阅读说明：本技术 一种新型毫米波雷达信号处理方法 (Novel millimeter wave radar signal processing method ) 是由 金烨 安清儒 刘建虎 陈桥 梁思嘉 常维国 王瑜琪 龙佳敏 连红飞 陈思佳 李乐 于 2020-11-13 设计创作，主要内容包括：本公开的雷达信号处理方法,布局毫米波雷达虚拟天线阵列,当方位角大于虚拟天线的测量方位角时,实际相位差与测量相位差存在周期偏差；测量相位差,根据相位法测角原理计算模糊方位角；将模糊方位角代入俯仰补偿相位差公式得到俯仰补偿相位差,利用俯仰补偿相位差对天线阵元补偿后根据相位法测角原理得到俯仰角；将俯仰角代入俯仰补偿相位差公式得到方向维俯仰补偿相位差,利用方向维俯仰补偿相位差对天线阵元进行相位补偿后根据相位法测角原理得到不模糊方位角；比较模糊方位角和不模糊方位角,当两者相等时得到俯仰角的真实值。能够无需额外增加天线数量情况下,实现较大的FOV和较高的角度分辨率,有效调和角度分辨率和方位角范围的矛盾。(According to the radar signal processing method, the millimeter wave radar virtual antenna array is distributed, and when the azimuth angle is larger than the measurement azimuth angle of the virtual antenna, the actual phase difference and the measurement phase difference have periodic deviation; measuring the phase difference, and calculating a fuzzy azimuth angle according to a phase method angle measurement principle; substituting the fuzzy azimuth angle into a pitching compensation phase difference formula to obtain a pitching compensation phase difference, compensating the antenna array element by using the pitching compensation phase difference, and then obtaining a pitching angle according to a phase method angle measurement principle; substituting the pitch angle into a pitch compensation phase difference formula to obtain a direction dimension pitch compensation phase difference, performing phase compensation on the antenna array element by using the direction dimension pitch compensation phase difference, and obtaining an unambiguous azimuth angle according to a phase method angle measurement principle; and comparing the fuzzy azimuth angle with the non-fuzzy azimuth angle, and obtaining the true value of the pitch angle when the fuzzy azimuth angle and the non-fuzzy azimuth angle are equal. Under the condition of not additionally increasing the number of the antennas, a larger FOV and a higher angular resolution can be realized, and the contradiction between the angular resolution and the azimuth angle range can be effectively reconciled.)

1. A novel millimeter wave radar signal processing method is characterized by comprising the following steps:

distributing a millimeter wave radar array based on an FMCW signal model to obtain a millimeter wave radar virtual antenna array corresponding to the millimeter wave radar array, wherein when an azimuth angle of a measured target is larger than the range of a measurement azimuth angle of the millimeter wave radar virtual antenna, n period deviations exist between the actual phase difference and the measurement phase difference of the measured target, and n is a positive integer;

measuring the phase difference of a millimeter wave radar virtual antenna array, calculating the fuzzy azimuth angle of the measured target according to the virtual antenna array element spacing d and the phase difference angle measurement principle of the measured phase difference, and traversing n values to obtain a group of fuzzy azimuth angles of the measured target;

substituting the group of fuzzy azimuth angles into a pitching compensation phase difference formula to obtain a group of pitching compensation phase differences, and utilizing the group of pitching compensation phase differences to obtain a pitching distance d_pAfter compensating the virtual antenna array element, compensating the virtual antenna array element according to the group of pitching compensation phase differences and the pitching distance d_pCalculating to obtain a group of pitch angles of the measured target according to the phase difference angle measurement principle;

substituting a group of pitch angles into a pitch compensation phase difference formula to obtain a group of direction dimension pitch compensation phase differences, and utilizing the group of direction dimension pitch compensation phase differences to obtain a distance d between the direction dimension antenna array elements₃And the pitch antenna interval is d_pAfter the virtual antenna array element carries out phase compensation, according to the group of direction dimension pitching compensation phase differences and the direction dimension antenna array element spacing d₃The phase difference angle measurement principle of (1) calculates a set of unambiguous azimuth angles of the measured object, wherein d₃<d；

And comparing the fuzzy azimuth angle and the non-fuzzy azimuth angle of the measured target, wherein when the fuzzy azimuth angle and the non-fuzzy azimuth angle are equal, the corresponding pitch angle is the real value of the pitch angle of the measured target, and the non-fuzzy azimuth angle is the real value of the azimuth angle of the measured target.

Technical Field

The disclosure belongs to the technical field of radars, and particularly relates to a novel millimeter wave radar signal processing method.

Background

In vehicle-mounted radar design, phase method angle measurement is generally used as a detection method of the azimuth angle of a measured target. Acquiring the phase of each echo of a measured object by using a plurality of antennae at different spatial positions, generating a phase difference due to the existence of echo wave path difference delta R (delta R ═ dsin theta), and calculating the azimuth angle of the measured object through the phase difference (according to the phase difference). Theoretically, if the phase difference of each echo is known, the azimuth angle of the measured target can be accurately calculated, however, in the measuring process, the phase difference is limited to (-pi, pi), and a plurality of periods of deviation exist between the actual value of the phase difference and the measured value, namely, the phase difference is deviated from the measured valueReferred to as phase ambiguity.

When the phase difference is betweenTake the value of + -piWhen the azimuth angle is equal to the maximum unambiguous angleThe azimuth angle is measured in the range ofThus, the smaller the antenna spacing d, the greater the angle measurement range, but the angular resolutionThe size is increased, which is not beneficial to distinguishing the measured target in the angle dimension.

From the above analysis, it can be seen that there is an irreconcilable conflict between the angular range and the angular resolution. Generally, MIMO (Multiple Input Multiple Output) technology is adopted to increase the number of virtual antennas (N)_tol＝N_RX*N_TX) To improve angular resolution. Fig. 1 shows that a set of automotive radar arrays can achieve an angular resolution of 30 °, and fig. 2 shows that when the angles of two measured targets are different by 30 °, the two targets cannot be separated in an angular dimension. The angle measuring method comprises recording beat signals corresponding to each pair of transmitting-receiving antennas, wherein N is the number of the beat signals_tolPerforming Fast Fourier Transform (FFT) on each echo signal, wherein each FFT corresponds to a virtual antenna to obtain N_tolAn amplitude-frequency characteristic matrix; then to N_tolAnd respectively performing 2D-CFAR (2D-Constant False-Alarm Rate) on the amplitude-frequency characteristic matrix corresponding to each virtual antenna, recording the position corresponding to the effective frequency point, and performing angle dimension FFT on the angle of the corresponding position to obtain the azimuth angle of the target.

Although the MIMO technology realizes the multiple increase of the number of antenna arrays, the virtual array doubles the number of receiving antennas when one transmitting antenna is added, and the angle measurement resolution is effectively improved to a certain extent, but the increase of the number of the antennas causes the increase of the volume of the radar and the increase of the cost. In addition, under the condition of limited number of antennas, the angular resolution is improved along with the increase of the antenna spacing, however, the field angle FOV is reduced, and two indexes of the angular resolution and the FOV cannot be considered simultaneously.

Disclosure of Invention

In view of this, the present disclosure provides a novel millimeter wave radar signal processing method, which can implement a larger field of view FOV and a higher angular resolution under the condition of a limited number of antennas, and can effectively reconcile the contradiction between the angular resolution and the measurement azimuth range while completing the pitch angle without additionally adding a processing algorithm, and reduce the volume and weight of the radar and reduce the cost.

According to an aspect of the present disclosure, a novel millimeter wave radar signal processing method is provided, the method including:

distributing a millimeter wave radar array based on an FMCW signal model to obtain a millimeter wave radar virtual antenna array corresponding to the millimeter wave radar array, wherein when an azimuth angle of a measured target is larger than the range of a measurement azimuth angle of the millimeter wave radar virtual antenna, n period deviations exist between the actual phase difference and the measurement phase difference of the measured target, and n is a positive integer;

measuring the phase difference of a millimeter wave radar virtual antenna array, calculating the fuzzy azimuth angle of the measured target according to the virtual antenna array element spacing d and the phase difference angle measurement principle of the measured phase difference, and traversing n values to obtain a group of fuzzy azimuth angles of the measured target;

substituting the group of fuzzy azimuth angles into a pitching compensation phase difference formula to obtain a group of pitching compensation phase differences, and utilizing the group of pitching compensation phase differences to obtain a pitching distance d_pAfter compensating the virtual antenna array element, compensating the virtual antenna array element according to the group of pitching compensation phase differences and the pitching distance d_pCalculating to obtain a group of pitch angles of the measured target according to the phase difference angle measurement principle;

substituting a group of pitch angles into a pitch compensation phase difference formula to obtain a group of direction dimension pitch compensation phase differences, and utilizing the group of direction dimension pitch compensation phase differences to obtain a distance d between the direction dimension antenna array elements₃And the pitch antenna interval is d_pAfter the virtual antenna array element carries out phase compensation, according to the group of direction dimension pitching compensation phase differences and the direction dimension antenna array element spacing d₃The phase difference angle measurement principle of (2) calculates a group of errors of the measured objectFuzzy azimuth angle, wherein d₃<d；

And comparing the fuzzy azimuth angle and the non-fuzzy azimuth angle of the measured target, wherein when the fuzzy azimuth angle and the non-fuzzy azimuth angle are equal, the corresponding pitch angle is the real value of the pitch angle of the measured target, and the non-fuzzy azimuth angle is the real value of the azimuth angle of the measured target.

According to the novel millimeter wave radar array processing method, the millimeter wave radar virtual antenna array corresponding to the millimeter wave radar array is obtained by arranging the millimeter wave radar array based on the FMCM signal model, when the azimuth angle of a target to be measured is larger than the range of the measurement azimuth angle of the millimeter wave radar virtual antenna, n periodic deviations exist between the actual phase difference and the measurement phase difference of the target to be measured, and n is a positive integer; measuring the phase difference of a millimeter wave radar virtual antenna array, calculating the fuzzy azimuth angle of the measured target according to the virtual antenna array element spacing d and the phase difference angle measurement principle of the measured phase difference, and traversing n values to obtain a group of fuzzy azimuth angles of the measured target; substituting the group of fuzzy azimuth angles into a pitching compensation phase difference formula to obtain a group of pitching compensation phase differences, and utilizing the group of pitching compensation phase differences to obtain a pitching distance d_pAfter compensating the virtual antenna array element, compensating the virtual antenna array element according to the group of pitching compensation phase differences and the pitching distance d_pCalculating to obtain a group of pitch angles of the measured target according to the phase difference angle measurement principle; substituting a group of pitch angles into a pitch compensation phase difference formula to obtain a group of direction dimension pitch compensation phase differences, and utilizing the group of direction dimension pitch compensation phase differences to obtain a distance d between the direction dimension antenna array elements₃And the pitch antenna interval is d_pAfter the virtual antenna array element carries out phase compensation, according to the group of direction dimension pitching compensation phase differences and the direction dimension antenna array element spacing d₃The phase difference angle measurement principle of (1) calculates a set of unambiguous azimuth angles of the measured object, wherein d₃<d; and comparing the fuzzy azimuth angle and the non-fuzzy azimuth angle of the measured target, wherein when the fuzzy azimuth angle and the non-fuzzy azimuth angle are equal, the corresponding pitch angle is the real value of the pitch angle of the measured target, and the non-fuzzy azimuth angle is the real value of the azimuth angle of the measured target. Can realize larger field angle FOV and higher angular resolution under the condition of limited antenna number,the method can effectively reconcile the contradiction between the angular resolution and the measurement azimuth angle range while finishing the pitch angle without additionally adding a processing algorithm, and reduces the volume and weight of the radar and the cost.

Other features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments, features, and aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.

FIG. 1 shows a schematic diagram of a millimeter wave radar array according to the prior art;

FIG. 2 is a schematic diagram showing a millimeter wave radar array measuring a measured target with a phase angle difference of 30 degrees according to the prior art;

FIG. 3 illustrates a flow diagram of a novel millimeter wave radar signal processing method in accordance with an embodiment of the present disclosure;

FIG. 4 illustrates a flow diagram of a novel millimeter wave radar signal processing method according to another embodiment of the present disclosure;

FIG. 5 shows a schematic view of a fuzzy azimuth dimensional goniometric array in accordance with another embodiment of the present disclosure;

FIG. 6 shows a schematic view of a pitch dimensional angular array according to another embodiment of the present disclosure;

FIG. 7 shows a schematic diagram of a non-ambiguous azimuthal dimension goniometric array, according to another embodiment of the present disclosure;

FIG. 8 is a schematic diagram showing a result of angle measurement with an angular resolution of 3 degrees according to another embodiment of the present disclosure;

Detailed Description

Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present disclosure. It will be understood by those skilled in the art that the present disclosure may be practiced without some of these specific details. In some instances, methods, means, elements and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present disclosure.

Fig. 3 shows a flow chart of a novel millimeter wave radar signal processing method according to an embodiment of the present disclosure. The method can be used for radar signal processing with high angle resolution, fuzzy azimuth angles, pitch angles and non-fuzzy azimuth angles are measured respectively by selecting radar echo data combinations of different channels, and time angle ambiguity resolution can be achieved while high angle resolution is guaranteed through result comparison to increase the field of view (FOV).

As shown in fig. 1, the method may include:

step S11: distributing a millimeter wave radar array based on an FMCM signal model to obtain a millimeter wave radar virtual antenna array corresponding to the millimeter wave radar array; when the azimuth angle of the measured target is larger than the range of the measurement azimuth angle of the millimeter wave radar virtual antenna, n periodic deviations exist between the actual phase difference and the measurement phase difference of the measured target, and n is a positive integer.

FMCW (Frequency Modulated Continuous Wave) may mean that the received echo Frequency is the same as the transmitted Frequency variation law, and is a triangular Wave law with time difference, and the target distance may be calculated by using the time difference.

Based on the FMCW signal model, a millimeter wave radar virtual antenna array corresponding to the millimeter wave radar array can be formed by designing the layout of special millimeter wave radar antennas.

Different antenna array elements in the virtual antenna array are respectively selected in the phase method angle measurement process, so that the unambiguous detection of the azimuth angle and the measurement of the pitch angle are realized.

Fig. 4 shows a flow diagram of a novel millimeter wave radar signal processing method according to another embodiment of the present disclosure. As shown in fig. 4, when the azimuth angle of the target to be measured is greater than the range of the measurement azimuth angle of the millimeter wave radar virtual antenna, n periodic deviations exist between the actual phase difference and the measurement phase difference of the target to be measured, n is a positive integer, and a group of fuzzy azimuth angles, a group of pitch angles, and a group of non-fuzzy azimuth angles can be obtained by traversing n values.

Step S12: and measuring the phase difference of the millimeter wave radar virtual antenna array, calculating the fuzzy azimuth angle of the measured target according to the virtual antenna array element spacing d and the phase difference angle measurement principle of measuring the phase difference, and traversing n values to obtain a group of fuzzy azimuth angles of the measured target.

FIG. 5 illustrates a schematic view of a fuzzy azimuth dimensional goniometric array in accordance with another embodiment of the present disclosure.

As shown in fig. 5, at least 3 equidistant virtual antenna elements are selected, the distance between the virtual antenna elements is d, the distance between the known virtual antenna elements is d, and the phase difference between the channels of the virtual antenna elements is measuredAccording to the principle of angle measurement by phase methodThe distance between the virtual antenna elements is d and the phase difference is measuredSubstituting into the formula for measuring angle by phase method to obtain the measured phase angle of the measured targetWhen the phase difference is betweenThen, the maximum fuzzy azimuth angle of the measured target with the virtual antenna array element spacing of d is obtained

Since when the measured object isWhen the azimuth angle is larger than the range of the measurement azimuth angle of the millimeter wave radar virtual antenna, n period deviations exist between the actual phase difference and the measurement phase difference of the measured target, and the actual azimuth angle of the measured target

Since the actual phase difference of the measured object is limited to (- π, π), sin is applied_real1 or less andsubstituting into the actual azimuth formula to obtain the maximum value of nThe range of azimuth angles of the measured target can be obtainedAnd traversing all the n values to obtain a group of fuzzy azimuth angles of the measured target, wherein the real azimuth angle of the measured target is contained in the group of fuzzy azimuth angles of the measured target.

Step S13: substituting the group of fuzzy azimuth angles into a pitching compensation phase difference formula to obtain a group of pitching compensation phase differences, and utilizing the group of pitching compensation phase differences to obtain a pitching distance d_pAfter compensating the virtual antenna array element, compensating the phase difference and the pitch distance d according to a group of pitch compensation phase differences_pThe phase difference angle measurement principle can calculate a group of pitch angles of the measured target.

Fig. 6 shows a schematic view of a pitch dimensional angular array according to another embodiment of the present disclosure.

As shown in FIG. 6, d₂For the spacing in the azimuth dimension of the virtual antennas, d_pThe pitch dimension of the virtual antenna. Selecting pitch interval as d_pTwo virtual antenna elements of pitch spacing d_pMay be determined from a pitch angle index, e.g. pitch angle resolutionAnd range of measurementWherein N is_RXFor the number of receiving antennas, N_TXThe number of virtual antennas.

Before measuring the pitch angle of the measured target, the pitch distance d needs to be adjusted_pThe virtual antenna array element carries out phase compensation to ensure that the pitch distance d_pThe virtual antenna array elements are aligned in the azimuth dimension, and a group of fuzzy azimuth angles of the measured target calculated in the step S12 are substituted into a pitching compensation phase difference formulaObtaining a group of pitching compensation phase differences, and calculating the pitching compensation phase differences and the pitching distances d_pAnd substituting the phase difference angle measurement formula to calculate a group of pitch angles of the measured target, and aligning and measuring the pitch angles by compensating the phase through the azimuth angle.

Step S14: substituting the group of pitch angles into a pitch compensation phase difference formula to obtain a group of direction dimension pitch compensation phase differences, and utilizing the group of direction dimension pitch compensation phase differences to obtain a distance d between the direction dimension antenna array elements₃And the pitch antenna interval is d_pAfter the virtual antenna array element carries out phase compensation, the phase difference is compensated according to a group of direction dimension pitching and the distance d between the direction dimension antenna array elements₃The phase difference angle measurement principle of (1) can calculate a set of unambiguous azimuth angles of the measured object, wherein d₃<d。

FIG. 7 illustrates a schematic diagram of a non-ambiguous azimuthal dimension goniometric array in accordance with another embodiment of the present disclosure.

As shown in FIG. 7, d₃Is the virtual antenna azimuth dimension spacing. Selecting two azimuth dimensions with a distance d₃And the distance in elevation dimension is d_pOf the virtual antenna element of (1), wherein d₃<d. Before measuring the unambiguous azimuth angle of the measured target, phase compensation needs to be carried out on the group of virtual antenna array elements so that the group of virtual antenna array elements are aligned in the azimuth dimension. Substituting the set of pitch angles of the measured object calculated in step S13 into the pitch compensation phase difference formulaObtaining a group of pitching compensation phase differences, and calculating the pitching compensation phase differences and the pitching distances d₃Substituting the phase difference angle measurement formula to calculate a group of unambiguous azimuth angles of the measured target, and aligning and measuring the azimuth angles by compensating the pitch angles.

Step S15: and comparing the fuzzy azimuth angle and the non-fuzzy azimuth angle of the measured target, wherein when the fuzzy azimuth angle and the non-fuzzy azimuth angle are equal, the corresponding pitch angle is the real value of the pitch angle of the measured target, and the non-fuzzy azimuth angle is the real value of the azimuth angle of the measured target.

Comparing the group of blurred azimuth angles of the measured object calculated in the step S12 with the group of unblurred azimuth angles of the measured object calculated in the step S15, when the blurred azimuth angle of the measured object is the same as the unblurred azimuth angle, the compensated phase is correct, and the corresponding unblurred azimuth angle and the pitch angle corresponding to the unblurred azimuth angle are the true values of the measured object. High angular resolution can be obtained through the large-spacing and equal-spacing virtual antenna array elements, and the pitch angle is measured by resolving ambiguity through the phase angle and increasing the field angle FOV.

Fig. 8 is a schematic diagram illustrating a result of angle measurement with an angular resolution of 3 degrees according to another embodiment of the present disclosure.

By the millimeter wave radar signal processing method, the number of antennas does not need to be additionally increased, only the virtual antenna array required by the method needs to be designed, and a larger field angle FOV and higher angular resolution can be simultaneously realized by the corresponding signal processing method.

Compared with the 30 ° angular resolution of the 3TX4RX radar shown in fig. 2, the angular resolution is improved by a factor of 10, and the resolution reaches 3 °, as shown in fig. 8. And when the same angle measurement index is met, the radar has the advantages of smaller volume, lighter weight and lower cost, and when the azimuth angle and the pitch angle are measured simultaneously, an extra processing algorithm is not needed.

The novel millimeter wave radar array processing method disclosed by the invention is used for laying out the millimeter wave radar array based on the FMCM signal model to obtain the millimeter wave radar arrayWhen the azimuth angle of a measured target is larger than the range of the measurement azimuth angle of the millimeter wave radar virtual antenna, n periodic deviations exist between the actual phase difference and the measurement phase difference of the measured target, and n is a positive integer; measuring the phase difference of a millimeter wave radar virtual antenna array, calculating the fuzzy azimuth angle of the measured target according to the virtual antenna array element spacing d and the phase difference angle measurement principle of the measured phase difference, and traversing n values to obtain a group of fuzzy azimuth angles of the measured target; substituting the group of fuzzy azimuth angles into a pitching compensation phase difference formula to obtain a group of pitching compensation phase differences, and utilizing the group of pitching compensation phase differences to obtain a pitching distance d_pAfter compensating the virtual antenna array element, compensating the virtual antenna array element according to the group of pitching compensation phase differences and the pitching distance d_pCalculating to obtain a group of pitch angles of the measured target according to the phase difference angle measurement principle; substituting a group of pitch angles into a pitch compensation phase difference formula to obtain a group of direction dimension pitch compensation phase differences, and utilizing the group of direction dimension pitch compensation phase differences to obtain a distance d between the direction dimension antenna array elements₃And the pitch antenna interval is d_pAfter the virtual antenna array element carries out phase compensation, according to the group of direction dimension pitching compensation phase differences and the direction dimension antenna array element spacing d₃The phase difference angle measurement principle of (1) calculates a set of unambiguous azimuth angles of the measured object, wherein d₃<d; and comparing the fuzzy azimuth angle and the non-fuzzy azimuth angle of the measured target, wherein when the fuzzy azimuth angle and the non-fuzzy azimuth angle are equal, the corresponding pitch angle is the real value of the pitch angle of the measured target, and the non-fuzzy azimuth angle is the real value of the azimuth angle of the measured target. Under the condition of limited number of antennas, a larger field angle FOV and a higher angular resolution can be realized, the contradiction between the angular resolution and the measurement azimuth angle range can be effectively reconciled while the pitch angle is finished without additionally increasing a processing algorithm, the volume and the weight of the radar are reduced, and the cost is reduced.

Having described embodiments of the present disclosure, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.