the peaks formed as signals by the head, hands, and feet cannot be detected (the areas where the target exists are not recognized as part of the target). Conversely, if the threshold α is set low enough to detect the peaks formed as signals by the head, hands, and feet, the peaks formed as noise by the torso will be detected (the areas where the target does not exist are recognized as part of the target).

[0073] On the other hand, each speed v ｋ Corresponding cross-correlation P ｋ Let (R, θ, φ) be its velocity v ｋに Corresponding threshold α ｋ In a configuration compared to this, the target shape can be accurately reproduced. This is because each part of the human body usually has a different velocity. For simplicity, let's set the velocity of the torso to v １ And the speed of the head, hands, and feet is v ２ (≠v １ ) Let's assume that the velocity v １ Corresponding cross-correlation P １At (R, θ, φ), peaks appear as both signal and noise generated by the torso, but no peaks appear as either signal or noise generated by the head, arms, or legs. On the other hand, velocity v ２ Corresponding cross-correlation P ２ At (R, θ, φ), peaks appear as signals formed by the head, hands, and feet, but no peaks appear as signals or noise formed by the torso. Therefore, the cross-correlation P １ Threshold α to compare with (R, θ, φ) １ Setting the value of P to a higher level allows for accurate detection of the location of the torso, and simultaneously, the cross-correlation P ２ Threshold α to compare with (R, θ, φ) ２ By setting the value to a lower level, the locations of the head, hands, and feet can be detected accurately and completely.

[0074] The information processing device 3, together with the antenna device 1 and the signal processing device 2, constitutes the radar system RS. In this embodiment, the signal provided from the signal processing device 2 to the information processing device 3 is a three-dimensional image generated in the processor 22 of the signal processing device 2.

[0075] The information processing device 3 comprises a processor 31 and a memory 32. The processor 31 performs information processing according to the shape of the target by referring to the three-dimensional image generated in the signal processing device 2, in accordance with the instructions of the program stored in the memory 32.

[0076] The 3D image generated by the signal processing device 2 represents the target as a 3D point cloud (a collection of computational grids where the presence of the target is determined). Therefore, it is suitable for the user to visually identify the shape of the target, but it is not suitable for the processor 31 to identify the shape of the target through information processing.

[0077] Therefore, the information processing device 3 uses a model that represents the target's morphology using multiple parameters to identify the target's morphology. In this case, the processor 31 determines the values ​​of the multiple parameters that represent the target's morphology in such a way that it best approximates the three-dimensional point cloud represented by the three-dimensional image generated by the signal processing device 2. This makes it possible to perform information processing according to the target's morphology by referring to the determined parameter values.

[0078] When the target is the human body, for example, as shown in Figure 3, a model that represents the posture of the human body using the positions of 12 nodes can be used to identify the posture of the human body. In this model, these 12 nodes consist of two nodes corresponding to the tips of the left and right hands, two nodes corresponding to the left and right elbows, two nodes corresponding to the base of the left and right hands, two nodes corresponding to the tips of the left and right feet, two nodes corresponding to the left and right knees, and two nodes corresponding to the base of the left and right feet. In this case, the processor 31 determines the positions of these 12 nodes in order to best approximate the 3D point cloud represented by the 3D image generated by the signal processing device 2. Then, the processor 31 performs information processing according to the posture of the human body by referring to the positions of these 12 nodes. An example of information processing according to the posture of the human body is the issuance of an alarm. In this case, the processor 31 refers to the positions of these 12 nodes to determine whether the posture of the human body corresponds to a posture that suggests a dangerous situation (for example, the posture when lying down), and if it determines that it does, it issues an alarm.

[0079] Furthermore, the information processing device 3 may be used in conjunction with the signal processing device 2, and may or may not be a component of the radar system RS. In other words, the information processing device 3 can be implemented independently of the radar system RS.

[0080] (Example) An embodiment of the antenna device 1 will be described with reference to Figure 4.

[0081] First, an antenna device 1 was created by arranging the patch antennas 121Rx, 121Tx, 122Rx, and 122Tx that constitute the array antenna 12 as shown in Figure 1. Then, a human body standing with its arms and legs spread wide in an anechoic chamber measuring 3m (horizontal) x 2.5m (vertical) x 8m (depth) was detected by the radar system RS, which includes the antenna device 1 and the signal processing device 2. As a result, the signal processing device 2 included in the radar system RS generated the three-dimensional image shown in Figure 4. Note that in the signal processing device 2, each velocity v ｋ Corresponding cross-correlation P ｋ Let (R, θ, φ) be its velocity v ｋに Corresponding threshold α ｋ A configuration was adopted that allows for comparison. The three-dimensional image shown in Figure 3 was obtained by synthesizing three-dimensional images corresponding to each velocity vk. In Figure 4, a model representing the posture of the human body with the positions of 12 nodes is shown, along with a model that best approximates the three-dimensional point cloud represented by this three-dimensional image. This confirmed that the radar system RS, including the antenna device 1 and the signal processing device 2, can appropriately detect the human body, including its posture.

[0082] (Summary) An antenna device according to embodiment 1 of the present invention comprises a substrate and an array antenna consisting of a plurality of patch antennas formed on one main surface of the substrate, wherein the array antenna is composed of a first antenna group consisting of M patch antennas (M is any natural number of 3 or more) arranged in one or two rows along a first straight line, and a second antenna group consisting of N patch antennas (N is any natural number of 3 or more) arranged in one or two rows along a second straight line perpendicular to the first straight line, wherein the angle between the longitudinal axis of each patch antenna belonging to the first antenna group and the first straight line is a common angle greater than 0° and less than 180°, and the angle between the longitudinal axis of each patch antenna belonging to the second antenna group and the second straight line is a common angle greater than 90° and less than 270°.

[0083] The antenna device according to Embodiment 2 of the present invention is such that, taking the wavelength of the electromagnetic wave transmitted and received by the array antenna as λ, the virtual aperture length D1 of the array antenna in the direction parallel to the first straight line satisfies the following formula (1), and the virtual aperture length D2 of the array antenna in the direction parallel to the second straight line satisfies the following formula (2). It is the antenna device according to Embodiment 1, characterized in that.

[0084]

[0085] The antenna device according to Embodiment 3 of the present invention is such that, taking the wavelength of the electromagnetic wave transmitted and received by the array antenna as λ, the virtual aperture length D1 of the array antenna in the direction parallel to the first straight line and the virtual aperture length D2 of the array antenna in the direction parallel to the second straight line satisfy the following formula (3). It is the antenna device according to Embodiment 1 or 2, characterized in that.

[0086]

[0087] The antenna device according to Embodiment 4 of the present invention is such that the first antenna group includes M Ｒｘ (M Ｒｘ is a natural number of 2 or more and M - 1 or less) receiving patch antennas arranged on the first straight line, and M Ｔｘ = M - M Ｒｘ transmitting patch antennas arranged on another straight line parallel to the first straight line, and the second antenna group includes N Ｒｘ (N Ｒｘ is a natural number of 2 or more and N - 1 or less) receiving patch antennas arranged on the second straight line, and N Ｔｘ = N - N Ｒｘ transmitting patch antennas arranged on another straight line parallel to the second straight line. It is the antenna device according to any one of Embodiments 1 to 3, characterized in that.

[0088] The antenna device according to Embodiment 5 of the present invention is such that M belonging to the first antenna group ＲｘAmong the patch antennas for reception, for two or more patch antennas for reception connected to the same integrated circuit, the feeding lines connecting the integrated circuit and each patch antenna for reception are equal in length to each other, and M belonging to the first antenna group Ｔｘ Among the patch antennas for transmission, for two or more patch antennas for transmission connected to the same integrated circuit, the feeding lines connecting the integrated circuit and each patch antenna for transmission are equal in length to each other, and N belonging to the second antenna group Ｒｘ Among the patch antennas for reception, for two or more patch antennas for reception connected to a single integrated circuit, the feeding lines connecting the integrated circuit and each patch antenna for reception are equal in length to each other, and N belonging to the second antenna group Ｔｘ Among the patch antennas for transmission, for two or more patch antennas for transmission connected to a single integrated circuit, the feeding lines connecting the integrated circuit and each patch antenna for transmission are equal in length to each other, which is the antenna device according to aspect 4 characterized by this.

[0089] The antenna device according to aspect 6 of the present invention is such that the angle formed by the longitudinal direction of each patch antenna belonging to the first antenna group and the first straight line is a common angle of 20° or more and 160° or less, and the angle formed by the longitudinal direction of each patch antenna belonging to the second antenna group and the second straight line is a common angle of 110° or more and 250° or less, which is the antenna device according to any one of aspects 1 to 5 characterized by this.

[0090] The signal processing device according to aspect 7 of the present invention includes a memory in which the value of V(R, θ, φ) defined by the following formula (4) is stored for each calculation grid (R, θ, φ), and the value of V(R, θ, φ) stored in the memory, and an IF signal acquired from an antenna device, and a processor that calculates the cross-correlation P(R, θ, φ) according to the following formula (5), which is a signal processing device characterized by this.

[0091]

[0092] Here, A(R, θ, φ) represents the iris response corresponding to the calculation grid (R, θ, φ), and s ＾ (R, θ, φ, fＲ (R, θ, φ) is the signal waveform of the IF signal pre-calculated using the FMCW (Frequency Modulated Continuous Wave) signal model, and its beat frequency is f, originating from the reflected wave from the target present in the computation grid (R, θ, φ). Ｒ (s) represents the signal waveform of an IF signal where R, θ, φ ＾ In the formula, s is represented by a circumflex accent (^).

[0093]

[0094] Here, X ＾ [f Ｒ ～ (R, θ, φ) is an IF signal acquired from the antenna device, which originates from reflected waves from targets present in the calculation grid (R, θ, φ), and has a beat frequency of f Ｒ ～ This shows the result of performing a Range-FFT (Range Fast Fourier Transform) on the IF signal (X ＾ In the formula, ^ and f are above X. Ｒ ～ In the formula, f Ｒ On top of ~), V － (R, θ, φ) Ｈ This represents the Hermitian transpose of the value of V(R, θ, φ) stored in the memory (V － In the equation, V is represented by a minus sign.

[0095] The signal processing device according to embodiment 8 of the present invention is a signal processing device according to embodiment 7, characterized in that, in the calculation process, the processor calculates a cross correlation P(R, θ, φ) corresponding to each of a plurality of speeds according to formula (5), the processor further performs a generation process to generate a three-dimensional image that represents the portion of the target having the speed as a three-dimensional point cloud by comparing the cross correlation P(R, θ, φ) corresponding to each speed with a threshold corresponding to the speed, and a synthesis process to generate a three-dimensional image that represents the entire target as a three-dimensional point cloud by combining the three-dimensional images corresponding to each speed generated in the generation process.

[0096] A radar system according to aspect 9 of the present invention is a radar system characterized by comprising an antenna device described in any one of aspects 1 to 6, and a signal processing device for processing IF signals generated by the antenna device.

[0097] A radar system according to aspect 10 of the present invention is a radar system according to aspect 9, characterized in that the signal processing device is the signal processing device described in aspect 7 or 8.

[0098] A radar system according to aspect 11 of the present invention is a radar system characterized by comprising an antenna device and a signal processing device according to aspect 7 or 8 for processing IF signals generated by the antenna device.

[0099] A radar system according to aspect 12 of the present invention comprises an antenna device, a signal processing device according to aspect 8 that processes an IF signal generated by the antenna device, and an information processing device that processes a three-dimensional image generated by the signal processing device using a model that represents the shape of a target with a plurality of parameters, wherein the information processing device includes a processor that determines the values ​​of the plurality of parameters so that the model best approximates the three-dimensional point cloud represented by the three-dimensional image generated by the signal processing device, and performs information processing according to the shape of the target by referring to the determined values ​​of the plurality of parameters.

[0100] The signal processing device according to aspect 13 of the present invention is an information processing device that processes a three-dimensional image generated by the signal processing device described in aspect 8 using a model that represents the shape of a target with a plurality of parameters, and is characterized by comprising a processor that determines the values ​​of the plurality of parameters so that the model best approximates the three-dimensional point cloud represented by the three-dimensional image generated by the signal processing device, and performs information processing according to the shape of the target by referring to the determined values ​​of the plurality of parameters.

[0101] (Additional Notes) The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in each of the embodiments described above are also included in the technical scope of the present invention.

[0102] 1 Antenna device 11 Circuit board 12 Array antenna 121 First antenna group 121Rx Patch antenna (for receiving) 121Tx Patch antenna (for transmitting) 122 Second antenna group 122Rx Patch antenna (for receiving) 122Tx Patch antenna (for transmitting) 131, 132 Integrated circuit 141Rx Feed line (for receiving) 141Tx Feed line (for transmitting) 142Rx Feed line (for receiving) 142Tx Feed line (for transmitting) 2 Signal processing device 21 AD converter 22 Processor 23 Memory RS Radar system 3 Information processing device 31 Processor 32 Memory

Claims

1. An antenna device comprising a substrate and an array antenna consisting of a plurality of patch antennas formed on one main surface of the substrate, wherein the array antenna is composed of a first antenna group consisting of M patch antennas (M is any natural number of 3 or more) arranged in one or two rows along a first straight line, and a second antenna group consisting of N patch antennas (N is any natural number of 3 or more) arranged in one or two rows along a second straight line perpendicular to the first straight line, wherein the angle between the longitudinal axis of each patch antenna belonging to the first antenna group and the first straight line is a common angle greater than 0° and less than 180°, and the angle between the longitudinal axis of each patch antenna belonging to the second antenna group and the second straight line is a common angle greater than 90° and less than 270°.

2. The antenna device according to claim 1, wherein, with respect to the wavelength of the electromagnetic waves transmitted and received by the array antenna being λ, the virtual aperture length D1 of the array antenna in the direction parallel to the first straight line satisfies the following formula (1), and the virtual aperture length D2 of the array antenna in the direction parallel to the second straight line satisfies the following formula (2).

3. The antenna device according to claim 1 or 2, characterized in that, with λ being the wavelength of the electromagnetic waves transmitted and received by the array antenna, the virtual aperture length D1 of the array antenna in the direction parallel to the first straight line and the virtual aperture length D2 of the array antenna in the direction parallel to the second straight line satisfy the following formula (3).

4. The first antenna group is arranged on the first straight line M Ｒｘ pieces (M Ｒｘ A patch antenna for receiving (where is a natural number between 2 and M-1), and M positioned on another straight line parallel to the first straight line. Ｔｘ = M - M Ｒｘ The second antenna group consists of a patch antenna for transmission, and the second antenna group is arranged on the second straight line N Ｒｘ pieces (N Ｒｘ A patch antenna for receiving (where is a natural number between 2 and N-1), and N arranged on another straight line parallel to the second straight line. Ｔｘ = N - N Ｒｘ An antenna device according to any one of claims 1 to 3, characterized by comprising a patch antenna for transmission.

5. Among the M reception patch antennas belonging to the first antenna group, for two or more reception patch antennas connected to the same integrated circuit, the feeding lines connecting the integrated circuit and each reception patch antenna are equal in length to each other. Among the M Ｒｘ transmission patch antennas belonging to the first antenna group, for two or more transmission patch antennas connected to the same integrated circuit, the feeding lines connecting the integrated circuit and each transmission patch antenna are equal in length to each other. Among the N Ｔｘ reception patch antennas belonging to the second antenna group, for two or more reception patch antennas connected to a single integrated circuit, the feeding lines connecting the integrated circuit and each reception patch antenna are equal in length to each other. Among the N Ｒｘ transmission patch antennas belonging to the second antenna group, for two or more transmission patch antennas connected to a single integrated circuit, the feeding lines connecting the integrated circuit and each transmission patch antenna are equal in length to each other. The antenna device according to claim 4, characterized in that Ｔｘ this is the case.

6. The antenna device according to any one of claims 1 to 5, characterized in that the angle between the longitudinal direction of each patch antenna belonging to the first antenna group and the first straight line is a common angle of 20° or more and 160° or less, and the angle between the longitudinal direction of each patch antenna belonging to the second antenna group and the second straight line is a common angle of 110° or more and 250° or less.

7. A signal processing device characterized by comprising: a memory storing the value of V(R, θ, φ) defined by the following formula (4) for each calculation grid (R, θ, φ); and a processor that performs a calculation process to calculate the cross-correlation P(R, θ, φ) according to the following formula (5), by referring to the value of V(R, θ, φ) stored in the memory and the IF signal acquired from the antenna device. Here, A(R, θ, φ) represents the eye response corresponding to the computation grid (R, θ, φ), and s ＾ (R, θ, φ, f Ｒ (R, θ, φ) is the signal waveform of the IF signal pre-calculated using the FMCW (Frequency Modulated Continuous Wave) signal model, and its beat frequency is f, originating from the reflected wave from the target present in the computation grid (R, θ, φ). Ｒ (s) represents the signal waveform of an IF signal where R, θ, φ ＾ In the formula, s is represented by a circumflex accent (^). Here, X ＾ [f Ｒ ～ (R, θ, φ) is an IF signal acquired from the antenna device, which originates from reflected waves from targets present in the calculation grid (R, θ, φ), and has a beat frequency of f Ｒ ～ This shows the result of performing a Range-FFT (Range Fast Fourier Transform) on the IF signal (X ＾ In the formula, ^ and f are above X. Ｒ ～ In the formula, f Ｒ On top of ~), V － (R, θ, φ) Ｈ This represents the Hermitian transpose of the value of V(R, θ, φ) stored in the memory (V － (In the equation, V is represented by a minus sign.) 8. The signal processing apparatus according to claim 7, wherein in the calculation process, the processor calculates a cross-correlation P(R, θ, φ) corresponding to each of a plurality of speeds according to formula (5), and the processor further performs a generation process to generate a three-dimensional image that represents the portion of the target having the speed as a three-dimensional point cloud by comparing the cross-correlation P(R, θ, φ) corresponding to each speed with a threshold corresponding to the speed, and a synthesis process to generate a three-dimensional image that represents the entire target as a three-dimensional point cloud by synthesizing the three-dimensional images corresponding to each speed generated in the generation process.

9. A radar system comprising an antenna device according to any one of claims 1 to 6, and a signal processing device for processing IF signals generated by the antenna device.

10. The radar system according to claim 9, characterized in that the signal processing device is the signal processing device described in claim 7.

11. A radar system comprising an antenna device and a signal processing device according to claim 7 or 8 for processing the IF signal generated by the antenna device.

12. A radar system comprising: an antenna device; a signal processing device according to claim 8 for processing an IF signal generated by the antenna device; and an information processing device for processing a three-dimensional image generated by the signal processing device using a model that represents the shape of a target with a plurality of parameters, wherein the information processing device includes a processor that determines the values ​​of the plurality of parameters so that the model best approximates the three-dimensional point cloud represented by the three-dimensional image generated by the signal processing device, and performs information processing according to the shape of the target by referring to the determined values ​​of the plurality of parameters.

13. An information processing device that processes a three-dimensional image generated by a signal processing device according to claim 8 using a model that represents the morphology of a target using a plurality of parameters, the information processing device comprising a processor that determines the values ​​of the plurality of parameters so that the model best approximates the three-dimensional point cloud represented by the three-dimensional image generated by the signal processing device, and performs information processing according to the morphology of the target by referring to the determined values ​​of the plurality of parameters.

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