WO2021258358A1 - 目标检测方法、装置、雷达以及车辆 - Google Patents

目标检测方法、装置、雷达以及车辆 Download PDF

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Publication number
WO2021258358A1
WO2021258358A1 PCT/CN2020/098212 CN2020098212W WO2021258358A1 WO 2021258358 A1 WO2021258358 A1 WO 2021258358A1 CN 2020098212 W CN2020098212 W CN 2020098212W WO 2021258358 A1 WO2021258358 A1 WO 2021258358A1
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Prior art keywords
signal
target
spectrum
signal spectrum
equal
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PCT/CN2020/098212
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English (en)
French (fr)
Inventor
李德建
劳大鹏
杨晨
王犇
朱金台
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华为技术有限公司
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Priority to PCT/CN2020/098212 priority Critical patent/WO2021258358A1/zh
Priority to EP20942365.6A priority patent/EP4163671A4/en
Priority to CN202080004814.6A priority patent/CN112771401B/zh
Publication of WO2021258358A1 publication Critical patent/WO2021258358A1/zh
Priority to US18/069,577 priority patent/US20240219516A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/35—Details of non-pulse systems
    • G01S7/352—Receivers
    • G01S7/354—Extracting wanted echo-signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S13/34—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
    • G01S13/343—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal using sawtooth modulation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/42—Simultaneous measurement of distance and other co-ordinates
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/52—Discriminating between fixed and moving objects or between objects moving at different speeds
    • G01S13/536—Discriminating between fixed and moving objects or between objects moving at different speeds using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/52—Discriminating between fixed and moving objects or between objects moving at different speeds
    • G01S13/56—Discriminating between fixed and moving objects or between objects moving at different speeds for presence detection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/35—Details of non-pulse systems
    • G01S7/352—Receivers
    • G01S7/356—Receivers involving particularities of FFT processing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/93—Radar or analogous systems specially adapted for specific applications for anti-collision purposes
    • G01S13/931—Radar or analogous systems specially adapted for specific applications for anti-collision purposes of land vehicles
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/93—Radar or analogous systems specially adapted for specific applications for anti-collision purposes
    • G01S13/931—Radar or analogous systems specially adapted for specific applications for anti-collision purposes of land vehicles
    • G01S2013/9327—Sensor installation details
    • G01S2013/93271—Sensor installation details in the front of the vehicles

Definitions

  • This application relates to the field of radar technology, and in particular to a target detection method, device, radar, and vehicle.
  • Vehicle-mounted millimeter-wave radar is one of the indispensable sensors in the field of autonomous driving because of its all-weather detection capability.
  • MIMO Multiple Input Multiple Output
  • Time-Division Multiplexing (TDM) MIMO transmission mode has the advantages of simple hardware implementation and low mutual coupling effect between multiple received signals, and has become an important research direction of vehicle-mounted millimeter-wave MIMO radar.
  • Frequency Modulated Continuous Waveform FMWC is a commonly used vehicle radar transmission waveform for TDM-MIMO.
  • the vehicle-mounted millimeter-wave radar can use the frequency information and phase information of the radar echo to determine the distance, speed and angle of the target.
  • the vehicle-mounted millimeter wave radar In the actual road environment, since multiple targets have the same distance, speed or angle, the vehicle-mounted millimeter wave radar often faces the application scenario of multi-target detection on a signal spectrum (such as an angle spectrum, a speed spectrum or a ranging spectrum).
  • a signal spectrum such as an angle spectrum, a speed spectrum or a ranging spectrum.
  • the dynamic range of the signal strength of the target is very large, which easily leads to the problem of "strong masking the weak" in the multi-target detection process, that is, the target with strong signal drowns the target with weak signal, resulting in weak signal
  • the target cannot be accurately detected. Therefore, there is an urgent need for a target detection method to solve the problem of "strong and weak".
  • the embodiment of the present application provides a target detection method, which is applied to radar, and the method includes:
  • the signal spectrum according to the received signal of the receiving antenna of the radar; reconstruct the received signal corresponding to the target in the signal spectrum that is greater than or equal to the signal strength threshold.
  • the target in the signal spectrum that is greater than or equal to the signal strength threshold is the signal The target with the highest signal intensity in the spectrum; the reconstructed received signal is eliminated from the signal spectrum to obtain an updated signal spectrum, where the updated signal spectrum indicates the signal spectrum that does not contain the target; the updated signal Determine the parameters of the target greater than or equal to the signal strength threshold in the spectrum; obtain at least one of the position information or the speed information of the determined target according to the determined parameters of the target.
  • the target detection method provided in this application embodiment reconstructs the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the signal spectrum, and eliminates the reconstructed received signal on the signal spectrum, thereby avoiding the canceled received signal (strong target Signal) interference to determine the parameters of other targets (weak target signals) in the signal spectrum, thereby reducing the problem of "strong masking the weak".
  • the target greater than or equal to the signal strength threshold in the signal spectrum is the target with the highest signal strength in the signal spectrum, the target with the highest signal strength in the signal spectrum can be prevented from interfering with other targets, effectively avoiding the problem of "strong masking the weak", and The detection accuracy of this other target can be improved.
  • the radar may preset the elimination condition, eliminate the reconstructed received signal on the signal spectrum, and obtain the updated signal spectrum.
  • the process may include: after determining that the signal spectrum meets the elimination condition, The reconstructed received signal is eliminated on the signal spectrum to obtain an updated signal spectrum, and the elimination condition includes at least one of the following:
  • the amplitude of the target greater than or equal to the signal strength threshold in the signal spectrum is less than the amplitude threshold; the peak-to-average ratio of the target greater than or equal to the signal strength threshold in the signal spectrum is less than the peak-to-average ratio threshold; and, execute after acquiring the signal spectrum The number of times the received signal is eliminated and reconstructed is less than the number threshold.
  • the amplitude threshold, peak-to-average ratio threshold, and frequency threshold may all be preset thresholds, and the amplitude threshold may be the amplitude value corresponding to the smallest object detectable by the radar, which is related to the detection accuracy of the radar.
  • the method further includes:
  • the radar may not preset the elimination conditions, and start or end the execution of the target detection method in other manners. For example, after receiving the target detection instruction, start to execute the target detection method, such as executing the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the reconstructed signal spectrum, and canceling the reconstructed received signal on the signal spectrum to get updated For example, after receiving the end detection instruction, stop executing the target detection method, such as not performing the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the reconstructed signal spectrum, and in the signal spectrum The process of eliminating the reconstructed received signal and obtaining the updated signal spectrum.
  • start to execute the target detection method such as executing the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the reconstructed signal spectrum, and canceling the reconstructed received signal on the signal spectrum to get updated
  • stop executing the target detection method such as not performing the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the
  • the process of eliminating the reconstructed received signal from the signal spectrum to obtain the updated signal spectrum includes: determining the difference between the received signal corresponding to the signal spectrum and the reconstructed received signal as the updated signal
  • the signal spectrum corresponds to the signal; the updated signal spectrum is determined according to the updated signal spectrum corresponding signal.
  • the process of reconstructing the received signal corresponding to a target greater than or equal to the signal strength threshold in the signal spectrum includes: determining other parameters of the signal spectrum according to the parameters of the target greater than or equal to the signal strength threshold in the signal spectrum Parameters, the other parameters are the parameters required to reconstruct the received signal corresponding to the target greater than or equal to the signal strength threshold.
  • the other parameters include: the amplitude value corresponding to the target in the signal spectrum, and the serial number corresponding to the amplitude value One or more of the phases corresponding to the amplitude value; the radar can reconstruct the received signal corresponding to the target according to other parameters of the signal spectrum.
  • the amplitude of each element of the reconstructed received signal is equal to a preset multiple of the maximum amplitude of the signal spectrum, and the initial value of the reconstructed received signal
  • the phase is equal to the phase corresponding to the maximum value of the amplitude.
  • the preset multiple is the reciprocal of the number of receiving antennas of the radar.
  • the reconstructed received signal is equal to the product of the scaling factor and the inverse Fourier transform of the first signal spectrum, the first signal spectrum and the signal spectrum, etc. It is long, and the value of other points in the first signal spectrum is 0 except that the position, amplitude, and phase of the point where the maximum amplitude of the signal spectrum is located are the same.
  • the signal spectrum is an angle spectrum, and the parameters of the target include angle; or, the signal spectrum is a velocity measurement spectrum, and the parameters of the target include speed; or, the signal spectrum is a ranging spectrum, and the parameters of the target include distance. .
  • the aforementioned position information may include position coordinates in a designated three-dimensional coordinate system (such as an earth coordinate system), and the speed information may include the speed of the target relative to the radar (ie, the relative speed of the target) and/or the absolute speed of the target (That is, the actual speed of the target).
  • the radar can map the target to the specified three-dimensional space coordinate system according to the distance between the target and the radar (that is, the aforementioned angle obtained through the ranging spectrum) and the angle between the target and the radar (the aforementioned angle obtained through the angle spectrum). , So as to form a radar point cloud (Point Cloud), and determine the accurate position coordinates of the target according to the radar point cloud.
  • the radar may determine the speed obtained through the speed measurement spectrum as the speed of the target relative to the radar.
  • the radar may determine the absolute speed of the target based on its own speed and the speed of the target relative to the radar.
  • the present application provides a target recognition device.
  • the target recognition device may include at least one module, and the at least one module may be used to implement the target recognition method provided in the first aspect or various possible implementations of the first aspect. .
  • the present application provides a computer device including a processor and a memory.
  • the memory stores computer instructions; the processor executes the computer instructions stored in the memory, so that the computer device executes the foregoing first aspect or the methods provided by various possible implementations of the first aspect, so that the computer device deploys the foregoing first aspect or the first aspect.
  • various possible realizations of the target identification method provided.
  • the present application provides a computer-readable storage medium in which a computer program is stored, and when the computer program is executed by a processor, the first aspect or various possible implementations of the first aspect are realized Provide the target identification method.
  • this application provides a radar, which includes:
  • a transmitting antenna, a receiving antenna, a processor, and a memory where instructions are stored in the memory, and the processor executes the instructions to implement the target identification method provided by the first aspect or various possible implementations of the first aspect.
  • the present application provides a vehicle, including a vehicle body, and the radar according to any one of the fifth methods.
  • the present application provides a computer program product.
  • the computer program product includes computer instructions, and the computer instructions are stored in a computer-readable storage medium.
  • the processor of the computer device may read the computer instruction from the computer-readable storage medium, and the processor executes the computer instruction to cause the computer device to execute the foregoing first aspect or the target identification method provided by various possible implementations of the first aspect.
  • a chip is provided.
  • the chip may include a programmable logic circuit and/or program instructions. When the chip is running, it is used to implement the target recognition method as in the first aspect.
  • FIG. 1 is a schematic diagram of an application scenario of a radar provided by an embodiment of the present application
  • FIG. 2 is a schematic diagram of a frame structure of an FMWC signal provided by an embodiment of the present application.
  • FIG. 3 is a schematic flowchart of a target detection method provided by an embodiment of the application.
  • FIG. 4 is a schematic diagram of signal reception of L receiving antennas according to an embodiment of the application.
  • Fig. 5 is a schematic diagram of a fast Fourier transform principle provided by an embodiment of the application.
  • FIG. 6 is a schematic diagram of a ranging spectrum after alignment of distance parameters according to an embodiment of the application.
  • FIG. 7 is a schematic diagram of the principle of a slow time dimension operation for measuring speed according to an embodiment of the application.
  • FIG. 8 is a schematic diagram of an RD graph provided by an embodiment of this application.
  • FIG. 9 is a schematic diagram of an AOA spectrum provided by an embodiment of the present application.
  • FIG. 10 is a schematic flowchart of another target detection method provided by an embodiment of the application.
  • FIG. 11 is a schematic flowchart of yet another target detection method provided by an embodiment of this application.
  • FIG. 12 is a schematic diagram of a schematic target recognition scene where the radar is located.
  • FIG. 13 is a schematic diagram of AOA spectrum comparison provided by an embodiment of the present application.
  • FIG. 14 is a block diagram of a target detection device provided by an embodiment of the present application.
  • FIG. 15 is a block diagram of another target detection device provided by an embodiment of the present application.
  • FIG. 16 is a possible basic hardware architecture of a computer device provided by an embodiment of the present application.
  • FIG. 17 is a schematic structural diagram of a radar provided by an embodiment of the present application.
  • FIG. 18 is a schematic structural diagram of a vehicle provided by an embodiment of the present application.
  • Figure 1 is a schematic diagram of a radar target detection scenario provided by an embodiment of the present application.
  • Figure 1 assumes that the environment where the radar is located includes vehicles and people, and the radar cross section (RCS) of the vehicles and people They are 20dBsm (decibel square meters) and 0dBsm respectively.
  • the radar cross section (RCS) of the vehicles and people are 20dBsm (decibel square meters) and 0dBsm respectively.
  • the side lobe of the signal corresponding to the detected vehicle is higher than the main lobe of the signal corresponding to the person, which causes the signal corresponding to the person to be "covered”.
  • the radar recognizes the vehicle, but not the person, and the radar misses the detection of the person.
  • a target for example, a car
  • a target point to form a "point cloud” detection output.
  • a target and a target point are not distinguished, and they are collectively referred to as a target.
  • the embodiment of the present application provides a target detection method applied to radar, which can solve the problem of "strong cover weak".
  • the following briefly introduces the radar involved in the target detection method provided in the embodiment of the present application.
  • the radar in the embodiment of the present application is a millimeter wave radar
  • the millimeter wave radar is a radar that works in a millimeter wave band (millimeter wave) detection.
  • a common millimeter wave refers to a wave in the frequency domain of 30 to 300 GHz (Gigahertz), and its wavelength is 1 to 10 mm (millimeters). Since the wavelength of millimeter wave is between microwave and centimeter wave, millimeter wave radar combines some of the advantages of microwave radar and photoelectric radar.
  • the radar in the embodiment of the present application is a MIMO radar, or a single input multiple output (Single Input Multiple Output, SIMO) radar.
  • MIMO radar refers to a radar with multiple transmitting antennas and multiple receiving antennas. MIMO radar can obtain a large array aperture when the number of antennas is limited. For a MIMO radar with N transmitting antennas and L receiving antennas, where N and L are positive integers greater than 1, the MIMO radar can form N ⁇ L virtual receiving antennas. Each virtual receiving antenna corresponds to a virtual receiving channel.
  • SIMO radar refers to a radar with one transmitting antenna and multiple receiving antennas. For a SIMO radar with 1 transmitting antenna and L receiving antennas, there are a total of L physical receiving antennas. Each physical receiving antenna corresponds to a physical receiving channel.
  • the virtual receiving antenna and the physical receiving antenna are collectively referred to as receiving antennas (also referred to as RX antennas).
  • the transmitting antenna of the radar emits electromagnetic waves, and the receiving antenna receives the radar echo.
  • the electromagnetic wave emitted by the transmitting antenna of the radar can be a Frequency Modulated Continuous Waveform (FMWC).
  • FMWC is a vehicle-mounted radar transmission waveform that can achieve good pulse compression and a small intermediate frequency bandwidth.
  • TDM Time Division Modulated Continuous Waveform
  • DDM Doppler Frequency Division Multiplexing
  • CDM Code Division Multiplexing
  • the transmission mode of FMWC can also be a composite system of at least two of the above three systems for transmission.
  • the composite system can be a composite system of TDM and DDM.
  • the waveform of the FMWC signal may also have multiple types.
  • the FMWC signal is a non-stationary signal, which includes multiple Chirp (chirp) signals.
  • Chirp signal refers to a signal whose carrier frequency increases linearly within the pulse duration when the pulse is encoded.
  • FIG. 2 is a schematic diagram of a schematic FMWC signal frame structure.
  • the horizontal axis represents time, and the vertical axis represents frequency.
  • each of the N transmitting antennas transmits a chirp signal, and N is a positive integer.
  • a frame signal (also called a signal frame) of the FMWC signal includes multiple (for example, 64, 128, or 256) Chirp signals of transmission periods, and the Chirp signal of each transmission period includes N Chirp signals.
  • FIG. 2 is only a schematic frame structure of the FMWC signal of the TDM-MIMO radar.
  • the FMWC signal transmitted by the transmitting antenna may also be modified on the basis of FIG. 2.
  • the FMCW signal sent by each transmit antenna can be shifted in a designated signal domain (or signal dimension), such as a frequency shift in the frequency domain, or a time shift in the time domain; or, changing the signal in the FMCW signal The slope of.
  • the embodiment of the present application does not limit the frame structure of the FMWC signal.
  • FIG. 3 is a schematic flowchart of a target detection method provided by an embodiment of the application.
  • the target refers to an object to be detected by a radar, and the method includes:
  • S301 Transmit a signal through the transmitting antenna of the radar.
  • the radar can be a MIMO radar or a SIMO radar.
  • the radar transmits a signal through its transmitting antenna, and the transmitted signal can be an FMWC signal.
  • the frame structure can be as shown in Figure 2.
  • the receiving antenna of the radar receives the signal and performs signal processing in the same process. Therefore, the subsequent embodiments of this application take the signal receiving and processing flow of the signal transmitted by one transmitting antenna as an example for description. If the radar includes multiple transmitting antennas, the signal reception and processing procedures of the radar for each transmitting antenna can refer to the subsequent process.
  • S302 Obtain a signal spectrum according to the received signal of the receiving antenna of the radar.
  • each receiving antenna at the receiving end receives a chirp signal, so the received radar echo is L chirp signals.
  • the identification of a chirp signal sent by the transmitting end is chirp signal Tx0, and the corresponding sequence number is 1.
  • the sequence number indicates the order of the chirp signal in a frame of signals.
  • the waveform of the chirp signal Tx0 can refer to the one in Figure 2.
  • the L receiving antennas receive a total of L chirp signals Tx0, and the corresponding serial number is 1.
  • the initial signal received by the radar through the receiving antenna is an analog signal.
  • the radar can obtain a digital signal by analog-to-digital conversion of the received signal, and use the digital signal as the received signal.
  • the analog-to-digital conversion process can be signal sampling in the time domain. process.
  • the radar continuously samples each signal frame to obtain multiple sampling points, and obtain the digital signal of each signal frame.
  • the length of each signal frame may be equal to the length of the signal frame at the transmitting end, for example, the length of a Chirp signal of 64, 128, or 256 transmission cycles.
  • the foregoing analog-to-digital conversion process may be performed by an analog-to-digital conversion circuit (Analog-to-Digital Converter, ADC) in the radar.
  • ADC Analog-to-Digital Converter
  • the radar After the radar obtains the received signal, it needs to estimate the parameters of the target on the received signal.
  • the target's parameter can be angle, speed or distance.
  • the signal spectrum obtained by the receiving end is divided into angles. There are several kinds of spectrum, velocity measurement spectrum and distance measurement spectrum, etc. The methods of obtaining are as follows:
  • the ranging operation is performed to obtain the ranging spectrum corresponding to the transmitting antenna of the radar.
  • each chirp signal received by the receiving antenna corresponds to a ranging spectrum.
  • the ranging operation is to perform a range-dimensional fast Fourier transform (Fast Fourier Transform, FFT) on a chirp signal, also called Range FFT.
  • FFT range-dimensional fast Fourier transform
  • DFT Discrete Fourier Transform
  • Discrete Fourier Transform is a discrete form of Fourier Transform in both the time domain and the frequency domain.
  • the sampling transformation of is the sampling in the frequency domain of Discrete-time Fourier Transform (Discrete-time Fourier Transform, DTFT).
  • DTFT Discrete-time Fourier Transform
  • fast Fourier transform is to decompose the original multi-point sequence into a series of short sequences in turn.
  • the speed measurement operation is a slow-FFT (slow-FFT) operation. It is worth noting that the speed measurement calculation may also be other calculations, and the specific algorithm of the speed measurement calculation is not limited in the embodiment of the present application.
  • aligning the ranging spectrum corresponding to each chirp signal sent by the same transmitting antenna according to the distance parameter means that the coordinate system of the ranging spectrum corresponding to each chirp signal sent by the same transmitting antenna is overlapped correspondingly, that is, horizontal The axis and the vertical axis coincide respectively, so that the origin coincides, and the distance corresponding to the origin is 0.
  • the radar will obtain the ranging spectrum of X chirp signals with serial number 1 Tx0
  • the M distance units of the ranging spectrum of the X chirp signal Tx0 with serial number 1 are aligned respectively, and the ranging spectrum with the aligned distance parameters corresponding to the chirp signal Tx0 with serial number 1 is obtained.
  • the distance parameter alignment corresponding to the chirp signal Tx0 with serial number 1 is the distance measurement spectrum aligned with the origin of 100 groups of 1000 distance units.
  • the ranging spectrum corresponding to each chirp signal is aligned according to the distance parameter, as shown in the corresponding column in Figure 6, one column represents a chirp signal Tx0 Corresponding distance parameter alignment ranging spectrum.
  • the distance parameter alignment ranging spectrum corresponding to the chirp signal with serial number 1 as an example (ie the leftmost column in Figure 6).
  • the ranging spectrum aligned with the distance parameter includes M Each distance unit is obtained by aligning X distance units of the ranging spectrum, and M distance units correspond to M distances one-to-one.
  • the dimension in the horizontal direction is the slow time dimension.
  • the sampling points belonging to each ranging spectrum on the same distance unit are called slow-time sampling points or Doppler sampling points.
  • the speed measurement spectrum obtained by performing the speed measurement slow-FFT (slow-FFT) operation on the distance parameter alignment range measurement spectrum shown in Fig. 6 can be shown on the right side of Fig. 7, with M distance units and M speed measurement spectra There is a one-to-one correspondence, and each speed spectrum can be represented by a row of data on the right side of Figure 7.
  • A1. Determine the range-Doppler map (Range-Dopplermap, abbreviated as RD map) according to the corresponding relationship between the respective distances and the velocity measurement spectrum.
  • RD map range-Dopplermap
  • the target RD unit is the RD unit corresponding to the target, that is, the RD unit reflects the existing target.
  • the detection algorithm is used to detect the target on the RD graph, and the detection algorithm can be a Constant False Alarm Rate (CFAR) algorithm.
  • the CFAR algorithm refers to an algorithm in which the radar automatically adjusts its sensitivity when the intensity of external interference changes during the signal detection process, so that the false alarm probability of the radar remains unchanged.
  • the detection algorithm is executed separately to obtain the target RD unit on each RD pattern.
  • the RD patterns of each receiving antenna are superimposed to obtain an RD pattern, and the detection algorithm is executed on the superimposed RD pattern to obtain the target RD unit on the RD pattern.
  • the radar has L receiving antennas, and the amplitudes of the same RD unit in the RD diagrams of the L receiving antennas are directly superimposed to obtain a superimposed RD diagram.
  • the detection algorithm By executing the detection algorithm on the superimposed RD pattern, the number of times the detection algorithm is executed can be reduced, and the signal-to-noiser ratio (SNR) of the echo signal can be improved.
  • SNR signal-to-noiser ratio
  • the grid on the right side of Fig. 7 is a schematic RD diagram.
  • the ordinate of the RD diagram represents distance, and the abscissa represents speed, and M distance units correspond to M different distances.
  • Each square in Figure 7 is an RD unit.
  • each RD unit can be uniquely indicated by an RD sequence number.
  • an RD serial number may include a speed spectrum serial number and a distance serial number.
  • Figure 8 is a specific schematic diagram of the RD diagram shown on the right side of Figure 7.
  • the ordinate in Figure 8 represents the distance number
  • the abscissa represents the velocity spectrum number (or Doppler number)
  • the RD number of each RD unit is expressed as (x, y), where the abscissa value x is a speed spectrum number, which is used to identify a speed spectrum; the ordinate value y is a distance number, which is used to identify a distance. It is the aforementioned distance unit.
  • the RD unit where the black dot is located corresponds to a target, that is, the target RD unit.
  • the RD number of the target RD unit is (x1, y1), indicating that the speed spectrum number is x1, and the distance number is Is y1.
  • executing the angle estimation algorithm refers to: executing the angle estimation algorithm according to the corresponding distance and velocity measurement spectrum of the same target RD unit of all receiving antennas.
  • the range number and Doppler number corresponding to the same target RD unit of all receiving antennas can be used to execute the angle estimation algorithm.
  • the angle estimation algorithm is the Angle of Arrival (AOA) estimation algorithm, also called the Direction of Arrival (DOA) estimation algorithm, and the corresponding angle spectrum is also called the AOA spectrum.
  • the aforementioned AOA estimation algorithm may be a digital beam-forming (Digital beam-forming, DBF) algorithm, an FFT algorithm, or a DFT algorithm.
  • the signal targeted by the AOA estimation algorithm is a signal vector formed by the same RD unit of each receiving antenna.
  • TDM-MIMO radar perform the angle estimation algorithm for the same target RD unit of all receiving antennas, and before obtaining the angle spectrum, since the transmission time of each transmitting antenna is different, it is necessary to first according to the transmission interval of each transmitting antenna, Doppler phase compensation is performed on the RD units received by each receiving antenna to eliminate the Doppler phase deviation caused by the different transmission time of each transmitting antenna.
  • Fig. 9 is a schematic diagram of an AOA spectrum provided by an embodiment of the present application.
  • the horizontal axis of the AOA spectrum represents the angle in degrees, and the vertical axis represents the amplitude (amplitude), also called amplitude, and the unit is dB (decibel).
  • Figure 9 schematically shows a scene where a weak signal target (target at 0° position) is submerged by the side lobes of a strong signal target (target at 12.5° position).
  • S303 Determine, according to the signal spectrum, a parameter of the target that is greater than or equal to the signal strength threshold.
  • the signal strength of the target can be expressed in multiple ways.
  • the signal strength of the target can be expressed by the amplitude of the signal in the signal spectrum; in another optional way, the signal strength of the target
  • the signal strength can be represented by the square of the signal's amplitude in the signal spectrum.
  • the signal strength of the target can also be expressed in other ways, and any simple transformation or equivalent modification made on the basis of this application should be included in the protection scope of this application, so it will not be repeated here.
  • the radar determines the parameters of the target according to the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the signal spectrum.
  • the radar can execute one or more target detection processes, and each target detection process is used to identify targets in the signal spectrum that are greater than or equal to the signal strength threshold. For example, when the signal spectrum is greater than or equal to the signal strength When the target of the threshold is the target with the highest signal intensity in the signal spectrum, each target recognition process defaults to a target or no target. Therefore, if the target is detected, the received signal corresponding to a target is continuously identified.
  • the estimated parameters of the target can be expressed in a variety of ways.
  • the estimated target parameter is the distance, which is represented by the corresponding distance value of the target greater than or equal to the signal strength threshold in the ranging spectrum.
  • the target greater than or equal to the signal strength threshold in the ranging spectrum is the target
  • the target parameter is represented by the distance value at the largest amplitude in the ranging spectrum
  • the estimated target parameter is the speed, which is determined by the target greater than or equal to the signal strength threshold
  • the corresponding speed value indicates that when the target in the speed measurement spectrum that is greater than or equal to the signal strength threshold is the target with the highest signal strength in the speed measurement spectrum, the target parameter is represented by the speed value at the maximum amplitude in the speed measurement spectrum; for the angle spectrum, it is estimated
  • the parameter of the target is the angle, which is represented by the corresponding angle value of the target greater than or equal to the signal strength threshold in the angle spectrum.
  • the target greater than or equal to the signal strength threshold in the angle spectrum is the target with the highest signal strength in the angle spectrum
  • the target The parameter of is represented by the angle value at the maximum amplitude in the angle spectrum.
  • the radar output angle value is 12.5°; In the secondary target detection process, the angle value output by the radar is 0°.
  • the radar After the radar has determined the parameters of the target, it can output the detection result, which includes the distance, speed and/or angle corresponding to the target.
  • the principle of target recognition in the embodiments of the present application will be briefly described below. Assuming that a radar (such as MIMO radar or SIMO radar) has a total of L receiving antennas, for the same target RD unit corresponding to the L receiving antennas, the received signals of the K targets at the L receiving antennas are the target RD unit The corresponding received signal can be expressed as:
  • ⁇ i represents the angle of the i-th target, such as AOA
  • ⁇ i represents the initial phase (also called the initial phase) of the i-th target
  • T represents vector transposition.
  • Represents the steering vector corresponding to the i-th target for example, Indicates the steering vector corresponding to the first target.
  • the received signals of K targets at L receiving antennas can be:
  • ⁇ i represents the angle of the ith target, such as AOA
  • ⁇ i represents the initial phase of the ith target
  • the symbol T represents vector transpose.
  • Represents the steering vector corresponding to the i-th target for example, Indicates the steering vector corresponding to the first target.
  • each receiving antenna In the process of obtaining the angle spectrum, it is necessary to obtain the corresponding angle of each receiving antenna according to the law of the phase of the sampling point of the L receiving antennas at the same time.
  • the steering vector is used to describe the sampling of the L receiving antennas at the same time.
  • the law of the phase of a point, each element in a steering vector represents the phase of a sampling point corresponding to an antenna at the same time.
  • the antenna array formed by the receiving antennas of the radar may be a non-uniform antenna array, such as a sparse array.
  • the antenna array composed of the receiving antenna of the radar may also be a uniform linear array (ULA).
  • ULA uniform linear array
  • d can be expressed as a vector: [0 d 0 2d 0 ...(L-1)d 0 ] T , ?
  • q is the preset scaling factor
  • L is the number of receiving antennas of the radar, such as the number of physical receiving antennas in the SIMO radar or the number of virtual receiving antennas in the MIMO radar.
  • the signal wavelength refers to the wavelength of the signal emitted by the transmitting antenna.
  • the received signals of K targets at L receiving antennas can be expressed as the sum of the received signals corresponding to K targets.
  • the velocity measurement spectrum and the ranging spectrum can also be expressed as the sum of the received signals corresponding to the K targets. If the strength of the received signal corresponding to a first target is high, which affects the radar's recognition of the received signal corresponding to the second target, that is, the problem of "strong masking the weak" occurs, and the corresponding signal of the first target can be reconstructed. The signal is received, and the received signal corresponding to the first target is eliminated from the received signal, thereby avoiding interference with the received signal corresponding to the second target.
  • Each target recognition process recognizes the received signal corresponding to a target greater than or equal to the signal strength threshold, for example, a target with the highest signal strength corresponds to And eliminate the received signal obtained by the recognition from the received signal corresponding to the signal spectrum, so as to complete the accurate recognition of multiple targets.
  • This process can be called the serial interference cancellation process.
  • the process of reconstructing the received signal of the target greater than or equal to the signal strength threshold includes:
  • the radar can determine the parameters of the target greater than or equal to the signal strength threshold in the signal spectrum, it can determine other parameters of the signal spectrum based on the parameters of the target greater than or equal to the signal strength threshold in the signal spectrum.
  • the other parameters include: One or more of the amplitude value corresponding to the target in the spectrum, the sequence number corresponding to the amplitude value, and the phase corresponding to the amplitude value.
  • the other parameters are required to reconstruct the received signal corresponding to the target that is greater than or equal to the signal strength threshold Parameters: After the radar obtains other parameters of the signal spectrum, it can reconstruct the received signal corresponding to the target according to the other parameters of the signal spectrum.
  • other parameters corresponding to the reconstructed received signal y A include the maximum amplitude A of the signal spectrum and the corresponding amplitude maximum A
  • the sequence number and the phase corresponding to the maximum amplitude A One or more of.
  • the target that is not included in the updated signal spectrum refers to the target that is determined according to the signal spectrum in S303 and is greater than or equal to the signal strength threshold.
  • the target is eliminated from the signal spectrum through subsequent signal elimination operations.
  • the radar may preset the elimination condition, and when the signal spectrum meets the elimination condition, the reconstructed received signal is eliminated on the signal spectrum to obtain the updated signal spectrum.
  • the elimination condition includes at least one of the following:
  • the amplitude of the target that is greater than or equal to the signal strength threshold in the signal spectrum is less than the amplitude threshold
  • the peak-to-average ratio of targets that are greater than or equal to the signal intensity threshold in the signal spectrum is less than the peak-to-average ratio threshold
  • the number of times of performing cancellation and reconstruction of the received signal after acquiring the signal spectrum is less than the number threshold.
  • the amplitude threshold, peak-to-average ratio threshold, and frequency threshold may all be preset thresholds, and the amplitude threshold may be the amplitude value corresponding to the smallest object detectable by the radar, which is related to the detection accuracy of the radar.
  • the signal cancellation operation may not be performed, and the action is stopped.
  • the signal cancellation operation is to receive the received signal corresponding to the identified target that is greater than or equal to the signal strength threshold from the signal spectrum. The operation of cancellation in the signal.
  • the elimination condition includes that the amplitude of the target in the signal spectrum that is greater than or equal to the signal strength threshold is less than the amplitude threshold, and the signal spectrum does not meet the elimination condition, indicating that there is no signal with an amplitude less than the amplitude threshold in the signal spectrum;
  • the elimination conditions include the signal spectrum greater than or If the peak-to-average ratio of the target equal to the signal strength threshold is less than the peak-to-average ratio threshold, the signal spectrum does not meet the cancellation condition, indicating that there is no signal with the peak-to-average ratio less than the peak-to-average ratio threshold in the signal spectrum;
  • the cancellation condition includes the cancellation after acquiring the signal spectrum The number of reconstructed received signals is less than the number threshold, and the signal spectrum does not meet the elimination condition, indicating that the number of times of eliminating reconstructed received signals has reached the upper limit of the number of times.
  • the radar can set a counter for the number of times to eliminate reconstructed received signals in the designated storage space. After acquiring the signal spectrum for the first time, the number of times to eliminate reconstructed received signals can be initialized to 0. After constructing the received signal, the number of times of eliminating the reconstructed received signal is updated once. When the radar detects whether the signal spectrum reaches the elimination condition, the number of times is obtained in the designated storage space.
  • the radar may determine the difference between the received signal corresponding to the signal spectrum and the reconstructed received signal as the updated signal spectrum corresponding signal; and determine the updated signal spectrum according to the updated signal spectrum corresponding signal.
  • the process can include:
  • the signal spectrum F is obtained by processing the received signal obtained by the radar.
  • the received signal y corresponding to the signal spectrum F is obtained by processing the received initial signal.
  • the radar when the received signal corresponding to the signal spectrum F is the received signal y obtained from the initial signal processing, after the radar performs steps 301 and 302, the radar can store the received signal y, and directly obtain the stored received signal when performing B1 y.
  • the radar can record the intermediate signal obtained after each signal cancellation operation is performed, and when B1 is executed again, the stored intermediate signal y is directly obtained.
  • the radar reconstructs the received signal y A according to the determined other parameters of the signal spectrum, and the difference between the received signal y corresponding to the signal spectrum F and the reconstructed received signal y A can be used to obtain the updated signal
  • the spectrum corresponds to the signal.
  • the updated signal spectrum can be obtained by processing the signal.
  • the process of obtaining the updated signal can refer to the process of obtaining the signal spectrum according to the received signal of the receiving antenna of the radar in S302. For example, suppose the received signal corresponding to the signal spectrum is the first signal, and the updated signal spectrum corresponds to The received signal is the second signal, and the signal spectrum and the updated signal spectrum are obtained by using the same processing procedure for the first signal and the second signal, and the first signal and the second signal belong to the same signal domain. This is not repeated in the embodiment of the application.
  • the radar determines the parameters of the target according to the target in the updated signal spectrum that is greater than or equal to the signal strength threshold.
  • the target in the signal spectrum that is greater than or equal to the signal strength threshold is the signal with the highest signal strength in the signal spectrum.
  • Target is the target with the highest signal strength in the signal spectrum.
  • the target parameters are the target's distance, speed and angle.
  • the received signal corresponding to the target greater than or equal to the signal strength threshold in the reconstructed signal spectrum is repeatedly executed, and the signal greater than or equal to the signal strength threshold is determined in the updated signal spectrum.
  • the parameter process of the target until the updated signal spectrum does not meet the elimination condition. That is, when the updated signal spectrum meets the elimination condition, the process of S304 to S305 (that is, the aforementioned target recognition process) is repeated until the updated signal spectrum does not meet the elimination condition, and the action is stopped.
  • the radar can determine at least one of the position information or the speed information of the target according to the acquired parameters.
  • the parameters of the target include: at least one of angle, speed, or distance.
  • the position information may include the position coordinates in a designated three-dimensional coordinate system (such as the earth coordinate system), and the speed information may include the speed of the target relative to the radar (that is, the relative speed of the target) and/or the absolute speed of the target (that is, the target's relative speed). Actual speed).
  • the radar can map the target to the specified three-dimensional space coordinate system according to the distance between the target and the radar (that is, the angle obtained by the aforementioned ranging spectrum) and the angle between the target and the radar (that is, the angle obtained by the aforementioned angle spectrum).
  • the radar point cloud Point Cloud
  • the radar can also detect whether the signal spectrum reaches the elimination condition; when the signal spectrum does not reach the elimination condition, it means that there is no target in the signal spectrum, stop the action, that is, stop executing S304; when the signal spectrum reaches the elimination condition , Go to S304. This can reduce unnecessary calculation procedures.
  • the foregoing embodiment takes the radar preset elimination conditions as an example to illustrate the target detection method executed by the radar.
  • the radar may not preset the elimination conditions, and start or end in other ways.
  • Implementation of target detection methods For example, after receiving the target detection instruction, start to execute the target detection method, such as executing one or more steps in S301 to S308; another example, after receiving the end detection instruction, stop executing the target detection method, such as not performing the signal cancellation operation , Stop the action.
  • the sequence of the steps of the network coding method provided in the embodiments of the present application can be adjusted appropriately, and the steps can also be increased or decreased according to the situation.
  • the correspondingly determined targets are also different.
  • the signal strength thresholds of S303 and S306 may be the same or different.
  • the parameters of the target can be determined, that is, the aforementioned S303 and S306 are executed successively; or after all the targets are determined, the determined parameters can be obtained.
  • each target that is, the aforementioned S303 and S306 are executed simultaneously or separately after the radar detects that the signal spectrum reaches the elimination condition. Any person familiar with the technical field can easily think of a change method within the technical scope disclosed in this application, which should be covered by the protection scope of this application, and therefore will not be repeated.
  • the target detection method provided in this embodiment of the application reconstructs the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the signal spectrum, and eliminates the reconstructed received signal on the signal spectrum, thereby avoiding the cancellation.
  • the received signal strong target signal
  • the target greater than or equal to the signal strength threshold in the signal spectrum is the target with the highest signal strength in the signal spectrum
  • the target with the highest signal strength in the signal spectrum can be prevented from interfering with other targets, effectively avoiding the problem of "strong masking the weak", and The detection accuracy of this other target can be improved.
  • the signal spectrum can be obtained in multiple ways, for example, according to the DBF algorithm, or according to the Fourier transform algorithm.
  • the signal reconstruction method in the aforementioned S304 is also different.
  • the target in the signal spectrum that is greater than or equal to the signal strength threshold is the target with the highest signal strength in the signal spectrum as an example, and the following optional examples are used for description:
  • the amplitude of each element of the reconstructed received signal is equal to a preset multiple of the maximum amplitude of the signal spectrum, and the initial phase of the reconstructed received signal is equal to The phase corresponding to the maximum amplitude.
  • A is the maximum amplitude of the signal spectrum F
  • ⁇ is a preset value.
  • ⁇ 1/L, Indicates that the target with the highest signal strength is the initial phase of each receiving antenna. Since the DBF algorithm does not change the group delay of the output signal spectrum, Equal to the phase at the maximum amplitude of the signal spectrum F, that is, the phase corresponding to the maximum amplitude A, F(A) represents the target with the largest signal intensity in the signal spectrum F, then f A represents the frequency of the transmitted signal, and t represents the time.
  • the reconstructed received signal y A is equal to the scaling factor ⁇ and the first signal spectrum
  • the product of the inverse Fourier transform, the first signal spectrum The same length as the signal spectrum F, and the first signal spectrum Except that the position, amplitude, and phase of the point where the maximum amplitude of the signal spectrum F is located are the same, the value of the other points is 0.
  • the first signal spectrum The same length as the signal spectrum F refers to the first signal spectrum It is the same length as the signal domain corresponding to the signal spectrum F in the Fourier transform.
  • the Fourier transform algorithm can be an FFT algorithm or a DFT algorithm.
  • the inverse Fourier transform is an inverse discrete Fourier transform (Inverse Fast Fourier Transform, IFFT);
  • the Fourier transform algorithm is a DFT algorithm, the inverse Fourier transform is Inverse Discrete Fourier Transform (Inverse Discrete Fourier Transform, IDFT).
  • IFFT inverse Fast Fourier Transform
  • IDFT Inverse Discrete Fourier Transform
  • the reconstructed received signal y A is equal to the scaling factor ⁇ and the first signal spectrum
  • the product of the IFFT, the first signal spectrum The same length as the signal spectrum F, and the first signal spectrum Except that the position, amplitude, and phase of the point where the maximum amplitude of the signal spectrum F is located are the same, the value of the other points is 0.
  • the reconstructed received signal y A is expressed as:
  • ⁇ is the preset scaling factor
  • the first signal spectrum The same length as the signal spectrum F, and the first signal spectrum Except that the position, amplitude, and phase of the point where the maximum amplitude of the signal spectrum F is located are the same, the value of the other points is 0.
  • the reconstructed received signal y A is equal to the scaling factor ⁇ and the first signal spectrum
  • the product of IDFT, the first signal spectrum The same length as the signal spectrum F, and the first signal spectrum Except that the position, amplitude, and phase of the point where the maximum amplitude of the signal spectrum F is located are the same, the value of the other points is 0.
  • the reconstructed received signal y A is expressed as:
  • ⁇ is the preset scaling factor
  • the first signal spectrum The same length as the signal spectrum F, and the first signal spectrum Except that the position, amplitude, and phase of the point where the maximum amplitude of the signal spectrum F is located are the same, the value of the other points is 0.
  • the signal spectrum can be an angle spectrum, a velocity spectrum or a distance spectrum.
  • the process of the target detection method is also different.
  • the signal spectrum is the angle spectrum or the ranging spectrum as examples, and the following two optional implementation manners are used to respectively illustrate the target detection method:
  • the signal spectrum is an angular spectrum, as shown in FIG. 10, the target detection method includes:
  • S401 Transmit a signal through the transmitting antenna of the radar.
  • S403 Determine, according to the angle spectrum, the angle of the target that is greater than or equal to the signal strength threshold.
  • the parameter of the target is the angle.
  • the target in the angle spectrum that is greater than or equal to the signal strength threshold is the target with the largest signal strength in the angle spectrum, since the amplitude at the maximum signal strength in the angle spectrum is also the largest, the signal The angle ⁇ A at the maximum intensity is also equal to the angle at the maximum amplitude in the angular spectrum, and can be represented by the angle value at the maximum amplitude in the angular spectrum.
  • the radar determines the angle of the target that is greater than or equal to the signal strength threshold, it can output the detection result to indicate the angle of the target.
  • the detection result includes the angle value at the maximum amplitude.
  • S404 Reconstruct the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the signal spectrum.
  • the parameter of the target that is greater than or equal to the signal strength threshold estimated by the angle estimation algorithm is the angle.
  • the radar can reconstruct the received signal corresponding to the target that is greater than or equal to the signal strength threshold through the angle ⁇ A.
  • each receiving antenna corresponds to an RD pattern
  • the same RD unit of the L receiving antennas corresponds to an angular spectrum.
  • the method of reconstructing the received signal corresponding to a target greater than or equal to the signal strength threshold is the same.
  • the subsequent embodiments of the present application take the method of reconstructing the received signal of an angle spectrum as an example. It is explained that the reconstruction methods of other angle spectra refer to the reconstruction methods of the received signal in the one angle spectrum. In the following, the embodiments of the present application take the following examples as examples for description:
  • y represents the signal acquired by the radar.
  • the received signal y corresponding to the signal spectrum F is the received signal that describes the signal spectrum obtained by processing the received initial signal, that is, it has not undergone signal cancellation.
  • the radar determines other parameters of the angle spectrum according to the angle of the target in the angle spectrum that is greater than or equal to the signal strength threshold.
  • the other parameters include: the amplitude value of the target in the angle spectrum and the phase corresponding to the amplitude value; and according to the angle spectrum Other parameters, reconstruct the received signal corresponding to the target.
  • the aforementioned formula 3 can be used to reproduce the received signal corresponding to the target. Structured as:
  • d [d 1 d 2 d 3 ... D L ] T is the position vector of the receiving antenna, and ⁇ is the signal wavelength.
  • ⁇ A is the angle corresponding to the target with the largest signal intensity of the angle spectrum S( ⁇ )
  • means seeking amplitude, That is, the phase corresponding to the maximum amplitude A in the angle spectrum F.
  • the radar can first determine the angle corresponding to the maximum amplitude (that is, the angle corresponding to the target with the highest signal strength) ⁇ A , and then determine the phase of the target corresponding to the maximum amplitude A according to the angle ⁇ A corresponding to the maximum amplitude .
  • other parameters can be estimated according to S( ⁇ A ): A and
  • L represents the number of receiving antennas
  • the reconstructed received signal y A is equal to the scaling factor ⁇ and the first signal spectrum
  • the product of the IFFT, the first signal spectrum The same length as the signal spectrum F, and the first signal spectrum Except that the position, amplitude, and phase of the point where the maximum amplitude of the signal spectrum F is located are the same, the value of the other points is 0.
  • the point where the maximum amplitude of the signal spectrum F is located can be determined, and the point outside the point where the maximum amplitude of the signal spectrum F is located is set to 0 to obtain the first signal spectrum
  • the radar determines other parameters of the angle spectrum based on the angle of the target in the angle spectrum that is greater than or equal to the signal strength threshold.
  • the other parameters include: the amplitude value corresponding to the target in the angle spectrum, the corresponding serial number of the amplitude value, and the corresponding amplitude value According to the other parameters of the angle spectrum, the received signal corresponding to the target is reconstructed.
  • the serial number corresponding to the amplitude value is used to indicate the position of the amplitude value in the angle spectrum.
  • the radar is based on
  • the IFFT result can be expressed as:
  • N is the total number of sampling points in the angular spectrum.
  • the reconstructed received signal y A is equal to the scaling factor ⁇ and the first signal spectrum
  • the product of IDFT, the first signal spectrum The definition of is the same as the aforementioned second optional example, and the expression of the IDFT result can be the same as that of Equation 8, so it will not be repeated.
  • the process in S405 can refer to the aforementioned S305, which is not described in detail in the embodiment of the present application.
  • S406 Determine the angle of the target that is greater than or equal to the signal strength threshold in the updated angle spectrum.
  • S407 Repeat the process of reconstructing the received signal corresponding to the target greater than or equal to the signal strength threshold in the angle spectrum, and determining the angle of the target greater than or equal to the signal strength threshold in the updated angle spectrum.
  • the radar After the radar obtains the angle of the target, it can determine the position information of the target according to the obtained angle.
  • the position information may include position coordinates in a designated three-dimensional coordinate system.
  • the radar can map the target to the specified three-dimensional space coordinate system according to the distance between the target and the radar and the angle between the target and the radar (that is, the aforementioned angle obtained through the angle spectrum), thereby forming a radar point cloud, and according to the radar point The cloud determines the exact location coordinates of the target.
  • the target detection method reconstructs the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the angle spectrum, and eliminates the reconstructed received signal on the angle spectrum, thereby avoiding the cancellation.
  • the received signal interferes with other targets in the determined angle spectrum, thereby reducing the problem of “strong masking the weak”, that is, not only the weak target signal can be easily detected, but also the influence of the side lobe of the strong target signal on the weak target is avoided, which improves Detection accuracy of weak targets.
  • the target with the largest signal strength in the angle spectrum can be prevented from interfering with other targets (weak signal targets). This effectively avoids the problem of "strong masking the weak", and can also improve the detection accuracy of the other targets.
  • the signal spectrum is a velocity measurement spectrum, as shown in Figure 11, the target detection method includes:
  • S501 Transmit a signal through the transmitting antenna of the radar.
  • S502 Obtain a velocity measurement spectrum according to the received signal of the receiving antenna of the radar.
  • S503 Determine, according to the speed measurement spectrum, the speed of the target that is greater than or equal to the signal strength threshold.
  • the target parameter is speed.
  • the target in the speed measurement spectrum that is greater than or equal to the signal strength threshold is the target with the highest signal strength in the speed measurement spectrum, since the amplitude of the maximum signal strength in the speed measurement spectrum is also the largest, the signal The velocity at the maximum intensity is also equal to the velocity at the maximum amplitude in the velocity spectrum, which can be represented by the velocity value at the maximum amplitude in the velocity spectrum.
  • the radar determines the speed of the target that is greater than or equal to the signal strength threshold, it can output the detection result to indicate the speed of the target.
  • the detection result includes the speed value at the maximum amplitude.
  • S504 Reconstruct the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the signal spectrum.
  • the velocity measurement spectrum can be obtained using a slow-time dimensional FFT algorithm, and the reconstructed received signal y A can be constructed using the aforementioned formula 4.
  • the FMWC signal includes multiple chirp signals, for the signal sent by a transmitting antenna, the radar performs signal acquisition and processing ,
  • the slow time data sequence corresponding to the target that is, the velocity measurement spectrum, can be approximately expressed as:
  • A is the amplitude of the target, which is the largest amplitude in the velocity measurement spectrum
  • m is the serial number of the chirp signal in the slow time dimension
  • T is the duration of a chirp signal, also called period
  • exp() represents the natural constant e Exponential function for the base.
  • m is an arithmetic sequence with Y as the interval, and Y represents the sequence number difference corresponding to the transmission time interval.
  • Y represents the sequence number difference corresponding to the transmission time interval.
  • Y 4
  • m is a vector composed of Y values in pairs such as [1,5,9,...].
  • the same transmitting antenna transmits a chirp signal sequence with uneven time intervals, that is, the actual transmission timing of the same transmitting antenna of the MIMO radar changes, for example, the value of m is [1,3,4,7,8,10...] Vector.
  • m can be updated to an arithmetic sequence with 1 as the interval, that is, m is a vector composed of [1,2,3,...] and other pairs of values with 1 intervals, while keeping the original y(m Based on the value of the sampling point of ), update y(m) to the value of the sampling point corresponding to the serial number other than the original m, and the updated y(m) is the same length as the original y(m). It is worth noting that when the velocity measurement spectrum is obtained by the slow-time dimensional FFT algorithm, the updated y(m) and the original y(m) equal length means that the two have the same length in the slow time dimension.
  • ⁇ is the preset scaling factor
  • the first signal spectrum Is the updated y(m), for example, ⁇ 1.
  • S505 Eliminate the reconstructed received signal on the velocity measurement spectrum to obtain an updated velocity measurement spectrum, where the updated velocity measurement spectrum represents a velocity measurement spectrum that does not include the aforementioned target.
  • S506 Determine the angle of the target that is greater than or equal to the signal strength threshold in the updated angle spectrum.
  • S507 Repeat the process of reconstructing the received signal corresponding to the target greater than or equal to the signal strength threshold in the velocity measurement spectrum, and determining the angle of the target greater than or equal to the signal strength threshold in the updated velocity measurement spectrum.
  • S508 Determine the speed information of the target according to the acquired parameters of the target.
  • the radar After the radar obtains the speed of the target, it can determine the speed information of the target according to the obtained speed.
  • the speed information may include the speed of the target relative to the radar and/or the absolute speed of the target.
  • the radar may determine the speed obtained through the speed measurement spectrum as the speed of the target relative to the radar. Further, optionally, the radar may determine the absolute speed of the target based on its own speed and the speed of the target relative to the radar.
  • the target detection method reconstructs the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the velocity measurement spectrum, and eliminates the reconstructed received signal on the velocity measurement spectrum, thereby avoiding the cancellation.
  • the received signal interferes with the parameters of other targets in the velocity measurement spectrum, thereby reducing the problem of "strong masking weak".
  • the target that is greater than or equal to the signal strength threshold in the speed measurement spectrum is the target with the highest signal strength in the speed measurement spectrum
  • the target with the highest signal strength in the speed measurement spectrum strong signal target
  • the following embodiments of this application describe the actual implementation process of an exemplary target detection method. It is assumed that the signal spectrum is the AOA spectrum obtained by the FFT algorithm, and the target in the signal spectrum is greater than or equal to the signal strength threshold. It is the target with the highest signal intensity in the signal spectrum, and the target detection method includes:
  • the radar After the radar transmits the signal through the transmitting antenna of the radar, it obtains the received signal y according to the receiving antenna of the radar;
  • the radar can also detect whether the AOA spectrum meets the elimination conditions; when the AOA spectrum does not meet the elimination conditions, it means that there is no AOA spectrum.
  • the foregoing repeated execution of C4 to C10 is an iterative process of receiving signal y.
  • the signal cancellation operation (refer to C6 and C7) eliminates the received signal corresponding to the target with the highest signal strength in the speed measurement spectrum, thereby avoiding the cancellation.
  • the signal strong target signal
  • Targets greater than or equal to the signal strength threshold include not only the target with the highest signal strength in the signal spectrum, but also other targets, the processing method of other targets refers to the processing method of the target with the highest signal strength, for example, the received signal corresponding to the target
  • Both the reconstruction method and the method of eliminating the received signal corresponding to the target from the received signal corresponding to the signal spectrum can refer to the corresponding process of the target with the highest signal strength, which will not be repeated in this embodiment of the present application.
  • FIG. 12 is a schematic diagram of a schematic target recognition scene where a radar is located
  • FIG. 13 is a schematic diagram of an AOA spectrum comparison provided by an embodiment of the present application.
  • curve 1 in FIG. 13 is the AOA spectrum obtained by using the traditional target recognition method to recognize the scene shown in FIG. 12
  • curve 2 in FIG. 13 is the scene shown in FIG.
  • a schematic diagram of the AOA spectrum obtained after the target recognition process is performed twice (that is, two AOA spectrum updates have been performed). Assume that the three cameras in FIG. 12 are Target 1, Target 2, and Target 3 in the order from right to left.
  • the traditional target recognition method is used for target detection in Figure 12.
  • the main lobe of target 3 is covered by two larger targets: Affected by the side lobes of target 1 and target 2, the signal corresponding to target 3 is "covered", and the problem of "strong cover weak" appears.
  • both target 1 and target 2 after two target recognition processes, both target 1 and target 2 have attenuation of more than 20dB, while the peak attenuation of target 3 is relatively small, and the signal side lobes of target 1 and target 2 have obvious attenuation, which reduces After the influence of the side lobes of the target 1 and target 2 signals are superimposed, the detection of target 3 is easier and more accurate. Therefore, the target detection method provided by the embodiments of the present application can achieve more accurate target detection.
  • a target detection device 60 according to an embodiment of the present application, as shown in FIG. 14, is applied to radar, and the device includes:
  • the first acquiring module 601 is configured to acquire a signal spectrum according to the received signal of the receiving antenna of the radar;
  • the reconstruction module 602 is configured to reconstruct the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the signal spectrum;
  • the elimination module 603 is configured to eliminate the reconstructed received signal on the signal spectrum to obtain an updated signal spectrum, where the updated signal spectrum indicates a signal spectrum that does not include the target;
  • the determining module 604 is configured to determine a target parameter that is greater than or equal to the signal strength threshold in the updated signal spectrum
  • the second acquisition module 605 is configured to acquire at least one of the position information or the speed information of the determined target according to the determined parameters of the target.
  • the target detection device uses the reconstruction module to reconstruct the received signal corresponding to the target that is greater than or equal to the signal strength threshold in the signal spectrum, and the cancellation module eliminates the reconstructed received signal on the signal spectrum.
  • Signal so as to avoid the interference of the canceled received signal (strong target signal) on the parameters that determine other targets (weak target signals) in the signal spectrum, thereby reducing the problem of "strong masking the weak".
  • the target greater than or equal to the signal strength threshold in the signal spectrum is the target with the highest signal strength in the signal spectrum, the target with the highest signal strength in the signal spectrum can be prevented from interfering with other targets, effectively avoiding the problem of "strong masking the weak", and The detection accuracy of this other target can be improved.
  • the cancellation module 603 is configured to: after determining that the signal spectrum meets the cancellation condition, cancel the reconstructed received signal on the signal spectrum to obtain an updated signal spectrum, and the cancellation condition includes at least one of the following: The amplitude of the target greater than or equal to the signal strength threshold in the signal spectrum is less than the amplitude threshold; the peak-to-average ratio of the target greater than or equal to the signal strength threshold in the signal spectrum is less than the peak-to-average ratio threshold; and, execute after acquiring the signal spectrum The number of times the received signal is eliminated and reconstructed is less than the number threshold.
  • the device 60 further includes:
  • the processing module 606 is configured to, after determining the parameter of the target greater than or equal to the signal strength threshold in the updated signal spectrum, and after determining that the updated signal spectrum meets the elimination condition, repeat the reconstruction of the signal spectrum greater than The received signal corresponding to the target equal to or equal to the signal strength threshold, and the parameter of the target greater than or equal to the signal strength threshold is determined in the updated signal spectrum, until the updated signal spectrum does not satisfy the elimination condition.
  • the elimination module 603 is used for:
  • the difference between the received signal corresponding to the signal spectrum and the reconstructed received signal is determined as the updated signal spectrum corresponding signal; the updated signal spectrum is determined according to the updated signal spectrum corresponding signal.
  • the reconstruction module 602 is used to:
  • the other parameters include: the amplitude value corresponding to the target in the signal spectrum, the sequence number corresponding to the amplitude value, and the amplitude value One or more of the corresponding phases;
  • the received signal corresponding to the target is reconstructed.
  • the target in the signal spectrum that is greater than or equal to the signal strength threshold is the target with the highest signal strength in the signal spectrum.
  • the amplitude of each element of the reconstructed received signal is equal to a preset multiple of the maximum amplitude of the signal spectrum, and the initial value of the reconstructed received signal
  • the phase is equal to the phase corresponding to the maximum value of the amplitude.
  • the preset multiple is the reciprocal of the number of receiving antennas of the radar.
  • the reconstructed received signal is equal to the product of the scaling factor and the inverse Fourier transform of the first signal spectrum, the first signal spectrum and the signal spectrum, etc. It is long, and the value of other points in the first signal spectrum is 0 except that the position, amplitude, and phase of the point where the maximum amplitude of the signal spectrum is located are the same.
  • the signal spectrum is an angle spectrum
  • the target parameter includes an angle
  • the signal spectrum is a velocity measurement spectrum, and the target parameter includes velocity
  • the signal spectrum is a ranging spectrum
  • the parameters of the target include distance
  • FIG. 16 is a possible basic hardware architecture of a computer device 700 provided in an embodiment of the present application.
  • the computer device 700 can be used in radar.
  • the computer device 700 includes a processor 701, a memory 702, a communication interface 703, and a bus 704.
  • the number of processors 701 may be one or more, and FIG. 16 only illustrates one of the processors 701.
  • the processor 701 may be a central processing unit (CPU). If the computer device 700 has multiple processors 701, the types of the multiple processors 701 may be different or may be the same.
  • multiple processors 701 of the computer device 700 may also be integrated into a multi-core processor.
  • the memory 702 stores computer instructions and data; the memory 702 can store computer instructions and data required to implement the target identification method provided in the present application.
  • the memory 702 stores instructions for implementing the steps of the target identification method.
  • the memory 702 may be any one or any combination of the following storage media: non-volatile memory (for example, read only memory (ROM), solid state drive (SSD), hard disk (HDD), optical disk)), volatile memory.
  • the communication interface 703 may be any one or any combination of the following devices: a network interface (for example, an Ethernet interface), a wireless network card, and other devices with a network access function.
  • the communication interface 703 is used for data communication between the computer device 700 and other computer devices or terminals.
  • the bus 704 can connect the processor 701 with the memory 702 and the communication interface 703. In this way, the processor 701 can access the memory 702 through the bus 704, and can also use the communication interface 703 to interact with other computer devices or terminals.
  • the computer device 700 executes the computer instructions in the memory 702, so that the computer device 700 implements the target detection method provided in this application.
  • the embodiment of the present application provides a radar 80, which can be applied to the fields of national defense, unmanned driving, and geographic surveying and mapping. As shown in FIG. 17, the radar 80 includes:
  • the memory 804 stores instructions, and the processor 803 executes the instructions to use the target detection method provided in the embodiment of the present application.
  • the structure and function of the memory and the processor please refer to the structure and function of the processor 701 and the memory 702 corresponding to FIG. 16 respectively.
  • a computer-readable storage medium is also provided, and a computer program is stored in the computer-readable storage medium.
  • the computer program is executed by a processor, the target detection method provided in the embodiment of the present application is provided.
  • the storage medium is a memory including instructions, and the foregoing instructions can be executed by a processor of a computer device or a radar to complete the target recognition method shown in each embodiment of the present application.
  • the computer-readable storage medium may be ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, optical data storage device, etc.
  • the target detection method provided in the embodiment of the present application can be applied to a vehicle 90, as shown in FIG. 18, including: a vehicle body 901, and a radar 902 provided in the embodiment of the present application.
  • the radar 902 may be a front radar or a rear radar of the vehicle. ⁇ radar.
  • the radar may be the radar 80 in the foregoing embodiment.
  • the vehicle may also include: vehicle controller, front axle, front suspension, front wheels, transmission, transmission shaft, muffler, rear suspension, leaf springs, shock absorbers, rear wheels, brakes, rear axles
  • vehicle controller front axle, front suspension, front wheels, transmission, transmission shaft, muffler, rear suspension, leaf springs, shock absorbers, rear wheels, brakes, rear axles
  • the target detection device provided in the above embodiment executes the target detection method
  • only the division of the above-mentioned functional modules is used as an example for illustration.
  • the above-mentioned functions can be allocated to different functional modules according to needs.
  • Complete that is, divide the internal structure of the device into different functional modules to complete all or part of the functions described above.
  • the target recognition device provided in the foregoing embodiment and the target recognition method embodiment belong to the same concept. For the specific implementation process, please refer to the method embodiment, which will not be repeated here.

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Abstract

一种目标检测方法、装置、雷达以及车辆，涉及雷达技术领域。该方法包括：根据该雷达的接收天线的接收信号，获取信号谱（302）；重构该信号谱中大于或等于信号强度阈值的目标对应的接收信号（304）；在该信号谱上消除重构的接收信号，得到更新后的信号谱，其中，该更新后的信号谱表示不包含该目标的信号谱（305）；在该更新后的信号谱中确定大于或等于信号强度阈值的目标的参数（306）；根据确定的目标的参数，获取确定的目标的位置信息或速度信息中的至少一种（308）。该目标检测方法、装置、雷达以及车辆可以避免信号谱中信号强度最大的目标对其他目标的干扰，有效避免"强掩弱"问题。

Description

目标检测方法、装置、雷达以及车辆 技术领域
本申请涉及雷达技术领域，特别涉及一种目标检测方法、装置、雷达以及车辆。
背景技术
车载毫米波雷达(radar)因具有全天候的探测能力，在自动驾驶领域是不可或缺的传感器之一。为了获得高角度分辨率，使用多输入多输出(Multiple Input Multiple Output，MIMO)雷达技术可在天线数有限的情况下获得大的阵列孔径。时分多路复用(Time-Division Multiplexing，TDM)MIMO发射模式具有硬件实现简单、多路接收信号之间互耦效应低等优点，成为车载毫米波MIMO雷达的一个重要研究方向。调频连续波(Frequency Modulated Continuous Waveform，FMWC)是TDM-MIMO一种常用的车载雷达发射波形。
车载毫米波雷达可以利用雷达回波的频率信息和相位信息确定目标的距离、速度和角度。在实际道路环境中，由于多个目标具有相同的距离、速度或角度，因而车载毫米波雷达常面临一个信号谱(例如角度谱、测速谱或测距谱)上的多目标检测的应用场景。由于车载毫米波雷达的工作环境中，目标的信号强度的动态范围非常大，容易导致多目标检测过程中出现“强掩弱”问题，即信号强的目标淹没信号弱的目标，导致信号弱的目标无法准确检测。因此亟需一种目标检测方法来解决“强掩弱”的问题。
发明内容
本申请实施例提供了一种目标检测方法，应用于雷达，所述方法包括：
根据该雷达的接收天线的接收信号，获取信号谱；重构该信号谱中大于或等于信号强度阈值的目标对应的接收信号，示例的，信号谱中大于或等于信号强度阈值的目标为该信号谱中信号强度最大的目标；在该信号谱上消除重构的接收信号，得到更新后的信号谱，其中，该更新后的信号谱表示不包含该目标的信号谱；在该更新后的信号谱中确定大于或等于信号强度阈值的目标的参数；根据确定的目标的参数，获取确定的目标的位置信息或速度信息中的至少一种。
本申实施例提供的目标检测方法，通过重构信号谱中大于或等于信号强度阈值的目标对应的接收信号，并在信号谱上消除重构的接收信号，从而避免消除的接收信号(强目标信号)对确定信号谱中其他目标(弱目标信号)的参数的干扰，从而减少“强掩弱”问题。尤其在信号谱中大于或等于信号强度阈值的目标为信号谱中信号强度最大的目标时，可以避免信号谱中信号强度最大的目标对其他目标的干扰，有效避免“强掩弱”问题，还可以提高该其他目标的检测精度。
在一种可选方式中，雷达可以预先设置消除条件，在该信号谱上消除重构的接收信号，得到更新后的信号谱的过程可以包括：在确定该信号谱满足消除条件后，在该信号谱上消除重构的接收信号，得到更新后的信号谱，该消除条件包括以下至少一种：
该信号谱中的大于或等于信号强度阈值的目标的幅度小于幅度阈值；该信号谱中的大于 或等于信号强度阈值的目标的峰均比小于峰均比阈值；以及，在获取信号谱后执行该消除重构的接收信号的次数小于次数阈值。
其中，该幅度阈值、峰均比阈值和次数阈值均可以为预先设置的阈值，幅度阈值可以为雷达可检测到的最小物体所对应的幅度值，其与雷达的检测精度相关。
可选地，在该更新后的信号谱中确定大于或等于信号强度阈值的目标的参数后，该方法还包括：
在确定该更新后的信号谱满足消除条件后，重复执行该重构该信号谱中大于或等于信号强度阈值的目标对应的接收信号，以及在该更新后的信号谱中确定大于或等于信号强度阈值的目标的参数，直至更新后的信号谱不满足该消除条件。通过重复执行该重构该信号谱中大于或等于信号强度阈值的目标对应的接收信号，以及在该更新后的信号谱中确定大于或等于信号强度阈值的目标的参数的过程，可以串行识别得到信号谱中的多个信号强度较强的目标，以避免对弱信号目标的干扰。当信号谱不满足消除条件时，再进一步执行信号消除操作容易影响最终检测精度，因此通过设置该消除条件可以避免对检测精度的影响。
在另一种可选方式中，雷达也可以不预先设置消除条件，通过其他方式开始或结束目标检测方法的执行。例如在接收到目标检测指令后，开始执行目标检测方法，如执行重构信号谱中大于或等于信号强度阈值的目标对应的接收信号，以及在该信号谱上消除重构的接收信号，得到更新后的信号谱的过程；又例如，在接收到结束检测指令后，停止执行目标检测方法，例如不执行重构信号谱中大于或等于信号强度阈值的目标对应的接收信号，以及在该信号谱上消除重构的接收信号，得到更新后的信号谱的过程。
可选地，该在该信号谱上消除重构的接收信号，得到更新后的信号谱的过程，包括：将该信号谱对应的接收信号与该重构的接收信号之差，确定为更新后的信号谱对应信号；根据该更新后的信号谱对应信号确定该更新后的信号谱。
可选地，该重构该信号谱中大于或等于信号强度阈值的目标对应的接收信号的过程，包括：根据该信号谱中大于或等于信号强度阈值的目标的参数，确定该信号谱的其他参数，该其他参数为重构大于或等于信号强度阈值的目标对应的接收信号所需的参数，示例的，该其他参数包括：该信号谱中该目标对应的幅度值、该幅度值对应的序号和该幅度值对应的相位中的一种或多种；雷达可以根据该信号谱的其他参数，重构该目标对应的接收信号。
可选地，在确定该信号谱根据数字波束赋形DBF算法获取后，重构的接收信号的每个元素的幅度等于该信号谱的幅度最大值的预设倍数，重构的接收信号的初始相位等于该幅度最大值对应的相位。
示例的，该预设倍数为该雷达的接收天线的个数的倒数。
可选地，在确定该信号谱根据傅里叶变换算法获取后，重构的接收信号等于比例缩放系数与第一信号谱的傅里叶逆变换的乘积，第一信号谱与该信号谱等长，且该第一信号谱中除与该信号谱的幅度最大值所在点的位置、幅度和相位均相同之外，其他点的值为0。
可选地，该信号谱为角度谱，该目标的参数包括角度；或者，该信号谱为测速谱，该目标的参数包括速度；或者，该信号谱为测距谱，该目标的参数包括距离。
可选地，前述位置信息可以包括在指定三维坐标系(如地球坐标系)中的位置坐标，该速度信息可以包括目标相对于雷达的速度(即目标的相对速度)和/或目标的绝对速度(即目标的实际速度)。例如，雷达可以根据目标与雷达间的距离(即前述通过测距谱获取的角度) 以及目标与雷达间的角度(即前述通过角度谱获取的角度)，将目标映射到指定三维空间坐标系中，从而形成雷达点云(Point Cloud)，并根据雷达点云确定目标的准确的位置坐标。又例如，雷达可以将前述通过测速谱获取的速度确定为目标相对于雷达的速度，进一步可选地，雷达可以基于自身的速度和目标相对于雷达的速度，确定目标的绝对速度。
第二方面，本申请提供一种目标识别装置，该目标识别装置可以包括至少一个模块，该至少一个模块可以用于实现上述第一方面或者第一方面的各种可能实现提供的该目标识别方法。
第三方面，本申请提供一种计算机设备，该计算机设备包括处理器和存储器。该存储器存储计算机指令；该处理器执行该存储器存储的计算机指令，使得该计算机设备执行上述第一方面或者第一方面的各种可能实现提供的方法，使得该计算机设备部署上述第一方面或者第一方面的各种可能实现提供的该目标识别方法。
第四方面，本申请提供一种计算机可读存储介质，所述计算机可读存储介质内存储有计算机程序，所述计算机程序被处理器执行时实现第一方面或者第一方面的各种可能实现提供的该目标识别方法。
第五方面，本申请提供一种雷达，该雷达包括：
发射天线、接收天线、处理器和存储器，所述存储器中存储指令，所述处理器执行所述指令来实现如第一方面或者第一方面的各种可能实现提供的该目标识别方法。
第六方面，本申请提供一种车辆，包括：车身，以及如第五方法任一所述的雷达。
第七方面，本申请提供一种计算机程序产品，该计算机程序产品包括计算机指令，该计算机指令存储在计算机可读存储介质中。计算机设备的处理器可以从计算机可读存储介质读取该计算机指令，处理器执行该计算机指令，使得该计算机设备执行上述第一方面或者第一方面的各种可能实现提供的目标识别方法。
第八方面，提供一种芯片，该芯片可以包括可编程逻辑电路和/或程序指令，当该芯片运行时用于实现如第一方面任一该的目标识别方法。
附图说明
图1是本申请实施例提供的一种雷达的应用场景示意图；
图2是本申请实施例提供的一种FMWC信号的帧结构的示意图；
图3为本申请实施例提供的一种目标检测方法的流程示意图；
图4为本申请实施例提供的一种L个接收天线的信号接收示意图；
图5为本申请实施例提供的一种快速傅里叶变换原理示意图；
图6为本申请实施例提供的一种距离参数对齐后的测距谱的示意图；
图7为本申请实施例提供的一种测速慢时间维运算的原理示意图；
图8为本申请实施例提供的一种RD图的示意图；
图9是本申请实施例提供的一种AOA谱示意图；
图10为本申请实施例提供的另一种目标检测方法的流程示意图；
图11为本申请实施例提供的又一种目标检测方法的流程示意图；
图12是一示意性的雷达所在的目标识别场景的示意图；
图13是本申请实施例提供的一种AOA谱对比示意图；
图14是本申请实施例提供的一种目标检测装置的框图；
图15是本申请实施例提供的另一种目标检测装置的框图；
图16是本申请实施例提供的计算机设备的一种可能的基本硬件架构；
图17是本申请实施例提供的一种雷达的结构示意图；
图18是本申请实施例提供的一种车辆的结构示意图。
具体实施方式
为使本申请的原理和技术方案更加清楚，下面将结合附图对本申请实施方式作进一步地详细描述。
雷达进行多目标检测时，容易出现“强掩弱”问题。请参考图1，图1是本申请实施例提供的一种雷达的目标检测场景的示意图，图1假设雷达所在环境包括车辆和人，其中车辆和人的雷达截面积(Radar Cross Section，RCS)分别为20dBsm(分贝平方米)和0dBsm。在雷达接收的信号不进行加窗处理的情况下，检测得到的车辆对应的信号旁瓣比人对应信号的主瓣还高，如此导致人对应的信号被“掩盖”了。最终雷达识别到车辆，但未识别到人，出现雷达漏检测到人的情况。
在道路环境中的车辆、行人、建筑物都可称为雷达的目标。在高分辨率的雷达中，一个目标(例如一辆车)往往可以被分辨为多个“目标点”，形成“点云”的检测输出。本申请实施例将一个目标和目标点不加区分，统称为目标。
本申请实施例提供一种应用于雷达的目标检测方法，可以解决“强掩弱”的问题。首先，为了便于读者理解，下面对本申请实施例提供的目标检测方法所涉及的雷达进行简单介绍。
可选地，本申请实施例中的雷达为毫米波雷达，毫米波雷达是工作在毫米波波段(millimeter wave)探测的雷达。通常的毫米波是指频域处于30～300GHz(吉赫)的波，其波长为1～10mm(毫米)。由于毫米波的波长介于微波和厘米波之间，因此毫米波雷达兼具了微波雷达和光电雷达的一些优点。
可选地，本申请实施例中的雷达为MIMO雷达，或单输入多输出(Single Input Multiple Output，SIMO)雷达。其中，MIMO雷达指的是具有多个发射天线和多个接收天线的雷达。MIMO雷达可在天线数有限的情况下获得大的阵列孔径。对于一个具有N个发射天线，L个接收天线的MIMO雷达，N和L为大于1的正整数，该MIMO雷达可以形成N×L个虚拟接收天线。每一个虚拟接收天线对应一个虚拟接收通道。
SIMO雷达指的是具有一个发射天线和多个接收天线的雷达。对于一个具有1个发射天线，L个接收天线的SIMO雷达，则一共有L个物理接收天线。每一个物理接收天线对应一个物理接收通道。
为了便于说明，对于MIMO雷达和SIMO雷达，本申请后续实施例中，将虚拟接收天线和物理接收天线统称为接收天线(也称RX天线)。
其中，雷达的发射天线发射电磁波，接收天线接收雷达回波。雷达的发射天线发射的电磁波可以为调频连续波(Frequency Modulated Continuous Waveform，FMWC)，FMWC是一种车载雷达发射波形，可实现良好的脉冲压缩和较小的中频带宽。本申请实施例中，FMWC信号发射方式可以有多种。示例的，采用TDM、多普勒频分复用(Doppler frequency Division  Multiplexing，DDM)或者码分复用(Code Division Multiplexing，CDM)等制式进行发射。可选地，FMWC的发射方式还可以为采用上述三种制式中至少两种制式的复合制式进行发射，例如，该复合制式可以为TDM与DDM的复合制式。
本申请实施例中，FMWC信号的波形也可以有多种。示例的，FMWC信号为一非平稳信号，其包括多个Chirp(啁啾)信号。Chirp信号，是指对脉冲进行编码时，其载频在脉冲持续时间内线性增加的一种信号。
例如，如图2所示，图2为一种示意性的FMWC信号的帧结构的示意图。图2中横轴表示时间，纵轴表示频率。对于一个具有N个发射天线的TDM-MIMO雷达，在一个发送周期内，N个发射天线分别发送一个chirp信号，N为正整数。则FMWC信号的一帧(frame)信号(也称一个信号帧)包括多个(例如64、128或256个)发送周期的Chirp信号，每个发送周期的Chirp信号包括N个Chirp信号。
图2只是一种TDM-MIMO雷达的FMWC信号的示意性的帧结构，本申请实施例在实际实现时，发射天线发射的FMWC信号还可以在图2的基础上进行变形。可选地，每个发射天线发送的FMCW信号可在指定信号域(或称信号维度)产生移位，例如在频域产生频移，或在时域产生时移；或者，改变FMCW信号中信号的斜率。本申请实施例对FMWC信号的帧结构不做限定。
如图3所示，图3为本申请实施例提供的一种目标检测方法的流程示意图，该目标指的是雷达所需检测的对象，该方法包括：
S301、通过雷达的发射天线发射信号。
如前所述，雷达可以为MIMO雷达或SIMO雷达，雷达通过其发射天线发射信号，该发射信号可以为FMWC信号。示例的，其帧结构可以如图2所示。对于每个发射天线发射的信号，雷达的接收天线接收信号并进行信号处理的过程相同，因此，本申请后续实施例以雷达针对一个发射天线发射的信号进行信号接收以及处理流程为例进行说明，若雷达包括多个发射天线，雷达针对每个发射天线的信号进行信号接收以及处理流程均可以参考后续过程。
S302、根据雷达的接收天线的接收信号，获取信号谱。
如图4所示，对于一个具有L个接收天线的雷达，若发射端发送一个chirp信号，则接收端的每个接收天线接收一个chirp信号，因此接收的雷达回波为L个chirp信号。图4中假设发射端发送的一个chirp信号的标识为chirp信号Tx0，对应的序号为1，该序号指示chirp信号在一帧信号中的排序，该chirp信号Tx0的波形可以参考图2中的一个chirp信号的波形，则在雷达的接收端，即L个接收天线共接收到L个chirp信号Tx0，对应的序号为1。
雷达通过接收天线接收的初始信号为模拟信号，雷达可以通过将接收的信号进行模数转换，得到数字信号，将该数字信号作为接收信号，该模数转换过程可以为在时域进行信号采样的过程。示例的，雷达对每个信号帧进行连续采样得到多个采样点，得到每个信号帧的数字信号。其中，每个信号帧的长度可以与发送端的信号帧的长度相等，例如为64、128或256个发送周期的Chirp信号的长度。可选地，前述模数转换过程可以由雷达中的模数转换电路(Analog-to-Digital Converter，ADC)执行。
雷达在获取接收信号后，需要对接收信号进行目标的参数的估计，该目标的参数可以为角度、速度或距离，按照进行估计的目标的参数的不同，接收端所获取的信号谱分为角度谱、 测速谱和测距谱等几种，获取的方式分别如下：
第一种获取方式，若需要获取测距谱，则对于每个接收天线获取的数字信号，执行测距运算得到雷达的发射天线对应的测距谱。可选地，接收天线接收的每一个chirp信号对应一个测距谱。示例的，测距运算为对一个chirp信号执行距离维快速傅里叶变换(Fast Fourier Transform，FFT)，也称Range FFT。快速傅里叶变换是离散傅氏变换(Discrete Fourier Transform，DFT)的快速算法，离散傅里叶变换是傅里叶变换在时域和频域上都呈现离散的形式，用于将时域信号的采样变换为在离散时间傅里叶变换(Discrete-time Fourier Transform，DTFT)频域的采样。快速傅里叶变换的基本思想是把原始的多点序列，依次分解成一系列的短序列。
如图5所示，假设一个信号帧包括S个Chirp信号Tx0，S为大于1的整数，其通常为2的整数次幂，假设对于每个接收天线获取的一个Chirp信号Tx0，对应的数字信号包括M个采样点的采样值，则快速傅里叶变换的结果为M个数据，那么可以将这M个数据称为M个距离单元(也称距离门)，距离单元用于反映距离上的采样间隔，M个距离单元与M个距离一一对应，图5中竖直方向所在维度即为快时间维。该M个距离单元对应的信号谱即为测距谱。
第二种获取方式，若需要获取测速谱，则在获取测距谱后，将同一个发射天线发送的各个chirp信号对应的测距谱按照距离参数对齐后，进行测速运算，得到各个距离对应的测速谱(多普勒谱)。示例的，该测速运算为测速慢时间维FFT(slow-FFT)运算。值得说明的是，该测速运算还可以为其他运算，本申请实施例对测速运算的具体算法不做限定。
其中，将同一个发射天线发送的各个chirp信号对应的测距谱按照距离参数对齐后指的是将同一个发射天线发送的各个chirp信号对应的测距谱的坐标系对应重叠，也即是横轴以及纵轴分别重合，从而使得原点重合，该原点对应的距离为0。例如，参考图5，对于每个接收天线接收的某一发射天线在X个发送周期中发射的序号为1的chirp信号Tx0，雷达将获取的X个序号为1的chirp信号Tx0的测距谱的坐标系对应重叠，相应的，X个序号为1的chirp信号Tx0的测距谱的M个距离单元分别对齐，得到了序号为1的chirp信号Tx0对应的距离参数对齐的测距谱。示例的，X＝100，M＝1000，则序号为1的chirp信号Tx0对应的距离参数对齐的测距谱为100组1000个距离单元的原点对齐的测距谱。
如图6所示，对于一个信号帧长度的chirp信号，即S个chirp信号，各个chirp信号对应的测距谱按照距离参数对齐后如图6中的对应列所示，一列表示一个chirp信号Tx0对应的距离参数对齐的测距谱，以序号为1的chirp信号对应的距离参数对齐的测距谱为例(即图6中最左侧的一列)，该距离参数对齐的测距谱包括M个距离单元，每个距离单元由X个测距谱的距离单元对齐得到，M个距离单元与M个距离一一对应。图6中，水平方向所在维度即为慢时间维。同一个距离单元上分别属于每个测距谱的采样点称为慢时间采样点或多普勒采样点。
示例的，对图6所示的距离参数对齐的测距谱进行测速慢时间维FFT(slow-FFT)运算得到的测速谱可以如图7右侧所示，M个距离单元与M个测速谱一一对应，每一个测速谱可以由图7右侧的一行数据表示。
第三种获取方式，若需要获取角度谱，则在获取各个距离对应的测速谱后，分别执行以下过程：
A1、根据该各个距离与测速谱的对应关系，确定距离-多谱勒图(Range-Dopplermap，简 称RD图)，每一个接收天线对应一个RD图。
A2、对于RD图执行检测算法，得到RD图上的目标RD单元(RD cell)。
其中，目标RD单元为目标所对应的RD单元，也即是该RD单元反映了存在的目标。检测算法用于检测RD图上的目标，该检测算法可以为恒虚警率(Constant False Alarm Rate，CFAR)算法。CFAR算法指的是在信号检测过程中，当外界干扰强度变化时，雷达通过自动调整其灵敏度，使雷达的虚警概率保持不变的算法。
对RD图执行检测算法的方式可以有多种，本申请实施例以以下两种可选方式为例进行说明：
在第一种可选方式中，对于每个接收天线对应的RD图，分别执行检测算法，得到每个RD图上的目标RD单元。
在第二种可选方式中，将各个接收天线的RD图叠加得到一个RD图，对叠加后的RD图执行检测算法，得到该RD图上的目标RD单元。
示例的，假设雷达有L个接收天线，将该L个接收天线的RD图中，同一个RD单元的幅度直接叠加，得到一个叠加后的RD图。通过对叠加后的RD图执行检测算法，可以减少检测算法执行的次数，提高回波信号的信噪比(signal-to-noiseratio，SNR)。值得说明的是，同一个RD单元指的是RD图中处于相同位置的RD单元。
如图7所示，图7右侧的方格图为一示意性的RD图，该RD图的纵坐标表示距离，横坐标表示速度，M个距离单元分别对应M个不同的距离。图7中每一个方格即为一个RD单元。可选地，在RD图中，每个RD单元可以采用一个RD序号来唯一指示。例如一个RD序号可以包括一个测速谱序号和一个距离序号。如图8所示，图8是图7右侧所示的RD图的具体示意图，示例的，图8中纵坐标表示距离序号，横坐标表示测速谱序号(或称多普勒序号)，假设每个RD单元的RD序号表示为(x，y)，其中，横坐标值x为一个测速谱序号，用于标识一个测速谱；纵坐标值y为一个距离序号，用于标识一个距离，也即是前述的一个距离单元。图8中假设黑色圆点所在RD单元对应一个目标，即为目标RD单元，对其进行CFAR检测后，得到目标RD单元的RD序号为(x1，y1)，表示测速谱序号为x1，距离序号为y1。
A3、对于所有接收天线的同一个目标RD单元，执行角度估计算法，得到角度谱。也即是一个角度谱与所有接收天线的同一个目标RD单元对应。
其中，对于所有接收天线的同一个目标RD单元，执行角度估计算法指的是：根据所有接收天线的同一目标RD单元对应距离以及测速谱，执行角度估计算法。参考图8，可以采用所有接收天线的同一目标RD单元对应的距离序号和多普勒序号，执行角度估计算法。示例的，角度估计算法为到达角(Angle of Arrival，AOA)估计算法，也称到达方向(Direction of Arrival，DOA)估计算法，相应的角度谱也称AOA谱。例如，前述AOA估计算法可以是数字波束赋形(Digital beam-forming，DBF)算法、FFT算法或DFT算法等。AOA估计算法针对的信号是各个接收天线的同一个RD单元构成的信号矢量。
可选地，对于TDM-MIMO雷达，对于所有接收天线的同一个目标RD单元，执行角度估计算法，得到角度谱之前，由于各个发射天线的发送时刻不同，需要先根据各个发射天线的发送间隔，对各个接收天线接收的RD单元进行Doppler相位补偿，以消除各个发射天线的发送时刻不同带来的Doppler相位偏差。
图9是本申请实施例提供的一种AOA谱示意图。该AOA谱的横轴表示角度，单位为度，纵轴表示幅度(amplitude)，也称振幅，单位为dB(分贝)。图9示意性地示出一个弱信号目标(0°位置处的目标)被一个强信号目标(12.5°位置处的目标)的旁瓣所淹没的场景。
S303、根据信号谱确定大于或等于信号强度阈值的目标的参数。
本申请实施例中，目标的信号强度可以有多种表示方式，在一种可选方式中，目标的信号强度可以由信号谱中信号的幅度表示；在另一种可选方式中，目标的信号强度可以由信号谱中信号的幅度的平方表示。目标的信号强度还可以有其他的表示方式，任何在本申请的基础上所进行的简单变换或等同修改，均应包含在本申请的保护范围内，因此不再赘述。
在本申请实施例中，信号强度阈值可以是固定值，也可以是可变值。若该信号强度阈值为固定值，该信号强度阈值可以根据雷达的目标识别方法的应用场景设置，例如，雷达附近的环境中存在一个或多个信号强度较大的已知目标，而该已知目标为无需识别的目标，其对需要识别的目标产生了干扰，则可以基于该已知目标对应的信号强度设置信号强度阈值，以在后续过程中，在信号谱中消除该已知目标。若该信号强度阈值为可变值，该信号强度阈值也可以根据雷达的目标识别方法的应用场景动态设置，例如，该信号强度阈值R满足信号强度设置公式：R＝E-T，其中，E为当前的信号谱中最大信号强度值，T为预设强度值。该最大信号强度值M随着信号谱的更新而更新。
可选地，雷达根据信号谱中的大于或等于信号强度阈值的目标对应的接收信号确定目标的参数。示例的，信号谱中大于或等于信号强度阈值的目标为该信号谱中信号强度最大的目标，也即是前述信号强度设置公式满足：R＝E，即T＝0。
在本申请实施例中，雷达可以执行一次或多次目标检测流程，每次目标检测流程用于识别信号谱中大于或等于信号强度阈值的目标，示例的，当信号谱中大于或等于信号强度阈值的目标为该信号谱中信号强度最大的目标时，每次目标识别流程默认存在一个目标或不存在目标。因此若检测得到目标，则继续识别出一个目标对应的接收信号。
对于不同信号谱，估计得到的目标的参数可以通过多种方式表示。例如，对于测距谱，估计得到的目标的参数为距离，其由测距谱中大于或等于信号强度阈值的目标对应距离值表示，当测距谱中大于或等于信号强度阈值的目标为该测距谱中信号强度最大的目标时，目标的参数由测距谱中幅度最大处的距离值表示；对于测速谱，估计得到的目标的参数为速度，其由大于或等于信号强度阈值的目标对应速度值表示，当测速谱中大于或等于信号强度阈值的目标为该测速谱中信号强度最大的目标时，目标的参数由测速谱中幅度最大处的速度值表示；对于角度谱，估计得到的目标的参数为角度，其由角度谱中大于或等于信号强度阈值的目标对应角度值表示，当角度谱中大于或等于信号强度阈值的目标为该角度谱中信号强度最大的目标时，目标的参数由角度谱中幅度最大处的角度值表示。如图9所示，当角度谱中大于或等于信号强度阈值的目标为该角度谱中信号强度最大的目标时，在第一次目标检测流程中，雷达输出的角度值为12.5°；在第二次目标检测流程中，雷达输出的角度值为0°。
雷达在确定了目标的参数之后，可以输出检测结果，该检测结果包括目标对应的距离、速度和/或角度。
S304、重构信号谱中大于或等于信号强度阈值的目标对应的接收信号。
为了便于读者理解，下面对本申请实施例进行目标识别的原理进行简单说明。假设雷达 (如MIMO雷达或SIMO雷达)一共有L个接收天线，对于L个接收天线对应的同一个目标RD单元，K个目标的在L个接收天线的接收信号，也即是该目标RD单元对应的接收信号可以表示为：
Figure PCTCN2020098212-appb-000001
其中，L≥1，K≥1，a i表示第i个目标的幅度，1≤i≤K，d＝[d 1d 2d 3…d L] T是接收天线的位置矢量，即接收天线所组成的天线阵列中各个阵元的位置，其元素d p,p＝1,2,…,L表示第p个接收天线的位置。θ i表示第i个目标的角度，如AOA，φ i表示第i个目标的初始相位(也称初相)，符号T表示求矢量转置。
Figure PCTCN2020098212-appb-000002
表示第i个目标对应的导向矢量(steering vector)，例如，
Figure PCTCN2020098212-appb-000003
表示第1个目标对应的导向矢量。
或者，对于L个接收天线的同一个目标RD单元，K个目标的在L个接收天线的接收信号可以为：
Figure PCTCN2020098212-appb-000004
其中，L≥1，K≥1，a i表示第i个目标的幅度，1≤i≤K，d＝[d 1d 2d 3…d L] T是接收天线的位置矢量，其元素d p,p＝1,2,…,L表示第p个接收天线的位置。θ i表示第i个目标的角度，如AOA，φ i表示第i个目标的初始相位，符号T表示矢量转置。
Figure PCTCN2020098212-appb-000005
表示第i个目标对应的导向矢量，例如，
Figure PCTCN2020098212-appb-000006
表示第1个目标对应的导向矢量。
在进行角度谱的获取过程中，需要根据L个接收天线在同一个时刻的采样点的相位的规律来获取各个接收天线对应的角度，导向矢量用于描述L个接收天线在同一个时刻的采样点的相位的规律，一个导向矢量中的每个元素表示同一时刻的一个天线对应的一个采样点的相位。
本申请实施例中，雷达的接收天线所组成的天线阵列可以为非均匀天线阵列，如稀疏阵列(sparse array)。雷达的接收天线所组成的天线阵列还可以为均匀线性阵列(Uniform Linear Array，ULA)。以雷达的接收天组成的天线阵列为ULA为例，前述公式一和公式二中，d可表示为矢量：[0 d 02d 0…(L-1)d 0] T，
Figure PCTCN2020098212-appb-000007
？是信号波长，q是预设的比例缩放系数，L是雷达的接收天线的个数，如SIMO雷达中物理接收天线或MIMO雷达中虚拟接收天线的个数。其中，该信号波长指的是发射天线发射的信号的波长。q用于调整视场角，示例的，0.9≤q≤1.1，通常q＝1。
由上述公式一或公式二可知，对于L个接收天线的同一个目标RD单元，K个目标的在L个接收天线的接收信号可以表示为K个目标对应的接收信号之和，同理的，测速谱和测距谱也可以表示为K个目标对应的接收信号之和。如果一个第一目标对应的接收信号的强度较高，影响了雷达对第二目标对应的接收信号的识别，也即出现了“强掩弱”的问题，可以通过重构该第一目标对应的接收信号，并从接收信号中消除该第一目标对应的接收信号，从而避免对第二目标对应的接收信号的干扰。若雷达的可识别范围内存在多个目标，可以执行一次或多次目标识别流程，每次目标识别流程识别得到大于或等于信号强度阈值的目标对应的接收信号，例如一个信号强度最大的目标对应的接收信号，并将该识别得到的接收信号从信号谱对应的接收信号中消除，从而完成多个目标的精准识别。该过程可以称为串行干扰消除 过程。
本申请实施例在实际实现时，需要重构信号谱中大于或等于信号强度阈值的目标对应的接收信号，以对重构的接收信号进行消除。该重构大于或等于信号强度阈值的目标的接收信号的过程包括：
由于雷达可以在信号谱中确定出大于或等于信号强度阈值的目标的参数，则可以根据信号谱中大于或等于信号强度阈值的目标的参数，确定信号谱的其他参数，该其他参数包括：信号谱中目标对应的幅度值、该幅度值对应的序号和该幅度值对应的相位中的一种或多种，该其他参数为重构大于或等于信号强度阈值的目标对应的接收信号所需的参数；雷达获取了信号谱的其他参数后，可以根据信号谱的其他参数，重构目标对应的接收信号。
示例的，信号谱中大于或等于信号强度阈值的目标为信号谱中信号强度最大的目标时，重构的接收信号y A对应的其他参数包括信号谱的幅度最大值A、幅度最大值A对应的序号和幅度最大值A对应的相位
Figure PCTCN2020098212-appb-000008
中的一种或多种。
S305、在信号谱上消除重构的接收信号，得到更新后的信号谱，其中，该更新后的信号谱表示不包含前述目标的信号谱。
需要说明的是，该更新后的信号谱所不包含的目标指的是前述S303中根据信号谱确定的大于或等于信号强度阈值的目标。该目标通过后续的信号消除操作从信号谱中消除。
示例的，雷达可以预先设置消除条件，当信号谱满足消除条件，在信号谱上消除重构的接收信号，得到更新后的信号谱。该消除条件包括以下至少一种：
信号谱中的大于或等于信号强度阈值的目标的幅度小于幅度阈值；
信号谱中的大于或等于信号强度阈值的目标的峰均比小于峰均比阈值；
以及，在获取信号谱后执行消除重构的接收信号的次数小于次数阈值。
其中，该幅度阈值、峰均比阈值和次数阈值均可以为预先设置的阈值，幅度阈值可以为雷达可检测到的最小物体所对应的幅度值，其与雷达的检测精度相关。
值得说明的是，当信号谱不满足消除条件，可以不执行信号消除操作，停止动作，该信号消除操作为将识别得到的大于或等于信号强度阈值的目标对应的接收信号从信号谱对应的接收信号中消除的操作。例如，消除条件包括信号谱中大于或等于信号强度阈值的目标的幅度小于幅度阈值，则信号谱不满足消除条件说明信号谱中不存在幅度小于幅度阈值的信号；消除条件包括信号谱中大于或等于信号强度阈值的目标的峰均比小于峰均比阈值，则信号谱不满足消除条件说明信号谱中不存在峰均比小于峰均比阈值的信号；消除条件包括在获取信号谱后执行消除重构的接收信号的次数小于次数阈值，则信号谱不满足消除条件说明消除重构的接收信号的次数达到了次数上限。当信号谱不满足消除条件时，再进一步执行信号消除操作容易影响最终检测精度，因此通过设置该消除条件可以避免对检测精度的影响。需要说明的是，雷达可以在指定存储空间设置消除重构的接收信号的次数的计数器，在首次获取信号谱后，可以将消除重构的接收信号的次数初始化为0，在每执行一次消除重构的接收信号后，更新一次消除重构的接收信号的次数，雷达在检测信号谱是否达到消除条件时，在该指定存储空间获取该次数。
在S305中，雷达可以将信号谱对应的接收信号与重构的接收信号之差，确定为更新后的信号谱对应信号；并根据更新后的信号谱对应信号确定更新后的信号谱。该过程可以包括：
B1、获取信号谱F对应的接收信号y。
信号谱F是由雷达获取的接收信号处理得到的，当该信号谱是雷达根据接收天线所接收的信号处理得到的，则信号谱F对应的接收信号y为对接收的初始信号经过处理得到的描述该信号谱的接收信号，即未经过信号消除操作的初始接收信号；当该信号谱F是由该初始接收信号经过至少一次信号消除操作得到的中间信号，则信号谱F对应的接收信号为该中间信号。
可选地，当信号谱F对应的接收信号为初始信号处理得到的接收信号y，在雷达执行步骤301和302后，雷达可以存储该接收信号y，在执行B1时，直接获取存储的接收信号y。
当信号谱F对应的接收信号为中间信号y，雷达可以在每执行一次信号消除操作后记录得到的中间信号，在再次执行B1时，直接获取存储的中间信号y。
B2、将信号谱F对应的接收信号y与重构的接收信号y A之差，确定为更新后的信号谱对应信号。
如S304所述，雷达根据确定的信号谱的其他参数，重构的接收信号y A，将信号谱F对应的接收信号y与重构的接收信号y A做差，即可得到更新后的信号谱对应信号。
B3、根据更新后的信号谱对应信号确定更新后的信号谱。
雷达在获取了更新后的信号谱所对应的接收信号后，可以通过对该信号进行处理得到更新后的信号谱。该获取更新后的信号的过程可以参考前述S302中根据雷达的接收天线的接收信号，获取信号谱的过程，示例的，假设信号谱对应的接收信号为第一信号，更新后的信号谱对应的接收信号为第二信号，则信号谱和更新后的信号谱是对第一信号和第二信号分采用相同的处理流程处理得到的，第一信号和第二信号属于相同的信号域。本申请实施例对此不做赘述。
S306、在更新后的信号谱中确定大于或等于信号强度阈值的目标的参数。
可选地，雷达根据更新后的信号谱中大于或等于信号强度阈值的目标确定该目标的参数，可选地，信号谱中大于或等于信号强度阈值的目标为该信号谱中信号强度最大的目标。对应于测距谱、测速谱和角度谱，目标的参数分别为目标的距离、速度和角度。该确定信号谱中大于或等于信号强度阈值的目标的参数的过程可以参考前述S303，本申请实施例对此不做赘述。
S307、重复执行重构信号谱中大于或等于信号强度阈值的目标对应的接收信号，以及在更新后的信号谱中确定大于或等于信号强度阈值的目标的参数。
可选地，当更新后的信号谱满足消除条件，重复执行重构信号谱中大于或等于信号强度阈值的目标对应的接收信号，以及在更新后的信号谱中确定大于或等于信号强度阈值的目标的参数过程，直至更新后的信号谱不满足消除条件。也即是，当更新后的信号谱满足消除条件，重复S304至S305(即前述目标识别流程)的过程，直至更新后的信号谱不满足消除条件，停止动作。
S308、根据确定的目标的参数，获取确定的目标的位置信息或速度信息中的至少一种。
雷达在获取目标的参数后，可以根据获取的参数，确定目标的位置信息或速度信息中的至少一种。目标的参数包括：角度、速度或距离中的至少一种。该位置信息可以包括在指定三维坐标系(如地球坐标系)中的位置坐标，该速度信息可以包括目标相对于雷达的速度(即目标的相对速度)和/或目标的绝对速度(即目标的实际速度)。例如，雷达可以根据目标与雷达间的距离(即前述通过测距谱获取的角度)以及目标与雷达间的角度(即前述通过角度 谱获取的角度)，将目标映射到指定三维空间坐标系中，从而形成雷达点云(Point Cloud)，并根据雷达点云确定目标的准确的位置坐标。
值得说明的是，在S304之前，雷达还可以检测信号谱是否达到消除条件；当信号谱未达到消除条件，说明信号谱中不存在目标，停止动作，即停止执行S304；当信号谱达到消除条件，执行S304。如此可以减少不必要的计算流程。
需要说明的是，前述实施例以雷达预先设置消除条件为例对雷达执行的目标检测方法进行说明，本申请实施例在实际实现时，雷达也可以不预先设置消除条件，通过其他方式开始或结束目标检测方法的执行。例如在接收到目标检测指令后，开始执行目标检测方法，如执行S301至S308中的一步或多步；又例如，在接收到结束检测指令后，停止执行目标检测方法，例如不执行信号消除操作，停止动作。
并且，本申请实施例提供的网络编码方法步骤的先后顺序可以进行适当调整，步骤也可以根据情况进行相应增减，例如，S303和S306中由于信号谱不同，相应确定的目标也不同。如303所述，S303和S306的信号强度阈值可以相同也可以不同。在本申请实施例中，可以在每确定一个大于或等于信号强度阈值的目标之后，确定该一个目标的参数，也即是前述S303和S306先后执行；也可以在确定所有目标之后，获取确定的各个目标的参数，也即是前述S303和S306在雷达检测到信号谱达到消除条件后再同时或分别执行。任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化的方法，都应涵盖在本申请的保护范围之内，因此不再赘述。
综上所述，本申实施例提供的目标检测方法，通过重构信号谱中大于或等于信号强度阈值的目标对应的接收信号，并在信号谱上消除重构的接收信号，从而避免消除的接收信号(强目标信号)对确定信号谱中其他目标(弱目标信号)的参数的干扰，从而减少“强掩弱”问题。尤其在信号谱中大于或等于信号强度阈值的目标为信号谱中信号强度最大的目标时，可以避免信号谱中信号强度最大的目标对其他目标的干扰，有效避免“强掩弱”问题，还可以提高该其他目标的检测精度。
在本申请实施例中，如S302所述，信号谱可以有多种获取方式，例如根据DBF算法获取，或根据傅里叶变换算法获取。对于不同的获取方式获取的信号谱，前述S304中信号重构的方式也不同。本申请实施例以信号谱中大于或等于信号强度阈值的目标为信号谱中信号强度最大的目标为例，采用以下几种可选示例进行说明：
在一种可选示例中，在确定信号谱根据DBF算法获取后，重构的接收信号的每个元素的幅度等于信号谱的幅度最大值的预设倍数，重构的接收信号的初始相位等于幅度最大值对应的相位。则，假设前述公式一或公式二中的信号强度最大的目标为第1个目标，该第1个目标的幅度a 1满足：
a 1＝βA；(公式三)
其中，A为信号谱F的幅度最大值，β是一个预设值。
对于DBF算法，β满足：β＝1/L，
Figure PCTCN2020098212-appb-000009
表示信号强度最大的目标在各个接收天线的初始相位，由于DBF算法不会改变输出信号谱的群时延，因而
Figure PCTCN2020098212-appb-000010
等于信号谱F的幅度最大处的相位，即幅度最大值A对应的相位，F(A)表示信号谱F中信号强度最大的目标，则
Figure PCTCN2020098212-appb-000011
f A表示发射信号的频率，t表示时间。
在另一种可选示例中，在确定信号谱根据傅里叶变换算法获取后，重构的接收信号y A等于比例缩放系数α与第一信号谱
Figure PCTCN2020098212-appb-000012
的傅里叶逆变换的乘积，第一信号谱
Figure PCTCN2020098212-appb-000013
与所述信号谱F等长，且第一信号谱
Figure PCTCN2020098212-appb-000014
中除与信号谱F的幅度最大值所在点的位置、幅度和相位均相同之外，其他点的值为0。其中，第一信号谱
Figure PCTCN2020098212-appb-000015
与信号谱F等长指的是第一信号谱
Figure PCTCN2020098212-appb-000016
与信号谱F在傅里叶变换所对应的信号域等长。
其中，傅里叶变换算法可以为FFT算法或DFT算法。相应的，傅里叶变换算法为FFT算法时，傅里叶逆变换为逆离散傅里叶变换(Inverse Fast Fourier Transform，IFFT)；傅里叶变换算法为DFT算法时，傅里叶逆变换为逆离散傅里叶变换(Inverse Discrete Fourier Transform，IDFT)。则本申请实施例分别以以下两方面进行说明：
第一方面，在确定信号谱根据FFT算法获取后，重构的接收信号y A等于比例缩放系数α与第一信号谱
Figure PCTCN2020098212-appb-000017
的IFFT的乘积，第一信号谱
Figure PCTCN2020098212-appb-000018
与信号谱F等长，且第一信号谱
Figure PCTCN2020098212-appb-000019
中除与信号谱F的幅度最大值所在点的位置、幅度和相位均相同之外，其他点的值为0。
例如，重构的接收信号y A表示为：
Figure PCTCN2020098212-appb-000020
其中，α是预设的比例缩放系数，第一信号谱
Figure PCTCN2020098212-appb-000021
与信号谱F等长，且第一信号谱
Figure PCTCN2020098212-appb-000022
中除与信号谱F的幅度最大值所在点的位置、幅度和相位均相同之外，其他点的值为0。
第二方面，在确定信号谱根据DFT算法获取后，重构的接收信号y A等于比例缩放系数α与第一信号谱
Figure PCTCN2020098212-appb-000023
的IDFT的乘积，第一信号谱
Figure PCTCN2020098212-appb-000024
与信号谱F等长，且第一信号谱
Figure PCTCN2020098212-appb-000025
中除与信号谱F的幅度最大值所在点的位置、幅度和相位均相同之外，其他点的值为0。
例如，重构的接收信号y A表示为：
Figure PCTCN2020098212-appb-000026
其中，α是预设的比例缩放系数，第一信号谱
Figure PCTCN2020098212-appb-000027
与信号谱F等长，且第一信号谱
Figure PCTCN2020098212-appb-000028
中除与信号谱F的幅度最大值所在点的位置、幅度和相位均相同之外，其他点的值为0。
进一步的，如前所述，信号谱可以为角度谱、测速谱或测距谱。对于不同的信号谱，目标检测方法的流程也不相同，本申请实施例分别以信号谱为角度谱或测距谱为例，以以下两种可选实施方式分别对目标检测方法进行说明：
在第一种可选实现方式中，信号谱为角度谱，如图10所示，该目标检测方法包括：
S401、通过雷达的发射天线发射信号。
S401可以参考前述S301，本申请实施例对此不做赘述。
S402、根据雷达的接收天线的接收信号，获取角度谱。
S402中获取角度谱的过程可以参考前述S302。
S403、根据角度谱确定大于或等于信号强度阈值的目标的角度。
对于角度谱，目标的参数为角度，当角度谱中大于或等于信号强度阈值的目标为角度谱中信号强度最大的目标时，由于角度谱中的信号强度最大处的幅度也最大，因此，信号强度最大处的角度θ A也等于角度谱中幅度最大值处的角度，可以由角度谱中幅度最大处的角度值表示。雷达在确定了大于或等于信号强度阈值的目标的角度之后，可以输出检测结果来指示目标的角度，例如，该检测结果包括幅度最大处的角度值。
S404、重构信号谱中大于或等于信号强度阈值的目标对应的接收信号。
假设针对雷达的天线阵列确定的同一个目标RD单元对应的接收信号y，执行角度估计算 法，得到的角度谱为复数谱S(θ)＝Τ(y)，其中，Τ(·)表示针对信号y用于求角度谱的运算函数或变换，也即是前述角度估计算法，其可以是DBF算法、DFT或FFT算法等。其中，通过该角度估计算法估算得到的大于或等于信号强度阈值的目标的参数为角度。示例的，假设通过角度估计算法估算得到的信号强度最大的目标(也即是本申请实施例中的重构的接收信号对应的目标)的角度为θ A。则雷达可以通过该角度θ A来重构大于或等于信号强度阈值的目标对应的接收信号。
如前述S303所述，每个接收天线对应一个RD图，L个接收天线的同一个RD单元对应一个角度谱。在本申请实施例中，对于每个角度谱，大于或等于信号强度阈值的目标对应的接收信号的重构方式相同，本申请后续实施例以一个角度谱的接收信号的重构方式为例进行说明，其他角度谱的重构方式参考该一个角度谱中接收信号的重构方式。下面，本申请实施例以以下几种示例为例进行说明：
在第一种可选示例中，在确定角度估计算法为DBF算法后，获取的角度谱F可表示为：S(θ)＝y Ha(θ)。其中，y表示雷达获取的信号。当该信号谱是雷达根据接收天线所接收的初始信号处理得到的，则信号谱F对应的接收信号y为对接收的初始信号经过处理得到的描述该信号谱的接收信号，即未经过信号消除操作的初始接收信号；当该角度谱F是由该初始接收信号经过至少一次信号消除操作得到的中间信号，则y为该中间信号，H表示共轭转置，
Figure PCTCN2020098212-appb-000029
表示角度谱F的相位，如S402，d＝[d 1d 2d 3…d L] T是接收天线的位置矢量。
示例的，雷达根据角度谱中大于或等于信号强度阈值的目标的角度，确定角度谱的其他参数，该其他参数包括：角度谱中目标对应的幅度值和幅度值对应的相位；并根据角度谱的其他参数，重构目标对应的接收信号。
例如，当角度谱中大于或等于信号强度阈值的目标为角度谱中信号强度最大的目标时，对于角度谱中的信号强度最大的目标，采用前述公式三，可以将该目标对应的接收信号重构为：
Figure PCTCN2020098212-appb-000030
其中，d＝[d 1d 2d 3…d L] T是接收天线的位置矢量，λ是信号波长。
其中，θ A为角度谱S(θ)的信号强度最大的目标对应的角度，A为复数谱S(θ)的幅度|S(θ)|的幅度最大值，也即是A＝|S(θ A)|，|*|表示求幅度，
Figure PCTCN2020098212-appb-000031
也即是角度谱F中幅度最大值A对应的相位。雷达可以根据该角度谱F，先确定幅度最大值对应的角度(即信号强度最大的目标对应的角度)θ A，然后根据该幅度最大值对应的角度θ A确定幅度最大值A对应目标的相位。如此，实现根据S(θ A)估计得到其他参数：A和
Figure PCTCN2020098212-appb-000032
进一步的，对于每个接收天线，假设β＝1/L，将重构的接收信号对应的复数信号谱为S(θ A)＝y Ha(θ A)和确定的A和
Figure PCTCN2020098212-appb-000033
代入公式六求出重构的接收信号为：
Figure PCTCN2020098212-appb-000034
其中，L表示接收天线的个数，d＝[d 1d 2d 3…d L] T是L个接收天线的位置形成的矢量，即表示接收天线所组成的天线阵列中各个阵元的位置。
在第二种可选示例中，在确定角度估计算法为FFT算法后，重构的接收信号y A等于比例缩放系数α与第一信号谱
Figure PCTCN2020098212-appb-000035
的IFFT的乘积，第一信号谱
Figure PCTCN2020098212-appb-000036
与信号谱F等长，且第一信号谱
Figure PCTCN2020098212-appb-000037
中除与信号谱F的幅度最大值所在点的位置、幅度和相位均相同之外，其他点的值为0。示例 的，可以确定信号谱F的幅度最大值所在点，将信号谱F该幅度最大值所在点之外的点置0，即得到第一信号谱
Figure PCTCN2020098212-appb-000038
示例的，雷达根据角度谱中大于或等于信号强度阈值的目标的角度，确定角度谱的其他参数，该其他参数包括：角度谱中目标对应的幅度值、该幅度值对应序号和该幅度值对应的相位；并根据角度谱的其他参数，重构目标对应的接收信号。其中，该幅度值对应序号用于指示该幅度值在角度谱中的位置。
例如，当角度谱中大于或等于信号强度阈值的目标为角度谱中信号强度最大的目标时，假设雷达获取的角度谱F可表示为角度的函数：S(θ)，雷达根据|S(θ)|确定幅度最大值A，以及S(θ)的幅度最大值A对应的角度θ A，该角度θ A对应的S(θ)的复数值为S(θ A)，则对S(θ)只保留S(θ A)处的取值，并将S(θ)的其它点的值全部置为0，得到第一信号谱
Figure PCTCN2020098212-appb-000039
该第一信号谱表示为角度θ A的函数：S A(θ A)，针对S A(θ A)执行IFFT算法得到y A。示例的，假设比例缩放系数α＝1，由于S A(θ A)只有一个采样点的值不为0，假设该不为0的采样点在角度谱中的序号为I A，表示该采样点为第I A个采样点，则对于每个接收天线，IFFT结果可以表示为：
Figure PCTCN2020098212-appb-000040
其中，N为角度谱中采样点的总数。
在第三种可选示例中，在确定角度估计算法为DFT算法后，重构的接收信号y A等于比例缩放系数α与第一信号谱
Figure PCTCN2020098212-appb-000041
的IDFT的乘积，第一信号谱
Figure PCTCN2020098212-appb-000042
的定义与前述第二种可选示例相同，IDFT结果的表示方式可以与公式八相同，因此不再赘述。
S405、在角度谱上消除重构的接收信号，得到更新后的角度谱，其中，该更新后的角度谱表示不包含前述目标的角度谱。
其中，S405中过程可以参考前述S305，本申请实施例对此不做赘述。
S406、在更新后的角度谱中确定大于或等于信号强度阈值的目标的角度。
S406可以参考前述S306，本申请实施例对此不做赘述。
S407、重复执行重构角度谱中大于或等于信号强度阈值的目标对应的接收信号，以及在更新后的角度谱中确定大于或等于信号强度阈值的目标的角度的过程。
在确定更新后的角度谱满足消除条件后，重复执行重构角度谱中大于或等于信号强度阈值的目标对应的接收信号，以及在更新后的角度谱中确定大于或等于信号强度阈值的目标的角度的过程，直至更新后的角度谱不满足消除条件。也即是，在确定更新后的角度谱满足消除条件后，重复S404至S405的过程，直至更新后的角度谱不满足消除条件，停止动作。S407可以参考前述S307，本申请实施例对此不做赘述。
S408、根据确定的目标的角度，获取确定的目标的位置信息。
雷达在获取目标的角度后，可以根据获取的角度，确定目标的位置信息。该位置信息可以包括在指定三维坐标系中的位置坐标。例如，雷达可以根据目标与雷达间的距离以及目标与雷达间的角度(即前述通过角度谱获取的角度)，将目标映射到指定三维空间坐标系中，从而形成雷达点云，并根据雷达点云确定目标的准确的位置坐标。
综上所述，本申实施例提供的目标检测方法，通过重构角度谱中大于或等于信号强度阈值的目标对应的接收信号，并在角度谱上消除重构的接收信号，从而避免消除的接收信号对确定角度谱中其他目标的干扰，从而减少“强掩弱”问题，即不仅可使弱目标信号容易被检测出来，而且避免了强目标信号的旁瓣对弱目标的影响，提高了弱目标的检测精度。尤其在 角度谱中大于或等于信号强度阈值的目标为角度谱中信号强度最大的目标时，可以避免角度谱中信号强度最大的目标(强信号目标)对其他目标(弱信号目标)的干扰，有效避免“强掩弱”问题，还可以提高该其他目标的检测精度。
在第二种可选实现方式中，信号谱为测速谱，如图11所示，该目标检测方式包括：
S501、通过雷达的发射天线发射信号。
S301可以参考前述S501，本申请实施例对此不做赘述。
S502、根据雷达的接收天线的接收信号，获取测速谱。
S402中获取测速谱的过程可以参考前述S302。
S503、根据测速谱中确定大于或等于信号强度阈值的目标的速度。
对于测速谱，目标的参数为速度，当测速谱中大于或等于信号强度阈值的目标为测速谱中信号强度最大的目标时，由于测速谱中的信号强度最大处的幅度也最大，因此，信号强度最大处的速度也等于测速谱中幅度最大值处的速度，可以由测速谱中幅度最大处的速度值表示。雷达在确定了大于或等于信号强度阈值的目标的速度之后，可以输出检测结果来指示目标的速度，该例如，检测结果包括幅度最大处的速度值。
S504、重构信号谱中大于或等于信号强度阈值的目标对应的接收信号。
参考S302，测速谱可以采用慢时间维FFT算法获取，则重构的接收信号y A可以采用前述公式四构造。
示例的，对于一个距离为R 0的目标，其径向速度(即朝向雷达移动的速度)为v，FMWC信号包括多个chirp信号，对于一个发送天线发送的信号，雷达进行信号获取和处理后，与该目标对应的慢时间数据序列，也即是测速谱可近似表示为：
Figure PCTCN2020098212-appb-000043
其中，A是目标的幅度，该幅度为测速谱中最大的幅度，m是慢时间维中chirp信号的序号，T是一个chirp信号的持续时长，也称周期，exp()表示以自然常数e为底的指数函数。
以MIMO雷达为例，如果同一个发送天线发送均匀时间间隔的chirp信号序列，对于一个发送天线发送的信号，m是以Y为间隔的等差数列，Y表示发送时间间隔所对应的序列号差值，例如，Y＝4，m是[1,5,9,…]等两两间隔Y的值构成的矢量。如果同一个发送天线发送不均匀时间间隔的chirp信号序列，即MIMO雷达的同一个发送天线的实际发送时序存在变化，例如m取值为[1，3，4，7，8，10…]的矢量。
参考前述公式四，可以将m更新为以1为间隔的等差数列，也即是m是[1,2,3,…]等两两间隔1的值构成的矢量，在保持原y(m)的采样点的值基础上，将y(m)更新为非原m的序号对应的采样点的值为0，更新后的y(m)与原y(m)等长。值得说明的是，当测速谱是采用慢时间维FFT算法获取时，更新后的y(m)与原y(m)等长指的是两者在慢时间维等长。
最终，重构的接收信号y A表示为：
Figure PCTCN2020098212-appb-000044
其中，α是预设的比例缩放系数，第一信号谱
Figure PCTCN2020098212-appb-000045
为更新后的y(m)，例如，α＝1。
S504中的过程可以参考前述S304，本申请实施例对此不做赘述。
S505、在测速谱上消除重构的接收信号，得到更新后的测速谱，其中，该更新后的测速谱表示不包含前述目标的测速谱。
S505中的过程可以参考前述S305，本申请实施例对此不做赘述。
S506、在更新后的角度谱中确定大于或等于信号强度阈值的目标的角度。
S506可以参考前述S306，本申请实施例对此不做赘述。
S507、重复执行重构测速谱中大于或等于信号强度阈值的目标对应的接收信号，以及在更新后的测速谱中确定大于或等于信号强度阈值的目标的角度的过程。
在确定更新后的测速谱满足消除条件后，重复执行重构测速谱中大于或等于信号强度阈值的目标对应的接收信号，以及在更新后的测速谱中确定大于或等于信号强度阈值的目标的角度的过程，直至更新后的测速谱不满足消除条件。也即是，在确定更新后的测速谱满足消除条件后，重复S504至S505的过程，直至更新后的测速谱不满足消除条件，停止动作。S507可以参考前述S307，本申请实施例对此不做赘述。
S508、根据获取的目标的参数，确定目标的速度信息。
雷达在获取目标的速度后，可以根据获取的速度，确定目标的速度信息。该速度信息可以包括目标相对于雷达的速度和/或目标的绝对速度。例如，雷达可以将前述通过测速谱获取的速度确定为目标相对于雷达的速度，进一步可选地，雷达可以基于自身的速度和目标相对于雷达的速度，确定目标的绝对速度。
综上所述，本申实施例提供的目标检测方法，通过重构测速谱中大于或等于信号强度阈值的目标对应的接收信号，并在测速谱上消除重构的接收信号，从而避免消除的接收信号对确定测速谱中其他目标的参数的干扰，从而减少“强掩弱”问题。尤其在测速谱中大于或等于信号强度阈值的目标为测速谱中信号强度最大的目标时，可以避免测速谱中信号强度最大的目标(强信号目标)对其他目标(弱信号目标)的干扰，有效避免“强掩弱”问题，还可以提高该其他目标的检测精度。
为了便于读者理解，本申请实施例下面对一种示意性的目标检测方法的实际实现过程进行说明，假设信号谱为经过FFT算法得到的AOA谱，信号谱中大于或等于信号强度阈值的目标为信号谱中信号强度最大的目标，该目标检测方法包括：
C1、雷达通过雷达的发射天线发射信号后，根据雷达的接收天线获取接收信号y；
C2、根据接收信号y，经过FFT算法得到AOA谱；
C3、根据AOA谱确定信号强度最大的目标的角度；
C4、根据信号强度最大的目标的角度，获取该AOA谱的最大幅度A，并记录该最大幅度A在AOA谱中对应的序号；
C5、根据最大幅度A和记录的序号，重构信号强度最大的目标的接收信号y A；
C6、更新AOA谱对应的接收信号y，使得更新后的接收信号y＝y-y A；
C7、根据更新后的接收信号y获取更新后的AOA谱；
C8、根据更新后的AOA谱确定信号强度最大的目标的角度；
C9、检测更新后的AOA谱是否达到消除条件；
C10、当更新后的AOA谱未达到消除条件，停止动作；当更新后的AOA谱达到消除条件，重复执行C4至C10的过程直至更新后的AOA谱未达到消除条件，停止动作。
值得说明的是，前述流程C3和流程C8所述的目标是不同的目标，在流程C3之前，雷达还可以检测AOA谱是否达到消除条件；当AOA谱未达到消除条件，说明AOA谱中不存 在目标，停止动作，即停止执行流程C3；当AOA谱达到消除条件，执行流程C3。
前述重复执行C4至C10的过程是接收信号y的迭代过程，采用迭代的方式，通过信号消除操作(参考C6和C7)消除测速谱中信号强度最大的目标对应的接收信号，从而避免了消除的信号(强目标信号)对确定指示另一目标(弱目标信号)的信号干扰，从而减少“强掩弱”问题，并且提高了弱目标信号的检测精度。
需要说明的是，本申请前述实施例主要以信号谱中大于或等于信号强度阈值的目标为信号谱中信号强度最大的目标为例对目标检测方法进行说明，实际实现时，在确定信号谱中大于或等于信号强度阈值的目标不仅包括信号谱中信号强度最大的目标，还包括其他目标的情况下，其他目标的处理方式参考该信号强度最大的目标的处理方式，例如目标对应的接收信号的重构方式以及从信号谱对应的接收信号中消除该目标对应的接收信号的方式均可以参考该信号强度最大的目标的对应过程，本申请实施例对此不再赘述。
图12是一示意性的雷达所在的目标识别场景的示意图，图13是本申请实施例提供的一种AOA谱对比示意图。其中，图13中曲线1为采用传统的目标识别方法对图12所示场景进行识别所获取的AOA谱，图13中曲线2为采用本申请实施例提供的目标识别方法对图12所示场景进行2次目标识别流程后所获取的AOA谱(也即是进行过两个AOA谱的更新)示意图。假设图12中的3个相机按照从右到左的顺序分别为目标1、目标2和目标3。采用传统的目标识别方法对图12进行目标检测，由于AOA谱上存在多个目标，且多个目标之间的幅度差别可能高达20dB以上，目标3的主瓣被两个幅度较大的目标：目标1和目标2的旁瓣所影响，导致目标3对应的信号被“掩盖”，出现了“强掩弱”的问题。而本申请实施例，经过2次目标识别流程，目标1和目标2均有超过20dB的衰减，而目标3的峰值衰减较小，且目标1和目标2的信号旁瓣有明显的衰减，减少了目标1和目标2信号旁瓣叠加的影响后，使得目标3的检测更为容易和准确。因此，本申请实施例提供的目标检测方法能够实现更为准确的目标检测。
本申请实施例一种目标检测装置60，如图14所示，应用于雷达，该装置包括：
第一获取模块601，用于根据该雷达的接收天线的接收信号，获取信号谱；
重构模块602，用于重构该信号谱中大于或等于信号强度阈值的目标对应的接收信号；
消除模块603，用于在该信号谱上消除重构的接收信号，得到更新后的信号谱，其中，该更新后的信号谱表示不包含该目标的信号谱；
确定模块604，用于在该更新后的信号谱中确定大于或等于信号强度阈值的目标的参数；
第二获取模块605，用于根据确定的目标的参数，获取确定的目标的位置信息或速度信息中的至少一种。
综上所述，本申实施例提供的目标检测装置，通过重构模块重构信号谱中大于或等于信号强度阈值的目标对应的接收信号，并由消除模块在信号谱上消除重构的接收信号，从而避免消除的接收信号(强目标信号)对确定信号谱中其他目标(弱目标信号)的参数的干扰，从而减少“强掩弱”问题。尤其在信号谱中大于或等于信号强度阈值的目标为信号谱中信号强度最大的目标时，可以避免信号谱中信号强度最大的目标对其他目标的干扰，有效避免“强掩弱”问题，还可以提高该其他目标的检测精度。
可选地，该消除模块603，用于：在确定该信号谱满足消除条件后，在该信号谱上消除 重构的接收信号，得到更新后的信号谱，该消除条件包括以下至少一种：该信号谱中的大于或等于信号强度阈值的目标的幅度小于幅度阈值；该信号谱中的大于或等于信号强度阈值的目标的峰均比小于峰均比阈值；以及，在获取信号谱后执行该消除重构的接收信号的次数小于次数阈值。
可选地，如图15所示，该装置60还包括：
处理模块606，用于在该更新后的信号谱中确定大于或等于信号强度阈值的目标的参数后，在确定该更新后的信号谱满足消除条件后，重复执行该重构该信号谱中大于或等于信号强度阈值的目标对应的接收信号，以及在该更新后的信号谱中确定大于或等于信号强度阈值的目标的参数，直至更新后的信号谱不满足该消除条件。
可选地，该消除模块603，用于：
将该信号谱对应的接收信号与该重构的接收信号之差，确定为更新后的信号谱对应信号；根据该更新后的信号谱对应信号确定该更新后的信号谱。
可选地，该重构模块602，用于：
根据该信号谱中大于或等于信号强度阈值的目标的参数，确定该信号谱的其他参数，该其他参数包括：该信号谱中该目标对应的幅度值、该幅度值对应的序号和该幅度值对应的相位中的一种或多种；
根据该信号谱的其他参数，重构该目标对应的接收信号。
可选地，信号谱中大于或等于信号强度阈值的目标为该信号谱中信号强度最大的目标。
可选地，在确定该信号谱根据数字波束赋形DBF算法获取后，重构的接收信号的每个元素的幅度等于该信号谱的幅度最大值的预设倍数，重构的接收信号的初始相位等于该幅度最大值对应的相位。
可选地，该预设倍数为该雷达的接收天线的个数的倒数。
可选地，在确定该信号谱根据傅里叶变换算法获取后，重构的接收信号等于比例缩放系数与第一信号谱的傅里叶逆变换的乘积，第一信号谱与该信号谱等长，且该第一信号谱中除与该信号谱的幅度最大值所在点的位置、幅度和相位均相同之外，其他点的值为0。
可选地，该信号谱为角度谱，该目标的参数包括角度；
或者，该信号谱为测速谱，该目标的参数包括速度；
或者，该信号谱为测距谱，该目标的参数包括距离。
可选地，图16是本申请实施例提供的计算机设备700的一种可能的基本硬件架构。该计算机设备700可以应用于雷达中。参见图16，计算机设备700包括处理器701、存储器702、通信接口703和总线704。
计算机设备700中，处理器701的数量可以是一个或多个，图16仅示意了其中一个处理器701。可选地，处理器701，可以是中央处理器(central processing unit，CPU)。如果计算机设备700具有多个处理器701，多个处理器701的类型可以不同，或者可以相同。可选地，计算机设备700的多个处理器701还可以集成为多核处理器。
存储器702存储计算机指令和数据；存储器702可以存储实现本申请提供的目标识别方法所需的计算机指令和数据，例如，存储器702存储用于实现目标识别方法的步骤的指令。存储器702可以是以下存储介质的任一种或任一种组合：非易失性存储器(例如只读存储器(ROM)、固态硬盘(SSD)、硬盘(HDD)、光盘)，易失性存储器。
通信接口703可以是以下器件的任一种或任一种组合：网络接口(例如以太网接口)、无线网卡等具有网络接入功能的器件。
通信接口703用于计算机设备700与其它计算机设备或者终端进行数据通信。
总线704可以将处理器701与存储器702和通信接口703连接。这样，通过总线704,处理器701可以访问存储器702，还可以利用通信接口703与其它计算机设备或者终端进行数据交互。
在本申请中，计算机设备700执行存储器702中的计算机指令，使得计算机设备700实现本申请提供的目标检测方法。
本申请实施例提供一种雷达80，该雷达可以应用于国防、无人驾驶以及地理测绘等领域，如图17所示，该雷达80包括：
发射天线801、接收天线802、处理器803和存储器804，所述存储器804中存储指令，所述处理器803执行所述指令来本申请实施例提供的所述的目标检测方法。该存储器和处理器的结构和功能可以分别参考前述图16对应的处理器701和存储器702的结构和功能。
在示例性实施例中，还提供一种计算机可读存储介质，所述计算机可读存储介质内存储有计算机程序，所述计算机程序被处理器执行时本申请实施例提供的目标检测方法。例如，该存储介质为包括指令的存储器，上述指令可由计算机设备或雷达的处理器执行以完成本申请各个实施例所示的目标识别方法。例如，计算机可读存储介质可以是ROM、随机存取存储器(RAM)、CD-ROM、磁带、软盘和光数据存储设备等。
本申请实施例中提供的目标检测方法可以应用一种车辆90，如图18所示，包括：车身901，以及本申请实施例提供的雷达902，该雷达902可以为车辆的前置雷达或后置雷达。该雷达可以为前述实施例中的雷达80。
示例地，该车辆还可以包括：整车控制器、前桥、前悬架、前车轮、变速器、传动轴、消音器、后悬架、钢板弹簧、减震器、后轮、制动器、后桥、座椅、方向盘、转向器和散热器中的一种或多种，本申请对此不做限定。
在本申请中，术语“第一”、“第二”和“第三”仅用于描述目的，而不能理解为指示或暗示相对重要性。术语“至少一个”表示1个或多个，术语“多个”指两个或两个以上，除非另有明确的限定。A参考B，指的是A与B相同或者A为B的简单变形。
需要说明的是：上述实施例提供的目标检测装置在执行该目标检测方法时，仅以上述各功能模块的划分进行举例说明，实际应用中，可以根据需要而将上述功能分配由不同的功能模块完成，即将设备的内部结构划分成不同的功能模块，以完成以上描述的全部或者部分功能。另外，上述实施例提供的目标识别装置与目标识别方法实施例属于同一构思，其具体实现过程详见方法实施例，这里不再赘述。
本领域普通技术人员可以理解实现上述实施例的全部或部分步骤可以通过硬件来完成，也可以通过程序来指令相关的硬件完成，所述的程序可以存储于一种计算机可读存储介质中，上述提到的存储介质可以是只读存储器，磁盘或光盘等。
以上所述仅为本申请的示例性实施例，并不用以限制本申请，凡在本申请的构思和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。

Claims (23)

  1. 一种目标检测方法，应用于雷达，其特征在于，所述方法包括：
    根据所述雷达的接收天线的接收信号，获取信号谱；
    重构所述信号谱中大于或等于信号强度阈值的目标对应的接收信号；
    在所述信号谱上消除重构的接收信号，得到更新后的信号谱，其中，所述更新后的信号谱表示不包含所述目标的信号谱；
    在所述更新后的信号谱中确定大于或等于信号强度阈值的目标的参数；
    根据确定的目标的参数，获取确定的目标的位置信息或速度信息中的至少一种。
  2. 根据权利要求1所述的方法，其特征在于，在所述信号谱上消除重构的接收信号，得到更新后的信号谱，包括：
    在确定所述信号谱满足消除条件后，在所述信号谱上消除重构的接收信号，得到更新后的信号谱，所述消除条件包括以下至少一种：
    所述信号谱中的大于或等于信号强度阈值的目标的幅度小于幅度阈值；
    所述信号谱中的大于或等于信号强度阈值的目标的峰均比小于峰均比阈值；
    以及，在获取信号谱后执行所述消除重构的接收信号的次数小于次数阈值。
  3. 根据权利要求2所述的方法，其特征在于，在所述更新后的信号谱中确定大于或等于信号强度阈值的目标的参数后，所述方法还包括：
    在确定所述更新后的信号谱满足消除条件后，重复执行所述重构所述信号谱中大于或等于信号强度阈值的目标对应的接收信号，以及在所述更新后的信号谱中确定大于或等于信号强度阈值的目标的参数，直至更新后的信号谱不满足所述消除条件。
  4. 根据权利要求2所述的方法，其特征在于，所述在所述信号谱上消除重构的接收信号，得到更新后的信号谱，包括：
    将所述信号谱对应的接收信号与所述重构的接收信号之差，确定为更新后的信号谱对应信号；
    根据所述更新后的信号谱对应信号确定所述更新后的信号谱。
  5. 根据权利要求1至4任一所述的方法，其特征在于，所述重构所述信号谱中大于或等于信号强度阈值的目标对应的接收信号，包括：
    根据所述信号谱中大于或等于信号强度阈值的目标的参数，确定所述信号谱的其他参数，所述其他参数包括：所述信号谱中所述目标对应的幅度值、所述幅度值对应的序号和所述幅度值对应的相位中的一种或多种；
    根据所述信号谱的其他参数，重构所述目标对应的接收信号。
  6. 根据权利要求5所述的方法，其特征在于，信号谱中大于或等于信号强度阈值的目标为所述信号谱中信号强度最大的目标。
  7. 根据权利要求6所述的方法，其特征在于，在确定所述信号谱根据数字波束赋形DBF算法获取后，重构的接收信号的每个元素的幅度等于所述信号谱的幅度最大值的预设倍数，重构的接收信号的初始相位等于所述幅度最大值对应的相位。
  8. 根据权利要求7所述的方法，其特征在于，所述预设倍数为所述雷达的接收天线的个 数的倒数。
  9. 根据权利要求6所述的方法，其特征在于，在确定所述信号谱根据傅里叶变换算法获取后，重构的接收信号等于比例缩放系数与第一信号谱的傅里叶逆变换的乘积，第一信号谱与所述信号谱等长，且所述第一信号谱中除与所述信号谱的幅度最大值所在点的位置、幅度和相位均相同之外，其他点的值为0。
  10. 根据权利要求1至9任一所述的方法，其特征在于，所述信号谱为角度谱，所述目标的参数包括角度；
    或者，所述信号谱为测速谱，所述目标的参数包括速度；
    或者，所述信号谱为测距谱，所述目标的参数包括距离。
  11. 一种目标检测装置，应用于雷达，其特征在于，所述装置包括：
    第一获取模块，用于根据所述雷达的接收天线的接收信号，获取信号谱；
    重构模块，用于重构所述信号谱中大于或等于信号强度阈值的目标对应的接收信号；
    消除模块，用于在所述信号谱上消除重构的接收信号，得到更新后的信号谱，其中，所述更新后的信号谱表示不包含所述目标的信号谱；
    确定模块，用于在所述更新后的信号谱中确定大于或等于信号强度阈值的目标的参数；
    第二获取模块，用于根据确定的目标的参数，获取确定的目标的位置信息或速度信息中的至少一种。
  12. 根据权利要求11所述的装置，其特征在于，所述消除模块，用于：
    在确定所述信号谱满足消除条件后，在所述信号谱上消除重构的接收信号，得到更新后的信号谱，所述消除条件包括以下至少一种：
    所述信号谱中的大于或等于信号强度阈值的目标的幅度小于幅度阈值；
    所述信号谱中的大于或等于信号强度阈值的目标的峰均比小于峰均比阈值；
    以及，在获取信号谱后执行所述消除重构的接收信号的次数小于次数阈值。
  13. 根据权利要求12所述的装置，其特征在于，所述装置还包括：
    处理模块，用于在所述更新后的信号谱中确定大于或等于信号强度阈值的目标的参数后，在确定所述更新后的信号谱满足消除条件后，重复执行所述重构所述信号谱中大于或等于信号强度阈值的目标对应的接收信号，以及在所述更新后的信号谱中确定大于或等于信号强度阈值的目标的参数，直至更新后的信号谱不满足所述消除条件。
  14. 根据权利要求12所述的装置，其特征在于，所述消除模块，用于：
    将所述信号谱对应的接收信号与所述重构的接收信号之差，确定为更新后的信号谱对应信号；
    根据所述更新后的信号谱对应信号确定所述更新后的信号谱。
  15. 根据权利要求11至14任一所述的装置，其特征在于，所述重构模块，用于：
    根据所述信号谱中大于或等于信号强度阈值的目标的参数，确定所述信号谱的其他参数，所述其他参数包括：所述信号谱中所述目标对应的幅度值、所述幅度值对应的序号和所述幅度值对应的相位中的一种或多种；
    根据所述信号谱的其他参数，重构所述目标对应的接收信号。
  16. 根据权利要求15所述的装置，其特征在于，信号谱中大于或等于信号强度阈值的目标为所述信号谱中信号强度最大的目标。
  17. 根据权利要求16所述的装置，其特征在于，在确定所述信号谱根据数字波束赋形DBF算法获取后，重构的接收信号的每个元素的幅度等于所述信号谱的幅度最大值的预设倍数，重构的接收信号的初始相位等于所述幅度最大值对应的相位。
  18. 根据权利要求17所述的装置，其特征在于，所述预设倍数为所述雷达的接收天线的个数的倒数。
  19. 根据权利要求16所述的装置，其特征在于，在确定所述信号谱根据傅里叶变换算法获取后，重构的接收信号等于比例缩放系数与第一信号谱的傅里叶逆变换的乘积，第一信号谱与所述信号谱等长，且所述第一信号谱中除与所述信号谱的幅度最大值所在点的位置、幅度和相位均相同之外，其他点的值为0。
  20. 根据权利要求11至19任一所述的装置，其特征在于，所述信号谱为角度谱，所述目标的参数包括角度；
    或者，所述信号谱为测速谱，所述目标的参数包括速度；
    或者，所述信号谱为测距谱，所述目标的参数包括距离。
  21. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质内存储有计算机程序，所述计算机程序被处理器执行时实现权利要求1至10任一项所述的目标检测方法。
  22. 一种雷达，其特征在于，该雷达包括：
    发射天线、接收天线、处理器和存储器，所述存储器中存储指令，所述处理器执行所述指令来实现如权利要求1至10任一项所述的目标检测方法。
  23. 一种车辆，其特征在于，包括：车身，以及如权利要求22所述的雷达。
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