Radar device, radar control method, and radar control program

Abstract

A control unit of a radar device has an acquisition unit that acquires a mixed reception signal received by a specific reception antenna. The control unit has a definition unit that defines a plurality of decoded signals in which the mixed reception signal is decoded by each code corresponding to each transmission signal. The control unit has a suppression unit. The suppression unit performs suppression processing for suppressing, in another decoded signal or a related signal related to the decoded signal, a sidelobe signal component detected in the other decoded signal in relation to a target signal component corresponding to a target transmission signal in a specific decoded signal. The suppression unit executes suppression processing in accordance with any one of the plurality of algorithms. The suppression unit selects an algorithm followed by the suppression processing on the basis of a characteristic parameter relating to the performance of each algorithm.

Description

Radar device, radar control method, radar control program Technical Field

[0001] Cross-reference of related applications

[0002] This application is based on Japanese Patent Application No. 2023-173008, filed on October 4, 2023, the contents of which are incorporated herein by reference in their entirety. Background Technology

[0003] This disclosure relates to a technique for controlling a radar device.

[0004] Patent Document 1 discloses a MIMO radar using a pseudo-random phase modulation method. Such a MIMO radar transmits signals modulated by different CDM codes from each transmitting antenna. The MIMO radar generates a decoded signal spectrum based on each CDM code for the received signal and infers sidelobe signal components from each decoded signal spectrum. The MIMO radar obtains a decoded signal spectrum with suppressed sidelobe signal components by subtracting the inferred sidelobe signal components from the decoded signal spectrum corresponding to the transmitting antenna being tested.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: US Patent No. 9952319

[0008] The technical problem that the invention aims to solve

[0009] However, various algorithms have been proposed for suppressing sidelobe signal components. The performance of each algorithm varies depending on the situation. However, Patent Document 1 does not describe a method for determining the algorithm corresponding to the situation. Summary of the Invention

[0010] The present disclosure addresses the following objective: to provide a radar device capable of determining, based on the situation, the algorithm followed by the suppression processing of sidelobe signal components. Another objective of the present disclosure is to provide a radar control method capable of determining, based on the situation, the algorithm followed by the suppression processing of sidelobe signal components. Yet another objective of the present disclosure is to provide a radar control program capable of determining, based on the situation, the algorithm followed by the suppression processing of sidelobe signal components.

[0011] The technical means disclosed herein for solving the problem will be described below. Furthermore, the symbols in parentheses within the scope of the patent claim correspond to the specific means described in the detailed embodiments below, and do not limit the technical scope of this disclosure.

[0012] The first aspect of this disclosure is a radar device, comprising:

[0013] More than one transmitting antenna;

[0014] A transmission signal generation unit generates multiple types of transmission signals modulated by different codes transmitted from the transmission antenna;

[0015] A receiving antenna that receives a mixed received signal, which is a combination of the transmitted signals reflected by the reflector; and

[0016] The control unit processes the mixed received signals.

[0017] The control unit has:

[0018] The acquisition unit acquires the mixed received signal received by a specific receiving antenna;

[0019] A definition section defines a plurality of decoded signals, which are obtained by decoding the mixed received signal with each code corresponding to each transmitted signal; and

[0020] A suppression unit performs suppression processing according to any one of a plurality of algorithms. This suppression processing suppresses sidelobe signal components detected in other decoded signals in relation to the target signal component, which is the received signal component corresponding to the transmitted signal that is the target in a particular decoded signal.

[0021] The suppression unit selects the suppression algorithm based on characteristic parameters related to the performance of each algorithm.

[0022] The second aspect of this disclosure is a radar control method executed by a processor to control a radar device, the radar device including one or more transmitting antennas, a transmitting signal generation unit, and a receiving antenna. The transmitting signal generation unit generates multiple types of transmitting signals modulated by different codes transmitted from the transmitting antennas, and the receiving antenna receives a mixed receiving signal composed of the various transmitting signals reflected by reflectors, including:

[0023] Acquire the mixed received signal received by a specific receiving antenna;

[0024] Define multiple decoded signals, which are obtained by decoding the mixed received signal with each code corresponding to each transmitted signal; and

[0025] Suppression processing is performed according to any of several algorithms. This suppression process suppresses sidelobe signal components detected in other decoded signals, or associated signals, in relation to the target signal component, which is the received signal component corresponding to the transmitted signal as the target in a particular decoded signal.

[0026] The suppression process includes:

[0027] The algorithm used for suppression processing is selected based on the characteristic parameters related to the performance of each algorithm.

[0028] The third aspect of this disclosure is a radar control program stored in a storage medium, containing commands executed by a processor to control a radar device. The radar device includes one or more transmitting antennas, a transmitting signal generation unit, and a receiving antenna. The transmitting signal generation unit generates multiple types of transmitted signals modulated by different codes transmitted from the transmitting antennas. The receiving antenna receives a mixed received signal, formed by the mixing of the transmitted signals after reflection from a reflector.

[0029] The command includes:

[0030] Acquire the mixed received signal received by a specific receiving antenna;

[0031] Define multiple decoded signals, which are obtained by decoding the mixed received signal with each code corresponding to each transmitted signal; and

[0032] Suppression processing is performed according to any of several algorithms. This suppression process suppresses sidelobe signal components detected in other decoded signals, or associated signals, in relation to the target signal component, which is the received signal component corresponding to the transmitted signal as the target in a particular decoded signal.

[0033] The suppression process includes:

[0034] The algorithm used for suppression processing is selected based on the characteristic parameters related to the performance of each algorithm.

[0035] Based on these first to third methods, the algorithms used for suppressing sidelobe signal components are selected according to the characteristic parameters upon which the performance of each algorithm depends. Since these characteristic parameters are parameters in the decoded or associated signals, the algorithm can be selected based on the reception conditions of the mixed received signals. Therefore, the algorithm used for suppressing sidelobe signal components can be determined according to the specific circumstances. Attached Figure Description

[0036] Figure 1 is a block diagram showing the overall structure of the radar device according to the first embodiment.

[0037] Figure 2 is a block diagram showing the functional structure of the control unit in the first embodiment.

[0038] Figure 3 is a diagram showing an example of the transmission signal in the first embodiment.

[0039] Figure 4 is a flowchart illustrating the radar control method in the first embodiment.

[0040] Figure 5 is a schematic diagram showing the general overview of signal processing for generating the frequency spectrum of the decoded signal from the distance cell signal.

[0041] Figure 6 is a schematic diagram illustrating the sidelobe suppression treatment.

[0042] Figure 7 is a diagram showing an example of a frequency spectrum used to illustrate the definition of the SN ratio.

[0043] Figure 8 is a schematic diagram illustrating an example of the algorithm.

[0044] Figure 9 is a schematic diagram illustrating another example of the algorithm.

[0045] Figure 10 is a schematic diagram showing the difference between the case where sidelobe signal components were suppressed and the case where they were not suppressed. Detailed Implementation

[0046] Hereinafter, several embodiments of the present disclosure will be described based on the accompanying drawings. Furthermore, in each embodiment, repeated descriptions may be omitted by using the same symbols to denote corresponding structural elements. Additionally, where only a portion of the structure is described in each embodiment, the structures of other previously described embodiments can be applied to the other parts of that structure. Furthermore, not only combinations of structures explicitly shown in the descriptions of each embodiment are permitted, but structures from multiple embodiments can be partially combined with each other, even if not explicitly shown, provided there are no particular obstacles to such combinations.

[0047] (First Implementation)

[0048] The first embodiment of this disclosure will be described using Figures 1 to 10. The radar device 1 is mounted, for example, on a moving body such as a vehicle. The radar device 1 transmits a transmission signal to the outside world, receives the transmission signal reflected by an object as a received signal, and detects target information such as the distance to the target (which is the object reflecting the transmission signal), the relative speed with the target, and the target's azimuth.

[0049] Target information output from radar device 1 is input to the vehicle ECU (Electronic Control Unit) via vehicle networks such as CAN (Control Area Network) and Ethernet. Based on the acquired target information, the vehicle ECU performs various processes for autonomous driving and advanced driver assistance.

[0050] As a type of target information-based processing, there are collision avoidance processing and warning processing. Collision avoidance processing is a vehicle control process that uses the braking system, steering system, etc., to avoid collisions with targets based on target information. Warning processing is a process that warns the driver of the possibility of a collision with a target based on target information.

[0051] As shown in Figure 1, the radar device 1 of this embodiment includes a transmission signal generation unit 2, multiple transmission circuits 3, multiple transmission antennas TX, multiple receiving antennas RX, multiple receiving circuits 4, and a control unit 100. The radar device 1 is a so-called MIMO (Multiple-Input-Multiple-Output) radar that virtually increases the number of receiving antennas RX to more than the actual number by transmitting transmission signals from multiple transmission antennas TX.

[0052] The transmit signal generation unit 2 acquires a control signal from the control unit 100 and generates a modulated signal based on the control signal. This generated signal is, for example, a chirp signal whose frequency varies with time (see Figure 3). The generated signal is distributed and output to each channel of the transmit circuit 3 and the receive circuit 4. For each transmit channel corresponding to each transmit antenna TX, the transmit signal generation unit 2 outputs a generated signal with pseudo-random phase modulation using different codes as the transmit signal output. This modulation method is also called code division multiplexing (CDM). Furthermore, as shown in Figure 3, in this embodiment, it is assumed that the chirp transmission time, center frequency, and frequency band of the transmit signals transmitted from different transmit antennas TX are substantially the same. Additionally, in Figure 3, the transmit signals transmitted from two different transmit antennas TX are represented by different line types, namely solid lines and dashed lines.

[0053] In this embodiment, a transmission signal with phase modulation by a different code is transmitted from each of the plurality of transmitting antennas TX to the outside world. Furthermore, the signal output to the receiving circuit 4 from the generated signal is referred to as the local signal below.

[0054] The transmitting circuit 3 and the receiving circuit 4 are both primarily composed of semiconductor integrated circuit devices such as MMICs (Monolithic Microwave Integrated Circuits). The transmitting circuit 3 is connected to the transmitting antenna TX and outputs a transmitted signal to the transmitting antenna TX. The transmitting circuit 3 has the same number of amplifiers 30 as the connected transmitting antenna TX. The amplifiers 30 amplify the transmitted signal output from the transmitting signal generation unit 2 and output it to the corresponding transmitting antenna TX.

[0055] The transmitting antenna TX converts the electrical signal supplied by the transmitting signal generation unit 2, which serves as the transmitting signal, into a radio wave signal and transmits it to the outside. In this embodiment, 12 transmitting antennas TX are provided. Furthermore, when distinguishing each transmitting antenna TX individually below, it will be referred to as transmitting antenna TXn (n is a natural number from 1 to 12). 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 antenna elements in a planar shape. The antenna elements are arranged opposite to the ground plane on the side of a dielectric substrate on one side of which the ground plane is provided. The multiple antenna elements are connected in series, for example, via power supply lines that supply electrical signals.

[0056] The receiving antenna RX receives a radio wave signal that includes the transmitted signal reflected by a target, which is a reflector in the outside world, as the received signal. Multiple receiving antennas RX respectively receive a signal that is a mixture of the received signals corresponding to the respective transmitted signals from multiple transmitting antennas TX. Hereinafter, this mixed signal received by each receiving antenna RX will be referred to as the mixed received signal. Furthermore, the components of the mixed received signal that correspond to the respective transmitted signals from the multiple transmitting antennas TX will be referred to as the received signal components.

[0057] The receiving antenna RX converts the received signal, which is a radio wave signal, into an electrical signal and outputs it to the corresponding receiving circuit 4. The receiving antenna RX, for example, is a patch antenna, similar to the transmitting antenna TX, consisting of at least one antenna element connected in series via a power supply line.

[0058] The receiving circuit 4 is connected to the receiving antenna RX and acquires the received signal received by the receiving antenna RX for each receiving channel corresponding to each receiving antenna RX. The receiving circuit 4 has the same number of amplifiers 40 and signal mixing units 41 as the connected receiving antennas RX.

[0059] Amplifier 40 amplifies the received signal received by the receiving antenna and outputs it to signal mixing unit 41. Signal mixing unit 41 generates a beat frequency signal that mixes the local signal from the transmit signal generation unit 2 and the received signal. The generated beat frequency signal becomes an interference signal representing the frequency difference between the received signal and the local signal. After the beat frequency signal is filtered out by a low-pass filter (not shown) to remove high-frequency components that deviate from the frequency difference between the received signal and the local signal, it is output to control unit 100.

[0060] The control unit 100 is connected to the signal generation unit 2 and the receiving circuit 4, for example, via at least one of a LAN (Local Area Network) line, a wiring harness, an internal bus, and a wireless communication line. The control unit 100 is configured to include at least one dedicated computer.

[0061] The dedicated computer constituting the control unit 100 may be a radar ECU (Electronic Control Unit) specifically for controlling the radar device 1. The dedicated computer constituting the control unit 100 may be a radar control ECU that coordinates the control of multiple radar devices 1 mounted on a mobile body. The dedicated computer constituting the control unit 100 may be a sensor control ECU that coordinates the control of multiple sensors, including the radar device 1 and other sensors such as LiDAR (Light Detection and Ranging / Laser Imaging Detection and Ranging).

[0062] Each dedicated computer constituting the control unit 100 has at least one memory 101 and a processor 102. The memory 101 is a non-transitory physical storage medium, such as semiconductor memory, magnetic media, and optical media, that non-transitorily stores programs and data that can be read by the computer. The storage here can be the accumulation of data that is maintained even when the vehicle is started and turned off, or it can be temporary storage where the data is erased after the vehicle is started and turned off. The processor 102 includes, for example, at least one of the following as its core: CPU (Central Processing Unit), GPU (Graphics Processing Unit), RISC (Reduced Instruction Set Computer) - CPU, DFP (Data Flow Processor), and GSP (Graphics Streaming Processor).

[0063] In the control unit 100, the processor 102 executes multiple commands contained in the radar control program stored in the memory 101, which serves as a storage medium, in order to control the radar device 1. Thus, the control unit 100 constructs multiple functional blocks for controlling the radar device 1. As shown in FIG2, the multiple functional blocks constructed in the control unit 100 include an acquisition block 110, a definition block 120, a suppression block 130, and an output block 140. Furthermore, these functional blocks, as functional units, can also be referred to as an acquisition unit, a definition unit, a suppression unit, and an output unit, respectively.

[0064] Through the coordination of blocks 110, 120, 130, and 140, the control unit 100 controls the radar device 1 to execute the radar control method according to the radar control flow shown in Figure 4. This radar control flow is repeatedly executed during the startup of the radar device 1. This radar control flow is executed, for example, for each receiving channel, and is considered a cycle as one execution for all receiving channels. Furthermore, each "S" in this radar control flow represents multiple steps executed by multiple commands contained in the radar control program.

[0065] First, in S10, acquisition block 110 acquires the mixed received signal. The mixed received signal is a beat frequency signal that combines the local signal from the signal generation unit with the received signal from the receiving antenna RX. The beat frequency signal is an interference signal that represents the frequency difference between the received signal and the local signal. The mixed received signal is acquired as a digitized time signal after being sampled by the A / D converter at specified time intervals.

[0066] In the subsequent S20, definition block 120 performs Fast Fourier Transform (FFT) processing on the mixed received signal. Thus, definition block 120 obtains the range spectrum of each chirp in the mixed received signal. The obtained range spectrum represents the frequency spectrum of the peak corresponding to the distance to the target, and is discrete range data containing the signal strength information of each unit (range unit) corresponding to the distance. Subsequently, as shown in Figure 5, N will be processed by FFT... c N samples, each chirping. s The data was converted into distance data, and N values ​​of specific distance units were extracted. c The data of each sample is recorded as the range cell signal R. Here, the data derived from the transmitted signal from the transmitting antenna TXn, and the code C... txn The encoded received signal component is set to P. n The range unit signal R before decoding serves as the received signal component C from each transmitting antenna TX before decoding. txn P n The sum of these can be defined by the following mathematical formula (1).

[0067] [Mathematical Expression 1]

[0068]

[0069] In S30, definition block 120 defines the decoded signal corresponding to the range element signal R. Specifically, for each code corresponding to each transmit antenna TX, definition block 120 generates a decoded signal after decoding the range element signal R using that code. Definition block 120 stores the decoded signal of each code in memory 101.

[0070] For example, suppose the transmitting antenna TX1 is the target transmitting antenna. In this case, the definition block 120 in S30 is for the code C corresponding to any one of the other transmitting antennas TX2 to TX12. tx2 ~C tx12 Decode any codes that have not been decoded up to the last loop. For example, in a loop where a specific code C is specified... txn In the case of decoding, the decoded signal uses code C. txn *And represented by the following mathematical formula (2), where the code C txn * is used for operations performed by C txn The code is decoded using phase modulation. Here, code C txn * indicates that each element is coded as C. txn The complex conjugate vector, for example, is obtained by multiplying by C. txn This changes all elements to a code of 1.

[0071] [Mathematical Expression 2]

[0072]

[0073] In the subsequent S40, definition block 120 performs a Fast Fourier Transform (FFT) on the decoded signal. As a result, definition block 120 obtains the Doppler frequency spectrum of the mixed received signal. This frequency spectrum represents the velocity spectrum corresponding to the peak values ​​of the target's velocity; it is discrete velocity data containing signal strength information for each velocity unit. Through this second FFT process, as shown in Figure 5, definition block 120 can obtain two-dimensional mapping data of distance and velocity. This two-dimensional mapping data can also be called an RV mapping. Furthermore, in the Fast Fourier Transform process, definition block 120 multiplies the range unit signal R by a window function. In this process, the window function other than a rectangular function is, for example, a Hanning function, a Gaussian function, etc.

[0074] In the above mathematical formula (2), P is in the case of k=n. nThe coefficient becomes 1. Therefore, as shown in Figure 6, the velocity spectrum becomes the peak value P. n The sum of the spectrum of P and the spectrum diffused by other terms. n The spectrum resulting from terms other than these is equivalent to the sidelobe signal component. Furthermore, in the example shown in Figure 6, for simplicity, it is represented by codes from the two transmit antennas TX1 and TX2 respectively. tx1 C tx2 The range unit signal R of the received signal after the modulated transmitted signal is reflected at the target.

[0075] In the subsequent S50, suppression block 130 detects peaks from the frequency spectrum. In peak detection, suppression block 130 can, for example, determine the frequency element with the maximum intensity as the peak location. Suppression block 130 detects peaks, for example, by performing CFAR (Constant False Alarm Rate) processing. Suppression block 130 at least acquires the determined peak location and its peak intensity as peak information associated with the detected peak. Peak information may include the phase at the peak, etc. In the decoded signal RC... txn In the case of *, peak detection is equivalent to detecting P in mathematical formula (2). n The peak value in the frequency spectrum of the decoded signal is an example of the "object signal component" that corresponds to the received signal component that is the object in the decoded signal.

[0076] Then, in S60, the suppression block 130 selects an algorithm for sidelobe suppression processing. The suppression block 130 selects an algorithm from multiple algorithms pre-stored in the memory 101, etc., based on characteristic parameters related to the performance of each algorithm.

[0077] For example, characteristic parameters are parameters related to the computational complexity of each algorithm. Suppression block 130 obtains the computational complexity of each algorithm related to the characteristic parameters. Suppression block 130 selects the algorithm with the minimum computational complexity for use in sidelobe suppression processing. In particular, in this embodiment, suppression block 130 selects algorithms related to the estimation processing of sidelobe signal components in sidelobe suppression processing.

[0078] For example, the characteristic parameter is the target peak number N. pk Target peak frequency f pk Chirping number N c Code C txn CDM multiplexing number N cdm SN ratio χ tgt At least one of them. Characteristic parameters are specified for each algorithm. For example, characteristic parameters include content common to all algorithms.

[0079] Here, the target peak number N pkIt refers to the number of peaks in the decoded signal spectrum detected in S50, with the target peak frequency f. pk This represents the frequency of each peak value. The chirp count N c It is the number of chirps in each transmission cycle of the transmitted signal. CDM multiplexing number N cdm It is code C txn The multiplexing number of the transmitted signal after multiplexing, i.e., the code C used. txn The quantity.

[0080] SN to χ tgt This is the ratio of the peak intensity in the decoded signal to the noise floor (size) of the thermal noise, i.e., the ratio of the peak intensity relative to the noise floor of the thermal noise (see Figure 7). The thermal noise can be a parameter that can be theoretically estimated, related to the circuit structure and ambient temperature in the radar device 1. Alternatively, the thermal noise can be a parameter related to the received signal strength in areas where the target is not present in the RV mapping. Furthermore, the thermal noise related to the received signal strength can be thermal noise corresponding to the average, median, or mode of the received signal strength in the aforementioned areas.

[0081] The following explanation assumes that the algorithm selected by the suppression block 130 is capable of executing two algorithms, A1 and A2.

[0082] Algorithm A1 is an algorithm that estimates the sidelobe signal components by convolving the target peak with the Fourier-transformed code. As detailed in Figure 8, when Algorithm A1 is executed, the suppression block 130 estimates the code components C in the sidelobe signal components of the decoded signal spectrum. txn *C txk Perform a Fourier transform to generate code component C txn *C txk The spectrum. Suppression block 130 suppresses the code component C. txn *C txk The spectrum of the target peak is convolved with the peak spectrum to obtain the estimated spectrum of the sidelobe signal components. Furthermore, the peak spectrum is the spectrum after replacing the signal intensity outside the peak in the decoded signal spectrum with zero. Figure 8 shows the spectrum for code C. tx1 The code components C after the peak spectrum convolution Fourier transform of the decoded signal. tx2 *C tx1 An example of the spectrum. In this case, as shown in Figure 8, it is presumed that for code C... tx1 The sidelobe signal components in the spectrum of the decoded signal after decoding other codes.

[0083] Algorithm A2 is an algorithm that estimates the sidelobe signal components by performing a Fourier transform on the product of the inverse Fourier transform of the target peak and the code component. As detailed in Figure 9, when executing Algorithm A2, the suppression block 130 performs an inverse Fourier transform on the peak spectrum. Thus, the suppression block 130 obtains the time signal of the peak component. The suppression block 130 multiplies the time signal of the peak component by the code component C. txn *C txk Suppression block 130 is achieved by multiplying the code component C. txn *C txk The time signal is subjected to Fourier transform to obtain the estimated spectrum of the sidelobe signal components. Furthermore, Figure 9 shows the spectrum for code C. tx1 The peak spectrum time signal of the decoded signal after decoding is multiplied by the code component C. tx2 *C tx1 For example. Therefore, in Figure 9, it is presumed that for code C tx1 The sidelobe signal components in the spectrum of the decoded signal after decoding other codes.

[0084] Suppression block 130 selects the algorithm with the lower computational complexity f1 or f2 related to the characteristic parameter from the above algorithms A1 and A2. The computational complexity f1 and f2 of each algorithm A1 and A2 are defined, for example, as values ​​related to the number of data multiplications up to obtaining the estimated spectrum of the sidelobe signal components from the peak spectrum. The computational complexity f1 of algorithm A1 is related to the CDM multiplexing number N, which is a characteristic parameter. cdm Target peak number N pk and the number of chirps N c Related. Specifically, the relationship between the computational quantity f1 and the above three characteristic parameters is represented by the following formula (3).

[0085] [Mathematical Expression 3]

[0086]

[0087] On the other hand, the computational complexity f2 of algorithm A2 and the CDM reuse number N, which is a characteristic parameter, are related. cdm and the number of chirps N c Related. Specifically, the relationship between the computational quantity f2 and the two characteristic parameters mentioned above is represented by the following equation (4).

[0088] [Mathematical Expression 4]

[0089]

[0090] Based on the above relationships, the suppression block 130 determines which of the algorithms A1 and A2 has the lower computational complexity f1 and f2. The suppression block 130 then selects the algorithms A1 and A2 with the lower computational complexity f1 and f2 as the algorithms A1 and A2 that will be actually executed in subsequent steps.

[0091] In the subsequent S70, the suppression block 130 performs sidelobe suppression processing. Specifically, the suppression block 130 performs estimation processing of sidelobe signal components using selected algorithms A1 and A2. Then, the suppression block 130 performs removal processing to remove the estimated sidelobe signal components from the spectrum of the decoded signal. Through the sidelobe suppression processing that includes the above estimation and removal processing, the suppression block 130 obtains the spectrum (suppressed spectrum) of the decoded signal spectrum with the sidelobe signal components suppressed.

[0092] Suppression block 130 performs sidelobe suppression processing for each of the multiple decoded signals after decoding by each code. For example, as shown in Figure 6, let's assume that the sidelobe suppression processing is performed on each of the multiple decoded signals after decoding by each code C. tx1 C tx2 Sidelobe suppression processing is performed on the range cell signal R after the separately modulated transmitted signals are reflected at the target. In this case, the suppression block 130 is based on the decoded signal RC. tx1 The peak spectrum P1^ detected in the spectrum of * is used to estimate the decoded signal RC. tx2 The sidelobe signal component C in the spectrum of * tx2 *C tx1 P1^. Then, the suppression block 130 receives the decoded signal RC. tx2 Remove the sidelobe signal component C from the spectrum of * tx2 *C tx1 P1^. Similarly, the suppression block 130 is based on the decoded signal RC. tx2 The peak spectrum P2^ detected in the spectrum of * is used to estimate the decoded signal RC. tx1 The sidelobe signal component C in the spectrum of * tx1 *C tx2 P2^. Then, the suppression block 130 receives the decoded signal RC. tx1 Remove the sidelobe signal component C from the spectrum of * tx1 *C tx2 P2^.

[0093] Furthermore, Figure 6 illustrates sidelobe suppression processing when the transmitted signal is modulated using two types of codes for simplicity. However, even when three or more types of codes are used in the modulation, the suppression block 130 can perform the same sidelobe suppression processing. For example, this applies even when the transmitted signals from each of the 12 transmit antennas TX are modulated with different codes. In this case, the suppression block 130 estimates the sidelobe signal components in the other decoded signals from the respective peak values ​​of the 12 types of decoded signals after decoding each code, and then removes each sidelobe signal component from each decoded signal.

[0094] Furthermore, the suppression block 130 can also perform iterative repetitive sidelobe suppression processing. The iteration is based on extracting the peak spectrum from the decoded signal spectrum with suppressed sidelobe signal components, re-estimating the sidelobe signal components in the spectra of other decoded signals, and removing the re-estimated sidelobe signal components from those other decoded signal spectra. By performing an appropriate number of iterations, the suppression block 130 can suppress sidelobe signal components to a greater extent.

[0095] Subsequently, in S80, output block 140 acquires target information from the frequency spectrum. The target information includes at least one of the target's range, speed, and bearing. If the target information includes bearing, output block 140 estimates the bearing from the frequency spectrum, for example, using the DoA (Direction of Arrival) method. Output block 140 can output the target information to an onboard ECU outside the radar device 1. Alternatively, output block 140 can output the target information to a center outside the vehicle.

[0096] Referring to Figure 9, the difference in dynamic range PSR between the case with and without sidelobe suppression described above is explained. Assuming a target, the dynamic range PSR can be expressed as the ratio of the maximum value of the target's peak to the sidelobes. Without sidelobe removal, this dynamic range PSR is determined by the total number of chirps N of the transmitted signal. c The number N of transmitting antennas modulated by CDM code tx The relationship is satisfied by the following mathematical expression (5).

[0097] [Mathematical Expression 5]

[0098]

[0099] On the other hand, when the removal process shown in this embodiment is implemented, the dynamic range PSR satisfies the relationship expressed by the following mathematical formula (6).

[0100] [Mathematical Expression 6]

[0101]

[0102] That is, in radar device 1 that performs sidelobe suppression, the dynamic range PSR is larger compared to radar device 1 that does not perform it.

[0103] According to the first embodiment described above, the algorithm followed in the estimation processing of sidelobe signal components is selected based on the characteristic parameters upon which the performance of each algorithm depends. Since the characteristic parameters are parameters in the decoded signal or associated signal, the algorithm can be selected based on the reception conditions of the mixed received signal. Therefore, the algorithm followed in the suppression processing of sidelobe signal components can be determined according to the conditions.

[0104] (Second Implementation)

[0105] The second embodiment is a variation of the first embodiment.

[0106] In the second embodiment, the suppression block 130 estimates the sidelobe signal components from the matrix expression established between the decoded signal spectrum and the true peak spectrum. For example, for simplicity, assuming there are two transmitting antennas TX1 and TX2, the decoded signal RC... tx1 *and RC tx2 *Set them to P respectively 1dec and P 2dec Furthermore, the actual peak signal component caused by the transmitted signal from transmit antenna TX1 is designated as P1, and the actual peak signal component caused by the transmitted signal from transmit antenna TX2 is designated as P2. In this case, the decoded signal spectrum P 1dec P 2dec The relationship between the actual peak spectra P1 and P2 and the matrix expression is represented by the following mathematical formula (7).

[0107] [Number 7]

[0108]

[0109] Furthermore, C in the first item of the matrix on the right 12 Indicate C tx1 *C tx2 C 21 Indicate C tx2 *C tx1 Here, let P be the matrix representing the spectrum of the decoded signal on the left side of equation (7), let C+I be the matrix representing the first term on the right side (I is the identity matrix), and let P be the matrix representing the true peak spectrum of the second term on the right side. t At this point, mathematical expression (7) can be replaced by the following mathematical expression (8).

[0110] [Mathematical Expression 8]

[0111]

[0112] In the above mathematical formula (8), the sidelobe signal component is the CP of the first term on the right. t Therefore, since the matrix (C+I) is derived from the code and the target peak frequency f pk Given that, therefore, if we presume P t Then the sidelobe signal components can also be inferred. Here, mathematical formula (8) can be transformed into the following mathematical formula (9).

[0113] [Mathematical Expression 9]

[0114]

[0115] That is, the suppression block 130 can be solved by solving the above mathematical expression (9) to obtain P. t and P t Multiply by C to infer the sidelobe signal components.

[0116] In S60 of this embodiment, the suppression block 130 selects P from multiple algorithms. t The solution algorithm is as follows. For example, suppression block 130 selects a solution algorithm from three algorithms. One of the solution algorithms is the Jacobi method. Another solution algorithm is the Gauss-Seidel method. Furthermore, another solution algorithm is to multiply the inverse or pseudo-inverse of matrix (C+I) by P.

[0117] Suppression block 130 selects P t The convergent algorithm is used as the solution algorithm. In other words, suppression block 130 selects P. t The computational complexity of the algorithm will not become infinite. t Whether the convergence occurs is determined by the properties of the matrix (C+I). Since the matrix (C+I) is determined by the code and peak frequency as described above, in this embodiment, the code and peak frequency become characteristic parameters. Specifically, the suppression block 130 is based on the maximum eigenvalue λ of the matrix C. 1max and matrix (I+C) L ) -1 C U The largest eigenvalue λ 2max The algorithm is selected based on the absolute value of the matrix C. L It is a lower triangular matrix of matrix C, matrix C U It is the upper triangular matrix of matrix C.

[0118] (Other implementation methods)

[0119] The above describes several implementation methods, but this disclosure is not to be construed as being limited to these implementation methods. It can be applied to various implementation methods and combinations without departing from the spirit of this disclosure.

[0120] In a variant, the suppression block 130 may replace the decoded signal to remove sidelobe signal components from the range cell signal. In this case, the range cell signal is an example of an "associated signal" related to the decoded signal.

[0121] In a modified example, the transmit signal generation unit 2 may apply modulation using a different code to each antenna group comprising multiple transmit antennas TX. In this case, a different code is applied to the transmit signal for each of the multiple antenna groups comprising a predetermined number of transmit antennas TX. In this case, the control unit 100 performs a removal process for each code of each antenna group. Furthermore, the transmit signal corresponding to each transmit antenna TX within the antenna group is subjected to phase-shift modulation or amplitude modulation, making it possible to separate the received signal component corresponding to each transmit signal.

[0122] In a modified example, the output block 140 of S80 may output the frequency spectrum to an external device as target information. For example, the output block 140 may output the frequency spectrum to an on-board ECU external to the radar device 1. In this case, the on-board ECU at the output destination may obtain the target's position, etc., from the peak values ​​of the target contained in the frequency spectrum.

[0123] In a variant, the radar device 1 may have only a single transmitting antenna TX. In this case, the transmitting signal generation unit 2 generates a transmitting signal for a single transmitting antenna, which is a mixture of multiple transmitting signals modulated by different codes.

[0124] In a variant, the suppression block 130 may select an algorithm based solely on the unique characteristic parameters that are not common to each algorithm.

[0125] In variations, the dedicated computer constituting the control unit 100 may be an integrated ECU that integrates the vehicle's driving control. Alternatively, the dedicated computer constituting the control unit 100 may be a judgment ECU that determines the driving task in the vehicle's driving control. Or, the dedicated computer constituting the control unit 100 may be a monitoring ECU that monitors the vehicle's driving control. Or, the dedicated computer constituting the control unit 100 may be an evaluation ECU that evaluates the vehicle's driving control.

[0126] In variations, the dedicated computer constituting the control unit 100 may be a navigation ECU that navigates the vehicle's driving path. Alternatively, the dedicated computer constituting the control unit 100 may be a locator ECU that estimates the vehicle's own state quantities. Or, the dedicated computer constituting the control unit 100 may be an actuator ECU that controls the vehicle's driving actuators. Or, the dedicated computer constituting the control unit 100 may be an HCU (Hman Machine Interface) Control Unit that controls information prompts within the vehicle. Alternatively, the dedicated computer constituting the control unit 100 may be a computer outside the vehicle, such as an external center or mobile terminal capable of communicating with the vehicle.

[0127] In a variation, the dedicated computer constituting the control unit 100 may have at least one of digital circuitry and analog circuitry as a processor. Here, the digital circuitry may be, for example, at least one of ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), SOC (System on a Chip), PGA (Programmable Gate Array), and CPLD (Complex Programmable Logic Device). Furthermore, such digital circuitry may have a memory storing the program.

[0128] In a variation, the mobile body to which the control unit 100 is applied may be, for example, an autonomous robot capable of cargo handling or information collection via autonomous driving or remote operation. Furthermore, the autonomous robot may also be an autonomous driving robot including an autonomous vehicle.

[0129] In addition to the methods described above, the above-described embodiments and modifications can also be configured as control devices that can be mounted on a mobile body and have at least one processor 102 and one memory 101. Specifically, the above-described embodiments and modifications can also be implemented as processing circuits (e.g., processing ECUs) or semiconductor devices (e.g., semiconductor chips).

[0130] (The disclosure of technical ideas)

[0131] This specification discloses several technical ideas described in the following list of items. Several items are sometimes described in subsequent items in a multiple dependent form, selectively referencing an antecedent. Furthermore, several items are sometimes described in a multiple dependent form, referring to another multiple dependent form. These items described in multiple dependent forms define several technical ideas.

[0132] (Technical Idea 1)

[0133] A radar device, comprising:

[0134] More than one transmit antenna (TX);

[0135] Transmit signal generation unit (2) generates multiple types of transmit signals modulated by different codes transmitted from the transmit antenna;

[0136] A receiving antenna (RX) receives a mixed received signal, which is a combination of the transmitted signals after reflection from a reflector; and

[0137] Control unit (100), which processes the mixed received signal,

[0138] The control unit has:

[0139] Acquisition unit (110) acquires the mixed received signal received by the specific receiving antenna;

[0140] Definition unit (120) defines a plurality of decoding signals, which are obtained by decoding the mixed received signal by each code corresponding to each of the transmitted signals; and

[0141] A suppression unit (130) performs suppression processing according to any one of a plurality of algorithms, which suppresses sidelobe signal components detected in other decoded signals or associated signals related to the decoded signals in relation to a target signal component, the target signal component being a received signal component corresponding to the transmitted signal that is the target in a particular decoded signal.

[0142] The suppression unit selects the algorithm followed by the suppression process based on characteristic parameters related to the performance of each algorithm.

[0143] (Technical Idea 2)

[0144] According to the radar device of technical concept 1, the suppression unit performs estimation processing and removal processing in the suppression processing, the estimation processing estimating the sidelobe signal components, the removal processing subtracting the estimated sidelobe signal components from other decoded signals or the associated signals, and the suppression unit selects the algorithm for the estimation processing according to the characteristic parameters.

[0145] (Technical Idea 3)

[0146] According to the radar device of technical concept 1 or technical concept 2, the suppression unit selects the algorithm followed by the suppression process based on the characteristic parameters common to each of the selected candidates.

[0147] (Technical Idea 4)

[0148] According to any one of technical ideas 1 to 3, the radar device wherein the characteristic parameters include values ​​related to the computational complexity of each of the algorithms.

[0149] (Technical Idea 5)

[0150] According to the radar device described in technical concept 4, the characteristic parameter includes the number of peaks in the frequency spectrum of the decoded signal that are related to the reflector.

[0151] (Technical Idea 6)

[0152] According to the radar device described in technical concept 4 or technical concept 5, the characteristic parameter includes the frequency of the peak related to the reflector in the frequency spectrum of the decoded signal.

[0153] (Technical Idea 7)

[0154] According to any one of technical concepts 4 to 6, the radar device wherein the characteristic parameter includes the number of types of the code.

[0155] (Technical Idea 8)

[0156] According to any one of technical concepts 4 to 7, the radar device wherein the characteristic parameter comprises the ratio of the peak value of the frequency spectrum of the decoded signal related to the reflector to the thermal noise.

[0157] Furthermore, the technical ideas 1 to 8 mentioned above can also be implemented using radar control methods and radar control programs.

Claims

1. A radar device, characterized in that, include: More than one transmit antenna (TX); A transmitting signal generation unit (2) generates multiple types of transmitting signals modulated by different codes transmitted from the transmitting antenna; a receiving antenna (RX) receives a mixed receiving signal formed by the mixing of the transmitting signals after reflection by a reflector; and a control unit (100) processes the mixed receiving signal, the control unit having: an acquisition unit (110) that acquires the mixed receiving signal received by a specific receiving antenna; a definition unit (120) that defines multiple decoding signals obtained by decoding the mixed receiving signal with each code corresponding to each of the transmitting signals; and a suppression unit (130) that performs suppression processing according to any one of multiple algorithms, the suppression processing suppressing sidelobe signal components detected in other decoded signals in relation to a target signal component, the target signal component being a received signal component corresponding to the transmitting signal that is the target in the specific decoded signal, the suppression unit selecting the algorithm followed by the suppression processing according to characteristic parameters related to the performance of each algorithm.

2. The radar device according to claim 1, characterized in that, The suppression unit performs estimation processing and removal processing in the suppression process. The estimation processing estimates the sidelobe signal components, and the removal processing subtracts the estimated sidelobe signal components from other decoded signals or associated signals. The suppression unit selects the algorithm for the estimation processing based on the characteristic parameters.

3. The radar device according to claim 1, characterized in that, The suppression unit selects the algorithm followed by the suppression process based on the characteristic parameters common to the selected candidate algorithms.

4. The radar device according to claim 1, characterized in that, The characteristic parameters include values ​​related to the computational complexity of each algorithm.

5. The radar device according to claim 4, characterized in that, The characteristic parameter includes the number of peaks in the frequency spectrum of the decoded signal that are related to the reflector.

6. The radar device according to claim 4, characterized in that, The characteristic parameter includes the frequency of the peak value in the frequency spectrum of the decoded signal that is related to the reflector.

7. The radar device according to claim 4, characterized in that, The characteristic parameter includes the number of types of the code.

8. The radar device according to claim 4, characterized in that, The characteristic parameter includes the ratio of the peak value related to the reflector in the frequency spectrum of the decoded signal to the thermal noise.

9. A radar control method, executed by a processor (102), for controlling a radar device (1), the radar device comprising one or more transmitting antennas (TX), a transmitting signal generation unit (2), and a receiving antenna (RX), the transmitting signal generation unit generating multiple types of transmitting signals modulated by different codes transmitted from the transmitting antennas, the receiving antenna receiving a mixed receiving signal composed of the transmitted signals after reflection by a reflector, characterized in that, include: Acquire the mixed received signal received by the specific receiving antenna; A plurality of decoded signals are defined, which are obtained by decoding the mixed received signal with each of the codes corresponding to each of the transmitted signals; and a suppression process is performed according to any of a plurality of algorithms, which suppresses sidelobe signal components detected in other decoded signals in relation to a target signal component, which is a received signal component corresponding to the transmitted signal that is the target in a particular decoded signal, in other decoded signals or associated signals of the decoded signals, wherein performing the suppression process includes selecting the algorithm followed by the suppression process according to characteristic parameters related to the performance of each of the algorithms.

10. A radar control program, stored in a storage medium (101), comprising commands executed by a processor (102) to control a radar device (1), the radar device including one or more transmitting antennas (TX), a transmitting signal generation unit (2), and a receiving antenna (RX), the transmitting signal generation unit generating multiple types of transmitting signals modulated by different codes transmitted from the transmitting antennas, the receiving antenna receiving a mixed receiving signal formed by the mixing of the transmitted signals after reflection from a reflector, characterized in that, The command includes: acquiring the hybrid received signal received by a specific receiving antenna; defining a plurality of decoded signals obtained by decoding the hybrid received signal with each of the codes corresponding to each of the transmitted signals; and performing a suppression process according to any one of a plurality of algorithms, the suppression process suppressing sidelobe signal components detected in other decoded signals in relation to a target signal component, which is a received signal component corresponding to the transmitted signal as the target in the specific decoded signal, the suppression process including: selecting the algorithm followed by the suppression process according to characteristic parameters related to the performance of each of the algorithms.

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