Radar device

Abstract

A radar device is provided with: a plurality of transmission antennas arranged at equal intervals and a plurality of reception antennas arranged at equal intervals; ns transmission circuits; nr receiving circuits; and a control unit. And each of Ns and Nr is an integer of 2 or more. The plurality of transmission antennas and the plurality of reception antennas are configured such that, among a set of groups of virtual antennas in which virtual positions overlap between groups of virtual antennas and combinations of transmission circuits and reception circuits do not match, unique groups of virtual antennas in which combinations of transmission circuits and reception circuits do not overlap with other groups include at least Ns + Nr-2 groups. The control unit compensates for at least one of a phase difference and an amplitude difference between different transmission circuits and at least one of a phase difference and an amplitude difference between different reception circuits on the basis of a result of comparison of received signals of virtual antennas in a unique group of at least Ns + Nr-2 groups.

Description

[0001] Cross-reference to related applications

[0002] This application is based on patent application No. 2023-55858 filed in Japan on March 30, 2023, and the contents of the basic application are cited in their entirety by reference. Technical Field

[0003] The present disclosure relates to radar technology. Background Art

[0004] Patent Document 1 discloses a radar device comprising: multiple receiving antennas provided on multiple receiving circuits; a first transmitting antenna and a second transmitting antenna; and a phase compensator. The first and second transmitting antennas are arranged at a predetermined distance from the receiving antennas so that the receiving antennas virtually overlap. The phase compensator compensates for the phase difference between the receiving circuits of reflected waves transmitted from the first and second transmitting antennas based on a comparison of received signals received by the virtually overlapping receiving antennas.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-60732.

[0008] The radar device of Patent Document 1 can only compensate for phase differences between different receiving circuits. However, errors in received signals arise from factors other than differences in the receiving circuits, making it difficult to ensure accurate compensation. Furthermore, the radar device of Patent Document 1 reduces spatial resolution due to the shortened aperture length, which virtually overlaps the receiving antennas. Therefore, the radar device of Patent Document 1 struggles to achieve both accurate compensation and spatial resolution. Summary of the Invention

[0009] An object of the present disclosure is to provide a radar device capable of achieving both compensation accuracy and spatial resolution.

[0010] The following describes the technical means of the present disclosure for solving the problems. In addition, the symbols in parentheses described in the scope of the patent claims indicate the correspondence relationship with the specific technical means described in the embodiments described below, and do not limit the technical scope of the present disclosure.

[0011] A radar device according to a first aspect of the present disclosure includes:

[0012] multiple transmit antennas and multiple receive antennas;

[0013] Ns transmitting circuits, each of which is connected to the transmitting antenna and outputs a transmitting signal;

[0014] Nr receiving circuits, each receiving circuit being connected to the receiving antenna and acquiring a received signal; and

[0015] a control unit that processes the received signal,

[0016] The Ns and Nr are integers greater than 2,

[0017] At least one of the plurality of transmitting antennas and the plurality of receiving antennas is arranged at unequal intervals, and the plurality of transmitting antennas and the plurality of receiving antennas are arranged so that, among groups of virtual antennas assumed for each of the plurality of receiving antennas according to a phase difference of the received signals between the receiving antennas, the set of groups of virtual antennas whose virtual positions overlap and whose combinations of the transmitting circuits and the receiving circuits do not coincide with each other includes at least Ns+Nr-2 unique groups, wherein the unique groups are groups of virtual antennas whose combinations of the transmitting circuits and the receiving circuits do not overlap with those of other groups.

[0018] The control unit performs compensation processing, which compensates for at least one of the phase difference and amplitude difference between different transmitting circuits and at least one of the phase difference and amplitude difference between different receiving circuits based on the comparison results of the received signals between the virtual antennas in the unique group of at least Ns+Nr-2 groups.

[0019] According to this first embodiment, based on the comparison results of the received signals between virtual antennas in at least Ns+Nr-2 unique groups, it is possible to compensate for at least one of the phase and amplitude differences between different transmitting circuits, and at least one of the phase and amplitude differences between different receiving circuits. This allows for compensation not only between different receiving circuits, but also between different transmitting circuits. Furthermore, by arranging at least one of the transmitting and receiving antennas at unequal intervals, the virtual antenna aperture length can be increased compared to a case where they are arranged at equal intervals. This allows for a balance between compensation accuracy and spatial resolution.

[0020] A radar device according to a second aspect of the present disclosure includes:

[0021] multiple transmit antennas and multiple receive antennas;

[0022] Ns transmitting circuits, each of which is connected to the transmitting antenna and outputs a transmitting signal;

[0023] Nr receiving circuits, each receiving circuit being connected to the receiving antenna and acquiring a received signal; and

[0024] a control unit that processes the received signal,

[0025] The Ns and Nr are integers greater than 2,

[0026] At least one of the plurality of transmitting antennas and the plurality of receiving antennas is arranged at unequal intervals,

[0027] And the multiple transmitting antennas and the multiple receiving antennas are configured as follows:

[0028] Among the groups of virtual antennas assumed for each of the transmitting antennas for the plurality of receiving antennas according to the phase difference of the received signals between the receiving antennas, the set of groups of virtual antennas whose virtual positions overlap and whose combinations of the transmitting circuits and the receiving circuits do not coincide with each other includes at least Ns+Nr-2 unique groups, each of which is a group of virtual antennas whose combinations of the transmitting circuits and the receiving circuits do not overlap with those of other groups;

[0029] comprising at least one group of different wiring lengths, wherein the different wiring length group is a group of the virtual antennas whose virtual positions overlap and whose wiring lengths are inconsistent,

[0030] and the total number of belonging groups is at least Ns+Nr-1 groups, and the belonging groups are groups of the virtual antennas belonging to at least one of the unique group and the different wiring length groups,

[0031] The control unit performs compensation processing, which compensates for at least one of the phase difference and amplitude difference corresponding to the wiring length difference between the virtual antennas in the group belonging to at least Ns+Nr-1 groups, at least one of the phase difference and amplitude difference between different transmitting circuits, and at least one of the phase difference and amplitude difference between different receiving circuits based on the comparison result of the received signals between the virtual antennas in the group belonging to at least Ns+Nr-1 groups.

[0032] According to this second embodiment, based on the comparison results of the received signals between virtual antennas in at least Ns+Nr-1 groups, it is possible to compensate for at least one of the phase difference and amplitude difference between different transmitting circuits, at least one of the phase difference and amplitude difference between different receiving circuits, and at least one of the phase difference and amplitude difference corresponding to the wiring length difference between virtual antennas. Therefore, it is possible to compensate for errors between different transmitting circuits and errors caused by wiring length differences, in addition to errors between different receiving circuits. Furthermore, by arranging at least one of the transmitting and receiving antennas at unequal intervals, the opening length of the virtual antenna can be increased compared to a case where they are arranged at equal intervals. Therefore, it is possible to achieve a balance between compensation accuracy and spatial resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1This is a schematic diagram showing the basic configuration of the radar device in the first embodiment.

[0034] Figure 2 Schematic diagram showing an example of a combination of a transmitting circuit and a transmitting antenna, and a receiving circuit and a receiving antenna in the first embodiment.

[0035] Figure 3 It is a schematic diagram showing an example of arrangement of transmitting antennas and receiving antennas in the first embodiment.

[0036] Figure 4 It is a schematic diagram showing a virtual antenna assumed in the first embodiment.

[0037] Figure 5 This is a table showing an example of a virtual antenna group used for compensation processing.

[0038] Figure 6 is a block diagram showing the functional configuration of a control unit according to the first embodiment.

[0039] Figure 7 This is a flowchart showing a control flow according to the first embodiment.

[0040] Figure 8 Schematic diagram showing an example of a combination of a transmitting circuit and a transmitting antenna, and a receiving circuit and a receiving antenna in the second embodiment.

[0041] Figure 9 It is a schematic diagram showing an example of arrangement of transmitting antennas and receiving antennas in the second embodiment.

[0042] Figure 10 Schematic diagram showing a virtual antenna assumed in the second embodiment.

[0043] Figure 11 is a schematic diagram showing overlapping antennas.

[0044] Figure 12 Schematic diagram showing an example of a combination of a transmitting circuit and a transmitting antenna, and a receiving circuit and a receiving antenna in the third embodiment.

[0045] Figure 13 It is a schematic diagram showing an example of arrangement of transmitting antennas and receiving antennas in the third embodiment.

[0046] Figure 14 It is a schematic diagram showing a virtual antenna assumed in the third embodiment.

[0047] Figure 15 This is a graph showing the relationship between wiring length difference and phase error.

[0048] Figure 16This is a table showing an example of a virtual antenna group used for compensation processing.

[0049] Figure 17 This is a graph showing the relative relationship of wiring lengths in the fourth embodiment.

[0050] Figure 18 It is a schematic diagram showing an example of the arrangement of transmitting antennas and receiving antennas in another embodiment.

[0051] Figure 19 Schematic diagram showing the virtual positions of virtual antennas in another embodiment. DETAILED DESCRIPTION

[0052] Hereinafter, multiple embodiments of the present disclosure will be described based on the accompanying drawings. In addition, in each embodiment, the same symbols may be used to mark corresponding components, and repeated descriptions may be omitted. In addition, when only a portion of a structure is described in each embodiment, the structure of other embodiments previously described can be applied to the remaining portions of the structure. In addition, in addition to the combination of structures explicitly described in the description of each embodiment, as long as there are no special obstacles to the combination, the structures of multiple embodiments can be partially combined with each other even if not explicitly stated.

[0053] (First embodiment)

[0054] Regarding the first embodiment of the present disclosure, using Figures 1 to 7 A radar device 1 is mounted on a mobile object, such as a vehicle. The radar device 1 transmits a transmission signal and receives the transmission signal reflected by an object as a received signal. The radar device 1 then detects target object information, such as the distance to the object that reflected the transmission signal, the relative speed to the target object, and the direction of the target object.

[0055] Target object information output from radar device 1 is input to an onboard ECU (Electronic Control Unit) via an onboard network such as CAN (Control Area Network (registered trademark)) or Ethernet (registered trademark). Based on the acquired target object information for each target, the onboard ECU executes various processes for autonomous driving and advanced driver assistance.

[0056] Examples of processing based on object information include collision avoidance processing and warning processing. Collision avoidance processing involves controlling the braking system, steering system, and other systems to avoid collision with an object based on object information. Warning processing involves alerting the driver to the possibility of a collision with an object based on object information.

[0057] like Figure 1 As shown in the basic configuration, radar device 1 of this embodiment includes an oscillator 2, multiple transmission circuits 3, multiple transmission antennas TX, multiple reception antennas RX, multiple reception circuits 4, a temperature sensor 5, and a control unit 6. Radar device 1 utilizes a so-called MIMO (Multiple-Input-Multiple-Output) radar system, which increases the number of reception antennas RX by transmitting transmission signals from multiple transmission antennas TX beyond the actual number of antennas.

[0058] Oscillator 2 receives a control signal from control unit 6 and generates a modulated signal based on the control signal. The modulated signal is, for example, a so-called chirp signal whose frequency varies over time. The modulated signal is distributed and output to the various channels of transmitting circuit 3 and receiving circuit 4. Hereinafter, the modulated signal output from oscillator 2 to transmitting circuit 3 is referred to as the transmitted signal. Furthermore, the modulated signal output from oscillator 2 to receiving circuit 4 is referred to as the local signal.

[0059] The transmitting circuit 3 and receiving circuit 4 are each primarily composed of semiconductor integrated circuit devices such as MMICs (Monolithic Microwave Integrated Circuits). The transmitting circuit 3 is connected to the transmitting antenna TX and outputs a transmission signal to the transmitting antenna TX. Assuming that the number of transmitting circuits 3 mounted on a single radar device 1 is Ns, where Ns is an integer greater than or equal to 2. The transmitting circuit 3 includes the same number of amplifiers 30 as the number of connected transmitting antennas TX. The amplifiers 30 amplify the transmission signal output from the oscillator 2 and output it to the corresponding transmitting antenna TX.

[0060] The transmitting antenna TX converts the electrical signal supplied from the oscillator 2 as a transmission signal into a radio wave signal and transmits it to the outside world. The transmitting antenna TX is configured to include at least one antenna element. For example, the transmitting antenna TX is a patch antenna comprising multiple flat antenna elements. The antenna elements are arranged on the surface of a dielectric substrate, on the side opposite the ground plane, on one side of the dielectric substrate. The multiple antenna elements are connected in series, for example, via a power supply line that supplies the electrical signal.

[0061] The receiving antenna RX receives as a received signal a radio wave signal including a transmission signal reflected by an external reflector. The receiving antenna RX is connected to a corresponding receiving circuit 4. The configuration of the transmitting antenna TX and the receiving antenna RX will be described later.

[0062] The receiving antenna RX converts the received signal, which is a radio wave signal, into an electrical signal and outputs it to the corresponding receiving circuit 4. The receiving antenna RX is configured as a patch antenna having at least one antenna element connected in series via a feed line, similar to the transmitting antenna TX.

[0063] The receiving circuit 4 is connected to the receiving antenna RX and acquires the received signal received by the receiving antenna RX. Assuming that the number of receiving circuits 4 mounted on one radar device 1 is Nr, where Nr is an integer greater than or equal to 2. The receiving circuit 4 includes the same number of amplifiers 40 and signal mixers 41 as the number of connected receiving antennas RX.

[0064] Amplifier 40 amplifies the received signal received by the receiving antenna and outputs it to signal mixer 41. Signal mixer 41 generates a beat signal by mixing the local signal from oscillator 2 with the received signal. The generated beat signal is an interference signal representing the frequency difference between the received signal and the local signal. The beat signal is filtered out by a low-pass filter (not shown) to remove high-frequency components that deviate from the frequency difference between the received signal and the local signal. The beat signal is then output to control unit 6 as signal data related to the received signal.

[0065] The temperature sensor 5 detects the temperature inside the radar device 1. The temperature sensor 5 includes, for example, a thermistor and outputs temperature information corresponding to the resistance value of the thermistor. The temperature sensor 5 detects the temperature information of each of the transmitting circuit 3 and the receiving circuit 4 and outputs it to the control unit 6.

[0066] The control unit 6 is a control unit including at least one dedicated computer. The dedicated computer constituting the control unit 6 may be, for example, an ECU (Electronic Control Unit) dedicated to controlling the radar device 1 .

[0067] The dedicated computers constituting the control unit 6 each have at least one memory 6a and a processor 6b. The memory 6a is a non-transitory tangible storage medium such as at least one of a semiconductor memory, a magnetic medium, and an optical medium, and stores computer-readable programs and data in a non-temporary manner. The storage here may refer to storage in which data is retained even when the sensor system is turned on or off, or may refer to temporary storage in which data is deleted due to the start-up or shutdown of the sensor system. The processor 6b may include, for example, at least one of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a RISC (Reduced Instruction Set Computer)-CPU, a DFP (Data Flow Processor), and a GSP (Graph Streaming Processor) as a core. Alternatively, the processor 6b may be at least one of a digital circuit and an analog circuit. The digital circuit herein refers to, for example, at least one of an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), an SOC (System on a Chip), a PGA (Programmable Gate Array), and a CPLD (Complex Programmable Logic Device). Furthermore, such a digital circuit may include a memory 6 a storing a program.

[0068] The control unit 6 processes the multiple beat signals output from the multiple receiving circuits 4 to perform angle measurement processing to calculate the angle of the reflecting object relative to the radar device 1. The radar device 1 uses a MIMO system to virtually ensure that the number of receiving antennas RX exceeds the actual number, thereby ensuring relatively high angular resolution. Furthermore, the control unit 6 performs compensation processing to compensate for phase and amplitude differences between signals generated between different transmitting circuits 3 and different receiving circuits 4, thereby ensuring relatively high angle measurement accuracy.

[0069] For the above compensation process, each transmitting antenna TX and receiving antenna RX is installed in a predetermined configuration. Figures 2 to 4 The specific example shown illustrates the configuration of transmit antennas TX and receive antennas RX.

[0070] Multiple transmit antennas TX and multiple receive antennas RX are used to assume multiple virtual antennas V for each transmit antenna TX, corresponding to the phase difference of the received signal between the receive antennas RX. The virtual position of each virtual antenna V is defined by the relative position of the corresponding transmit antenna TX with respect to the other transmit antennas TX and the relative position of the corresponding receive antenna RX with respect to the other receive antennas RX.

[0071] The transmitting antenna TX and the receiving antenna RX are configured so that, among the groups of virtual antennas V assumed for each transmitting antenna TX, in the set of groups of virtual antennas whose virtual positions overlap and whose combinations of the transmitting circuit 3 and the receiving circuit 4 are inconsistent, the number of groups of virtual antennas V in which the combination of the transmitting circuit 3 and the receiving circuit 4 does not overlap with that of other groups, i.e., the number of unique groups, is at least Ns+Nr-2 groups.

[0072] As an example, assume that a radar device 1 is equipped with four transmitting antennas TX and six receiving antennas RX. In this example, the number of transmitting circuits 3 is Ns = 2, and the number of receiving circuits 4 is Nr = 2. In this case, Figure 2 As shown, the number of channels in one transmitting circuit 3 is at least two, and the number of channels in one receiving circuit 4 is at least three. Hereinafter, one transmitting circuit 3 is referred to as the first transmitting circuit 3_1, and the other as the second transmitting circuit 3_2. Furthermore, one receiving circuit 4 is referred to as the first receiving circuit 4_1, and the other as the second receiving circuit 4_2. In this embodiment, each circuit is mounted on multiple circuit chips C. Specifically, the first transmitting circuit 3_1 and the first receiving circuit 4_1 are mounted on the same first circuit chip C1. Furthermore, the second transmitting circuit 3_2 and the second receiving circuit 4_2 are mounted on the same second circuit chip C2. Furthermore, the wiring lengths of all wiring lines Wt between the transmitting antenna TX and the corresponding transmitting circuit 3 are substantially the same. Furthermore, the wiring lengths of all wiring lines Wr between the receiving antenna RX and the corresponding receiving circuit 4 are substantially the same.

[0073] In the following, the four transmit antennas TX and the six receive antennas RX are sometimes denoted by different symbols to distinguish them. Specifically, the two transmit antennas TX connected to the first transmit circuit 3_1 are referred to as transmit antennas TX1_1 and TX1_2, and the two transmit antennas TX connected to the second transmit circuit 3_2 are referred to as transmit antennas TX2_1 and TX2_2. Furthermore, the three receive antennas RX connected to the first receive circuit 4_1 are referred to as receive antennas RX1_1, RX1_2, and RX1_3, and the three receive antennas RX connected to the second receive circuit 4_2 are referred to as receive antennas RX2_1, RX2_2, and RX2_3.

[0074] In this case, the transmitting antennas TX and receiving antennas RX are arranged so that, within the aforementioned virtual antenna group V, the number of groups in which the combination of transmitting circuit 3 and receiving circuit 4 does not overlap with other groups is at least Ns + Nr - 2, or two groups. In this embodiment, the transmitting antennas TX and receiving antennas RX are arranged one-dimensionally. Here, one-dimensional arrangement means arrangement along a single reference direction.

[0075] exist Figure 3 In the example shown, transmit antennas TX1_1, TX1_2, TX2_1, and TX2_2 are arranged in order from one side to the other in the X direction, which serves as the reference direction. Transmit antenna TX1_1 and transmit antenna TX1_2 are arranged with a gap of 6d between them. Transmit antenna TX1_2 and transmit antenna TX2_1 are arranged with a gap of 4d between them. Furthermore, transmit antenna TX2_1 and transmit antenna TX2_2 are arranged with a gap of 6d between them.

[0076] Furthermore, the receiving antennas RX1_1 , RX1_2 , RX2_1 , RX2_2 , RX2_3 , and RX1_3 are arranged in this order from one side to the other side in the reference direction at intervals d.

[0077] For each of the transmission antennas TX1_1, TX1_2, TX2_1, and TX2_2, six virtual antennas V are assumed, which is the number of the reception antennas RX. Therefore, a total of 24 virtual antennas V are assumed.

[0078] Here, the multiple virtual antennas V assumed for transmit antenna TX1_1 are virtual antennas V1, V2, V3, V4, V5, and V6, from one side to the other. The multiple virtual antennas V assumed for transmit antenna TX1_2 are virtual antennas V7, V8, V9, V10, V11, and V12, from one side to the other. The virtual antenna group V assumed for transmit antenna TX2_1 is virtual antennas V13, V14, V15, V16, V17, and V18, from one side to the other. The virtual antenna group V assumed for transmit antenna TX2_2 is virtual antennas V19, V20, V21, V22, V23, and V24, from one side to the other.

[0079] Because transmit antennas TX1_1 and TX1_2 are arranged 6d apart, the virtual antenna group V assumed for transmit antenna TX1_1 is offset by 6d from the virtual antenna group V assumed for transmit antenna TX1_2. Furthermore, because transmit antennas TX1_2 and TX2_1 are arranged 4d apart, the virtual antenna group V assumed for transmit antenna TX1_2 is offset by 4d from the virtual antenna group V assumed for transmit antenna TX2_1. Furthermore, because transmit antennas TX2_1 and TX2_2 are arranged 6d apart, the virtual antenna group V assumed for transmit antenna TX2_1 is offset by 6d from the virtual antenna group V assumed for transmit antenna TX2_2.

[0080] Therefore, in such a configuration of antennas TX and RX, Figure 4 As shown, there are two groups of virtual antennas V with overlapping virtual positions. Figure 4 In the figure, for easier viewing, the virtual positions of the multiple virtual antennas V for each transmitting antenna TX are offset in the vertical direction of the paper. In reality, the multiple virtual antennas V are assumed to be at their respective virtual positions on the virtual line VL extending along the reference direction (X direction). Figure 4 In FIG, virtual antennas V having the same position in the left-right direction of the paper form a group of virtual antennas V whose virtual positions overlap.

[0081] Below, if the specific group of virtual antennas V with overlapping virtual positions is represented as (Vn, Vm) (n, m are natural numbers) using the symbols assigned to each individual virtual antenna V, then (V11, V13) and (V12, V14) respectively become the groups of virtual antennas V with overlapping virtual positions.

[0082] The above two groups are sets of groups whose combinations of transmission circuits 3 and reception circuits 4 do not match each other across virtual antennas V. Furthermore, these two groups are sets whose combinations of transmission circuits 3 and reception circuits 4 do not overlap with each other. Therefore, the number of groups whose combinations of transmission circuits 3 and reception circuits 4 do not overlap with other groups is two, satisfying the condition of at least Ns + Nr - 2 groups.

[0083] In addition, as long as the control unit 6 ensures that there are at least Ns+Nr-2 groups of virtual antennas V that do not overlap with the combinations of transmitting circuits 3 and receiving circuits 4 of other groups, the control unit 6 can also additionally assume that the groups that overlap with the combinations of transmitting circuits 3 and receiving circuits 4 of these groups are used for compensation processing.

[0084] In order to control the radar device 1 including the above compensation processing, the processor 6b executes a plurality of commands included in the control program stored in the memory 6a. Thus, the control unit 6 constructs a functional unit for controlling the radar device 1. Specifically, Figure 6 As shown, the control unit 6 includes a signal generating section 60 , an AD converting section 61 , a Fourier transforming section 62 , a comparing section 63 , a compensating section 64 , and an angle acquiring section 65 as functional sections.

[0085] By means of the function of the processor 6b, the control unit 6 controls the radar device 1 in accordance with the radar control method. Figure 7 The control flow shown is executed. This control flow is repeatedly executed during vehicle startup. In addition, each "S" in this control flow represents a plurality of steps executed by a plurality of commands included in the control program.

[0086] First, in S10, the signal generator 60 causes the oscillator 2 to output a transmission signal. Next, in S20, the A / D converter 61 obtains a beat signal from the receiver circuit 4 corresponding to a received signal resulting from the transmission signal transmitted from the transmitting antenna TX to the outside world, reflected by a target object, and received by the receiving antenna RX. In S30, the A / D converter 61 converts the beat signal into a digital signal through an A / D conversion process that samples the beat signal at predetermined time intervals. Next, in S40, the Fourier transform 62 performs an FFT (Fast Fourier Transform) on each chirp of the A / D-converted beat signal. This process allows the Fourier transform 62 to obtain, for each chirp, a frequency spectrum (range spectrum) with a peak at a frequency corresponding to the distance to the target object. The range spectrum is data representing the signal strength for each range bin corresponding to the range resolution.

[0087] The Fourier transform unit 62 then performs an FFT on the range spectrum. Specifically, the Fourier transform unit 62 performs a second FFT on the waveform, which contains the time-series phases in the range bins obtained from the first FFT on the multiple chirps. This yields a frequency spectrum (velocity spectrum) with a peak at a position corresponding to the relative velocity to the target, for each velocity bin. Through this two-dimensional FFT, the Fourier transform unit 62 acquires two-dimensional information (RV map) with peaks at positions corresponding to the distance to the target and the relative velocity of the target.

[0088] Next, in S50, the comparison unit 63 extracts a peak from the RV map. In the following S60, the comparison unit 63 obtains the intensity of the extracted peak. Then, in S70, the comparison unit 63 determines whether the extracted peak is valid. For example, if the intensity of the peak is within the allowable intensity range, the comparison unit 63 determines that the peak is valid. Here, the allowable intensity range is a range where the intensity is above or greater than a specified threshold. If a valid peak is determined to exist, the process transfers to S80.

[0089] In S80 , the compensator 64 obtains the phase error between the transmission circuits 3 and the reception circuits 4 based on the phase of the effective peak in each virtual channel.

[0090] During the phase compensation process, the compensator 64 defines a linear equation based on the phase difference between the peak values ​​in the beat signal for each of the Ns+Nr-2 or more virtual antennas V whose combinations of transmitting circuits 3 and receiving circuits 4 do not overlap with those in other groups. This linear equation defines the relative phase error between the transmitting circuits 3 and the receiving circuits 4 as an unknown. The compensator 64 obtains the solution to this linear equation as the relative phase error. The beat signal is correlated with the received signal, so the phase difference between the peak values ​​in the beat signal is an example of a comparison result of the received signals between the virtual antennas V.

[0091] The acquisition of relative phase error is described in detail below. In the following description, the phase at the peak of the beat signal corresponding to the virtual antenna Vn is denoted as θ Vn (n is a natural number). In the following description, for simplicity, Figure 5 As shown, only two groups, (V11, V13) and (V12, V14), are used as groups that do not overlap with the combinations of the transmission circuit 3 and the reception circuit 4 of other groups.

[0092] In this case, the phase difference θ of the peak associated with (V11, V13) is V11 -θ V13 The phase difference θ of the peak value associated with (V12, V14) can be defined by the relationship shown in formula (1): V12 -θ V14 It can be defined by the relationship shown in formula (2).

[0093] [Formula 1]

[0094] θ V11 -θ V13 =(Θ a +e tx1 +e rx1 )-(Θ a +e tx2 +e rx1 ) …(1)

[0095] [Formula 2]

[0096] θ V12 -θ V14 =(Θ b +e tx1 +e rx2 )-(Θ b +e tx2 +e rx1 ) …(2)

[0097] In addition, in the above formula, Θ a 、Θ b are the phase errors caused by the target object. And, e tx1 is the phase error of the signal generated by the first transmitting circuit 3_1, e tx2 is the phase error of the signal generated by the second transmitting circuit 3_2. rx1 is the phase error of the signal generated in the first receiving circuit 4_1, e rx2 is the phase error of the signal generated in the second receiving circuit 4_2.

[0098] Here, in phase compensation, it is sufficient to consider the relative phase error between the transmission circuits 3 and the relative phase error between the reception circuits 4. Therefore, if the relative phase error of the second transmission circuit 3_2 relative to the first transmission circuit 3_1 and the relative phase error of the second reception circuit 4_2 relative to the first reception circuit 4_1 are considered, it can be set to e tx1 、e rx1 = 0. Therefore, formulas (1) to (2) can be transformed into the following formulas (3) to (4).

[0099] [Formula 3]

[0100] θ V11 -θ V13 =-e tx2 …(3)

[0101] [Formula 4]

[0102] θ V12 -θ V14 =-e tx2 +e rx2 …(4)

[0103] Here, if formulas (3) to (4) are converted into matrix form, the phase difference of each group and the relative phase error satisfy the relationship shown in the following formula (5).

[0104] [Formula 5]

[0105]

[0106] Here, the term on the left side of formula (5) is the phase difference vector Y1 between the overlapping virtual antennas V. The first term on the right side of formula (5) is the coefficient matrix A1, and the second term is the phase error vector X1. The phase difference vector Y1 in formula (5) can be calculated from the phase of the peak in each beat signal. The coefficient matrix A1 is a constant matrix specified by the combination of the transmitting circuit 3 and the receiving circuit 4 of each group of virtual antennas V. Therefore, formula (5) can be used as an equation with e tx2 、e rx2 That is, the compensation unit obtains e as the solution of formula (5) tx2 、e rx2 As the relative phase error of the second transmission circuit 3_2 with respect to the first transmission circuit 3_1, and the relative phase error of the second reception circuit 4_2 with respect to the first reception circuit 4_1.

[0107] In the next S90 , the compensator 64 obtains the amplitude error between the transmission circuits 3 and the reception circuits 4 based on the amplitude of the effective peak in each virtual antenna V.

[0108] In the amplitude compensation process, similar to the phase compensation process, the compensator 64 defines a linear equation based on the amplitude difference between the peak values ​​of the beat signal for each unique group, using the amplitude error between the transmitting circuit 3 and the receiving circuit 4 as an unknown variable. The compensator 64 obtains the solution of this linear equation as the relative amplitude error. The amplitude difference between the peak values ​​of the beat signal is an example of the comparison result of the received signals between the virtual antennas V.

[0109] In the following description, the same set of virtual antennas V as in the above-mentioned phase compensation process is also used in the amplitude compensation process. In the following description, the amplitude at the peak of the beat signal corresponding to the virtual antenna Vn is represented as A. Vn (n is a natural number). In this case, the amplitude difference A of the peak value associated with (V11, V13) is V11 -A V13 The peak amplitude difference A associated with (V12, V14) can be defined by the relationship shown in formula (6): V12 -A V14 It can be defined by the relationship shown in formula (7).

[0110] [Formula 6]

[0111] A V11 -A V13 =(G a +G tx1 +G rx1 )-(G a +G tx2 +G rx1 ) …(6)

[0112] [Formula 7]

[0113] A V12 -A V14 =(G b +G tx1 +G rx2 )-(G b +G tx2 +G rx1 ) …(7)

[0114] In addition, in the above formula, G a , G b are the amplitude errors caused by the target object. And, G tx1 is the amplitude error of the signal generated in the first transmitting circuit 3_1, G tx2 is the amplitude error of the signal generated by the second transmission circuit 3_2. rx1 is the amplitude error of the signal generated in the first receiving circuit 4_1, G rx2 is the amplitude error of the signal generated in the second receiving circuit 4_2.

[0115] Here, similarly to phase compensation, if the relative amplitude error of the second transmission circuit 3_2 with respect to the first transmission circuit 3_1 and the relative amplitude error of the second reception circuit 4_2 with respect to the first reception circuit 4_1 are considered, G can be set to tx1 , G rx1 = 0. Therefore, formulas (6) to (7) can be transformed into the following formulas (8) to (9).

[0116] [Formula 8]

[0117] A V11 -A V13 =-G tx2 …(8)

[0118] [Formula 9]

[0119] A V12 -A V14 =-G tx2 +G rx2 …(9)

[0120] Here, if formulas (8) to (9) are converted into matrix form, the amplitude difference and relative amplitude error of each group satisfy the relationship shown in the following formula (10).

[0121] [Formula 10]

[0122]

[0123] Here, the term on the left side of formula (10) is the amplitude difference vector Y2 between the overlapping virtual antennas V. The first term on the right side of formula (10) is the coefficient matrix A2, and the second term is the amplitude error vector X2. The amplitude difference vector Y2 can be calculated from the peak amplitude in each beat signal. The coefficient matrix A1 is a constant matrix specified by the combination of the transmitting circuit 3 and the receiving circuit 4 of each group of virtual antennas V. That is, the compensation unit 64 obtains G as the solution of formula (10). tx2 , G rx2 As the relative amplitude error of the second transmission circuit 3_2 with respect to the first transmission circuit 3_1, and the relative amplitude error of the second reception circuit 4_2 with respect to the first reception circuit 4_1.

[0124] Next, at S100, the compensator 64 compensates for the phase error between the transmitter circuit 3 and the receiver circuit 4. For example, the compensator 64 stores the acquired relative phase error in the memory 6a as compensation data for use in relative angle acquisition, described later. Furthermore, at S110, the compensator 64 compensates for the relative amplitude error between the transmitter circuit 3 and the receiver circuit 4 by storing the compensation data in the memory 6a.

[0125] On the other hand, if it is determined in S70 that no valid peak exists, the flow proceeds to S120. In S120, the compensator 64 obtains the temperature of each transmitting circuit 3 and each receiving circuit 4 from the temperature sensor 5. Then, in S130, the compensator 64 reads a correction table for phase errors and amplitude errors between the transmitting circuits 3 according to the temperature from the memory 6a.

[0126] Next, in S140, the compensation unit 64 compares the acquired temperature with the correction table to obtain the relative phase error between the transmission circuit 3 and the reception circuit 4. Then, in S150, the compensation unit 64 compares the acquired temperature with the correction table to obtain the relative amplitude error between the transmission circuit 3 and the reception circuit 4. Then, in S160, the compensation unit 64 compensates for the relative phase error between the transmission circuit 3 and the reception circuit 4. Furthermore, in S170, the compensation unit 64 compensates for the relative amplitude error between the transmission circuit 3 and the reception circuit 4.

[0127] In S180, which follows S110 or S170, the angle acquisition unit 65 acquires the relative angle of the target object. Specifically, the angle acquisition unit 65 performs FFT processing on multiple peaks extracted from the beat frequency signal of the compensated reception signal of each virtual antenna V to acquire the phase difference between the virtual antennas V. Since the phase difference between the virtual antennas V is correlated with the relative angle of the target object, the angle acquisition unit 65 converts the acquired phase difference into a relative angle to acquire the relative angle.

[0128] According to this first embodiment, at least one of the phase difference and the amplitude difference between different transmitting circuits 3 and at least one of the phase difference and the amplitude difference between different receiving circuits 4 can be compensated based on the comparison results of the received signals of the virtual antennas V in the unique group of at least Ns+Nr-2 groups. Therefore, in addition to the errors between the different receiving circuits 4, the error compensation processing between the different transmitting circuits 3 can also be performed. Moreover, by configuring at least one of the transmitting antenna TX and the receiving antenna RX at unequal intervals, the opening length of the virtual antenna can be increased compared to the case where they are configured at equal intervals. Specifically, in this embodiment, the transmitting antenna TX is configured at unequal intervals of 4d and 6d, and the opening length is increased compared to the case where it is configured at equal intervals of a smaller interval of 4d. The opening length here is the distance from one end to the other end of the virtual antenna V, which is Figure 4 The distance from the virtual antenna V1 to the virtual antenna V24 is shown. The opening length in this embodiment is 21d. Therefore, both compensation accuracy and spatial resolution can be achieved.

[0129] (Second embodiment)

[0130] like Figures 8 to 11 As shown, the second embodiment is a modification of the first embodiment. In the second embodiment, the transmitting antenna TX and the receiving antenna RX are arranged two-dimensionally.

[0131] As an example, assume that a radar device 1 is equipped with 12 transmitting antennas TX and 16 receiving antennas RX. In this example, the number of transmitting circuits 3 is Ns = 4, and the number of receiving circuits 4 is Nr = 4. In this case, Figure 8 As shown, the number of channels in one transmitting circuit 3 is at least 3, and the number of channels in one receiving circuit 4 is at least 4. Hereinafter, the four transmitting circuits 3 may be categorized as a first transmitting circuit 3_1, a second transmitting circuit 3_2, a third transmitting circuit 3_3, and a fourth transmitting circuit 3_4. Furthermore, the four receiving circuits 4 may be categorized as a first receiving circuit 4_1, a second receiving circuit 4_2, a third receiving circuit 4_3, and a fourth receiving circuit 4_4.

[0132] In this embodiment, each circuit is also mounted on multiple circuit chips C. Specifically, the first transmitting circuit 3_1 and the first receiving circuit 4_1 are mounted on the same first circuit chip C1. Furthermore, the second transmitting circuit 3_2 and the second receiving circuit 4_2 are mounted on the same second circuit chip C2. Furthermore, the third transmitting circuit 3_3 and the third receiving circuit 4_3 are mounted on the same third circuit chip C3. Furthermore, the fourth transmitting circuit 3_4 and the fourth receiving circuit 4_4 are mounted on the same fourth circuit chip C4. Furthermore, the wiring lengths of all traces Wt between the transmitting antenna TX and the corresponding transmitting circuit 3 are substantially the same. Furthermore, the wiring lengths of all traces Wr between the receiving antenna RX and the corresponding receiving circuit 4 are substantially the same.

[0133] In the following, the 12 transmit antennas TX and the 16 receive antennas RX are sometimes denoted by different symbols to distinguish them. Specifically, the three transmit antennas TX connected to the first transmit circuit 3_1 are referred to as transmit antennas TX4, TX5, and TX6, and the three transmit antennas TX connected to the second transmit circuit 3_2 are referred to as transmit antennas TX1, TX2, and TX3. Furthermore, the three transmit antennas TX connected to the third transmit circuit 3_3 are referred to as transmit antennas TX7, TX8, and TX9, and the three transmit antennas TX connected to the fourth transmit circuit 3_4 are referred to as transmit antennas TX10, TX11, and TX12.

[0134] Furthermore, the four receiving antennas RX connected to the first receiving circuit 4_1 are designated as receiving antennas RX5, RX6, RX7, and RX8, and the four receiving antennas RX connected to the second receiving circuit 4_2 are designated as receiving antennas RX1, RX2, RX3, and RX4. Furthermore, the four receiving antennas RX connected to the third receiving circuit 4_3 are designated as receiving antennas RX9, RX10, RX11, and RX12, and the four receiving antennas RX connected to the fourth receiving circuit 4_4 are designated as receiving antennas RX13, RX14, RX15, and RX16.

[0135] The above transmitting antenna TX and receiving antenna RX are arranged two-dimensionally. Figure 9As shown, multiple transmitting antennas TX are arranged in four columns arranged in the X direction and spaced apart in the Y direction. Of the four columns arranged in the X direction, two transmitting antennas TX are arranged in each of the first, second, and fourth columns from the origin. Furthermore, of the four columns arranged in the X direction, six transmitting antennas TX are arranged in the third column from the origin. Here, let the interval of one scale mark in the X direction be d, and the interval of one scale mark in the Y direction be s. Transmitting antennas TX12, TX10, and TX9 are arranged at equal intervals with an interval of d. Furthermore, transmitting antennas TX5, TX4, and TX3 are also arranged at equal intervals with an interval of d. Meanwhile, transmitting antenna TX9 is arranged at an interval of 20d from transmitting antenna TX5. That is, in this third column, the transmitting antennas TX are arranged at unequal intervals in the X direction.

[0136] Furthermore, multiple receive antennas RX are arranged in two rows arranged in the X direction, spaced apart in the Y direction. Eight receive antennas TX are arranged in each of the two rows arranged in the X direction. Within each row, the receive antennas RX are arranged at equal intervals in the X direction. Furthermore, in the two rows arranged in the X direction, the first row from the origin is arranged at the same position in the Y direction as the first row from the origin of the transmit antennas TX. Furthermore, in the two rows arranged in the X direction, the second row from the origin is arranged at the same position in the Y direction as the fourth row from the origin of the transmit antennas TX.

[0137] For each of the 12 transmit antennas TX, the number of virtual antennas V is assumed to be the same as the number of receive antennas RX, that is, 16. Therefore, a total of 192 virtual antennas V are assumed. Specifically, the 192 virtual antennas V are assumed to be Figure 10 and Figure 11 Configuration shown.

[0138] Hereinafter, among the 16 virtual antennas V assumed for a specific transmitting antenna TXa, the virtual antenna V corresponding to a specific receiving antenna RXb (a, b are natural numbers) is expressed as Vc (c = (a-1) × 16 + b). Figure 10 In order to avoid cumbersomeness, "V" is omitted.

[0139] like Figure 10 and Figure 11As shown, there are 24 groups of virtual antennas V with overlapping virtual positions. Of these, there are 13 unique groups that do not overlap with the combinations of transmit circuits 3 and receive circuits 4 in other groups. For example, (V2, V85), (V9, V88), (V10, V93), (V12, V97), (V16, V86), (V60, V129), (V64, V133), (V76, V145), (V80, V149), (V95, V97), (V98, V165), (V105, V168), and (V106, V173) can be assumed to be unique groups. The compensator 64, described later, performs compensation processing based on the received signals acquired from each of the virtual antennas V in at least six of these groups.

[0140] Furthermore, the virtual antenna V pairs used in the compensation process can be assumed to be groups other than the above, as long as they do not overlap with the transmission circuit 3 and reception circuit 4 combinations of other groups. For example, the transmission circuit 3 and reception circuit 4 combinations of (V3, V86) and (V4, V87) overlap with those of (V2, V85), but do not overlap with other groups. Therefore, assuming (V3, V86) or (V4, V87) as one of the 13 groups is equivalent to assuming (V2, V85).

[0141] Furthermore, when there are a large number of antennas TX and RX as described above, the configuration of the antennas TX and RX can be determined using a genetic algorithm. For example, characteristics of the current generation generated by the genetic algorithm can be evaluated using overlap efficiency, rank, wiring efficiency, field of view (FOV), and separation angle. Overlap efficiency is a parameter obtained by dividing the number of channels reduced due to virtual position overlap by the full rank, and is preferably large. Rank is a predetermined parameter. Wiring efficiency is a parameter corresponding to the variance of antenna coordinates input to the same circuit, and is preferably small. Field of view is a parameter corresponding to the spacing between antennas, and is preferably small. Separation angle is a parameter corresponding to the opening length, and is preferably large.

[0142] (Third embodiment)

[0143] like Figures 12 to 16 As shown, the third embodiment is a modification of the first embodiment.

[0144] The number of transmitting circuits 3 and receiving circuits 4 and the number of transmitting antennas TX and receiving antennas RX in the third embodiment are the same as those in the first embodiment. Therefore, in the following, the circuits 3 and antennas TX and RX are sometimes denoted by the same reference numerals as those in the first embodiment to distinguish them.

[0145] In the radar device 1 of the third embodiment, at least one transmitting antenna TX has a different wiring length from the other transmitting antennas TX. Figure 11In the example shown, the wiring Wt2 of the transmitting antenna TX1_2 connected to the first transmitting circuit 3_1 is longer than the wiring Wt1 of the other transmitting antennas TX. Furthermore, the wiring lengths of the wirings Wr of the receiving antenna RX are all substantially the same.

[0146] In the presence of antennas with different wiring lengths, the transmitting antenna TX and the receiving antenna RX are configured as follows: in a set of groups of virtual antennas in which the virtual positions of the virtual antenna V groups assumed for each transmitting antenna TX overlap and the combinations of the transmitting circuit 3 and the receiving circuit 4 are inconsistent, the number of groups of virtual antennas V in which the combination of the transmitting circuit 3 and the receiving circuit 4 does not overlap with that of other groups, that is, the number of unique groups, is at least Ns+Nr-2 groups.

[0147] Furthermore, the transmitting antenna TX and the receiving antenna RX are arranged so that the total number of groups of virtual antennas V to which at least one of the unique group and the different wiring length group belongs, i.e., the total number of groups to which the transmitting antenna TX and the receiving antenna RX belong, is at least Ns + Nr - 1.

[0148] like Figure 13 As shown, transmit antennas TX1_1, TX1_2, TX2_1, and TX2_2 are arranged in order from one side to the other in the X direction. Transmit antenna TX1_1 and transmit antenna TX1_2 are arranged with a gap of 6d between them. Transmit antenna TX1_2 and transmit antenna TX2_1 are arranged with a gap of 3d between them. Furthermore, transmit antenna TX2_1 and transmit antenna TX2_2 are arranged with a gap of 6d between them.

[0149] Furthermore, the receiving antennas RX1_1 , RX1_2 , RX2_1 , RX2_2 , RX2_3 , and RX1_3 are arranged in this order from one side to the other side in the reference direction at intervals d.

[0150] For each of the transmission antennas TX1_1, TX1_2, TX2_1, and TX2_2, six virtual antennas V, which are the number of reception antennas RX, are assumed. Therefore, a total of 24 virtual antennas V are assumed.

[0151] Here, the multiple virtual antennas V assumed for transmit antenna TX1_1 are virtual antennas V1, V2, V3, V4, V5, and V6, from one side to the other. The multiple virtual antennas V assumed for transmit antenna TX1_2 are virtual antennas V7, V8, V9, V10, V11, and V12, from one side to the other. The virtual antenna group V assumed for transmit antenna TX2_1 is virtual antennas V13, V14, V15, V16, V17, and V18, from one side to the other. The virtual antenna group V assumed for transmit antenna TX2_2 is virtual antennas V19, V20, V21, V22, V23, and V24, from one side to the other.

[0152] Because transmit antennas TX1_1 and TX1_2 are arranged 6d apart, the virtual antenna group V assumed for transmit antenna TX1_1 is offset by 6d from the virtual antenna group V assumed for transmit antenna TX1_2. Furthermore, because transmit antennas TX1_2 and TX2_1 are arranged 3d apart, the virtual antenna group V assumed for transmit antenna TX1_2 is offset by 3d from the virtual antenna group V assumed for transmit antenna TX2_1. Furthermore, because transmit antennas TX2_1 and TX2_2 are arranged 6d apart, the virtual antenna group V assumed for transmit antenna TX2_1 is offset by 6d from the virtual antenna group V assumed for transmit antenna TX2_2.

[0153] Therefore, in such a configuration of antennas TX and RX, Figure 14 As shown, there are three sets of virtual antennas V with overlapping virtual positions. Specifically, (V10, V13), (V11, V14), and (V12, V15) are sets of virtual antennas V with overlapping virtual positions.

[0154] The above three groups are sets in which the combinations of transmission circuits 3 and reception circuits 4 do not match each other across virtual antennas V. Furthermore, these three groups do not overlap with each other in the combinations of transmission circuits 3 and reception circuits 4. Therefore, in this antenna configuration, the number of unique groups is three, satisfying the condition of at least Ns + Nr - 2 groups.

[0155] Furthermore, these three groups each have different wiring lengths. That is, the wiring lengths of virtual antennas V10, V11, and V12 are longer than those of virtual antennas V13, V14, and V15. Therefore, in this antenna configuration, there are only one group of different wiring lengths, satisfying the requirement of at least one group. Furthermore, as described above, there are three groups in this antenna configuration, satisfying the requirement of at least Ns + Nr - 1 groups.

[0156] In this case, the control unit 6 also calculates the phase error and amplitude error corresponding to the wiring length difference of the virtual antenna V during the processes of S80 and S90. Here, the wiring length of the virtual antenna V refers to the total wiring length from the transmitting antenna TX corresponding to the virtual antenna V to the transmitting circuit 3 and the wiring length from the corresponding receiving antenna RX to the receiving circuit 4. Here, since only the wiring Wt2 is longer than the wiring Wt1, and all the wiring Wr of the receiving antenna RX are substantially the same length, the wiring length of the virtual antenna V assumed for the transmitting antenna TX1_2 is longer than the wiring length of the virtual antenna V assumed for the transmitting antenna TX other than the transmitting antenna TX1_2.

[0157] Generally speaking, if Figure 15 As shown, the phase error due to wiring length differences for each virtual antenna V increases linearly with the wiring length difference relative to a reference wiring length Lo (e.g., the shortest wiring length). In other words, the phase error due to wiring length differences is the value obtained by multiplying the wiring length difference by K. Here, the slope K associated with the magnitude of the phase error due to wiring length differences is a temperature parameter that changes with temperature. Specifically, if the wiring length of the virtual antenna V assumed for the transmitting antenna TX1_2 in this embodiment is LA, the slope K can be calculated from the wiring length difference LA - Lo. In this case, the reference wiring length Lo is the wiring length of the virtual antenna V assumed for the transmitting antenna TX other than the transmitting antenna TX1_2.

[0158] Here, the wiring length difference in the virtual antenna V assumed for the pair of the transmitting antenna TXa_b and the receiving antenna RXc_d is represented as L abcd (a, b, c, d are natural numbers.) As described above, the compensation unit 64 uses the three groups (V10, V13), (V11, V14), and (V12, V15) as the groups to which it belongs. abcd The resulting phase error is e abcd , then in Figure 16 In the example shown, the phase difference θ of the peak associated with (V10, V13) V10 -θ V13 The peak phase difference θ associated with (V11, V14) can be defined by the relationship shown in formula (11). V11 -θ V14 The peak phase difference θ associated with (V12, V15) can be defined by the relationship shown in formula (12). V12 -θ V15 It can be defined by the relationship shown in formula (13).

[0159] [Formula 11]

[0160] θ V10 -θV13 =(Θ a +e tx1 +e rx2 +e 1222 )-(Θ a +e tx2 +e rx1 +e 1211 )

[0161] …(11)

[0162] [Formula 12]

[0163] θ V11 -θ V14 =(Θ b +e tx1 +e rx1 +e 1213 )-(Θ b +e tx2 +e rx1 +e 2112 )

[0164] …(12)

[0165] [Formula 13]

[0166] θ V12 -θ V15 =(Θ c +e tx1 +e rx2 +e 1223 )-(Θ c +e tx2 +e rx2 +e 2121 )

[0167] …(13)

[0168] Here, if the phase error e abcd Replace with L abcd ·K, the above formulas (11) to (12) can be transformed into the following formulas (14) to (16).

[0169] [Formula 14]

[0170] θ V10 -θ V13 =-e tx2 +e rx2 +(L 1222 +L 1211 )·K …(14)

[0171] [Formula 15]

[0172] θ V11 -θ V14 =-etx2 +(L 1213 -L 2112 )·K …(15)

[0173] [Formula 16]

[0174] θ V12 -θ V15 =-e tx2 +(L 1223 -L 2121 )·K …(16)

[0175] Converting it into a matrix form, the phase difference and relative phase error of each group satisfy the relationship shown in the following formula (17).

[0176] [Formula 17]

[0177]

[0178] Here, the term on the left side of formula (17) is the phase difference vector Y3 between the overlapping virtual antennas V. The first term on the right side of formula (17) is the coefficient matrix A3, and the second term is the phase error vector X3. The phase difference vector Y3 in formula (17) can be calculated from the phase of the peak in each beat signal. The coefficient matrix A3 is a constant matrix specified by the combination of the transmitting circuit 3, the receiving circuit 4, and the wiring length difference of each group of virtual antennas V. Therefore, formula (17) can be used as an equation with e tx2 、e rx2 , K are unknowns. That is, the compensation unit 64 obtains e as the solution of formula (17) tx2 、e rx2 , K as the relative phase error of the second transmitting circuit 3_2 with respect to the first transmitting circuit 3_1, the relative phase error of the second receiving circuit 4_2 with respect to the first receiving circuit 4_1, and the relative phase error corresponding to the wiring length difference.

[0179] In the amplitude compensation process, similar to the phase compensation process, the compensator 64 defines a linear equation based on the amplitude difference of the beat signal's peak value, using the amplitude error between the transmitting circuits 3 and the receiving circuits 4 as an unknown variable, for each of the Ns+Nr-1 or more virtual antennas V that do not overlap with other combinations of transmitting circuits 3 and receiving circuits 4. The compensator 64 obtains the solution of this linear equation as the amplitude error.

[0180] Similar to the phase error, the amplitude error caused by the wiring length difference relative to the reference wiring length Lo increases linearly with the wiring length difference relative to the reference wiring length. The amount of increase in the amplitude error due to the wiring length difference varies with temperature. In other words, the amplitude error caused by the wiring length difference is the value obtained by multiplying the wiring length difference by the temperature parameter α.

[0181] Assume that the wiring length difference L abcd The amplitude error caused is G abcd , then the amplitude difference A of the peak value related to (V10, V13) V10 -A V13 The peak amplitude difference A related to (V11, V14) can be defined by the relationship shown in formula (18): V11 -A V14 The peak amplitude difference A related to (V12, V15) can be defined by the relationship shown in formula (19): V12 -A V15 It can be defined by the relationship shown in formula (20).

[0182] [Formula 18]

[0183] A V10 -A V13 =(G a +G tx1 +G rx2 +G 1222 )-(G a +G tx2 +G rx1 +G 1211 )

[0184] …(18)

[0185] [Formula 19]

[0186] A V11 -A V14 =(G b +G tx1 +G rx1 +G 1213 )-(G b +G tx2 +G rx1 +G 2112 )

[0187] …(19)

[0188] [Formula 20]

[0189] A V12 -A V15 =(G c +G tx1 +G rx2 +G 1223 )-(G c +G tx2 +G rx2 +G 2121 )

[0190] …(20)

[0191] Here, if the amplitude error G abcd Replace with L abcd ·α, the above formulas (18) to (20) can be transformed into the following formulas (21) to (23).

[0192] [Formula 21]

[0193] A V10 -A V13 =-G tx2 +G rx2 +(L 122 -L 1211 )·α …(21)

[0194] [Formula 22]

[0195] A V11 -A V14 =-G tx2 +(L 1213 -L 2112 )·α …(22)

[0196] [Formula 23]

[0197] A V12 -A V15 =-G tx2 +(L 1223 -L 2121 )·α …(23)

[0198] Here, if formulas (21) to (23) are converted into matrix form, the amplitude difference and relative amplitude error of each group satisfy the relationship shown in the following formula (24).

[0199] [Formula 24]

[0200]

[0201] Here, the term on the left side of formula (24) is the amplitude difference vector Y4 between the overlapping virtual antennas V. The first term on the right side of formula (24) is the coefficient matrix A4, and the second term is the amplitude error vector X2. The amplitude difference vector Y4 can be calculated from the peak amplitude in each beat signal. The coefficient matrix A4 is a constant matrix defined by the combination of the transmitting circuit 3, the receiving circuit 4, and the wiring length of each group of virtual antennas V. That is, the compensation unit 64 obtains G as the solution of formula (28) tx2 , G rx2 , α as the relative amplitude error of the second transmitting circuit 3_2 with respect to the first transmitting circuit 3_1, the relative amplitude error of the second receiving circuit 4_2 with respect to the first receiving circuit 4_1, and the relative amplitude error based on the wiring length.

[0202] According to this third embodiment, based on the comparison results of the received signals between virtual antennas in at least Ns+Nr-1 groups, it is possible to compensate for at least one of the phase difference and amplitude difference between different transmitting circuits, at least one of the phase difference and amplitude difference between different receiving circuits, and at least one of the phase difference and amplitude difference corresponding to the wiring length difference between virtual antennas. Therefore, it is possible to compensate for errors between different transmitting circuits and errors caused by wiring length differences, in addition to errors between different receiving circuits. Furthermore, by arranging at least one of the transmitting and receiving antennas at unequal intervals, the opening length of the virtual antenna can be increased compared to a case where they are arranged at equal intervals. Therefore, it is possible to achieve a balance between compensation accuracy and spatial resolution.

[0203] (Fourth embodiment)

[0204] like Figure 17 As shown, the fourth embodiment is a modification of the second embodiment.

[0205] In the fourth embodiment, the number of circuits 3 and 4, and the number and arrangement of antennas TX and RX are the same as those in the second embodiment. Figure 9 On the other hand, the wiring length of each virtual antenna V is assumed to be Figure 17 That is, at least one of the wiring length from each transmitting circuit 3 to each transmitting antenna TX and the wiring length from each receiving antenna RX to each receiving circuit 4 is defined so that the wiring length of the corresponding virtual antenna V has Figure 17 The relative relationship shown.

[0206] Here, since Ns=4 and Nr=4, the control unit 6 further calculates the phase error and amplitude error between the transmitting circuits 3, the phase error and amplitude error between the receiving circuits 4, and the phase error and amplitude error corresponding to the wiring length difference based on the beat signals of at least seven groups in the group in the processing of S80 and S90.

[0207] (Other embodiments)

[0208] Although a plurality of embodiments have been described above, the present disclosure should not be construed as being limited to these embodiments, and can be applied to various embodiments and combinations within a scope not departing from the gist of the present disclosure.

[0209] In a modified example of the second embodiment, the transmitting antenna TX and the receiving antenna RX may be arranged at unequal intervals. Figure 18 As shown, the transmitting antenna TX and the receiving antenna RX can be arranged two-dimensionally at unequal intervals. Figure 18 In the configuration shown, the virtual antenna V is configured at Figure 19 Virtual location shown.

[0210] In a modified example, the dedicated computer constituting the control unit 6 may be a sensor integrated ECU that centrally controls various sensors mounted on the vehicle. The dedicated computer constituting the control unit 6 may also be an integrated ECU that integrates the vehicle's driving control. The dedicated computer constituting the control unit 6 may also be a determination ECU that determines the driving task in the vehicle's driving control. The dedicated computer constituting the control unit 6 may also be a monitoring ECU that monitors the vehicle's driving control. The dedicated computer constituting the control unit 6 may also be an evaluation ECU that evaluates the vehicle's driving control. The dedicated computer constituting the control unit 6 may also be a navigation ECU that guides the vehicle's driving route. The dedicated computer constituting the control unit 6 may also be a positioner ECU that estimates the vehicle's own state. The dedicated computer constituting the control unit 6 may also be an actuator ECU that controls the vehicle's driving actuators. The dedicated computer constituting the control unit may also be an HCU (Human Machine Interface (HMI) Control Unit) that controls information presentation within the vehicle. The dedicated computer constituting the control unit 6 may also be a computer outside the vehicle, such as an external center or mobile terminal that can communicate with the vehicle.

[0211] In a modified embodiment, the mobile object to which the radar device 1 is applied may be, for example, an autonomous robot capable of transporting goods or collecting information through autonomous or remote driving. Examples of autonomous robots include autonomous vehicles. In addition to the embodiments described so far, the above-described embodiments and modifications may also be implemented as a control device capable of being mounted on a mobile object and having at least one processor 6 b and one memory 6 a, in the form of a processing circuit (e.g., a processing ECU) or a semiconductor device (e.g., a semiconductor chip).

[0212] (Disclosure of technical ideas)

[0213] This specification discloses multiple technical concepts described in the following multiple items. Some items may be described in a multiple-dependent form, where subsequent items selectively reference a previous item. Furthermore, some items may be described in a multiple-dependent form referring to another multiple-dependent form. These items described in multiple-dependent form define multiple technical concepts.

[0214] (Technical Thought 1)

[0215] A radar device comprising: a plurality of transmitting antennas (TX) and a plurality of receiving antennas (RX);

[0216] Ns transmitting circuits (3), which are connected to the transmitting antenna and output a transmitting signal;

[0217] Nr receiving circuits (4), which are connected to the receiving antenna and acquire received signals; and

[0218] a control unit (6) for processing the received signal,

[0219] The Ns and Nr are integers greater than 2,

[0220] At least one of the plurality of transmitting antennas and the plurality of receiving antennas is arranged at unequal intervals, and the plurality of transmitting antennas and the plurality of receiving antennas are arranged so that, among groups of virtual antennas (V) assumed for each of the plurality of receiving antennas according to a phase difference of the received signals between the receiving antennas, the set of groups of virtual antennas whose virtual positions overlap and whose combinations of the transmitting circuits and the receiving circuits do not coincide with each other includes at least Ns+Nr-2 unique groups, wherein the unique groups are groups of virtual antennas whose combinations of the transmitting circuits and the receiving circuits do not overlap with those of other groups.

[0221] The control unit performs compensation processing, which compensates for at least one of the phase difference and amplitude difference between different transmitting circuits and at least one of the phase difference and amplitude difference between different receiving circuits based on the comparison results of the received signals between the virtual antennas in the unique group of at least Ns+Nr-2 groups.

[0222] (Technical Thought 2)

[0223] A radar device comprising:

[0224] Multiple transmit antennas (TX) and multiple receive antennas (RX);

[0225] Ns transmitting circuits (3), which are connected to the transmitting antenna and output a transmitting signal;

[0226] Nr receiving circuits (4), which are connected to the receiving antenna and acquire received signals; and

[0227] a control unit (6) for processing the received signal,

[0228] The Ns and Nr are integers greater than 2,

[0229] At least one of the plurality of transmitting antennas and the plurality of receiving antennas is arranged at unequal intervals,

[0230] And the multiple transmitting antennas and the multiple receiving antennas are configured as follows:

[0231] Among the groups of virtual antennas (V) assumed for each of the transmitting antennas for the plurality of receiving antennas according to the phase difference of the received signals between the receiving antennas, the set of groups of virtual antennas whose virtual positions overlap and whose combinations of the transmitting circuits and the receiving circuits do not coincide with each other includes at least Ns+Nr-2 unique groups, each of which is a group of virtual antennas whose combinations of the transmitting circuits and the receiving circuits do not overlap with those of other groups.

[0232] comprising at least one group of different wiring lengths, wherein the different wiring length group is a group of the virtual antennas whose virtual positions overlap and whose wiring lengths are inconsistent,

[0233] and the total number of belonging groups is at least Ns+Nr-1 groups, and the belonging groups are groups of the virtual antennas belonging to at least one of the unique group and the different wiring length groups,

[0234] The control unit performs compensation processing, which compensates for at least one of the phase difference and amplitude difference corresponding to the wiring length difference between the virtual antennas in the group belonging to at least Ns+Nr-1 groups, at least one of the phase difference and amplitude difference between different transmitting circuits, and at least one of the phase difference and amplitude difference between different receiving circuits based on the comparison result of the received signals between the virtual antennas in the group belonging to at least Ns+Nr-1 groups.

[0235] (Technical Thought 3)

[0236] According to the radar device described in Technical Idea 1 or Technical Idea 2, the control unit also performs the compensation processing using the comparison result of the received signals between the virtual antennas in the group of virtual antennas whose combination of the transmitting circuit and the receiving circuit overlaps with other groups.

[0237] (Technical Thought 4)

[0238] According to the radar device described in any one of the technical ideas 1 to 3,

[0239] A temperature sensor (5) is also provided, which detects the temperature of the transmitting circuit and the receiving circuit.

[0240] The control unit determines whether the received signal is effective for the compensation process,

[0241] When it is determined that the received signal is not valid for the compensation process, the control unit executes the compensation process based on the temperatures of the transmitting circuit and the receiving circuit.

[0242] (Technical Thought 5)

[0243] According to the radar device described in any one of the technical ideas 1 to 4,

[0244] The transmitting antenna and the receiving antenna are arranged one-dimensionally.

[0245] (Technical Thought 6)

[0246] According to the radar device described in any one of Technical Concepts 1 to 4, at least one of the transmitting antenna and the receiving antenna is arranged two-dimensionally.

Claims

1. A radar device, characterized in that: have: Multiple transmit antennas (TX) and multiple receive antennas (RX); Ns transmitting circuits (3), which are connected to the transmitting antenna and output a transmitting signal; Nr receiving circuits (4), which are connected to the receiving antenna and acquire received signals; and a control unit (6) for processing the received signal, The Ns and Nr are integers greater than 2, At least one of the plurality of transmitting antennas and the plurality of receiving antennas is arranged at unequal intervals, and the plurality of transmitting antennas and the plurality of receiving antennas are arranged so that, among the groups of virtual antennas (V) assumed for each of the plurality of receiving antennas according to the phase difference of the received signals between the receiving antennas, the set of groups of virtual antennas whose virtual positions overlap and whose combinations of the transmitting circuits and the receiving circuits do not coincide with each other includes at least Ns+Nr-2 unique groups, wherein the unique groups are groups of virtual antennas whose combinations of the transmitting circuits and the receiving circuits do not overlap with those of other groups. The control unit performs compensation processing, which compensates for at least one of the phase difference and amplitude difference between different transmitting circuits and at least one of the phase difference and amplitude difference between different receiving circuits based on the comparison results of the received signals between the virtual antennas in the unique group of at least Ns+Nr-2 groups.

2. A radar device, characterized in that: have: Multiple transmit antennas (TX) and multiple receive antennas (RX); Ns transmitting circuits (3), which are connected to the transmitting antenna and output a transmitting signal; Nr receiving circuits (4), which are connected to the receiving antenna and acquire received signals; and a control unit (6) for processing the received signal, The Ns and Nr are integers greater than 2, At least one of the plurality of transmitting antennas and the plurality of receiving antennas is arranged at unequal intervals, And the multiple transmitting antennas and the multiple receiving antennas are configured as follows: Among the groups of virtual antennas (V) assumed for each of the transmitting antennas for the plurality of receiving antennas according to the phase difference of the received signals between the receiving antennas, the set of groups of virtual antennas whose virtual positions overlap and whose combinations of the transmitting circuits and the receiving circuits do not coincide with each other includes at least Ns+Nr-2 unique groups, each of which is a group of virtual antennas whose combinations of the transmitting circuits and the receiving circuits do not overlap with those of other groups; comprising at least one group of different wiring lengths, wherein the different wiring length group is a group of the virtual antennas whose virtual positions overlap and whose wiring lengths are inconsistent; and the total number of belonging groups is at least Ns+Nr-1 groups, and the belonging groups are groups of the virtual antennas belonging to at least one of the unique group and the different wiring length groups, The control unit performs compensation processing, which compensates for at least one of the phase difference and amplitude difference corresponding to the wiring length difference between the virtual antennas in the group belonging to at least Ns+Nr-1 groups, at least one of the phase difference and amplitude difference between different transmitting circuits, and at least one of the phase difference and amplitude difference between different receiving circuits based on the comparison result of the received signals between the virtual antennas in the group belonging to at least Ns+Nr-1 groups.

3. The radar device according to claim 1 or claim 2, characterized in that The control unit further executes the compensation process using the comparison result of the received signals between the virtual antennas in the group of virtual antennas in which the combination of the transmission circuit and the reception circuit overlaps with another group.

4. The radar device according to claim 1 or claim 2, characterized in that A temperature sensor (5) is also provided, which detects the temperature of the transmitting circuit and the receiving circuit. The control unit determines whether the received signal is effective for the compensation process, When it is determined that the received signal is not valid for the compensation process, the control unit executes the compensation process based on the temperatures of the transmitting circuit and the receiving circuit.

5. The radar device according to claim 1 or claim 2, characterized in that: The transmitting antenna and the receiving antenna are arranged one-dimensionally.

6. The radar device according to claim 1 or claim 2, characterized in that: At least one of the transmitting antenna and the receiving antenna is arranged two-dimensionally.

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