CN117724100A - Forward-looking imaging method and device for vehicle and double-antenna radar - Google Patents
Forward-looking imaging method and device for vehicle and double-antenna radar Download PDFInfo
- Publication number
- CN117724100A CN117724100A CN202311753640.5A CN202311753640A CN117724100A CN 117724100 A CN117724100 A CN 117724100A CN 202311753640 A CN202311753640 A CN 202311753640A CN 117724100 A CN117724100 A CN 117724100A
- Authority
- CN
- China
- Prior art keywords
- antenna
- echo
- radar
- signals
- synthetic aperture
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000003384 imaging method Methods 0.000 title claims abstract description 102
- 230000006835 compression Effects 0.000 claims abstract description 36
- 238000007906 compression Methods 0.000 claims abstract description 36
- 238000012937 correction Methods 0.000 claims abstract description 36
- 230000005012 migration Effects 0.000 claims abstract description 33
- 238000013508 migration Methods 0.000 claims abstract description 33
- 238000002592 echocardiography Methods 0.000 claims abstract description 19
- 239000011159 matrix material Substances 0.000 claims description 50
- 239000013598 vector Substances 0.000 claims description 40
- 238000000034 method Methods 0.000 claims description 35
- 230000006870 function Effects 0.000 claims description 28
- 238000005070 sampling Methods 0.000 claims description 21
- 238000013215 result calculation Methods 0.000 claims description 11
- 230000008602 contraction Effects 0.000 claims description 7
- 230000009977 dual effect Effects 0.000 claims description 6
- 238000004590 computer program Methods 0.000 claims description 5
- 230000033001 locomotion Effects 0.000 abstract description 15
- 238000010586 diagram Methods 0.000 description 16
- 230000008569 process Effects 0.000 description 12
- 230000000875 corresponding effect Effects 0.000 description 11
- 238000005259 measurement Methods 0.000 description 8
- 238000004422 calculation algorithm Methods 0.000 description 6
- 230000008859 change Effects 0.000 description 5
- 230000001131 transforming effect Effects 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 230000001133 acceleration Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000002596 correlated effect Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- 230000003044 adaptive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000008447 perception Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
Landscapes
- Radar Systems Or Details Thereof (AREA)
Abstract
The application provides a forward-looking imaging method and device for a vehicle and a double-antenna radar, and relates to the field of radar imaging. The front-view imaging method comprises the steps of respectively mixing echo signals of a first antenna and a second antenna with transmitting signals to obtain mixed echo signals; wherein the echo signal is the echo signal of the observation target of the radar; performing range pulse compression on the mixed echo signals, and performing range migration correction on the compressed echo signals to obtain single-channel synthetic aperture echoes of the first antenna and the second antenna respectively; constructing a linear equation for the first antenna and the second antenna based on the single channel synthetic aperture echo; the linear equation is solved to obtain the imaging result. The forward-looking imaging method of the double-antenna radar provided by the embodiment of the application fully utilizes aperture information formed by the motion of the motion platform, and obtains a high-resolution imaging result with left-right multiple-power Lei Duichen blurring in a forward-looking area.
Description
Technical Field
The application relates to the field of radar imaging, in particular to a forward-looking imaging method and device of a vehicle and a double-antenna radar.
Background
Optical cameras or lidars are often used in the field of autopilot to provide detailed perception of the surroundings of a vehicle in order to make accurate path planning, which adapts to changes in road layout. But optical cameras or lidars perform poorly in challenging weather conditions, such as heavy rain weather, heavy fog weather, etc.; therefore, radar imaging technology capable of overcoming this problem is attracting attention.
Currently, multi-antenna radars are constructed by arranging multiple transmit antennas and multiple receive antennas on a single platform, which, while having the potential for forward-looking imaging, often have very low azimuth resolution due to the limited size of the platform.
Disclosure of Invention
The embodiment of the application aims to provide a forward-looking imaging method and device of a vehicle and a double-antenna radar, which are used for obtaining high-resolution imaging results with left-right multi-purpose Lei Duichen blur in a forward-looking area through aperture information formed by movement of a moving platform. And a linear model is established by utilizing the wave path difference of the two antennas, so that a high-resolution imaging result without blurring is solved.
In a first aspect, an embodiment of the present application provides a forward-looking imaging method of a dual-antenna radar, where the method includes: mixing echo signals of the first antenna and the second antenna with the transmitting signals respectively to obtain mixed echo signals; wherein the echo signal is the echo signal of the observation target of the radar; performing range pulse compression on the mixed echo signals, and performing range migration correction on the compressed echo signals to obtain single-channel synthetic aperture echoes of the first antenna and the second antenna respectively; constructing a linear equation for the first antenna and the second antenna based on the single channel synthetic aperture echo; according to the linear equation, an imaging result is obtained.
In the implementation process, the forward-looking imaging method of the dual-antenna radar provided by the embodiment of the application mixes the transmitting signals of the first antenna and the second antenna with the echo signals to obtain the mixed echo signals, and the frequency of the mixed echo signals is changed from high frequency to intermediate frequency. And the mixed echo signals are subjected to distance pulse compression, so that the accuracy of distance measurement is improved. Further, performing range migration correction on the compressed echo signals to eliminate range ambiguity caused by motion; and then synthesizing an antenna with a large aperture effect on the minimum observation unit to obtain a single-channel synthetic aperture echo. Constructing a linear equation for the first and second antennas based on the synthetic aperture echoes; and solving the constructed linear equation to obtain an imaging result. The measuring accuracy of the radar system to the target distance is improved. The forward-looking imaging method of the double-antenna radar provided by the embodiment of the application eliminates the range ambiguity caused by motion, and is beneficial to obtaining a more accurate target position in imaging; by constructing and solving the linear equation, the Doppler left/right stacking ambiguity problem possibly occurring in the single-channel synthetic aperture result is solved, and the imaging quality is improved.
Optionally, in an embodiment of the present application, performing distance pulse compression on the mixed echo signal includes: fourier transforming is performed on the mixed echo signals to achieve distance pulse compression on the mixed echo signals.
In the implementation process, the embodiment of the application realizes the pulse compression of the mixed signal distance by carrying out Fourier transform on the mixed echo signal, and improves the measurement precision and resolution of the dual-antenna radar of the embodiment of the application on the target distance.
Optionally, in this embodiment of the present application, performing range migration correction on the compressed echo signal to obtain single-channel synthetic aperture echoes of the first antenna and the second antenna respectively, where the method includes: respectively acquiring Taylor expansion constant items of the two-way echo distances corresponding to echo signals of the first antenna and the second antenna; and carrying a constant term of Taylor expansion of the double-pass echo distance into the compressed echo signal to obtain a single-channel synthetic aperture echo of the first antenna and a single-channel synthetic aperture echo of the second antenna.
In the implementation process, in order to perform range migration correction on the echo signals after the range compression, the forward-looking imaging method of the dual-antenna radar provided by the embodiment of the application performs taylor expansion on the double-pass echo distance, and performs accurate correction on the first-order distance offset and the second-order distance offset; the method realizes the accurate correction of the range migration in the radar echo signal, thereby improving the imaging quality and the range measurement precision of the radar system.
Optionally, in an embodiment of the present application, constructing a linear equation for the first antenna and the second antenna based on the single-channel synthetic aperture echo includes: according to the single-channel synthetic aperture echo, M receiving signals in the sampling of M directions of the first antenna and the second antenna on the sampling unit are calculated respectively to form a first antenna echo matrix and a second antenna echo matrix respectively; and combining the first antenna echo matrix and the second antenna echo matrix to obtain a linear equation.
Optionally, in an embodiment of the present application, the first antenna echo matrix includes: s is S a ＝A a ·σ+B a The second antenna echo matrix includes: s is S b ＝A b ·σ+B b The method comprises the steps of carrying out a first treatment on the surface of the Sigma represents the scattering coefficient vector of the observation target, S a Is the echo vector of the first antenna S b Is the echo vector of the second antenna, A a A is a guide matrix of the first antenna b Is the guiding matrix of the second antenna, B a Is the noise vector of the first antenna, B b A noise vector for the second antenna; combining the first antenna echo matrix and the second antenna echo matrix to obtain a linear equation, including: matrix S of first antenna echo a ＝A a ·σ+B a And a second antenna echo matrix S b ＝A b ·σ+B b Simultaneously, a linear equation is obtained: s=a·σ+b; wherein,
in the implementation process, because the echoes in the first antenna and the second antenna have differences in the arrangement positions of the antennas, corresponding guide matrixes A_a and A_b also have differences, and the two guide matrixes are combined to solve simultaneously, so that an imaging result without ambiguity of a single sampling unit can be obtained.
Optionally, in an embodiment of the present application, obtaining the imaging result according to a linear equation includes: constructing a scattering coefficient vector function on an observation target based on a linear equation; controlling the scattering coefficient vector function to iterate to convergence by using the contraction function; under the condition that the obtained scattering coefficient vector function converges, the corresponding scattering coefficient value.
Optionally, in an embodiment of the present application, the scattering coefficient vector function includes a regularization term.
In the implementation process, the forward-looking imaging method of the dual-antenna radar provided by the embodiment of the application provides synthetic aperture information by fully utilizing platform motion, and then establishes a linear equation by combining echo differences in the dual antennas, and reconstructs a target scattering coefficient by using an iterative self-adaptive soft threshold algorithm, so that a forward-looking high-resolution imaging result is obtained.
In a second aspect, an embodiment of the present application provides a forward-looking imaging device of a dual-antenna radar, where the device includes a mixing module, a pulse compression module, a migration correction module, and an imaging result calculation module; the frequency mixing module is used for respectively mixing echo signals of the first antenna and the second antenna with the transmitting signals to obtain mixed echo signals; wherein the echo signal is the echo signal of the observation target of the radar; the pulse compression module is used for performing distance pulse compression on the mixed echo signals. The migration correction module is used for performing range migration correction on the compressed echo signals to obtain single-channel synthetic aperture echoes of the first antenna and the second antenna respectively; the imaging result calculation module is used for constructing a linear equation about the first antenna and the second antenna based on the single-channel synthetic aperture echo; according to the linear equation, an imaging result is obtained.
In a third aspect, an embodiment of the present application provides a vehicle, where the vehicle includes a memory and a processor, where the memory stores program instructions that, when executed by the processor, perform the steps in any implementation manner of the first aspect.
In a fourth aspect, embodiments of the present application further provide a computer readable storage medium having stored therein computer program instructions which, when read and executed by a processor, perform the steps in any implementation manner of the first aspect.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a flowchart of a front view imaging method of a dual-antenna radar according to an embodiment of the present application;
FIG. 2 is a geometric diagram of dual antenna radar front view imaging provided in an embodiment of the present application;
FIG. 3 is an intent of an observation target in an observation scenario provided in an embodiment of the present application;
fig. 4 is a schematic diagram of pulse compression echo of a single antenna in an observation scene according to an embodiment of the present application;
fig. 5 is a range migration correction flowchart provided in an embodiment of the present application;
fig. 6 is a diagram of echo range migration correction results of a single antenna in an observation scene provided in an embodiment of the present application;
FIG. 7 is a flow chart of the construction of a thread equation provided in an embodiment of the present application;
FIG. 8 is a flow chart of imaging result calculation provided in real time in the present application;
FIG. 9 is a schematic diagram of front-view imaging of the observation target of FIG. 3 provided in an embodiment of the present application;
FIG. 10 is an imaging cross-sectional view of the observation target of FIG. 3 provided in an embodiment of the present application;
fig. 11 is a schematic block diagram of a front view imaging device of a dual-antenna radar according to an embodiment of the present application;
fig. 12 is a schematic structural diagram of a vehicle according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. For example, the flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. In addition, functional modules in the embodiments of the present invention may be integrated together to form a single part, or each module may exist alone, or two or more modules may be integrated to form a single part.
Radar imaging technology is a technology that uses a radar system to acquire spatial distribution information of a target or ground object and presents the spatial distribution information in an image form. Radar imaging can be performed in different environments and weather conditions because the radar system is not affected by weather constraints, such as rain, fog or clouds, to which the optical sensor is subjected. Therefore, radar imaging is widely used in the fields of military, aviation, weather, geological exploration, environmental monitoring and the like.
In some comparative embodiments, the MUSIC algorithm is applied to multi-antenna radar imaging, but the algorithm needs to know the number of sources and needs multiple snapshot data to obtain a better imaging result. In some comparative embodiments, a compressive sensing based algorithm is applied to MIMO forward-looking imaging, but the performance of imaging may be limited by the signal-to-noise ratio of the echo data. In some comparative embodiments, forward looking imaging is performed using a synthetic aperture radar scheme of multi-antenna radar, but the scheme has little change in viewing angle in the forward viewing region and poor azimuthal resolution.
The inventor researches and discovers that in the process, not only the left-right Doppler symmetrical blurring exists in the single antenna forward-looking imaging, but also the problem of low imaging resolution of a front-looking area caused by small array size is needed to be overcome, and the high-resolution forward-looking imaging is needed to be overcome.
Based on the above, the application provides a forward-looking imaging method and device of a vehicle and a double-antenna radar, wherein the forward-looking imaging method of the double-antenna radar is characterized in that two antennas are arranged on a mobile platform to acquire echo data of an observation target acquired by the two antennas in an observation scene, the echo data are processed, and aperture information formed by platform movement is utilized; and combining echo data of the two antennas, designing a guide matrix, establishing a linear model, and finally reconstructing a target scattering coefficient by using an iterative soft threshold contraction algorithm to obtain a forward-looking high-resolution imaging result.
Referring to fig. 1, fig. 1 is a flowchart of a front view imaging method of a dual-antenna radar according to an embodiment of the present application; the present application provides a forward looking imaging method of a dual antenna radar, which may be performed by the electronic device of fig. 12. The forward-looking imaging method of the double-antenna radar comprises the following steps:
step S100: and respectively mixing echo signals of the first antenna and the second antenna with the transmitting signals to obtain mixed echo signals.
The echo signal is the echo signal of the radar observation target.
In the step S100, two antennas are disposed on a mobile platform in the observation space, where the mobile platform may be a vehicle, for example, please refer to fig. 2, fig. 2 is a geometric configuration diagram of a dual-antenna radar front view imaging provided in the embodiment of the present application, and may be arranged in a manner shown in fig. 2, assuming that the first antenna and the second antenna are respectively located on two sides of a coordinate origin on the y-axis, and an array element interval of the first antenna and the second antenna is d. And respectively mixing the transmitting signals of the first antenna and the second antenna with the acquired echo signals to obtain the echo signals after mixing. The echo signal is returned to the radar after a certain observation target in the observation space receives the transmission signal.
It can be understood that the transmitting signal and the echo signal are mixed to obtain a signal with a new frequency, and in the embodiment of the present application, the signal with the new frequency still has the characteristic of the initial echo signal, but the echo signal after mixing is reduced from the high-frequency signal to the intermediate-frequency signal, so that the sampling can be conveniently performed.
It should be noted that, the radar system in the embodiment of the present application is a Frequency Modulated Continuous Wave (FMCW) radar system, that is, a radar system that uses a frequency modulated signal to perform target ranging and speed measurement; FMCW radar transmits a continuous frequency modulated signal whose frequency varies linearly with time.
For example, please refer to fig. 3, fig. 3 is an intention of an observation target in an observation scene provided in an embodiment of the present application; the direction length of the observed scene is typically-10 degrees to 10 degrees, the distance length is typically 150 to 250m, for a single antenna, the single antenna has azimuth sampling points and distance sampling points, as shown in fig. 3, the scene can be uniformly divided into 64 multiplied by 256 grids, each grid can be regarded as a minimum sampling unit, and the central position of the observed scene is X c ＝200m，Y c =0m; assume that the position of the observation target in the observation scene is(there are 5 observation targets in fig. 3, positions (200,0.8), (200,1.5), (200,3.5), (200,4.0), and (200,4.5)), the two-way echo distance of the observation targets to the two antennas can be expressed as:wherein R is Rx (t,y i ) R is the transmission distance of the antenna Tx (t) is the receiving distance of the antenna, t is the slow time, < ->To show the time of the fast, y u Is the azimuth position of the antenna.
Further, after mixing the echo signal and the transmitting signal, the mixed echo signal is obtainedCan be expressed as:
wherein sigma 0 K is a constant positively correlated with the observed target energy magnitude r For distance frequency modulation, c is the speed of light.
Step S200: and performing range pulse compression on the mixed echo signals, and performing range migration correction on the compressed echo signals to obtain single-channel synthetic aperture echoes of the first antenna and the second antenna respectively.
In the step S200, the mixed echo signals are subjected to distance pulse compression, and the mixed echo signals are subjected to pulse compression, so that more accurate measurement of the distance is realized. And further, performing range migration correction on the echo signals after pulse compression, and obtaining single-channel synthetic aperture echoes of the two antennas after correction.
The single-channel synthetic aperture echo mentioned above means that in the observation environment, an effect equivalent to an antenna having a large aperture is synthesized by recording echo signals at different positions on a minimum observation unit (or referred to as a distance unit).
In synthetic aperture radars, the motion of the radar platform or the motion of the target causes frequency modulation of the echo signal, resulting in ambiguity in range direction; the goal of range-shift correction is to eliminate or reduce this blurring, making the imaging result more accurate.
Step S300: based on the single channel synthetic aperture echo, linear equations are constructed for the first antenna and the second antenna.
In the above step S300, the linear equations for the first antenna and the second antenna are constructed based on the single-channel synthetic aperture echo. For either the first antenna or the second antenna, the single synthetic aperture results, since there is only one channel, the targets on the left side of the antenna and on the right side of the antenna have the same Doppler change characteristics, and there is Doppler left/right pile-up ambiguity for the imaging result that is found by means of the single synthetic aperture results (radar systems have a limited range of Doppler shifts beyond which the shift is blurred to opposite directions, i.e. the left and right sides may pile up together).
Step S400: according to the linear equation, an imaging result is obtained.
In the above step S400, the imaging result is obtained according to a linear equation constructed based on the single-channel synthetic aperture echo of the first antenna and the single-channel synthetic aperture echo of the second antenna.
As can be seen from fig. 1, in the forward-looking imaging method of the dual-antenna radar provided in the embodiment of the present application, the transmitting signals of the first antenna and the second antenna are mixed with the echo signals, so as to obtain the mixed echo signals, and the frequency of the mixed echo signals is changed from high frequency to intermediate frequency. And the mixed echo signals are subjected to distance pulse compression, so that the accuracy of distance measurement is improved. Further, performing range migration correction on the compressed echo signals to eliminate range ambiguity caused by motion; and then synthesizing an antenna with a large aperture effect on the minimum observation unit to obtain a single-channel synthetic aperture echo. Constructing a linear equation for the first and second antennas based on the synthetic aperture echoes; and solving the constructed linear equation to obtain an imaging result. The measuring accuracy of the radar system to the target distance is improved. The forward-looking imaging method of the double-antenna radar provided by the embodiment of the application eliminates the range ambiguity caused by motion, and is beneficial to obtaining a more accurate target position in imaging; by constructing and solving the linear equation, the Doppler left/right stacking ambiguity problem possibly occurring in the single-channel synthetic aperture result is solved, and the imaging quality is improved.
In an alternative embodiment, the distance pulse compression of the mixed echo signal may be achieved by:
fourier transforming is performed on the mixed echo signals to achieve distance pulse compression on the mixed echo signals.
Illustratively, the above is received, mixed echo signalsSince in FMCW radar the transmitted signal is a frequency modulated signal, its frequency varies linearly with time; the received echo signal is mixed to obtain a difference frequency signal (the above-mentioned mixingThe echo signal after). Since the phase change is correlated with the change in the observation target distance, information about the distance can be obtained by deriving the phase of the mixed difference frequency signal.
In the frequency domain of the fourier transform, pulse compression can be achieved by fourier transforming the signal due to the chirping characteristic of the difference frequency signal, and a wide pulse signal is compressed into a narrow pulse, thereby improving the distance resolution.
For a pair ofPerforming Fourier transform to obtain a distance pulse compression result:
wherein the FFT is a fourier transform operator.
The echo after distance pulse compression in the embodiment of the application is shown in fig. 4, and fig. 4 is a schematic diagram of pulse compression echo of a single antenna in an observation scene provided in the embodiment of the application; in fig. 4, the abscissa range (m) is the sampling distance, azimuth Samples are Azimuth Samples, and the echo after the distance pulse compression can be seen from fig. 4, so that the distance resolution is better.
Therefore, according to the embodiment of the application, the mixed signal distance is compressed to the pulse by carrying out Fourier transform on the mixed echo signal, so that the measurement accuracy and resolution of the dual-antenna radar to the target distance are improved.
Referring to fig. 5, fig. 5 is a range migration correction flowchart provided in an embodiment of the present application; in an alternative embodiment, the foregoing performing range migration correction on the compressed echo signal in step S200 to obtain single-channel synthetic aperture echoes of the first antenna and the second antenna respectively may be implemented by the following steps:
step S210: and respectively acquiring Taylor expansion constant items of the double-pass echo distances corresponding to the echo signals of the first antenna and the second antenna.
In the step S210, taylor expansion is performed on the two-way echo distance corresponding to the echo signal of the first antenna and the two-way echo distance corresponding to the echo signal of the second antenna, and a constant term of the corresponding taylor expansion is obtained.
Illustratively, the two-pass echo distanceThe taylor expansion at t=0 can be expressed as:
since the velocity of motion can be accurately fed back by the inertial navigation device, range migration is determined, and therefore, the first-order and second-order range offset can be accurately corrected. The primary term of the Taylor expansion is the first-order distance offset of the echo signal, and is generally related to the motion speed of an observation target; the quadratic term of the taylor expansion is the second order distance offset of the echo signal and is usually related to the acceleration of the observed object. The constant term of taylor expansion represents the value of the distance at time t=0, and the first and second time derivative terms represent the influence of speed and acceleration, so that only the constant term remains in the course of range migration correction.
Step S220: and carrying a constant term of Taylor expansion of the double-pass echo distance into the compressed echo signal to obtain a single-channel synthetic aperture echo of the first antenna and a single-channel synthetic aperture echo of the second antenna.
In the step S220, the taylor expansion constant term of the two-way echo distance is carried into the compressed echo signal, so as to obtain the single-channel synthetic aperture echoes of the two antennas respectively. Illustratively, the above equation 3) is carried into the echo signal equation 2) after the range-wise pulse compression, and the echo signal after the range migration correction is obtained as follows:
at this time, the single channel synthetic aperture echo of the first antenna at a certain minimum sampling unit:
single channel synthetic aperture echo of the second antenna:
in the formulas 5) and 6), d represents an antenna element interval.
Referring to fig. 6 on the basis of fig. 5, fig. 6 is a diagram of an echo range migration correction result of a single antenna in an observation scene provided in an embodiment of the present application; the range change of the echo signal due to the radar platform motion is corrected in fig. 6 with respect to fig. 4, where no range migration correction is performed.
As can be seen from fig. 5, in the forward-looking imaging method of the dual-antenna radar provided by the embodiment of the present application, in order to perform range migration correction on the echo signal after range compression, taylor expansion is performed on the dual-range echo range, and precise correction is performed on the first-order range offset and the second-order range offset; the method realizes the accurate correction of the range migration in the radar echo signal, thereby improving the imaging quality and the range measurement precision of the radar system.
Referring to fig. 7, fig. 7 is a flowchart of thread equation construction provided in an embodiment of the present application; in an alternative embodiment, the above step S300 is implemented by constructing a linear equation for the first antenna and the second antenna based on the single-channel synthetic aperture echo, by:
step S310: according to the single-channel synthetic aperture echo, M receiving signals of the first antenna and the second antenna in M azimuth sampling on the sampling unit are calculated respectively to form a first antenna echo matrix and a second antenna echo matrix respectively.
In the above step S310, M received signals in the sampling of M orientations of the first antenna and the second antenna on the sampling unit are calculated from the single-channel synthetic aperture echoes (equation 5) and equation 6), respectively. If the azimuth consists of M samples and N remote narrowband signals incident on the synthetic aperture trajectory, then taking the first antenna as an example, the received signal sampled for the ith azimuth of the first antenna on some minimum sampling unit can be expressed as:
in formula 7), σ k Representing the scattering coefficient of the kth object, b ai Noise, τ, representing the ith bit sample ki Representing the delay of the stage when the kth signal arrives at the ith bit sample, i.e. the path difference delay,representing the wave path difference phase, f 0 Representing the carrier frequency of the transmitted signal.
The echo of a distance cell formed for different azimuth sampling instants can be written as:
i.e. the echo matrix described above, the echo matrix of a similar second antenna can also be represented in the form described above. Formula 8) above may be represented as S a ＝A a ·σ+B a Wherein, the method comprises the steps of, wherein, correspondingly, the echo matrix of the second antenna may be denoted as S b ＝A b ·σ+B b 。
Representing the position P (x) of the kth object by dividing the observation environment into the same grid k ,y k ) The position of the sampling platform at a time can be expressed asThus, the following formula is used to obtain
Step S320: and combining the first antenna echo matrix and the second antenna echo matrix to obtain a linear equation.
In the above step S320, the first antenna echo matrix and the second antenna echo matrix are combined to obtain a linear equation:the linear equation is further expressed as:
s=a·σ+b formula 9),
in the above formula, sigma represents a scattering coefficient vector of an observation target, S a Is the echo vector of the first antenna S b Is the echo vector of the second antenna, A a A is a guide matrix of the first antenna b Is the guiding matrix of the second antenna, B a Is the noise vector of the first antenna, B b Is the noise vector of the second antenna.
As can be seen from fig. 7, since there is a difference in the arrangement positions of the antennas due to echoes in the first antenna and the second antenna, the corresponding steering matrix a a And A b And the two guide matrixes are combined to solve simultaneously, so that an imaging result without blurring of a single sampling unit can be obtained.
Referring to fig. 8, fig. 8 is a flowchart of imaging result calculation provided in real time in the present application; in an alternative embodiment, the step S400 may be implemented according to a linear equation, where the imaging result is obtained by:
step S410: based on the linear equation, a scattering coefficient vector function with respect to the observation target is constructed.
In the above step S410, based on the linear equation 9), a scattering coefficient vector function with respect to the observation target is constructed; scattering coefficients are used in the radar field to describe the interaction between radar waves and targets, and scattering coefficient vectors can reflect the response of targets to radar waves of different directions and polarization states.
Solving the scattering coefficient vector σ of equation 9) can be regarded as solving the inverse problem of least squares, and can be expressed as:
min||S-A·σ|| 2 +μ||σ‖ 1 11, a combination of two or more of the following
Wherein μ σ 2 Is a regularization term, μ represents a regularization coefficient, the regularization term is added to avoid overfitting due to the steering matrixMay be ill-conditioned, adversely affecting super-resolution at low signal-to-noise ratios, and regularization terms as described above may be introduced. Illustratively, the regularization coefficient μmay be set to 0.1.
Further, the method comprises the steps of, let f (σ) =set S-A. Sigmse:Sup>A. I 2 Then solve equation 11), the iterative equation for gradient descent can be expressed as:
wherein t is k Representing step size, when t k ∈(0,1/||A H A||) can ensure sigma k And (5) convergence.
Further, in conjunction with regularization term and equation 11), equation 12) can be expressed in turn as:
and merging the similar items, and obtaining the following form of the scattering coefficient vector function after ignoring the constant items:
step S420: and controlling the scattering coefficient vector function to iterate until convergence according to the contraction function.
In the above step S420, σ is calculated k When the optimization problem in one dimension is solved, the formula (14) is simplified as follows:
σ k ＝τ[σ k-1 -2t k A H M×n (A H M×N σ k-1 -S M×1 )]equation 15) in equation 15), τ is a contraction function, and the iteration threshold constant a is selected, where the contraction function may be:sgn (·) is a sign function.
Step S430: under the condition that the obtained scattering coefficient vector function converges, the corresponding scattering coefficient value.
In step S430 described above, since σ is related to the observation target, the observation target is moving, and therefore, an iterative solution is required. And (3) iterating according to the formula 15) until the scattering coefficient vector function converges, and obtaining a super-resolution imaging result of object blurring.
Referring to fig. 9 and fig. 10, fig. 9 is a schematic diagram of forward-looking imaging of an observation target in fig. 3 according to an embodiment of the present application, which is an imaging result obtained by the forward-looking imaging method of the dual-antenna radar according to the embodiment of the present application; FIG. 10 is an imaging cross-sectional view of the observation target of FIG. 3 provided in an embodiment of the present application; in fig. 9 and 10, the horizontal axis represents Azimuth (Azimuth), and the vertical axis of fig. 10 represents normalized amplitude (Normalized amplitude) of the cross section; as can be seen from fig. 9 and fig. 10, the imaging result obtained by the forward-looking imaging method of the dual-antenna radar provided by the embodiment of the application has no blurring of left and right, and the forward-looking imaging resolution is higher.
As can be seen from fig. 8, the forward-looking imaging method of the dual-antenna radar provided by the embodiment of the application provides synthetic aperture information by fully utilizing platform motion, and combines echo differences in dual antennas to establish a linear equation, and uses an iterative adaptive soft threshold algorithm to reconstruct a target scattering coefficient, thereby obtaining a forward-looking high-resolution imaging result.
In an alternative embodiment, when the forward-looking imaging method of the dual-antenna radar is used in imaging of the vehicle-mounted radar, the vehicle-mounted radar may be configured in table 1; based on the correlation configuration in table 1, high-resolution imaging of the front view of the vehicle can be achieved depending on the implementation in the front view imaging method of the double antenna radar described above.
TABLE 1
Referring to fig. 11, fig. 11 is a schematic block diagram of a front view imaging device of a dual-antenna radar according to an embodiment of the present application; the present application also provides a front-view imaging device of a dual-antenna radar, the front-view imaging device 100 of the dual-antenna radar including: a mixing module 110, a pulse compression module 120, a migration correction module 130, and an imaging result calculation module 140.
The mixing module 110 is configured to mix echo signals of the first antenna and the second antenna with the transmitting signal, respectively, to obtain mixed echo signals; the echo signal is the echo signal of the radar observation target.
The pulse compression module 120 is configured to perform distance pulse compression on the mixed echo signal.
The migration correction module 130 is configured to perform range migration correction on the compressed echo signal, so as to obtain single-channel synthetic aperture echoes of the first antenna and the second antenna respectively;
the imaging result calculation module 140 is configured to construct a linear equation for the first antenna and the second antenna based on the single-channel synthetic aperture echo; according to the linear equation, an imaging result is obtained.
In an alternative embodiment, in the process of performing distance pulse compression on the mixed echo signal, the pulse compression module 120 is specifically configured to: fourier transforming is performed on the mixed echo signals to achieve distance pulse compression on the mixed echo signals.
In an alternative embodiment, in the process of performing range migration correction on the compressed echo signal to obtain single-channel synthetic aperture echoes of the first antenna and the second antenna, the migration correction module 130 is specifically configured to: respectively acquiring Taylor expansion constant items of the two-way echo distances corresponding to echo signals of the first antenna and the second antenna; and carrying a constant term of Taylor expansion of the double-pass echo distance into the compressed echo signal to obtain a single-channel synthetic aperture echo of the first antenna and a single-channel synthetic aperture echo of the second antenna.
In an alternative embodiment, in constructing the linear equation for the first antenna and the second antenna based on the single-channel synthetic aperture echo, the imaging result calculation module 140 is specifically configured to: according to the single-channel synthetic aperture echo, M receiving signals in the sampling of M directions of the first antenna and the second antenna on the sampling unit are calculated respectively to form a first antenna echo matrix and a second antenna echo matrix respectively; and combining the first antenna echo matrix and the second antenna echo matrix to obtain a linear equation.
In an alternative embodiment, wherein the first antenna echo matrix comprises: s is S a ＝A a ·σ+B a The second antenna echo matrix includes: s is S b ＝A b ·σ+B b The method comprises the steps of carrying out a first treatment on the surface of the Sigma represents the scattering coefficient vector of the observation target, S a Is the echo vector of the first antenna S b Is the echo vector of the second antenna, A a A is a guide matrix of the first antenna b Is the guiding matrix of the second antenna, B a Is the noise vector of the first antenna, B b A noise vector for the second antenna; in the process of combining the first antenna echo matrix and the second antenna echo matrix to obtain the linear equation, the imaging result calculation module 140 is specifically configured to: matrix S of first antenna echo a ＝A a ·σ+B a And a second antenna echo matrix S b ＝A b ·σ+B b Simultaneously, a linear equation is obtained: s=a·σ+b; wherein,
in an alternative embodiment, in obtaining the imaging result according to the linear equation, the imaging result calculation module 140 is specifically configured to: constructing a scattering coefficient vector function on an observation target based on a linear equation; controlling the scattering coefficient vector function to iterate to convergence by using the contraction function; under the condition that the obtained scattering coefficient vector function converges, the corresponding scattering coefficient value.
In an alternative embodiment, wherein the scattering coefficient vector function comprises a regularization term.
Referring to fig. 12, fig. 12 is a schematic structural diagram of a vehicle according to an embodiment of the present application. The vehicle 300 provided in the embodiment of the present application includes: a processor 301 and a memory 302, the memory 302 storing machine readable instructions executable by the processor 301, the machine readable instructions being executable by the processor 301 to perform steps in any one of the implementations of the forward looking imaging method of a dual antenna radar as described above.
Based on the same inventive concept, the embodiments of the present application further provide a computer readable storage medium, where a computer program instruction is stored, where the computer program instruction, when read and executed by a processor, performs the steps in any implementation manner of the forward-looking imaging method of the dual-antenna radar.
The computer readable storage medium may be any of various media capable of storing program codes, such as random access Memory (Random Access Memory, RAM), read Only Memory (ROM), programmable Read Only Memory (Programmable Read-Only Memory, PROM), erasable programmable Read Only Memory (Erasable Programmable Read-Only Memory, EPROM), electrically erasable programmable Read Only Memory (Electric Erasable Programmable Read-Only Memory, EEPROM), and the like.
In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element.
The foregoing is merely exemplary embodiments of the present application and is not intended to limit the scope of the present application, and various modifications and variations may be suggested to one skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.
Claims (10)
1. A method of forward-looking imaging for a dual antenna radar, the method comprising:
mixing echo signals of the first antenna and the second antenna with the transmitting signals respectively to obtain mixed echo signals; wherein the echo signal is the echo signal of the observation target of the radar;
performing range pulse compression on the mixed echo signals, and performing range migration correction on the compressed echo signals to obtain single-channel synthetic aperture echoes of the first antenna and the second antenna respectively;
constructing a linear equation for the first and second antennas based on the single channel synthetic aperture echoes;
and obtaining an imaging result according to the linear equation.
2. The method of claim 1, wherein said distance-wise pulse compressing the mixed echo signal comprises:
and carrying out Fourier transform on the mixed echo signals to realize distance pulse compression on the mixed echo signals.
3. The method according to claim 1, wherein the performing range migration correction on the compressed echo signals to obtain single-channel synthetic aperture echoes of the first antenna and the second antenna respectively comprises:
respectively acquiring Taylor expansion constant items of double-pass echo distances corresponding to echo signals of the first antenna and the second antenna;
and bringing the constant term of Taylor expansion of the double-pass echo distance into the compressed echo signal to obtain the single-channel synthetic aperture echo of the first antenna and the single-channel synthetic aperture echo of the second antenna.
4. The method of claim 1, wherein constructing a linear equation for the first and second antennas based on the single channel synthetic aperture echo comprises:
according to the single-channel synthetic aperture echo, M receiving signals in the sampling of M directions of the first antenna and the second antenna on the sampling unit are calculated respectively to form a first antenna echo matrix and a second antenna echo matrix respectively;
and combining the first antenna echo matrix and the second antenna echo matrix to obtain the linear equation.
5. The method of claim 4, wherein the first antenna echo matrix comprises: s is S a ＝A a ·σ+B a The second antenna echo matrix includes: s is S b ＝A b ·σ+B b The method comprises the steps of carrying out a first treatment on the surface of the Sigma represents a scattering coefficient vector of the observation target, S a For the echo vector of the first antenna, S b For the echo vector of the second antenna, A a A is a guide matrix of the first antenna b For the steering matrix of the second antenna, B a B is the noise vector of the first antenna b A noise vector for the second antenna;
the step of combining the first antenna echo matrix and the second antenna echo matrix to obtain the linear equation comprises the following steps:
said first antenna echo matrix S a ＝A a ·σ+B a And the second antenna echo matrix S b ＝A b ·σ+B b Simultaneously, the linear equation is obtained as follows: s=a·σ+b; wherein,
6. the method of claim 1, wherein said obtaining imaging results from said linear equation comprises:
constructing a scattering coefficient vector function with respect to the observation target based on the linear equation;
controlling the scattering coefficient vector function to iterate to convergence by using a contraction function;
and under the condition that the scattering coefficient vector function converges, the corresponding scattering coefficient value is obtained.
7. The method of claim 6, wherein the scattering coefficient vector function comprises a regularization term.
8. The device is characterized by comprising a mixing module, a pulse compression module, a migration correction module and an imaging result calculation module;
the frequency mixing module is used for respectively mixing echo signals of the first antenna and the second antenna with the transmitting signals to obtain mixed echo signals; wherein the echo signal is the echo signal of the observation target of the radar;
the pulse compression module is used for performing distance pulse compression on the mixed echo signals.
The migration correction module is used for performing range migration correction on the compressed echo signals to obtain single-channel synthetic aperture echoes of the first antenna and the second antenna respectively;
the imaging result calculation module is used for constructing a linear equation about the first antenna and the second antenna based on the single-channel synthetic aperture echo; and obtaining an imaging result according to the linear equation.
9. A vehicle comprising a memory and a processor, the memory having stored therein program instructions which, when executed by the processor, perform the steps of the method of any of claims 1-7.
10. A computer readable storage medium, characterized in that the computer readable storage medium has stored therein computer program instructions which, when executed by a processor, perform the steps of the method of any of claims 1-7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311753640.5A CN117724100A (en) | 2023-12-18 | 2023-12-18 | Forward-looking imaging method and device for vehicle and double-antenna radar |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311753640.5A CN117724100A (en) | 2023-12-18 | 2023-12-18 | Forward-looking imaging method and device for vehicle and double-antenna radar |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117724100A true CN117724100A (en) | 2024-03-19 |
Family
ID=90204917
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311753640.5A Pending CN117724100A (en) | 2023-12-18 | 2023-12-18 | Forward-looking imaging method and device for vehicle and double-antenna radar |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117724100A (en) |
-
2023
- 2023-12-18 CN CN202311753640.5A patent/CN117724100A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11243304B2 (en) | Systems and methods for interpolated virtual aperature radar tracking | |
| Raney | Synthetic aperture imaging radar and moving targets | |
| CN108051809B (en) | Moving target imaging method and device based on Radon transformation and electronic equipment | |
| Tagliaferri et al. | Navigation-aided automotive SAR for high-resolution imaging of driving environments | |
| KR102090318B1 (en) | Image decoding apparatus based on airborn and method of decoding image using the same | |
| Sjogren et al. | Moving target relative speed estimation and refocusing in synthetic aperture radar images | |
| CN113687356B (en) | Airborne multichannel circular SAR moving target detection and estimation method | |
| KR930000138B1 (en) | Sar signal azimuth ambiguity cancellation | |
| Yoon et al. | MVDR beamforming for through-the-wall radar imaging | |
| CN110632594A (en) | Long-wavelength spaceborne SAR imaging method | |
| US6628844B1 (en) | High definition imaging apparatus and method | |
| KR102128156B1 (en) | Polar format processing based moving target detection apparatus and method in bistatic ground-to-air radar environment | |
| CN113670301A (en) | Airborne SAR motion compensation method based on inertial navigation system parameters | |
| CN111665501B (en) | MIMO radar two-dimensional imaging method based on improved CBP | |
| Chung et al. | Analysis on the impact of constellation configuration over multistatic SAR images | |
| Yang | Study on ground moving target indication and imaging technique of airborne SAR | |
| Bezvesilniy et al. | Synthetic aperture radar systems for small aircrafts: Data processing approaches | |
| CN116774178A (en) | Short-range frequency domain three-dimensional imaging method of single-frequency MIMO arc array radar | |
| Weishaupt et al. | Calibration and signal processing of polarimetric radar data in automotive applications | |
| Chen et al. | Forward looking imaging of airborne multichannel radar based on modified iaa | |
| CN116400353A (en) | Real synthetic aperture imaging method for multichannel radar forward imaging | |
| CN117724100A (en) | Forward-looking imaging method and device for vehicle and double-antenna radar | |
| US20230152436A1 (en) | System and Method for Determining Angle of Arrival in a Radar Based Point Cloud Generation | |
| Rouveure et al. | Distance and angular resolutions improvement for a ground-based radar imager | |
| CN113740823B (en) | Moving target signal processing method suitable for airborne multichannel synthetic aperture radar |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |