Laser device

Abstract

To provide a radar device capable of properly detecting information relating to a target in both a first direction and a second direction while suppressing an increase in the number of antenna elements for transmission.SOLUTION: A radar device 1 detects the bearing of a target in a horizontal direction U on the basis of reception results of a radio wave by a first element array composed of a plurality of antenna elements for transmission that are arranged in a row in a horizontal direction U and a virtual antenna using a plurality of antenna elements for reception. The radar device 1 also detects the bearing of the target in a vertical direction V on the basis of reception results of a radio wave by a second element array composed of a plurality of antenna elements for transmission that are arranged in a row in the vertical direction V and a virtual array antenna using a plurality of antenna elements for reception. A transmission antenna group 3 is such that a plurality of antenna elements for transmission are arranged so that the number of antenna elements for transmission constituting the second element array is larger than the number in the first element array.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a radar device. [Background technology]

[0002] Conventionally, there is known a radar device that detects information about a target in both the horizontal and vertical directions by using MIMO array technology that uses multiple transmitting antennas and multiple receiving antennas arranged in the horizontal and vertical directions (see, for example, Patent Document 1). Note that MIMO is an abbreviation for Multi Input Multi Output.

[0003] In the radar device described in Patent Document 1, the number of element rows, each of which is made up of two transmitting antenna elements arranged side by side in the horizontal direction, is set to be equal to the number of transmitting antenna elements arranged side by side in the vertical direction. Specifically, Patent Document 1 discloses an antenna configuration in which four element rows, each of which is made up of two transmitting antenna elements arranged side by side in the horizontal direction, are arranged side by side in the vertical direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7027579 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the number of transmitting antenna elements used in a radar device may be limited in view of the specifications of the IC to be mounted, limitations on the number of parts, heat management, and the like.

[0006] If the number of transmitting antenna elements is limited, for example, in the antenna configuration disclosed in Patent Document 1, many transmitting antenna elements are required to be arranged in the horizontal direction, and the number of transmitting antenna elements arranged in the vertical direction is reduced. Limiting the number of transmitting antenna elements arranged in the vertical direction is not preferable because it leads to, for example, a lack of resolution for detecting information about a target in the vertical direction. This can occur not only when information about a target is detected in both the horizontal and vertical directions, but also when information about a target is detected in two different directions.

[0007] An object of the present disclosure is to provide a radar device capable of appropriately detecting information relating to a target in both a predetermined first direction and a second direction intersecting the first direction, while suppressing an increase in the number of transmitting antenna elements. [Means for solving the problem]

[0008] The invention described in claim 1 is A radar device that detects targets using radio waves, A transmitting antenna group (3) including a plurality of transmitting antenna elements; A receiving antenna group (4) including a plurality of receiving antenna elements; a first detection unit (61) that detects information about a target in a first direction based on a reception result of a reflected wave corresponding to a transmission wave from a transmitting antenna group in a first virtual array antenna using a first element row consisting of a plurality of transmitting antenna elements arranged in a predetermined first direction and a plurality of receiving antenna elements arranged in the first direction; a second detection unit (62) that detects information about a target in the second direction based on a reception result of a reflected wave at a second element row consisting of a plurality of transmitting antenna elements arranged in a second direction intersecting the first direction and a second virtual array antenna using a plurality of receiving antenna elements arranged in the second direction, In the transmitting antenna group, a plurality of transmitting antenna elements are arranged such that the number of transmitting antenna elements constituting the second element array is greater than the number of transmitting antenna elements constituting the first element array.

[0009] In Patent Document 1, the number of element rows each consisting of two transmitting antenna elements arranged side by side in a first direction is set to be the same as the number of transmitting antenna elements arranged side by side in a second direction (four in Patent Document 1). In such an antenna configuration, the number of transmitting antenna elements arranged side by side in the first direction increases, so that the number of transmitting antenna elements arranged side by side in the second direction is greatly limited.

[0010] In contrast, in the radar device of the present disclosure, the multiple transmitting antenna elements are arranged so that the number of multiple transmitting antenna elements arranged in the second direction is greater than the number of first element rows used to detect information related to targets in the first direction. In such an antenna configuration, the number of multiple transmitting antenna elements arranged in the second direction is increased by the amount reduced, so that it is possible to ensure the antenna aperture length in the second direction and improve the resolution in the second direction.

[0011] Therefore, the radar device according to the present disclosure can appropriately detect information relating to targets in both a first direction and a second direction intersecting the first direction, while suppressing an increase in the number of transmitting antenna elements.

[0012] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and specific components described in the embodiments described below. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram of a radar device according to a first embodiment. [Diagram 2] 2 is a schematic diagram showing a group of transmitting antennas and a group of receiving antennas in the radar device according to the first embodiment. FIG. [Diagram 3] FIG. 2 is an explanatory diagram for explaining a virtual array antenna in the radar device according to the first embodiment. [Figure 4] 5 is a flowchart showing the flow of a target detection process executed by a control unit of the radar device according to the first embodiment. [Diagram 5] FIG. 2 is an explanatory diagram for explaining positions and power levels of three targets in one embodiment. [Figure 6] FIG. 4 is a spectrum diagram showing a simulation result of azimuth estimation in the horizontal direction using a single transmitting antenna element in the radar device according to the first embodiment. [Figure 7] FIG. 4 is a spectrum diagram showing a simulation result of azimuth estimation in the horizontal direction using a plurality of transmitting antenna elements in the radar device according to the first embodiment. [Figure 8] FIG. 2 is a spectrum diagram showing a simulation result when the vertical azimuth of a target is estimated in the azimuth corresponding to the first peak detected in the horizontal azimuth estimation in the radar device according to the first embodiment. [Figure 9] FIG. 11 is a spectrum diagram showing a simulation result when the vertical azimuth of a target is estimated in the azimuth corresponding to the second peak detected in the horizontal azimuth estimation in the radar device according to the first embodiment. [Figure 10] 4 is a schematic diagram showing a group of transmitting antennas and a group of receiving antennas in a radar device serving as a comparative example of the first embodiment. FIG. [Figure 11] FIG. 11 is a spectrum diagram showing a simulation result of estimating a horizontal direction using a plurality of transmitting antenna elements in a radar device of a comparative example. [Figure 12] FIG. 11 is a spectrum diagram showing a simulation result when the vertical azimuth of a target is estimated in the azimuth corresponding to the first peak detected in the horizontal azimuth estimation in the radar device of the comparative example. [Figure 13] FIG. 11 is a spectrum diagram showing a simulation result when the vertical azimuth of a target is estimated in the azimuth corresponding to the second peak detected in the horizontal azimuth estimation in the radar device of the comparative example. [Figure 14] 10 is a schematic diagram showing a group of transmitting antennas and a group of receiving antennas in a radar device according to a second embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, the same reference numerals are used for parts that are the same as or equivalent to those described in the preceding embodiments, and the description thereof may be omitted. In addition, in the embodiments, when only a part of the components is described, the components described in the preceding embodiments can be applied to the other parts of the components. In the following embodiments, each embodiment can be partially combined with each other, even if not specifically stated, as long as it does not cause any trouble in combination.

[0015] (First embodiment) The present embodiment will be described with reference to Fig. 1 to Fig. 13. In the present embodiment, an example will be described in which a radar device 1 of the present disclosure is applied to a target detection device that is mounted on a vehicle and detects various targets existing around the vehicle.

[0016] The radar device 1 emits radio waves ahead of the vehicle and receives radio waves reflected by a target ahead of the vehicle to determine the distance to the target, the relative speed with respect to the vehicle, the direction with respect to the vehicle, etc.

[0017] The radar device 1 employs the FMCW method as a signal modulation method. The radar device 1 operates at a radio frequency in a frequency band corresponding to millimeter waves (e.g., 76.5 GHz). Note that the operating frequency of the radio waves transmitted and received by the radar device 1 is not limited to a frequency corresponding to millimeter waves, and may be a frequency other than millimeter waves.

[0018] As shown in FIG. 1, the radar device 1 includes a transmitter 2, a transmitting antenna group 3 including a plurality of actual transmitting antenna elements, a receiving antenna group 4 including a plurality of actual receiving antenna elements, a receiver 5, and a control unit 6.

[0019] The transmitter 2 generates a signal to be transmitted from the transmitting antenna group 3 and transmits it to the transmitting antenna group 3. The transmitter 2 includes an oscillator 21 and a modulator 22. The transmitter 2 generates a local signal and transmits the generated local signal to the receiver 5. The transmitter 2 also generates a chirp signal whose frequency changes continuously and provides the generated chirp signal to the transmitting antenna group 3. The transmitting antenna group 3 then transmits radio waves (i.e., transmission waves) corresponding to the chirp signal provided from the transmitter 2 toward the front of the vehicle.

[0020] The transmitting antenna group 3 in this example has eight actual transmitting antenna elements Tx1 to Tx3, Tx4 (Tx41, Tx42), and Tx5 to Tx7. The eight transmitting antenna elements Tx1 to Tx3, Tx41, Tx42, and Tx5 to Tx7 constituting the transmitting antenna group 3 are arranged side by side in the horizontal direction U and the vertical direction V in a state in which the radar device 1 is mounted on a vehicle, as shown in Fig. 2. In this embodiment, the horizontal direction U corresponding to the width direction of the vehicle corresponds to the "predetermined first direction", and the vertical direction V corresponding to the height direction of the vehicle corresponds to the "second direction" intersecting the "first direction".

[0021] In the transmitting antenna group 3, seven transmitting antenna elements Tx1 to Tx3, Tx41, and Tx5 to Tx7 are arranged at predetermined intervals along the vertical direction V. The transmitting antenna elements Tx1 to Tx3, Tx41, and Tx5 to Tx7 arranged in the vertical direction V are arranged at intervals of "1dv", which is one time a predetermined vertical reference distance dv. In this embodiment, the transmitting antenna elements Tx1 to Tx3, Tx41, and Tx5 to Tx7 arranged in the vertical direction V constitute a "second element row" consisting of antenna elements arranged in the "second direction" in the transmitting antenna group 3.

[0022] Here, the interval between the transmitting antenna elements in the vertical direction V may be strictly a multiple of the vertical reference distance dv, or may include an error that is generally acceptable in the technical field to which the technology of the present disclosure belongs and does not go against the spirit of the technology of the present disclosure. The same applies to the intervals between the receiving antenna elements Rx11 to Rx18 and Rx21 to Rx28 aligned in the vertical direction V.

[0023] The vertical reference distance dv in this example is set so as to satisfy the following formula F1 when the detection range of the radar device 1 is "±1 / 2·φfov". In this embodiment, φfov is set to "40°" and the vertical reference distance dv is set to "1 / 2·λ", where λ is the wavelength of the radio wave.

[0024] 1 / sin(φfov / 180 π) 2 <dv ···(F1) In the transmitting antenna group 3, the transmitting antenna element Tx42 is arranged at a predetermined interval in the horizontal direction U with respect to the transmitting antenna element Tx41 which is located approximately in the center of the vertical direction V. The transmitting antenna elements Tx41 and Tx42 arranged side by side in the horizontal direction U are arranged at an interval of "8dh", which is eight times the predetermined horizontal reference distance dh.

[0025] In the transmitting antenna group 3 of this embodiment, transmitting antenna elements Tx1 to Tx3 and Tx5 to Tx7 other than transmitting antenna elements Tx41 and Tx42 located approximately in the center of the vertical direction V are not provided with opposing antenna elements in the horizontal direction U. In this embodiment, the transmitting antenna elements Tx41 and Tx42 aligned in the horizontal direction U constitute a "first element row" in the transmitting antenna group 3 made up of antenna elements aligned in a "first direction".

[0026] Here, the interval between the transmitting antenna elements Tx41, Tx42 may be strictly a multiple of the horizontal reference distance dh, or may include an error that is generally acceptable in the technical field to which the technology of the present disclosure belongs and does not go against the spirit of the technology of the present disclosure. The same applies to the interval between the receiving antenna elements Rx11 to Rx18 and Rx21 to Rx28 aligned in the horizontal direction U.

[0027] The horizontal reference distance dh in this example is set so as to satisfy the following formula F2 when the detection range of the radar device 1 is "±1 / 2·θfov". In this embodiment, θfov is set to "180°" and the horizontal reference distance dh is set to "1 / 2·λ", where λ is the wavelength of the radio wave.

[0028] 1 / sin(θfov / 180 π) 2 <dh ···(F2) In the transmitting antenna group 3 configured in this manner, the transmitting antenna elements are arranged so that the number of transmitting antenna elements Tx1-Tx3, Tx41, and Tx5-Tx7 constituting the "second element array" is greater than the number in the "first element array". In the transmitting antenna group 3 of this embodiment, the transmitting antenna elements are arranged so that the number of transmitting antenna elements Tx1-Tx3, Tx41, and Tx5-Tx7 constituting the "second element array" is "7", while the number of the "first element array" is "1".

[0029] The receiving antenna group 4 receives, as reflected waves, radio waves transmitted from the transmitting antenna group 3 and reflected by a target. In this example, the receiving antenna group 4 is composed of 16 actual receiving antenna elements Rx11-Rx18, Rx21-Rx28. The 16 receiving antenna elements Rx11-Rx18, Rx21-28 constituting the receiving antenna group 4 are arranged in a row in the horizontal direction U and the vertical direction V when the radar device 1 is mounted on a vehicle.

[0030] Specifically, the receiving antenna group 4 has a first receiving element row Rx1 consisting of eight receiving antenna elements Rx11-Rx18 lined up along the horizontal direction U at a position close to the transmitting antenna element Tx1 which is one end of the transmitting antenna group 3 in the vertical direction V. The receiving antenna group 4 also has a second receiving element row Rx2 consisting of eight receiving antenna elements Rx21-Rx28 lined up along the horizontal direction U at a position close to the transmitting antenna element Tx7 which is the other end of the transmitting antenna group 3 in the vertical direction V.

[0031] The receiving antenna elements Rx11-Rx18 constituting the first receiving element array Rx1 are spaced apart by a distance "dh" which is one time the horizontal reference distance dh. The receiving antenna elements Rx21-Rx28 constituting the second receiving element array Rx2 are spaced apart by a distance "dh" which is one time the horizontal reference distance dh.

[0032] The first receiving element array Rx1 and the second receiving element array Rx2 are arranged to face each other in the vertical direction V. The first receiving element array Rx1 and the second receiving element array Rx2 are arranged at an interval of "7dv", which is seven times the vertical reference distance dv. The first receiving element array Rx1 is arranged at an interval of "0.5dv" in the vertical direction V from the transmitting antenna element Tx1, which is one end of the transmitting antenna group 3 in the vertical direction V. The second receiving element array Rx2 is arranged at an interval of "0.5dv" in the vertical direction V from the transmitting antenna element Tx7, which is the other end of the transmitting antenna group 3 in the vertical direction V.

[0033] Here, the MMIC used in the radar device 1 has, for example, eight channels in total for transmission and reception. The radar device 1 of this embodiment requires eight channels for transmission and 16 channels for reception, so it can be realized with three MMICs. Note that MMIC is an abbreviation for Monolithic Microwave Integrated Circuit.

[0034] The receiving unit 5 generates a beat signal based on the reception signals received by the receiving antenna group 4 and the local signal transmitted from the transmitting unit 2, samples the beat signal, and provides it to the control unit 6. Although not shown, the receiving unit 5 is configured to include a mixer, an amplifier, an AD converter, etc.

[0035] The control unit 6 is an electronic control device mainly composed of a microcomputer equipped with a processor and a memory M. The memory M is, for example, a ROM, a RAM, etc. Various functions of the microcomputer are realized by the processor executing a program stored in a non-transient physical storage medium.

[0036] The control unit 6 detects information about a target in two mutually intersecting directions using a plurality of transmitting antenna elements Tx1-Tx3, Tx41, Tx42, Tx5-Tx8 and receiving antenna elements Rx11-Rx18, Rx21-Rx28 arranged in the horizontal direction U and vertical direction V. The control unit 6 of this embodiment detects the distance from the radar device 1 to the target, the relative speed between the radar device 1 and the target, and the azimuth of the target with respect to the radar device 1 as information about the target.

[0037] For example, the control unit 6 detects the azimuth of the target in the horizontal direction U using antenna elements arranged in the horizontal direction U, and detects the azimuth of the target in the vertical direction V based on a spectrum signal corresponding to the detected azimuth, thereby detecting the azimuth of the target in two intersecting directions.

[0038] The radar device 1 of this embodiment has a plurality of transmitting antenna elements Tx41, Tx42 aligned in the horizontal direction U, and a plurality of receiving antenna elements Rx11-Rx18, Rx21-Rx28 aligned in the horizontal direction U. The control unit 6 detects the azimuth of the target with respect to the horizontal direction U using a "first virtual array antenna" including the transmitting antenna elements Tx41, Tx42 and the plurality of receiving antenna elements Rx11-Rx18, Rx21-Rx28 aligned in the horizontal direction U.

[0039] Moreover, the radar device 1 of this embodiment has a plurality of transmitting antenna elements Tx1-Tx3, Tx41, Tx5-Tx7 aligned in the vertical direction V and a plurality of receiving antenna elements Rx11-Rx18, Rx21-Rx28 aligned in the vertical direction V. The control unit 6 detects the azimuth of a target with respect to the vertical direction V using a "second virtual array antenna" including the transmitting antenna elements Tx1-Tx3, Tx41, Tx5-Tx7 and the plurality of receiving antenna elements Rx11-Rx18, Rx21-Rx28 aligned in the vertical direction V. In this embodiment, the configuration in the control unit 6 for detecting information related to a target in the horizontal direction U corresponds to the "first detection unit 61," and the configuration in the control unit 6 for detecting information related to a target with respect to the vertical direction V corresponds to the "second detection unit 62."

[0040] The first virtual array antenna of this embodiment has an antenna configuration in which eight receiving antenna elements Rx11-Rx18, Rx21-Rx28 are added with eight virtual antenna elements by MIMO array technology, as shown as "horizontal MIMO" in Fig. 3. The first virtual array antenna is obtained by receiving radio waves transmitted from two transmitting antenna elements Tx41, Tx42 at eight receiving antenna elements Rx11-Rx18, Rx21-Rx28 and performing predetermined signal processing on the received signals.

[0041] The first virtual array antenna has an antenna aperture length of "16dh". On the other hand, the antenna aperture length of the SIMO is "8dh", which is half the antenna aperture length of the first virtual array antenna. The first virtual array antenna of this embodiment has an antenna configuration in which the antenna elements are equally spaced. Note that SIMO is an abbreviation for Single Input Multi Output.

[0042] Moreover, the second virtual array antenna of this embodiment has an antenna configuration having 14 virtual antenna elements by MIMO array technology, as shown as "Vertical MIMO" in Fig. 3. The second virtual array antenna is obtained by receiving radio waves transmitted from seven transmitting antenna elements Tx1-Tx3, Tx41, and Tx5-Tx7 by two rows of receiving antenna elements Rx11-Rx18, Rx21-Rx28, and performing predetermined signal processing on the received signals.

[0043] Here, the antenna aperture length of the second virtual array antenna of this embodiment is "13 dv", which is more than twice the antenna aperture length ("6 dv") in MISO. The second virtual array antenna of this embodiment has an antenna configuration in which the antenna elements are equally spaced. Note that MISO is an abbreviation for Multi Input Single Output.

[0044] The radar device 1 of this embodiment detects signals corresponding to targets using a first virtual array antenna having a large antenna aperture length, and detects information about the targets based on the detection results. The control unit 6 also detects signals corresponding to targets in the vertical direction V using a second virtual array antenna.

[0045] Next, the target detection process executed by the control unit 6 of the radar device 1 will be described with reference to Fig. 4. The process shown in Fig. 4 is executed by the control unit 6 periodically or irregularly when chirp signals are transmitted from the transmitting antenna group 3 at a predetermined transmission period.

[0046] 4, in step S100, the control unit 6 receives a reflected wave from a target at the receiving antenna group 4. This received signal is mixed with a local signal by the mixer of the receiving unit 5. After that, a desired frequency component is extracted by a low-pass filter, and the frequency component is provided from the receiving unit 5 to the control unit 6 as a beat signal.

[0047] Next, the control unit 6 performs distance FFT processing in step S110. The control unit 6 obtains the distance to the target by performing frequency analysis of the beat signal using FFT. Note that FFT is an abbreviation for Fast Fourier Transform.

[0048] Next, the control unit 6 performs a velocity FFT process in step S120. The control unit 6 performs an FFT for each beat frequency component to obtain a Doppler frequency, and obtains the relative velocity of the target based on the Doppler frequency.

[0049] Next, in step S130, the control unit 6 executes a horizontal direction detection process to detect the direction of the target in the horizontal direction U. In step S130, the control unit 6 estimates the direction of the target in the horizontal direction U by a first virtual array antenna (horizontal MIMO) obtained by MIMO in the horizontal direction U. Specifically, the control unit 6 estimates the direction of the target in the horizontal direction U based on the fact that the phase of the received signal received by the antenna elements constituting the first virtual array antenna differs depending on the angle of arrival of the reflected wave.

[0050] Next, the control unit 6 proceeds to step S140 and executes a vertical azimuth detection process to detect the azimuth of the target in the vertical direction V. In step S140, the control unit 6 estimates the azimuth of the target in the vertical direction V by an antenna configuration (vertical MIMO) obtained by MIMO in the vertical direction V. The control unit 6 estimates the azimuth of the target in the vertical direction V by using transmitting antenna elements Tx1-Tx3, Tx41, Tx5-Tx7 and receiving antenna elements Rx11-Rx18, Rx21-24 arranged in two rows in the horizontal direction U. Specifically, the control unit 6 detects the azimuth of the target in the vertical direction V based on the reception result at the second virtual array antenna of the reflected wave arriving from the azimuth of the target (first azimuth) detected in the horizontal azimuth detection process.

[0051] When the horizontal orientation detection process and the vertical orientation detection process are completed, the control unit 6 proceeds to step S150, where it identifies the distance to the target, the relative speed with respect to the target, and the orientation of the target obtained in the processes up to that point as information related to the target, and then exits this process.

[0052] The above is an explanation of the flow of the target detection process. Below, a description will be given of the results of a simulation of detection of the azimuths in the horizontal direction U and vertical direction V of the target, which is the target trg.

[0053] In this example, a simulation result in the case where there are three targets that serve as targets trg will be described with reference to Figs. 5 to 13. In the simulation of this example, as shown in Fig. 5, the first target trg1 is assumed to be present at approximately the center position (U=0, V=0) in the horizontal direction U and the vertical direction V. In addition, in this example, the second target trg2 is assumed to be present at a position shifted by "0.14" in the horizontal direction U from the first target trg1, and the third target trg3 is assumed to be present at a position shifted by "0.14" in the vertical direction V from the first target trg1. Note that "0.14" is converted to an angle of approximately "8°" as shown in the following formula F3.

[0054] sin(8° / 180°·π)≒0.14···(F3) Figure 6 shows the simulation results when estimating the azimuth of a target in the horizontal direction U by SIMO in the horizontal direction U (horizontal SIMO). As shown in Figure 6, the horizontal SIMO has a low resolution, so the peaks of the spectrum signals corresponding to the first and third targets trg1 and trg3 cannot be separated from the peak of the spectrum signal corresponding to the second target trg2.

[0055] On the other hand, Fig. 7 shows the simulation results when estimating the azimuth of a target in the horizontal direction U by MIMO in the horizontal direction U (horizontal MIMO). As shown in Fig. 7, with horizontal MIMO, the resolution is large, so the result was that the peaks of the spectrum signals corresponding to the first and third targets trg1 and trg3 and the peak of the spectrum signal corresponding to the second target trg2 can be appropriately separated.

[0056] Moreover, Fig. 8 shows the simulation results when the azimuth of a target in the vertical direction V is estimated by reproducing the spectral signal in the azimuth (U=-0.015 in this example) corresponding to the first and third targets trg1 and 3 detected in the azimuth estimation in the horizontal direction U. As shown in Fig. 8, the results show that the peaks of the spectral signal are detected at the positions corresponding to the first target trg1 and the third target trg3.

[0057] Moreover, Fig. 9 shows the simulation results when the azimuth of a target in the vertical direction V is estimated by reproducing the spectrum signal in the azimuth (U=0.16 in this example) corresponding to the second target trg2 detected in the azimuth estimation in the horizontal direction U. As shown in Fig. 9, the result was that a peak of the spectrum signal was detected at the position corresponding to the second target trg2.

[0058] In this way, by estimating the direction of a target in the horizontal direction U and the vertical direction V using horizontal MIMO and vertical MIMO, it is possible to properly detect the direction of a target in the horizontal direction U and the vertical direction V.

[0059] Here, Fig. 10 is a schematic diagram showing a transmitting antenna group TG and a receiving antenna group RG in a device that is a comparative example of this embodiment. The transmitting antenna group TG of the comparative example has four element rows, each consisting of two transmitting antenna elements arranged side by side in the horizontal direction U, arranged side by side in the vertical direction V, similar to the antenna configuration described in Patent Document 1. Specifically, a pair of transmitting antenna elements Tx11, Tx12, Tx21, Tx22, Tx31, Tx32, Tx41, and Tx42 arranged side by side in the horizontal direction U are arranged side by side in the vertical direction V. Moreover, the receiving antenna group RG of the comparative example has two element rows, each consisting of eight receiving antenna elements arranged side by side in the horizontal direction U, arranged side by side in the vertical direction V. Specifically, eight receiving antenna elements Rx11 to Rx18 and Rx21 to Rx28 arranged side by side in the horizontal direction U are arranged side by side in the vertical direction V.

[0060] Fig. 11 shows a simulation result when estimating the azimuth of a target in the horizontal direction U by MIMO in the horizontal direction U (horizontal MIMO) in the antenna configuration of the comparative example shown in Fig. 10. As shown in Fig. 11, with horizontal MIMO, the high resolution results in the ability to appropriately separate the peaks of the spectrum signals corresponding to the first and third targets trg1 and trg3 from the peak of the spectrum signal corresponding to the second target trg2.

[0061] FIG. 12 shows a simulation result when the azimuth of a target in the vertical direction V is estimated by reproducing a spectrum signal in the azimuth (U=-0.015 in this example) corresponding to the first and third targets trg1 and trg3 detected in the azimuth estimation in the horizontal direction U. In the antenna configuration of the comparative example, the number of transmitting antenna elements arranged in the vertical direction V is small, and the resolution is small. Therefore, as shown in FIG. 12, the peak of the spectrum signal corresponding to the first and third targets trg1 and trg3 and the peak of the spectrum signal corresponding to the second target trg2 cannot be separated. FIG. 13 shows a simulation result when the azimuth of a target in the vertical direction V is estimated by reproducing a spectrum signal in the azimuth (U=0.16 in this example) corresponding to the second target trg2 detected in the azimuth estimation in the horizontal direction U. As shown in FIG. 13, the peak of the spectrum signal is detected at the position corresponding to the second target trg2.

[0062] Thus, in the comparative example, the number of element rows each consisting of two transmitting antenna elements arranged side by side in the horizontal direction U is set to be the same as the number of transmitting antenna elements arranged side by side in the vertical direction V (four in the comparative example). In such an antenna configuration, the number of transmitting antenna elements arranged side by side in the horizontal direction U increases. In this case, the number of transmitting antenna elements arranged side by side in the vertical direction V is limited, thereby decreasing the detection accuracy of information related to the target in the vertical direction V.

[0063] Here, in order to improve the detection accuracy of information related to targets in the vertical direction V, it is possible to increase the number of transmitting antenna elements arranged in the vertical direction V, but this would result in a significant increase in the number of parts. Also, the power efficiency of millimeter wave transmitting amplifiers is generally poor, and operating a large number of them increases the power consumption of the MMIC and causes heat generation problems, so the number of transmitting antenna elements may be limited.

[0064] In contrast to these, in the radar device 1 of this embodiment, the transmitting antenna elements are arranged so that the number of transmitting antenna elements Tx1 to Tx3, Tx41, and Tx5 to Tx7 constituting the “second element array” in the transmitting antenna group 3 is greater than the number of the “first element array”.

[0065] In such an antenna configuration, the number of transmitting antenna elements arranged in the horizontal direction U is reduced, while the number of transmitting antenna elements arranged in the vertical direction V is increased, thereby ensuring the antenna aperture length in the vertical direction V and improving the resolution in the vertical direction V.

[0066] Therefore, the radar device 1 of this embodiment can appropriately detect information about targets in both the horizontal direction U and the vertical direction V intersecting the horizontal direction U while suppressing an increase in the number of transmitting antenna elements.

[0067] Moreover, the radar device 1 of this embodiment has the following features. (1) The first detection unit 61 of the control unit 6 detects the azimuth of the target in the horizontal direction U based on the reception result of the reflected wave at the first virtual array antenna. When the azimuth of the target detected by this first detection unit 61 is defined as the first azimuth, the second detection unit 62 detects the azimuth of the target in the vertical direction V based on the reception result of the reflected wave arriving from the first azimuth at the second virtual array antenna. This makes it possible to appropriately detect the azimuth of the target in different directions, such as the horizontal direction U and the vertical direction V.

[0068] (2) The radar device 1 is mounted on a vehicle. The "first direction" is the horizontal direction U corresponding to the width direction of the vehicle, and the "second direction" is the vertical direction V corresponding to the height direction of the vehicle. This makes it possible to appropriately detect information about targets in both the horizontal direction U and the vertical direction V while suppressing an increase in the number of transmitting antenna elements of the radar device 1 mounted on the vehicle.

[0069] Second embodiment Next, a second embodiment will be described with reference to Fig. 14. In this embodiment, differences from the first embodiment will be mainly described.

[0070] 14, in order to narrow the beam in the vertical direction V, the transmitting antenna elements Tx1-Tx3, Tx41, Tx42, and Tx5-Tx7 of this embodiment have a dimension Ltv in the vertical direction V that is longer than the dimension Lth in the horizontal direction U. Also, the receiving antenna elements Rx11-R18, and Rx21-Rx28 of this embodiment have a rectangular shape similar to the transmitting antenna elements Tx1-Tx3, Tx41, Tx42, and Tx5-Tx7. That is, the receiving antenna elements Rx11-R18, and Rx21-Rx28 have a dimension Lrv in the vertical direction V that is longer than the dimension Lrh in the horizontal direction U.

[0071] In the transmitting antenna group 3, the transmitting antenna elements Tx1 to Tx3, Tx41, and Tx5 to Tx7 constituting a "second element array" are arranged offset in the horizontal direction U so as not to overlap one another in the vertical direction V. Specifically, in the transmitting antenna group 3, the transmitting antenna elements Tx1 to Tx3, and Tx41 are arranged offset in the horizontal direction U at a horizontal reference distance dh. In addition, in the transmitting antenna group 3, the transmitting antenna elements Tx42, and Tx5 to Tx7 are arranged offset in the horizontal direction U at a horizontal reference distance dh.

[0072] In the receiving antenna group 4, receiving element rows Rx1, Rx2 are arranged side by side in the horizontal direction U, facing each other with a gap in between in the vertical direction V. In the transmitting antenna group 3, some of the transmitting antenna elements Tx1-Tx3, Tx41, Tx5-Tx7 constituting a "second element row" are arranged between the receiving element rows Rx1, Rx2 arranged in the vertical direction V. Specifically, the transmitting antenna elements Tx1-Tx3, Tx5-Tx7 are arranged between the receiving element rows Rx1, Rx2 arranged in the vertical direction V.

[0073] The rest is the same as in the first embodiment. The radar device 1 of this embodiment can obtain the same effects as in the first embodiment, which are achieved by a configuration common to the first embodiment or an equivalent configuration.

[0074] Moreover, the radar device 1 of this embodiment has the following features. (1) In the transmitting antenna group 3, the transmitting antenna elements Tx1 to Tx3, Tx41, and Tx5 to Tx7 constituting the "second element row" are arranged with an offset in the horizontal direction U. This prevents interference between the transmitting antenna elements in the vertical direction V, thereby suppressing an increase in the size in the vertical direction V that would be otherwise caused by an increase in the number of transmitting antenna elements arranged side by side in the vertical direction V. Note that when the rectangular antenna element of the present proposal is applied to the antenna configuration shown in the comparative example of Fig. 10, for example, adjacent transmitting antenna elements Tx11, Tx21 and transmitting antenna elements Tx12, Tx22 interfere with each other in the vertical direction V. In order to avoid this interference, for example, it is possible to offset the transmitting antenna elements Tx21, Tx22 in the horizontal direction U, but since the interval between the transmitting antenna elements Tx21, Tx22 needs to be set to "8dh", the size in the horizontal direction U increases by the amount of offset.

[0075] (2) In addition, in the transmitting antenna group 3, some of the transmitting antenna elements Tx1 to Tx3, Tx41, and Tx5 to Tx7 constituting the "second element array" are arranged between the receiving element arrays Rx1, Rx2 arranged in the vertical direction V. In this way, by arranging the transmitting antenna elements in the space between the receiving element arrays Rx1, Rx2 facing each other in the vertical direction V, it is possible to suppress an increase in the physical size in the horizontal direction U.

[0076] (Modification of the second embodiment) In the transmitting antenna group 3 of the second embodiment, the transmitting antenna elements Tx1 to Tx3, Tx41, and Tx5 to Tx7 constituting the "second element array" are arranged offset in the horizontal direction U so as not to overlap in the vertical direction V, but are not limited to this. The transmitting antenna group 3 may be arranged such that the transmitting antenna elements Tx1 to Tx3, Tx41, and Tx5 to Tx7 constituting the "second element array" partially overlap in the vertical direction V. Furthermore, the number of transmitting antenna elements in the transmitting antenna group 3 that are offset in the horizontal direction U may be different from that described above.

[0077] In addition, the receiving antenna group 4 in the second embodiment is arranged side by side along the horizontal direction U so as to overlap each other in the horizontal direction U, but may be arranged offset in the vertical direction V so that some of them do not overlap each other in the horizontal direction U.

[0078] (Other embodiments) Representative embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments and can be modified in various ways, for example, as described below.

[0079] In the above-described embodiment, a specific example of the antenna configuration of the radar device 1 is given, but the antenna configuration of the radar device 1 is not limited to the above-described one, and the antenna configuration may be different from the above-described one.

[0080] The number of transmitting antenna elements constituting the transmitting antenna group 3 is merely an example, and may be different from the above-mentioned number. The same applies to the number of receiving antenna elements constituting the receiving antenna group 4.

[0081] The radar device 1 may have an antenna configuration in which the arrangement of the transmitting antenna elements Tx1 to Tx3, Tx41, Tx42, and Tx5 to Tx7 and the receiving antenna elements Rx11 to Rx18, and Rx21 to Rx28 is reversed. In the above-mentioned embodiment, the two different directions are the horizontal direction U and the vertical direction V, but they may be different directions.

[0082] As in the above embodiment, the multiple receiving antenna elements Rx11-Rx18, Rx21-Rx28 are preferably arranged at equal intervals with a reference interval that is 1 times the horizontal reference distance dh, but are not limited to this. The multiple receiving antenna elements Rx11-Rx18, Rx21-Rx28 may be arranged, for example, such that at least some of them are unevenly spaced. In addition, the transmitting antenna elements Tx41, Tx42 are preferably arranged at intervals that are greater than the antenna aperture length of the receiving antenna elements Rx11-Rx18, Rx21-Rx28 by the horizontal reference distance dh, but this is not necessarily required.

[0083] In the above embodiment, an example has been described in which the radar device 1 of the present disclosure is applied to a target detection device that is mounted on a vehicle and detects various targets present around the vehicle, but the application of the radar device 1 is not limited to this. The radar device 1 can also be applied to, for example, moving objects other than vehicles and stationary devices.

[0084] In the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where it is particularly expressly stated that they are essential or where they are clearly considered to be essential in principle.

[0085] In the above-described embodiments, when numerical values ​​such as the number, values, amounts, ranges, etc. of components of the embodiments are mentioned, they are not limited to the specific numbers unless it is specifically stated as required or unless it is clearly limited to a specific number in principle.

[0086] In the above-described embodiments, when referring to the shapes, positional relationships, etc. of components, etc., there is no limitation to those shapes, positional relationships, etc., unless specifically stated or in principle limited to a specific shape, positional relationship, etc.

[0087] The control unit and the method of the present disclosure may be implemented in a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. The control unit and the method of the present disclosure may be implemented in a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. The control unit and the method of the present disclosure may be implemented in one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. The computer program may also be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer. [Explanation of symbols]

[0088] 1. Radar equipment 3 Transmitting antennas 4 Receiving antennas 61 First detection unit 62 Second detection unit

Claims

1. A radar device that detects targets using radio waves, A transmitting antenna group (3) including a plurality of transmitting antenna elements; A receiving antenna group (4) including a plurality of receiving antenna elements; a first detection unit (61) that detects information about the target in a predetermined first direction based on a reception result of a reflected wave corresponding to a transmission wave from the transmitting antenna group at a first virtual array antenna using a first element row consisting of a plurality of the transmitting antenna elements arranged in the first direction and a plurality of the receiving antenna elements arranged in the first direction; a second detection unit (62) that detects information about the target in the second direction based on a reception result of the reflected wave at a second element row including a plurality of the transmitting antenna elements arranged in a second direction intersecting the first direction and a second virtual array antenna using a plurality of the receiving antenna elements arranged in the second direction, a radar device, wherein the transmitting antenna group includes a plurality of transmitting antenna elements arranged such that the number of transmitting antenna elements constituting the second element row is greater than the number of transmitting antenna elements constituting the first element row.

2. The plurality of transmitting antenna elements have a dimension in the second direction longer than a dimension in the first direction, The radar device according to claim 1 , wherein the transmitting antenna group includes at least some of the transmitting antenna elements constituting the second element array that are arranged to be offset in the first direction.

3. The receiving antenna group includes receiving element rows arranged side by side in the first direction and arranged opposite to each other at an interval in the second direction, The radar device according to claim 2 , wherein at least some of the transmitting antenna elements constituting the second element array of the transmitting antenna group are disposed between the receiving element arrays aligned in the second direction.

4. The first detection unit detects an azimuth of the target in the first direction based on a reception result of the reflected wave at the first virtual array antenna, 3. The radar device according to claim 1, wherein when the azimuth of the target detected by the first detection unit is a first azimuth, the second detection unit detects the azimuth of the target in the second direction based on a reception result of the reflected wave arriving from the first azimuth at the second virtual array antenna.

5. It is mounted on a vehicle, the first direction is a horizontal direction corresponding to a width direction of the vehicle, The radar device according to claim 1 , wherein the second direction is a vertical direction corresponding to a height direction of the vehicle.

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