MIMO sensor, angle of arrival approximation judgment method, and target information matching method

Abstract

The application discloses a MIMO sensor and an arrival angle approximation degree judgment method and a target information matching method. The arrival angle approximation degree judgment method comprises the following steps: obtaining a receiving vector of a first target and a receiving vector of a second target respectively according to a processing result of a multi-channel echo signal; calculating a correlation coefficient of the receiving vector of the first target and the receiving vector of the second target; and judging an arrival angle approximation degree of the first target and the second target according to the correlation coefficient. The arrival angle approximation degree judgment method can improve the real-time performance of multi-channel echo signal processing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of signal processing, and more particularly, to a MIMO sensor and a method for judging the approximation of the angle of arrival and a method for matching target information. BACKGROUND

[0002] MIMO (Multiple Input Multiple Output) sensors working based on radar principle have a wide application prospect in the field of automatic driving, for example, installing MIMO sensors on vehicles for detecting target information of actual objects such as obstacles in the environment. In the MIMO sensor, a transmitting antenna transmits a series of continuous pulse signals, and a receiving antenna receives the echoes of the pulse signals, and after processing, the detected target information is output. This process is generally referred to as a frame in time. The radar detects the moving or stationary objects around in real time by receiving the echo signals of continuous frames and performing corresponding signal processing. The target information obtained by the MIMO sensor includes the distance, radial velocity, azimuth, height, etc. of the actual object relative to the transmitting antenna.

[0003] In the processing of multi-channel echo signals, it is necessary to judge whether two target information in the same frame or adjacent frames correspond to the same actual object for object differentiation, or whether two target information in adjacent frames correspond to the same actual object for object tracking. This process is called a target information matching method. Target information matching can be achieved by measuring the proximity of the information parameters (such as distance, velocity, direction of arrival (DOA)) of two targets. When the information parameters of two targets are very close, i.e. matching is successful, it is considered that the target information corresponds to the same actual object. In addition, in some other applications of radar, such as setting different pulse repetition frequencies (PRF) for adjacent frames, and then matching the target information, the velocity measurement of high-speed targets can be achieved.

[0004] The above existing target information matching method includes: performing intra-frame correlation calculation on the multi-channel echo signals to obtain the information parameters of the target, and then performing information parameter comparison within the same frame or between adjacent frames to judge whether two targets correspond to the same actual object. For example, based on the comparison result of the angles of arrival of two targets, the approximation of the angle of arrival can be judged and the target information can be matched. However, in order to obtain the angle of arrival of the target, the signal processing of the multi-channel echo signals needs to perform multiple digital beam forming (DBF) operations related to the scanning angle. Therefore, the signal processing process of the existing target information matching method is relatively complex, and the correlation calculation is time-consuming, which degrades the real-time performance of the multi-channel echo signal processing. SUMMARY

[0005] In view of the above-mentioned problems existing in the prior art, the present application aims to provide a MIMO sensor and an angle of arrival approximation judgment method and a target information matching method, in which correlation calculation is performed on the receiving vectors of two targets to determine whether the two targets correspond to the same actual object, thereby improving the real-time performance of multi-channel echo signal processing.

[0006] The present application provides a target-to-target angle of arrival approximation judgment method, which can be applied to a MIMO sensor, and the method comprises:

[0007] According to the processing result of the multi-channel echo signal, receiving vectors of a first target and a second target are obtained respectively;

[0008] Correlation coefficients of the receiving vectors of the first target and the second target are calculated; and

[0009] According to the correlation coefficients, the approximation degree of the angles of arrival of the first target and the second target is determined.

[0010] In the above-mentioned method, the approximation degree of the angles of arrival between the first target and the second target can be determined without obtaining the numerical values of the angles of arrival of the first target and the second target by using the correlation coefficients between the receiving vectors of the targets, thereby improving the real-time performance of multi-channel (i.e., at least two transceiving channels) echo signal processing.

[0011] Optionally, the receiving vectors can include distance information and speed information, such as distance vectors and speed vectors, i.e., the correlation coefficients can be obtained based on the distance and speed information without the angle of arrival information.

[0012] Optionally, the calculation of the correlation coefficients of the receiving vectors of the first target and the second target can comprise:

[0013] The receiving vectors of the first target and the second target can be subjected to conjugate correlation processing or the like to obtain the correlation coefficients.

[0014] The value of the correlation coefficients is positively correlated with the approximation degree of the angles of arrival between the first target and the second target.

[0015] Optionally, the first target and the second target are different targets detected in the same frame of multi-channel echo signal, and are used to determine the approximation degree of the angles of arrival between two actual objects (targets) at the same time (i.e., within one frame period).

[0016] Optionally, the first target and the second target are the same or different targets detected in consecutive frames of multi-channel echo signal.

[0017] The application further provides a target information matching method, which can be applied to a MIMO sensor, and the method can comprise the following steps:

[0018] receiving a multi-channel echo signal of continuous frames;

[0019] obtaining a receiving vector of a first target and a receiving vector of a second target in adjacent frames of the continuous frames respectively according to a processing result of the multi-channel echo signal;

[0020] calculating a correlation coefficient of the receiving vector of the first target and the receiving vector of the second target; and

[0021] judging whether the first target and the second target match a same actual object according to the correlation coefficient.

[0022] The target information matching method can quickly judge whether two targets in adjacent frames match a same actual object (target) through calculation of the receiving vector, and thus the quick matching of target information output by two frames is realized.

[0023] Optionally, the receiving vector can comprise distance information and speed information, that is, the quick matching of the angle of arrival of target information output by two frames is realized based on the receiving vector comprising distance and speed information, so that the step of calculating the angle of arrival of each target is not needed, and thus the failure rate is greatly reduced and the signal data processing resource is saved.

[0024] Optionally, the calculation of the correlation coefficient of the receiving vector of the first target and the receiving vector of the second target comprises:

[0025] performing processing such as conjugate correlation on the receiving vector of the first target and the receiving vector of the second target to obtain the correlation coefficient;

[0026] wherein the value of the correlation coefficient is positively correlated with the approximate degree of the angle of arrival between the first target and the second target.

[0027] Optionally, the adjacent frames comprise a first frame and a second frame, and the first target and the second target are targets detected in the first frame and the second frame respectively.

[0028] Optionally, the step of obtaining the receiving vector of the first target and the receiving vector of the second target in the adjacent frames of the continuous frames comprises:

[0029] performing signal processing on the multi-channel echo signal of the adjacent frames respectively to obtain multi-channel range-Doppler two-dimensional data of the first frame;

[0030] detecting the first target by searching for a peak value in the multi-channel range-Doppler two-dimensional data of the first frame; and

[0031] The second target is detected by searching for a peak in the multi-channel range-Doppler two-dimensional data of the second frame.

[0032] Optionally, the first target corresponds to a first group of range-Doppler cells in the multi-channel range-Doppler two-dimensional data of the first frame, and the second target corresponds to a second group of range-Doppler cells in the multi-channel range-Doppler two-dimensional data of the second frame.

[0033] Each of the first group of range-Doppler cells and the second group of range-Doppler cells includes a coordinate parameter in the corresponding range-Doppler two-dimensional data, which includes range information and velocity information.

[0034] Optionally, a receiving vector of the first target includes a first group of elements, each of which represents a complex value of the first group of range-Doppler cells at a corresponding coordinate on a range-Doppler two-dimensional complex plane, and a receiving vector of the second target includes a second group of elements, each of which represents a complex value of the second group of range-Doppler cells at a corresponding coordinate on the range-Doppler two-dimensional complex plane.

[0035] Optionally, a correlation coefficient of the receiving vectors of the first target and the second target can be calculated by using the following formula:

[0036] corr_coe = RV_VEC_A * (RV_VEC_B)H / (||RV_VEC_A|| * ||RV_VEC_B||)

[0037] |RV_VEC_A*(RV_VEC_B) H | / (|RV_VEC_A|*|RV_VEC_B|)

[0038] wherein RV_VEC_A represents a receiving vector of the first target TA, RV_VEC_B represents a receiving vector of the second target TB, H represents conjugate and transpose, / represents division, and || represents vector norm.

[0039] Optionally, if the correlation coefficient is greater than a predetermined value, it is determined that the first target and the second target match the same actual object.

[0040] Optionally, if the correlation coefficient is less than or equal to a predetermined value, it is determined that the first target and the second target do not match the same actual object, and the angle of arrival approximation determination method traverses a plurality of targets detected in the continuous frames to obtain the first target and the second target that match the same actual object.

[0041] The present application also provides a MIMO sensor, which can include:

[0042] a plurality of transceiving channels for receiving a multi-channel echo signal; and

[0043] a signal processing unit for performing signal processing on the multi-channel echo signal, and obtaining a receiving vector of a first target and a receiving vector of a second target respectively according to a processing result of the signal processing,

[0044] wherein the signal processing unit further calculates a correlation coefficient of the receiving vector of the first target and the receiving vector of the second target, and judges an approximation degree of an angle of arrival of the first target and the second target according to the correlation coefficient.

[0045] Optionally, the receiving vector can include distance information and velocity information.

[0046] Optionally, the calculating the correlation coefficient of the receiving vector of the first target and the receiving vector of the second target comprises:

[0047] performing a conjugate correlation processing on the receiving vector of the first target and the receiving vector of the second target to obtain the correlation coefficient;

[0048] wherein a value of the correlation coefficient is positively correlated with an approximation degree of an angle of arrival between the first target and the second target.

[0049] Optionally, the plurality of transceiving channels comprises:

[0050] a plurality of antennas, the plurality of antennas comprising a combination of at least one transmitting antenna and a plurality of receiving antennas, or a combination of a plurality of transmitting antennas and at least one receiving antenna;

[0051] a transmitting unit connected with a transmitting antenna in the plurality of antennas to provide at least one transmitting channel;

[0052] a receiving unit connected with a receiving antenna in the plurality of antennas to provide at least one receiving channel,

[0053] wherein a total number of the at least one transmitting channel and the at least one receiving channel is greater than or equal to 3.

[0054] Optionally, the MIMO sensor further comprises:

[0055] a control unit connected with the transmitting unit and the receiving unit, the control unit controlling the transmitting unit to generate a transmitting signal, thereby being converted into a radar beam via a transmitting antenna in the plurality of antennas, and controlling the receiving unit to obtain a multi-channel echo signal via a receiving antenna in the plurality of antennas.

[0056] Optionally, the first target and the second target are the same or different targets detected in continuous frame multi-channel echo signals.

[0057] Optionally, the signal processing unit obtains a receiving vector of the first target and a receiving vector of the second target in adjacent frames of the continuous frames respectively.

[0058] Optionally, the signal processing unit judges whether the first target and the second target match a same actual object according to the correlation coefficient.

[0059] According to the target information matching method and the target information matching method, the correlation coefficient is directly calculated according to the receiving vectors of the two targets, and the matching degree of the angles of arrival of the two targets is evaluated according to the value of the correlation coefficient. The value of the correlation coefficient is positively correlated with the approximation degree of the angles of arrival between the first target and the second target, that is, the greater the correlation coefficient, the higher the matching degree of the angles of arrival. The target information matching method and the target information matching method do not need to actually calculate the angles of arrival of the targets, so the complex calculation process of digital beam synthesis can be simplified. In particular, since the vector inner product operation between the receiving vector and the steering vector is not performed, the multiple digital beam forming (DBF) operations related to the scanning angle of the radar beam can be significantly reduced. Assuming that the scanning angle range of the digital beam forming is-60 degrees to 60 degrees, with an interval of 1 degree, the calculation of the angle of arrival of each target needs to be performed 120 times of correlation calculation, and the comparison of the angles of arrival of the two targets needs to be performed 240 times of correlation calculation by using the existing target information matching method. The correlation coefficient calculation of the receiving vectors of the two targets only needs to be performed once by using the target information matching method.

[0060] Therefore, the signal processing process of the target information matching method and the target information matching method according to the embodiments of the present application simplifies the correlation calculation complexity, significantly shortens the time consumption, and can significantly improve the real-time performance of the multi-channel echo signal processing. BRIEF DESCRIPTION OF DRAWINGS

[0061] The above and other objects, features and advantages of the present application will become more apparent from the following description when taken in conjunction with the accompanying drawings, in which:

[0062] Figure 1 A structure schematic diagram of a MIMO sensor is shown.

[0063] Figure 2 A flowchart according to a conventional target information matching method is shown.

[0064] Figure 3 A flowchart according to the target information matching method according to the embodiments of the present application is shown.

[0065] Figure 4 A flowchart according to the target information matching method according to the embodiments of the present application is shown. Figure 3Fig. 1 is a schematic diagram of a signal processing procedure for obtaining distance-Doppler two-dimensional data in the target information matching method shown.

[0066] Figure 5 Fig. 2 shows a schematic diagram of a distance-Doppler unit coordinate in the target information matching method shown. Figure 3 DETAILED DESCRIPTION

[0067] The present application will be described in more detail by referring to the attached drawings. Like elements are denoted by like reference numerals throughout the various figures. Individual sections of the drawings have not been drawn to scale for the sake of clarity. Further, certain known elements can not be shown in the figures.

[0068] Figure 1 Fig. 1 shows a schematic diagram of a structure of a MIMO sensor. The MIMO sensor 100 is mounted on a vehicle, for example, for detecting target information of actual objects such as obstacles in the environment.

[0069] The MIMO sensor 100 includes a control unit 101, a transmitting unit 102, a receiving unit 103, an interface unit 104, an oscillator 105, a signal processing unit 106, a transmitting antenna Tx, and receiving antennas Rx1 to Rx4. The transmitting unit 102 is connected to the transmitting antenna Tx for providing a transmitting signal. The receiving unit 103 is connected to the receiving antennas Rx1 to Rx4 for obtaining a return signal.

[0070] The oscillator 105 is used to generate a radio frequency signal. The oscillator 105 is a phase-locked loop including a phase detector, a low-pass filter, and a voltage-controlled oscillator, for example. The phase detector detects a phase difference between an input signal and an output signal to generate a control voltage. The voltage-controlled oscillator adjusts a frequency according to the control voltage, so that the phase-locked loop can provide a radio frequency signal identical to the input signal and the output signal. The oscillator 105 provides the radio frequency signal to the transmitting unit 102 and the receiving unit 103.

[0071] The transmitting unit 102 is connected to the transmitting antenna Tx to form a transmitting channel. The transmitting unit 102 performs power amplification on the radio frequency signal provided by the oscillator 105 to obtain a transmitting signal, and provides the transmitting signal to the transmitting antenna Tx. The transmitting antenna Tx is used to perform a conversion between a waveguide field and a spatial radiation field, and converts the transmitting signal into a radar beam radiated into the surrounding environment.

[0072] ​The receiving unit 103 is connected with a plurality of receiving antennas Rx1 to Rx4 to form a plurality of receiving channels. In the case that there are obstacles in the surrounding environment, the receiving antennas Rx1 to Rx4 can receive echoes of the radar beam, and the receiving antennas Rx1 to Rx4 are used to convert the spatial radiation field and the waveguide field to obtain echo signals of the echoes. The receiving unit 103 mixes the echo signals of the plurality of receiving channels with the radio frequency signals provided by the oscillator 105 to generate primary analog signals, and converts the primary analog signals into analog input signals.

[0073] The control unit 101 is connected with the transmitting unit 102 and the receiving unit 103. The control unit 101 controls the transmitting unit 102 to generate a transmitting signal, which is converted into a radar beam via the transmitting antenna Tx, and controls the receiving unit 103 to obtain multi-channel echo signals via the receiving antennas Rx1 to Rx4.

[0074] The interface unit 104 is connected with the control unit 101 to provide a communication interface between the control unit 101 and an external device. In the case of automatic driving, the external device is for example a vehicle controller. The control unit 101 sends result data to the external device via the interface unit 104. Further, the external device can control the vehicle operation according to the result data of the MIMO sensor, for example, to realize the function of active obstacle avoidance and the like.

[0075] The signal processing unit 106 samples the analog input signals to obtain digital signals, and performs a first digital signal processing process on the digital signals to obtain intermediate data. Specifically, the control unit 101 includes an analog-to-digital converter and a radar processor. The analog-to-digital converter is used to sample the analog input signals according to a sampling clock signal to obtain corresponding digital signals; the radar processor includes a plurality of processing units and a storage unit for storing intermediate data and / or result data. The plurality of processing units of the radar processor performs at least part of the following data processing processes: Fourier transform, target detection, angle detection and point cloud imaging, wherein the Fourier transform can include one-dimensional FFT transform (1D-FFT) and two-dimensional FFT transform (2D-FFT). The signal processing unit 106 performs signal processing and data processing on the echo signals, and can obtain result data such as distance, speed and direction of arrival (DOA) of the target.

[0076] The signal processing unit 106 obtains the target's result data based on the echo signal through signal processing. Range and velocity information can generally be directly extracted from the range-Doppler two-dimensional data after processing the multi-channel echo signal. However, obtaining the angle of arrival information typically requires a more complex processing procedure, such as digital beamforming (DBF). Measuring the target's angle of arrival using digital beamforming requires multiple transmit and receive channels, such as... Figure 1 As shown, signal processing of the echo signal from each receiving channel yields range-Doppler two-dimensional data. Each target corresponds to a range-Doppler cell. The range-Doppler cell data corresponding to the same target from all receiving channels are combined into a receiving vector, and correlation calculation is performed with a set of steering vectors, i.e., vector inner product operation, to obtain the correlation spectrum. This process is digital beamforming. The angle corresponding to the peak of the correlation spectrum is the azimuth angle of the target relative to the radar, i.e., the angle of arrival.

[0077] exist Figure 1 The diagram illustrates a MIMO sensor with multiple transceiver channels, including one transmit channel and multiple receive channels. However, the multiple transceiver channels of a MIMO sensor may also include multiple transmit channels and one receive channel, wherein the transmit unit 102 is connected to multiple transmit antennas to form at least one transmit channel, and the receive unit 103 is connected to one receive antenna to form at least one receive channel. It is understood that the multiple transceiver channels of a MIMO sensor are not limited to this; it is sufficient that the total number of transmit and receive channels is greater than or equal to three, i.e., the MIMO sensor has at least two transceiver channels. For example, when the MIMO sensor has two transceiver channels, the MIMO sensor may have one transmit channel (transmit antenna) and two receive channels (receive antennas), or two transmit channels (transmit antennas) and one receive channel (receive antenna).

[0078] Figure 2 A flowchart of a target information matching method is shown. This target matching method performs target information matching based on the comparison of the angles of arrival of two targets in consecutive frames. For example, in Figure 1 In the MIMO sensor shown, the control unit executes the target information matching method described below.

[0079] In step S01, multi-channel echo signals of consecutive frames are received.

[0080] In a frame period of the multi-channel echo signal, the MIMO sensor transmits a radar beam to the surrounding environment via the transmitting antenna Tx, and then receives a return signal of the radar beam via the receiving antennas Rx1 to Rx4. The receiving unit is connected with the plurality of receiving antennas Rx1 to Rx4 to form a plurality of transceiving channels, and the return signals received by different antennas are respectively processed. In each frame period, the MIMO sensor can receive the multi-channel echo signal via the plurality of receiving antennas. In consecutive frame periods, the MIMO sensor can obtain the multi-channel echo signals of consecutive frames.

[0081] In step S02, the multi-channel echo signals are respectively processed to obtain multi-channel range-Doppler two-dimensional data.

[0082] The signal processing of the echo signal includes analog signal processing and digital signal processing. The analog signal processing includes mixing and converting the echo signal to obtain an analog input signal. The digital signal processing includes converting the analog input signal into a digital signal and performing a plurality of data processing processes: Fourier transform, target detection, angle detection and point cloud imaging, wherein the Fourier transform can include one-dimensional FFT transform (1D-FFT) and two-dimensional FFT transform (2D-FFT). The one-dimensional FFT transform (1D-FFT) includes, for example, range dimension Fourier transform and velocity dimension Fourier transform, respectively obtaining range dimension data and velocity dimension data. The two-dimensional FFT transform (2D-FFT) includes, for example, range dimension Fourier transform and Doppler dimension Fourier transform performed in sequence, thereby obtaining range-Doppler two-dimensional data.

[0083] In this step, the multi-channel echo signals of consecutive frames of the MIMO sensor are respectively processed as described above, and for the echo signal of each frame, multi-channel range-Doppler two-dimensional data is respectively obtained.

[0084] In step S03, the receiving vectors of a plurality of targets are obtained according to the multi-channel range-Doppler two-dimensional data.

[0085] In the range-Doppler two-dimensional data of each channel, a peak value is searched on a range-Doppler two-dimensional complex plane to detect a target, and the range and velocity information of the target are respectively obtained from the range and velocity coordinates (r, v) of the range-Doppler unit. Therefore, in the range-Doppler two-dimensional data of each channel, a plurality of range-Doppler units are detected, for example, each corresponding to a target, and the range-Doppler unit has corresponding target information, i.e., the range and velocity information of the target.

[0086] Further, the range-Doppler units in the multi-channel range-Doppler two-dimensional data are grouped into the receiving vectors of the same target according to the corresponding relationship.

[0087] In this step, based on a frame of multi-channel range-Doppler two-dimensional data, the receiving vector RV_VEC of the detected target in the frame is obtained, as shown in equation (1),

[0088] RV_VEC = [RV_DAT1(r, v), RV_DAT2(r, v), RV_DAT3(r, v), RV_DAT4(r, v)] (1)

[0089] Wherein, RV_DAT1(r, v), RV_DAT2(r, v), RV_DAT3(r, v), RV_DAT4(r, v) are a set of elements of the receiving vector, respectively representing the complex value of the detected target at coordinates (r, v) on the range-Doppler two-dimensional complex plane of the multi-channel range-Doppler two-dimensional data.

[0090] In step S04, the receiving vectors of the multiple targets are respectively correlated to obtain the angles of arrival of the multiple targets.

[0091] In this step, the receiving vector of the detected target is correlated with the steering vector, i.e. the vector inner product operation, to obtain the correlation spectrum. The angle corresponding to the peak on the correlation spectrum is the angle of arrival of the detected target.

[0092] In steps S05 to S07, two targets with close angles of arrival in adjacent frames are matched to the same actual object.

[0093] In this step, two targets in adjacent frames are selected, and the angles of arrival of the two targets are compared. If the angles of arrival of the two targets are close, it is determined that the target information of the two targets matches the same actual object. If the angles of arrival of the two targets are not close, it is determined that the target information of the two targets does not match the same actual object, and two targets in adjacent frames are reselected for comparison of the angles of arrival. The above steps of target selection and angle of arrival comparison in adjacent frames are repeated until all targets in adjacent frames are matched.

[0094] The existing target information matching method matches the target information based on the comparison result of the angles of arrival of two targets in consecutive frames. The signal processing process of steps S01 to S04 is digital beam forming (DBF), in which multi-channel echo signals are obtained using an array antenna, and digital beam synthesis is performed to improve the signal-to-noise ratio.

[0095] In digital beam synthesis, the correlation calculation for each target's receiving vector includes vector inner product operation between the receiving vector and the steering vector. Since the steering vector is a function of the scanning angle of the radar beam, the signal processing procedure for obtaining the target's angle of arrival needs to perform multiple digital beam forming (DBF) operations related to the scanning angle of the radar beam. Assuming that the scanning angle range of the digital beam forming is -60 degrees to 60 degrees with 1 degree interval, the angle of arrival calculation for each target needs 120 correlation calculations, and the angle of arrival comparison for two targets needs 240 correlation calculations.

[0096] Therefore, the signal processing procedure of the existing target information matching method is relatively complex, and the correlation calculation is time-consuming, which degrades the real-time performance of the multi-channel echo signal processing.

[0097] Figure 3 A flow chart of a target information matching method according to an embodiment of the present application is shown. The target matching method performs target information matching based on the receiving vector correlation coefficient results of two targets in consecutive frames. For example, in the MIMO sensor shown in Figure 1 The control unit performs the target information matching method described below.

[0098] In step S11, the multi-channel echo signal of consecutive frames is received.

[0099] In the frame period of the multi-channel echo signal, the MIMO sensor transmits a radar beam to the surrounding environment via the transmitting antenna Tx, and then receives the echo signal of the radar beam via the receiving antennas Rx1 to Rx4. The receiving unit is connected with the multiple receiving antennas Rx1 to Rx4 to form multiple transceiving channels, and the echo signals received by different antennas are respectively processed. In each frame period, the MIMO sensor can receive the multi-channel echo signal via multiple receiving antennas. In consecutive frame periods, the MIMO sensor can obtain the multi-channel echo signal of consecutive frames.

[0100] In step S12, the multi-channel echo signal is respectively processed to obtain multi-channel range-Doppler two-dimensional data.

[0101] The signal processing of the echo signals comprises analog signal processing and digital signal processing. The analog signal processing comprises mixing and converting the echo signals to obtain analog input signals. The digital signal processing comprises converting the analog input signals to digital signals and performing a plurality of data processing procedures: Fourier transform, target detection, angle detection and point cloud imaging, wherein the Fourier transform can comprise one-dimensional FFT transform (1D-FFT) and two-dimensional FFT transform (2D-FFT). The one-dimensional FFT transform (1D-FFT) comprises, for example, a range dimension Fourier transform and a velocity dimension Fourier transform, respectively obtaining range dimension data and velocity dimension data. The two-dimensional FFT transform (2D-FFT) comprises, for example, a range dimension Fourier transform followed by a Doppler dimension Fourier transform, thereby obtaining range-Doppler two-dimensional data.

[0102] Referring to Figure 4 The adjacent frames of the echo signals of the MIMO sensor comprise a first frame A and a second frame B, each frame comprising echo signals of four receiving channels. The echo signals of the four receiving channels of the first frame A are respectively subjected to the signal processing procedures of the above steps, thereby obtaining four-channel range-Doppler two-dimensional data RV_DAT_A1 to RV_DAT_A4. The echo signals of the four receiving channels of the second frame B are respectively subjected to the signal processing procedures of the above steps, thereby obtaining four-channel range-Doppler two-dimensional data RV_DAT_B1 to RV_DAT_B4.

[0103] In this step, the multi-channel echo signals of the consecutive frames of the MIMO sensor are respectively subjected to the above signal processing, and for the echo signals of each frame, multi-channel range-Doppler two-dimensional data are respectively obtained.

[0104] In step S13, the receiving vectors of a plurality of targets are obtained according to the multi-channel range-Doppler two-dimensional data.

[0105] In the range-Doppler two-dimensional data of each channel, a peak value is searched on a range-Doppler two-dimensional complex plane to detect a target, and the range and velocity information of the target are respectively obtained from the range and velocity coordinates (r, v) of the range-Doppler unit. Therefore, a plurality of range-Doppler units are detected in the range-Doppler two-dimensional data of each channel, each range-Doppler unit corresponding to a plurality of channels in a target, and the range-Doppler unit has corresponding target information, i.e., the range and velocity information of the target.

[0106] For example, referring to Figure 5Based on the first frame A-echo signal from the MIMO sensor, the range-Doppler two-dimensional data RV_DAT_A1 of the first channel can be obtained. The target TA is detected by searching for peaks. The target TA can be represented on the range-Doppler two-dimensional complex plane as the coordinates RV_DAT_A1(ra,va) of a range-Doppler cell, where ra represents the range of the target TA and va represents the velocity of the target TA. For the target TA detected in the first frame, the complex values ​​at coordinates (ra,va) on the range-Doppler two-dimensional complex plane of four data channels can be obtained: RV_DAT_A1(ra,va), RV_DAT_A2(ra,va), RV_DAT_A3(ra,va), and RVDAT_A4(ra,va).

[0107] and Figure 5 Similarly, for the target TB detected in the second frame, the complex values ​​at coordinates (rb,vb) on the distance-Doppler two-dimensional complex plane of the four data channels can be obtained: RV_DAT_B1(rb,vb), RV_DAT_B2(rb,vb), RV_DAT_B3(rb,vb), and RV_DAT_B4(rb,vb). The target TA detected in the first frame and the target TB detected in the second frame are the same or different targets detected in the multi-channel echo signal of consecutive frames.

[0108] Furthermore, the range-Doppler cells in the multi-channel range-Doppler two-dimensional data are combined to form the target's receiving vector according to their correspondence with the same target.

[0109] Based on the multi-channel range-Doppler two-dimensional data of the first frame, the received vector RV_VEC_A of the first target TA in the first frame is obtained, as shown in equation (2).

[0110] RV_VEC_A=[RV_DAT_A1(ra,va),RV_DAT_A2(ra,va),RV_DAT_A3(ra,va),RV_DAT_A4(ra,va)] (2)

[0111] Among them, RV_DAT_A1(ra,va), RV_DAT_A2(ra,va), RV_DAT_A3(ra,va), and RV_DAT_A4(ra,va) are a set of elements of the receiving vector, which respectively represent the complex values ​​of the target TA at the coordinates (ra,va) on the multi-channel range-Doppler two-dimensional data range-Doppler two-dimensional complex plane.

[0112] Based on the multi-channel range-Doppler two-dimensional data of the second frame, the received vector RV_VEC_B of the second target TB in the second frame is obtained, as shown in equation (3).

[0113] RV_VEC_B=[RV_DAT_B1(rb,vb),RV_DAT_B2(rb,vb),RV_DAT_B3(rb,vb),RV_DAT_B4(rb,vb)] (3)

[0114] Among them, RV_DAT_B1(rb,vb), RV_DAT_B2(rb,vb), RV_DAT_B3(rb,vb), and RV_DAT_B4(rb,vb) are a set of elements of the received vector, which respectively represent the complex values ​​of the target TB at the coordinates (rb,vb) on the multi-channel distance-Doppler two-dimensional data distance-Doppler two-dimensional complex plane.

[0115] For multiple targets detected in the first and second frames, the corresponding receiving vectors are calculated based on multi-channel range-Doppler two-dimensional data.

[0116] In step S14, two targets in adjacent frames are selected.

[0117] In step S15, the received vectors of two targets in adjacent frames are correlated to obtain a correlation coefficient. The value of the correlation coefficient is positively correlated with the degree of approximation of the angle of arrival between the two targets.

[0118] In step S16, it is determined whether the correlation coefficient is greater than a predetermined value. If it is greater than the predetermined value, step S17 is executed to determine that the two selected targets match the same actual object. If it is less than or equal to the predetermined value, it is determined that the two selected targets do not match the same actual object, and the process returns to step S14, continuing to execute steps S14 to S16.

[0119] In steps S14 to S17 above, for example, for the first target TA selected in the first frame, an arbitrary second target TB is selected in the second frame. Multiple targets in the second frame are traversed and compared to obtain two targets that match the same actual object in adjacent frames.

[0120] and Figure 2 In the conventional target information matching method shown, the angles of arrival of the two targets are different. The target matching method according to the embodiment of the present invention performs target information matching based on the correlation coefficient of the received vectors of the two targets in consecutive frames.

[0121] In this embodiment, the correlation coefficient corr_coe of the first target TA and the second target TB is shown in equation (4).

[0122] corr_coe=

[0123] |RV_VEC_A*(RV_VEC_B) H| | RV_VEC_A | * | RV_VEC_B | (4)

[0124] wherein RV_VEC_A represents the receiving vector of the first target TA, RV_VEC_B represents the receiving vector of the second target TB, H represents conjugate and transpose, / represents division, and || represents vector norm.

[0125] The calculation method of vector norm is known, for example, the calculation formula of the vector norm of the receiving vector RV_VEC_A of the first target TA is shown in formula (5),

[0126] | RV_VEC_A | = [RV_VEC_A * (RV_VEC_A) H ] 1 / 2 (5)

[0127] wherein RV_VEC_A represents the receiving vector of the first target TA, and H represents conjugate and transpose.

[0128] Optionally, the receiving vector can be windowed first to suppress the sidelobe of the DBF spectrum, and then the above DOA matching operation (such as conjugate processing) is performed.

[0129] For example, the receiving vector RV_VEC_A of the first target TA and the receiving vector RV_VEC_B of the second target TB can be weighted, that is, all elements of the receiving vector RV_VEC_A of the first target TA and the receiving vector RV_VEC_B of the second target TB are multiplied by a complex value (which can be pre-calculated or set according to actual requirements or big data analysis), and then the above DOA matching operation is performed to improve the accuracy of target matching and reduce the calculation amount.

[0130] The target information matching method according to the embodiment of the application matches target information based on the comparison result of the correlation coefficient of two targets in consecutive frames and the reference value. The steps S11 to S13 are basically the same as the corresponding steps in the conventional target information matching method. However, the steps S14 to S17 directly calculate the correlation coefficient according to the receiving vectors of two targets in consecutive frames, and evaluate the matching degree of the angles of arrival of two targets according to the size of the correlation coefficient. The value of the correlation coefficient is positively correlated with the approximate degree of the angle of arrival between the first target and the second target, that is, the greater the correlation coefficient, the higher the matching degree of the angle of arrival can be considered.

[0131] Optionally, in the above embodiment, for the scenario of matching DOA information, a correlation coefficient threshold can also be set based on big data analysis and other operations, that is, if the obtained correlation coefficient is greater than or equal to the correlation coefficient threshold, it is considered that the two targets match in the DOA dimension, and if the obtained correlation coefficient is less than the correlation coefficient threshold, it is considered that the two targets are not corresponding to the same object (target).

[0132] The target information matching method described above does not need to actually calculate the angles of arrival of the targets, and thus can simplify the complex calculation process of digital beam synthesis. In particular, since the vector inner product operation between the received vector and the steering vector does not need to be performed, the number of times of digital beam forming (DBF) operations related to the scanning angle of the radar beam can be significantly reduced. Assuming that the scanning angle range of the digital beam forming is -60 degrees to 60 degrees with an interval of 1 degree, the correlation coefficient calculation of the received vectors of the two targets only needs to be performed once, while the traditional method needs to be performed 240 times, and thus the timeliness of the signal data processing can be significantly improved.

[0133] Therefore, the signal processing process of the target information matching method according to the embodiment of the application simplifies the correlation calculation complexity, significantly shortens the time consumption, and can significantly improve the real-time performance of the multi-channel echo signal processing. In particular, when the PRFs of two adjacent frames are set to be different to measure the speed of a high-speed target, since the actual DOA value of the target does not need to be obtained, the DOA information of the two frames can be matched by performing the DBF and other complex operations in the target matching process, and thus the timeliness can be further improved.

[0134] In the above embodiment, the target information matching method based on the comparison result of the correlation coefficient of the two targets in the continuous frames with the reference value is described, in which the two targets are the same or different targets detected in the multi-channel echo signals of the continuous frames, and thus the object tracking can be performed in the continuous frames. The target information matching method is based on the arrival angle approximation judgment method, and if the arrival angles of the two targets are approximate, it is judged that the two targets correspond to the same actual object, and thus the object differentiation can be performed in the continuous frames.

[0135] In an alternative embodiment, the same signal processing method can be used to obtain the correlation coefficient of the two targets in the same frame, and based on the comparison result of the correlation coefficient of the two targets in the same frame with the reference value, the approximation degree of the arrival angles of the two targets can be judged, and thus the object differentiation can be performed in the same frame.

[0136] It is to be understood that the terminology "including", "comprising", or any other variation thereof, is intended to cover a non-exclusive inclusion such that process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises a... " does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0137] In accordance with the practices of the present application, these embodiments have been described in relation to the above-described embodiments thereof, which are intended to be illustrative only and not restrictive of the application. There many modifications and variations to the embodiments described herein that will be apparent to those of ordinary skill in the art. It is therefore contemplated that the application shall cover any and all modifications and variations of the various embodiments described herein that fall within the scope of the present application. It is also contemplated that the application shall cover the combination of any alternative embodiment with any one or more of the embodiments previously described herein that fall within the scope of the present application. The specification and drawings should be regarded as illustrative only and should not be considered restrictive in character. The scope and spirit of the application are indicated by the appended claims.

Claims

1. A method for judging the approximation of the angle of arrival between targets, applied to a MIMO radar, the method comprising: obtaining a receiving vector of a first target and a receiving vector of a second target respectively according to the processing result of a multi-channel echo signal; calculating a correlation coefficient of the receiving vectors of the first target and the second target; and judging the approximation of the angle of arrival between the first target and the second target according to the correlation coefficient. The receiving vector comprises distance information and velocity information. The calculation of the correlation coefficient of the receiving vectors of the first target and the second target comprises: performing conjugate correlation processing on the receiving vectors of the first target and the second target to obtain the correlation coefficient; wherein the value of the correlation coefficient is positively correlated with the approximation of the angle of arrival between the first target and the second target. The first target and the second target are different targets detected in the same frame of the multi-channel echo signal. The first target and the second target are the same or different targets detected in consecutive frames of the multi-channel echo signal.

2. The method of claim 1, wherein, 6.A method for matching target information, applied to a MIMO radar, the method comprising: receiving a multi-channel echo signal of consecutive frames; obtaining a receiving vector of a first target and a receiving vector of a second target respectively in adjacent frames of the consecutive frames according to the processing result of the multi-channel echo signal; calculating a correlation coefficient of the receiving vectors of the first target and the second target; and judging whether the first target and the second target match the same actual object according to the correlation coefficient by using the method for judging the approximation of the angle of arrival between targets according to any one of claims 1 to 5.

3. The method of claim 1, wherein, The receiving vector comprises distance information and velocity information. The calculation of the correlation coefficient of the receiving vectors of the first target and the second target comprises: performing conjugate correlation processing on the receiving vectors of the first target and the second target to obtain the correlation coefficient; wherein the value of the correlation coefficient is positively correlated with the approximation of the angle of arrival between the first target and the second target. The adjacent frames comprise a first frame and a second frame, and the first target and the second target are targets detected in the first frame and the second frame respectively.

4. The method of claim 1, wherein, The step of obtaining a receiving vector of a first target and a receiving vector of a second target respectively in adjacent frames of the consecutive frames comprises: performing signal processing on the multi-channel echo signals of the adjacent frames respectively to obtain multi-channel range-Doppler two-dimensional data of the first frame; detecting the first target by searching for a peak value in the multi-channel range-Doppler two-dimensional data of the first frame; and detecting the second target by searching for a peak value in the multi-channel range-Doppler two-dimensional data of the second frame.

5. The method of claim 1, wherein, The first target corresponds to a first group of range-Doppler cells in the multi-channel range-Doppler two-dimensional data of the first frame, and the second target corresponds to a second group of range-Doppler cells in the multi-channel range-Doppler two-dimensional data of the second frame. The coordinate parameters of each cell in the first group of range-Doppler cells and the second group of range-Doppler cells in the corresponding range-Doppler two-dimensional data comprise distance information and velocity information. ​ ​ ​ ​ ​ 7. The method of claim 6, wherein, ​ 8. The method of claim 6, wherein, ​ ​ ​ 9. The method of claim 6, wherein, ​ 10. The method of claim 9, wherein, ​ ​ ​ ​ 11. The method of claim 10, wherein, ​ ​ 12. The method of claim 11, wherein, The receiving vector of the first target comprises a first set of elements, which respectively represent complex values of the first set of range-Doppler units at corresponding coordinates on a range-Doppler two-dimensional complex plane, and the receiving vector of the second target comprises a second set of elements, which respectively represent complex values of the second set of range-Doppler units at corresponding coordinates on the range-Doppler two-dimensional complex plane.

13. The method of claim 6, wherein, The correlation coefficient of the receiving vectors of the first target and the second target is calculated by using the following formula: corr_coe = RV_VEC_A H / | | RV_VEC_A | | * RV_VEC_B H / | | RV_VEC_B | | |RV_VEC_A*(RV_VEC_B) H | / (|RV_VEC_A|*|RV_VEC_B|) wherein RV_VEC_A represents the receiving vector of the first target TA, RV_VEC_B represents the receiving vector of the second target TB, H represents conjugate transpose, / represents division, and | | represents vector modulus.

14. The method of claim 6, wherein, If the correlation coefficient is greater than a predetermined value, it is determined that the first target and the second target match the same actual object.

15. The method of claim 14, wherein, If the correlation coefficient is less than or equal to the predetermined value, it is determined that the first target and the second target do not match the same actual object, and the angle of arrival approximation degree determination method traverses multiple targets detected in the continuous frames to obtain the first target and the second target matching the same actual object.

16. A MIMO radar, comprising: a plurality of transceiving channels for receiving a multi-channel echo signal; and a signal processing unit for performing signal processing on the multi-channel echo signal and obtaining receiving vectors of a first target and a second target respectively according to a processing result of the signal processing, wherein the signal processing unit further calculates a correlation coefficient of the receiving vectors of the first target and the second target, and determines an angle of arrival approximation degree of the first target and the second target according to the correlation coefficient. The receiving vector comprises range information and velocity information.

17. The MIMO radar of claim 16, wherein, The calculation of the correlation coefficient of the receiving vectors of the first target and the second target comprises:

18. The MIMO radar of claim 17, wherein, performing conjugate correlation processing on the receiving vectors of the first target and the second target to obtain the correlation coefficient; wherein a value of the correlation coefficient is positively correlated with an angle of arrival approximation degree between the first target and the second target. The plurality of transceiving channels comprises:

19. The MIMO radar of claim 16, wherein, a plurality of antennas, which comprise a combination of at least one transmitting antenna and a plurality of receiving antennas, or a combination of a plurality of transmitting antennas and at least one receiving antenna; a transmitting unit connected to the transmitting antennas in the plurality of antennas to provide at least one transmitting channel; a receiving unit connected to the receiving antennas in the plurality of antennas to provide at least one receiving channel, wherein a total number of the at least one transmitting channel and the at least one receiving channel is greater than or equal to 3.

20. The MIMO radar according to claim 19, further comprising: a control unit connected to the transmitting unit and the receiving unit, the control unit controls the transmitting unit to generate a transmitting signal, which is converted into a radar beam via the transmitting antennas in the plurality of antennas, and controls the receiving unit to obtain a multi-channel echo signal via the receiving antennas in the plurality of antennas. ​ 21. The MIMO radar of claim 16, wherein, The first target and the second target are the same or different targets detected in the continuous frame multichannel echo signals.

22. The MIMO radar of claim 21, wherein, The signal processing unit obtains a receiving vector of the first target and the second target in adjacent frames of the continuous frames respectively.

23. The MIMO radar of claim 21, wherein, The signal processing unit determines whether the first target and the second target match the same actual object according to the correlation coefficient.

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