Radar device, radar control method, and radar control program

Abstract

A control unit of this radar device includes an acquiring unit that acquires a mixed reception signal received by a specific reception antenna. The control unit includes a defining unit that defines a plurality of decoded signals obtained by decoding the mixed reception signal for each code corresponding to each transmitted signal. The control unit includes a suppression unit. The suppression unit executes suppression processing for suppressing, in another decoded signal or a related signal related to a specific decoded signal, side lobe signal components detected in the other decoded signal in correlation with a target signal component corresponding to a transmitted signal of interest in the specific decoded signal. The suppression unit executes the suppression processing in accordance with any one of a plurality of algorithms. The suppression unit selects the algorithm to be followed by the suppression processing in accordance with a characteristic parameter correlated to the performance of each algorithm.

Description

Radar device, radar control method, and radar control program CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2023-173008 filed in Japan on October 4, 2023, and the contents of the original application are incorporated by reference in their entirety.

[0002] The present disclosure relates to a technique for controlling a radar device.

[0003] Patent Literature 1 discloses a MIMO radar using a pseudorandom phase modulation method. This MIMO radar transmits transmission signals modulated with different CDM codes from each transmitting antenna. The MIMO radar generates decoded signal spectra by decoding the received signals according to each CDM code, and estimates side lobe signal components from each decoded signal spectrum. The MIMO radar obtains a decoded signal spectrum in which the side lobe signal components are suppressed by subtracting each estimated side lobe signal component from the decoded signal spectrum corresponding to the target transmitting antenna.

[0004] U.S. Patent No. 9,952,319

[0005] Incidentally, several algorithms have been proposed for use in suppressing side lobe signal components. The performance of each algorithm changes depending on the situation. However, Patent Document 1 does not describe how to determine the algorithm appropriate for the situation.

[0006] An object of the present disclosure is to provide a radar device capable of determining, depending on the situation, an algorithm to be followed in the suppression process of side lobe signal components.Another object of the present disclosure is to provide a radar control method capable of determining, depending on the situation, an algorithm to be followed in the suppression process of side lobe signal components.A still further object of the present disclosure is to provide a radar control program capable of determining, depending on the situation, an algorithm to be followed in the suppression process of side lobe signal components.

[0007] The technical means of the present disclosure for solving the problems will be described below. Note that the reference numerals in parentheses in the claims indicate the correspondence with the specific means described in the embodiments described later in detail, and do not limit the technical scope of the present disclosure.

[0008] A first aspect of the present disclosure is a radar device comprising: one or more transmitting antennas; a transmitting signal generating unit that generates multiple types of transmitting signals modulated with different codes and transmitted from the transmitting antennas; a receiving antenna that receives a mixed receiving signal formed by mixing the transmitting signals reflected by a reflecting object; and a control unit that processes the mixed receiving signal, wherein the control unit has: an acquiring unit that acquires the mixed receiving signal received at a specific receiving antenna; a defining unit that defines multiple decoded signals obtained by decoding the mixed receiving signal for each code corresponding to each transmitting signal; and a suppressing unit that executes suppression processing in accordance with one of multiple algorithms to suppress side lobe signal components detected in other decoded signals that correlate with target signal components, which are received signal components corresponding to a transmitting signal that is a target in the specific decoded signal, in the other decoded signals or related signals related to the decoded signals, wherein the suppressing unit selects an algorithm to be followed for the suppression processing in accordance with characteristic parameters that correlate with the performance of each algorithm.

[0009] A second aspect of the present disclosure is a radar control method executed by a processor to control a radar device including one or more transmitting antennas, a transmitting signal generating unit that generates multiple types of transmitting signals modulated with different codes and transmitted from the transmitting antennas, and a receiving antenna that receives a mixed receiving signal formed by mixing the transmitting signals reflected by a reflecting object, the method including: acquiring the mixed receiving signal received at a specific receiving antenna; defining multiple decoded signals obtained by decoding the mixed receiving signal for each code corresponding to each transmitting signal; and performing a suppression process in accordance with one of a plurality of algorithms to suppress side lobe signal components detected in other decoded signals that are correlated with target signal components, which are received signal components corresponding to the transmitting signal that is the target in the specific decoded signal, in the other decoded signals or related signals related to the decoded signals, wherein performing the suppression process includes selecting an algorithm to be followed by the suppression process in accordance with characteristic parameters correlated to the performance of each algorithm.

[0010] A third aspect of the present disclosure is a radar control program stored in a storage medium and executed by a processor to control a radar device including one or more transmitting antennas, a transmitting signal generating unit that generates multiple types of transmitting signals modulated with different codes and transmitted from the transmitting antennas, and a receiving antenna that receives a mixed receiving signal obtained by mixing the transmitting signals reflected by a reflecting object, wherein the instructions include: acquiring the mixed receiving signal received at a specific receiving antenna; defining multiple decoded signals obtained by decoding the mixed receiving signal for each code corresponding to each transmitting signal; and executing a suppression process in accordance with one of a plurality of algorithms to suppress side lobe signal components detected in other decoded signals that are correlated with target signal components, which are received signal components corresponding to the transmitting signal that is the target in the specific decoded signal, in the other decoded signals or related signals related to the decoded signals, wherein executing the suppression process includes selecting an algorithm to be followed by the suppression process in accordance with characteristic parameters correlated to the performance of each algorithm.

[0011] According to the first to third aspects, an algorithm to be used in the process of suppressing side lobe signal components is selected according to characteristic parameters on which the performance of each algorithm depends. Since the characteristic parameters are for the decoded signal or the related signal, the algorithm can be selected according to the reception conditions of the mixed received signal. Therefore, it may be possible to determine the algorithm to be used in the process of suppressing side lobe signal components according to the conditions.

[0012] FIG. 1 is a block diagram showing the overall configuration of a radar device according to a first embodiment. FIG. 2 is a block diagram showing the functional configuration of a control unit according to the first embodiment. FIG. 3 is a graph showing an example of a transmission signal according to the first embodiment. FIG. 4 is a flowchart showing a radar control method according to the first embodiment. FIG. 5 is a schematic diagram showing an overview of signal processing for generating a frequency spectrum of a decoded signal from a range bin signal. FIG. 6 is a schematic diagram showing an overview of side lobe suppression processing. FIG. 7 is a diagram showing an example of a frequency spectrum for explaining the definition of an S / N ratio. FIG. 8 is a schematic diagram for explaining an example of an algorithm. FIG. 9 is a schematic diagram for explaining another example of an algorithm. FIG. 10 is a schematic diagram showing the difference between a case where side lobe signal components are suppressed and a case where they are not suppressed.

[0013] Hereinafter, multiple embodiments of the present disclosure will be described with reference to the drawings. Note that corresponding components in each embodiment are designated by the same reference numerals, and redundant description may be omitted. Furthermore, when only a portion of the configuration is described in each embodiment, the configuration of another previously described embodiment may be applied to the remaining portions of the configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of multiple embodiments may be partially combined together even if not explicitly stated, provided that there is no particular problem with the combination.

[0014] 1 to 10 , a first embodiment of the present disclosure will be described. A radar device 1 is mounted 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, as target information, the distance to a target that is the object that reflected the transmission signal, the relative speed of the target, the direction of the target, and the like.

[0015] The target information output from the radar device 1 is input to an in-vehicle ECU (Electronic Control Unit) via an in-vehicle network such as a Control Area Network (CAN) (registered trademark) or Ethernet. The in-vehicle ECU executes various processes for automatic driving of the vehicle and advanced driving assistance based on the acquired target information of each target.

[0016] Processing based on target information includes, for example, collision avoidance processing, warning processing, etc. Collision avoidance processing is processing for controlling the vehicle to avoid collision with a target by controlling the brake system, steering system, etc. based on the target information of each target. Warning processing is processing for warning the driver of the possibility of collision with a target based on the target information of each target.

[0017] 1, the radar device 1 of this embodiment includes a transmission signal generating unit 2, a plurality of transmission circuits 3, a plurality of transmission antennas TX, a plurality of reception antennas RX, a plurality of reception circuits 4, and a control unit 100. The radar device 1 is a so-called MIMO (Multiple-Input-Multiple-Output) radar that transmits transmission signals from a plurality of transmission antennas TX to artificially increase the number of reception antennas RX beyond the actual number.

[0018] The transmission signal generating unit 2 receives a control signal from the control unit 100 and generates a modulated signal in response to the control signal. This generated signal is, for example, a so-called chirp signal whose frequency varies over time (see FIG. 3 ). The generated signal is distributed to each channel of the transmitting circuit 3 and the receiving circuit 4 and output. The transmission signal generating unit 2 outputs, as a transmission signal, a generated signal to which a pseudo-random phase modulation using a different code is applied for each transmission channel corresponding to each transmitting antenna TX. This modulation method is also called code division multiplexing (CDM). As shown in FIG. 3 , in this embodiment, the transmission signals transmitted from different transmitting antennas TX are assumed to have substantially the same chirp transmission time, center frequency, and frequency band. In FIG. 3 , the transmission signals transmitted from two different transmitting antennas TX are represented by different line types, i.e., solid lines and dashed lines.

[0019] That is, in this embodiment, a transmission signal to which phase modulation with mutually different codes has been applied is transmitted to the outside world from each of the multiple transmission antennas TX. Note that, in relation to the transmission signal, a signal generated by the transmission antennas TX and output to the receiving circuit 4 is hereinafter referred to as a local signal.

[0020] The transmitting circuit 3 and the receiving circuit 4 are each mainly composed of a semiconductor integrated circuit device such as an MMIC (Monolithic Microwave Integrated Circuit). The transmitting circuit 3 is connected to a transmitting antenna TX and outputs a transmitting signal to the transmitting antenna TX. The transmitting circuit 3 has the same number of amplifiers 30 as the number of connected transmitting antennas TX. The amplifiers 30 amplify the transmitting signals output from the transmitting signal generating unit 2 and output them to the corresponding transmitting antennas TX.

[0021] The transmitting antenna TX converts an electrical signal, as a transmission signal, supplied from the transmission signal generating unit 2 into a radio wave signal and transmits it to the outside world. In this embodiment, twelve transmitting antennas TX are provided. Hereinafter, when each transmitting antenna TX is to be individually distinguished, it will be referred to as a transmitting antenna TXn (n is a natural number from 1 to 12). The transmitting antenna TX includes at least one antenna element. For example, the transmitting antenna TX is a patch antenna including multiple flat antenna elements. The antenna elements are arranged on the surface opposite to the ground plane of a dielectric substrate having a ground plane on one surface, so as to face the ground plane. The multiple antenna elements are connected, for example, in series, by a feeder line that supplies an electrical signal.

[0022] The receiving antenna RX receives, as a received signal, a radio wave signal including a transmitted signal reflected by a target as a reflector in the external world. Each of the multiple receiving antennas RX receives a signal in a state in which the received signals corresponding to the transmitted signals from the multiple transmitting antennas TX are mixed together. Hereinafter, this mixed signal received by each receiving antenna RX will be referred to as a mixed received signal. Furthermore, the components of the received signals corresponding to the transmitted signals from the multiple transmitting antennas TX that are mixed together in the mixed received signal will be referred to as received signal components.

[0023] The receiving antenna RX converts the received signal as a radio wave signal into an electrical signal and outputs it to the corresponding receiving circuit 4. The receiving antenna RX is, for example, a patch antenna in the same manner as the transmitting antenna TX, in which at least one antenna element is connected in series by a feeder line.

[0024] The receiving circuit 4 is connected to the receiving antennas RX and acquires the signals received by the receiving antennas RX for each receiving channel corresponding to each receiving antenna RX. The receiving circuit 4 includes the same number of amplifiers 40 and signal mixers 41 as the number of connected receiving antennas RX.

[0025] The amplifier 40 amplifies the received signal received by the receiving antenna and outputs it to the signal mixer 41. The signal mixer 41 generates a beat signal by mixing the local signal from the transmission signal generating unit 2 with the received signal. The generated beat signal becomes an interference signal that represents the frequency difference between the received signal and the local signal. The beat signal is output to the control unit 100 after high-frequency components that deviate from the frequency difference between the received signal and the local signal have been filtered out by a low-pass filter (not shown).

[0026] The control unit 100 is connected to the transmission signal generating unit 2 and the receiving circuit 4 via at least one of, for example, a LAN (Local Area Network) line, a wire harness, an internal bus, and a wireless communication line. The control unit 100 is configured to include at least one dedicated computer.

[0027] The dedicated computer constituting the control unit 100 may be a radar ECU (Electronic Control Unit) specialized for controlling the radar device 1. The dedicated computer constituting the control unit 100 may be a radar supervising ECU that comprehensively controls a plurality of radar devices 1 mounted on a moving object. The dedicated computer constituting the control unit 100 may be a sensor supervising ECU that comprehensively controls a plurality of sensors including the radar device 1 and other sensors such as LiDAR (Light Detection and Ranging / Laser Imaging Detection and Ranging).

[0028] The dedicated computer constituting the control unit 100 has at least one memory 101 and one processor 102. The memory 101 is at least one type of non-transitory tangible storage medium, such as a semiconductor memory, a magnetic medium, or an optical medium, that non-temporarily stores computer-readable programs and data. Here, "storage" may refer to accumulation in which data is retained even when the vehicle is turned off, or temporary storage in which data is erased when the vehicle is turned off. The processor 102 includes at least one type of core, such as a central processing unit (CPU), a graphics processing unit (GPU), a reduced instruction set computer (RISC)-CPU, a data flow processor (DFP), or a graph streaming processor (GSP).

[0029] In the control unit 100, the processor 102 executes a plurality of instructions included in a radar control program stored in a memory 101 serving as a storage medium in order to control the radar device 1. In this way, the control unit 100 constructs a plurality of functional blocks for controlling the radar device 1. As shown in Fig. 2, the plurality of 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. Note that the above-mentioned functional blocks can also be referred to as an acquisition unit, a definition unit, a suppression unit, and an output unit, respectively, as functional units.

[0030] The radar control method in which the control unit 100 controls the radar device 1 through the cooperation of these blocks 110, 120, 130, and 140 is executed according to the radar control flow shown in Figure 4. This radar control flow is executed repeatedly while the radar device 1 is running. This radar control flow is executed, for example, for each reception channel, and one cycle is defined as the time it takes for all reception channels to be executed once. Note that each "S" in this radar control flow represents multiple steps executed by multiple commands included in the radar control program.

[0031] First, in S10, the acquisition block 110 acquires a mixed received signal. The mixed received signal is a beat signal obtained by mixing a local signal from the signal generating unit and a received signal from the receiving antenna RX. The beat 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 sampled at a predetermined time interval by an A / D converter.

[0032] In the next step S20, the definition block 120 performs a Fast Fourier Transform (FFT) process on the mixed received signal. As a result, the definition block 120 acquires the distance spectrum of each chirp in the mixed received signal. The acquired distance spectrum is a frequency spectrum showing peaks corresponding to the distance to the target, and is discrete distance data containing signal strength information for each bin (distance bin) corresponding to the distance as distance information. Thereafter, as shown in FIG. 5, N ｃ The Ns samples of each chirp are converted into distance data by FFT processing, and N ｃ The data from which the samples are extracted is expressed as a range bin signal R. Here, the symbol C originating from the transmission signal from the transmitting antenna TXn is ｔｘｎ The received signal component encoded by P ｎ The range bin signal R before decoding is the received signal component C before decoding from each transmitting antenna TX. ｔｘｎ P ｎ can be defined as the sum of the following equation (1):

[0033] In S30, definition block 120 defines a decoded signal corresponding to range bin signal R. Specifically, definition block 120 generates a decoded signal by decoding range bin signal R with each code corresponding to each transmitting antenna TX. Definition block 120 stores the decoded signal for each code in memory 101.

[0034] For example, suppose that the target transmitting antenna is the transmitting antenna TX1. In this case, the definition block 120 in S30 defines a code C corresponding to one of the other transmitting antennas TX2 to TX12. ｔｘ２ ~C ｔｘ１２ For example, a specific code C ｔｘｎ When decoding is performed for C ｔｘｎ Code C for decoding the phase modulation by ｔｘｎ ＊ Here, the symbol C is used to express the following formula (2). ｔｘｎ ＊ Each element is coded C ｔｘｎ is a vector that is the complex conjugate of, for example, C ｔｘｎ It is a code whose elements all become 1 when multiplied by .

[0035] In the next step S40, the definition block 120 performs a fast Fourier transform (FFT) on the decoded signal. As a result, the definition block 120 acquires the Doppler frequency spectrum of the mixed received signal. This frequency spectrum is a velocity spectrum showing peaks corresponding to the target's velocity, and is discrete velocity data containing signal strength information for each bin (velocity bin) corresponding to the velocity. Through this second FFT, the definition block 120 acquires two-dimensional map data of range and velocity, as shown in FIG. 5 . This two-dimensional map data may also be referred to as an RV map. In the fast Fourier transform, the definition block 120 multiplies the range bin signal R by a window function. In this process, the window function other than a rectangular function may be, for example, a Hanning function or a Gaussian function.

[0036] In the above formula (2), when k=n, P ｎ The coefficient of is 1. Therefore, as shown in FIG. 6, the velocity spectrum has a peak P ｎ The spectrum of this P is the sum of the spectrum of the P and the spectrum spread by other terms. ｎ In the example shown in FIG. 6, for simplicity, the spectrum of the terms other than ｔｘ１ , C ｔｘ２ 10 shows a range bin signal R based on a received signal reflected by a target from a transmitted signal modulated by each of the modulated signals.

[0037] In the next step S50, the suppression block 130 detects a peak from the frequency spectrum. In peak detection, the suppression block 130 may identify, for example, a frequency bin where the intensity is at a maximum value as the peak position. The suppression block 130 detects the peak by, for example, performing CFAR (Constant False Alarm Rate) processing. The suppression block 130 acquires at least the identified peak position and its peak intensity as peak information related to the detected peak. The peak information may include the phase of the peak, etc. The decoded signal RC ｔｘｎ ＊ In this case, peak detection is performed by P ｎ The peak in the frequency spectrum of the decoded signal is an example of a "target signal component" which is a received signal component that corresponds to the target transmitted signal in the decoded signal.

[0038] Then, in S60, the suppression block 130 selects an algorithm for the side lobe suppression process. The suppression block 130 selects from a plurality of algorithms stored in advance in the memory 101 or the like, in accordance with characteristic parameters correlated with the performance of each algorithm.

[0039] For example, the characteristic parameters are parameters that correlate with the amount of calculation for each algorithm. The suppression block 130 acquires the amount of calculation for each algorithm that correlates with the characteristic parameters. The suppression block 130 selects the algorithm with the smallest amount of calculation as the algorithm to be used for side lobe suppression processing. In particular, in this embodiment, the suppression block 130 selects an algorithm related to the estimation processing of side lobe signal components in the side lobe suppression processing.

[0040] For example, the characteristic parameters are the number of target peaks N ｐｋ , target peak frequency f ｐｋ , chirp number N ｃ , code C ｔｘｎ , CDM multiplex number N ｃｄｍ , S / N ratio χ ｔｇｔ The characteristic parameters are defined for each algorithm. For example, the characteristic parameters include those that are common to each algorithm.

[0041] Here, the number of target peaks N ｐｋ is the number of peaks in the decoded signal spectrum detected in S50, and the target peak frequency f ｐｋ is the frequency of each peak. ｃ is the number of chirps per transmission period in the transmission signal. ｃｄｍ is the symbol C ｔｘｎ The number of multiplexed transmission signals, i.e., the code C used ｔｘｎ is the number of

[0042] S / N ratio χ ｔｇｔis the ratio of the peak intensity in the decoded signal to the noise floor (magnitude) of the thermal noise, i.e., the ratio of the peak intensity to the noise floor of the thermal noise (see FIG. 7 ). The thermal noise may be thermal noise as a theoretically estimable parameter correlated with the circuit configuration and ambient temperature of the radar device 1. Alternatively, the thermal noise may be thermal noise as a parameter correlated with the received signal strength in a target-free area of ​​the RV map. Note that the thermal noise as a parameter correlated with the received signal strength may be thermal noise corresponding to the average, median, or mode of the received signal strength in the above-mentioned area.

[0043] The algorithm selected by the suppression block 130 will be described below assuming that two algorithms A1 and A2 are executable.

[0044] The algorithm A1 is an algorithm for estimating a side lobe signal component by convolving a target peak with a Fourier transformed code. Specifically, when the algorithm A1 is executed according to FIG. 8, the suppression block 130 estimates the code component C ｔｘｎ ＊ C ｔｘｋ is Fourier transformed to obtain the code component C ｔｘｎ ＊ C ｔｘｋ The suppression block 130 generates a spectrum of the code component C ｔｘｎ ＊ C ｔｘｋ The estimated spectrum of the side lobe signal component is obtained by convolving the spectrum of the target peak with the peak spectrum of the target peak. The peak spectrum is a spectrum obtained by replacing the signal intensity of the decoded signal spectrum with zero except for the peak. In FIG. 8, the symbol C ｔｘ１ For the peak spectrum of the decoded signal decoded for ｔｘ２ ＊ C ｔｘ１ In this case, in FIG. 8, the spectrum of the code C ｔｘ１The side lobe signal components in the decoded signal spectrum obtained by decoding the codes other than are estimated.

[0045] Algorithm A2 is an algorithm for estimating a side lobe signal component by Fourier transforming the result of multiplying the inverse Fourier transform of the target peak by the code component. Explained in detail with reference to FIG. 9, when this algorithm A2 is executed, the suppression block 130 performs an inverse Fourier transform process on the peak spectrum. As a result, 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 The suppression block 130 multiplies the code component C ｔｘｎ ＊ C ｔｘｋ The estimated spectrum of the side lobe signal component is obtained by Fourier transforming the time signal multiplied by the symbol C. ｔｘ１ For the time signal of the peak spectrum in the decoded signal decoded for ｔｘ２ ＊ C ｔｘ１ For this reason, in FIG. 9, the code C ｔｘ１ The side lobe signal components in the decoded signal spectrum obtained by decoding the codes other than are estimated.

[0046] The suppression block 130 selects the calculation amount f that correlates with the characteristic parameters from among the above algorithms A1 and A2. １ , f ２ The smaller of the computational load f １ , f ２ is defined as a value that correlates with the number of data multiplications from the peak spectrum to the estimated spectrum of the side lobe signal component. １ is the number of CDM multiplexes N as a characteristic parameter ｃｄｍ , the number of target peaks N ｐｋ , and the chirp number N ｃ Specifically, the amount of calculation f １The relationship expressed by the following equation (3) holds between and the above three characteristic parameters.

[0047] On the other hand, the computational complexity f ２ is the number of CDM multiplexes N as a characteristic parameter ｃｄｍ , and the chirp number N ｃ Specifically, the amount of calculation f ２ The relationship expressed by the following equation (4) holds between and the above two characteristic parameters.

[0048] The suppression block 130 reduces the amount of calculation f １ , f ２ The suppression block 130 determines whether the algorithm A1 or A2 has the least amount of calculation f １ , f ２ The algorithms A1 and A2 with the smallest number of errors are determined as the algorithms A1 and A2 to be actually executed in a later step.

[0049] In the next step S70, the suppression block 130 performs side lobe suppression processing. Specifically, the suppression block 130 performs side lobe signal component estimation processing using the selected algorithms A1 and A2. The suppression block 130 then performs removal processing to remove the estimated side lobe signal component from the decoded signal spectrum. Through the side lobe suppression processing including the above estimation processing and removal processing, the suppression block 130 acquires a spectrum in which the side lobe signal component has been suppressed from the decoded signal spectrum (suppressed spectrum).

[0050] The suppression block 130 performs side lobe suppression processing for each of the multiple decoded signals decoded by each code. For example, as shown in FIG. ｔｘ１ , C ｔｘ２ In this case, the suppression block 130 performs side lobe suppression processing on the range bin signal R that is a result of the transmission signal modulated by ｔｘ１ ＊ The peak spectrum P detected from the spectrum １ Based on , the decoded signal RCｔｘ２ ＊ The side lobe signal component C in the spectrum of ｔｘ２ ＊ C ｔｘ１ P １ Then, the suppression block 130 estimates this side lobe signal component C ｔｘ２ ＊ C ｔｘ１ P １ ^ is the decoded signal RC ｔｘ２ ＊ Similarly, the suppression block 130 removes the signal RC from the spectrum of the decoded signal RC. ｔｘ２ ＊ The peak spectrum P detected from the spectrum ２ Based on , the decoded signal RC ｔｘ１ ＊ The side lobe signal component C in the spectrum of ｔｘ１ ＊ C ｔｘ２ P ２ Then, the suppression block 130 estimates this side lobe signal component C ｔｘ１ ＊ C ｔｘ２ P ２ ^ is the decoded signal RC ｔｘ１ ＊ is removed from the spectrum.

[0051] For simplicity, Fig. 6 shows the side lobe suppression process when the transmission signal is modulated with two types of codes. However, the suppression block 130 can perform the side lobe suppression process in a similar manner even when three or more types of codes are used for modulation. For example, the same applies when the transmission signals from the 12 transmitting antennas TX are modulated with different codes. In this case, the suppression block 130 estimates the side lobe signal components in the other decoded signals from the peaks of the 12 types of decoded signals decoded for each code, and removes each side lobe signal component from each decoded signal.

[0052] The suppression block 130 may perform iterations of the side lobe suppression process. The iterations are processes of re-estimating the side lobe signal components in other decoded signal spectra based on a peak spectrum extracted from a decoded signal spectrum in which the side lobe signal components have been suppressed, and removing the re-estimated side lobe signal components from the other decoded signal spectra. By performing the iterations an appropriate number of times, the suppression block 130 can further suppress the side lobe signal components.

[0053] Then, in S80, the output block 140 acquires target information from the frequency spectrum. The target information includes at least one of the distance, speed, and direction of the target. If the target information includes the direction, the output block 140 estimates the direction from the frequency spectrum using, for example, a DoA (Direction of Arrival) method. The output block 140 may output the target information to an on-board ECU outside the radar device 1. Alternatively, the output block 140 may output the target information to a center outside the vehicle.

[0054] The difference in dynamic range PSR between when the above side lobe suppression is performed and when it is not performed will be explained with reference to Fig. 9. When one target is assumed, the dynamic range PSR can be expressed as the ratio from the maximum value of the peak of the target to the side lobe. When the suppression process is not performed, this dynamic range PSR is expressed as ｃ , the number of transmitting antennas modulated by CDM code N ｔｘ As a result, the relationship shown in the following formula (5) is satisfied.

[0055] On the other hand, when the removal process according to this embodiment is performed, the dynamic range PSR satisfies the relationship shown in the following equation (6).

[0056] That is, the radar device 1 that performs side lobe suppression has a larger dynamic range PSR than the radar device 1 that does not perform side lobe suppression.

[0057] According to the first embodiment described above, an algorithm to be used in the process of estimating side lobe signal components is selected according to characteristic parameters on which the performance of each algorithm depends. Since the characteristic parameters are for the decoded signal or the related signal, the algorithm can be selected according to the reception conditions of the mixed received signal. Therefore, it is possible to determine the algorithm to be used in the process of suppressing side lobe signal components according to the conditions.

[0058] Second Embodiment The second embodiment is a modification of the first embodiment.

[0059] In the second embodiment, the suppression block 130 estimates the side lobe signal component from a determinant that holds between the decoded signal spectrum and the true peak spectrum. For example, for simplicity, it is assumed that there are two transmitting antennas TX1 and TX2, and the decoded signal RC ｔｘ１ ＊ and R.C. ｔｘ２ ＊ P １ｄｅｃ and P ２ｄｅｃ Furthermore, let P be the true peak signal component resulting from the transmission signal from the transmitting antenna TX1. １ , the true peak signal component due to the transmission signal from the transmitting antenna TX2 is P ２ In this case, the decoded signal spectrum P １ｄｅｃ , P ２ｄｅｃ and the true peak spectrum P １ , P ２ is expressed by the determinant relationship shown in the following equation (7).

[0060] In addition, C in the matrix of the first term on the right side １２ is C ｔｘ１ ＊ C ｔｘ２ , C ２１ is C ｔｘ２ ＊ C ｔｘ１ Here, the matrix representing the left side of Equation (7), i.e., the decoded signal spectrum, is P, the matrix representing the first term on the right side is C+I (I is a unit matrix), and the matrix representing the true peak spectrum of the second term on the right side is P. ｔIn this case, the formula (7) can be replaced with the following formula (8).

[0061] In the above equation (8), the side lobe signal component is the first term on the right side, CP ｔ Therefore, the matrix (C+I) is the code and the target peak frequency f ｐｋ Since it is known from ｔ Here, Equation (8) can be transformed into Equation (9) below.

[0062] That is, the suppression block 130 converts the above equation (9) into P ｔ Solving for P ｔ By multiplying by C, the side lobe signal component can be estimated.

[0063] In S60 of this embodiment, the suppression block 130 is P ｔ The suppression block 130 selects a solution algorithm from among a plurality of algorithms. For example, the suppression block 130 selects a solution algorithm from among three algorithms. One solution algorithm is the Jacobi method. Another solution algorithm is the Gauss-Seidel method. Yet another solution algorithm is to multiply P by the inverse or pseudo-inverse of the matrix (C+I).

[0064] The suppression block 130 is P ｔ In other words, the suppression block 130 selects an algorithm that satisfies P ｔ Select an algorithm that does not make the amount of calculations for P infinite. ｔ The convergence of is determined by the properties of the matrix (C+I). As the matrix (C+I) is determined according to the sign and peak frequency as described above, in this embodiment, the sign and peak frequency are characteristic parameters. Specifically, the suppression block 130 detects the largest eigenvalue λ of the matrix C. １ｍａｘ , and the matrix (I+C Ｌ ) －１ C Ｕ The largest eigenvalue λ of ２ｍａｘ The algorithm is selected depending on the absolute value of the matrix CＬ is the lower triangular matrix of matrix C, Ｕ is the upper triangular matrix of the matrix C.

[0065] (Other Embodiments) Although multiple embodiments have been described above, the present disclosure should not be construed as being limited to those embodiments, and can be applied to various embodiments and combinations within the scope that does not deviate from the gist of the present disclosure.

[0066] In a variant, the suppression block 130 may remove the sidelobe signal components from the range bin signals instead of the decoded signal, in which case the range bin signals are an example of "related signals" related to the decoded signal.

[0067] In a modified example, the transmission signal generating unit 2 may modulate the transmission signal with a different code for each antenna set including multiple transmission antennas TX. In this case, a different code is assigned to the transmission signal for each of multiple antenna sets including a predetermined number of transmission antennas TX. In this case, the control unit 100 performs removal processing for each code of each antenna set. Note that the transmission signal corresponding to each transmission antenna TX in the antenna set is modulated with phase shift keying or amplitude modulation, making it possible to separate the corresponding reception signal component for each transmission signal.

[0068] In a modified example, the output block 140 of S80 may output the frequency spectrum as target information to an external device. For example, the output block 140 outputs the frequency spectrum to an in-vehicle ECU external to the radar device 1. In this case, the in-vehicle ECU to which the frequency spectrum is output acquires the target position and the like from the peak of the target included in the frequency spectrum.

[0069] In a modified example, the radar device 1 may include only a single transmitting antenna TX. In this case, the transmitting signal generating unit 2 generates a transmitting signal for the single transmitting antenna, which is a mixture of multiple transmitting signals modulated with different codes.

[0070] In a variant, the suppression block 130 may select an algorithm depending only on characteristic parameters that are not common to each algorithm.

[0071] In a modified example, the dedicated computer constituting the control unit 100 may be an integration ECU that integrates the driving control of the vehicle. The dedicated computer constituting the control unit 100 may be a determination ECU that determines a driving task in the driving control of the vehicle. The dedicated computer constituting the control unit 100 may be a monitoring ECU that monitors the driving control of the vehicle. The dedicated computer constituting the control unit 100 may be an evaluation ECU that evaluates the driving control of the vehicle.

[0072] In a modified example, the dedicated computer constituting the control unit 100 may be a navigation ECU that navigates the vehicle's driving route. The dedicated computer constituting the control unit 100 may be a locator ECU that estimates the vehicle's own state quantity. The dedicated computer constituting the control unit 100 may be an actuator ECU that controls the vehicle's driving actuators. The dedicated computer constituting the control unit 100 may be an HCU (Human Machine Interface (HMI) Control Unit) that controls information presentation in the vehicle. The dedicated computer constituting the control unit 100 may be a computer other than that of the vehicle, for example, an external center or mobile terminal that can communicate with the vehicle.

[0073] In a modified example, the dedicated computer constituting the control unit 100 may have at least one of a digital circuit and an analog circuit as a processor. Here, the digital circuit is at least one of an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a system on a chip (SOC), a programmable gate array (PGA), and a complex programmable logic device (CPLD). Such a digital circuit may also have a memory that stores a program.

[0074] In a modified example, the moving body to which the control unit 100 is applied may be, for example, an autonomous robot that can transport luggage or collect information by autonomous driving or remote driving. Furthermore, the autonomous robot may be an autonomous driving robot including an autonomous vehicle.

[0075] In addition to the embodiments described above, the above-described embodiments and modifications may be implemented as a control device that is configured to be mountable on a moving body and has at least one processor 102 and one memory 101. Specifically, the above-described embodiments and modifications may be implemented in the form of a processing circuit (e.g., a processing ECU) or a semiconductor device (e.g., a semiconductor chip).

[0076] (Disclosure of Technical Ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be described in a multiple dependent form, with the subsequent clause alternatively referring to the preceding clause. Furthermore, some clauses may be described in a multiple dependent form, with the subsequent clause referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0077] (Technical Idea 1) A system includes one or more transmitting antennas (TX), a transmitting signal generating unit (2) that generates a plurality of types of transmitting signals modulated by different codes and transmitted from the transmitting antenna, a receiving antenna (RX) that receives a mixed receiving signal obtained by mixing the transmitting signals reflected by a reflecting object, and a control unit (100) that processes the mixed receiving signal, wherein the control unit includes an acquiring unit (110) that acquires the mixed receiving signal received by a specific receiving antenna, a defining unit (120) that defines a plurality of decoded signals obtained by decoding the mixed receiving signal for each of the codes corresponding to each of the transmitting signals, and a suppressing unit (130) that executes suppression processing in accordance with one of a plurality of algorithms to suppress side lobe signal components detected in other decoded signals in correlation with target signal components that are received signal components corresponding to the transmitting signal that is the target in the specific decoded signal, in the other decoded signals or related signals related to the decoded signals, and wherein the suppressing unit A radar device that selects the algorithm to be followed by the suppression process according to a characteristic parameter that correlates with the performance of each of the algorithms.

[0078] (Technical Idea 2) The radar device according to Technical Idea 1, wherein the suppression unit executes an estimation process for estimating the side lobe signal component and a removal process for subtracting the estimated side lobe signal component from another decoded signal or the related signal in the suppression process, and selects the algorithm for the estimation process according to the characteristic parameters.

[0079] (Technical Idea 3) The radar device according to Technical Idea 1 or 2, wherein the suppression unit selects the algorithm to be subjected to the suppression process in accordance with the characteristic parameter common to each of the algorithms to be selected.

[0080] (Technical Concept 4) The radar device according to any one of Technical Concepts 1 to 3, wherein the characteristic parameters include values ​​that correlate with the amount of calculation of each of the algorithms.

[0081] (Technical Concept 5) The radar device according to Technical Concept 4, wherein the characteristic parameters include the number of peaks relating to the reflecting object in the frequency spectrum of the decoded signal.

[0082] (Technical Concept 6) The radar device according to Technical Concept 4 or 5, wherein the characteristic parameter includes a frequency of a peak related to the reflecting object in a frequency spectrum of the decoded signal.

[0083] (Technical Concept 7) The radar device according to any one of Technical Concepts 4 to 6, wherein the characteristic parameters include the number of types of the codes.

[0084] (Technical Idea 8) The radar device according to any one of Technical Ideas 4 to 7, wherein the characteristic parameter includes a ratio of a peak related to the reflecting object to thermal noise in a frequency spectrum of the decoded signal.

[0085] It should be noted that the above technical concepts 1 to 8 may be realized in the form of a radar control method and a radar control program.

Claims

1. A radar device comprising: one or more transmitting antennas (TX); a transmitting signal generating unit (2) that generates a plurality of types of transmitting signals modulated by different codes and transmitted from the transmitting antenna; a receiving antenna (RX) that receives a mixed receiving signal in which the transmitting signals reflected by a reflecting object are mixed; and a control unit (100) that processes the mixed receiving signal, wherein the control unit has: an acquiring unit (110) that acquires the mixed receiving signal received at a specific receiving antenna; a defining unit (120) that defines a plurality of decoded signals obtained by decoding the mixed receiving signal for each of the codes corresponding to each of the transmitting signals; and a suppressing unit (130) that executes a suppression process in accordance with one of a plurality of algorithms to suppress a side lobe signal component detected in another decoded signal in correlation with a target signal component that is a receiving signal component corresponding to the transmitting signal that is the target in the specific decoded signal, in the other decoded signal or a related signal related to the decoded signal, wherein the suppressing unit selects the algorithm to be followed by the suppression process in accordance with a characteristic parameter that correlates with the performance of each of the algorithms.

2. The radar device according to claim 1, wherein the suppression unit executes an estimation process for estimating the side lobe signal component and a removal process for subtracting the estimated side lobe signal component from other decoded signals or related signals in the suppression process, and selects the algorithm for the estimation process in accordance with the characteristic parameters.

3. The radar device according to claim 1, wherein the suppression section selects the algorithm to be followed in the suppression process in accordance with the characteristic parameters common to each of the algorithms to be selected.

4. The radar device according to claim 1, wherein the characteristic parameters include values ​​correlating with the amount of calculation of each of the algorithms.

5. The radar device according to claim 4, wherein said characteristic parameters include the number of peaks relating to said reflectors in the frequency spectrum of said decoded signal.

6. A radar device according to claim 4, wherein said characteristic parameters include a frequency of a peak relating to said reflector in a frequency spectrum of said decoded signal.

7. The radar device according to claim 4, wherein the characteristic parameters include the number of types of the codes.

8. The radar device according to claim 4, wherein said characteristic parameter includes a ratio of a peak relating to said reflector to thermal noise in the frequency spectrum of said decoded signal.

9. A radar control method executed by a processor (102) to control a radar device (1) having one or more transmitting antennas (TX), a transmitting signal generating unit (2) that generates multiple types of transmitting signals modulated with different codes and transmitted from the transmitting antennas, and a receiving antenna (RX) that receives a mixed receiving signal in which the transmitting signals reflected by a reflecting object are mixed, comprising: acquiring the mixed receiving signal received by a specific receiving antenna; defining multiple decoded signals in which the mixed receiving signal is decoded for each of the codes corresponding to each of the transmitting signals; and executing a suppression process in accordance with one of a plurality of algorithms to suppress side lobe signal components detected in other decoded signals in correlation with target signal components, which are receiving signal components corresponding to the transmitting signal targeted in the specific decoded signal, in the other decoded signals or related signals related to the decoded signals, wherein executing the suppression process includes selecting the algorithm to be followed by the suppression process in accordance with a characteristic parameter correlated to the performance of each of the algorithms.

10. A radar control program stored in a storage medium (101) for controlling a radar device (1) having one or more transmitting antennas (TX), a transmitting signal generating unit (2) that generates a plurality of types of transmitting signals modulated by different codes and transmitted from the transmitting antennas, and a receiving antenna (RX) that receives a mixed receiving signal in which the transmitting signals reflected by a reflecting object are mixed, the program including instructions to be executed by a processor (102), the instructions including: acquiring the mixed receiving signal received by a specific receiving antenna; defining a plurality of decoded signals in which the mixed receiving signal is decoded for each of the codes corresponding to each of the transmitting signals; and executing a suppression process in accordance with any of a plurality of algorithms, the suppression process suppressing a side lobe signal component detected in another decoded signal in correlation with a target signal component, which is a receiving signal component corresponding to the transmitting signal targeted in the specific decoded signal, in the other decoded signal or a related signal related to the decoded signal, and the execution of the suppression process is a radar control program for selecting the algorithm to be followed by the suppression process in response to a characteristic parameter correlated with the performance of each of the algorithms.

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