A millimeter wave radar calibration method

Abstract

The present invention belongs to the field of radar calibration technology and relates to a millimeter-wave radar calibration method. The method comprises: placing a 0° initial angle reflector in a darkroom to calibrate the radar antenna; determining the preliminary calibration coefficients of each radar antenna array element; placing at least two correction angle reflectors with angles different from the initial angle reflector; performing SVD decomposition to obtain a rotation matrix; using the rotation matrix to correct the preliminary calibration coefficients to obtain calibration coefficients for each group of radar antennas; and using the calibration coefficients for each group of antennas to calibrate each radar antenna separately. The present invention first performs radar calibration, then uses angle reflectors different from the initial angle to correct the radar calibration coefficients, thereby ensuring that the calibration directions of all radar antennas are consistent. This solves the problems existing in darkroom calibration of composite antenna radars, while providing accurate corrections without the need for outdoor calibration or a large darkroom, saving manpower and darkroom costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of radar calibration, and in particular relates to a millimeter wave radar calibration method. Background Art

[0002] With the development of millimeter-wave radar, radar antenna arrays have become increasingly complex. Radar antenna arrays often utilize multiple antenna groups in a composite configuration, for example, combining wide-beam short-range antennas with narrow-beam long-range antennas to achieve long detection ranges and minimized blind spots at close ranges. In this case, because the equivalent center positions of different antenna groups within the composite antenna vary, the discrepancies in center position are significant during calibration in a short-range anechoic chamber. This can lead to deviations in the calibrated angles, resulting in excessive horizontal deviations at long distances. Therefore, a calibration method must be used to correct for these deviations.

[0003] Phased array radars rely on the coordinated operation of multiple antenna elements. Phase and amplitude errors in each element can lead to beam pointing errors or distortion. Due to manufacturing issues, different radars have varying errors in each element. To ensure system measurement accuracy, reliability, and safety, radars must be calibrated before use to ensure consistent phase and amplitude across each element.

[0004] For a typical radar with a single antenna, simply place an angled reflector in a darkroom and position the radar at a relative 0° angle. Algorithms can then align all radar elements toward the angled reflector to achieve calibration. However, with the advancement of radar, more than one antenna set is often required for monitoring. For example, a radar might use both a wide-beam, short-range antenna and a narrow-beam, long-range antenna to achieve a long detection range with a small blind spot near the target. In this case, the two antenna sets must be tested separately. Furthermore, the darkrooms used for radar calibration are generally small, resulting in significant spacing between the two antenna sets. This ultimately leads to calibration errors between the two antenna sets, with the two antenna sets not aligning in the same direction.

[0005] The common solutions to this problem are:

[0006] (1) Calibrate the two antennas separately. This method is difficult to implement and requires placing angle reflectors at 0° for the two antennas. If the placement is not accurate, there will still be deviations.

[0007] (2) After calibration, one of the antennas is angle-compensated based on the deviation in actual use. This method requires testing and adjusting each radar after calibration, which is time-consuming and labor-intensive.

[0008] (3) Geometric correction of the antenna, that is, manually calculating the possible deviation and compensating it according to the current placement angle. This method is limited to calibration in the same environment, and any inconsistency will still cause deviation. Summary of the Invention

[0009] In order to solve the above technical problems, the present invention provides a millimeter wave radar calibration method, comprising:

[0010] Place a 0° initial angle reflector in a darkroom, calibrate the radar antenna, and obtain the coordinate expression of the calibrated initial angle reflector;

[0011] Determine the preliminary calibration coefficient of each radar antenna element based on the amplitude and phase data of each radar antenna element;

[0012] placing at least two modified angle reflectors with angles different from the initial angle reflector within the beam range of each radar antenna, measuring the angle of each radar antenna, and determining coordinate expressions for each modified angle reflector in a coordinate system with each radar antenna as the origin;

[0013] Perform SVD decomposition on the coordinate expressions of the calibrated initial angle reflector and each corrected angle reflector to obtain a rotation matrix;

[0014] The initial calibration coefficients are corrected using the rotation matrix to obtain the calibration coefficients of each group of radar antennas;

[0015] Each radar antenna is calibrated separately using the calibration coefficients of each group of antennas.

[0016] On the basis of the above technical solution, the present invention can also be improved as follows.

[0017] Furthermore, preliminary calibration coefficients of the radar antenna elements are determined based on the amplitude and phase data of the radar antenna elements, including performing conjugate processing and amplitude normalization processing on the amplitude and phase data to obtain preliminary calibration coefficients of the radar antenna elements.

[0018] Furthermore, the amplitude and phase data are conjugated and normalized to obtain preliminary calibration coefficients, including:

[0019] set up is the initial calibration coefficient, is the amplitude and phase data of the radar antenna array element, Indicates taking the absolute value, Indicates taking the maximum value, represents the conjugate transpose of the matrix, then:

[0020] .

[0021] Furthermore, there is a distance greater than two distance units between each modified angle reflector and the initial angle reflector.

[0022] Furthermore, at least two corrected angle reflectors with angles different from the initial angle reflector are placed within the beam range of each radar antenna, and the angles of each radar antenna are measured respectively, and the coordinate expressions of each corrected angle reflector in a coordinate system with each radar antenna as the origin are determined, including: the corrected angle reflector includes a first angle reflector and a second angle reflector, the coordinate system where one group of radar antennas is located is set as the first coordinate system, the coordinate system where the other group of radar antennas is located is set as the second coordinate system, and the horizontal coordinate of the first angle reflector in the first coordinate system is set as , the vertical coordinate of the first angle reflector in the first coordinate system is , the horizontal coordinate of the second angle reflector in the first coordinate system is , the vertical coordinate of the second angle reflector in the first coordinate system is , the horizontal coordinate of the first angle reflector in the second coordinate system is , the vertical coordinate of the first angle reflector in the second coordinate system is , the horizontal coordinate of the second angle reflector in the second coordinate system is , the vertical coordinate of the second angle reflector in the second coordinate system is , measure the angle of each radar antenna separately, and get the coordinate expression of the corrected angle reflector in the first coordinate system: , the coordinate expression of the corrected angle reflector in the second coordinate system is .

[0023] Furthermore, let the horizontal coordinate of the initial angle reflector in the first coordinate system be , the initial angle reflector's vertical coordinate in the first coordinate system is , the horizontal coordinate of the initial angle reflector in the second coordinate system is , the vertical coordinate of the initial angle reflector in the second coordinate system is , suppose the initial angle reflector, the first angle reflector and the second angle reflector in the first coordinate system are grouped according to the coordinate system and expressed as The initial angle reflector, the first angle reflector and the second angle reflector in the second coordinate system are grouped according to the coordinate system and expressed as , then the initial angle reflector, the first angle reflector and the second angle reflector are grouped according to the coordinate system to obtain:

[0024] ;

[0025] .

[0026] Furthermore, before performing SVD decomposition on the coordinate expressions of the calibrated initial angle reflector and the coordinate expressions of each corrected angle reflector, the initial angle reflector, the first corrected angle reflector, and the second corrected angle reflector are subjected to centroid calculation and decentralization, including: assuming that the coordinate system where one group of radar antennas is located is the first coordinate system, and the coordinate system where the other group of radar antennas is located is the second coordinate system, and the initial angle reflector, the first angle reflector, and the second angle reflector in the first coordinate system are grouped and expressed according to the coordinate system as follows: The initial angle reflector, the first angle reflector and the second angle reflector in the second coordinate system are grouped according to the coordinate system and expressed as , let the centroid calculation results of the initial angle reflector, the first modified angle reflector and the second modified angle reflector in the first coordinate system be expressed as , The center of mass calculation results of the initial angle reflector, the first corrected angle reflector and the second corrected angle reflector in the second coordinate system are expressed as follows: , The coordinates of the initial angle reflector, the first corrected angle reflector and the second corrected angle reflector in the second coordinate system are averaged to obtain the value; let the data decentralization result of the initial angle reflector, the first corrected angle reflector and the second corrected angle reflector in the first coordinate system be expressed as The data decentralization results of the initial angle reflector, the first modified angle reflector, and the second modified angle reflector in the second coordinate system are expressed as ,but:

[0027] ;

[0028] ;

[0029] set up For decentralized and The covariance matrix of To represent the transpose of the matrix, then:

[0030] .

[0031] Furthermore, the coordinate expressions of the calibrated initial angle reflector and the coordinate expressions of each corrected angle reflector are subjected to SVD decomposition, including: assuming that the coordinate system where one group of radar antennas is located is the first coordinate system, and the coordinate system where the other group of radar antennas is located is the second coordinate system, and the initial angle reflector, the first angle reflector, and the second angle reflector in the first coordinate system are grouped according to the coordinate system and expressed as follows: The initial angle reflector, the first angle reflector and the second angle reflector in the second coordinate system are grouped according to the coordinate system and expressed as , let the centroid calculation results of the initial angle reflector, the first modified angle reflector and the second modified angle reflector in the first coordinate system be expressed as , The center of mass calculation results of the initial angle reflector, the first corrected angle reflector and the second corrected angle reflector in the second coordinate system are expressed as follows: , The coordinates of the initial angle reflector, the first modified angle reflector and the second modified angle reflector in the second coordinate system are averaged to obtain the value; let the SVD decomposition function be expressed as , is a left singular matrix, is the singular value matrix, is a right singular matrix, is the rotation matrix, is the translation vector, represents the transpose of the matrix, then:

[0032] ;

[0033] ;

[0034] .

[0035] Furthermore, the rotation matrix is ​​used to correct the preliminary calibration coefficients to obtain the calibration coefficients of each group of radar antennas, including: is the rotation matrix, is the translation vector, is the angle between the actual pointing directions of the two sets of radar antennas, is the correction coefficient, is the radar antenna equivalent array, is the wavelength, is the initial calibration coefficient, is a set of radar antenna calibration coefficients, is another set of radar antenna calibration coefficients, .* represents the element-by-element multiplication operation, then:

[0036] ;

[0037] ;

[0038] Let the calibration coefficients of a set of radar antennas be the preliminary calibration coefficients, and use the rotation matrix to transform the preliminary calibration coefficients Make corrections to obtain the calibration coefficients of the corrected radar antenna:

[0039] ;

[0040] ;

[0041] Each radar antenna is corrected respectively using the corrected radar antenna calibration coefficient.

[0042] Furthermore, SVD decomposition is performed on the coordinate expression of the calibrated initial angle reflector and the coordinate expression of each corrected angle reflector to obtain a translation vector, and the spacing between the radar antennas is determined according to the translation vector.

[0043] The beneficial effects of the present invention are as follows: the present invention first performs preliminary calibration of the radar, calibrates one group of antennas, and then uses angle reflectors different from the initial angles to correct the calibration coefficients of other radar antennas, so that the calibration directions of all radar antennas are consistent, solving the problems existing in the darkroom calibration of composite antenna radars. While the correction is accurate, no outdoor calibration and no large darkroom are required, saving manpower and darkroom costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a simulation diagram of the FMCW signal sequence;

[0045] Figure 2 Schematic diagram of the angle measurement principle;

[0046] Figure 3 Schematic diagram of the angle deviation principle;

[0047] Figure 4 A schematic diagram of a millimeter-wave radar calibration method provided by the present invention;

[0048] Figure 5 Schematic diagram of the corrected radar beam pointing.

[0049] Icon: A-first set of radar antennas; B-second set of radar antennas; C-initial angle reflector. DETAILED DESCRIPTION

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0051] Millimeter wave radar transmits multiple cycles of frequency modulation continuous wave (FMCW) signals, each frequency sweep cycle is , can simultaneously measure the distance and radial velocity of each target in a multi-target scene, the emitted waveform is as shown in the attached Figure 1 shown.

[0052] The transmitted signal is reflected by the target to obtain an echo signal. After the echo signal is mixed with the transmitted signal, the range difference frequency signal frequency and Doppler frequency are obtained through two-dimensional FFT processing to calculate the target range and target speed.

[0053] Assume that the frequency of the distance difference signal is , the Doppler frequency is , the target distance is , the target speed is , is the speed of light, is the repetition cycle, is the signal bandwidth, represents the wavelength, then the target distance and target speed are expressed as:

[0054] ;

[0055] .

[0056] In order to locate the target's exact position, the target angle is detected based on the data of all radar antenna arrays. There is a path difference between the signals incident on two adjacent radar antenna elements caused by the distance. Let the path difference be The difference in wavelength causes a time delay between the signals received by two adjacent array elements. , from which the angle of the target can be obtained. Figure 2 The angle measurement principle diagram is shown in the figure. Assume that the total number of radar antenna arrays is , the horizontal coordinates of the radar antenna array from left to right are 、 、 、…… , is the distance between two adjacent radar antenna elements.

[0057] Phased array radars rely on the coordinated operation of multiple antenna elements. Phase and amplitude errors in each element can lead to beam pointing errors or distortion. Due to processing issues, different radars have different errors in each element. To ensure the system's measurement accuracy, reliability, and safety, the radar needs to be calibrated before use to keep the phase and amplitude of each element relatively consistent. For ordinary single-antenna radars, simply place an initial angle reflector in a darkroom and position the radar relative to 0°. The algorithm can then point all radar elements toward the initial angle reflector to achieve the purpose of calibration. However, with the development of radar, it is often necessary to use more than one set of antennas for monitoring. For example, a radar can use both a wide-beam short-range antenna and a narrow-beam long-range antenna to achieve a long detection range with a small blind spot at close range. In this case, the two sets of radar antennas need to be tested separately. At the same time, the darkroom area used for radar calibration is generally small, resulting in a large gap between the two sets of radar antennas. Ultimately, the calibration of the two sets of radar antennas may deviate and result in them not being in the same direction. As shown in the attached figure, Figure 3 The schematic diagram of the angle deviation principle is shown in the figure. A is the first set of radar antennas, B is the second set of radar antennas, and C is the initial angle reflector. The angle between the two radar antennas after calibration. Although both radar antennas are calibrated toward the same angle reflector, they are actually calibrated in different directions. The maximum distance from the angle reflector to the radar antenna in the anechoic chamber is typically 3-5 meters. With a spacing of 0.03 meters between the radar antennas, the error between the two radar antennas can reach 0.8°. At a distance of 100 meters, this error can reach 1.3 meters. The greater the spacing between the radar antennas, the greater the error.

[0058] In order to solve the above technical problems, the attached Figure 4 As shown, this embodiment provides a millimeter wave radar calibration method, including:

[0059] Place a 0° initial angle reflector in a darkroom, calibrate the radar antenna, and obtain the coordinate expression of the calibrated initial angle reflector;

[0060] Determine the preliminary calibration coefficient of each radar antenna element based on the amplitude and phase data of each radar antenna element;

[0061] placing at least two modified angle reflectors with angles different from the initial angle reflector within the beam range of each radar antenna, measuring the angle of each radar antenna, and determining coordinate expressions for each modified angle reflector in a coordinate system with each radar antenna as the origin;

[0062] Perform SVD decomposition on the coordinate expressions of the calibrated initial angle reflector and each corrected angle reflector to obtain a rotation matrix;

[0063] The initial calibration coefficients are corrected using the rotation matrix to obtain the calibration coefficients of each group of radar antennas;

[0064] Each radar antenna is calibrated separately using the calibration coefficients of each group of antennas.

[0065] Optionally, preliminary calibration coefficients of each radar antenna element are determined based on the amplitude and phase data of each radar antenna element, including: performing conjugate processing and amplitude normalization processing on the amplitude and phase data to obtain the preliminary calibration coefficients of each radar antenna element.

[0066] Optionally, conjugate and normalize the amplitude and phase data to obtain preliminary calibration coefficients, including:

[0067] set up is the initial calibration coefficient, is the amplitude and phase data of the radar antenna array element, Indicates taking the absolute value, Indicates taking the maximum value, represents the conjugate transpose of the matrix, then:

[0068] .

[0069] Optionally, there is a distance greater than two distance units between each corrected angle reflector and the initial angle reflector.

[0070] Optionally, at least two corrected angle reflectors with angles different from the initial angle reflector are placed within the beam range of each radar antenna, and the angles of each radar antenna are measured respectively, and the coordinate expressions of each corrected angle reflector in the coordinate system with each radar antenna as the origin are determined, including: the corrected angle reflector includes a first angle reflector and a second angle reflector, the coordinate system where one group of radar antennas is located is set as the first coordinate system, the coordinate system where the other group of radar antennas is located is set as the second coordinate system, and the horizontal coordinate of the first angle reflector in the first coordinate system is set as , the vertical coordinate of the first angle reflector in the first coordinate system is , the horizontal coordinate of the second angle reflector in the first coordinate system is , the vertical coordinate of the second angle reflector in the first coordinate system is , the horizontal coordinate of the first angle reflector in the second coordinate system is , the vertical coordinate of the first angle reflector in the second coordinate system is , the horizontal coordinate of the second angle reflector in the second coordinate system is , the vertical coordinate of the second angle reflector in the second coordinate system is , measure the angle of each radar antenna separately, and get the coordinate expression of the corrected angle reflector in the first coordinate system: , the coordinate expression of the corrected angle reflector in the second coordinate system is .

[0071] SVD (Matrix Singular Value Decomposition) is performed using three sets of data: the initial calibrated angle reflector, the coordinates of the first angle reflector, and the coordinates of the second angle reflector. In practice, increasing the number of angle reflectors used for correction can yield more accurate results. Generally, using three sets of data is sufficient to achieve good correction results.

[0072] Optionally, let the horizontal coordinate of the initial angle reflector in the first coordinate system be , the initial angle reflector's vertical coordinate in the first coordinate system is , the horizontal coordinate of the initial angle reflector in the second coordinate system is , the vertical coordinate of the initial angle reflector in the second coordinate system is , suppose the initial angle reflector, the first angle reflector and the second angle reflector in the first coordinate system are grouped according to the coordinate system and expressed as The initial angle reflector, the first angle reflector and the second angle reflector in the second coordinate system are grouped according to the coordinate system and expressed as , then the initial angle reflector, the first angle reflector and the second angle reflector are grouped according to the coordinate system to obtain:

[0073] ;

[0074] .

[0075] Optionally, before performing SVD decomposition on the coordinate expressions of the calibrated initial angle reflector and the coordinate expressions of each corrected angle reflector, the centroid of the initial angle reflector, the first corrected angle reflector, and the second corrected angle reflector are calculated and decentralized, including: assuming that the centroid calculation results of the initial angle reflector, the first corrected angle reflector, and the second corrected angle reflector in the first coordinate system are expressed as , The center of mass calculation results of the initial angle reflector, the first corrected angle reflector and the second corrected angle reflector in the second coordinate system are expressed as follows: , The coordinates of the initial angle reflector, the first corrected angle reflector and the second corrected angle reflector in the second coordinate system are averaged to obtain the value; let the data decentralization result of the initial angle reflector, the first corrected angle reflector and the second corrected angle reflector in the first coordinate system be expressed as The data decentralization results of the initial angle reflector, the first modified angle reflector, and the second modified angle reflector in the second coordinate system are expressed as ,but:

[0076] ;

[0077] ;

[0078] set up For decentralized and The covariance matrix of To represent the transpose of the matrix, then:

[0079] .

[0080] Optionally, the coordinate expression of the calibrated initial angle reflector and the coordinate expression of each corrected angle reflector are subjected to SVD decomposition, including: assuming that the coordinate system where one group of radar antennas is located is a first coordinate system, and the coordinate system where the other group of radar antennas is located is a second coordinate system, and the initial angle reflector, the first angle reflector, and the second angle reflector in the first coordinate system are grouped according to the coordinate system and expressed as follows: The initial angle reflector, the first angle reflector and the second angle reflector in the second coordinate system are grouped according to the coordinate system and expressed as , let the centroid calculation results of the initial angle reflector, the first modified angle reflector and the second modified angle reflector in the first coordinate system be expressed as , The center of mass calculation results of the initial angle reflector, the first corrected angle reflector and the second corrected angle reflector in the second coordinate system are expressed as follows: , The coordinates of the initial angle reflector, the first modified angle reflector and the second modified angle reflector in the second coordinate system are averaged to obtain the value; let the SVD decomposition function be expressed as , is a left singular matrix, is the singular value matrix, is a right singular matrix, is the rotation matrix, is the translation vector, represents the transpose of the matrix, then:

[0081] ;

[0082] ;

[0083] .

[0084] Optionally, the calibration coefficients of each group of radar antennas are obtained by correcting the initial calibration coefficients using the rotation matrix, including: is the rotation matrix, is the translation vector, is the angle between the actual pointing directions of the two sets of radar antennas, is the correction coefficient, is the radar antenna equivalent array, is the wavelength, is the initial calibration coefficient, is a set of radar antenna calibration coefficients, is another set of radar antenna calibration coefficients, .* represents the element-by-element multiplication operation, then:

[0085] ;

[0086] ;

[0087] Let the calibration coefficients of a set of radar antennas be the preliminary calibration coefficients, and use the rotation matrix to transform the preliminary calibration coefficients Make corrections to obtain the calibration coefficients of the corrected radar antenna:

[0088] ;

[0089] ;

[0090] Each radar antenna is corrected respectively using the corrected radar antenna calibration coefficient.

[0091] At this time, although the two sets of radar antennas are not pointing to 0°, they are pointing to the same position. That is, there is no deviation between the two sets of radar antennas. Figure 5 The diagram of the corrected radar beam pointing is shown in Figure 1. A is the equivalent position of the first group of radar antennas, B is the equivalent position of the second group of radar antennas, the arrows indicate the corrected beam pointing, C is the initial angle reflector, and the attached Figure 5 The results show that the antennas of each group are pointing relative to each other after calibration using the corrected calibration coefficients. Figure 3 changes.

[0092] The present invention first performs a preliminary radar calibration, calibrating one antenna group (the reference antenna). It then uses angle reflectors with different angles than the initial one to correct the calibration coefficients of the remaining radar antennas, thereby aligning the calibration directions of all radar antennas. If the radar has multiple antenna groups, all antennas except the reference antenna can be directly calibrated against the reference antenna to complete the overall calibration. This invention solves the problems associated with darkroom calibration of composite antenna radars, providing accurate corrections without the need for outdoor calibration or a large darkroom, saving both labor and darkroom costs.

[0093] Optionally, SVD decomposition can be performed on the coordinate expressions of the calibrated initial angle reflector and the coordinate expressions of each corrected angle reflector to obtain a translation vector, which is used to determine the spacing between the radar antennas. The final radar detection result can then be horizontally corrected based on the spacing between the two sets of radar antennas.

[0094] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A millimeter wave radar calibration method, characterized in that: include: Place a 0° initial angle reflector in a darkroom, calibrate the radar antenna, and obtain the coordinate expression of the calibrated initial angle reflector; Determine the preliminary calibration coefficient of each radar antenna element based on the amplitude and phase data of each radar antenna element; placing at least two modified angle reflectors with angles different from the initial angle reflector within the beam range of each radar antenna, measuring the angle of each radar antenna, and determining coordinate expressions for each modified angle reflector in a coordinate system with each radar antenna as the origin; Perform SVD decomposition on the coordinate expressions of the calibrated initial angle reflector and each corrected angle reflector to obtain a rotation matrix; Using the rotation matrix to correct the preliminary calibration coefficients, the calibration coefficients of each group of radar antennas are obtained, including using the rotation matrix to correct the preliminary calibration coefficients, the calibration coefficients of each group of radar antennas are obtained, including: setting is the rotation matrix, is the translation vector, is the angle between the actual pointing directions of the two sets of radar antennas, is the correction coefficient, is the radar antenna equivalent array, is the wavelength, is the initial calibration coefficient, is a set of radar antenna calibration coefficients, is another set of radar antenna calibration coefficients, .* represents the element-by-element multiplication operation, then: ; ; Let the calibration coefficients of a set of radar antennas be the preliminary calibration coefficients, and use the rotation matrix to transform the preliminary calibration coefficients Make corrections to obtain the calibration coefficients of the corrected radar antenna: ； ； Using the corrected radar antenna calibration coefficients, each radar antenna is corrected separately; Each radar antenna is calibrated separately using the calibration coefficients of each group of antennas.

2. A millimeter wave radar calibration method according to claim 1, characterized in that: According to the amplitude and phase data of each radar antenna array element, the preliminary calibration coefficient of each radar antenna array element is determined, including: performing conjugate processing and amplitude normalization processing on the amplitude and phase data to obtain the preliminary calibration coefficient of each radar antenna array element.

3. The millimeter wave radar calibration method according to claim 2, characterized in that: Perform conjugate processing and amplitude normalization on the amplitude and phase data to obtain preliminary calibration coefficients, including: set up is the initial calibration coefficient, is the amplitude and phase data of the radar antenna array element, Indicates taking the absolute value, Indicates taking the maximum value, represents the conjugate transpose of the matrix, then: 。 4. The millimeter wave radar calibration method according to claim 1, characterized in that: There is a distance greater than two distance units between each modified angle reflector and the initial angle reflector.

5. The millimeter wave radar calibration method according to claim 1, characterized in that: At least two modified angle reflectors with angles different from the initial angle reflector are placed within the beam range of each radar antenna, and the angles of each radar antenna are measured respectively, and the coordinate expressions of each modified angle reflector in the coordinate system with each radar antenna as the origin are determined, including: the modified angle reflector includes a first angle reflector and a second angle reflector, the coordinate system where one group of radar antennas is located is set as the first coordinate system, the coordinate system where the other group of radar antennas is located is set as the second coordinate system, and the horizontal coordinate of the first angle reflector in the first coordinate system is set as , the vertical coordinate of the first angle reflector in the first coordinate system is , the horizontal coordinate of the second angle reflector in the first coordinate system is , the vertical coordinate of the second angle reflector in the first coordinate system is , the horizontal coordinate of the first angle reflector in the second coordinate system is , the vertical coordinate of the first angle reflector in the second coordinate system is , the horizontal coordinate of the second angle reflector in the second coordinate system is , the vertical coordinate of the second angle reflector in the second coordinate system is , measure the angle of each radar antenna separately, and get the coordinate expression of the corrected angle reflector in the first coordinate system: , the coordinate expression of the corrected angle reflector in the second coordinate system is .

6. A millimeter wave radar calibration method according to claim 5, characterized in that: Assume that the horizontal coordinate of the initial angle reflector in the first coordinate system is , the initial angle reflector's vertical coordinate in the first coordinate system is , the horizontal coordinate of the initial angle reflector in the second coordinate system is , the vertical coordinate of the initial angle reflector in the second coordinate system is , suppose the initial angle reflector, the first angle reflector and the second angle reflector in the first coordinate system are grouped according to the coordinate system and expressed as The initial angle reflector, the first angle reflector and the second angle reflector in the second coordinate system are grouped according to the coordinate system and expressed as , then the initial angle reflector, the first angle reflector and the second angle reflector are grouped according to the coordinate system to obtain: ； 。 7. The millimeter wave radar calibration method according to claim 1, characterized in that: Before performing SVD decomposition on the coordinate expressions of the calibrated initial angle reflector and the coordinate expressions of each corrected angle reflector, the centroid of the initial angle reflector, the first corrected angle reflector, and the second corrected angle reflector are calculated and decentralized, including: assuming that the coordinate system where one group of radar antennas is located is the first coordinate system, and the coordinate system where the other group of radar antennas is located is the second coordinate system, the initial angle reflector, the first angle reflector, and the second angle reflector in the first coordinate system are grouped and expressed according to the coordinate system as follows: The initial angle reflector, the first angle reflector and the second angle reflector in the second coordinate system are grouped according to the coordinate system and expressed as , let the centroid calculation results of the initial angle reflector, the first modified angle reflector and the second modified angle reflector in the first coordinate system be expressed as , The center of mass calculation results of the initial angle reflector, the first corrected angle reflector and the second corrected angle reflector in the second coordinate system are expressed as follows: , The coordinates of the initial angle reflector, the first corrected angle reflector and the second corrected angle reflector in the second coordinate system are averaged to obtain the value; let the data decentralization result of the initial angle reflector, the first corrected angle reflector and the second corrected angle reflector in the first coordinate system be expressed as The data decentralization results of the initial angle reflector, the first modified angle reflector, and the second modified angle reflector in the second coordinate system are expressed as ,but: ； ； set up For decentralized and The covariance matrix of To represent the transpose of the matrix, then: 。 8. A millimeter wave radar calibration method according to claim 7, characterized in that: The coordinate expressions of the calibrated initial angle reflector and the coordinate expressions of each corrected angle reflector are subjected to SVD decomposition, including: assuming that the coordinate system where one group of radar antennas is located is the first coordinate system, and the coordinate system where the other group of radar antennas is located is the second coordinate system, and the initial angle reflector, the first angle reflector, and the second angle reflector in the first coordinate system are grouped and expressed according to the coordinate system as follows: The initial angle reflector, the first angle reflector and the second angle reflector in the second coordinate system are grouped according to the coordinate system and expressed as , let the centroid calculation results of the initial angle reflector, the first modified angle reflector and the second modified angle reflector in the first coordinate system be expressed as , The center of mass calculation results of the initial angle reflector, the first corrected angle reflector and the second corrected angle reflector in the second coordinate system are expressed as follows: , The coordinates of the initial angle reflector, the first modified angle reflector and the second modified angle reflector in the second coordinate system are averaged to obtain the value; let the SVD decomposition function be expressed as , is a left singular matrix, is the singular value matrix, is a right singular matrix, is the rotation matrix, is the translation vector, represents the transpose of the matrix, then: ； ； 。 9. The millimeter wave radar calibration method according to claim 1, characterized in that: The coordinate expressions of the calibrated initial angle reflector and the coordinate expressions of each corrected angle reflector are subjected to SVD decomposition to obtain translation vectors, and the spacing between radar antennas is determined according to the translation vectors.

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