Millimeter-wave radar and target detection method based on millimeter-wave radar

Abstract

The present invention provides a millimeter-wave radar and a target detection method based on the millimeter-wave radar. The millimeter-wave radar includes a main-chip radar and a slave-chip radar. The main-chip radar includes a first chip, four transmitting antennas coupled to the first chip, and four first receiving antennas; the slave-chip radar includes a second chip and four second receiving antennas coupled to the second chip; wherein, the four transmitting antennas are arranged at equal intervals along a first direction; the four first receiving antennas are arranged in sequence along the first direction on a first side of the four transmitting antennas, and the four second receiving antennas are arranged in sequence along the first direction on a second side of the four transmitting antennas; the control timings of the four transmitting antennas, the four first receiving antennas, and the four second receiving antennas are the same, and the phases of the millimeter waves transmitted by the four transmitting antennas are sequentially spaced by 45 degrees.

Description

Technical Field

[0001] The present invention relates to the technical field of millimeter-wave radars, and in particular, to a millimeter-wave radar and a target detection method based on the millimeter-wave radar. Background Art

[0002] Existing millimeter-wave radars, such as the millimeter-wave radar disclosed in the patent text summary with the publication number CN211123248U, usually adopt a near-far scanning antenna design, and there will be detection blind spots where the distance is greater than 70 meters and the angle is greater than ±4°, which is not suitable for large-scale perimeter detection. For millimeter-wave radars suitable for large-scale perimeter detection, the number of transmitting antennas and receiving antennas is usually large, resulting in a large size of the millimeter-wave radar; and the requirements for the control chip are high, resulting in a high cost of the millimeter-wave radar. Summary of the Invention

[0003] The present invention provides a millimeter-wave radar and a target detection method based on the millimeter-wave radar. This solution can be realized with fewer antennas while ensuring the detection accuracy of the millimeter-wave radar, so the size of the millimeter-wave radar can be reduced, and miniaturization of the millimeter-wave radar can be achieved.

[0004] To solve the above technical problems, the first technical solution provided by the present invention is: to provide a millimeter-wave radar, including:

[0005] A main-chip radar, the main-chip radar includes a first chip and 4 transmitting antennas and 4 first receiving antennas coupled to the first chip;

[0006] A slave-chip radar, the slave-chip radar includes a second chip and 4 second receiving antennas coupled to the second chip;

[0007] Wherein, the 4 transmitting antennas are arranged at equal intervals along a first direction; the 4 first receiving antennas are arranged in sequence along the first direction on the first side of the 4 transmitting antennas, and the 4 second receiving antennas are arranged in sequence along the first direction on the second side of the 4 transmitting antennas;

[0008] The control timings of the 4 transmitting antennas, the 4 first receiving antennas, and the 4 second receiving antennas are the same, and the phases of the millimeter waves transmitted by the 4 transmitting antennas are sequentially spaced by 45 degrees.

[0009] To solve the above technical problems, the second technical solution provided by the present invention is: to provide a target detection method based on a millimeter-wave radar, the millimeter-wave radar is the millimeter-wave radar described above, and the target detection method includes:

[0010] The 4 transmitting antennas of the millimeter-wave radar synchronously transmit transmission signals of frequency-modulated continuous waves with phases sequentially spaced by 45 degrees; and

[0011] The received signals returned by detecting the target are synchronously received through the four first receiving antennas and the four second receiving antennas of the millimeter-wave radar;

[0012] Sampling the received signals of each receiving antenna to obtain sampled signals;

[0013] Performing two-dimensional Fourier transform on the sampled signals of each receiving antenna to obtain the radar range and Doppler velocity of each receiving antenna detecting the target;

[0014] Obtaining the horizontal angle and pitch angle of the millimeter-wave radar relative to the target by using the radar range and Doppler velocity of each receiving antenna detecting the target;

[0015] Detecting the target by using the horizontal angle and pitch angle.

[0016] The beneficial effects of the present invention, different from the prior art, the present application provides a millimeter-wave radar and a target detection method based on the millimeter-wave radar. Among them, the millimeter-wave radar provided by the present application can detect a target about 200 meters within a horizontal detection range of ±60°. The angular resolution is 1.7°. It has a vertical detection range of ±15°, and can measure the pitch angle of the target, realizing precise detection and positioning of the position of the target. In addition, the solution in this scheme uses four antennas to simultaneously send out transmission signals, which can detect farther targets. And this scheme uses a sparse matrix antenna through an angle deblurring algorithm, which can achieve the same angular resolution with fewer antennas and can detect information such as the pitch angle. That is, it can be realized with fewer antennas while ensuring the detection accuracy of the millimeter-wave radar, so the size of the millimeter-wave radar can be reduced, and the miniaturization of the millimeter-wave radar can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings, where:

[0018] Figure 1 is a schematic structural diagram of an embodiment of the millimeter-wave radar provided by the present application;

[0019] Figure 2 is Figure 1 a schematic structural diagram of the antenna arrangement in the millimeter-wave radar shown;

[0020] Figure 3 isFigure 1 Schematic diagram of the equivalent antenna setting structure in the millimeter-wave radar shown

[0021] Figure 4 It is a schematic flowchart of an embodiment of a target detection method based on a millimeter-wave radar provided by this application

[0022] Figure 5 It is a coordinate graph established by using the candidate Doppler velocity and the candidate radar distance in the solution of this application

[0023] Figure 6 It is a distribution coordinate graph of the angle determination values in the data groups AzimuthFFT and AzimuthFFT2 in the solution of this application Specific embodiments

[0024] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the protection scope of this application

[0025] Please refer to Figure 1 and Figure 2 , Figure 1 It is a schematic structural diagram of an embodiment of the millimeter-wave radar provided by this application Figure 2 is Figure 1 Schematic diagram of the antenna setting structure in the millimeter-wave radar shown

[0026] The millimeter-wave radar 10 includes a main-chip radar 110 and a slave-chip radar 120

[0027] The main-chip radar 110 includes a first chip 111, 4 transmitting antennas 112 coupled to the first chip 111, and 4 first receiving antennas 113; the slave-chip radar 120 includes a second chip 121 and 4 second receiving antennas 122 coupled to the second chip 121; wherein, the 4 transmitting antennas 112 are arranged at equal intervals along the first direction A; the 4 first receiving antennas 113 are arranged in sequence along the first direction A on the first side of the 4 transmitting antennas 112, and the 4 second receiving antennas 122 are arranged in sequence along the first direction A4 on the second side of the 4 transmitting antennas 112; the control timings of the 4 transmitting antennas 112, the 4 first receiving antennas 113, and the 4 second receiving antennas 122 are the same, and the phases of the millimeter waves transmitted by the 4 transmitting antennas 112 are sequentially spaced 45 degrees

[0028] In this embodiment, within a horizontal detection range of ±60°, the millimeter-wave radar 10 can detect targets about 200 meters away, with an angular resolution of 1.7°, a vertical detection range of ±15°, and can measure the elevation angle of the target, achieving precise detection and positioning of the target's position. Therefore, the solution in this scheme uses 4 antennas to simultaneously transmit signals, which can detect farther targets. Moreover, this scheme uses a sparse matrix antenna and an angle deblurring algorithm, which can achieve the same angular resolution with fewer antennas and can detect information such as the elevation angle.

[0029] Among them, in some embodiments, the spacing between the 4 transmitting antennas 112 is 4 times the wavelength L of the transmitted millimeter wave; the distance between the two middle receiving antennas among the 4 first receiving antennas 113 and the 4 second receiving antennas 122 is 1.5 times the wavelength L (i.e., 1.5L. When the distance description is m times the wavelength L later, it can be analogously inferred that this spacing is m*L), and the distance from each receiving antenna at the edge position to the nearest receiving antenna is 0.25 times the wavelength L.

[0030] In some embodiments, the two middle receiving antennas among the 4 first receiving antennas 113 and the 4 second receiving antennas 122 are arranged in a staggered manner with the other receiving antennas along the second direction B.

[0031] Among them, the arrangement of the 4 first receiving antennas 113 and the 4 second receiving antennas 122 on the relative sides of the 4 transmitting antennas 112 is the same. The following takes the arrangement of the 4 first receiving antennas 113 as an example for illustration.

[0032] The 4 first receiving antennas 113 are arranged in sequence along the first direction A on the first side of the 4 transmitting antennas 112. Among them, for the two first receiving antennas 113 that are closest and farthest from the 4 transmitting antennas 112, two outer receiving antennas can be set outside the 4 first receiving antennas 113, and the two first receiving antennas 113 located between these two receiving antennas are the two middle receiving antennas in the middle of the 4 outer first receiving antennas 113.

[0033] Among them, the spacings in the first direction A between one of the two outer receiving antennas and the 4 transmitting antennas 112 that is closest to the transmitting antenna 112 are 1 times the wavelength L and 3 times the wavelength L respectively. That is, the spacing between the two outer receiving antennas is 2 times the wavelength L.

[0034] Among them, the spacing between the two middle receiving antennas is 1.5 times the wavelength L respectively, and the spacing between the two middle receiving antennas and the 4 first receiving antennas 113 in the second direction B is 1.5 times the wavelength L.

[0035] Further, in this embodiment, the length of the transmitting antenna 112 is 4 times the wavelength L, and the second direction B is parallel to the length direction of the transmitting antenna 112. The length of the first receiving antenna 113 is 3 times the wavelength L. Similarly, the second direction B is arranged parallel to the length direction of the first receiving antenna 113.

[0036] Among them, the connecting lines between the centers of the two outer receiving antennas and the centers of the 4 transmitting antennas 112 are located on the same straight line.

[0037] In this embodiment, the control timings of the 4 first receiving antennas 113 and the 4 second receiving antennas 122 are the same, and the phases of the millimeter waves transmitted by the 4 transmitting antennas 112 are sequentially spaced by 45 degrees. The millimeter waves transmitted by the 4 transmitting antennas 112 can detect a preset target.

[0038] Therefore, each receiving antenna (including the first receiving antenna 113 and the second receiving antenna 122) can be used to receive the received signal returned after the transmitted signal transmitted by the 4 transmitting antennas 112 detects a preset target, and each receiving antenna can receive 4 sets of transmitted signals with 4 different phases transmitted by the 4 transmitting antennas 112. That is, the 4 first receiving antennas 113 and the 4 second receiving antennas 122 can receive a total of 4*4 + 4*4 = 32 sets of received signals. Among them, each set of received signals can be expressed as the received signal corresponding to the millimeter wave transmitted signal transmitted by one of the transmitting antennas 112 received by one receiving antenna.

[0039] Among them, since the 4 first receiving antennas 113 and the 4 second receiving antennas 122 can be equivalent to 32 receiving antennas respectively receiving one set of received signals.

[0040] Among them, please refer to Figure 3 , Figure 3 is Figure 1 the schematic diagram of the equivalent antenna setting structure in the millimeter wave radar shown.

[0041] Among them, the equivalent antenna row group includes 32 receiving antennas 101 arranged in two rows. There are 16 receiving antennas 101 in each row.

[0042] Among them, the 16 receiving antennas 101 in the first row are arranged at equal intervals, and the distance between two adjacent receiving antennas 101 is 2 times the wavelength. Among the 16 receiving antennas 101 in the second row, two adjacent receiving antennas 101 can form an antenna group. Among them, the distance between the two receiving antennas 101 in each antenna group is 1.5 times the wavelength; the distance between two adjacent antenna groups is 2.5 times the wavelength.

[0043] Among them, the 16 receiving antennas 101 in the first row can be equivalent to 16 groups of received signals corresponding to the two outer transmitting antennas among the 4 transmitting antennas 112 received by the receiving antennas described above; the 16 receiving antennas 101 in the second row can be equivalent to 16 groups of received signals corresponding to the two middle transmitting antennas among the 4 transmitting antennas 112 received by the receiving antennas described above.

[0044] Furthermore, based on the same inventive concept, the present application also provides a target detection method based on a millimeter-wave radar.

[0045] Please refer to Figure 4 , Figure 4 which is a schematic flowchart of an embodiment of a target detection method based on a millimeter-wave radar provided by the present application.

[0046] Specifically, the target detection method in this embodiment can be implemented based on the millimeter-wave radar 10 described above. Among them, the target detection method based on the millimeter-wave radar specifically includes the following steps:

[0047] S310: The 4 transmitting antennas of the millimeter-wave radar synchronously transmit transmitted signals of frequency-modulated continuous waves with a phase difference of 45 degrees in sequence.

[0048] In this step, the 4 transmitting antennas 112 of the millimeter-wave radar can be used to synchronously transmit transmitted signals of frequency-modulated continuous waves with a phase difference of 45 degrees in sequence. Among them, the so-called synchronous transmission means that the time sequences of the transmitted signals emitted by the 4 transmitting antennas 112 are the same. Among them, the transmitted signals emitted by the 4 transmitting antennas only have a phase difference of 45 degrees in sequence. For example, when the phase of the transmitted signal emitted by the first transmitting antenna 112 is 0, the phase of the transmitted signal emitted by the second transmitting antenna 112 is π / 4; the phase of the transmitted signal emitted by the third transmitting antenna 112 is π / 2; the phase of the transmitted signal emitted by the fourth transmitting antenna 112 is 3π / 4.

[0049] S320: The 4 first receiving antennas and 4 second receiving antennas of the millimeter-wave radar synchronously receive the received signals returned after detecting the target by the transmitted signals.

[0050] As in step S310, the transmitted signals emitted by the 4 transmitting antennas 112 can be used to detect the preset position of the target. The 4 first receiving antennas 113 and 4 second receiving antennas 122 of the millimeter-wave radar can then synchronously receive the received signals returned after detecting the target by the transmitted signals.

[0051] Among them, each first receiving antenna 113 and each second receiving antenna 122 can receive the received signals returned after detecting the preset target by the transmitted signals emitted by the 4 transmitting antennas 112.

[0052] For the receiving antennas (including the first receiving antenna 113 and the second receiving antenna 122), the received signals returned after the transmitted signals emitted by the 4 transmitting antennas 112 are detected by the receiving antennas can be expressed as:

[0053]

[0054] where f0 is the starting frequency of the transmitted signal, k is the slope, B is the signal amplitude, and τ is the delay time from the transmitted signal to the received signal.

[0055] Among them, considering that the transmitted signals emitted by the 4 transmitting antennas 112 have a phase difference of 45 degrees in sequence; therefore, the signals received by the 4 first receiving antennas 113 or the 4 second receiving antennas 122 can be expressed as:

[0056]

[0057] where R(t)i corresponds to the received signal corresponding to the i-th transmitting antenna 112 among the 4 transmitting antennas 112 in the first direction.

[0058] S330: Sample the received signal of each receiving antenna to obtain a sampled signal.

[0059] In this step, the received signal of each receiving antenna can be sampled to obtain a sampled signal.

[0060] Specifically, when using this millimeter-wave radar to detect a target, a continuous frequency-modulated continuous wave is required.

[0061] Among them, for the target, this millimeter-wave radar can emit transmitted signals through 4 transmitting antennas 112 respectively, and the receiving antenna can obtain a point position in a frame of image of the target according to the received signal.

[0062] Among them, the transmitting antenna 112 can emit transmitted signals with multiple waveforms. Correspondingly, each receiving antenna can receive received signals with multiple waveforms. In this embodiment, each receiving antenna 101 can mix the received signal and the corresponding transmitted signal to obtain a mixed signal for each antenna. Furthermore, sampling points can be collected from the mixed signal.

[0063] Among them, taking one of the receiving antennas as an example. Each receiving antenna can receive received signals with multiple waveforms.

[0064] Multiple sampling points can be collected on each waveform of the received signal. For example, 512 sampling points can be obtained for each waveform of the received signal acquired by the receiving antenna. And when each transmitting antenna 112 can transmit 512 waveforms, the received signal acquired by the corresponding receiving antenna can have 512 waveforms. Therefore, each receiving antenna can obtain a total of 512 * 512 sampling points.

[0065] In this step, the sampling signal can include multiple sampling points.

[0066] S340: Perform two-dimensional Fourier transform on the sampling signals of each receiving antenna to obtain the radar distance and Doppler velocity of the target detected by each receiving antenna.

[0067] After the sampling signal is obtained, in this step, the data in the sampling signal can be further processed to obtain the radar distance and Doppler velocity of the target detected by each receiving antenna.

[0068] Specifically, by performing two-dimensional Fourier transform on the sampling signal, the radar distance and Doppler velocity of the target detected by the receiving antenna can be obtained respectively.

[0069] In this step, multiple sampling points can be obtained for the received signal of each receiving antenna. Then, the sampling signal corresponding to the received signal of each receiving antenna can be obtained from the received signal of each receiving antenna. Further, after two-dimensional Fourier transform, the radar distance and Doppler velocity of the target detected by each receiving antenna can be obtained.

[0070] The receiving antenna in this step can be the receiving antenna 101 in the equivalent antenna array group as described above. That is, in this step, the radar distances and Doppler velocities of the targets detected by 32 receiving antennas 101 can be obtained respectively.

[0071] Specifically, the two-dimensional Fourier transform of the sampling signal includes:

[0072] Perform the first Fourier transform on the received signal corresponding to each transmitted signal of each transmitting antenna 112 collected by each receiving antenna to obtain multiple candidate radar distances Rh corresponding to each received signal.

[0073] In response to the completion of the first Fourier transform of the received signals corresponding to the transmitted signals in the same frame, perform the second Fourier transform on the candidate radar distances Rh of the receiving antennas obtained to obtain multiple candidate Doppler velocities Vh corresponding to each transmitting antenna of the receiving antenna;

[0074] Determine the largest one among the multiple candidate Doppler velocities Vh corresponding to each transmitting antenna as the Doppler velocity V of the receiving antenna relative to the transmitting antenna, and determine the candidate radar distance Rh corresponding to the Doppler velocity V as the radar distance R of the receiving antenna relative to the transmitting antenna.

[0075] Among them, the Fourier transform can be carried out by the following formula:

[0076]

[0077] Among them, k is the Fourier series = 1 to 512, N = 512, and i = n - 1.

[0078] When performing the first Fourier transform, X(k) represents the value obtained after performing the Fourier transform on multiple sampling points in a waveform received by the receiving antenna, which can be represented as the candidate radar distance Rh. And in this step, a candidate radar distance Rh can be obtained for each sampling point in the receiving antenna 101, that is, multiple sampling points can obtain multiple radar distances Rh. For example, as described above, when the sampling signal of the received signal corresponding to the transmitted signal of each waveform includes 512 sampling points, 512 candidate radar distances Rh can be obtained through the first Fourier transform.

[0079] When performing the second Fourier transform, the multiple candidate radar distances Rh obtained in the first Fourier transform can be further subjected to the second Fourier transform, so that multiple candidate Doppler velocities Vh can be obtained. Select the largest candidate Doppler velocity Vh as the Doppler velocity V of the target, and the candidate radar distance Rh corresponding to the Doppler velocity V is the radar distance R of the target.

[0080] The above millimeter-wave radar 10 can be equivalent to having 32 receiving antennas 101, and the radar distance R and Doppler velocity V when detecting the target in each of the 32 receiving antennas 101 can be calculated.

[0081] Among them, the radar distance R and Doppler velocity V can be used to calculate the distance of the target relative to the radar and the moving speed of the target respectively. Specifically, by multiplying the radar distance R by the preset distance resolution, the distance of the target from the radar can be obtained; by multiplying the Doppler velocity V by the preset speed resolution, the moving speed of the target can be obtained; among them, the distance resolution C is the speed of light, B is the bandwidth; speed resolution: L is the wavelength, and Tf is the time of one frame of transmitted signal.

[0082] In this step, after performing the Fourier T transform twice on the signals received by each receiving antenna, a data group FFTDATA of RxNum * ADCNum * ChripNum can be formed; where RxNum is the number of actual receiving antennas, ADCNum is the number of sampling points of the signals received by the receiving antenna at one time, ChripNum is the number of waveforms transmitted by the transmitting antenna in each frame, and the radar distance R and Doppler velocity V of the detection target of the receiving antenna can be detected.

[0083] In this step, the maximum value among multiple candidate Doppler velocities Vh can be obtained through direct mathematical operations or other algorithms.

[0084] In other embodiments, a coordinate system can also be established with the radar distance R as the first axis X and the Doppler velocity V as the second axis Y; where the first axis X and the second axis Y are perpendicular to each other.

[0085] The step of determining the maximum value among multiple candidate Doppler velocities Vh corresponding to each transmitting antenna 112 as the Doppler velocity V of the receiving antenna 101 relative to the transmitting antenna 112 and determining the candidate radar distance Rh corresponding to the Doppler velocity V as the radar distance R of the receiving antenna 101 relative to the transmitting antenna 112 includes: corresponding multiple candidate Doppler velocities Vh and multiple candidate radar distances Rh to the coordinate system, obtaining a coordinate map, and obtaining the peaks of multiple candidate Doppler velocities Vh and multiple candidate radar distances Rh in the coordinate map, then the Doppler velocity V and radar distance R of the receiving antenna 101 relative to the transmitting antenna 112 can be obtained.

[0086] Specifically, please refer to Figure 5 where Figure 5 is the coordinate map established by using candidate Doppler velocities and candidate radar distances in the solution of this application.

[0087] Among them, the X-axis in the coordinate map is the first axis, denoted as the candidate radar distance Rh; the Y-axis is the second axis, denoted as the candidate Doppler velocity Vh; among them, the Z-axis represents the height value, which can correspond to the energy intensity value of the antenna.

[0088] Among them, the Doppler velocity V of the receiving antenna corresponding to each transmitting antenna relative to the transmitting antenna can be obtained from this coordinate map.

[0089] Specifically, multiple peaks can be found in the modified coordinate diagram. If the peak coordinates corresponding to the first transmitting antenna 112 are (R, V) for the first peak, and the coordinates of the next three consecutive peaks are (R, V + 64), (R, V + 128), and (R, V + 192) in sequence, it indicates the Doppler velocity V of the transmitting antenna 112 corresponding to the first peak at this time relative to the transmitting antenna.

[0090] Furthermore, as Figure 3 shown, the equivalent receiving antenna group includes 32 receiving antennas 101. And the 32 receiving antennas 101 are respectively equivalent to receiving the received signals after detecting the target by 4 transmitting antennas 112. Therefore, the candidate radar distances Rh and the candidate Doppler velocities Vh obtained by the 32 receiving antennas 101 respectively can have 4 peaks in this coordinate diagram, and the four peaks can respectively correspond to the 4 transmitting antennas 112, and the coordinates of the 4 peaks can correspond to the radar distance R and the Doppler velocity V of the 4 transmitting antennas 112.

[0091] Since there is a 45-degree phase difference between two adjacent ones among the 4 transmitting antennas 112; therefore, the interval between two adjacent peaks is 64 bins. Thus, if the peak coordinates corresponding to the first transmitting antenna 112 are (R, V, Z1), which means the radar distance of the first transmitting antenna 112 is R, the Doppler velocity is V, and the energy intensity value can correspond to Z1; then the peak coordinates corresponding to the second transmitting antenna 112 are (R, V + 64, Z2), which means the radar distance of the second transmitting antenna 112 is R, the Doppler velocity is V + 64, and the energy intensity value can correspond to Z2; then the peak coordinates corresponding to the third transmitting antenna 112 are (R, V + 128, Z3), which means the radar distance of the third transmitting antenna 112 is R, the Doppler velocity is V + 128, and the energy intensity value can correspond to Z3; then the peak coordinates corresponding to the fourth transmitting antenna 112 are (R, V + 192, Z4), which means the radar distance of the fourth transmitting antenna 112 is R, the Doppler velocity is V + 192, and the energy intensity value can correspond to Z4.

[0092] S350: Obtain the horizontal angle and elevation angle of the millimeter-wave radar relative to the target by using the radar distance and Doppler velocity detected by each receiving antenna for the target.

[0093] In this step, the horizontal angle and elevation angle of the millimeter-wave radar relative to the target can be further obtained according to the radar distance and Doppler velocity detected by each receiving antenna for the target.

[0094] Specifically, the third Fourier transform can be performed on the Doppler velocity V of the detection target of each receiving antenna 101 obtained in step S340 to obtain the candidate energy intensity Zh of the detection target of each receiving antenna 101; the maximum value among the candidate energy intensity Zh of each receiving antenna 101 is the energy intensity Z of the receiving antenna.

[0095] Furthermore, the horizontal angle θ and pitch angle of the millimeter-wave radar 10 relative to the target can be obtained according to the energy intensity Z of the receiving antenna.

[0096] In this step, calculations can be performed based on 32 equivalent receiving antennas 101 shown in two rows as follows. Figure 3 Among them, first, the Doppler velocity V and radar distance R of the detection target of each of the 16 receiving antennas 101 in the first row are obtained.

[0097] As described above, the 16 receiving antennas 101 in the first row correspond to the two outer transmitting antennas among the 4 transmitting antennas 112 (i.e., the first and fourth transmitting antennas 112 along the first direction A).

[0098] Among them, as shown in Figure 5 the Doppler velocity V and radar distance R of each of the 16 receiving antennas 101 in the first row relative to the detection target of the first and fourth transmitting antennas 112 can be obtained through a coordinate diagram.

[0099] Specifically, as described above, the coordinates of the Doppler velocity V and radar distance R corresponding to the first transmitting antenna 112 in the coordinate diagram are (R, V, Z1); the coordinates of the Doppler velocity V and radar distance R corresponding to the fourth transmitting antenna 112 in the coordinate diagram are (R, V + 192, Z4).

[0100] Therefore, the Doppler velocity V and radar distance R of 8 of the 16 receiving antennas 101 in the first row can be expressed as (R, V); the Doppler velocity V and radar distance R of the other 8 receiving antennas 101 can be expressed as (R, V + 192). Through (R, V) and (R, V + 192), 16 corresponding data can be found in the data group FFTDATA (the 16 data respectively correspond to the Z values corresponding to the X-axis being R, the Y-axis being V and +192 in the coordinate diagram), thereby forming a new data group AzimuthFFT.

[0101] Similarly, the Doppler velocity V and radar range R of 8 out of the 16 receiving antennas 101 in the second row can be expressed as (R, V + 64); the Doppler velocity V and radar range R of the other 8 receiving antennas 101 can be expressed as (R, V + 128). Through (R, V + 64) and (R, V + 128), 16 corresponding data can be found in the data group FFTDATA (the 16 data respectively correspond to the Z values where the X-axis is R, and the Y-axes are V + 64 and + 128 in the coordinate graph), thereby forming a new data group AzimuthFFT2.

[0102] After obtaining the data group AzimuthFFT and the data group AzimuthFFT2, the energy intensity of the detection target of each receiving antenna 101 can be subjected to a third Fourier transform respectively to obtain the candidate angle determination parameter for the detection target of each receiving antenna; among them, each of the data group AzimuthFFT and the data group AzimuthFFT2 includes 16 energy intensities. After the third Fourier transform, the data group AzimuthFFT and the data group AzimuthFFT2 can respectively obtain the candidate angle determination parameter; among them, the maximum value of the candidate angle determination parameters of the data group AzimuthFFT and the data group AzimuthFFT2 can be respectively selected as the angle determination parameter of the data group.

[0103] Specifically, the energy intensity Z of the detection target of each of the 16 receiving antennas 101 obtained in the data group AzimuthFFT and the data group AzimuthFFT2 can be respectively subjected to a third Fourier transform.

[0104] Among them, the data in the data group AzimuthFFT corresponds to the 16 receiving antennas 101 in the first row. Since the 16 receiving antennas 101 in the first row are arranged at equal intervals with a spacing of 2Lamba, there is a time difference in the signals received by each receiving antenna 101 as shown in Formula 4; the phase difference As shown in Formula 5, that is, the value of each data in the data group AzimuthFFT is as shown in Formula 6.

[0105]

[0106]

[0107] A(n) = {1, e j2π*2sin(θ) ., e j2π*4sin(θ) ., e j2π*6sin(θ) ......} (Formula 6)

[0108] Because the phase difference The value range of is (-π~π), so the value range of the horizontal angle θ is (-14.48~14.48). For targets with a horizontal angle greater than this range, angle ambiguity will occur because this solution requires resolving this angle ambiguity. d is the distance between adjacent receiving antennas 101.

[0109] The data in the data group AzimuthFFT2 corresponds to the 16 receiving antennas 101 in the second row. Since the 16 receiving antennas 101 in the second row are arranged at unequal intervals, their phase differences are also unequal, which can be expressed by formula 7, where n = (1~16), and n represents the nth receiving antenna 101 along the first direction A among the 16 receiving antennas 101; for the specific intervals of the 16 receiving antennas 101 in the second row, please refer to the previous text and will not be elaborated here.

[0110] B(n) == {e j2π*0.25sin(θ) , e j2π*1.75sin(θ) , e j2π*4.25sin(θ) , e j2π*5.75 ......}

[0111] = e j2π*0.25sin(θ) {1, e j2π*1.5sin(θ) , e j2π*4sin(θ) , e j2π*5.5sin(θ) ......} = e j2π*0.25sin(θ) {1, e j2π*2sin(θ) *e -j2π*0.5sin(θ) , e j2π*4sin(θ) , e j2π*6sin(θ) *e -j2π*0.5sin(θ) ......} (Formula 7)

[0112] In this step, the data in the data group AzimuthFFT and the data group AzimuthFFT2 are respectively subjected to the third Fourier transform. Specifically, it can be achieved through the following formula 8.

[0113]

[0114] Among them, N1 is the value of Xa(k) when n is odd, and N2 is the value of Xa(k) when n is even. Taking the 16 receiving antennas 101 in the second row as an example, N1 is the value of Xa(k) when n is odd (i.e., the receiving antennas in the odd-numbered columns along the first direction A), and N2 is the value of Xa(k) when n is even (i.e., the receiving antennas in the even-numbered columns along the first direction A). The value of Xa(k) in formula 8 corresponds to the angle determination value obtained according to the energy intensity Z.

[0115] The result is as Figure 6 shown, Figure 6 is the distribution coordinate diagram of the angle determination values in the data groups AzimuthFFT and AzimuthFFT2. Among them,Figure 6 The Z-axis is the energy intensity value in the data set AzimuthFFT or AzimuthFFT2, and the K-axis represents the Fourier series when the energy intensity value in the corresponding data set AzimuthFFT or AzimuthFFT2 is subjected to the third Fourier transform.

[0116] First, find the peak AzimuthBeamIdx = k = 7 in the data set AzimuthFFT of equally spaced receiving antennas. Here, 7 is within the range of (-14.48 to 14.48). Since there is an angle ambiguity for this value, the horizontal angle of the target cannot be directly obtained using this result. The horizontal angle of the target is the horizontal angle of the target relative to the millimeter-wave radar.

[0117] Find the same peak AzimuthBeamIdx and AzimuthBeamIdx2 = 7 + (16 / 2) = 15 in the data set AzimuthFFT2 corresponding to 16 non-equally spaced receiving antennas. The result corresponding to AzimuthBeamIdx is as shown in Equation 9, where k = 7, N1 is the value of Xa(k) when n is odd, and N2 is the value of Xa(k) when n is even. The result corresponding to AzimuthBeamIdx2 is as shown in Equation 10, with k2 = 15. When k = 7, there is an angle ambiguity, and when k2 = 15, there is no angle ambiguity.

[0118]

[0119]

[0120]

[0121] In this step, further, in response to the absence of angle ambiguity in the energy intensity, the horizontal angle and elevation angle of the millimeter-wave radar 10 relative to the target are obtained using the energy intensity.

[0122] As described above, after obtaining the data set AzimuthFFT and the data set AzimuthFFT2, the data in the data set AzimuthFFT and the data set AzimuthFFT2 can be subjected to the third Fourier transform to obtain an angle determination value. Here, the angle determination value is a complex number including a real part real and an imaginary part imag. Therefore, the horizontal angle can be obtained through the imaginary part imag of the complex number of the angle determination value; the elevation angle can be obtained through the real part real and the imaginary part imag of the complex number of the angle determination value.

[0123] Among them, the horizontal angle of the millimeter-wave radar relative to the target can be obtained through the following Equations 11 and 12.

[0124]

[0125]

[0126] Among them, θ in Formula 12 is the horizontal angle of the millimeter-wave radar 10 relative to the target, and there is no angle ambiguity problem for this horizontal angle.

[0127] Regarding the pitch angle of the millimeter-wave radar 10 relative to the target.

[0128] Since the 16 receiving antennas 101 in the second row are along the first direction A, the distance between adjacent two receiving antennas 101 is successively 1.5 times the wavelength L (denoted as 1.5L), 2.5L, 1.5L, 2.5L...

[0129] There is a pitch phase difference between Xa(k) and Xb(k), and between Xa(k) and Xb(k2). is the magnitude of the pitch angle, and the derivation process is shown in Formulas 13 and 14.

[0130]

[0131]

[0132]

[0133] Therefore, the horizontal angle θ and pitch angle of the millimeter-wave radar 10 relative to the target can be obtained by using the energy intensity.

[0134] S360: Detect the target by using the horizontal angle and pitch angle.

[0135] In the steps as described above, the distance, speed of the target relative to the millimeter-wave radar 10, and the horizontal angle θ and pitch angle of the millimeter-wave radar 10 relative to the target can be obtained. Among them, through the above steps, the distance, speed of the millimeter-wave radar 10 relative to a point on the target, and the horizontal angle θ and pitch angle of the millimeter-wave radar 10 relative to a point on the target can be detected.

[0136] Furthermore, the millimeter-wave radar 10 can detect multiple points on the target, so that the approximate outer contour of the target can be calculated, and then the volume of the target can be obtained.

[0137] Among them, in some embodiments of this embodiment, the first chip 111 of the main chip radar 110 can be used to control 4 transmitting antennas 112 to synchronously transmit frequency-modulated continuous wave transmission signals with phases sequentially spaced 45 degrees apart; the step of synchronously receiving the received signals returned by detecting the target through the 4 first receiving antennas 113 and the 4 second receiving antennas 122 of the millimeter-wave radar 10 includes: controlling the 4 first receiving antennas 113 and the 4 second receiving antennas 122 to synchronously receive the received signals through the first chip 111 and the second chip 121.

[0138] In some embodiments of this embodiment, the received signals of each receiving antenna 101 are sampled to obtain sampled signals. The specific steps may include: performing quadrature modulation on the received signals received by each receiving antenna 101; mixing the modulated received signals with the transmission signals of the corresponding transmitting antennas to obtain mixed signals; and sampling the mixed signals to obtain the sampled signals described above.

[0139] In summary, the present application provides a millimeter-wave radar and a target detection method based on the millimeter-wave radar. Among them, within the horizontal detection range of ±60° of the millimeter-wave radar provided by the present application, the millimeter-wave radar 10 can detect targets about 200 meters away, with an angular resolution of 1.7°, and has a vertical detection range of ±15°. Moreover, it can measure the elevation angle of the target to achieve precise detection and positioning of the target's position. In addition, the solution in this scheme uses 4 antennas to simultaneously transmit transmission signals, which can detect farther targets. And this scheme uses a sparse matrix antenna through an angle deblurring algorithm, which can use fewer antennas to achieve the same angular resolution and can detect information such as the elevation angle. That is, it can be realized with fewer antennas while ensuring the detection accuracy of the millimeter-wave radar. Therefore, the size of the millimeter-wave radar can be reduced, and the miniaturization of the millimeter-wave radar can be achieved.

[0140] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied to other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A millimeter-wave radar, characterized in that, Including: A main-chip radar, the main-chip radar includes a first chip, four transmitting antennas coupled to the first chip, and four first receiving antennas; A slave-chip radar, the slave-chip radar includes a second chip and four second receiving antennas coupled to the second chip; Wherein, the four transmitting antennas are arranged at equal intervals along a first direction; the four first receiving antennas are arranged in sequence along the first direction on a first side of the four transmitting antennas, and the four second receiving antennas are arranged in sequence along the first direction on a second side of the four transmitting antennas; The distance between the two middle receiving antennas among the four first receiving antennas and the four second receiving antennas is 1.5 times the wavelength, and the distance between each receiving antenna at the edge position and the nearest receiving antenna is 0.25 times the wavelength; The two middle receiving antennas among the four first receiving antennas and the four second receiving antennas are arranged in a staggered manner with other receiving antennas along a second direction. Among them, the arrangement manners of the four first receiving antennas and the four second receiving antennas on opposite sides of the four transmitting antennas are the same, and the connection lines between the center points of the two outer receiving antennas and the center point of the four transmitting antennas are on the same straight line; The control timings of the four transmitting antennas, the four first receiving antennas, and the four second receiving antennas are the same, and the phases of the millimeter waves transmitted by the four transmitting antennas are sequentially spaced by 45 degrees.

2. The millimeter-wave radar according to claim 1, characterized in that, The interval distance between the four transmitting antennas is 4 times the wavelength of the millimeter wave.

3. A target detection method based on a millimeter-wave radar, characterized in that, The millimeter-wave radar is the millimeter-wave radar according to any one of claims 1 to 2, and the target detection method includes: The four transmitting antennas of the millimeter-wave radar synchronously transmit transmitted signals of frequency-modulated continuous waves with phases sequentially spaced by 45 degrees; and The four first receiving antennas and the four second receiving antennas of the millimeter-wave radar synchronously receive the received signals returned after detecting the target by the transmitted signals; Sampling the received signal of each receiving antenna to obtain a sampled signal; Performing two-dimensional Fourier transform on the sampled signals of each receiving antenna to obtain the radar distance and Doppler velocity of each receiving antenna detecting the target; Obtaining the horizontal angle and pitch angle of the millimeter-wave radar relative to the target by using the radar distance and Doppler velocity of each receiving antenna detecting the target; Detecting the target by using the horizontal angle and pitch angle.

4. The target detection method according to claim 3, characterized in that, The step of performing two-dimensional Fourier transform on the sampled signals of each receiving antenna to obtain the radar distance and Doppler velocity of each receiving antenna detecting the target includes: Performing a first Fourier transform on the received signal corresponding to each transmitted signal of each transmitting antenna collected by each receiving antenna to obtain a plurality of candidate radar distances corresponding to each received signal; In response to the completion of the first Fourier transform of the received signals corresponding to the transmitted signals in the same frame, performing a second Fourier transform on the obtained candidate radar distances of each receiving antenna to obtain the plurality of candidate Doppler velocities of each receiving antenna corresponding to each transmitting antenna; Determine the maximum of the multiple candidate Doppler velocities corresponding to each of the transmitting antennas as the Doppler velocity of the receiving antenna relative to the transmitting antenna, and determine the candidate radar distance corresponding to the Doppler velocity as the radar distance of the receiving antenna relative to the transmitting antenna.

5. The target detection method according to claim 4, characterized in that, The step of performing two-dimensional Fourier transform on the sampling signals of the receiving antennas to obtain the radar distance and Doppler velocity of the target detected by each receiving antenna further includes: Establish a coordinate system with the radar distance as the first axis and the Doppler velocity as the second axis; wherein, the first axis and the second axis are perpendicular to each other; The step of determining the maximum of the multiple candidate Doppler velocities corresponding to each of the transmitting antennas as the Doppler velocity of the receiving antenna relative to the transmitting antenna, and determining the candidate radar distance corresponding to the Doppler velocity as the radar distance of the receiving antenna relative to the transmitting antenna includes: Map the multiple candidate Doppler velocities and the multiple candidate radar distances to the coordinate system to obtain a coordinate map; Determine the maximum of the multiple candidate Doppler velocities corresponding to one of the transmitting antennas as the Doppler velocity of the receiving antenna relative to the transmitting antenna; Use the phase difference between other transmitting antennas and the one transmitting antenna to determine the Doppler velocity of the receiving antenna relative to other transmitting antennas from the coordinate map.

6. The target detection method according to any one of claims 3 to 5, characterized in that, The step of obtaining the horizontal angle and pitch angle of the millimeter-wave radar relative to the target by using the radar distance and Doppler velocity of the target detected by each receiving antenna, and detecting the target by using the horizontal angle and pitch angle includes: For the Doppler velocity and radar distance of the target detected by each receiving antenna, obtain candidate peaks of the target detected by each receiving antenna, where the peak includes the energy intensity of the target detected by the receiving antenna and the phase of the receiving antenna; Determine the candidate peak with the maximum energy intensity as the peak of the receiving antenna; Obtain the horizontal angle and pitch angle of the millimeter-wave radar relative to the target by using the peak.

7. The target detection method according to claim 6, characterized in that, The step of obtaining the horizontal angle and pitch angle of the millimeter-wave radar relative to the target by using the peak includes: Perform a third Fourier transform on the peak to obtain an angle determination parameter of the candidate horizontal angle of the target detected by the receiving antenna; Determine whether there is an angle ambiguity in the energy intensity according to the angle determination parameter; In response to the energy intensity having no angle ambiguity, obtain the horizontal angle and pitch angle of the millimeter-wave radar relative to the target by using the energy intensity.

8. The object detection method according to claim 7, wherein, The angle determination parameter is a complex number with a real part and an imaginary part. The step of determining whether there is an angle ambiguity in the energy intensity according to the angle determination parameter includes: Determine whether the sum of the squares of the real part and the imaginary part of the angle determination parameter is within a preset range; If so, there is an angle ambiguity in the energy intensity corresponding to the angle determination parameter; If not, there is no angle ambiguity in the energy intensity corresponding to the angle determination parameter.

9. The object detection method according to claim 8, wherein, The step of obtaining the horizontal angle and the pitch angle of the millimeter-wave radar relative to the target by using the energy intensity includes: obtaining the horizontal angle by using the imaginary part of the complex number, and obtaining the pitch angle by using the imaginary part and the real part of the complex number.

10. The object detection method according to claim 3, wherein, The step of performing two-dimensional Fourier transform on the sampling signals of the receiving antennas to obtain the radar distance and the Doppler velocity at which the receiving antennas detect the target further includes: determining the distance between the target and the millimeter-wave radar and the moving speed by using the radar distance and the Doppler velocity.

11. The object detection method according to claim 10, wherein, The step of determining the distance between the target and the millimeter-wave radar and the moving speed by using the radar distance and the Doppler velocity includes: obtaining the distance by using the radar distance and the distance resolution of the millimeter-wave radar, and determining the moving speed by using the Doppler velocity and the velocity resolution of the millimeter-wave radar.

12. The object detection method according to claim 3, wherein, The step of the four transmitting antennas of the millimeter-wave radar synchronously transmitting transmitted signals of frequency-modulated continuous waves with phases sequentially spaced 45 degrees includes: controlling the four transmitting antennas to synchronously transmit transmitted signals of frequency-modulated continuous waves with phases sequentially spaced 45 degrees through the first chip of the main radar; The step of synchronously receiving the received signals returned after detecting the target by using the four first receiving antennas and the four second receiving antennas of the millimeter-wave radar includes: controlling the four first receiving antennas and the four second receiving antennas to synchronously receive the received signals through the first chip and the second chip.

13. The object detection method according to claim 3, wherein, The step of sampling the received signal of each receiving antenna to obtain a sampling signal includes: performing quadrature modulation on the received signal received by each receiving antenna; mixing the modulated received signal with the transmitted signal of the corresponding transmitting antenna to obtain a mixed signal; sampling the mixed signal to obtain the sampling signal.

14. The object detection method according to claim 3, wherein, The step of detecting the target by using the horizontal angle and the pitch angle includes: tracking the target based on the horizontal angle and the pitch angle.

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