Radar signal processing device, radar signal processing method, and radar device

Abstract

A radar signal processing device (5) is configured to comprise: a reception signal acquisition unit (11) for acquiring respective reception signals in a plurality of reception antennas (3-1) to (3-NRx); a spectrum calculation unit (12) for calculating an initial value of a two-dimensional spectrum indicating the direction in which a target is present and the speed of the target on the basis of the reception signals acquired by the reception signal acquisition unit (11); and a spectrum update unit (13) for updating the two-dimensional spectrum on the basis of a nonlinear component included in the spectrum of the speed in the two-dimensional spectrum and the position error of the reception antenna included in the spectrum of an angle in the two-dimensional spectrum.

Description

Radar signal processing device, radar signal processing method, and radar device

[0001] The present disclosure relates to a radar signal processing device, a radar signal processing method, and a radar device.

[0002] There is a radar signal processing device that calculates the direction of a target based on signals received by multiple receiving antennas. For example, Non-Patent Document 1 discloses a radar signal processing device that can estimate the direction of a target with high accuracy even when there is an unknown position error in the installation position of the receiving antenna. This radar signal processing device uses a ReIterative Super Resolution (RISR) method as a method for estimating the direction of a target.

[0003] CC Jones et al., “Development & Experimental Assessment of Robust Direction Finding and Self-Calibration,” in Proc. IEEE Radar Conf., Mar. 2022.

[0004] The radar signal processing device disclosed in Non-Patent Document 1 has a technique for calculating the direction of a target when there is an unknown position error in the installation position of the receiving antenna, but has a problem in that it does not have a technique for calculating the speed of the target.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a radar signal processing device that can calculate not only the direction in which a target exists but also the speed of the target when there is an unknown position error in the installation position of the receiving antenna.

[0006] A radar signal processing device according to the present disclosure includes a received signal acquisition unit that acquires received signals from a plurality of receiving antennas, a spectrum calculation unit that calculates an initial value of a two-dimensional spectrum that indicates the direction in which a target exists and the speed of the target based on the received signals acquired by the received signal acquisition unit, and a spectrum update unit that updates the two-dimensional spectrum based on a nonlinear component included in the speed spectrum in the two-dimensional spectrum and a position error of the receiving antenna included in the angle spectrum in the two-dimensional spectrum.

[0007] According to the present disclosure, when there is an unknown position error in the installation position of the receiving antenna, it is possible to calculate not only the direction in which the target exists but also the velocity of the target.

[0008] 1 is a configuration diagram showing a radar device including a radar signal processing device 5 according to a first embodiment; FIG. 2 is a hardware configuration diagram showing hardware of the radar signal processing device 5 according to the first embodiment; FIG. 3 is a hardware configuration diagram of a computer when the radar signal processing device 5 is realized by software, firmware, or the like; and FIG. 4 is a diagram showing a relationship between a vehicle on which the radar device is installed and a target, and a receiving antenna 3-j (j=1, ..., N Ｒｘ ) position error Δd ｊ The position error Δd of the transmitting antenna 2-i (i=1, 2, 3) is ｉ 1 is an explanatory diagram showing the relationship between a vehicle on which the radar device is installed and a target, and the relationship between the vehicle on which the radar device is installed and the target, and the receiving antennas 3-j (j=1, ..., N Ｒｘ ) position error Δd ｊ 1 is an explanatory diagram showing the relationship between the vehicle on which the radar device is installed and the target, and the receiving antenna 3-j (j=1, . . . , N Ｒｘ ) position error Δd ｊ1 is an explanatory diagram showing the relationship between the vehicle on which the radar device is installed and the target, and the receiving antenna 3-j (j=1, . . . , N Ｒｘ ) position error Δd ｊ 2D spectrum x ｍ，ｎ FIG. 10 is an explanatory diagram showing an example of hat display.

[0009] In order to explain the present disclosure in more detail, embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0010] First Embodiment Fig. 1 is a configuration diagram showing a radar device including a radar signal processing device 5 according to a first embodiment. Fig. 2 is a hardware configuration diagram showing the hardware of the radar signal processing device 5 according to the first embodiment. The radar device shown in Fig. 1 includes a transmitter 1, transmitting antennas 2-1 to 2-N, Ｔｘ , receiving antennas 3-1 to 3-N Ｒｘ , a receiver 4, a radar signal processing device 5, and a display device 6. Ｔｘ is an integer equal to or greater than 1, and N Ｒｘ is an integer of 2 or greater.

[0011] The transmitter 1 transmits, as a transmission signal, for example, a pulse to the transmission antennas 2-1 to 2-N. Ｔｘ The transmitter 1 outputs to the transmitting antennas 2-1 to 2-N. Ｔｘ The timing at which the pulses are output to the transmitting antennas 2-i (i=1, . . . , N Ｔｘ ) emits a transmission signal, for example, a pulse, toward the target. Ｔｘ The transmission timings of the pulses at are different from each other.

[0012] Receiving antenna 3-j (j=1, . . . , N Ｒｘ ) receives a received signal, which is a transmitted signal after reflection by a target. The receiving antenna 3-j outputs the received signal to the receiver 4. The receiver 4 demodulates the received signal output from the receiving antenna 3-j and converts the demodulated received signal from an analog signal to a digital signal. The receiver 4 outputs a digital signal to the radar signal processing device 5 as the received signal of the receiving antenna 3-j.

[0013] The radar signal processing device 5 includes a received signal acquisition unit 11, a spectrum calculation unit 12, and a spectrum update unit 13. The display device 6 displays the two-dimensional spectrum calculated by the radar signal processing device 5. The two-dimensional spectrum indicates the direction in which a target exists and the speed of the target. In the radar device shown in FIG. 1 , the radar signal processing device 5 outputs the two-dimensional spectrum to the display device 6, which then displays the two-dimensional spectrum. However, this is merely an example, and the radar signal processing device 5 may output the two-dimensional spectrum to, for example, a tracking device (not shown), and the tracking device may track the target based on the two-dimensional spectrum.

[0014] The received signal acquisition unit 11 is realized by, for example, the received signal acquisition circuit 21 shown in Fig. 2. The received signal acquisition unit 11 receives the signal from the receiver 4 via the receiving antenna 3-j (j = 1, ..., N Ｒｘ The received signal acquisition unit 11 outputs the received signal to the spectrum calculation unit 12.

[0015] The spectrum calculation unit 12 is realized by, for example, the spectrum calculation circuit 22 shown in FIG. 2 . The spectrum calculation unit 12 acquires the received signal from the received signal acquisition unit 11. The spectrum calculation unit 12 calculates an initial value of a two-dimensional spectrum indicating the direction in which a target exists and the speed of the target based on the received signal. The target is a moving object such as a vehicle, an airplane, or an animal. If the radar device shown in FIG. 1 is installed on, for example, a vehicle, the speed of the target indicated by the two-dimensional spectrum is the relative speed of the target with respect to the vehicle on which the radar device is installed. If the radar device shown in FIG. 1 is installed on, for example, a road structure, the speed of the target indicated by the two-dimensional spectrum is the absolute speed of the target. The spectrum calculation unit 12 outputs the initial value of the two-dimensional spectrum to the spectrum update unit 13.

[0016] The spectrum updater 13 is realized by, for example, the spectrum update circuit 23 shown in Fig. 2. The spectrum updater 13 includes a first update processor 13a, a second update processor 13b, and a third update processor 13c. The spectrum updater 13 acquires the initial value of the two-dimensional spectrum from the spectrum calculator 12. The spectrum updater 13 calculates the nonlinear components contained in the velocity spectrum in the two-dimensional spectrum (hereinafter referred to as "velocity spectrum") and the nonlinear components contained in the angle spectrum in the two-dimensional spectrum (hereinafter referred to as "angle spectrum") for the receiving antennas 3-1 to 3-N. Ｒｘ The two-dimensional spectrum is updated based on the position error of the two-dimensional spectrum. When the updating process of the two-dimensional spectrum is completed, the spectrum updating unit 13 outputs the updated two-dimensional spectrum to the display device 6, for example.

[0017] The first update processing unit 13a acquires an initial value of the two-dimensional spectrum from the spectrum calculation unit 12. The first update processing unit 13a updates the two-dimensional spectrum based on the nonlinear components included in the velocity spectrum. Specifically, the first update processing unit 13a updates the two-dimensional spectrum based on the nonlinear components included in the velocity spectrum that are caused by the acceleration of the target. Furthermore, the first update processing unit 13a updates the two-dimensional spectrum based on the nonlinear components included in the velocity spectrum that are caused by the acceleration of the target. Ｔｘ The first updating unit 13a updates the two-dimensional spectrum based on a nonlinear component caused by variations in the transmission intervals of the pulses transmitted from the first updating unit 13a. The first updating unit 13a outputs the updated two-dimensional spectrum to the second updating unit 13b.

[0018] The second update processing unit 13b acquires the updated two-dimensional spectrum from the first update processing unit 13a. The second update processing unit 13b updates the two-dimensional spectrum of the receiving antennas 3-1 to 3-N included in the angular spectrum. Ｒｘ The second updating unit 13b updates the two-dimensional spectrum after updating by the first updating unit 13a based on the position error of the second updating unit 13a. The second updating unit 13b outputs the updated two-dimensional spectrum to the third updating unit 13c.

[0019] The third update processing unit 13c obtains the updated two-dimensional spectrum from the second update processing unit 13b. The third update processing unit 13c performs a process of determining the nonlinear components included in the velocity spectrum and the two-dimensional spectrum of the receiving antennas 3-1 to 3-N. Ｎｘ The second update processor 13b updates the two-dimensional spectrum after updating based on the coupling error with the position error of the second update processor 13b. The third update processor 13c outputs the updated two-dimensional spectrum to the display device 6, for example.

[0020] 1, it is assumed that each of the received signal acquisition unit 11, the spectrum calculation unit 12, and the spectrum update unit 13, which are components of the radar signal processing device 5, is realized by dedicated hardware as shown in Fig. 2. That is, it is assumed that the radar signal processing device 5 is realized by a received signal acquisition circuit 21, a spectrum calculation circuit 22, and a spectrum update circuit 23. Each of the received signal acquisition circuit 21, the spectrum calculation circuit 22, and the spectrum update circuit 23 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.

[0021] The components of the radar signal processing device 5 are not limited to those realized by dedicated hardware, and the radar signal processing device 5 may be realized by software, firmware, or a combination of software and firmware. The software or firmware is stored as a program in the memory of a computer. The computer refers to hardware that executes a program, and includes, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor).

[0022] 3 is a hardware configuration diagram of a computer when the radar signal processing device 5 is realized by software, firmware, etc. When the radar signal processing device 5 is realized by software, firmware, etc., a program for causing the computer to execute the respective processing procedures of the received signal acquisition unit 11, the spectrum calculation unit 12, and the spectrum update unit 13 is stored in a memory 31. Then, a processor 32 of the computer executes the program stored in the memory 31.

[0023] 2 shows an example in which each of the components of the radar signal processing device 5 is realized by dedicated hardware, while Fig. 3 shows an example in which the radar signal processing device 5 is realized by software, firmware, etc. However, this is merely an example, and some of the components in the radar signal processing device 5 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, etc.

[0024] The radar device shown in Fig. 1 is installed near the front of a vehicle, for example, as shown in Fig. 4, and the target is, for example, another vehicle traveling to the right front of the vehicle. In the example of Fig. 4, N Ｒｘ Receiving antennas 3-1 to 3-N Ｒｘ In the example of FIG. 4, the transmitting antennas 2-1 to 2-N are installed in a row. Ｔｘ In the example of FIG. 4, the receiving antennas 3-1 to 3-N Ｒｘ In the direction in which the receiving antennas 3-j (j=1, . . . , N Ｒｘ ) the position error Δd ｊ In the example of Fig. 4, the vehicle on which the radar device is installed is traveling at a constant speed, and the target vehicle is traveling with an unknown acceleration. Fig. 4 shows the relationship between the vehicle on which the radar device is installed and the target, and the position error Δd of the receiving antenna 3-j. ｊ FIG.

[0025] In FIG. 4, the position error Δd of the receiving antenna 3-j ｊ The figure shows an example in which the position error Δd of the receiving antenna 3-j occurs randomly. ｊ Even if no signal is generated, as shown in FIG. 5, the signal is transmitted to the transmitting antenna 2-i (i=1, . . . , N Ｔｘ ) position error Δd ｉ occurs, the position error Δd of the receiving antenna 3-j is ｊ 5 shows the position error Δd ｉ FIG. Ｔｘ Transmitting antennas 2-1 to 2-N Ｔｘ are arranged in a row at intervals of 2λ, which is the wavelength of the pulse of the transmission signal. However, in the example of FIG. 5, the position error Δd ｉ occurs randomly.

[0026] Next, the operation of the radar device shown in Fig. 1 will be described. The transmitter 1 repeatedly generates pulses as a transmission signal and transmits the pulses to the transmitting antennas 2-1 to 2-N. Ｔｘ The transmitter 1 outputs to the transmitting antenna 2-i (i=1, . . . , N Ｔｘ ) is output at intervals of time T, as shown in FIG. 6. FIG. 6 is an explanatory diagram showing the timing of pulses output from the transmitter 1 to each of the three transmitting antennas 2-1 to 2-3. In the example of FIG. 6, the timing at which a pulse is output from the transmitter 1 to the transmitting antenna 2-1 is shifted by time τ from the timing at which a pulse is output from the transmitter 1 to the transmitting antenna 2-2. Also, the timing at which a pulse is output from the transmitter 1 to the transmitting antenna 2-2 is shifted by time τ from the timing at which a pulse is output from the transmitter 1 to the transmitting antenna 2-3. The transmitting antenna 2-i radiates the pulse output from the transmitter 1 toward a target.

[0027] Transmitting antenna 2-i (i=1, . . . , N Ｔｘ ) is reflected by the target. The pulse after reflection by the target is transmitted to the receiving antenna 3-j (j=1, . . . , N Ｒｘ) The receiving antenna 3-j receives the pulse reflected by the target and outputs the received pulse signal to the receiver 4. The receiver 4 demodulates the received signal output from the receiving antenna 3-j and converts the demodulated received signal from an analog signal to a digital signal. The receiver 4 outputs the received signal s(i, j, h), which is a digital signal, to the radar signal processing device 5, as shown in the following equation (1):

[0028]

[0029] In equation (1), h is the hit number of the pulse emitted from the transmitting antenna 2-i. Here, for convenience of explanation, it is assumed that h=0, 1, ..., H-1. H is an integer equal to or greater than 2. i is a variable indicating the transmitting antenna 2-i that emitted the pulse. Here, for convenience of explanation, it is assumed that i=0, 1, ..., N ＴＸ -1. However, this is just an example, and i=1,...,N ＴＸ j is a variable indicating the receiving antenna 3-j that received the pulse. For convenience of explanation, j=0, 1, ..., N ＲＸ -1. However, this is just an example, and j=1,...,N ＲＸ It may be: ０ is the initial velocity of the target in the line of sight, β is the acceleration of the target in the line of sight, and θ is the direction in which the target is located measured from the boresight. ｃ is the central wavenumber.

[0030] In formula (1), k ｃ βhT hT is the phase disturbance term of the received signal s(i, j, h) caused by the target's line-of-sight acceleration β. ｃ sinθΔd ｉ is the position error Δd of the transmitting antenna 2-i ｉ is the phase disturbance term of the received signal s(i, j, h) caused by ｃ ・(2v ０ +βiτ)·iτ is the phase disturbance term of the received signal s(i, j, h) caused by the target's line-of-sight acceleration β. ｃ2β·hT·iτ is a phase disturbance term of the received signal s(i, j, h) caused by the target's acceleration β in the line of sight direction.

[0031] The four phase disturbance terms are errors ΔT that follow different Gaussian distributions. ｈ , ΔD ｉ , Δτ ｉ , Δe ｈｉ Using the above, approximation can be performed as shown in the following equations (2) to (5). However, the error ΔT ｈ , ΔD ｉ , Δτ ｉ , Δe ｈｉ is ΔT ｈ ~N(0, σ Ｔ ２ ), ΔD ｉ ~N(0, σ Ｄ ２ ), Δe ｈｉ ~N(0, σ ｅ ２ ) shall be in accordance with the

[0032]

[0033] By substituting equations (2) to (5) into equation (1), the received signal s(i, j, h) can be approximated as shown in equation (6) below.

[0034]

[0035] In a two-dimensional RISR (Reiterative Super Resolution) including multiple error models, if the dynamic error component of the receiving antenna 3-j can be ignored, the two-dimensional RISR can be modeled as shown in the following equations (7) to (16).

[0036]

[0037] Bold y∈C ＮＲｘ×１ is N Ｒｘ receiving antennas 3-j (j=0, 1, . . . , N ＲＸ The received signal vector (s(i, 0, h), ..., s(i, N Ｒｘ -1, h)). Bold A∈C Ｎｖ×Ｍａis a steering vector a corresponding to Ma (Ma is an integer equal to or greater than 2) angular grids. ｍ，ｎ The steering vector a is an array manifold matrix in which the vectors are arranged in the column direction. ｍ，ｎ is the receiving antenna 3-1 to 3-N in a certain direction. Ｒｘ The values ​​indicated by the bold x are the amplitude ratio or phase difference between the signals, and are known values ​​in the radar signal processing device 5. １，１ , ..., x ｍ，ｎ , ..., x Ｍａ，Ｎｖ ] is the angle grid m (m=1,...,M ａ ), the velocity grid is n (n=1,...,N ｖ ) is the signal amplitude vector that indicates the signal amplitude of the grid where Q is the noise vector. （１） ∈C Ｎｖ×Ｍａ is a static array error matrix that lists the steering vector errors caused by the target acceleration. （２） ∈C Ｎｖ×Ｍａ is the position error Δd of the receiving antenna 3-j ｊ is a static array error matrix that lists the steering vector errors caused by （３） ∈C Ｎｖ×Ｍａ is a static array error matrix that lists steering vector errors caused by coupling errors. ａ is the number of angular grids in the two-dimensional spectrum including the angular spectrum indicating the direction in which the target exists and the velocity spectrum indicating the velocity of the target, and N ｖ is the velocity grid number in the two-dimensional spectrum.

[0038]

[0039]

[0040] 7 is a flowchart showing a radar signal processing method, which is a processing procedure of the radar signal processing device 5. The received signal acquisition unit 11 of the radar signal processing device 5 receives a signal from the receiver 4 via the receiving antenna 3-j (j=0, . . . , N Ｒｘ Received signal s(i, j, h) of N (i, j, h) is acquired (step ST1 in FIG. 7). ＲｘFor the receiving antennas, 3-1 to 3-N Ｒｘ However, for the sake of convenience, j=0, . . . , N Ｒｘ The received signal acquisition unit 11 outputs the received signal s(i, j, h) to the spectrum calculation unit 12.

[0041] The spectrum calculation unit 12 acquires the received signal s(i, j, h) from the received signal acquisition unit 11. Based on the received signal s(i, j, h), the spectrum calculation unit 12 calculates a two-dimensional spectrum x ｍ，ｎ Calculate the initial value of hat (step ST2 in FIG. 7). For electronic filing, the character "x" is used in the text of the specification. ｍ，ｎ Since the symbol "^" cannot be added above ", ｍ，ｎ Specifically, the spectrum calculation unit 12 calculates the received signal vector y=(s(i, 0, h), ..., s(i, N)) of the array antenna as shown in the following equation (17). Ｒｘ −1, h)) and the steering vector a shown in equation (13) ｍ，ｎ and the two-dimensional spectrum x ｍ，ｎ The spectrum calculation unit 12 calculates the initial value of the two-dimensional spectrum x ｍ，ｎ The initial value of hat is output to the spectrum update unit 13 .

[0042]

[0043] The spectrum update unit 13 receives the two-dimensional spectrum x ｍ，ｎ The spectrum update unit 13 obtains the initial value of the hat. The spectrum update unit 13 calculates the nonlinear components contained in the velocity spectrum of the two-dimensional spectrum and the nonlinear components contained in the angle spectrum of the two-dimensional spectrum for the receiving antennas 3-1 to 3-N. Ｒｘ and the position error of the two-dimensional spectrum x ｍ，ｎ The spectrum update unit 13 updates the two-dimensional spectrum x ｍ，ｎ When the hat update process is completed, the updated two-dimensional spectrum x ｍ，ｎ The hat is output to the display device 6, for example.

[0044] Hereinafter, the two-dimensional spectrum x ｍ，ｎ The hat updating process will be specifically described. First, the first update processing unit 13a of the spectrum updating unit 13 calculates the expected value E[q ｍ，ｎ （１） q ｍ，ｎ （１）Ｈ ] is calculated. ａ and n=1, . . . , N ｖ is.

[0045] In formulas (18) and (19), 1 Ｋ×Ｌ is a K × L matrix with all elements being 1, and I Ｋ is a K×K identity matrix.

[0046] The second update processing unit 13b of the spectrum update unit 13 calculates the expected value E[q ｍ，ｎ （２） q ｍ，ｎ （２）Ｈ ] is calculated.

[0047]

[0048] The third update processing unit 13c of the first update processing unit 13a calculates the expected value E[q ｍ，ｎ （３） q ｍ，ｎ （３）Ｈ ] is calculated.

[0049]

[0050] Next, the first update processing unit 13a calculates the expected value E[q ｍ，ｎ （１） q ｍ，ｎ （１）Ｈ ] is used to calculate the array error matrix Q （１） The approximate analytical solution E[yx ｍ，ｎ ＊] and approximate analytical solution E[yy Ｈ Specifically, the first update processing unit 13a calculates the two-dimensional spectrum x calculated by the spectrum calculation unit 12. ｍ，ｎ The initial value of hat is p ｍ，ｎ By substituting into equation (24), the approximate analytical solution E[yx ｍ，ｎ ＊ ]. The first update processing unit 13a also calculates the two-dimensional spectrum x ｍ，ｎ The initial value of hat is p ｍ，ｎ By substituting into equation (27), the correlation matrix R ｘｘ Then, the first update processing unit 13a calculates the correlation matrix R ｘｘ By substituting into equation (25), the approximate analytical solution E[yy Ｈ ] is calculated.

[0051]

[0052] The second update processing unit 13b calculates the expected value E[q ｍ，ｎ （２） q ｍ，ｎ （２）Ｈ ] is used to calculate the array error matrix Q （２） The approximate analytical solution E[yx ｍ，ｎ ＊ ] and approximate analytical solution E[yy Ｈ Specifically, the second update processing unit 13b calculates the two-dimensional spectrum x calculated by the spectrum calculation unit 12. ｍ，ｎ The initial value of hat is p ｍ，ｎ By substituting into equation (29), the approximate analytical solution E[yx ｍ，ｎ ＊ ]. The second update processing unit 13b calculates the correlation matrix R ｘｘ By substituting into equation (30), the approximate analytical solution E[yy Ｈ ] is calculated.

[0053]

[0054] The third update processing unit 13c calculates the expected value E[q ｍ，ｎ （３） q ｍ，ｎ （３）Ｈ ] is used to calculate the array error matrix Q （３） The approximate analytical solution E[yx ｍ，ｎ ＊ ] and approximate analytical solution E[yy Ｈ Specifically, the third update processing unit 13c calculates the two-dimensional spectrum x calculated by the spectrum calculation unit 12. ｍ，ｎ The initial value of hat is p ｍ，ｎ By substituting into equation (32), the approximate analytical solution E[yx ｍ，ｎ ＊ ]. The third update processing unit 13c calculates the correlation matrix R ｘｘ By substituting into equation (33), the approximate analytical solution E[yy Ｈ ] is calculated.

[0055]

[0056] Here, the approximate analytical solution E[yy Ｈ ] and the approximate analytical solution E[yy Ｈ ] and the approximate analytical solution E[yy Ｈ ], it can be seen that the structures as block matrices are different. Since the structures of the block matrices are different, the array error matrix Q （１） and the array error matrix Q （２） and the array error matrix Q （３） The optimal weight w of the RISR when all of the error components are included in the RISR model. ｍ，ｎ （１） Hat, w ｍ，ｎ （２） Hat, w ｍ，ｎ （３） Calculating hat is not easy.

[0057] Therefore, the first update processing unit 13a updates the array error matrix Q （１） By including the error component of ｍ，ｎ （１） Specifically, the optimal weight w ｍ，ｎ （１） When the calculation of hat is the first calculation, the first update processing unit 13a updates the calculated correlation matrix R ｘｘ By substituting into equation (36), the optimal weight w ｍ，ｎ （１） The optimal weight w is calculated by the first update processing unit 13a. ｍ，ｎ （１） If the calculation of hat is the second or subsequent calculation, the first update processing unit 13a updates the two-dimensional spectrum x previously updated by the third update processing unit 13c in step ST5 described later. ｍ，ｎ Hat p ｍ，ｎ By substituting into equation (27), the correlation matrix R ｘｘ The two-dimensional spectrum x ｍ，ｎ The updating of the hat will be described later. The first updating unit 13a updates the calculated correlation matrix R ｘｘ By substituting into equation (36), the optimal weight w ｍ，ｎ （１） The first update processing unit 13a calculates the optimal weight w as shown in the following equation (37). ｍ，ｎ （１） Using the hat, the two-dimensional spectrum x ｍ，ｎ The hat is updated (step ST3 in FIG. 7).

[0058] In equation (35), α is a partial constraint coefficient that takes a value between 0 and 1.

[0059] Next, the second update processing unit 13b updates the array error matrix Q （２） By including the error component of ｍ，ｎ （２）Specifically, the second update processing unit 13b calculates the two-dimensional spectrum x after updating by the first update processing unit 13a. ｍ，ｎ Hat p ｍ，ｎ By substituting into equation (27), the correlation matrix R ｘｘ The second update processing unit 13b calculates the calculated correlation matrix R ｘｘ By substituting into equation (39), the optimal weight w ｍ，ｎ （２） The second update processing unit 13b calculates the optimal weight w as shown in the following equation (40). ｍ，ｎ （２） Using hat, the two-dimensional spectrum x after updating by the first updating unit 13a is ｍ，ｎ The hat is further updated (step ST4 in FIG. 7).

[0060]

[0061] Next, the third update processing unit 13c updates the array error matrix Q （３） By including the error component of ｍ，ｎ （３） Specifically, the third update processing unit 13c calculates the two-dimensional spectrum x after updating by the second update processing unit 13b. ｍ，ｎ Hat p ｍ，ｎ By substituting into equation (27), the correlation matrix R ｘｘ The third update processing unit 13c calculates the calculated correlation matrix R ｘｘ By substituting into equation (42), the optimal weight w ｍ，ｎ （３） The third update processing unit 13c calculates the optimal weight w as shown in the following equation (43). ｍ，ｎ （３） Using the hat, the two-dimensional spectrum x after updating by the second updating unit 13b is ｍ，ｎ The hat is further updated (step ST5 in FIG. 7).

[0062]

[0063] The spectrum update unit 13 updates the two-dimensional spectrum x ｍ，ｎ If the hat has not converged (NO in step ST6 in FIG. 7), the update process of steps ST3 to ST5 is repeated. Each time the update process of steps ST3 to ST5 is repeated, the two-dimensional spectrum x ｍ，ｎ The accuracy of the hat is improved. The spectrum update unit 13 updates the two-dimensional spectrum x ｍ，ｎ If the hat has converged (step ST6 in FIG. 7: YES), the two-dimensional spectrum x ｍ，ｎ The two-dimensional spectrum x is output to, for example, the display device 6. ｍ，ｎ The convergence condition of the hat is not particularly limited, but for example, the two-dimensional spectrum x before and after updating ｍ，ｎ If the difference between the hats is equal to or smaller than the threshold, the updated two-dimensional spectrum x ｍ，ｎ On the other hand, the two-dimensional spectrum x before and after the update ｍ，ｎ If the difference between the hats is greater than the threshold, the updated two-dimensional spectrum x ｍ，ｎ It can be determined that the hat has not converged.

[0064] The display device 6 receives the updated two-dimensional spectrum x from the radar signal processing device 5. ｍ，ｎ The display device 6 displays the updated two-dimensional spectrum x as shown in FIG. ｍ，ｎ The hat is displayed on a display (not shown). ｍ，ｎ 13 is an explanatory diagram showing an example of hat display. In Fig. 13, the horizontal axis represents angle and the vertical axis represents velocity. Grids representing the direction in which a target exists and the velocity of the target are displayed in black in the figure.

[0065] In the first embodiment described above, a plurality of receiving antennas 3-1 to 3-N Ｒｘthe spectrum calculation unit 12 that calculates an initial value of a two-dimensional spectrum indicating the direction in which the target exists and the velocity of the target based on the received signals acquired by the received signal acquisition unit 11, and a spectrum updating unit 13 that updates the two-dimensional spectrum based on a nonlinear component included in the velocity spectrum in the two-dimensional spectrum and a position error of the receiving antenna included in the angle spectrum in the two-dimensional spectrum. Therefore, when there is an unknown position error in the installation position of the receiving antenna 3-j, the radar signal processing device 5 can calculate not only the direction in which the target exists but also the velocity of the target.

[0066] In the second embodiment, the spectrum update unit 14 updates the optimal weight w ｍ，ｎ （１） Using the hat, the two-dimensional spectrum x ｍ，ｎ The process of updating the hat is performed, and the optimal weight w ｍ，ｎ （２） Using the hat, the two-dimensional spectrum x ｍ，ｎ The process of updating the hat is performed, and the optimal weight w ｍ，ｎ （３） Using the hat, the two-dimensional spectrum x ｍ，ｎ The radar signal processing device 5 that performs the process of updating the hat will now be described.

[0067] Fig. 8 is a configuration diagram showing a radar device including a radar signal processing device 5 according to embodiment 2. In Fig. 8, the same reference numerals as in Fig. 1 indicate the same or corresponding parts, and detailed description thereof will be omitted. Fig. 9 is a hardware configuration diagram showing the hardware of the radar signal processing device 5 according to embodiment 2. In Fig. 9, the same reference numerals as in Fig. 2 indicate the same or corresponding parts, and detailed description thereof will be omitted. The radar signal processing device 5 shown in Fig. 8 includes a received signal acquisition unit 11, a spectrum calculation unit 12, and a spectrum update unit 14.

[0068] The spectrum updating unit 14 is realized by, for example, the spectrum updating circuit 24 shown in FIG. 9 . The spectrum updating unit 14 includes a first updating unit 14 a, a second updating unit 14 b, and a third updating unit 14 c. The spectrum updating unit 14 acquires an initial value of the two-dimensional spectrum from the spectrum calculating unit 12. The spectrum updating unit 14 calculates a first update count, which is the number of update processes for the two-dimensional spectrum based on the nonlinear components, based on the nonlinear components included in the velocity spectrum of the two-dimensional spectrum. The spectrum updating unit 14 repeatedly performs the update process for the two-dimensional spectrum based on the nonlinear components the first update count.

[0069] The spectrum update unit 14 receives the signals from the receiving antennas 3-1 to 3-N. Ｒｘ Based on the position error of the receiving antennas 3-1 to 3-N Ｒｘ The spectrum update unit 14 calculates a second update count, which is the number of update processes for the two-dimensional spectrum based on the position error. The spectrum update unit 14 repeatedly performs the update process for the two-dimensional spectrum based on the position error the second update count. The spectrum update unit 14 calculates a third update count, which is the number of update processes for the two-dimensional spectrum based on the coupling error, based on the coupling error. The spectrum update unit 14 repeatedly performs the update process for the two-dimensional spectrum based on the coupling error the third update count. The spectrum update unit 14 calculates the second update count, which is the number of update processes for the two-dimensional spectrum based on the coupling error, the third update count. ｍ，ｎ When the hat update process is completed, the updated two-dimensional spectrum x ｍ，ｎ The hat is output to the display device 6, for example.

[0070] The first update processing unit 14a acquires an initial value of the two-dimensional spectrum from the spectrum calculation unit 12. The first update processing unit 14a calculates a first number of updates based on the magnitude of the nonlinear component caused by the acceleration of the target and the magnitude of the nonlinear component caused by the variation in the pulse transmission interval. The first update processing unit 14a repeatedly performs the update process of the two-dimensional spectrum based on the nonlinear component the first number of updates. The update process of the two-dimensional spectrum by the first update processing unit 14a is the same as the update process of the two-dimensional spectrum by the first update processing unit 13a shown in FIG. 1. The first update processing unit 14a outputs the updated two-dimensional spectrum to the second update processing unit 14b.

[0071] The second update processing unit 14b acquires the updated two-dimensional spectrum from the first update processing unit 14a. The second update processing unit 14b updates the two-dimensional spectrum of the receiving antennas 3-1 to 3-N included in the angular spectrum. Ｒｘ The second update processing unit 14b calculates a second update count based on the position error. The second update processing unit 14b repeatedly performs the update process of the two-dimensional spectrum based on the position error the second update count. The update process of the two-dimensional spectrum by the second update processing unit 14b is the same as the update process of the two-dimensional spectrum by the second update processing unit 13b shown in FIG. 1. The second update processing unit 14b outputs the updated two-dimensional spectrum to the third update processing unit 14c.

[0072] The third update processor 14c acquires the updated two-dimensional spectrum from the second update processor 14b. The third update processor 14c calculates the third number of updates based on the coupling error. The third update processor 14c repeatedly performs the update process of the two-dimensional spectrum based on the coupling error the third number of updates. The update process of the two-dimensional spectrum by the third update processor 14c is the same as the update process of the two-dimensional spectrum by the third update processor 13c shown in FIG. 1. The third update processor 14c outputs the updated two-dimensional spectrum to, for example, the display device 6.

[0073] 8, it is assumed that the received signal acquisition unit 11, the spectrum calculation unit 12, and the spectrum update unit 14, which are components of the radar signal processing device 5, are each realized by dedicated hardware as shown in Fig. 9. That is, it is assumed that the radar signal processing device 5 is realized by a received signal acquisition circuit 21, a spectrum calculation circuit 22, and a spectrum update circuit 24. Each of the received signal acquisition circuit 21, the spectrum calculation circuit 22, and the spectrum update circuit 24 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

[0074] The components of the radar signal processing device 5 are not limited to those realized by dedicated hardware, and the radar signal processing device 5 may be realized by software, firmware, or a combination of software and firmware. When the radar signal processing device 5 is realized by software, firmware, or the like, a program for causing a computer to execute the respective processing procedures of the received signal acquisition unit 11, the spectrum calculation unit 12, and the spectrum update unit 14 is stored in a memory 31 shown in Fig. 3. Then, a processor 32 shown in Fig. 3 executes the program stored in the memory 31.

[0075] 9 shows an example in which each of the components of the radar signal processing device 5 is realized by dedicated hardware, while Fig. 3 shows an example in which the radar signal processing device 5 is realized by software, firmware, etc. However, this is merely an example, and some of the components in the radar signal processing device 5 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, etc.

[0076] Next, the operation of the radar device shown in Fig. 8 will be described. However, apart from the spectrum update unit 14 of the radar signal processing device 5, the radar device is the same as that shown in Fig. 1. Therefore, only the operation of the spectrum update unit 14 will be described here.

[0077] The first update processing unit 14a calculates the magnitude NC of the nonlinear component caused by the gaze direction acceleration β of the target, for example, as shown in the following equation (44): １ and the nonlinear component NC due to variations in the pulse transmission interval. ２ and the magnitude of the first update count UPC １ Calculate.

[0078] In formula (44), PC １ , PC ２ are proportionality constants, which may be stored in the internal memory of the first update processing unit 14 a or may be provided from outside the radar signal processing device 5 .

[0079] The second update processing unit 14b calculates the angular spectrum of the receiving antenna 3-j (j=1, . . . , N) included in the angular spectrum as shown in, for example, the following equation (45) or equation (46): Ｒｘ ) position error Δd ｊ Based on this, the second update count UPC ２ Calculate.

[0080] In equations (45) and (46), PC ３ is a proportionality constant, which may be stored in the internal memory of the second update processing unit 14 b, or may be provided from outside the radar signal processing device 5, for example.

[0081] The third update processing unit 14c calculates the third update count UPC based on the coupling error CE, for example, as shown in the following equation (47): ３ Calculate.

[0082] In equation (47), PC ４ is a proportionality constant, which may be stored in the internal memory of the third update processing unit 14 c, or may be provided from outside the radar signal processing device 5, for example.

[0083] The first update processing unit 14 a, the second update processing unit 14 b, and the third update processing unit 14 c respectively update the two-dimensional spectrum x ｍ，ｎ The update processing of hats is performed in order. However, the number of update processes in the first update processing unit 13a, the second update processing unit 13b, and the third update processing unit 13c shown in Fig. 1 is the same, whereas the number of update processes in the first update processing unit 14a, the second update processing unit 14b, and the third update processing unit 14c is different from one another. That is, the first update processing unit 14a performs the first update count UPC １ Only the two-dimensional spectrum x based on the nonlinear component ｍ，ｎ The second update processing unit 14b performs update processing of the second update count UPC. ２ The position error Δd ｊ Two-dimensional spectrum x based on ｍ，ｎ The third update processing unit 14c performs update processing of the third update count UPC. ３ The two-dimensional spectrum x based on the coupling error CE is ｍ，ｎ Performs hat update processing.

[0084] In the second embodiment described above, the spectrum update unit 14 calculates the first update count, which is the number of update processes for the two-dimensional spectrum based on the nonlinear components, based on the nonlinear components included in the velocity spectrum, and updates the received signal from the receiving antenna 3-j (j=1, . . . , N Ｒｘ) based on the position error of the receiving antenna 3-j, calculates a second update count, which is the number of update processes for the two-dimensional spectrum based on the position error of the receiving antenna 3-j, and calculates a third update count, which is the number of update processes for the two-dimensional spectrum based on the coupling error, based on the coupling error. The radar signal processing device 5 shown in FIG. 8 is configured so that the spectrum update unit 14 repeatedly performs the update process for the two-dimensional spectrum based on the nonlinear component the first update count, repeatedly performs the update process for the two-dimensional spectrum based on the position error of the receiving antenna 3-j the second update count, and repeatedly performs the update process for the two-dimensional spectrum based on the coupling error the third update count. Therefore, like the radar signal processing device 5 shown in FIG. 1, when there is an unknown position error in the installation position of the receiving antenna 3-j, the radar signal processing device 5 shown in FIG. 8 can calculate not only the direction in which the target exists but also the speed of the target, and can optimize the number of update processes.

[0085] Embodiment 3. In the first and second embodiments, as an application example of the radar signal processing device 5, as shown in Fig. 4, a vehicle on which a radar device is installed travels at a constant speed, and a target vehicle travels with unknown acceleration. However, this is merely an example, and as an application example of the radar signal processing device 5, as shown in Fig. 10, a vehicle on which a radar device is installed travels with acceleration, and a target vehicle travels at a constant speed, may also be used. In the example of Fig. 10, N Ｒｘ Receiving antennas 3-1 to 3-N Ｒｘ In the example of FIG. 10, the transmitting antennas 2-1 to 2-N are arranged in a row. Ｔｘ In the example of FIG. 10, the receiving antenna 3-j (j=1, . . . , N Ｒｘ ) Position error Δd ｊ 10 shows the relationship between the vehicle on which the radar device is installed and the target, and the position error Δd of the receiving antenna 3-j. ｊ10 , the radar signal processing device 5 can calculate a two-dimensional spectrum indicating the direction in which a target exists and the speed of the target when there is an unknown position error in the installation position of the receiving antenna 3-j, as in the first and second embodiments.

[0086] As an application example of the radar signal processing device 5, as shown in Fig. 11, both the vehicle on which the radar device is installed and the target vehicle may be traveling at a constant speed. However, in the example of Fig. 11, the transmitting antennas 2-1 to 2-N Ｔｘ 11 shows the relationship between the vehicle on which the radar device is installed and the target, and the position error Δd ｊ 11 , the radar signal processing device 5 can calculate a two-dimensional spectrum indicating the direction in which a target exists and the speed of the target when there is an unknown position error in the installation position of the receiving antenna 3-j, as in the first and second embodiments.

[0087] 12, the radar signal processing device 5 may be applied to a vehicle on which the radar device is installed traveling with an acceleration, and a target vehicle traveling with an unknown acceleration. In the example of FIG. 12, N Ｒｘ Receiving antennas 3-1 to 3-N Ｒｘ In the example of FIG. 12, transmitting antennas 2-1 to 2-N are installed in a row. Ｔｘ In the example of FIG. 12, the receiving antenna 3-j (j=1, . . . , N Ｒｘ ) Position error Δd ｊ 12 shows the relationship between the vehicle on which the radar device is installed and the target, and the position error Δd of the receiving antenna 3-j. ｊ12 , the radar signal processing device 5 can calculate a two-dimensional spectrum indicating the direction in which a target exists and the speed of the target when there is an unknown position error in the installation position of the receiving antenna 3-j, as in the first and second embodiments.

[0088] In addition, the present disclosure allows for free combination of the respective embodiments, modification of any of the components of the respective embodiments, or omission of any of the components of the respective embodiments.

[0089] The present disclosure is suitable for a radar signal processing device, a radar signal processing method, and a radar device.

[0090] 1 transmitter, 2-1 to 2-N Ｔｘ Transmitting antennas, 3-1 to 3-N Ｒｘ Receiving antenna, 4 receiver, 5 radar signal processing device, 6 display device, 11 received signal acquisition unit, 12 spectrum calculation unit, 13, 14 spectrum update unit, 13a, 14a first update processing unit, 13b, 14b second update processing unit, 13c, 14c third update processing unit, 21 received signal acquisition circuit, 22 spectrum calculation circuit, 23 spectrum update circuit, 31 memory, 32 processor.

Claims

1. A radar signal processing apparatus comprising: a reception signal acquisition unit that acquires each reception signal in a plurality of reception antennas; a spectrum calculation unit that calculates an initial value of a two-dimensional spectrum indicating a direction in which a target exists and a speed of the target based on the reception signals acquired by the reception signal acquisition unit; and a spectrum update unit that updates the two-dimensional spectrum based on a non-linear component included in a spectrum of speed in the two-dimensional spectrum and a position error of the reception antenna included in a spectrum of an angle in the two-dimensional spectrum.

2. The radar signal processing apparatus according to claim 1, wherein the spectrum update unit includes: a first update processing unit that updates the two-dimensional spectrum calculated by the spectrum calculation unit based on a non-linear component included in the spectrum of speed; a second update processing unit that updates the two-dimensional spectrum updated by the first update processing unit based on the position error of the reception antenna included in the spectrum of the angle; and a third update processing unit that updates the two-dimensional spectrum updated by the second update processing unit based on a coupling error between the non-linear component and the position error.

3. The radar signal processing apparatus according to claim 2, wherein the first update processing unit updates the two-dimensional spectrum calculated by the spectrum calculation unit based on a non-linear component caused by an acceleration of the target among the non-linear components included in the spectrum of speed.

4. The radar signal processing apparatus according to claim 2, wherein the first update processing unit updates the two-dimensional spectrum calculated by the spectrum calculation unit based on a non-linear component caused by a variation in a transmission interval of pulses transmitted from a transmission antenna among the non-linear components included in the spectrum of speed.

5. The radar signal processing apparatus according to claim 1, wherein the spectrum update unit repeatedly performs an update process of the two-dimensional spectrum until the two-dimensional spectrum converges.

6. The spectrum update unit calculates a first update count, which is the number of update processes of the two-dimensional spectrum based on the non-linear component, based on the non-linear component included in the spectrum of the speed, calculates a second update count, which is the number of update processes of the two-dimensional spectrum based on the position error of the receiving antenna, based on the position error of the receiving antenna, calculates a third update count, which is the number of update processes of the two-dimensional spectrum based on the coupling error, based on the coupling error, and repeatedly performs the update process of the two-dimensional spectrum based on the non-linear component for the number of times of the first update count, repeatedly performs the update process of the two-dimensional spectrum based on the position error of the receiving antenna for the number of times of the second update count, and repeatedly performs the update process of the two-dimensional spectrum based on the coupling error for the number of times of the third update count. The radar signal processing apparatus according to claim 1, characterized by the above.

7. A radar signal processing method, wherein a reception signal acquisition unit acquires each reception signal in a plurality of receiving antennas, a spectrum calculation unit calculates an initial value of a two-dimensional spectrum indicating a direction in which a target exists and a speed of the target based on the reception signal acquired by the reception signal acquisition unit, and a spectrum update unit updates the two-dimensional spectrum based on a non-linear component included in the spectrum of the speed in the two-dimensional spectrum and a position error of the receiving antenna included in the spectrum of the angle in the two-dimensional spectrum.

8. A radar apparatus including: a transmitting antenna that radiates a transmission signal toward a target; a plurality of receiving antennas that receive a reception signal, which is the transmission signal after being reflected by the target; a reception signal acquisition unit that acquires each reception signal in the plurality of receiving antennas; a spectrum calculation unit that calculates an initial value of a two-dimensional spectrum indicating a direction in which a target exists and a speed of the target based on the reception signal acquired by the reception signal acquisition unit; and a spectrum update unit that updates the two-dimensional spectrum based on a non-linear component included in the spectrum of the speed in the two-dimensional spectrum and a position error of the receiving antenna included in the spectrum of the angle in the two-dimensional spectrum.