Radar device

Abstract

To provide a radar device capable of correcting at least one of the phase difference and amplitude difference of a signal generated between a plurality of transmitting / receiving circuits to which a plurality of antenna elements are connected in a distributed manner.SOLUTION: A radar device 1 includes a plurality of transmitting / receiving circuits 20 and 30 to which a plurality of antenna elements are connected in a distributed manner. The radar device 1 includes a correction processing portion 55 that corrects the phase difference and amplitude difference of a signal generated between a first transmitting / receiving circuit 20 and a second transmitting / receiving circuit 30 as correction target components. The radar device 1 is configured such that a first virtual antenna using an antenna element connected to the first transmitting / receiving circuit 20 and a second virtual antenna using an antenna element connected to each of the transmitting / receiving circuits 20 and 30 overlap each other when one of the virtual antennas is slid. The correction processing portion 55 corrects the correction target component of a correction target circuit on the basis of a comparison with a detection result of a signal corresponding to a target based on a reception signal in a signal received by each virtual antenna.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a radar device that detects targets using radio waves. [Background technology]

[0002] Conventionally, radar devices are known in which a plurality of transmitting antenna elements and a plurality of receiving antenna elements are distributed and connected to a plurality of receiving ICs in order to support multi-channelization (see, for example, Patent Document 1). In Patent Document 1, a plurality of transmitting antenna elements are arranged at a predetermined interval so that the positions of the receiving antenna elements in different receiving ICs virtually overlap, and the results of receiving signals at the virtually overlapping receiving antenna elements are compared to compensate for the phase difference occurring between the receiving ICs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-60732 A Summary of the Invention [Problem to be solved by the invention]

[0004] As in Patent Document 1, when an antenna configuration is adopted in which the positions of receiving antenna elements in different receiving ICs are virtually overlapped, it becomes possible to compensate for the phase difference occurring between the receiving ICs, but the antenna aperture length, etc. is limited due to the redundancy of the antenna elements. This is also true when compensating for the amplitude difference occurring between the receiving ICs.

[0005] The present disclosure provides a radar device that can correct at least one of a phase difference and an amplitude difference of signals occurring between a plurality of transmission / reception circuits as a correction target component, without making antenna elements redundant. [Means for solving the problem]

[0006] The invention described in claim 1 is A radar device that detects targets using radio waves, A transmitting antenna group (Tx) including a plurality of transmitting antenna elements; A receiving antenna group (Rx) including a plurality of receiving antenna elements; a plurality of transmitting / receiving circuits (20, 30, 40, 60) to which a plurality of transmitting antenna elements and a plurality of receiving antenna elements are connected; a correction processing unit (55) that uses a part of the plurality of transmission / reception circuits as a reference circuit and the other transmission / reception circuits excluding the reference circuit as correction target circuits, and corrects at least one of a phase difference and an amplitude difference of a signal occurring between the reference circuit and the correction target circuit as a correction target component; A virtual antenna using both the transmitting antenna element and the receiving antenna element connected to the reference circuit is defined as a first virtual antenna, and a virtual antenna using one of the transmitting antenna element and the receiving antenna element connected to the reference circuit and the other of the transmitting antenna element and the receiving antenna element connected to the correction target circuit is defined as a second virtual antenna. the first virtual antenna has an antenna configuration in which the first virtual antenna overlaps with the second virtual antenna when the first virtual antenna is virtually slid in a predetermined direction; The correction processing unit corrects the correction target component of the correction target circuit based on a comparison between a detection result of a signal corresponding to the target based on the received signal at the first virtual antenna and a detection result of a signal corresponding to the target based on the received signal at the second virtual antenna.

[0007] The radar device of the present disclosure has an antenna configuration in which the first virtual antenna and the second virtual antenna are positioned differently, but overlap when virtually slid in a predetermined direction. In such a configuration, if there is no phase difference or amplitude difference between the signals of the multiple transmission / reception circuits, the signals corresponding to the target based on the signals received by the first virtual antenna and the second virtual antenna will be substantially the same. However, if there is a phase difference or amplitude difference between the signals of the multiple transmission / reception circuits, the signals corresponding to the target based on the signals received by the first virtual antenna and the second virtual antenna will be different due to the influence of the phase difference and amplitude difference in the multiple transmission / reception circuits.

[0008] In consideration of such characteristics, the radar device of the present disclosure is adapted to correct the phase difference and amplitude difference in the multiple transmission / reception circuits by comparing the target detection result based on the received signal at the first virtual antenna with the target detection result based on the received signal at the second virtual antenna. This configuration for correcting the phase difference and amplitude difference in the multiple transmission / reception circuits does not require redundant antenna elements.

[0009] Therefore, according to the radar device of the present disclosure, at least one of the phase error and the amplitude error of the signal occurring between a plurality of transmission / reception circuits can be corrected as a correction target component without making the antenna elements redundant.

[0010] Note that 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]

[0011] [Figure 1] 1 is a schematic configuration diagram of a radar device according to a first embodiment. [Diagram 2] FIG. 2 is an explanatory diagram for explaining an antenna configuration of the radar device according to the first embodiment. [Diagram 3] 3 is an explanatory diagram for explaining a virtual antenna based on the antenna configuration shown in FIG. 2. [Figure 4] FIG. 2 is an explanatory diagram for explaining received signals etc. received by each virtual antenna. [Diagram 5] 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. [Figure 6] 10 is an explanatory diagram for explaining an example of distance information obtained by distance FFT executed by a control unit. FIG. [Figure 7] 10 is an explanatory diagram for explaining an example of velocity information obtained by a velocity FFT executed by a control unit. FIG. [Figure 8]10 is an explanatory diagram for explaining a method of selecting a comparison signal for detecting a correction target component. FIG. [Figure 9] FIG. 11 is an explanatory diagram for explaining a modified example of the first embodiment. [Figure 10] FIG. 11 is an explanatory diagram for explaining an antenna configuration of a radar device according to a second embodiment. [Figure 11] 10 is a flowchart showing a flow of a process for selecting a comparison signal for detecting a correction target component, which is executed by a control unit. [Figure 12] FIG. 11 is an explanatory diagram for explaining a comparison signal selection method. [Figure 13] FIG. 11 is a partial configuration diagram showing a part of a radar device according to a third embodiment. [Figure 14] FIG. 11 is an explanatory diagram for explaining an antenna configuration of a radar device according to a third embodiment. [Figure 15] 15 is an explanatory diagram for explaining a MIMO antenna in the horizontal direction based on the antenna configuration shown in FIG. 14. [Figure 16] FIG. 11 is a partial configuration diagram showing a part of a radar device according to a fourth embodiment. [Figure 17] FIG. 13 is an explanatory diagram for explaining an antenna configuration of a radar device according to a fourth embodiment. [Figure 18] 18 is an explanatory diagram for explaining a first MIMO antenna and a second MIMO antenna based on the antenna configuration of FIG. 17. [Figure 19] 18 is an explanatory diagram for explaining a third MIMO antenna and a fourth MIMO antenna based on the antenna configuration of FIG. 17. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 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.

[0013] (First embodiment) The present embodiment will be described with reference to Fig. 1 to Fig. 8. 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.

[0014] 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.

[0015] 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.

[0016] 1, the radar device 1 includes a sensor housing (not shown), multiple radar units RU1 and RU2, and a control unit 50. In this embodiment, the radar device 1 includes a first radar unit RU1 and a second radar unit RU2, but the radar device 1 may include three or more radar units RU.

[0017] The sensor housing is a member that constitutes the outer shell of the radar device 1. The sensor housing includes a first radar unit RU1, a second radar unit RU2, and a control unit 50. Note that the control unit 50 may be provided outside the sensor housing.

[0018] The first radar unit RU1 includes a first transmitter 21, an actual transmitting antenna element Tx1, a plurality of actual receiving antenna elements Rx11-Rx14, and a first receiver 22. The first transmitter 21 and the first receiver 22 configure a first transmission / reception circuit 20. The first transmission / reception circuit 20 is configured to be mounted on a semiconductor chip such as an MMIC. Note that MMIC is an abbreviation for Monolithic Microwave Integrated Circuit.

[0019] The second radar unit RU2 includes a second transmitter 31, an actual transmitting antenna element Tx2, a plurality of actual receiving antenna elements Rx21-Rx24, and a second receiver 32. The second transmitter 31 and the second receiver 32 configure a second transmission / reception circuit 30. The second transmission / reception circuit 30 is configured to be mounted on a semiconductor chip such as an MMIC.

[0020] In this embodiment, the transmitting antenna element Tx1 of the first radar unit RU1 and the transmitting antenna element Tx2 of the second radar unit RU2 constitute a "transmitting antenna group Tx." Similarly, the receiving antenna elements Rx11-Rx14 of the first radar unit RU1 and the receiving antenna elements Rx21-Rx24 of the second radar unit RU2 constitute a "receiving antenna group Rx." Details of the "transmitting antenna group Tx" and the "receiving antenna group Rx" will be described later.

[0021] The first transmitter 21 of the first radar unit RU1 generates a signal to be transmitted from the transmitting antenna element Tx1 and transmits the signal to the transmitting antenna element Tx1. Specifically, the first transmitter 21 includes a local oscillator 211 that generates a local signal, and transmits the local signal generated by the local oscillator 211 to the first receiver 22. The first transmitter 21 also generates a chirp signal whose frequency changes continuously, and provides the generated chirp signal to the transmitting antenna element Tx1. The transmitting antenna element Tx1 then transmits radio waves corresponding to the chirp signal provided from the first transmitter 21 toward the front of the vehicle.

[0022] Furthermore, the first receiving unit 22 generates a beat signal based on the reception signals received by the receiving antenna elements Rx11 to Rx14 and the local signal transmitted from the first transmitting unit 21, samples the beat signal, and provides it to the control unit 50. Although not shown, the first receiving unit 22 is configured to include a mixer, an amplifier, an AD converter, etc.

[0023] The second transmitting unit 31 of the second radar unit RU2 generates a signal to be transmitted from the transmitting antenna element Tx2 and transmits the signal to the transmitting antenna element Tx2. Specifically, the second transmitting unit 31 includes a local oscillator 311 that generates a local signal, and transmits the local signal generated by the local oscillator 311 to the second receiving unit 32. The second transmitting unit 31 also generates a chirp signal whose frequency changes continuously, and provides the generated chirp signal to the transmitting antenna element Tx2. The transmitting antenna element Tx2 then transmits radio waves corresponding to the chirp signal provided from the second transmitting unit 31 toward the front of the vehicle.

[0024] Moreover, the second receiving unit 32 generates a beat signal based on the reception signals received by the receiving antenna elements Rx21 to Rx24 and the local signal transmitted from the second transmitting unit 31, samples the beat signal, and provides it to the control unit 50. Although not shown, the second receiving unit 32 is configured to include a mixer, an amplifier, an AD converter, etc.

[0025] Here, the transmitting antenna group Tx and the receiving antenna group Rx of this example will be described with reference to Fig. 2. As shown in Fig. 2, the transmitting antenna group Tx of this example has two actual transmitting antenna elements Tx1 and Tx2. Also, the receiving antenna group Rx of this example has eight actual receiving antenna elements Rx11 to Rx14 and Rx21 to Rx24.

[0026] The two transmitting antenna elements Tx1, Tx2 constituting the transmitting antenna group Tx are arranged side by side in a horizontal direction U when the radar device 1 is mounted on a vehicle. In this embodiment, the horizontal direction U corresponding to the width direction of the vehicle corresponds to the "predetermined direction".

[0027] In the transmitting antenna group Tx, two transmitting antenna elements Tx1 and Tx2 are arranged along the horizontal direction U at a predetermined reference interval. The transmitting antenna elements Tx1 and Tx2 arranged in the horizontal direction U are arranged at an interval of "5dh", which is five times the predetermined horizontal reference distance "dh" (reference interval = 5dh in this example). The interval between the transmitting antenna elements Tx1 and Tx2 may be a strict 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 Rx14 and Rx21 to Rx24 arranged in the horizontal direction U.

[0028] The horizontal reference distance "dh" 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·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.

[0029] 1 / sin(θfov / 180 π) 2 <dh ···(F1) The receiving antenna group Rx receives radio waves and the like transmitted from the transmitting antenna group Tx and reflected by a target. In this example, the receiving antenna group Rx is composed of eight actually existing receiving antenna elements Rx11 to Rx14, Rx21 to Rx24. The eight receiving antenna elements Rx11 to Rx14, Rx21 to Rx24 constituting the receiving antenna group Rx are arranged in a row in the horizontal direction U when the radar device 1 is mounted on a vehicle. The eight receiving antenna elements Rx11 to Rx14, Rx21 to Rx24 are arranged at equal intervals of "1dh", which is one time the horizontal reference distance "dh".

[0030] 3, the four receiving antenna elements Rx11-Rx14 connected to the first transmitting / receiving circuit 20 are spaced apart at intervals smaller than the spacing between the transmitting antenna elements Tx1 and Tx2 (5dh in this example). Although not shown, the four receiving antenna elements Rx21-Rx24 connected to the second transmitting / receiving circuit 20 are also spaced apart at intervals smaller than the spacing between the transmitting antenna elements Tx1 and Tx2 (5dh in this example).

[0031] In such an antenna configuration, for example, a virtual antenna in which the receiving antenna elements Rx11 to Rx14 receive a reflected wave corresponding to a transmission wave from the transmitting antenna element Tx1 is a first SIMO antenna shown on the left side of the lower part of Fig. 3. Also, a virtual antenna in which the receiving antenna elements Rx11 to Rx14 receive a reflected wave corresponding to a transmission wave from the transmitting antenna element Tx2 is a second SIMO antenna shown on the right side of the lower part of Fig. 3. Note that "SIMO" is an abbreviation for Single Input Multi Output. In this embodiment, one of the first SIMO antenna and the second SIMO antenna corresponds to a "first virtual antenna", and the other corresponds to a "second virtual antenna".

[0032] A virtual antenna (MIMO antenna) including the first SIMO antenna and the second SIMO antenna is configured such that the antenna elements constituting the first SIMO antenna do not overlap with the antenna elements constituting the second SIMO antenna. Note that a MIMO antenna is an array antenna that is virtually generated based on the reception results when radio waves transmitted from multiple antenna elements are received by multiple antenna elements. Also, "MIMO" is an abbreviation for Multi Input Multi Output.

[0033] On the other hand, the first SIMO antenna and the second SIMO antenna use the receiving antenna elements Rx11 to Rx14 connected to the first transmitting / receiving circuit 20 as a common antenna element.

[0034] In addition, when one SIMO antenna is slid, it overlaps with the other SIMO antenna. In other words, when the first SIMO antenna is slid in the horizontal direction U, it overlaps with the second SIMO antenna. This makes the target detection accuracy of the first SIMO antenna and the second SIMO antenna equivalent.

[0035] In the radar device 1 configured in this manner, if there is no phase difference or amplitude difference in the signals between the multiple transmission / reception circuits 20, 30, the signals corresponding to the target based on the received signals of the first SIMO antenna and the second SIMO antenna will be approximately the same.

[0036] However, if there is a phase difference and amplitude difference between signals between the multiple transmission / reception circuits 20, 30, the signals corresponding to the target based on the received signals of the first SIMO antenna and the second SIMO antenna will be different due to the influence of the phase difference and amplitude difference.

[0037] In consideration of such characteristics, the radar device 1 is configured such that the control unit 50 compares the target detection results based on the signals received by each SIMO antenna, and corrects the phase difference and amplitude difference in each of the transmission / reception circuits 20, 30.

[0038] The control unit 50 is an electronic control device mainly composed of a microcomputer having 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.

[0039] The first radar unit RU1 and the second radar unit RU2 are connected to the control unit 50. The control unit 50 detects a signal corresponding to a target based on radio waves received by the receiving antenna group Rx after a reflected wave corresponding to a radio wave transmitted from the transmitting antenna group Tx.

[0040] The control unit 50 detects a target based on a reception result at the receiving antenna elements Rx11-Rx14, Rx21-Rx24 of a reflected wave corresponding to a transmission wave transmitted from at least one of the transmitting antenna elements Tx1, Tx2. In this embodiment, the software and hardware for detecting a target in the control unit 50 constitute a "target detection unit 51."

[0041] The target detection unit 51 of this embodiment obtains a distance spectrum as distance information having a correlation with the distance to the target based on the reception results of the transmission waves from the transmitting antenna elements Tx1 and Tx2 at the receiving antenna elements Rx11-Rx14 and Rx21-Rx24. In this embodiment, the software and hardware of the target detection unit 51 that obtains the distance information constitutes a "distance calculation unit 52." The distance spectrum is a frequency spectrum that has a correlation with the distance to the target.

[0042] The target detection unit 51 obtains a speed spectrum as speed information having a correlation with the relative speed with respect to the target based on the reception results of the transmission waves from the transmitting antenna elements Tx1 and Tx2 at the receiving antenna elements Rx11-Rx14 and Rx21-Rx24. In this embodiment, the software and hardware of the target detection unit 51 that obtains the speed information constitutes a "speed calculation unit 53." The speed spectrum is a frequency spectrum that has a correlation with the relative speed with respect to the target.

[0043] Furthermore, the target detection unit 51 estimates the azimuth of the target based on the reception results of the transmission waves from the transmitting antenna elements Tx1 and Tx2 at the receiving antenna elements Rx11-Rx14 and Rx21-Rx24. In this embodiment, the software and hardware of the target detection unit 51 that estimates the azimuth of the target constitutes an "azimuth estimation unit 54."

[0044] Here, the radar device 1 of this embodiment generates a chirp signal and a beat signal based on local signals generated by local oscillators 211, 311 provided in the first transmission / reception circuit 20 and the second transmission / reception circuit 30, respectively. For this reason, a phase shift (i.e., a phase difference) may occur between the first transmission / reception circuit 20 and the second transmission / reception circuit 30 due to the use of different local oscillators 211, 311.

[0045] Furthermore, the radar device 1 generates a chirp signal and a beat signal using equipment such as an amplifier and an AD converter provided in each of the first transmission / reception circuit 20 and the second transmission / reception circuit 30. For this reason, an amplitude deviation (i.e., an amplitude difference) may occur between the first transmission / reception circuit 20 and the second transmission / reception circuit 30 due to the use of different equipment. In the radar device 1, a large phase difference and amplitude difference between the first transmission / reception circuit 20 and the second transmission / reception circuit 30 is not preferable because it leads to a decrease in the detection accuracy of the target.

[0046] Taking these factors into consideration, the radar device 1 designates some of the transceiver circuits as "reference sections" and the other transceiver circuits excluding the "reference sections" as "circuits to be corrected," and corrects either the phase difference or the amplitude difference in the "circuits to be corrected" relative to the "reference sections" as the component to be corrected.

[0047] Specifically, the control unit 50 regards the first transmission / reception circuit 20 as a reference unit and the second transmission / reception circuit 30 as a correction target circuit, and corrects both the phase difference and the amplitude difference occurring between the first transmission / reception circuit 20 and the second transmission / reception circuit 30 as correction target components. In this embodiment, software and hardware in the control unit 50 that corrects the phase difference and the amplitude difference occurring between the transmission / reception circuits 20, 30 constitute a "correction processing unit 55."

[0048] As described above, the control unit 50 of this embodiment compares the target detection result based on the received signal at the first SIMO antenna with the target detection result based on the received signal at the second SIMO antenna, and corrects the phase difference and amplitude difference in each of the transmission / reception circuits 20, 30.

[0049] Specifically, the control unit 50 obtains the phase difference and amplitude difference in each of the transmission / reception circuits 20, 30 as correction target components from the target detection result based on the reception signal at each SIMO antenna. Next, the control unit 50 calculates a correction coefficient from the correction target components for matching the phase and amplitude on the second transmission / reception circuit 30 side with the phase and amplitude on the first transmission / reception circuit 20 side. Then, when detecting a target, the control unit 50 corrects the phase and amplitude of the reception signals of the receiving antenna elements Rx21-Rx24 on the second transmission / reception circuit 30 side using the correction coefficient.

[0050] Here, the received signal x of the receiving antenna elements Rx11 to Rx14 of the transmitted wave from the transmitting antenna element Tx1 is 11 ~x 14 The received signal vector X1 representing the above is expressed by the formula F2 in Fig. 4. In the formula F2, "θ" represents the azimuth, and "s" represents the signal component corresponding to the target.

[0051] The received signal x at the receiving antenna elements Rx11 to Rx14 of the transmitted wave from the transmitting antenna element Tx2 11 ~x 14The received signal vector X2 indicating the above is shown in formula F3 in Fig. 4. In formula F3, "θ" indicates the azimuth, "s" indicates the signal component corresponding to the target, "γ" indicates the phase difference between the transmission / reception circuits 20 and 30, and "A" indicates the amplitude difference between the transmission / reception circuits 20 and 30.

[0052] Moreover, the array vector A1 determined from the azimuth of the target and the positional relationship between the transmitting antenna element Tx1 and the receiving antenna elements Rx11-Rx14 is shown in formula F4 in Fig. 4. The array vector A2 determined from the azimuth of the target and the positional relationship between the transmitting antenna element Tx2 and the receiving antenna elements Rx11-Rx14 is shown in formula F5 in Fig. 4. Note that "T" in formulas F4 and F5 is a symbol indicating transposition.

[0053] The regenerated signal s1 obtained by regenerating the signal corresponding to the target received by the first SIMO antenna using digital beamforming is shown in formula F6 in Fig. 4. The regenerated signal s1 is obtained by multiplying the received signal vector X1 and the array vector A1. Hereinafter, digital beamforming may be referred to as DBF.

[0054] Moreover, the regenerated signal s2 obtained by regenerating the signal corresponding to the target received by the second SIMO antenna using DBF is expressed by formula F7 in Fig. 4. The regenerated signal s2 is obtained by multiplying the received signal vector X2 by the array vector A2.

[0055] 4, one of the reproduced signals s1, s2 contains a phase difference and an amplitude difference in the multiple transmitting / receiving circuits 20, 30. Therefore, by comparing the reproduced signals s1, s2 with each other, as shown in formula F8, "γ" indicating the phase difference and "A" indicating the amplitude difference between the transmitting / receiving circuits 20, 30 are extracted.

[0056] In this way, by comparing the regenerated signals s1 and s2 obtained by regenerating the signals corresponding to the target received by each SIMO antenna using DBF, it is possible to obtain “γ”, which indicates the phase difference, and “A”, which indicates the amplitude difference.

[0057] Here, when a target does not exist within the viewing angle of the radar device 1, the influence of noise becomes large. Therefore, when a target exists within the target detectable range of the radar device 1, the control unit 50 of this embodiment compares the reproduced signals s1 and s2, and corrects the correction target component of the correction target circuit based on the comparison result. In other words, the control unit 50 uses the signal received by each of the receiving antenna elements Rx11 and Rx14 that corresponds to the target as a comparison signal, and corrects the correction target component of the correction target circuit by comparing the reproduction result obtained by reproducing the comparison signal by DBF.

[0058] Such correction of the correction target components is performed every time a target detection process for detecting a target is executed by the radar device 1. The target detection process executed by the control unit 50 of the radar device 1 will be described below with reference to Fig. 5. The process shown in Fig. 5 is executed by the control unit 50 periodically or irregularly when a chirp signal is transmitted from the transmitting antenna group Tx at a predetermined transmission period.

[0059] 6, in step S100, the control unit 50 receives reflected waves from a target using the receiving antenna group Rx. The received signals are mixed with local signals in the mixers of the receiving units 22 and 32 of the radar units RU1 and RU2. Then, desired frequency components are extracted by a low-pass filter, and the frequency components are provided to the control unit 50 from the receiving units 22 and 32 as beat signals.

[0060] Next, the control unit 50 performs distance FFT processing in step S110. The control unit 50 performs frequency analysis of the beat signal using FFT to obtain a distance spectrum as distance information having a correlation with the distance to the target. The control unit 50 analyzes the signals received by each of the receiving antenna elements Rx11-Rx14 and Rx21-Rx24, and obtains a distance spectrum for each of the receiving antenna elements Rx11-Rx14 and Rx21-Rx24, for example, as shown in Fig. 6. Note that FFT is an abbreviation for Fast Fourier Transform.

[0061] Next, the control unit 50 performs a velocity FFT process in step S120. The control unit 50 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. The control unit 50 analyzes the signals received by each of the receiving antenna elements Rx11-Rx14 and Rx21-Rx24, and obtains a velocity spectrum as velocity information for each of the receiving antenna elements Rx11-Rx14 and Rx21-Rx24, for example, as shown in FIG.

[0062] Next, in step S130, the control unit 50 determines whether or not a target has been detected. For example, the control unit 50 determines that a target has been detected if a peak indicating the distance to the target is detected when performing FFT on the beat signal, and determines that a target has not been detected if a peak indicating the distance to the target is not detected.

[0063] If a target is not detected, the control unit 50 skips the subsequent processes and exits the target detection process. If a target is detected, the control unit 50 proceeds to step S140 and continues the target detection process.

[0064] In step S140, the control unit 50 selects, from among the signals received by the first SIMO antenna and the second SIMO antenna, one that corresponds to the target as a comparison signal.

[0065] Here, the propagation of radio waves (i.e., the received power) attenuates inversely proportional to the fourth power of the distance. Therefore, the signal corresponding to a target that is closer has a higher S / N ratio and is less susceptible to the effects of noise. In addition, for example, when the transmitting antenna elements Tx1 and Tx2 are multiplexed and transmitted by a time division multiplexing method, the target may move due to different transmission timings of radio waves, and a phase change may be added due to the difference in distance to the target.

[0066] Taking these factors into consideration, the control unit 50 of this embodiment selects as a comparison signal, from among signals indicating a target, one that indicates that the distance to the target is less than a reference distance and that the relative speed to the target is less than a reference speed.

[0067] For example, when there are three targets Trg1 to Trg3 with different distances and speeds as shown in FIG. 8, the control unit 50 selects the signal indicating the target Trg1 that is close in distance and has a small relative speed as the comparison signal.

[0068] The control unit 50 of this embodiment selects a comparison signal using distance information and speed information based on a reception signal received on the side of the first transmission / reception circuit 20, which is the reference unit. This makes it possible to avoid changes in distance and relative speed caused by differences between the transmission / reception circuits 20.

[0069] Next, in step S150, the control unit 50 reproduces the signals corresponding to the targets received by the first SIMO antenna and the second SIMO antenna (the comparison signals selected in step S140) using DBF.

[0070] Next, in step S160, the control unit 50 detects the correction target component of the correction target circuit by comparing the regeneration results obtained by regenerating the comparison signal using DBF. Then, using the correction target component, a correction coefficient is calculated for matching the phase and amplitude of the second transmission / reception circuit 30 side with the phase and amplitude of the first transmission / reception circuit 20 side. Specifically, the control unit 50 obtains "γ" indicating the phase difference and "A" indicating the amplitude difference by comparing regenerated signals s1 and s2 obtained by regenerating signals corresponding to the target received by each SIMO antenna using DBF.

[0071] Next, in step S170, the control unit 50 performs a correction process to correct the phase and amplitude of the received signals of the receiving antenna elements Rx21 to Rx24 on the second transmission / reception circuit 30 side, using the above-mentioned correction coefficients.

[0072] However, if the difference between the reproduced signals s1 and s2 reproduced by DBF is larger than the signal difference expected in advance, there is a risk that a false image due to clutter or multiple reflections will be detected as a target. For this reason, it is desirable to correct the correction target component of the correction target circuit using the reproduced signals s1 and s2 reproduced by DBF whose difference is equal to or smaller than a predetermined value.

[0073] Next, in step S180, the control unit 50 executes a detection process for the target object. For example, the control unit 50 estimates distance information correlating with the distance to the target object, speed information correlating with the relative speed to the target object, and the target's azimuth based on the received signal corrected in step S170. Then, the control unit 50 detects the target object based on the estimation results of the distance information, speed information, and target's azimuth.

[0074] The radar device 1 described above uses the first transmission / reception circuit 20 as a reference unit and the second transmission / reception circuit 30 as a correction target circuit, and corrects both the phase difference and the amplitude difference occurring between the first transmission / reception circuit 20 and the second transmission / reception circuit 30 as correction target components. The radar device 1 of this embodiment corrects the correction target components of the correction target circuit based on a comparison of detection results of signals corresponding to targets based on received signals at each of the SIMO antennas that overlap when slid in a predetermined direction.

[0075] In such a radar device 1, at least one of the phase error and the amplitude error of the signal occurring between the multiple transmission / reception circuits 20, 30 can be corrected as a correction target component, without making the antenna elements redundant.

[0076] Moreover, the radar device 1 of this embodiment has the following features.

[0077] (1) The radar device 1 uses one of the signals received by the first SIMO antenna and the second SIMO antenna that corresponds to a target as a comparison signal, and corrects the correction target component of the correction target circuit based on a comparison of the detection results of the target based on the comparison signal.

[0078] This makes it possible to appropriately correct the components to be corrected, such as the phase difference or amplitude difference that occurs between the reference circuit and the circuit to be corrected, compared to a method that compensates for the phase difference even when there is no target within the field of view angle of the radar device 1.

[0079] (2) The control unit 50 corrects the correction target component of the correction target circuit by comparing a regeneration result of a signal corresponding to a target received by the first virtual antenna regenerated by DBF with a regeneration result of a signal corresponding to the target received by the second virtual antenna regenerated by DBF. In this way, by comparing regenerated signals obtained by regenerating signals corresponding to targets received by each SIMO antenna by DBF, it is possible to extract a component corresponding to the correction target component.

[0080] (3) If the difference between the reproduced signals resulting from the reproduction in the DBF of the signal corresponding to the target is too large compared to the signal difference expected in advance, there is a risk that a false image due to clutter or multiple reflections may be detected as the target. For this reason, it is preferable that the radar device 1 corrects the correction target component of the correction target circuit using a signal that has a difference between the reproduced signals resulting from the reproduction in the DBF of the signal corresponding to the target received by each SIMO antenna that is equal to or smaller than a predetermined threshold.

[0081] (4) The control unit 50 has, as the target detection unit 51, a distance calculation unit 52 that obtains distance information correlating with the distance to the target, and a speed calculation unit 53 that obtains speed information correlating with the relative speed of the target. The control unit 50 sets, among the signals received by each SIMO antenna, a signal that indicates that the distance to the target based on the distance information is equal to or shorter than a reference distance and that indicates that the relative speed of the target based on the speed information is equal to or shorter than a reference speed, as a comparison signal.

[0082] This allows a signal with a high signal-to-noise ratio and small phase change due to differences in the transmission timing of radio waves from the multiple transmitting antenna elements Tx1 and Tx2 to be used as the comparison signal, making it possible to appropriately determine the correction target component occurring between the reference circuit and the correction target circuit. As a result, it is possible to correct at least one of the phase difference and the amplitude difference of the signals occurring between the multiple transmitting / receiving circuits 20 and 30.

[0083] (Modification of the first embodiment) In the first embodiment, the radar device 1 corrects the correction target components in the correction target circuit regardless of the number of targets detected by the target detection unit 51, but the radar device 1 is not limited to this.

[0084] When there are multiple targets within the viewing angle range of the radar device 1, the signal reproduced by DBF is affected by side lobes of signals corresponding to the other targets, as shown in Fig. 9. For this reason, it is desirable that the control unit 50 corrects the correction target component in the correction target circuit when one target is detected by the target detection unit 51, and does not correct the correction target component in the correction target circuit when two or more targets are detected by the target detection unit 51.

[0085] The control unit 50 in the first embodiment calculates a correction coefficient to match the phase and amplitude of each of the transmission / reception circuits 20, 30, and corrects the phase and amplitude of the reception signal of the receiving antenna elements Rx21 to Rx24 on the second transmission / reception circuit 30 side using the correction coefficient, but is not limited to this. The correction of the phase difference and amplitude difference by the control unit 50 may be realized, for example, by changing the phase and amplitude on the second transmission / reception circuit 30 side using a phase shifter, an amplifier, or the like so that they match the phase and amplitude on the first transmission / reception circuit 20 side. This also applies to the following embodiments.

[0086] As in the first embodiment, the radar device 1 is preferably configured to correct both the phase difference and the amplitude difference of each of the transmission / reception circuits 20 and 30 as the components to be corrected, but is not limited to this. The radar device 1 may be configured to correct either the phase difference or the amplitude difference of each of the transmission / reception circuits 20 and 30 as the components to be corrected. This also applies to the following embodiments.

[0087] In the first embodiment, the first transmission / reception circuit 20 is the reference unit and the second transmission / reception circuit 30 is the circuit to be corrected, but the second transmission / reception circuit 30 may be the reference unit and the first transmission / reception circuit 20 may be the circuit to be corrected. This also applies to the following embodiments.

[0088] As in the first embodiment, it is desirable to use, as the comparison signal, a signal that indicates that the distance to the target is equal to or less than the reference distance and that the relative speed with respect to the target is equal to or less than the reference speed among the signals received by each SIMO antenna, but this is not limited thereto. For example, the control unit 50 may use, as the comparison signal, a signal corresponding to the target among the signals received by each SIMO antenna, without considering the distance to the target or the relative speed with respect to the target. Also, the control unit 50 may use, as the comparison signal, a signal that indicates that the distance to the target is equal to or less than the reference distance among the signals received by each SIMO antenna. Furthermore, the control unit 50 may use, as the comparison signal, a signal that indicates that the relative speed with respect to the target is equal to or less than the reference distance among the signals received by each SIMO antenna, for example. The same applies to the following embodiments.

[0089] The radar device 1 of the first embodiment has an antenna configuration in which the antenna elements constituting the virtual array antenna are not made redundant, but is not limited thereto, and the antenna configuration may be such that the antenna elements constituting the virtual array antenna are made redundant. In other words, the radar device 1 of the present disclosure is also applicable to an antenna configuration in which the antenna elements constituting the virtual array antenna can be made redundant.

[0090] In the first embodiment, the correction of the correction target component is performed every time the target detection process for detecting a target is executed by the radar device 1, but the present invention is not limited to this. The radar device 1 may be configured to correct the correction target component separately from the target detection process for detecting a target.

[0091] Second embodiment Next, a second embodiment will be described with reference to Figures 10 to 13. In this embodiment, differences from the first embodiment will be mainly described.

[0092] As in the first embodiment, it is desirable that the distance between the two transmitting antenna elements Tx1, Tx2 that constitute the transmitting antenna group Tx is a multiple of the distance between the eight receiving antenna elements Rx11 to Rx14, Rx21 to Rx24 that constitute the receiving antenna group Rx.

[0093] However, in an actual product, due to manufacturing errors or the like, the interval between the two transmitting antenna elements Tx1, Tx2 may differ from the interval between the receiving antenna elements Rx11 to Rx14 and Rx21 to Rx24.

[0094] For example, as shown in Fig. 10, in the radar device 1, the transmitting antenna elements Tx1 and Tx2 are arranged at an interval of "5dt", which is five times the reference distance "dt" different from the horizontal reference distance "dh" (reference distance = 5dt in this example). Note that the reference distance "dt" is the horizontal reference distance "dh" plus a difference α due to manufacturing error or the like. This difference α is a value sufficiently small compared to the horizontal reference distance "dh".

[0095] The receiving antenna group Rx is arranged at an interval different from the reference interval (5dt in this example) which is the arrangement interval of the transmitting antenna elements Tx1 and Tx2. However, the receiving antenna elements Rx11 and Rx14 are arranged at an interval close to the reference interval, and the arrangement relationship of the transmitting antenna element Tx2 with respect to the receiving antenna element Rx11 is similar to the arrangement relationship of the transmitting antenna element Tx1 with respect to the receiving antenna element Rx14.

[0096] In such an antenna configuration, the received signal x of the transmitting antenna element Tx1 is received by the receiving antenna elements Rx11 to Rx14. 11 ~x 14 The received signal vector X1 representing the above is expressed by the formula F9 in FIG. 10. Also, the received signal x 11 ~x 14 The received signal vector X2 representing the above is expressed by the formula F10 in FIG.

[0097] In this embodiment, the intervals between the receiving antenna elements Rx11-Rx14 and Rx21-Rx24 do not match the intervals between the transmitting antenna elements Tx1 and Tx2. Therefore, as shown in formulas F9 and F10 in FIG. 10, the receiving signal vectors X1 and X2 of the SIMO antennas are different.

[0098] On the other hand, according to formulas F9 and F10 in Fig. 10, when the azimuth angle θ of the target is substantially zero (when the target is oriented in the center), the difference between the reception signal vectors X1 and X2 caused by the difference in the arrangement intervals of the antenna elements becomes small. In other words, the difference between the reception signal vectors X1 and X2 at each SIMO antenna tends to be small when the target is located closer to the center than to both ends of the detectable range.

[0099] Taking these factors into consideration, the control unit 50 sets as a comparison signal the signal received by each virtual antenna that indicates that the target's azimuth is in the central region closer to the center than either end of the target's detectable range.

[0100] Hereinafter, the comparison signal selection process executed by the control unit 50 of this embodiment will be described with reference to Fig. 11. The process shown in Fig. 11 is executed by the control unit 50 as one process in the target detection process. Note that the process shown in Fig. 11 corresponds to the process of step S140 in Fig. 5 described in the first embodiment.

[0101] 11, in step S141, the control unit 50 selects a signal to be subjected to azimuth estimation based on distance information and speed information from among signals detected as targets. For example, the control unit 50 preferentially selects a signal indicating a short distance and a small relative speed as a signal to be subjected to azimuth estimation.

[0102] Next, in step S142, the control unit 50 performs azimuth estimation of the target corresponding to the signal selected as the target of azimuth estimation. Specifically, the control unit 50 performs simple azimuth estimation based on the received signals at the receiving antenna elements Rx11 to Rx14 connected to the first transmitting / receiving circuit 20 serving as the reference unit.

[0103] Here, it is conceivable to estimate the azimuth of the target based on the signals received by all the receiving antenna elements Rx11-Rx14, Rx21-Rx24, but the estimation accuracy of the azimuth would be reduced due to the phase difference and amplitude difference between the transmitting and receiving circuits 20, 30. For this reason, it is preferable that the azimuth of the target is estimated based on the signals received by the receiving antenna elements Rx11-Rx14 connected to the first transmitting and receiving circuit 20, which is the reference section, as in this embodiment, before the correction of the correction target components.

[0104] Next, in step S143, the control unit 50 determines whether the azimuth of the target estimated by the simple azimuth estimation is in a central region closer to the center than both ends of the detectable range of the target. Here, the central region is a region including the center position (θ=0) of the viewing angle. The central region is set to a range in which the phase difference between the transmission / reception circuits 20 and 30 can be obtained by comparing the received signals at each SIMO antenna.

[0105] If the result of the simple azimuth estimation indicates that the target is within the central region, the control unit 50 sets the signal indicating that the target is within the central region as the comparison signal in step S144, and exits the comparison signal selection process.

[0106] On the other hand, if the estimation result of the simple azimuth estimation indicates that the target is outside the central region, the control unit 50 returns to step S141. Specifically, if the estimation result of the simple azimuth estimation indicates that the target is outside the central region, the control unit 50 next selects a signal indicating a short distance and a small relative speed as a signal to be subjected to azimuth estimation, and again performs azimuth estimation of the target corresponding to the selected signal.

[0107] By such a selection process, a signal indicating that a target is present within the central region is set as the comparison signal. For example, as shown in Fig. 12, when three targets Trg1 to Trg3 exist in different directions, a signal indicating target Trg1 within the central region is set as the comparison signal.

[0108] 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.

[0109] Moreover, the radar device 1 of this embodiment has the following features.

[0110] (1) In the present embodiment, the control unit 50 uses, as a comparison signal, a signal received by each SIMO antenna that indicates that the target azimuth estimated by the simple azimuth estimation process is in a central region closer to the center than both ends of the target detectable range. This makes it possible to appropriately determine the phase difference and amplitude difference occurring between the reference circuit and the correction target circuit even if a phase shift occurs due to an arrangement error of the antenna elements.

[0111] (2) In this embodiment, the control unit 50 preferentially selects signals that indicate a short distance and a small relative speed as signals to be subjected to azimuth estimation. This makes it easier to use signals with a high S / N ratio and small phase changes due to differences in the transmission timing of radio waves from the multiple transmitting antenna elements Tx1 and Tx2 as comparison signals, so that the correction target components occurring between the reference circuit and the correction target circuit can be appropriately obtained.

[0112] (Modification of the second embodiment) As in the second embodiment, it is preferable that the radar device 1 preferentially selects signals indicating a short distance and a small relative speed as signals to be used for azimuth estimation, but this is not essential.

[0113] In the second embodiment, the simplified azimuth estimation is performed based on the received signals at the receiving antenna elements Rx11-Rx14 connected to the first transceiver circuit 20 serving as the reference unit, but is not limited thereto. The radar device 1 may be configured to perform the simplified azimuth estimation of the target based on the received signals at the receiving antenna elements Rx21-Rx24 connected to the second transceiver circuit 30 serving as the correction target unit.

[0114] Third embodiment Next, a third embodiment will be described with reference to Figures 13 to 15. In this embodiment, differences from the first embodiment will be mainly described.

[0115] 13, the first radar unit RU1 of this embodiment includes a plurality of actual transmitting antenna elements Tx11-Tx14, a plurality of actual receiving antenna elements Rx11-Rx14, and a first transceiver circuit 20. The second radar unit RU2 includes a plurality of actual transmitting antenna elements Tx21-Tx24, a plurality of actual receiving antenna elements Rx21-Rx24, and a second transceiver circuit 30.

[0116] The transmitting antenna group Tx and the receiving antenna group Rx of this example will be described with reference to Fig. 14. As shown in Fig. 14, the transmitting antenna group Tx of this example has eight actual transmitting antenna elements Tx11 to Tx14, Tx21 to Tx24. Also, the receiving antenna group Rx of this example has eight actual receiving antenna elements Rx11 to Rx14, Rx21 to Rx24.

[0117] As shown in FIG. 14, the eight transmitting antenna elements Tx11 to Tx14 and Tx21 to Tx24 constituting the transmitting antenna group Tx are arranged side by side in both the horizontal direction U and the vertical direction V when the radar device 1 is mounted on a vehicle.

[0118] In the transmitting antenna group Tx, the transmitting antenna elements Tx11 to Tx14 connected to the first transmitting / receiving circuit 20 are arranged on one side of the horizontal direction U, and the transmitting antenna elements Tx21 to Tx24 connected to the second transmitting / receiving circuit 30 are arranged on the other side of the horizontal direction U.

[0119] Of the transmitting antenna elements Tx11 to Tx14 connected to the first transmission / reception circuit 20, three transmitting antenna elements Tx11, Tx12, and Tx14 are arranged side by side in the vertical direction V, and two transmitting antenna elements Tx12 and Tx13 are arranged side by side in the horizontal direction U.

[0120] Specifically, the transmitting antenna elements Tx12 and Tx13 arranged in the horizontal direction U are arranged at an interval of "3dh", which is three times the predetermined horizontal reference distance "dh". The transmitting antenna elements Tx11, Tx12, and Tx14 arranged in the vertical direction V are arranged at an interval of "dz", which is one time the predetermined vertical reference distance "dz". The intervals between the transmitting antenna elements Tx11, Tx12, and Tx14 may be strictly multiples of the vertical reference distance "dz", 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 contradict the gist of the technology of the present disclosure. This also applies to the intervals between the transmitting antenna elements Tx21 to Tx24 connected to the second transmission / reception circuit 30 and the receiving antenna elements Rx11 to Rx14 and Rx21 to Rx24 arranged in the vertical direction V.

[0121] The vertical reference distance "dz" in this example is set so as to satisfy the following formula F11 when the detection range of the radar device 1 is "±1 / 2·φfov". In this embodiment, φfov is set to "180°" and the vertical reference distance "dz" is set to "1 / 2·λ", where λ is the wavelength of the radio wave.

[0122] 1 / sin(φfov / 180 π) 2 <dz ···(F11) In addition, of the transmitting antenna elements Tx21 to Tx24 connected to the second transmission / reception circuit 30, three transmitting antenna elements Tx21, Tx22, and Tx24 are arranged side by side in the vertical direction V, and two transmitting antenna elements Tx22 and Tx23 are arranged side by side in the horizontal direction U.

[0123] Specifically, the transmitting antenna elements Tx22 and Tx23 aligned in the horizontal direction U are spaced apart by "3dh", which is three times the predetermined horizontal reference distance "dh". The transmitting antenna elements Tx21, Tx22, and Tx24 aligned in the vertical direction V are spaced apart by "dz", which is one time the predetermined vertical reference distance "dz".

[0124] Here, the transmitting antenna element Tx13 on one side of the horizontal direction U and the transmitting antenna element Tx23 on the other side of the horizontal direction U are arranged at an interval of "5dh", which is five times the predetermined horizontal reference distance "dh".

[0125] The receiving antenna group Rx in this embodiment is composed of eight actual receiving antenna elements Rx11 to Rx14, Rx21 to Rx24. The eight receiving antenna elements Rx11 to Rx14, Rx21 to Rx24 constituting the receiving antenna group Rx 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.

[0126] Specifically, the receiving antenna group Rx includes four receiving antenna elements Rx11 to Rx14 connected to the first transmitting / receiving circuit 20. The four receiving antenna elements Rx11 to Rx14 connected to the first transmitting / receiving circuit 20 are arranged side by side in the horizontal direction U at a position close to the transmitting antenna element Tx11 which is one end in the vertical direction V of the transmitting antenna group Tx.

[0127] The receiving antenna group Rx also includes four receiving antenna elements Rx21-Rx24 connected to the second transmitting / receiving circuit 30. The four receiving antenna elements Rx21-Rx24 connected to the second transmitting / receiving circuit 30 are arranged side by side in the horizontal direction U at a position close to the transmitting antenna element Tx14 which is the other end of the transmitting antenna group Tx in the vertical direction V. The receiving antenna elements Rx11-Rx14 in the first row and the receiving antenna elements Rx21-Rx24 in the second row are arranged at an interval of "2dh", which is twice the horizontal reference distance "dh".

[0128] Furthermore, the receiving antenna elements Rx11 to Rx14 in the first row and the receiving antenna elements Rx21 to Rx24 in the second row are arranged to face each other in the vertical direction V. The receiving antenna elements Rx11 to Rx14 in the first row and the receiving antenna elements Rx21 to Rx24 in the second row are arranged at an interval of "3dz", which is three times the vertical reference distance "dz".

[0129] In the radar device 1 of this embodiment, the intervals between the receiving antenna elements Rx11-Rx14, Rx21-Rx24 in the vertical direction V are different from the intervals between the transmitting antenna elements Tx11-Tx14, Tx21-Tx14 in the vertical direction V. In the radar device 1 of this embodiment, the intervals between the receiving antenna elements Rx11-Rx14, Rx21-Rx24 in the horizontal direction U are different from the intervals between the transmitting antenna elements Tx11-Tx14, Tx21-Tx14 in the horizontal direction U.

[0130] A virtual antenna based on this type of antenna configuration is configured as an array antenna with many virtual antenna elements arranged in both the horizontal direction U and the vertical direction V. This makes it possible to detect the position and direction of a target in two different directions.

[0131] For example, a virtual antenna in which reflected waves corresponding to transmitted waves from transmitting antenna elements Tx12 and Tx13 are received by receiving antenna elements Rx11 to Rx14 is a first MIMO antenna shown on the left side in the upper part of Fig. 15. Also, a virtual antenna in which reflected waves corresponding to transmitted waves from transmitting antenna elements Tx22 and Tx23 are received by receiving antenna elements Rx11 to Rx14 is a second MIMO antenna shown on the right side in the upper part of Fig. 15. In this embodiment, one of the first MIMO antenna and the second MIMO antenna corresponds to a "first virtual antenna", and the other corresponds to a "second virtual antenna".

[0132] A virtual antenna (MIMO antenna) including the first MIMO antenna and the second MIMO antenna has an arrangement in which the antenna elements constituting the first MIMO antenna and the antenna elements constituting the second MIMO antenna do not overlap.

[0133] On the other hand, the first MIMO antenna and the second MIMO antenna use the receiving antenna elements Rx11 to Rx14 connected to the first transmitting / receiving circuit 20 as a common antenna element.

[0134] In addition, when one MIMO antenna is slid, it overlaps with the other MIMO antenna. In other words, when the first MIMO antenna is slid in the horizontal direction U, it overlaps with the second MIMO antenna. This makes the target detection accuracy of the first MIMO antenna and the second MIMO antenna equivalent.

[0135] In the radar device 1 of this embodiment configured as described above, the control unit 50 can correct the phase difference and amplitude difference in each of the transmission / reception circuits 20, 30 by comparing the target detection results based on the received signals at each MIMO antenna.

[0136] 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.

[0137] Moreover, the radar device 1 of this embodiment has the following features.

[0138] (1) The radar device 1 of this embodiment is configured as an array antenna in which many virtual antenna elements are arranged in two different directions, and is therefore capable of detecting the position and direction of a target in two different directions. In this radar device 1, as in the first embodiment, at least one of the phase difference and the amplitude difference of signals occurring between the multiple transmission / reception circuits 20, 30 can be corrected.

[0139] (Modification of the third embodiment) In the radar device 1 of the third embodiment, the transmitting antenna elements Tx11-Tx14, Tx21-Tx24 and the receiving antenna elements Rx11-Rx14, Rx21-Rx24 are arranged side by side in the horizontal direction U and the vertical direction V, respectively, but are not limited to this. In the radar device 1, the transmitting antenna elements Tx11-Tx14, Tx21-Tx24 and the receiving antenna elements Rx11-Rx14, Rx21-Rx24 may be arranged side by side in two directions other than the horizontal direction U and the vertical direction V. This also applies to the subsequent embodiments.

[0140] In the third embodiment, the phase difference and amplitude difference in each of the transmission / reception circuits 20 and 30 are corrected by comparing the target detection results based on the reception signals at a virtual antenna having antenna elements arranged in the horizontal direction U, but the present invention is not limited to this. The radar device 1 may be configured to correct the phase difference and amplitude difference in each of the transmission / reception circuits 20 and 30 by comparing the target detection results based on the reception signals at a virtual antenna having antenna elements arranged in the vertical direction V. This is similar to the embodiments other than the third embodiment.

[0141] (Fourth embodiment) Next, a fourth embodiment will be described with reference to Fig. 16 to Fig. 19. In this embodiment, differences from the second embodiment will be mainly described.

[0142] As shown in FIG. 16, the radar device 1 of this embodiment includes a first radar unit RU1, a second radar unit RU2, a third radar unit RU3, and a fourth radar unit RU4.

[0143] The first radar unit RU1 includes four transmitting antenna elements Tx11-Tx14, four receiving antenna elements Rx11-Rx14, and a first transceiver circuit 20. The second radar unit RU2 includes four transmitting antenna elements Tx21-Tx24, four receiving antenna elements Rx21-Rx24, and a second transceiver circuit 30. The third radar unit RU3 includes four transmitting antenna elements Tx31-Tx34, four receiving antenna elements Rx31-Rx34, and a third transceiver circuit 40. The fourth radar unit RU3 includes four transmitting antenna elements Tx41-Tx44, four receiving antenna elements Rx41-Rx44, and a fourth transceiver circuit 60.

[0144] The transmitting antenna group Tx and the receiving antenna group Rx of this example will be described with reference to Fig. 17. As shown in Fig. 17, the transmitting antenna group Tx of this example has 16 actual transmitting antenna elements Tx11-Tx14, Tx21-Tx24, Tx31-Tx34, and Tx41-Tx44. Also, the receiving antenna group Rx of this example has 16 actual receiving antenna elements Rx11-Rx14, Rx21-Rx24, Rx31-Rx34, and Rx41-Rx44.

[0145] As shown in FIG. 17, 16 transmitting antenna elements Tx11 to Tx14, Tx21 to Tx24, Tx31 to Tx34, and Tx41 to Tx44 constituting the transmitting antenna group Tx are arranged side by side in the horizontal direction U and the vertical direction V.

[0146] In the transmitting antenna group Tx, transmitting antenna elements Tx11 to Tx14 connected to the first transceiver circuit 20 and transmitting antenna elements Tx31 to Tx34 connected to the third transceiver circuit 40 are arranged on one side of the horizontal direction U with an interval (1dz in this example) between them.

[0147] In addition, transmitting antenna elements Tx21 to Tx24 connected to the second transceiver circuit 30 and transmitting antenna elements Tx41 to Tx44 connected to the fourth transceiver circuit 60 are arranged on the other side of the horizontal direction U with an interval (1dz in this example) between them.

[0148] Furthermore, the transmitting antenna elements Tx11-Tx14 connected to the first transmission / reception circuit 20 and the transmitting antenna elements Tx21-Tx24 connected to the second transmission / reception circuit 30 are arranged on one side of the vertical direction V with an interval (13dh in this example) in the horizontal direction U. They are arranged to face each other. Then, the transmitting antenna elements Tx31-Tx34 connected to the third transmission / reception circuit 40 and the transmitting antenna elements Tx41-Tx44 connected to the fourth transmission / reception circuit 40 are arranged on the other side of the vertical direction V with an interval (13dh in this example) in the horizontal direction U.

[0149] The transmitting antenna elements Tx11 to Tx14 connected to the first transmission / reception circuit 20 are arranged at intervals of "3dh", which is three times the horizontal reference distance "dh", in the horizontal direction U, and at intervals of "dz", which is one time the vertical reference distance "dz", in the vertical direction V. Note that the elements connected to the second transmission / reception circuit 30, the third transmission / reception circuit 40, and the fourth transmission / reception circuit 60 are similar to those connected to the first transmission / reception circuit 20, and therefore will not be described here.

[0150] Next, the receiving antenna group Rx will be described. The receiving antenna group Rx includes 16 receiving antenna elements Rx11 to Rx14, Rx21 to Rx24, Rx31 to Rx34, and Rx41 to Rx44 arranged in the horizontal direction U and the vertical direction V.

[0151] Specifically, the receiving antenna group Rx includes four receiving antenna elements Rx11 to Rx14 connected to a first transmission / reception circuit 20 and four receiving antenna elements Rx21 to Rx24 connected to a second transmission / reception circuit 30, which are arranged side by side in the horizontal direction U on one side of the vertical direction V.

[0152] In addition, the receiving antenna group Rx has four receiving antenna elements Rx31 to Rx34 connected to the third transceiver circuit 40 and four receiving antenna elements Rx41 to Rx44 connected to the fourth transceiver circuit 60 arranged side by side in the horizontal direction U on the other side of the vertical direction V.

[0153] The receiving antenna elements Rx11-Rx14, Rx21-Rx24 in the first row and the receiving antenna elements Rx31-Rx34, Rx41-Rx44 in the second row are spaced apart by "2dh", which is twice the horizontal reference distance "dh". Furthermore, the receiving antenna elements Rx11-Rx14, Rx21-Rx24 in the first row and the receiving antenna elements Rx31-Rx34, Rx41-Rx44 in the second row are spaced apart by "4dz", which is four times the vertical reference distance "dz", in the vertical direction V.

[0154] In the radar device 1 of this embodiment, the spacing in the vertical direction V of the antenna elements constituting the receiving antenna group Rx is different from the spacing in the vertical direction V of the antenna elements constituting the transmitting antenna group Tx. Also, in the radar device 1 of this embodiment, the spacing in the horizontal direction U of the antenna elements constituting the receiving antenna group Rx is different from the spacing in the horizontal direction U of the antenna elements constituting the transmitting antenna group Tx.

[0155] A virtual antenna based on this type of antenna configuration is configured as an array antenna with many virtual antenna elements arranged in both the horizontal direction U and the vertical direction V. This makes it possible to detect the position and direction of a target in two different directions.

[0156] For example, a virtual antenna in which reflected waves corresponding to transmitted waves from transmitting antenna elements Tx11, Tx12 connected to the first transmission / reception circuit 20 are received by receiving antenna elements Rx11-Rx14 is the first MIMO antenna shown in Fig. 18. A virtual antenna in which reflected waves corresponding to transmitted waves from transmitting antenna elements Tx11, Tx12 connected to the first transmission / reception circuit 20 are received by receiving antenna elements Rx21-Rx24 connected to the second transmission / reception circuit 30 is the second MIMO antenna shown in Fig. 18.

[0157] Moreover, a virtual antenna in which reflected waves corresponding to transmitted waves from transmitting antenna elements Tx11, Tx12 connected to the first transmitting / receiving circuit 20 are received by receiving antenna elements Rx31-Rx34 connected to the third transmitting / receiving circuit 40 is the third MIMO antenna shown in Fig. 19. A virtual antenna in which reflected waves corresponding to transmitted waves from transmitting antenna elements Tx11, Tx12 connected to the first transmitting / receiving circuit 20 are received by receiving antenna elements Rx41-Rx44 connected to the fourth transmitting / receiving circuit 60 is the fourth MIMO antenna shown in Fig. 19. In this embodiment, a part of each MIMO antenna corresponds to a "first virtual antenna", and another MIMO antenna corresponds to a "second virtual antenna".

[0158] The first to fourth MIMO antennas use the transmitting antenna elements Tx11 and Tx12 connected to the first transmitting / receiving circuit 20 as a common antenna element.

[0159] In addition, when some of the MIMO antennas are slid, they overlap with other MIMO antennas. That is, when some of the MIMO antennas are slid in the horizontal direction U or the vertical direction V, they overlap with other MIMO antennas. This makes the first to fourth MIMO antennas have the same target detection accuracy. This is also true when using the transmitting antenna elements Tx13 and Tx14 connected to the first transmitting / receiving circuit 20.

[0160] In the radar device 1 of this embodiment configured as described above, the control unit 50 can correct the phase difference and amplitude difference in each of the transmission / reception circuits 20, 30 by comparing the target detection results based on the received signals at each MIMO antenna.

[0161] For example, the first transceiver circuit 20 can be set as the "reference unit", and the other transceiver circuits 30, 40, 60 excluding the "reference unit" can be set as "circuits to be corrected", and one of the phase difference and amplitude difference in the "circuits to be corrected" relative to the "reference unit" can be corrected as the component to be corrected.

[0162] In addition, something other than the first transmission / reception circuit 20 can be set as a “reference part”, other circuits including the first transmission / reception circuit 20 can be set as a “circuit to be corrected”, and one of the phase difference and amplitude difference in the “circuit to be corrected” relative to the “reference part” can be corrected as the component to be corrected.

[0163] Furthermore, even when using transmitting antenna elements Tx13 and Tx14 connected to the first transmission / reception circuit 20, the components to be corrected can be obtained in the same manner as when using transmitting antenna elements Tx11 and Tx12 connected to the first transmission / reception circuit 20.

[0164] The radar device 1 of the present embodiment thus configured is capable of calculating a plurality of correction coefficients for correcting the correction target component. When a plurality of correction coefficients for correcting the correction target component can be calculated, the radar device 1 corrects the correction target component of the correction target circuit by using an average value of the plurality of correction coefficients.

[0165] The rest is the same as in the second embodiment. The radar device 1 of this embodiment can obtain the same effects as in the second embodiment, which are achieved by a configuration common to the second embodiment or an equivalent configuration.

[0166] Moreover, the radar device 1 of this embodiment has the following features.

[0167] (1) When multiple correction coefficients for correcting the correction target component are obtained, the control unit 50 corrects the correction target component of the correction target circuit using an average value of the multiple correction coefficients. This makes it possible to appropriately correct the phase difference or amplitude difference occurring between the reference circuit and the correction target circuit.

[0168] (Modification of the fourth embodiment) As in the fourth embodiment, it is desirable that the control unit 50 calculates a plurality of correction coefficients for correcting the components to be corrected, and corrects the components to be corrected of the circuit to be corrected using an average value of the plurality of correction coefficients, but this is not essential.

[0169] (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.

[0170] In the above embodiment, a specific antenna configuration of the radar device 1 is exemplified, but the antenna configuration of the radar device 1 is not limited to the above, and may be an antenna configuration different from the above. The number of antenna elements constituting the transmitting antenna group Tx and the number of antenna elements constituting the receiving antenna group Rx may be different from the above. In addition, the number of transmitting and receiving circuits may also be different from the above.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] 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]

[0176] 1. Radar equipment 20, 30, 40, 60 Transmitter / receiver circuit 54 Correction processing section Tx Transmitting antenna group Rx receiving antennas

Claims

1. A radar device that detects targets using radio waves, A transmitting antenna group (Tx) including a plurality of transmitting antenna elements; A receiving antenna group (Rx) including a plurality of receiving antenna elements; a plurality of transmitting / receiving circuits (20, 30, 40, 60) to which the plurality of transmitting antenna elements and the plurality of receiving antenna elements are connected; a correction processing unit (55) that uses a part of the plurality of transmission / reception circuits as a reference circuit and the other transmission / reception circuits excluding the reference circuit as a correction target circuit, and corrects at least one of a phase difference and an amplitude difference of a signal generated between the reference circuit and the correction target circuit as a correction target component, A virtual antenna using both the transmitting antenna element and the receiving antenna element connected to the reference circuit is defined as a first virtual antenna, and a virtual antenna using one of the transmitting antenna element and the receiving antenna element connected to the reference circuit and the other of the transmitting antenna element and the receiving antenna element connected to the correction target circuit is defined as a second virtual antenna. the first virtual antenna has an antenna configuration in which the first virtual antenna overlaps with the second virtual antenna when the first virtual antenna is virtually slid in a predetermined direction, the correction processing unit corrects the correction target component of the correction target circuit based on a comparison between a detection result of a signal corresponding to the target based on the received signal at the first virtual antenna and a detection result of a signal corresponding to the target based on the received signal at the second virtual antenna.

2. a target detection unit (51) for detecting the target based on a reception result at the receiving antenna element of a reflected wave corresponding to a transmission wave transmitted from at least one of the transmitting antenna elements, 2. The radar device according to claim 1, wherein the correction processing unit uses a signal received by the first virtual antenna and the second virtual antenna that corresponds to the target detected by the target detection unit as a comparison signal, and corrects the correction target component of the correction target circuit based on a comparison of a detection result of the target based on the comparison signal.

3. 3. The radar device according to claim 2, wherein the correction processing unit corrects the correction target component of the correction target circuit by comparing a regeneration result obtained by regenerating, through digital beam forming, a signal corresponding to the target received by the first virtual antenna and a regeneration result obtained by regenerating, through the digital beam forming, a signal corresponding to the target received by the second virtual antenna.

4. 4. The radar device according to claim 3, wherein the correction processing unit corrects the correction target component of the correction target circuit by using a signal that is a regenerated signal resulting from the digital beamforming of a signal corresponding to the target and that is received by the first virtual antenna and the second virtual antenna, the difference between which is equal to or smaller than a predetermined threshold.

5. The target detection unit has a distance calculation unit (52) that calculates distance information having a correlation with the distance to the target based on the reception result, 5. The radar device according to claim 3, wherein the correction processing unit determines, as the comparison signal, one of the signals received by the first virtual antenna and the second virtual antenna that indicates that a distance to the target based on the distance information is within a reference distance.

6. The target detection unit has a speed calculation unit (53) that calculates speed information having a correlation with a relative speed with respect to the target based on the reception result, 5. The radar device according to claim 3, wherein the correction processing unit determines, as the comparison signal, one of the signals received by the first virtual antenna and the second virtual antenna that indicates that a relative velocity of the target based on the velocity information is within a reference velocity.

7. The target detection unit includes: a distance calculation unit (52) for calculating distance information having a correlation with the distance to the target based on the reception result; a speed calculation unit (53) for calculating speed information having a correlation with a relative speed with respect to the target based on the reception result, 5. The radar device according to claim 3, wherein the correction processing unit determines, as the comparison signal, one of the signals received by the first virtual antenna and the second virtual antenna, which indicates that a distance to the target based on the distance information is within a reference distance and which indicates that a relative velocity of the target based on the velocity information is within a reference velocity.

8. The target detection unit has a direction estimation unit (54) that estimates a direction of the target based on the reception result, 5. The radar device according to claim 3, wherein the correction processing unit determines, as the comparison signal, one of the signals received by the first virtual antenna and the second virtual antenna, which indicates that the azimuth of the target estimated by the azimuth estimation unit is in a central region closer to a center than both ends of a detectable range of the target.

9. The correction processing unit: correcting the correction target component in the correction target circuit when one of the targets is detected by the target detection unit; 4. The radar device according to claim 2, wherein when two or more targets are detected by the target detection unit, the correction target component in the correction target circuit is not corrected.

10. 3. The radar device according to claim 1, wherein, when a plurality of correction coefficients for correcting the correction target component are obtained, the correction processing unit corrects the correction target component of the correction target circuit using an average value of the plurality of correction coefficients.

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