radar equipment

Abstract

To provide a radar device with which it is possible to improve compensation accuracy.SOLUTION: The radar device comprises: a plurality of transmission antennas arranged at equal intervals and a plurality of reception antennas arranged at equal intervals; Ns transmission circuits; Nr reception circuits; and a control unit. Ns and Nr each represent an integer 2 or greater. The plurality of transmission antennas and the plurality of reception antennas are arranged so that at least specific Ns+Nr-2 sets of virtual antennas where combinations of the transmission circuits and the reception circuits do not overlap other sets are included, in an aggregate of virtual antenna sets in which virtual positions overlap between virtual antenna groups and combinations of the transmission circuits and the reception circuits do not match. 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 results of comparison of reception signals between virtual antennas in at least Ns+Nr-2 specific sets.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] This disclosure relates to radar technology. [Background technology]

[0002] Patent Document 1 discloses a radar device including multiple receiving antennas provided in multiple receiving circuits, first and second transmitting antennas, and a phase compensation unit. The first and second transmitting antennas are provided at a predetermined distance from the receiving antenna so that the receiving antennas are virtually overlapping. The phase compensation unit compensates for the phase difference between the receiving circuits of the reflected waves of the transmission waves transmitted from the first and second transmitting antennas based on a comparison result of the received signals received by each of the virtually overlapping receiving antennas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-60732 Summary of the Invention [Problem to be solved by the invention]

[0004] In the radar device of Patent Document 1, only the phase difference between different receiving circuits can be compensated for. However, since there are other factors that cause errors in different received signals besides differences in the receiving circuits, it is difficult to ensure compensation accuracy. Furthermore, in the radar device of Patent Document 1, the aperture length is shortened by the amount of virtual overlap between the receiving antennas, which reduces spatial resolution. Therefore, it is difficult for the radar device of Patent Document 1 to achieve both compensation accuracy and spatial resolution.

[0005] An object of the present disclosure is to provide a radar device that can achieve both high compensation accuracy and high spatial resolution. [Means for solving the problem]

[0006] The technical means of the present disclosure for solving the problems will be described below. Note that the claims and the reference symbols in parentheses in this section indicate the correspondence with the specific means described in the embodiments described later in detail, and do not limit the technical scope of the present disclosure.

[0007] A first aspect of the present disclosure is a radio communication system including a plurality of transmit antennas (TX) and a plurality of receive antennas (RX); Ns transmitting circuits (3) connected to the transmitting antenna and outputting a transmitting signal; Nr receiving circuits (4) connected to the receiving antennas and configured to acquire received signals; a control unit (6) for processing the received signal; Ns and Nr are each an integer of 2 or more, The plurality of transmitting antennas and the plurality of receiving antennas are at least one of the sets of virtual antennas is arranged at unequal intervals, and among a set of sets of virtual antennas whose virtual positions overlap among groups of virtual antennas (V) assumed for each transmitting antenna for a plurality of receiving antennas in accordance with a phase difference of the received signals between the receiving antennas and whose combinations of transmitting circuits and receiving circuits do not match, at least Ns+Nr-2 sets of unique sets of virtual antennas whose combinations of transmitting circuits and receiving circuits do not overlap with other sets are arranged; The control unit Comparison results for received signals between virtual antennas in at least Ns+Nr-2 unique sets The phase difference of the peak in the beat signal is Based on this, the phase between different transmission circuits Difference and , the phase between different receiving circuits Difference and , compensation process to compensate for and a compensation process for compensating for amplitude differences between different transmitting circuits and amplitude differences between different receiving circuits based on the amplitude differences of peaks in the beat signal, which are the comparison results. This is a radar device that executes the above.

[0008] According to this first aspect, at least one of phase differences and amplitude differences between different transmitter circuits and at least one of phase differences and amplitude differences between different receiver circuits can be compensated for based on the comparison results of the received signals between virtual antennas in at least Ns+Nr-2 unique pairs. Therefore, it is possible to compensate for errors not only between different receiver circuits but also between different transmitter circuits. Furthermore, by arranging at least one of the transmitter antennas and the receiver antennas at uneven intervals, the aperture length of the virtual antenna can be longer than when the antennas are arranged at equal intervals. Therefore, it is possible to achieve both compensation accuracy and spatial resolution.

[0009] A second aspect of the present disclosure provides a wireless communication system including a plurality of transmitting antennas (TX) and a plurality of receiving antennas (RX); Ns transmitting circuits (3) connected to the transmitting antenna and outputting a transmitting signal; Nr receiving circuits (4) connected to the receiving antennas and configured to acquire received signals; a control unit (6) for processing the received signal; Ns and Nr are each an integer of 2 or more, The plurality of transmitting antennas and the plurality of receiving antennas are At least one of them is arranged at uneven intervals, Among a set of virtual antenna pairs whose virtual positions overlap among groups of virtual antennas (V) assumed for each transmitting antenna for a plurality of receiving antennas in accordance with a phase difference of received signals between the receiving antennas and whose combinations of transmitting circuits and receiving circuits do not match, at least Ns+Nr-2 unique pairs of virtual antenna pairs whose combinations of transmitting circuits and receiving circuits do not overlap with other pairs are included; At least one different wiring length pair is included, which is a pair of virtual antennas whose virtual positions overlap and whose wiring lengths do not match, and the total number of belonging groups, which are groups of virtual antennas belonging to at least one of the specific group and the different wiring length group, is at least Ns+Nr-1 groups; The control unit Comparison results for received signals between virtual antennas in at least Ns+Nr-1 groups The phase difference of the peak in the beat signal isBased on this, the phase according to the difference in wiring length between the virtual antennas is calculated. Difference and , the phase between different transmission circuits Difference and , the phase between different receiving circuits Difference and , compensation process to compensate for and a compensation process for compensating for an amplitude difference corresponding to a difference in wiring length between the virtual antennas, an amplitude difference between different transmitting circuits, and an amplitude difference between different receiving circuits based on the amplitude difference of the peaks in the beat signal, which is the comparison result. This is a radar device that executes the above.

[0010] According to this second aspect, at least one of a phase difference and an amplitude difference between different transmitter circuits, a phase difference and an amplitude difference between different receiver circuits, and a phase difference and an amplitude difference corresponding to a difference in wiring length between virtual antennas can be compensated for based on a comparison result between the received signals of at least Ns+Nr-1 groups. Therefore, it is possible to compensate for errors between different transmitter circuits and errors due to differences in wiring length, in addition to errors between different receiver circuits. Furthermore, by arranging at least one of the transmitter antennas and the receiver antennas at uneven intervals, the aperture length of the virtual antenna can be larger than when the antennas are arranged at equal intervals. Therefore, it is possible to achieve both compensation accuracy and spatial resolution. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating a basic configuration of a radar device according to a first embodiment. [Figure 2] 3A and 3B are schematic diagrams showing examples of combinations of a transmitter circuit and a transmitter antenna, and a receiver circuit and a receiver antenna in the first embodiment. [Figure 3] FIG. 2 is a schematic diagram showing an example of the arrangement of transmitting antennas and receiving antennas in the first embodiment. [Figure 4] FIG. 2 is a schematic diagram showing a virtual antenna assumed in the first embodiment. [Figure 5] 10 is a table showing an example of a set of virtual antennas used in compensation processing. [Figure 6] FIG. 2 is a block diagram showing the functional configuration of a control unit according to the first embodiment. [Figure 7] 4 is a flowchart showing a control flow according to the first embodiment. [Figure 8]10A and 10B are schematic diagrams showing examples of combinations of a transmitter circuit and a transmitter antenna, and a receiver circuit and a receiver antenna in a second embodiment. [Figure 9] FIG. 10 is a schematic diagram showing an example of the arrangement of transmitting antennas and receiving antennas in the second embodiment. [Figure 10] FIG. 10 is a schematic diagram showing a virtual antenna assumed in the second embodiment. [Figure 11] FIG. 1 is a schematic diagram showing overlapping antennas. [Figure 12] 10A and 10B are schematic diagrams showing examples of combinations of a transmitter circuit and a transmitter antenna, and a receiver circuit and a receiver antenna in a third embodiment. [Figure 13] FIG. 11 is a schematic diagram showing an example of the arrangement of transmitting antennas and receiving antennas in a third embodiment. [Figure 14] FIG. 10 is a schematic diagram showing a virtual antenna assumed in the third embodiment. [Figure 15] 10 is a graph showing the relationship between wiring length difference and phase error. [Figure 16] 10 is a table showing an example of a set of virtual antennas used in compensation processing. [Figure 17] 10 is a graph showing the relative relationship of wiring lengths in the fourth embodiment. [Figure 18] FIG. 10 is a schematic diagram showing an example of the arrangement of transmitting antennas and receiving antennas in another embodiment. [Figure 19] FIG. 10 is a schematic diagram showing the virtual position of a virtual antenna in another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, multiple embodiments of the present disclosure will be described with reference to the drawings. Note that corresponding components in each embodiment are designated by the same reference numerals, and redundant description may be omitted. Furthermore, when only a portion of the configuration is described in each embodiment, the configuration of another previously described embodiment may be applied to the remaining portions of the configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of multiple embodiments may be partially combined together even if not explicitly stated, provided that there is no particular problem with the combination.

[0013] (First embodiment) A first embodiment of the present disclosure will be described with reference to Figures 1 to 7. A radar device 1 is mounted on a moving body such as a vehicle. The radar device 1 transmits a transmission signal, receives the transmission signal reflected by an object as a received signal, and detects, as target information, the distance to a target that is the object that reflected the transmission signal, the relative speed to the target, the direction of the target, etc.

[0014] The target information output from the radar device 1 is input to an in-vehicle ECU (Electronic Control Unit) via an in-vehicle network such as a Control Area Network (CAN) (registered trademark) or Ethernet (registered trademark). The in-vehicle ECU executes various processes for automatic driving of the vehicle and advanced driving assistance based on the acquired target information of each target.

[0015] Processing based on target information includes, for example, collision avoidance processing, warning processing, etc. Collision avoidance processing is processing for controlling the vehicle to avoid collision with a target by controlling the brake system, steering system, etc. based on the target information of each target. Warning processing is processing for warning the driver of the possibility of collision with a target based on the target information of each target.

[0016] 1, the 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. The radar device 1 is a so-called MIMO (Multiple-Input-Multiple-Output) radar that transmits transmission signals from multiple transmission antennas TX to artificially increase the number of reception antennas RX beyond the actual number.

[0017] The oscillator 2 receives a control signal from the control unit 6 and generates a modulated signal modulated in response to the control signal. The modulated signal is, for example, a so-called chirp signal whose frequency changes over time. The modulated signal is distributed and output to each channel of the transmitting circuit 3 and the receiving circuit 4. In the following, the modulated signal output from the oscillator 2 to the transmitting circuit 3 is referred to as a transmission signal. Also, the modulated signal output from the oscillator 2 to the receiving circuit 4 is referred to as a local signal.

[0018] The transmitting circuit 3 and the receiving circuit 4 are each mainly composed of a semiconductor integrated circuit device such as an MMIC (Monolithic Microwave Integrated Circuit). The transmitting circuit 3 is connected to a transmitting antenna TX and outputs a transmitting signal to the transmitting antenna TX. If the number of transmitting circuits 3 mounted in one radar device 1 is Ns, Ns is an integer equal to or greater than 2. The transmitting circuit 3 is provided with amplifiers 30 in the same number as the connected transmitting antennas TX. The amplifiers 30 amplify the transmitting signals output from the oscillator 2 and output the signals to the corresponding transmitting antennas TX.

[0019] The transmitting antenna TX converts an electrical signal, which is a transmission signal supplied from the oscillator 2, 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 having multiple flat antenna elements. The antenna elements are arranged on the surface opposite to the ground plane of a dielectric substrate having a ground plane on one surface, so as to face the ground plane. The multiple antenna elements are connected, for example, in series, by a feeder line that supplies the electrical signal.

[0020] The receiving antenna RX receives, as a received signal, a radio wave signal including a transmission signal reflected by a target in the external world as a reflecting object. The receiving antenna RX is connected to a corresponding receiving circuit 4. The arrangement of the transmitting antenna TX and the receiving antenna RX will be described later.

[0021] The receiving antenna RX converts the received signal as a radio wave signal into an electrical signal and outputs it to the corresponding receiving circuit 4. The receiving antenna RX is, for example, a patch antenna in the same manner as the transmitting antenna TX, in which at least one antenna element is connected in series by a feeder line.

[0022] The receiving circuit 4 is connected to the receiving antenna RX and acquires the received signal received by the receiving antenna RX. If the number of receiving circuits 4 mounted in one radar device 1 is Nr, Nr is an integer equal to or greater than 2. The receiving circuit 4 includes amplifiers 40 and signal mixers 41, the number of which is the same as the number of connected receiving antennas RX.

[0023] The amplifier 40 amplifies the received signal received by the receiving antenna and outputs it to the signal mixer 41. The signal mixer 41 generates a beat signal by mixing the local signal from the oscillator 2 with the received signal. The generated beat signal becomes an interference signal that represents the frequency difference between the received signal and the local signal. The beat signal is filtered 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, and is then output to the control unit 6 as signal data related to the received signal.

[0024] 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 according to the resistance value of the thermistor. The temperature sensor 5 detects temperature information of each of the transmission circuits 3 and the reception circuits 4, and outputs the information to the control unit 6.

[0025] 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) specialized for controlling the radar device 1.

[0026] The dedicated computer constituting the control unit 6 has at least one memory 6a and one processor 6b. The memory 6a is at least one type of non-transitory tangible storage medium, such as a semiconductor memory, a magnetic medium, or an optical medium, that non-temporarily stores computer-readable programs and data. Here, "storage" may refer to accumulation in which data is retained even when the sensor system is turned on or off, or temporary storage in which data is erased when the sensor system is turned off. The processor 6b may include at least one type of core selected from a central processing unit (CPU), a graphics processing unit (GPU), a reduced instruction set computer (RISC)-CPU, a data flow processor (DFP), and a graph streaming processor (GSP). Alternatively, the processor 6b may be at least one of a digital circuit and an analog circuit. Here, the digital circuit is at least one of, for example, 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), etc. Furthermore, such a digital circuit may have a memory 6a that stores a program.

[0027] The control unit 6 processes the beat signals output from the receiver circuits 4 to perform angle measurement processing to calculate the angle of a reflecting object relative to the radar device 1. The radar device 1 ensures a relatively high angle resolution by using a MIMO system to pseudo-ensure that the number of receiver antennas RX is greater than the actual number. In addition, the control unit 6 performs compensation processing to compensate for signal phase differences and amplitude differences that occur between different transmitter circuits 3 and different receiver circuits 4, thereby ensuring a relatively high angle measurement accuracy.

[0028] For the above compensation processing, the transmitting antennas TX and receiving antennas RX are mounted in a specified arrangement. The arrangement of the transmitting antennas TX and receiving antennas RX will be explained below with reference to specific examples shown in Figs.

[0029] With multiple transmitting antennas TX and multiple receiving antennas RX, multiple virtual antennas V corresponding to the phase differences of the received signals between the receiving antennas RX are assumed for each transmitting antenna TX. The virtual position of each virtual antenna V is defined by the relative position of the corresponding transmitting antenna TX with respect to the other transmitting antennas TX and the relative position of the corresponding receiving antenna RX with respect to the other receiving antennas RX.

[0030] The transmitting antennas TX and receiving antennas RX are arranged so that the number of unique pairs of virtual antennas V, which are pairs of virtual antennas V whose combinations of transmitting circuits 3 and receiving circuits 4 do not overlap with other pairs, among the set of pairs of virtual antennas whose virtual positions overlap among the groups of virtual antennas V assumed for each transmitting antenna TX and whose combinations of transmitting circuits 3 and receiving circuits 4 do not match, is at least Ns+Nr-2 pairs.

[0031] As an example, assume that the radar device 1 is equipped with four transmitting antennas TX and six receiving antennas RX. Furthermore, 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, as shown in FIG. 2, 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 of the transmitting circuits 3 is referred to as a first transmitting circuit 3_1, and the other as a second transmitting circuit 3_2. Furthermore, one of the receiving circuits 4 is referred to as a first receiving circuit 4_1, and the other as a second receiving circuit 4_2. In this embodiment, each circuit is mounted on a plurality of 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. The second transmitting circuit 3_2 and the second receiving circuit 4_2 are mounted on the same second circuit chip C2. It is assumed that the wiring lengths Wt between the transmitting antennas TX and the corresponding transmitting circuits 3 are all substantially the same. Also, the wiring lengths of the wirings Wr between the receiving antennas RX and the corresponding receiving circuits 4 are all assumed to be substantially the same.

[0032] Furthermore, in the following description, the four transmitting antennas TX and six receiving antennas RX may be distinguished by assigning different reference symbols to them. Specifically, the two transmitting antennas TX connected to the first transmitting circuit 3_1 are referred to as transmitting antennas TX1_1 and TX1_2, and the two transmitting antennas TX connected to the second transmitting circuit 3_2 are referred to as transmitting antennas TX2_1 and TX2_2. The three receiving antennas RX connected to the first receiving circuit 4_1 are referred to as receiving antennas RX1_1, RX1_2, and RX1_3, and the three receiving antennas RX connected to the second receiving circuit 4_2 are referred to as receiving antennas RX2_1, RX2_2, and RX2_3.

[0033] In this case, the transmitting antennas TX and receiving antennas RX are arranged so that the number of pairs of transmitting circuits 3 and receiving circuits 4 that do not overlap with other pairs in the above-mentioned group of virtual antennas V is at least Ns+Nr-2 pairs, i.e., 2 pairs. In this embodiment, the transmitting antennas TX and receiving antennas RX are each arranged one-dimensionally. Here, "arranged one-dimensionally" means that they are arranged side by side along one reference direction.

[0034] In the example shown in Fig. 3, transmitting antennas TX1_1, TX1_2, TX2_1, and TX2_2 are arranged in this order from one side to the other in the X direction, which is the reference direction. The transmitting antennas TX1_1 and TX1_2 are arranged with a distance of 6d between them. The transmitting antennas TX1_2 and TX2_1 are arranged with a distance of 4d between them. And the transmitting antennas TX2_1 and TX2_2 are arranged with a distance of 6d between them.

[0035] 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.

[0036] The number of virtual antennas V is assumed to be the same as the number of receiving antennas RX, that is, six, for each of the transmitting antennas TX1_1, TX1_2, TX2_1, and TX2_2. Therefore, a total of 24 virtual antennas V are assumed.

[0037] Here, the multiple virtual antennas V assumed for the transmitting antenna TX1_1 are, from one side to the other, virtual antennas V1, V2, V3, V4, V5, and V6. The multiple virtual antennas V assumed for the transmitting antenna TX1_2 are, from one side to the other, virtual antennas V7, V8, V9, V10, V11, and V12. The group of virtual antennas V assumed for the transmitting antenna TX2_1 are, from one side to the other, virtual antennas V13, V14, V15, V16, V17, and V18. The group of virtual antennas V assumed for the transmitting antenna TX2_2 are, from one side to the other, virtual antennas V19, V20, V21, V22, V23, and V24.

[0038] Because the transmitting antennas TX1_1 and TX1_2 are arranged at an interval of 6d, the virtual antenna V assumed for the transmitting antenna TX1_1 is at a virtual position relatively shifted by 6d from the virtual antenna V assumed for the transmitting antenna TX1_2. Furthermore, because the transmitting antennas TX1_2 and TX2_1 are arranged at an interval of 4d, the virtual antenna V assumed for the transmitting antenna TX1_2 is at a virtual position relatively shifted by 4d from the virtual antenna V assumed for the transmitting antenna TX2_1. Furthermore, because the transmitting antennas TX2_1 and TX2_2 are arranged at an interval of 6d, the virtual antenna V assumed for the transmitting antenna TX2_1 is at a virtual position relatively shifted by 6d from the virtual antenna V assumed for the transmitting antenna TX2_2.

[0039] Therefore, in such an arrangement of antennas TX and RX, there are two sets of virtual antennas V whose virtual positions overlap, as shown in Fig. 4. Note that in Fig. 4, for ease of viewing, the virtual positions of the multiple virtual antennas V for each transmitting antenna TX are depicted shifted in the vertical direction on the page. In reality, the virtual positions of the multiple virtual antennas V are assumed to be on a virtual line VL extending in the reference direction (X direction). In other words, virtual antennas V that are at the same horizontal position on the page in Fig. 4 are sets of virtual antennas V whose virtual positions overlap.

[0040] In the following, if a specific pair of virtual antennas V with overlapping virtual positions is expressed as (Vn, Vm) using the symbols assigned to each individual virtual antenna V (n and m are natural numbers), then (V11, V13) and (V12, V14) are pairs of virtual antennas V with overlapping virtual positions, respectively.

[0041] The above two sets are sets of sets in which the combinations of the transmitting circuits 3 and the receiving circuits 4 do not match for the virtual antennas V. Furthermore, these two sets are sets in which the combinations of the transmitting circuits 3 and the receiving circuits 4 do not overlap with each other. Therefore, the number of sets in which the combinations of the transmitting circuits 3 and the receiving circuits 4 do not overlap with other sets is two, which satisfies the condition of at least Ns+Nr-2 sets.

[0042] Furthermore, if at least Ns+Nr-2 pairs of virtual antennas V whose combinations of transmitting circuits 3 and receiving circuits 4 do not overlap with other pairs are secured, the control unit 6 may additionally consider pairs whose combinations of transmitting circuits 3 and receiving circuits 4 overlap with those pairs as pairs to be used for compensation processing.

[0043] To control the radar device 1, including the compensation process described above, the processor 6b executes a plurality of instructions included in a control program stored in the memory 6a. This causes the control unit 6 to implement functional units for controlling the radar device 1. Specifically, as shown in Fig. 6, the control unit 6 implements a signal generating unit 60, an AD converting unit 61, a Fourier transforming unit 62, a comparing unit 63, a compensating unit 64, and an angle acquiring unit 65 as functional units.

[0044] The radar control method in which the control unit 6 controls the radar device 1 using the functions of the processor 6b is executed according to the control flow shown in Fig. 7. This control flow is executed repeatedly while the vehicle is running. Note that each "S" in this control flow represents a plurality of steps executed by a plurality of commands included in the control program.

[0045] First, in S10, the signal generating unit 60 causes the oscillator 2 to output a transmission signal. In the following S20, the AD converting unit 61 acquires, from the receiving circuit 4, a beat signal corresponding to a received signal that is the result of the transmission signal transmitted from the transmitting antenna TX to the outside world being reflected by a target and received by the receiving antenna RX. In S30, the AD converting unit 61 converts the beat signal into a digital signal through A / D conversion processing, which samples the beat signal at predetermined time intervals. In the following S40, the Fourier transforming unit 62 performs FFT (Fast Fourier Transform) processing for each chirp of the A / D converted beat signal. As a result, the Fourier transforming unit 62 acquires, for each chirp, a frequency spectrum (distance spectrum) that exhibits a peak at a frequency position corresponding to the distance to the target. The distance spectrum is data indicating the signal strength for each distance bin according to the distance resolution.

[0046] The Fourier transform unit 62 then performs FFT processing on the distance spectrum. That is, the Fourier transform unit 62 performs a second FFT processing on a waveform in which the phases at the distance bins obtained in the first FFT processing for the multiple chirps are arranged in time series. As a result, a frequency spectrum (velocity spectrum) showing a peak at a position corresponding to the relative velocity from the target is obtained for each velocity bin. By performing the above two-dimensional FFT, the Fourier transform unit 62 obtains two-dimensional information (RV map) showing peaks at positions corresponding to the distance to the target and the relative velocity of the target.

[0047] Next, in S50, the comparison unit 63 extracts a peak from the RV map. Subsequently, in S60, the comparison unit 63 acquires the intensity of the extracted peak. Then, in S70, the comparison unit 63 determines whether the extracted peak is valid. For example, the comparison unit 63 determines that the peak is valid if the intensity of the peak is within an allowable intensity range. Here, the allowable intensity range is a range in which the intensity is equal to or greater than a predetermined threshold. If it is determined that a valid peak exists, the flow proceeds to S80.

[0048] In S80, the compensation unit 64 obtains the phase error between the transmitting circuit 3 and the receiving circuit 4 based on the phase of the effective peak in each virtual channel.

[0049] In the phase compensation process, the compensation unit 64 defines a linear equation based on the phase difference of the peaks in the beat signal for each of Ns+Nr-2 or more pairs of virtual antennas V, each pair of which does not overlap with other pairs of pairs of transmitting circuits 3 and receiving circuits 4. This linear equation is defined with the relative phase error between the transmitting circuits 3 and the receiving circuits 4 as the unknown. The compensation unit 64 obtains the solution of this linear equation as the relative phase error. Because the beat signal is a signal related to the received signal, the phase difference of the peaks in the beat signal is an example of the result of comparing the received signals between virtual antennas V.

[0050] The acquisition of the relative phase error will be described in detail below. In the following description, the phase at the peak of the beat signal corresponding to the virtual antenna Vn is defined as θ Vn (n is a natural number). In the following explanation, for simplicity, only two pairs of (V11, V13) and (V12, V14) are used as pairs of the transmitting circuit 3 and the receiving circuit 4 that do not overlap with other pairs, as shown in FIG.

[0051] In this case, the phase difference θ of the peak relative to (V11, V13) V11 -θ V13 is the phase difference θ of the peaks related to equation (1), (V12, V14) V12 -θ V14 can be defined by the relationship shown in equation (2).

number

number

[0052] In the above formula, Θ a ,Θ b are the target-induced phase errors, and e tx1is the phase error of the signal generated in the first transmission circuit 3_1, e tx2 is the phase error of the signal generated in the second transmission 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.

[0053] Here, in the 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, when 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 taken into consideration, e tx1 ,e rx1 = 0. Therefore, the formulas (1) and (2) can be transformed into the following formulas (3) and (4).

number

number

[0054] Here, when Equations (3) and (4) are converted into a matrix format, the phase difference and relative phase error of each pair satisfy the relationship expressed by the following Equation (5).

number

[0055] Here, the term on the left side of equation (5) is a phase difference vector Y1 between the overlapping virtual antennas V. The first term on the right side of equation (5) is a coefficient matrix A1, and the second term is a phase error vector X1. In equation (5), the phase difference vector Y1 can be calculated from the phase of the peak in each beat signal. The coefficient matrix A1 is a constant matrix defined by the combination of the transmitting circuit 3 and the receiving circuit 4 of each pair of virtual antennas V. Therefore, equation (5) can be expressed as e tx2 ,e rx2 It is possible to solve the simultaneous equations with unknowns. That is, the compensation part istx2 ,e rx2 are obtained as the relative phase error of the second transmitting circuit 3_2 with respect to the first transmitting circuit 3_1 and the relative phase error of the second receiving circuit 4_2 with respect to the first receiving circuit 4_1.

[0056] In the following S90, the compensator 64 obtains the amplitude error between the transmitting circuits 3 and the receiving circuits 4 based on the amplitude of the effective peak in each virtual antenna V.

[0057] In amplitude compensation processing, similar to phase compensation processing, the compensator 64 defines a linear equation for each unique pair based on the amplitude difference of the peaks of the beat signal, with the amplitude error between the transmitting circuits 3 and the receiving circuits 4 as unknowns. The compensator 64 obtains the solution of this linear equation as the relative amplitude error. The amplitude difference of the peaks in the beat signal is an example of a comparison result of the received signals between the virtual antennas V.

[0058] In the following description, it is assumed that the same set of virtual antennas V as in the phase compensation process described above 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 denoted as A Vn (n is a natural number). In this case, the peak amplitude difference A V11 -A V13 is the amplitude difference A of the peaks related to equation (6), (V12, V14) V12 -A V14 can be defined by the relationship shown in equation (7).

number

number

[0059] In the above formula, G a ,G b are the amplitude errors due to the target, and G tx1 is the amplitude error of the signal generated in the first transmission circuit 3_1, G tx2is the amplitude error of the signal generated in 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.

[0060] Here, similarly to the phase compensation, when the relative amplitude error of the second transmitting circuit 3_2 with respect to the first transmitting circuit 3_1 and the relative amplitude error of the second receiving circuit 4_2 with respect to the first receiving circuit 4_1 are taken into consideration, G tx1 ,G rx1 = 0. Therefore, the formulas (6) and (7) can be transformed into the following formulas (8) and (9).

number

number

[0061] Here, when Equations (8) and (9) are converted into a matrix format, the amplitude difference and relative amplitude error of each pair satisfy the relationship expressed by Equation (10) below.

number

[0062] Here, the term on the left side of Equation (10) is the amplitude difference vector Y2 between the overlapping virtual antennas V. The first term on the right side of Equation (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 of each beat signal. The coefficient matrix A1 is a constant matrix defined by the combination of the transmitting circuit 3 and the receiving circuit 4 of each pair of virtual antennas V. That is, the compensating unit 64 calculates G as a solution of Equation (10). tx2 ,G rx2 are obtained as the relative amplitude error of the second transmitting circuit 3_2 with respect to the first transmitting circuit 3_1 and the relative amplitude error of the second receiving circuit 4_2 with respect to the first receiving circuit 4_1.

[0063] Then, in S100, the compensation unit 64 compensates for the phase error between the transmitting circuits 3 and between the receiving circuits 4. For example, the compensation unit 64 stores the acquired relative phase error in the memory 6a as compensation data to be used when acquiring a relative angle, which will be described later. Furthermore, in S110, the compensation unit 64 compensates for the relative amplitude error between the transmitting circuits 3 and between the receiving circuits 4 by storing it in the memory 6a as compensation data.

[0064] On the other hand, if it is determined in S70 that no valid peak exists, the flow proceeds to S120. In S120, the compensation unit 64 acquires the temperatures of each transmitting circuit 3 and each receiving circuit 4 from the temperature sensor 5. Then, in S130, the compensation unit 64 reads from the memory 6a a correction table for the phase error and amplitude error between the transmitting circuits 3 according to the temperature.

[0065] Next, in S140, the compensation unit 64 compares the acquired temperature with a correction table to obtain the relative phase error between the transmission circuits 3 and between the reception circuits 4. Then, in S150, the compensation unit 64 compares the acquired temperature with a correction table to obtain the relative amplitude error between the transmission circuits 3 and between the reception circuits 4. Then, in S160, the compensation unit 64 compensates for the relative phase error between the transmission circuits 3 and between the reception circuits 4. Furthermore, in S170, the compensation unit 64 compensates for the relative amplitude error between the transmission circuits 3 and between the reception circuits 4.

[0066] In S180 after S110 or S170, the angle acquisition unit 65 acquires the relative angle of the target. Specifically, the angle acquisition unit 65 acquires the phase difference between the virtual antennas V by performing FFT processing on multiple peaks extracted from the beat signal based on the received signal of each virtual antenna V after compensation. Since the phase difference between the virtual antennas V is related to the relative angle of the target, the angle acquisition unit 65 acquires the relative angle by converting the acquired phase difference into a relative angle.

[0067] According to this first embodiment, at least one of phase differences and amplitude differences between different transmitter circuits 3 and at least one of phase differences and amplitude differences between different receiver circuits 4 can be compensated for based on the comparison results of the received signals between the virtual antennas V in at least Ns+Nr-2 unique pairs. Therefore, it may be possible to compensate for errors not only between different receiver circuits 4 but also between different transmitter circuits 3. Furthermore, by arranging at least one of the transmitting antennas TX and the receiving antennas RX at uneven intervals, the aperture length of the virtual antenna may be larger than when the transmitting antennas TX are arranged at equal intervals. Specifically, in this embodiment, the transmitting antennas TX are arranged at uneven intervals of 4d and 6d, which results in a larger aperture length than when the transmitting antennas TX are arranged at equal intervals with the smaller interval of 4d. The aperture length here is the distance from one end to the other end of the virtual antenna V, i.e., the distance from virtual antenna V1 to virtual antenna V24 shown in FIG. 4 . The aperture length in this embodiment is 21d. Therefore, it may be possible to achieve both compensation accuracy and spatial resolution.

[0068] Second Embodiment The second embodiment is a modified example of the first embodiment, as shown in Figures 8 to 11. In the second embodiment, the transmitting antenna TX and the receiving antenna RX are arranged two-dimensionally.

[0069] As an example, assume that the radar device 1 is equipped with 12 transmitting antennas TX and 16 receiving antennas RX. Furthermore, 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, as shown in FIG. 8 , 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. In the following, the four transmitting circuits 3 may be distinguished 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 distinguished 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.

[0070] In this embodiment, each circuit is mounted on a plurality of 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. The second transmitting circuit 3_2 and the second receiving circuit 4_2 are mounted on the same second circuit chip C2. In addition, the third transmitting circuit 3_3 and the third receiving circuit 4_3 are mounted on the same third circuit chip C3. The fourth transmitting circuit 3_4 and the fourth receiving circuit 4_4 are mounted on the same fourth circuit chip C4. The wiring lengths of the wirings Wt between the transmitting antennas TX and the corresponding transmitting circuits 3 are all substantially the same. The wiring lengths of the wirings Wr between the receiving antennas RX and the corresponding receiving circuits 4 are all substantially the same.

[0071] Furthermore, in the following description, the 12 transmitting antennas TX and the 16 receiving antennas RX may be distinguished by assigning different reference symbols to them. Specifically, the three transmitting antennas TX connected to the first transmitting circuit 3_1 are referred to as transmitting antennas TX4, TX5, and TX6, the three transmitting antennas TX connected to the second transmitting circuit 3_2 are referred to as transmitting antennas TX1, TX2, and TX3, the three transmitting antennas TX connected to the third transmitting circuit 3_3 are referred to as transmitting antennas TX7, TX8, and TX9, and the three transmitting antennas TX connected to the fourth transmitting circuit 3_4 are referred to as transmitting antennas TX10, TX11, and TX12.

[0072] The four receiving antennas RX connected to the first receiving circuit 4_1 are referred to as receiving antennas RX5, RX6, RX7, and RX8, the four receiving antennas RX connected to the second receiving circuit 4_2 are referred to as receiving antennas RX1, RX2, RX3, and RX4, the four receiving antennas RX connected to the third receiving circuit 4_3 are referred to as receiving antennas RX9, RX10, RX11, and RX12, and the four receiving antennas RX connected to the fourth receiving circuit 4_4 are referred to as receiving antennas RX13, RX14, RX15, and RX16.

[0073] The above-described transmitting antennas TX and receiving antennas RX are arranged two-dimensionally. As shown in FIG. 9, four rows of multiple transmitting antennas TX arranged in the X direction are spaced apart in the Y direction. Of these four rows arranged in the X direction, the first, second, and fourth rows from the origin side each have two transmitting antennas TX. Furthermore, of the four rows arranged in the X direction, the third row from the origin side has six transmitting antennas TX. Here, the interval between one scale division in the X direction is defined as d, and the interval between one scale division in the Y direction is defined as s. The transmitting antennas TX12, TX10, and TX9 are arranged at equal intervals of d. The transmitting antennas TX5, TX4, and TX3 are also arranged at equal intervals of d. Meanwhile, the transmitting antenna TX9 and the transmitting antenna TX5 are spaced apart by an interval of 20d. That is, in this third row, the transmitting antennas TX are arranged at unequally spaced intervals in the X direction.

[0074] Furthermore, two rows of multiple receiving antennas RX aligned in the X direction are arranged spaced apart in the Y direction. Eight receiving antennas TX are arranged in each of these two rows aligned in the X direction. In each row, these receiving antennas RX are arranged at equal intervals in the X direction. Furthermore, of the two rows aligned in the X direction, the first row from the origin side is aligned so as to align with the first row of transmitting antennas TX from the origin side in the Y direction. Furthermore, of the two rows aligned in the X direction, the second row from the origin side is aligned so as to align with the fourth row of transmitting antennas TX from the origin side in the Y direction.

[0075] The number of virtual antennas V is assumed to be the same as the number of receiving antennas RX for each of the 12 transmitting antennas TX, that is, 16. Therefore, a total of 192 virtual antennas V are assumed. Specifically, the 192 virtual antennas V are assumed to be arranged as shown in FIGS. 10 and 11.

[0076] In the following, 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 and b are natural numbers) is expressed as Vc (c=(a-1)×16+b). Note that in Fig. 10, "V" is omitted to avoid complication.

[0077] As shown in Figures 10 and 11, there are 24 pairs of virtual antennas V whose virtual positions overlap. Among these, there are 13 unique pairs whose combinations of transmitter circuits 3 and receiver circuits 4 do not overlap with other pairs. For example, the following pairs can be considered as unique pairs: (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). The compensation unit 64, described below, performs compensation processing based on received signals acquired by at least six pairs of virtual antennas V from these pairs.

[0078] Note that the set of virtual antennas V assumed for compensation processing may be other than the above-mentioned sets, as long as the combination of the transmitter circuit 3 and the receiver circuit 4 does not overlap with other sets. For example, (VV3, V86) and (V4, V87) overlap with (V2, V85) in terms of the combination of the transmitter circuit 3 and the receiver circuit 4, but do not overlap with other sets. Therefore, assuming (V3, V86) or (V4, V87) as one of the 13 sets is equivalent to assuming (V2, V85).

[0079] In addition, when the number of antennas TX and RX is relatively large as described above, the arrangement of the antennas TX and RX can be determined using a genetic algorithm. For example, characteristics for evaluating the current generation generated by the genetic algorithm include overlap efficiency, rank, wiring efficiency, FOV, and separation angle. Overlap efficiency is a parameter obtained by dividing the full rank number by the number of channels reduced due to overlap of virtual positions, and a large value is desirable. Rank is a predetermined parameter. Wiring efficiency is a parameter corresponding to the dispersion of antenna coordinates input to the same circuit, and a small value is desirable. FOV is a parameter corresponding to the distance between antennas, and a small value is desirable. Separation angle is a parameter corresponding to the aperture length, and a large value is desirable.

[0080] (Third embodiment) As shown in FIGS. 12 to 16, the third embodiment is a modification of the first embodiment.

[0081] 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 individual circuits 3 and antennas TX, RX may be distinguished by being assigned the same reference numerals as those in the first embodiment.

[0082] In the radar device 1 of the third embodiment, at least one transmitting antenna TX has a wiring length different from that of the other transmitting antennas TX. In the example shown in Fig. 11, 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. Also, the wiring lengths of the respective wirings Wr of the receiving antennas RX are all substantially the same.

[0083] When antennas with different wiring lengths exist, the transmitting antenna TX and receiving antenna RX are arranged so that the number of unique pairs of virtual antennas V, which are pairs of virtual antennas V whose combinations of transmitting circuits 3 and receiving circuits 4 do not overlap with other pairs, among the set of pairs of virtual antennas whose virtual positions overlap among the group of virtual antennas V assumed for each transmitting antenna TX and whose combinations of transmitting circuits 3 and receiving circuits 4 do not match, is at least Ns+Nr-2 pairs.

[0084] The transmitting antennas TX and receiving antennas RX are arranged so as to include at least one different wiring length set, which is a set of virtual antennas whose virtual positions overlap and whose wiring lengths do not match. Furthermore, the transmitting antennas TX and receiving antennas RX are arranged so that the total number of belonging sets, which are sets of virtual antennas V belonging to at least one of the above-mentioned unique set and different wiring length sets, is at least Ns+Nr-1 sets.

[0085] As shown in Fig. 13, transmitting antennas TX1_1, TX1_2, TX2_1, and TX2_2 are arranged in this order from one side to the other in the X direction. The transmitting antennas TX1_1 and TX1_2 are arranged with an interval of 6d between them. The transmitting antennas TX1_2 and TX2_1 are arranged with an interval of 3d between them. And the transmitting antennas TX2_1 and TX2_2 are arranged with an interval of 6d between them.

[0086] 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.

[0087] The number of virtual antennas V is assumed to be the same as the number of receiving antennas RX, that is, six, for each of the transmitting antennas TX1_1, TX1_2, TX2_1, and TX2_2. Therefore, a total of 24 virtual antennas V are assumed.

[0088] Here, the multiple virtual antennas V assumed for the transmitting antenna TX1_1 are, from one side to the other, virtual antennas V1, V2, V3, V4, V5, and V6. The multiple virtual antennas V assumed for the transmitting antenna TX1_2 are, from one side to the other, virtual antennas V7, V8, V9, V10, V11, and V12. The group of virtual antennas V assumed for the transmitting antenna TX2_1 are, from one side to the other, virtual antennas V13, V14, V15, V16, V17, and V18. The group of virtual antennas V assumed for the transmitting antenna TX2_2 are, from one side to the other, virtual antennas V19, V20, V21, V22, V23, and V24.

[0089] Because the transmitting antennas TX1_1 and TX1_2 are arranged at an interval of 6d, the virtual antenna group V assumed for the transmitting antenna TX1_1 is at a virtual position relatively shifted by 6d from the virtual antenna group V assumed for the transmitting antenna TX1_2. Furthermore, because the transmitting antennas TX1_2 and TX2_1 are arranged at an interval of 3d, the virtual antenna group V assumed for the transmitting antenna TX1_2 is at a virtual position relatively shifted by 3d from the virtual antenna group V assumed for the transmitting antenna TX2_1. Furthermore, because the transmitting antennas TX2_1 and TX2_2 are arranged at an interval of 6d, the virtual antenna group V assumed for the transmitting antenna TX2_1 is at a virtual position relatively shifted by 6d from the virtual antenna group V assumed for the transmitting antenna TX2_2.

[0090] Therefore, in such an arrangement of antennas TX and RX, there are three pairs of virtual antennas V whose virtual positions overlap, as shown in Fig. 14. Specifically, (V10, V13), (V11, V14), and (V12, V15) are the pairs of virtual antennas V whose virtual positions overlap, respectively.

[0091] The above three sets are a set of sets in which the combinations of the transmitting circuits 3 and the receiving circuits 4 do not match among the virtual antennas V. Furthermore, these three sets are sets in which the combinations of the transmitting circuits 3 and the receiving circuits 4 do not overlap with each other. Therefore, the number of unique sets in this antenna arrangement is three, which satisfies the condition of at least Ns+Nr-2 sets.

[0092] Furthermore, these three sets are different wiring length sets. That is, the wiring lengths of virtual antennas V10, V11, and V12 are longer than the wiring lengths of virtual antennas V13, V14, and V15. Therefore, the number of different wiring length sets in this antenna arrangement is one set, which satisfies the condition of at least one set. Furthermore, as a result of the above, the number of belonging sets in this antenna arrangement is three sets, which satisfies the condition of at least Ns+Nr-1 sets.

[0093] In this case, in the processes of S80 and S90, the control unit 6 further calculates a phase error and an amplitude error according to the wiring length difference of the virtual antenna V. Here, the wiring length of the virtual antenna V means the sum of the 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, only the wiring Wt2 is longer than the wiring Wt1, and all the wirings Wr of the receiving antenna RX are substantially the same length, so the wiring length of the virtual antenna V assumed for the transmitting antenna TX1_2 is longer than the wiring lengths of the virtual antennas V assumed for the transmitting antennas TX other than the transmitting antenna TX1_2.

[0094] Generally, as shown in FIG. 15, the phase error due to the wiring length difference for each virtual antenna V increases linearly according to the wiring length difference from the reference wiring length Lo (e.g., the shortest wiring length). That is, the phase error for the wiring length difference is a value obtained by multiplying the wiring length difference by K. Here, the slope K related to the magnitude of the phase error for the wiring length difference is a temperature parameter that changes with temperature. That is, when 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 antennas TX other than the transmitting antenna TX1_2.

[0095] Here, the difference in wiring length in the virtual antenna V assumed for the pair of the transmitting antenna TXa_b and the receiving antenna RXc_d is expressed as L abcd (a, b, c, d are natural numbers). The compensation unit 64 uses the three groups (V10, V13), (V11, V14), and (V12, V15) as the groups, as described above. The wiring length difference L abcd The phase error caused by e abcd In the example shown in FIG. 16, the phase difference θ of the peaks related to (V10, V13) is V10 -θ V13 is the phase difference θ of the peaks related to equation (11), (V11, V14) V11 -θ V14 is the phase difference θ of the peaks related to equation (12), (V12, V15) V12 -θ V15 can be defined by the relationship shown in Equation (13).

number

number

number

[0096] Here, the phase error e abcd , L abcdWhen substituted with K, the above formulas (11) to (12) can be transformed into the following formulas (14) to (16).

number

number

number

[0097] When this is converted into a matrix format, the phase difference and relative phase error of each pair are expressed by the following formula ( 17) satisfies the relationship shown in

number

[0098] Here, the term on the left side of Equation (17) is a phase difference vector Y3 between the overlapping virtual antennas V. The first term on the right side of Equation (17) is a coefficient matrix A3, and the second term is a phase error vector X3. The phase difference vector Y3 in Equation (17) can be calculated from the phase of the peak in each beat signal. The coefficient matrix A3 is a constant matrix defined by the combination of the transmitting circuit 3, receiving circuit 4, and wiring length difference of each pair of virtual antennas V. Therefore, Equation (17) can be expressed as e tx2 ,e rx2 , K as unknowns. That is, the compensation unit 64 calculates e as a solution of the equation (17). tx2 ,e rx2 , K are acquired 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 according to the wiring length difference.

[0099] In amplitude compensation processing, similar to phase compensation processing, the compensating unit 64 defines a linear equation based on the amplitude difference of the peaks of the beat signals for each of Ns+Nr-1 or more pairs of virtual antennas V, each pair of which does not overlap with other pairs of combinations of transmitting circuits 3 and receiving circuits 4, with the amplitude error between the transmitting circuits 3 and receiving circuits 4 being the unknown. The compensating unit 64 obtains the solution of this linear equation as the amplitude error.

[0100] The amplitude error due to the difference in wiring length from the reference wiring length Lo increases linearly with the difference in wiring length from the reference wiring length, similar to the phase error. The increase in amplitude error due to the difference in wiring length changes with temperature. In other words, the amplitude error due to the difference in wiring length is the value obtained by multiplying the difference in wiring length by the temperature parameter α.

[0101] Wiring length difference L abcd The amplitude error caused by G abcd Then, the amplitude difference A of the peak for (V10, V13) V10 -A V13 is the amplitude difference A of the peaks related to equation (18), (V11, V14) V11 -A V14 is the amplitude difference A of the peaks related to equation (19), (V12, V15) V12 -A V15 can be defined by the relationship shown in equation (20).

number

number

number

[0102] Here, the amplitude error G abcd , L abcd When substituted with α, the above formulas (18) to (20) can be transformed into the following formulas (21) to (23).

number

number

number

[0103] When Equations (21) to (23) are converted into a matrix format, the amplitude difference and relative amplitude error of each pair satisfy the relationship expressed by Equation (24) below.

number

[0104] Here, the term on the left side of Equation (24) is the amplitude difference vector Y4 between the overlapping virtual antennas V. The first term on the right side of Equation (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 of 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 pair of virtual antennas V. That is, the compensating unit 64 calculates G as a solution of Equation (28). tx2 ,G rx2 , α are acquired 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 due to the wiring length.

[0105] According to this third embodiment, at least one of a phase difference and an amplitude difference between different transmitter circuits, a phase difference and an amplitude difference between different receiver circuits, and a phase difference and an amplitude difference corresponding to a difference in wiring length between virtual antennas can be compensated for based on a comparison result between the received signals of at least Ns+Nr-1 groups. Therefore, it is possible to compensate for errors between different transmitter circuits and errors due to differences in wiring length, in addition to errors between different receiver circuits. Furthermore, by arranging at least one of the transmitter antennas and the receiver antennas at uneven intervals, the aperture length of the virtual antenna can be larger than when the antennas are arranged at equal intervals. Therefore, it is possible to achieve both compensation accuracy and spatial resolution.

[0106] (Fourth embodiment) As shown in FIG. 17, the fourth embodiment is a modification of the second embodiment.

[0107] 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 shown in Fig. 9. On the other hand, the assumed wiring lengths of each virtual antenna V have the relative relationship shown in the graph of Fig. 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 specified so that the wiring lengths of the corresponding virtual antennas V have the relative relationship shown in Fig. 17.

[0108] Here, since Ns=4 and Nr=4, in the processes of S80 and S90, 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, from the beat signals of at least seven of the belonging pairs.

[0109] (Other embodiments) Although multiple embodiments have been described above, the present disclosure should not be construed as being limited to those embodiments, and can be applied to various embodiments and combinations within the scope that does not deviate from the gist of the present disclosure.

[0110] In a modification of the second embodiment, both the transmitting antennas TX and the receiving antennas RX may be arranged at unequal intervals. Specifically, as shown in Fig. 18, the transmitting antennas TX and the receiving antennas RX may be arranged two-dimensionally at unequal intervals. In the arrangement shown in Fig. 18, the virtual antenna V is arranged at a virtual position shown in Fig. 19.

[0111] In a modified example, the dedicated computer constituting the control unit 6 may be a sensor management ECU that comprehensively controls multiple types of sensors mounted on the vehicle. The dedicated computer constituting the control unit 6 may be an integration ECU that integrates vehicle driving control. The dedicated computer constituting the control unit 6 may be a determination ECU that determines a driving task in vehicle driving control. The dedicated computer constituting the control unit 6 may be a monitoring ECU that monitors vehicle driving control. The dedicated computer constituting the control unit 6 may be an evaluation ECU that evaluates vehicle driving control. The dedicated computer constituting the control unit 6 may be a navigation ECU that navigates the vehicle's driving route. The dedicated computer constituting the control unit 6 may be a locator ECU that estimates the vehicle's own state quantity. The dedicated computer constituting the control unit 6 may be an actuator ECU that controls the vehicle's driving actuators. The dedicated computer constituting the control unit may be an HCU (Human Machine Interface (HMI) Control Unit) that controls information presentation in the vehicle. The dedicated computer constituting the control unit 6 may be a computer outside the vehicle, for example, an external center or mobile terminal that can communicate with the vehicle.

[0112] In a modified example, the mobile body to which the radar device 1 is applied may be, for example, an autonomous robot capable of transporting luggage or collecting information by autonomous or remote traveling. Examples of the autonomous robot include an autonomous vehicle. In addition to the forms described so far, the above-mentioned embodiment and modified example may be implemented in the form of a processing circuit (e.g., a processing ECU, etc.) or a semiconductor device (e.g., a semiconductor chip, etc.) as a control device that is configured to be mountable on a mobile body and has at least one processor 6b and one memory 6a.

[0113] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with the subsequent clause referring to the preceding clause as an alternative. Furthermore, some clauses may be written in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0114] (Technical thought 1) a plurality of transmit antennas (TX) and a plurality of receive antennas (RX); Ns transmitting circuits (3) connected to the transmitting antennas and outputting transmission signals; Nr receiving circuits (4) connected to the receiving antennas and configured to acquire received signals; a control unit (6) that processes the received signal, The Ns and the Nr are each an integer of 2 or more, The plurality of transmitting antennas and the plurality of receiving antennas are at least one of the virtual antennas is arranged at unequal intervals, and among a set of virtual antenna pairs in which virtual positions overlap among groups of virtual antennas (V) assumed for each of the transmitting antennas for the plurality of receiving antennas in accordance with a phase difference of the received signals between the receiving antennas and in which combinations of the transmitting circuit and the receiving circuit do not match, at least Ns+Nr-2 unique sets of virtual antenna pairs in which combinations of the transmitting circuit and the receiving circuit do not overlap with other sets are included; The control unit a radar device that performs compensation processing to compensate 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, based on a comparison result of the reception signals between the virtual antennas in at least Ns+Nr-2 unique sets.

[0115] (Technical thought 2) a plurality of transmit antennas (TX) and a plurality of receive antennas (RX); Ns transmitting circuits (3) connected to the transmitting antennas and outputting transmission signals; Nr receiving circuits (4) connected to the receiving antennas and configured to acquire received signals; a control unit (6) that processes the received signal, The Ns and the Nr are each an integer of 2 or more, The plurality of transmitting antennas and the plurality of receiving antennas are At least one of them is arranged at uneven intervals, Among a set of virtual antenna pairs in which virtual positions overlap among groups of virtual antennas (V) assumed for each of the transmitting antennas for the plurality of receiving antennas in accordance with the phase difference of the received signals between the receiving antennas and in which combinations of the transmitting circuit and the receiving circuit do not match, at least Ns+Nr-2 unique pairs are included, which are sets of virtual antennas in which combinations of the transmitting circuit and the receiving circuit do not overlap with other pairs; At least one different wiring length pair is included, which is a pair of the virtual antennas whose virtual positions overlap and whose wiring lengths do not match, and the total number of belonging sets, which are sets of the virtual antennas belonging to at least one of the specific set and the different wiring length set, is at least Ns+Nr-1 sets; The control unit a radar device that executes a compensation process to compensate for at least one of a phase difference and an amplitude difference corresponding to a difference in wiring length between the virtual antennas, at least one of a phase difference and an amplitude difference between the different transmission circuits, and at least one of a phase difference and an amplitude difference between the different reception circuits, based on a comparison result of the reception signals between the virtual antennas in at least Ns+Nr-1 belonging groups.

[0116] (Technical Thought 3) The radar device according to Technical Idea 1 or Technical Idea 2, wherein the control unit performs the compensation process by further utilizing the comparison result of the received signals between the virtual antennas in the set of virtual antennas where the combination of the transmission circuit and the reception circuit overlaps with another set.

[0117] (Technical Thought 4) Further, a temperature sensor (5) is provided to detect the temperatures of the transmitting circuit and the receiving circuit, The control unit determining whether the received signal is valid for the compensation process; A radar device according to any one of technical ideas 1 to 3, which executes the compensation process based on the temperatures of the transmitting circuit and the receiving circuit when it is determined that the received signal is not valid for the compensation process.

[0118] (Technical Thought 5) The radar device according to any one of Technical Ideas 1 to 4, wherein the transmitting antenna and the receiving antenna are arranged one-dimensionally.

[0119] (Technical Thought 6) The radar device according to any one of Technical Ideas 1 to 4, wherein at least one of the transmitting antenna and the receiving antenna is arranged two-dimensionally. [Explanation of symbols]

[0120] 1: radar device, 3: transmitting circuit, 4: receiving circuit, 5: temperature sensor, 6: control unit (control section), 6a: memory, 6b: processor, TX: transmitting antenna, RX: receiving antenna, V: virtual antenna

Claims

1. a plurality of transmit antennas (TX) and a plurality of receive antennas (RX); Ns transmitting circuits (3) connected to the transmitting antennas and outputting transmission signals; Nr receiving circuits (4) connected to the receiving antennas and configured to acquire received signals; a control unit (6) that processes the received signal, The Ns and the Nr are each an integer of 2 or more, The plurality of transmitting antennas and the plurality of receiving antennas are at least one of the virtual antennas is arranged at unequal intervals, and among a set of virtual antenna pairs in which virtual positions overlap among groups of virtual antennas (V) assumed for each of the transmitting antennas for the plurality of receiving antennas in accordance with the phase difference of the received signal between the receiving antennas and the combinations of the transmitting circuit and the receiving circuit do not match, at least Ns+Nr-2 unique sets of virtual antenna pairs in which the combinations of the transmitting circuit and the receiving circuit do not overlap with other sets are included; The control unit a compensation process for compensating for a phase difference between the different transmission circuits and a phase difference between the different reception circuits based on a phase difference of a peak in a beat signal, which is a comparison result of the reception signals of the virtual antennas in at least Ns+Nr-2 unique sets; and a compensation process for compensating for an amplitude difference between the different transmission circuits and an amplitude difference between the different reception circuits based on an amplitude difference of a peak in a beat signal, which is the comparison result.

2. a plurality of transmit antennas (TX) and a plurality of receive antennas (RX); Ns transmitting circuits (3) connected to the transmitting antennas and outputting transmission signals; Nr receiving circuits (4) connected to the receiving antennas and configured to acquire received signals; a control unit (6) that processes the received signal, The Ns and the Nr are each an integer of 2 or more, The plurality of transmitting antennas and the plurality of receiving antennas are At least one of them is arranged at uneven intervals, Among a set of pairs of virtual antennas in which virtual positions overlap among groups of virtual antennas (V) assumed for each of the transmitting antennas for the plurality of receiving antennas in accordance with a phase difference of the received signals between the receiving antennas and in which combinations of the transmitting circuit and the receiving circuit do not match, at least Ns+Nr-2 pairs of unique pairs are included, which are sets of virtual antennas in which combinations of the transmitting circuit and the receiving circuit do not overlap with other pairs; at least one different wiring length pair is included, which is a pair of the virtual antennas whose virtual positions overlap and whose wiring lengths do not match, and the total number of belonging sets, which are sets of the virtual antennas belonging to at least one of the specific set and the different wiring length set, is at least Ns+Nr-1 sets; The control unit a compensation process for compensating for a phase difference corresponding to a difference in wiring length between the virtual antennas, a phase difference between the different transmission circuits, and a phase difference between the different reception circuits, based on a phase difference of peaks in a beat signal, which is a comparison result of the reception signals between the virtual antennas in at least Ns+Nr-1 belonging groups; and a compensation process for compensating for an amplitude difference corresponding to a difference in wiring length between the virtual antennas, an amplitude difference between the different transmission circuits, and an amplitude difference between the different reception circuits, based on an amplitude difference of peaks in a beat signal, which is the comparison result.

3. 3. The radar device according to claim 1, wherein the control unit performs the compensation process by further utilizing a result of the comparison of the received signals between the virtual antennas in a set of virtual antennas in which a combination of the transmission circuit and the reception circuit overlaps with another set.

4. Further provided is a temperature sensor (5) for detecting the temperatures of the transmitting circuit and the receiving circuit, The control unit determining whether the received signal is valid for the compensation process; 3. The radar device according to claim 1, wherein, when it is determined that the received signal is not valid for the compensation process, the compensation process is performed based on temperatures of the transmission circuit and the reception circuit.

5. 3. The radar device according to claim 1, wherein the transmitting antenna and the receiving antenna are arranged one-dimensionally.

6. 3. The radar device according to claim 1, wherein at least one of the transmitting antenna and the receiving antenna is arranged two-dimensionally.

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