WO2025216145A1 - Radar system, radar control device, radar control method, and radar control program - Google Patents

Abstract

A processor of this radar system is configured to transmit, in addition to the shift amount and from each transmission antenna, a transmission signal having an initial phase that has been changed in accordance with the transmission antenna. The processor is configured to set a candidate of the correspondence relationship between a plurality of peaks and the plurality of transmission antennas in a speed spectrum defined by reception signals obtained via the reception of transmission signals from the plurality of transmission antennas by a reception antenna. When the phase difference between the peaks correlated with the spatial disposition of the transmission antennas is confirmed by the combination of the peak corresponding to the candidate and the initial phase, the processor is configured to output sensing data correlated with the reception signals in which the correspondence relationship by the candidate is defined.

Description

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

This application is based on Patent Application No. 2024-62386 filed in Japan on April 8, 2024, and the contents of the original application are incorporated by reference in their entirety.

This disclosure relates to radar control technology for controlling radar systems.

Patent Document 1 discloses a radar device that performs phase shift keying, rotating the phase of multiple transmission signals input to multiple transmission antennas by different amounts of phase rotation for each repetition period. The radar device sets the number of phases used for phase shift keying to be greater than the number of transmission antennas. As a result, the radar device unevenly arranges peaks based on each transmission signal on the Doppler spectrum obtained by analyzing the received signal. The radar device identifies the correspondence between multiple peaks and multiple transmission antennas by using the locations on the Doppler spectrum where the peaks are unevenly arranged.

Patent No. 6881177

However, the Doppler spectrum may contain peaks derived from signal components other than the normal transmission signal. When these peaks line up alongside the normal peaks, it can be difficult to accurately identify the correspondence between multiple peaks and multiple transmitting antennas. In this case, there is a risk that an incorrect correspondence will be selected, resulting in a false detection.

An object of the present disclosure is to provide a radar system capable of suppressing false detections. Another object of the present disclosure is to provide a radar control device capable of suppressing false detections. Another object of the present disclosure is to provide a radar control method capable of suppressing false detections. Yet another object of the present disclosure is to provide a radar control program capable of suppressing false detections.

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

A first aspect of the present disclosure is a radar system having a plurality of transmit antennas, at least one receive antenna, and a processor,
The processor
transmitting, from each transmitting antenna, a transmission signal whose frequency changes over time in a repetition period and whose phase is shifted over time for each repetition period by a different amount between the transmitting antennas;
outputting sensing data correlating transmitted signals from a plurality of transmitting antennas with received signals received by a receiving antenna;
configured to run
To transmit a transmission signal is
transmitting, from each transmitting antenna, a transmission signal to which an initial phase that is changed in accordance with the transmitting antenna is assigned in addition to the shift amount;
Outputting sensing data is
Setting candidates for correspondence relationships between a plurality of peaks and a plurality of transmitting antennas in a velocity spectrum defined from received signals obtained by receiving signals from a plurality of transmitting antennas at a receiving antenna;
outputting sensing data correlated with the received signal for which a correspondence relationship is defined by the candidate when a phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is confirmed in a combination of the peak and the initial phase according to the set candidate;
Includes.

A second aspect of the present disclosure is a radar control device having a processor and controlling a radar system including a plurality of transmitting antennas and at least one receiving antenna,
The processor
transmitting, from each transmitting antenna, a transmission signal whose frequency changes over time in a repetition period and whose phase is shifted over time for each repetition period by a different amount between the transmitting antennas;
outputting sensing data correlating transmitted signals from a plurality of transmitting antennas with received signals received by a receiving antenna;
configured to run
To transmit a transmission signal is
transmitting, from each transmitting antenna, a transmission signal to which an initial phase that is changed in accordance with the transmitting antenna is assigned in addition to the shift amount;
Outputting sensing data is
Setting candidates for correspondence relationships between a plurality of peaks and a plurality of transmitting antennas in a velocity spectrum defined from received signals obtained by receiving signals from a plurality of transmitting antennas at a receiving antenna;
outputting sensing data correlated with the received signal for which a correspondence relationship is defined by the candidate when a phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is confirmed in a combination of the peak and the initial phase according to the set candidate;
Includes.

A third aspect of the present disclosure is a radar control method executed by a processor to control a radar system having a plurality of transmitting antennas and at least one receiving antenna, the method comprising:
transmitting, from each transmitting antenna, a transmission signal whose frequency changes over time in a repetition period and whose phase is shifted over time for each repetition period by a different amount between the transmitting antennas;
outputting sensing data correlating transmitted signals from a plurality of transmitting antennas with received signals received by a receiving antenna;
Including,
To transmit a transmission signal is
transmitting, from each transmitting antenna, a transmission signal to which an initial phase that is changed in accordance with the transmitting antenna is assigned in addition to the shift amount;
Outputting sensing data is
Setting candidates for correspondence relationships between a plurality of peaks and a plurality of transmitting antennas in a velocity spectrum defined from received signals obtained by receiving signals from a plurality of transmitting antennas at a receiving antenna;
outputting sensing data correlated with the received signal for which a correspondence relationship is defined by the candidate when a phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is confirmed in a combination of the peak and the initial phase according to the set candidate;
Includes.

A fourth aspect of the present disclosure provides a radar control program stored in a storage medium, the program including instructions to be executed by a processor that controls a radar system having a plurality of transmitting antennas and at least one receiving antenna, the program including:
The command is,
transmitting, from each transmitting antenna, a transmission signal whose frequency changes over time in a repetition period and whose phase is shifted over time for each repetition period by a different amount between the transmitting antennas;
outputting sensing data correlating transmitted signals from a plurality of transmitting antennas with received signals received by a receiving antenna;
Including,
To transmit a transmission signal is
transmitting, from each transmitting antenna, a transmission signal to which an initial phase that is changed in accordance with the transmitting antenna is assigned in addition to the shift amount;
To output sensing data,
Setting candidates for correspondence between a plurality of peaks and a plurality of transmitting antennas in a velocity spectrum defined from received signals obtained by receiving signals from a plurality of transmitting antennas at a receiving antenna;
When a phase difference between peaks correlated with the spatial arrangement of the transmitting antennas is confirmed in a combination of a peak and an initial phase according to the set candidate, outputting sensing data correlated with the received signal for which a correspondence relationship is defined by the candidate;
Includes.

In these first to fourth aspects, the transmission signal sent from each transmitting antenna is assigned a shift amount and initial phase for each transmitting antenna. Therefore, a peak containing a different initial phase may appear in the velocity spectrum defined from a single received signal, for each velocity corresponding to the shift amount. Therefore, if the candidates for correspondence between multiple peaks and multiple transmitting antennas are valid, a phase difference between the peaks that correlates with the spatial arrangement of the transmitting antennas can be confirmed in the velocity spectrum according to the combination of the peaks and initial phases corresponding to the candidates. Therefore, sensing data correlated with a group of received signals for which correspondences are defined in which a phase difference between the peaks that correlates with the spatial arrangement of the transmitting antennas has been confirmed can be sensing data in which the correspondence between the multiple peaks and the multiple transmitting antennas is accurately identified. Therefore, erroneous detection can be suppressed.

1 is a schematic diagram showing the overall configuration of a radar system according to a first embodiment; 3A and 3B are schematic diagrams for explaining phases assigned to transmission signals at each transmitting antenna. FIG. 2 is a block diagram showing the functional configuration of a control unit in the radar system. 4 is a flowchart showing a radar control flow according to the first embodiment. FIG. 2 is a schematic diagram for explaining a part of the processing performed by the radar system. 10A and 10B are schematic diagrams for explaining angle measurement processing when correspondence candidates are regular; 10A and 10B are schematic diagrams for explaining angle measurement processing when correspondence candidates are irregular; 10 is a flowchart showing a radar control flow according to a second embodiment. 10 is a flowchart showing a radar control flow according to a third embodiment. FIG. 10 is a schematic diagram for explaining detection of multiple targets.

Below, several embodiments of the present disclosure will be described with reference to the drawings. Note that corresponding components in each embodiment will be given the same reference numerals, and duplicate descriptions 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 that configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of multiple embodiments may also be partially combined together even if not explicitly stated, provided that there are no particular problems with the combination.

(First embodiment)
A first embodiment of the present disclosure will be described with reference to FIGS. 1 to 7 . The radar device 1 shown in FIG. 1 is mounted on a moving object such as a vehicle. The radar device 1 transmits a transmission signal to the outside world and receives the transmission signal reflected by a target T as a received signal. The radar device 1 acquires and outputs sensing data related to the target T that reflected the transmission signal by analyzing the received signal. The radar device 1 is a so-called MIMO (Multiple-Input-Multiple-Output) radar that transmits transmission signals from multiple transmission antennas TX to artificially increase the number of receiving antennas RX beyond the actual number. The radar device 1 is an example of a "radar system."

The sensing data output from the radar device 1 is input to an on-board ECU (Electronic Control Unit) via an on-board network such as CAN (Control Area Network (registered trademark)) or Ethernet (registered trademark). The on-board ECU performs various processes for autonomous driving of the vehicle and advanced driving assistance based on the acquired sensing data of each target T.

Processing based on sensing data includes, for example, collision avoidance processing and warning processing. Collision avoidance processing is processing that performs vehicle control to avoid collision with the target T by controlling the brake system, steering system, etc. based on the sensing data of each target T. Warning processing is processing that warns the driver of the possibility of a collision with the target T based on the sensing data of each target T.

As shown in FIG. 1, the radar device 1 of this embodiment includes a transceiver unit 2, a control unit 7, and a storage unit 8. The transceiver unit 2 is a processing unit that performs transmission processing of transmitted signals and reception processing of received signals. The transceiver unit 2 includes a clock oscillator 3, a signal generator 4, multiple transmission circuits 5, multiple transmission antennas TX, multiple reception antennas RX, and multiple reception circuits 6.

The clock oscillator 3 generates a periodic clock signal. The clock oscillator 3 transmits the clock signal to the signal generation unit 4 and each receiving circuit 6. The signal generation unit 4 generates a chirp signal modulated so that the frequency changes over time, for each chirp period Tc corresponding to the clock signal. The signal generation unit 4 generates a specified number of chirp signals for each measurement period Tf. The multiple generated chirp signals are distributed and output to each channel of the transmitting circuit 5 and receiving circuit 6. Note that in Figure 2, the chirp signal is shown as a so-called up-chirp signal, whose frequency increases over time. However, the chirp signal may also be a so-called down-chirp signal, whose frequency decreases over time.

In the following, the multiple chirp signals output from the signal generation unit 4 to the transmission circuit 5 and transmitted from the transmitting antenna TX may be referred to as transmission signals. Furthermore, in the following, the multiple chirp signals output to the receiving circuit 6 in response to the transmission signals may be referred to as local signals.

The transmitting circuit 5 and receiving circuit 6 are each primarily composed of semiconductor integrated circuit devices such as MMICs (Monolithic Microwave Integrated Circuits). The transmitting circuit 5 is connected to the transmitting antennas TX and outputs transmission signals to the transmitting antennas TX. The transmitting circuit 5 is equipped with the same number of phase shifters 51 and amplifiers 52 as the number of transmitting antennas TX connected to it.

The phase shifter 51 imparts a specific phase shift to the input transmission signal. More specifically, the phase shifter 51 imparts at least a phase shift by a substantially constant amount per chirp period Tc to multiple chirp signals aligned in time. For example, as shown in FIG. 2 , assume that a shift amount _{ω1 is imparted to multiple chirp signals as transmission signals transmitted from a specific transmitting antenna TX1 among multiple transmitting antennas TX. In this case, the phase of the kth chirp signal is rotated by the chirp number multiplied by the shift amount ω1 relative} to the phase before input to the phase shifter 51. As a result, the phases of the multiple chirp signals aligned in time that pass through the phase shifter 51 change linearly for each chirp period Tc. This linear phase change imparts a pseudo Doppler velocity to the chirp signals according to the shift amount. The shift amount that imparts the phase change described above may be referred to as the Doppler shift amount below. Note that in FIG. 2 , the chirp number k ranges from "1" to "N," which is the maximum number of chirp signals in the measurement period Tf. However, the chirp number k may be set to start from any number, such as "0." The chirp period Tc is an example of a "repetition period."

Each of the multiple phase shifters 51 imparts a different Doppler shift. That is, in Fig. 2, a shift amount ω2 different from the shift amount _ω1 is imparted to the multiple chirp signals transmitted from a transmitting antenna _TX2 different from the transmitting antenna TX1. Similarly, a shift amount _ωm different from the shift amounts _ω1 , _ω2 , etc. is imparted to the multiple chirp signals transmitted from a transmitting antenna TXm. As a result, the multiple transmission signals transmitted from the multiple transmitting antennas TX are subjected to so-called Doppler Division Multiplexing (DDM).

Furthermore, the phase shifter 51 can impart a specific initial phase φ _i to the chirp signal in addition to the Doppler shift amount. The phase shifter 51 imparts substantially the same initial phase to each of multiple chirp signals arranged in time. Each of the multiple phase shifters 51 imparts an initial phase that is changed depending on the transmitting antenna TX to which it is output. For example, each phase shifter 51 imparts a corresponding phase as an initial phase from a phase sequence pseudo-randomly encoded using a PN sequence or the like. The phase sequence is, for example, a sequence of phases pseudo-randomly changed between "0" and "π" depending on the transmitting antenna TX. In this case, each of the initial phases φ _{i_1} , φ _{i_1} , φ _{i_m} , etc. in the example of FIG. 2 is pseudo-randomly assigned either "0" or "π."

The phase shifter 51 may impart a preset Doppler shift amount and initial phase to the chirp signal. Alternatively, the phase shifter 51 may impart a different Doppler shift amount and initial phase between measurement periods Tf in response to a control command from the control unit 7. The amplifier 52 amplifies the transmission signal output from the phase shifter 51 and outputs it to the corresponding transmitting antenna TX.

The transmitting antenna TX converts the transmission signal supplied from the transmitting circuit 5 from an electrical signal to a radio wave signal and transmits it to the outside world. A single transmitting antenna TX is configured to include at least one or more antenna elements. For example, the transmitting antenna TX is a patch antenna equipped with multiple flat antenna elements. The antenna elements are arranged facing the ground plane on the opposite side of a dielectric substrate with a ground plane on one side. The multiple antenna elements are connected, for example, in series by a feeder line that supplies the electrical signal. Each transmission signal transmitted from each of the multiple transmitting antennas TX is given a different Doppler shift amount for each transmitting antenna TX and an initial phase that is changed according to the transmitting antenna TX by the corresponding phase shifter 51.

The receiving antenna RX receives, as a received signal, a radio wave signal that includes a transmitted signal reflected by a target T, which is a reflecting object in the outside world. Each of the multiple receiving antennas RX receives a signal 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. The components of each received signal corresponding to the transmitted signals from the multiple transmitting antennas TX that have been mixed into the mixed received signal will be referred to as received signal components.

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 6. The receiving antenna RX is, for example, a patch antenna, similar to the transmitting antenna TX, with at least one antenna element connected in series by a feeder line. The transmitting antenna TX and receiving antenna RX may also be monopole antennas, inverted-F antennas, loop antennas, or the like. In the following, multiple received signals received by multiple receiving antennas RX may be collectively referred to as a group of received signals.

The receiving circuit 6 is connected to the receiving antenna RX and acquires the received signal received by the receiving antenna RX. The receiving circuit 6 is equipped with the same number of amplifiers 61, signal mixers 62, and AD converters 63 as the number of connected receiving antennas RX.

The amplifier 61 amplifies the received signal received by the receiving antenna RX and outputs it to the signal mixer 62. The signal mixer 62 generates a beat signal by mixing the local signal from the signal generator 4 with the received signal. The generated beat signal is an interference signal that represents the frequency difference between the received signal and the local signal. The beat signal generated by the signal mixer 62 may have high-frequency components that deviate from the frequency difference between the received signal and the local signal filtered out by a low-pass filter (not shown). The beat signal is also called an IF signal.

The AD converter 63 converts the beat signal, which is an analog signal, into a digital signal. The AD converter 63 acquires the clock signal output by the clock oscillator 3, samples the beat signal at time intervals corresponding to the period of the clock signal, and digitizes it. The AD converter 63 sequentially outputs the digitized beat signal to the control unit 7.

The control unit 7 is connected to the transceiver unit 2 via at least one of the following: a LAN (Local Area Network) line, a wire harness, an internal bus, or a wireless communication line. The configuration of the control unit 7 will be described later.

The accommodation unit 8 is a housing that houses the transceiver unit 2 and the control unit 7. The accommodation unit 8 comprises a radome 81 and a case body 82. The radome 81 is formed primarily from a transparent material that allows millimeter-wave band radio waves to pass through. The radome 81 is attached to the case body 82 so as to cover the antennas TX and RX. The radome 81 protects the antennas TX and RX while allowing radio waves to pass through, enabling signals to be transmitted and received by the antennas TX and RX. The case body 82, together with the radome 81, defines an accommodation space that houses the components of the radar device 1 described above.

The control unit 7 is configured to include at least one dedicated computer. The dedicated computer that constitutes the control unit 7 may be a radar ECU (Electronic Control Unit) specialized for controlling a specific radar device 1. The dedicated computer that constitutes the control unit 7 may be a radar control ECU that controls multiple radar devices 1 mounted on a moving object. The dedicated computer that constitutes the control unit 7 may be a sensor control ECU that controls multiple sensors including the radar device 1 and other sensors such as LiDAR (Light Detection and Ranging/Laser Imaging Detection and Ranging).

The dedicated computer that constitutes the control unit 7 has at least one memory 7a and one processor 7b. The memory 7a is a storage medium that non-temporarily stores computer-readable programs and data, and is at least one type of non-transitory tangible storage medium, such as semiconductor memory, magnetic media, or optical media. Here, "storage" may refer to accumulation in which data is retained even when the radar device 1 is turned on or off, or may refer to temporary storage in which data is erased when the radar device 1 is turned on or off. The processor 7b includes at least one type of core, such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), RISC (Reduced Instruction Set Computer)-CPU, DFP (Data Flow Processor), or GSP (Graph Streaming Processor).

In the control unit 7, the processor 7b executes multiple instructions contained in a radar control program stored in the memory 7a to control the radar device 1. In this way, the control unit 7 constructs multiple functional blocks for controlling the radar device 1. The multiple functional blocks constructed in the control unit 7 include a transmission processing block 71 and a reception processing block 72, as shown in Figure 3. The control unit 7 is an example of a "radar control device."

The radar control method in which the control unit 7 controls the radar device 1 through the cooperation of these blocks 71 and 72 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. Note that each "S" in this radar control flow represents a number of steps executed by a number of commands included in the radar control program.

First, in S10, the transmission processing block 71 outputs a command to start transmission processing to the transceiver unit 2, causing the transmission signal to be transmitted from the multiple transmission antennas TX. As described above, the chirp signals that make up the transmission signal are given a different Doppler shift amount for each transmission antenna TX and an initial phase that is changed depending on the transmission antenna TX by the action of the phase shifter 51.

The transmission processing block 71 may transmit a command to start the transmission process, causing the transceiver unit 2 to transmit a transmission signal with a preset Doppler shift amount and initial phase. Alternatively, the transmission processing block 71 may sequentially set the Doppler shift amount and initial phase for each measurement period Tf and output them to the transceiver unit 2.

Next, in S20, the reception processing block 72 acquires, from each reception circuit 6, each beat signal defined from each reception signal in the reception signal group. Then, in S30, the reception processing block 72 acquires a Doppler spectrum for the beat signal defined from the reception signal received by a single reception antenna RX. The reception processing block 72 may acquire a beat signal corresponding to a specific, pre-defined single reception antenna RX. Alternatively, the reception processing block 72 may change the single reception antenna RX corresponding to the acquired beat signal for each measurement period Tf.

To go into more detail about the acquisition of the Doppler spectrum, the reception processing block 72 acquires the Doppler spectrum by performing a Fast Fourier Transform (FFT) twice on the beat signal. Through the first FFT process, the reception processing block 72 acquires a frequency spectrum (distance spectrum) for each chirp signal, which shows a peak at the frequency position corresponding to the distance to the target T. The distance spectrum data is a distance bin signal that includes information on the signal strength for each distance bin according to the distance resolution.

Furthermore, the receiver processing block 72 performs a second FFT process on a waveform in which the phases at the range bins obtained in the first FFT process for multiple chirp signals are arranged in time series. As a result of the FFT process, the receiver processing block 72 obtains, for each range bin, a frequency spectrum (Doppler spectrum) that shows a peak at a position corresponding to the Doppler velocity (relative velocity) of the target T. In this way, the receiver processing block 72 obtains a two-dimensional spectrum of the range R and the Doppler velocity V, as shown in Figure 5. The Doppler spectrum is also called a velocity spectrum, and the two-dimensional spectrum is also called an RV map. Note that for simplicity, the example in Figure 5 shows a case in which there are three transmitting antennas TX1, TX2, and TX3 and four receiving antennas RX1, RX2, RX3, and RX4.

Furthermore, in S40, the reception processing block 72 sets candidate correspondences between multiple peaks in the Doppler spectrum and multiple transmitting antennas TX. In other words, the reception processing block 72 tentatively determines which transmitting antenna TX corresponds to the transmitted signal sent from each of multiple peaks in the same distance bin of the two-dimensional spectrum.

For example, suppose a transmitted signal is reflected by a single target T and received by each receiving antenna RX. In this case, peaks resulting from each transmitted signal are detected in the velocity bin corresponding to the amount of Doppler shift imparted to each transmitted signal in the same distance bin. That is, in the example shown in Figure 5, peak P_TX1 corresponding to the transmitted signal from transmitting antenna TX1, peak P_TX2 corresponding to the transmitted signal from transmitting antenna TX2, and peak P_TX3 corresponding to the transmitted signal from transmitting antenna TX3 are detected.

Here, suppose that a peak P_S unrelated to the peaks corresponding to the transmitted signal is mixed in the same distance bin as the above-mentioned peaks P_TX1, P_TX2, and P_TX3. Such a peak P_S may be due to a spurious signal caused by a phase error occurring in each phase shifter 51, or may be due to a transmitted signal reflected by another target T, etc.

In this case, the reception processing block 72 sets candidates for the correspondence between these four peaks and the three transmitting antennas TX1, TX2, and TX3 as correspondence candidates. In other words, the reception processing block 72 selects three candidates from the four peaks that are estimated to correspond to the transmission signals transmitted from each of the transmitting antennas TX1, TX2, and TX3.

The reception processing block 72 may estimate and set correspondence candidates based on at least one of the following: the position of the speed bin in which each peak was detected, the relative positional relationship between the speed bins of the peaks, and the signal strength of each peak. Alternatively, the reception processing block 72 may randomly set correspondence candidates.

Next, in S50, the reception processing block 72 decodes the Doppler spectrum for the initial phase corresponding to the set candidate. More specifically, the reception processing block 72 extracts peaks corresponding to the corresponding candidates from the acquired Doppler spectrum, i.e., peaks selected as corresponding to the transmission signal from the transmitting antenna TX. The reception processing block 72 then performs a calculation process to cancel the initial phase corresponding to the set corresponding candidate for each extracted peak. As a result, the reception processing block 72 acquires a decoded spectrum in which the Doppler spectrum is decoded for the initial phase.

Next, in S60, the receiving processing block 72 performs angle measurement processing on the single decoded spectrum. In the angle measurement processing, the receiving processing block 72 performs a third FFT process on the single decoded spectrum. In the third FFT process, the receiving processing block 72 performs FFT processing on a waveform in which the phases of each peak in the decoded spectrum are aligned. As a result, the receiving processing block 72 obtains a frequency spectrum (angular spectrum) that shows a peak at the position of the angle of arrival of the received signal for angle A. The angle of arrival of the received signal essentially corresponds to the relative angle of the target T. Note that the FFT process in S60 is performed using a beat signal corresponding to the received signal received by a single receiving antenna RX when transmitted signals from multiple transmitting antennas TX are received. For this reason, this FFT process can also be referred to as MISO (Multiple-Input-Single-Output) angle measurement processing.

Then, in S70, the reception processing block 72 determines whether the signal-to-noise ratio at the peak of the angular spectrum falls outside the specified range. The signal-to-noise ratio is the ratio of signal strength to noise level NL. The reception processing block 72 may perform this determination, for example, for the maximum peak in the angular spectrum. Here, the specified range is the range of signal-to-noise ratios that are equal to or less than a threshold value. The threshold value is defined as the value at which the signal-to-noise ratio falls outside the specified range when the set correspondence candidates are normal, i.e., when the combination of each peak and each transmitting antenna TX is correct.

For example, as shown in FIG. 6 , assume that the correspondence candidates are set such that peak P_TX1 corresponds to transmitting antenna TX1, peak P_TX2 corresponds to transmitting antenna TX2, and peak P_TX3 corresponds to transmitting antenna TX3. In this case, the set correspondence candidates are normal. Therefore, the initial phases assigned to the phases of each peak are accurately canceled by the decoding process of S50. Therefore, essentially, only phases θ ₁ , θ ₂ , and θ ₃ derived from the arrival angles remain in the phases of each peak. In other words, the phase differences between peaks are regular phase differences that correlate with the spatial arrangement of the transmitting antennas TX. Therefore, the angular spectrum obtained by FFT processing shows peaks at the relative angles of the target T.

Therefore, when the signal-to-noise ratio of the peaks in the angular spectrum falls outside the specified range, this is an example of the phase difference between the peaks in the decoded spectrum correlating with the spatial arrangement of the transmitting antennas TX. Furthermore, when the signal-to-noise ratio of the angular spectrum falls outside the specified range, this is also an example of the phase difference between the peaks correlating with the spatial arrangement of the transmitting antennas TX being confirmed in the combination of the peaks and initial phases according to the set candidates.

On the other hand, as shown in Figure 7, suppose that the correspondence candidates set are such that peak P_S corresponds to transmitting antenna TX1, peak P_TX1 corresponds to transmitting antenna TX2, and peak P_TX2 corresponds to transmitting antenna TX3. In this case, the set correspondence candidates are irregular. Therefore, the decoding process of S50 imparts a further irregular phase to the phase of each peak. As a result, the angular spectrum obtained by FFT processing is spread without showing peaks at the relative angle of target T. If the MIMO angle measurement process described below is performed with the relationship between the peaks and transmitting antennas TX defined using irregular correspondence candidates, erroneous detection of the relative angle, and therefore of the sensing data, may occur.

In other words, the reception processing block 72 essentially determines whether the set correspondence candidate is legitimate by determining whether the signal-to-noise ratio of the peak in the angular spectrum is outside the specified range.

If it is determined that the signal-to-noise ratio is within the specified range, the flow proceeds to S80. In S80, the reception processing block 72 stops outputting the sensing data. If the processing of S70 and S80 does not confirm a phase difference between peaks that correlates with the spatial arrangement of the transmitting antenna TX, the output of the sensing data will be interrupted.

On the other hand, if S80 determines that the signal-to-noise ratio is outside the specified range, the flow proceeds to S90. In S90, the reception processing block 72 decodes the entire Doppler spectrum for the initial phase using a combination of peaks and initial phases according to the set correspondence. In other words, the reception processing block 72 obtains Doppler spectra for beat signals based on received signals at other reception antennas RX, other than the beat signal used to check the phase difference between peaks. The reception processing block 72 then extracts peaks from each Doppler spectrum and cancels the initial phase from the phase of each peak according to the set correspondence, thereby obtaining a decoded spectrum for each reception antenna RX.

Next, in S100, the reception processing block 72 performs angle measurement processing on the multiple decoded spectra. That is, the reception processing block 72 performs FFT processing on a waveform that aligns the phases of each peak in the integrated spectrum obtained by integrating the multiple decoded spectra. At this time, the reception processing block 72 defines the correspondence between each peak and each transmitting antenna TX according to the set candidates, and then performs FFT processing. As a result, the reception processing block 72 obtains an angle spectrum that shows a peak at a position corresponding to the relative angle with the target T. Note that the FFT processing in S100 is processing that is performed using a group of beat signals corresponding to a group of received signals obtained by receiving transmission signals from the multiple transmitting antennas TX at each of the multiple receiving antennas RX. For this reason, this FFT processing can also be referred to as MIMO angle measurement processing.

Furthermore, in S110, the reception processing block 72 outputs sensing data corresponding to candidates for correspondence relationships in which the phase difference between peaks correlated with the spatial arrangement of the transmitting antennas TX has been confirmed. The reception processing block 72 outputs information about the target T, such as the distance to the target T, relative speed, and relative angle, as sensing data. The distance information, relative speed information, and relative angle information are information obtained by MIMO angle measurement processing that correlates the transmitted signals from the multiple transmitting antennas TX with the received signals received by each of the multiple receiving antennas RX.

According to the first embodiment described above, the transmission signal transmitted from each transmitting antenna TX is assigned a Doppler shift amount and initial phase for each transmitting antenna TX. Therefore, in the Doppler spectrum defined from a single received signal, peaks containing different initial phases can appear for each velocity corresponding to the Doppler shift amount. For this reason, if the candidates for correspondence relationships between multiple peaks and multiple transmitting antennas TX are valid, the Doppler spectrum can confirm a phase difference between the peaks that correlates with the spatial arrangement of the transmitting antennas TX, depending on the combination of the peaks and initial phases corresponding to the candidates. Therefore, sensing data correlated with a group of received signals for which correspondence relationships are defined in which a phase difference between the peaks that correlates with the spatial arrangement of the transmitting antennas TX has been confirmed can be sensing data in which the correspondence relationships between the multiple peaks and the multiple transmitting antennas TX are accurately identified. Therefore, erroneous detection of the sensing data of the target T can be suppressed.

Furthermore, according to the first embodiment, the transmission signal is encoded with an initial phase that is changed according to the transmitting antenna TX. Then, sensing data is output when the phase difference between peaks in the decoded spectrum, in which the Doppler spectrum is decoded for the initial phase according to the set candidate, correlates with the spatial arrangement of the transmitting antennas TX. Therefore, by decoding the encoding, it is possible to reliably identify the correspondence between multiple peaks and multiple transmitting antennas TX.

Furthermore, according to the first embodiment, sensing data is output when the signal-to-noise ratio of the peak in the angular spectrum defined from the decoded spectrum falls outside the specified range. Therefore, it is possible to reliably determine whether decoding was successful or not based on the signal-to-noise ratio of the peak in the angular spectrum.

In addition, according to the first embodiment, if a phase difference between peaks that correlates with the spatial arrangement of the transmitting antennas TX is not confirmed in a combination of peaks and initial phases according to the set candidates, output of sensing data is interrupted. This makes it possible to avoid outputting sensing data that correlates with a group of received signals in which a correspondence between multiple peaks and multiple transmitting antennas TX that is likely to be irregular is defined. This makes it possible to reliably suppress erroneous detection.

Second Embodiment
As shown in FIG. 8, the second embodiment is a modification of the first embodiment.

In the radar control flow of the second embodiment, if it is determined in S70 that the signal-to-noise ratio is within a specified range, the flow proceeds to S85. In S85, the reception processing block 72 resets the correspondence candidates other than the candidates for which a negative determination was made in S70. The reception processing block 72 may reset the correspondence candidate that is estimated to be correct from multiple possible candidates excluding the candidates for which a negative determination was made. Alternatively, the reception processing block 72 may set the correspondence candidate according to a specific resetting rule, such as shifting the peak associated with the transmitting antenna TX by one on the Doppler axis.

After processing S85, the flow returns to S50. That is, in this embodiment, the reception processing block 72 resets the correspondence candidate list to search for candidates that can be determined to be valid correspondences.

According to the second embodiment described above, if a phase difference between peaks correlated with the spatial arrangement of the transmitting antennas TX is not confirmed in a combination of peaks and initial phases according to a set candidate, a phase difference between peaks correlated with the spatial arrangement of the transmitting antennas TX is confirmed in another candidate. Therefore, correspondences can be searched for until correspondences between multiple peaks and multiple transmitting antennas TX that are likely to be normal are confirmed. Therefore, false detections are suppressed and accurate sensing data can be reliably output.

(Third embodiment)
As shown in FIGS. 9 and 10, the third embodiment is a modification of the first embodiment.

In the radar control flow of the third embodiment, if it is determined in S70 that the signal-to-noise ratio is outside the specified range, the flow proceeds to S71. In S71, the reception processing block 72 adopts this candidate as the correspondence relationship to be used in decoding the Doppler spectrum and stores it in memory 7a or the like as an adopted candidate. On the other hand, if it is determined in S70 that the signal-to-noise ratio is within the specified range, the flow proceeds to S72. In S71, the reception processing block 72 rejects this candidate as the correspondence relationship to be used in decoding the Doppler spectrum and either discards the data or stores it as an rejected candidate.

After processing S71 or S72, the flow proceeds to S73. In S73, the reception processing block 72 determines whether or not the selection of whether to adopt a correspondence relationship has been completed for all patterns of combinations of peaks and transmitting antennas TX.

If it is determined that selection of all patterns has not been completed, the flow proceeds to S74. In S74, the reception processing block 72 sets another candidate correspondence relationship from among the correspondence relationship patterns for which selection has not yet been completed as the selection target. After processing S74, the flow proceeds to S50. As a result, a selection is made as to whether or not to adopt all patterns of combinations of peaks and transmitting antennas TX as correspondence relationships.

On the other hand, if it is determined in S73 that selection of all patterns has been completed, the flow proceeds to S90. In this embodiment, in S90, if there are multiple corresponding candidates for adoption, the reception processing block 72 performs the decoding process for each candidate for adoption individually.

For example, as shown in Figure 10, suppose two different targets T1 and T2 are located at the same distance. In this case, peaks P1_TX1, P1_TX2, and P1_TX3 corresponding to target T1 and peaks P2_TX1, P2_TX2, and P2_TX3 corresponding to target T2 are detected in the Doppler spectrum of the same distance bin. In such a situation, there may be multiple candidates for the corresponding relationship.

The reception processing block 72 therefore performs decoding processing, assuming that each adopted candidate corresponds to different targets T1 and T2 at the same distance. In the subsequent processing at S100, the reception processing block 72 also performs MIMO angle measurement processing for different targets T1 and T2 at the same distance, for each decoded spectrum corresponding to each adopted candidate. Then, in processing at S110, the reception processing block 72 outputs sensing data for different targets T1 and T2 at the same distance.

According to the third embodiment described above, multiple patterns of candidates are set that are assumed for the correspondence between multiple peaks and multiple transmitting antennas TX. Then, if there are multiple candidates for which a phase difference between peaks that correlates with the spatial arrangement of the transmitting antennas TX has been confirmed, sensing data is output for each candidate for which a phase difference has been confirmed. Therefore, if there are multiple candidates for which a phase difference between peaks that correlates with the spatial arrangement of the transmitting antennas TX has been confirmed, sensing data can be output for each candidate as a peak originating from a different target T. Therefore, even if peaks overlap in Doppler spectra at the same distance, it may be possible to distinguish between the overlapping peaks.

(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.

In a modified example, the reception processing block 72 in S50 may perform decoding processing for each single Doppler spectrum for the number of reception antennas RX. The reception processing block 72 may perform the processing of S60 and S70 for each single Doppler spectrum, combine the judgment results for each single Doppler spectrum, and determine whether to proceed to S80 or S90.

In a modified example, at least a portion of the processing performed in blocks 71 and 72 may be executed by a processor external to the radar device 1. For example, at least a portion of the processing may be executed by a processor of an on-board ECU mounted on a vehicle in which the radar device 1 is installed. For example, in Figures 4, 8, and 9, the processing from S30 or S40 onwards may be executed by a processor of the on-board ECU. In this case, the "radar system" is composed of the radar device 1 and the processor of the on-board ECU.

In a modified example, the radar device 1 may be equipped with only one receiving antenna RX. In this case, the receiving processing block 72 outputs sensing data correlated with the received signal received by the single receiving antenna RX. For example, if the signal-to-noise ratio of a peak in the angle spectrum defined from the decoded spectrum corresponding to the corresponding candidate falls outside a specified range, the receiving processing block 72 outputs sensing data that includes at least the relative angle of the target T corresponding to that peak.

In a modified example, the dedicated computer constituting the control unit 7 may have at least one of a digital circuit and an analog circuit as the processor 7b. Here, the digital circuit is at least one of the following types: 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). Such a digital circuit may also have memory 7a that stores a program.

In a modified example, the mobile object to which the radar device 1 is applied may be, for example, an autonomous robot capable of transporting cargo or collecting information by autonomous or remote driving. Examples of autonomous robots include autonomous vehicles.

(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, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

(Technical thought 1)
A radar system having a plurality of transmit antennas (TX), at least one receive antenna (RX), and a processor (7b),
The processor:
transmitting, from each of the transmitting antennas, a transmission signal whose frequency changes over time in a repetition period and whose phase is shifted over time by a different amount between the transmitting antennas in each of the repetition periods;
outputting sensing data correlating the transmitted signals from the plurality of transmitting antennas with received signals received by the receiving antennas;
configured to run
The transmitting of the transmission signal includes:
transmitting, from each of the transmitting antennas, the transmission signal to which an initial phase that is changed in accordance with the transmitting antenna is assigned in addition to the shift amount;
The outputting of the sensing data includes:
Setting candidates for correspondence relationships between a plurality of peaks and a plurality of the transmitting antennas in a velocity spectrum defined from the received signals obtained by receiving the transmitted signals from the plurality of the transmitting antennas at the receiving antenna;
outputting the sensing data correlated with the received signal for which the correspondence relationship is defined by the candidate when a phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is confirmed in a combination of the peak and the initial phase according to the set candidate;
A radar system including:

(Technical thought 2)
The transmitting of the transmission signal includes:
transmitting, from each of the transmitting antennas, each of the transmission signals encoded with the initial phase changed according to the transmitting antenna;
The outputting of the sensing data includes:
A radar system according to Technical Idea 1, which includes outputting the sensing data when the phase difference between the peaks in a decoded spectrum obtained by decoding the velocity spectrum for the initial phase according to the set candidate correlates with the spatial arrangement of the transmitting antennas.

(Technical thought 3)
The outputting of the sensing data includes:
A radar system according to Technical Idea 2, which includes outputting the sensing data when the signal-to-noise ratio of a peak in the angular spectrum defined from the decoded spectrum is outside a specified range on the larger side.

(Technical thought 4)
The outputting of the sensing data includes:
A radar system according to any one of Technical Ideas 1 to 3, which suspends output of the sensing data when the phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is not confirmed in the combination of the peak and the initial phase according to the set candidate.

(Technical Thought 5)
The outputting of the sensing data includes:
The radar system according to any one of Technical Ideas 1 to 3 includes, when the phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is not confirmed in a combination of the peak and the initial phase according to the set candidate, confirming the phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas in another candidate.

(Technical Thought 6)
The outputting of the sensing data includes:
setting the candidates for a plurality of patterns assumed for the correspondence relationship between the plurality of peaks and the plurality of transmitting antennas;
outputting the sensing data for each of the candidates for which the phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is confirmed when there are a plurality of the candidates for which the phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is confirmed;
A radar system according to any one of Technical Ideas 1 to 3, comprising:

Note that the above technical ideas 1 to 6 may also be implemented in the form of a radar control device, a radar control method, and a radar control program.

Claims (9)

A radar system having a plurality of transmit antennas (TX), at least one receive antenna (RX), and a processor (7b),
The processor:
transmitting, from each of the transmitting antennas, a transmission signal whose frequency changes over time in a repetition period and whose phase is shifted over time by a different amount between the transmitting antennas in each of the repetition periods;
outputting sensing data correlating the transmitted signals from the plurality of transmitting antennas with received signals received by the receiving antennas;
configured to run
The transmitting of the transmission signal includes:
transmitting, from each of the transmitting antennas, the transmission signal to which an initial phase that is changed in accordance with the transmitting antenna is assigned in addition to the shift amount;
The outputting of the sensing data includes:
Setting candidates for correspondence relationships between a plurality of peaks and a plurality of the transmitting antennas in a velocity spectrum defined from the received signals obtained by receiving the transmitted signals from the plurality of the transmitting antennas at the receiving antenna;
outputting the sensing data correlated with the received signal for which the correspondence relationship is defined by the candidate when a phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is confirmed in a combination of the peak and the initial phase according to the set candidate;
A radar system including: The transmitting of the transmission signal includes:
transmitting, from each of the transmitting antennas, each of the transmission signals encoded with the initial phase changed according to the transmitting antenna;
The outputting of the sensing data includes:
2. The radar system according to claim 1, further comprising: outputting the sensing data when the phase difference between the peaks in a decoded spectrum obtained by decoding the velocity spectrum for the initial phase according to the set candidate correlates with the spatial arrangement of the transmitting antennas. The outputting of the sensing data includes:
3. The radar system according to claim 2, further comprising outputting the sensing data when a signal-to-noise ratio of a peak in the angular spectrum defined from the decoded spectrum is outside a specified range on the larger side. The outputting of the sensing data includes:
2. The radar system according to claim 1, wherein output of the sensing data is interrupted when the phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is not confirmed in a combination of the peak and the initial phase according to the set candidate. The outputting of the sensing data includes:
2. The radar system according to claim 1, further comprising: when the phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is not confirmed in a combination of the peak and the initial phase according to the set candidate, confirming the phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas in another candidate. The outputting of the sensing data includes:
setting the candidates for a plurality of patterns assumed for the correspondence relationship between the plurality of peaks and the plurality of transmitting antennas;
outputting the sensing data for each of the candidates for which the phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is confirmed when there are a plurality of the candidates for which the phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is confirmed;
10. The radar system of claim 1, comprising: A radar control device for controlling a radar system (1) having a plurality of transmitting antennas (TX) and at least one receiving antenna (RX), the radar control device comprising:
The processor:
transmitting, from each of the transmitting antennas, a transmission signal whose frequency changes over time in a repetition period and whose phase is shifted over time for each of the repetition periods by a different amount between the transmitting antennas;
outputting sensing data correlating the transmitted signals from the plurality of transmitting antennas with received signals received by the receiving antennas;
configured to run
The transmitting of the transmission signal includes:
transmitting, from each of the transmitting antennas, the transmission signal to which an initial phase that is changed in accordance with the transmitting antenna is assigned in addition to the shift amount;
The outputting of the sensing data includes:
Setting candidates for correspondence relationships between a plurality of peaks and a plurality of the transmitting antennas in a velocity spectrum defined from the received signals obtained by receiving the transmitted signals from the plurality of the transmitting antennas at the receiving antenna;
outputting the sensing data correlated with the received signal for which the correspondence relationship is defined by the candidate when a phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is confirmed in a combination of the peaks and the initial phases according to the set candidate;
A radar control device comprising: A radar control method executed by a processor (7b) for controlling a radar system (1) having a plurality of transmit antennas (TX) and at least one receive antenna (RX), comprising:
transmitting, from each of the transmitting antennas, a transmission signal whose frequency changes over time in a repetition period and whose phase is shifted over time by a different amount between the transmitting antennas in each of the repetition periods;
outputting sensing data correlating the transmitted signals from the plurality of transmitting antennas with received signals received by the receiving antennas;
Including,
The transmitting of the transmission signal includes:
transmitting, from each of the transmitting antennas, the transmission signal to which an initial phase that is changed in accordance with the transmitting antenna is assigned in addition to the shift amount;
The outputting of the sensing data includes:
Setting candidates for correspondence relationships between a plurality of peaks and a plurality of the transmitting antennas in a velocity spectrum defined from the received signals obtained by receiving the transmitted signals from the plurality of the transmitting antennas at the receiving antenna;
outputting the sensing data correlated with the received signal for which the correspondence relationship is defined by the candidate when a phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is confirmed in a combination of the peak and the initial phase according to the set candidate;
A radar control method comprising: A radar control program stored in a storage medium (7a) and including instructions to be executed by a processor (7b) for controlling a radar system (1) having a plurality of transmitting antennas (TX) and at least one receiving antenna (RX),
The instruction:
transmitting, from each of the transmitting antennas, a transmission signal whose frequency changes over time in a repetition period and whose phase is shifted over time by a different amount between the transmitting antennas in each of the repetition periods;
outputting sensing data correlating the transmitted signals from the plurality of transmitting antennas with received signals received by the receiving antennas;
Including,
The transmitting of the transmission signal includes:
transmitting, from each of the transmitting antennas, the transmission signal to which an initial phase that is changed in accordance with the transmitting antenna is assigned in addition to the shift amount;
The outputting of the sensing data includes:
setting candidates for correspondence relationships between a plurality of peaks and a plurality of the transmitting antennas in a velocity spectrum defined from the received signals obtained by receiving the transmitted signals from the plurality of the transmitting antennas at the receiving antenna;
When a phase difference between the peaks correlated with the spatial arrangement of the transmitting antennas is confirmed in a combination of the peaks and the initial phases according to the set candidate, outputting the sensing data correlated with the received signal for which the correspondence relationship is defined by the candidate;
A radar control program including: