CN112255609A - Constant-acceleration maneuvering target coherent accumulation detection method - Google Patents

Constant-acceleration maneuvering target coherent accumulation detection method Download PDF

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CN112255609A
CN112255609A CN202011096256.9A CN202011096256A CN112255609A CN 112255609 A CN112255609 A CN 112255609A CN 202011096256 A CN202011096256 A CN 202011096256A CN 112255609 A CN112255609 A CN 112255609A
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acceleration
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周共健
许泽宇
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Harbin Institute of Technology
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Harbin Institute of Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • G01S7/415—Identification of targets based on measurements of movement associated with the target

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Abstract

The invention relates to a coherent accumulation detection method for a constant-acceleration maneuvering target, computer equipment and a computer readable storage medium, wherein the method comprises the following steps: radar echo data are obtained, and distance demodulation and pulse compression processing are carried out; determining a search range, a search interval and a discretization numerical value of the search parameter; traversing the corresponding search ranges of all the search parameters, determining a search track for each group of search parameters according to an accurate distance evolution equation of constant Cartesian acceleration motion, extracting target pulse samples and compensating phase fluctuation until the accumulated output of all the search parameters is completed, and obtaining a coherent accumulated output matrix in a parameter space; carrying out constant false alarm rate detection on the coherent accumulation output matrix; and estimating the target motion parameters and outputting target motion traces. The invention provides an accurate distance evolution model of constant Cartesian acceleration motion, and realizes effective coherent accumulation of a constant Cartesian acceleration target, thereby improving detection performance and estimation accuracy.

Description

Constant-acceleration maneuvering target coherent accumulation detection method
Technical Field
The invention relates to the technical field of radar detection, in particular to a coherent accumulation detection method for a constant-acceleration maneuvering target, computer equipment and a computer readable storage medium.
Background
With the rapid development of aerospace technology and stealth technology, how to effectively and accurately realize maneuvering target detection becomes a difficult problem in the field of radar signal processing. In general, long-time coherent accumulation technology can significantly improve the detection performance of the radar on the target. However, during the accumulation time, the complex motion of the motorized target causes range and doppler migration effects, thereby reducing the performance gain of the accumulation technique.
In the last decades, several long-time coherent accumulation detection methods with range migration correction and/or doppler migration compensation have been proposed in succession and used to achieve detection and motion parameter estimation of maneuvering targets. However, existing methods generally consider that the distance between the target and the radar varies with slow time in a polynomial form. Typical methods, such as Radon Fourier Transform (RFT), improved AR and Fractional Fourier Transform (IAR-FRFT), Generalized Radon Fourier Transform (GRFT), consider the equation of the distance between the target and the radar as first, second and third order polynomials over slow time, i.e. assume the target moves at constant radial velocity, radial acceleration, radial jerk relative to the radar over the accumulation time. However, in the real world, common target motions, such as Constant Velocity (CV) motion and Constant Acceleration (CA) motion, cannot be accurately described in a polynomial model under a distance coordinate system. Due to the non-linear relationship between the polar and cartesian coordinate systems, the evolution of the target distance over time is typically a highly non-linear function, the taylor expansion of which may have numerous terms. Due to model mismatch, processing these common target motions using the existing polynomial model-based coherent accumulation method suffers from performance gain degradation, which reduces the detection capability of the radar for the target.
Therefore, in view of the above disadvantages, a coherent accumulation detection method capable of realizing effective accumulation detection and parameter estimation for common constant-acceleration maneuvering target motion is needed.
Disclosure of Invention
The invention aims to provide a long-time coherent accumulation detection method based on an accurate distance evolution model by establishing an accurate distance evolution equation of a target distance along with time aiming at a common uniform acceleration linear motion target in a Cartesian coordinate system.
In order to achieve the above object, the present invention provides a coherent accumulation detection method for a constant acceleration maneuvering target, comprising the following steps:
s1, obtaining radar echo data of the moving target, carrying out discretization processing, carrying out range-direction demodulation and pulse compression processing, finishing intra-pulse energy accumulation, and obtaining a range-slow time two-dimensional data matrix;
s2, initializing the long-time coherent accumulation parameters, and determining the search range, the search interval and the discretization value of the search parameters;
s3, traversing the corresponding search ranges of all search parameters, determining a search track for each group of search parameters according to an accurate distance evolution equation of constant Cartesian acceleration motion, extracting in a distance-slow time two-dimensional data matrix to obtain target pulse samples, compensating phase fluctuation among the pulse samples, accumulating target signal energy through vector addition until the accumulation output of all the search parameters is completed, and obtaining a coherent accumulation output matrix in a parameter space;
s4, giving false alarm probability, carrying out constant false alarm rate detection on the coherent accumulation output matrix, and judging whether a target is detected;
s5, after the target is judged and detected, the target motion parameter estimation is completed according to the peak position coordinates of the target in the parameter space, and the target motion trace is output;
wherein for a target moving with constant Cartesian acceleration, tmThe position coordinate expressions of the target in the Cartesian coordinate system on the X axis and the Y axis at the moment are as follows:
Figure BDA0002723844830000021
in the formula tm＝mTr(M-0, 1.., M-1) represents a slow time, M is the number of accumulated pulses, TrIs the pulse repetition period, x0、vx0And axRespectively, the initial position coordinate, initial velocity and acceleration of the target in the X-axis direction, y0、vy0And ayRespectively setting initial position coordinates, initial speed and acceleration of the target in the Y-axis direction;
the expression of the accurate distance evolution equation of the constant Cartesian acceleration motion is obtained as follows:
Figure BDA0002723844830000031
in the formula, R (t)m) Represents tmThe instantaneous slant distance between the radar and the target at that moment,
Figure BDA0002723844830000032
is the initial distance between the radar and the target,
Figure BDA0002723844830000033
is the initial velocity of the object and is,
Figure BDA0002723844830000034
acceleration of interest, α0Is the angle between the target initial radial velocity and the initial velocity, θ0Is the angle between the initial velocity and acceleration of the target.
Preferably, the transmitting signal adopted by radar observation is a chirp signal, and the expression is as follows:
Figure BDA0002723844830000035
wherein the content of the first and second substances,
Figure BDA0002723844830000036
Figure BDA0002723844830000037
for a fast time, fcFor radar carrier frequency, TpPulse duration, mu is modulation frequency;
the radar echo signal after distance direction demodulation and pulse compression processing has the expression:
Figure BDA0002723844830000038
wherein the content of the first and second substances,
Figure BDA0002723844830000039
A1representing the amplitude of the pulse-compressed signal, c representing the speed of light, B the signal bandwidth, λ the radar wavelength, R (t)m) Represents tmInstantaneous slope distance, t, between radar and target at timem＝mTr(M-0, 1.., M-1) represents a slow time, M is the number of accumulated pulses, TrIn the form of a pulse repetition period,
Figure BDA0002723844830000041
is a time of harmony
Figure BDA0002723844830000042
The corresponding distance.
Preferably, in the step S2, when determining the search range, the search interval and the discretization value of the search parameter, the method includes the following steps:
s2-1, determining search distance, search speed, search acceleration and search range of the first angle, which are respectively expressed as r0min,r0max]、[vmin,vmax]、[amin,amax]、[αmin,αmax]Wherein r is0minAnd r0maxRespectively representing the minimum and maximum search distances, vminAnd vmaxRespectively representing a minimum search speed and a maximum search speed, aminAnd amaxRespectively representing the minimum and maximum search accelerations, alphaminAnd alphamaxRespectively representing a minimum first angle and a maximum first angle, wherein the first angle corresponds to an angle between an initial radial speed and an initial speed of a target;
determining a second angle theta which corresponds to an angle between the initial speed and the acceleration of the target, wherein the value theta of the second angle theta is 0 or pi;
s2-2, determining search distance, search speed and search interval of search acceleration, respectively
Figure BDA0002723844830000043
And
Figure BDA0002723844830000044
wherein c represents the speed of light, λ is the radar wavelength, B is the signal bandwidth, and T is the coherent accumulation time;
determining a search interval delta alpha of the first angle according to prior information and a search range;
s2-3, determining the search distance, the search speed, the search acceleration and the search number of the first angle, wherein the search numbers are respectively expressed as:
Figure BDA0002723844830000045
Figure BDA0002723844830000046
Figure BDA0002723844830000047
Figure BDA0002723844830000051
wherein round (·) represents the rounding operation, and the rounding principle is rounding;
s2-4, obtaining the discretized search distance, the discretized search speed, the discretized search acceleration and the discretized first angle, wherein the discretized search distance, the discretized search speed, the discretized search acceleration and the discretized first angle are respectively expressed as:
Figure BDA0002723844830000055
vj＝vmin+jΔv,j＝0,1,...,Nv-1
ak＝amin+kΔa,k＝0,1,…,Na-1
αq＝αmin+qΔα,q＝0,1,...,Nα-1
completion search parameter (r)0,i,vj,ak,αqθ) setting;
wherein, when the search speed v of the discretizationjWhen the value is 0, the second angle θ is 0.
Preferably, the step S3 further includes:
s3-1, search a group of parameters (r)0,i,vj,ak,αqθ), determining a search trajectory according to an evolution equation of the precise distance of the constant cartesian acceleration motion, wherein the expression is as follows:
Figure BDA0002723844830000052
wherein, r (mT)r) Indicating that the search track has a search parameter of
Figure BDA0002723844830000053
In the case of (1), at tm＝mTrThe skew distance between the time target and the radar;
s3-2, extracting M multiplied by 1 dimension target pulse sample X in the distance-slow time two-dimensional data matrixMThe expression is:
Figure BDA0002723844830000054
wherein s [, ] is a distance-slow time two-dimensional data matrix;
s3-3, compensating phase fluctuation among pulse samples to eliminate Doppler migration, accumulating target signal energy through vector addition, and adopting a coherent accumulation expression of an accurate distance evolution equation based on constant Cartesian acceleration motion as follows:
Figure BDA0002723844830000061
wherein G (r)0,i,vj,ak,αqAnd theta) is expressed when the search parameter is (r)0,i,vj,ak,αqθ) cumulative output;
s3-4, traversing all search parameters, repeating the steps S3-1 to S3-3, and obtaining a coherent accumulation output matrix in the parameter space.
Preferably, when the constant false alarm rate detection is performed in step S4, the expression is:
Figure BDA0002723844830000062
where eta is the adaptive detection threshold, H1Corresponding to the presence of an object, H0The corresponding target does not exist.
Preferably, when the constant false alarm rate detection is performed in step S4, the adaptive detection threshold η is calculated by using a given false alarm probability and reference units around the detection unit.
Preferably, in step S5, when the estimation of the motion parameter of the target is completed according to the peak position coordinate corresponding to the target in the parameter space, the distance, the speed, the acceleration, the angle between the initial radial speed and the initial speed, and the angle between the initial speed and the acceleration corresponding to the detection unit in the parameter space where the target is located are used as the estimation values of the motion parameter of the corresponding target, and the estimation values of the initial radial speed and the initial radial acceleration of the target are obtained:
Figure BDA0002723844830000063
Figure BDA0002723844830000064
wherein
Figure BDA0002723844830000065
Is an estimate of the initial velocity of the vehicle,
Figure BDA0002723844830000066
is an estimate of the acceleration and is,
Figure BDA0002723844830000067
is an estimate of the angle between the initial radial velocity and the initial velocity,
Figure BDA0002723844830000068
is an estimate of the angle between the initial velocity and the acceleration.
Preferably, in step S5, the target motion trace expression is:
Figure BDA0002723844830000071
wherein
Figure BDA0002723844830000072
Is an estimate of the initial distance.
The invention also provides computer equipment which comprises a memory and a processor, wherein the memory stores a computer program, and the processor realizes the steps of the coherent accumulation detection method for the constant acceleration maneuvering target when executing the computer program.
The present invention also provides a computer-readable storage medium having stored thereon a computer program which, when being executed by a processor, carries out the steps of the method for coherent accumulation detection of a maneuvering target for constant acceleration as described in any one of the preceding claims.
The technical scheme of the invention has the following advantages: the invention provides a coherent accumulation detection method for a constant-acceleration maneuvering target, computer equipment and a computer readable storage medium. When the search parameters are matched with the real parameters, the complex range migration and Doppler migration effects in the coherent accumulation process are eliminated, and effective accumulation detection and parameter estimation of common constant Cartesian acceleration moving targets are realized. Compared with the traditional coherent accumulation detection method based on the polynomial approximation motion model, the method is not limited by the accumulation time and the target mobility range because the accurate distance evolution equation without approximation is used. In addition, the invention can provide observation and resolution in velocity and acceleration dimensions in addition to distance and Doppler, and provides additional useful information for subsequent target tracking, data association and the like.
Drawings
FIG. 1 is a step diagram of a coherent accumulation detection method for a constant-acceleration maneuvering target in an embodiment of the invention;
FIG. 2 is a schematic flow chart of a method for detecting coherent accumulation of a constant-acceleration maneuvering target according to an embodiment of the invention;
3(a) to 3(d) are graphs of single-target accumulation results of the coherent accumulation detection method for a constant-acceleration maneuvering target in the embodiment of the invention; wherein, fig. 3(a) is a sectional result diagram of distance and alpha cosine, fig. 3(b) is a sectional result diagram of alpha cosine and acceleration, fig. 3(c) is a sectional result diagram of acceleration and speed, and fig. 3(d) is a sectional result diagram of speed and distance;
FIG. 4(a) is a graph of single target accumulation results for the RFT coherent accumulation detection method;
FIG. 4(b) is a graph of single target accumulation results for a GRFT coherent accumulation detection method;
5(a) to 5(d) show multi-target accumulation results of the constant-acceleration maneuvering target coherent accumulation detection method in the embodiment of the invention; wherein, fig. 5(a) is a graph of multi-target accumulation results of target 1 and target 2, fig. 5(b) is a graph of multi-target accumulation results of target 1 and target 3, fig. 5(c) is a graph of multi-target accumulation results of target 1 and target 4, and fig. 5(d) is a graph of multi-target accumulation results of target 1 and target 5;
FIG. 6 is a graph of the detection performance of the prior GRFT, PRPFT, RFT, MTD methods and the coherent accumulation detection method of the constant acceleration maneuvering target in the embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
As shown in fig. 1 and fig. 2, the method for detecting coherent accumulation of a constant-acceleration maneuvering target provided by the embodiment of the invention specifically includes the following steps:
s1, obtaining radar echo data of the moving target, discretizing the radar echo data, performing range-direction demodulation and pulse compression, completing intra-pulse energy accumulation, and obtaining a range-slow time two-dimensional data matrix.
Coherent radars transmit a transmit signal for observation and receive return echo data. Sampling M groups of echo data to be accumulated, discretizing the sampled data, and extracting a target observation value s in a distance-slow time (pulse) two-dimensional planer(M, N), wherein M denotes an index number of a pulse dimension, M is 0,1,.., M-1, M is the number of accumulated pulses, N denotes an index number of a distance dimension, N is 0,1,..., N-1, N is the number of distance units. And performing range demodulation and pulse compression on the discretized radar echo data to obtain radar echo signals accumulated in the pulses, and expressing the radar echo signals in a matrix form to obtain a range-slow time two-dimensional data matrix for coherent accumulation detection.
Preferably, in the coherent accumulation detection method for a constant-acceleration maneuvering target provided by the invention, a transmission signal adopted by radar observation is a chirp signal, and an expression of the chirp signal is as follows:
Figure BDA0002723844830000091
wherein the content of the first and second substances,
Figure BDA0002723844830000092
Figure BDA0002723844830000093
for a fast time, fcFor radar carrier frequency, TpFor pulse duration, μ is the tuning frequency, exp (-) denotes exponential operation with a natural constant e as base,
Figure BDA0002723844830000094
denotes the imaginary unit symbol and pi denotes the circumferential ratio.
The radar echo signal after distance direction demodulation and pulse compression processing has the expression:
Figure BDA0002723844830000095
wherein the content of the first and second substances,
Figure BDA0002723844830000096
A1representing the amplitude of the pulse-compressed signal, c representing the speed of light, B the signal bandwidth, λ the radar wavelength, R (t)m) Represents tmInstantaneous slope distance, t, between radar and target at timem＝mTr(M-0, 1.., M-1) represents a slow time, M is the number of accumulated pulses, TrIn the form of a pulse repetition period,
Figure BDA0002723844830000097
is a time of harmony
Figure BDA0002723844830000098
The corresponding distance. Expressed in matrix form as s [, ]]。
And S2, initializing the long-time coherent accumulation parameters, and determining the search range, the search interval and the discretization value of the search parameters.
The search parameter includes a search distance r0The target tracking device comprises a target, a search speed v, a search acceleration a, a first angle alpha and a second angle theta, wherein the first angle alpha corresponds to an angle between an initial radial speed and an initial speed of the target, and the second angle theta corresponds to an angle between an initial speed and an acceleration of the target.
S3, traversing the corresponding search ranges of all search parameters, determining the search track of each group of search parameters according to the accurate distance evolution equation of constant Cartesian acceleration motion, extracting in a distance-slow time two-dimensional data matrix to obtain target pulse samples, compensating phase fluctuation among the pulse samples, accumulating target signal energy through vector addition until the accumulation output of all the search parameters is completed, and obtaining a coherent accumulation output matrix in a parameter space.
Step S3 is directed to performing coherent accumulation processing based on the precise distance evolution model, traversing all search parameters to obtain an accumulated output. When a target is present, the search parameters spike at a location closest to the target.
Assuming a target with constant Cartesian acceleration (a) within the radar detection areax,ay) From position (x) at an initial moment0,y0) Moving, the radar observes the target at the origin of coordinates (0, 0).
According to the assumption of constant Cartesian acceleration motion, tmThe position coordinates of the target in the X axis and the Y axis at the moment are as follows:
Figure BDA0002723844830000101
wherein x0、vx0And axRespectively, the initial position coordinate, initial velocity and acceleration of the target in the X-axis direction, y0、vy0And ayThe initial position coordinates, initial velocity and acceleration of the target in the Y-axis direction, respectively.
Is obtained at tmAt the moment, the expression of an evolution equation of the accurate distance between the radar and the target is as follows:
Figure BDA0002723844830000102
wherein R (t)m) Represents tmThe instantaneous slant distance between the radar and the target at that moment,
Figure BDA0002723844830000103
is the initial distance between the radar and the target,
Figure BDA0002723844830000111
is the initial velocity of the object and is,
Figure BDA0002723844830000112
acceleration of interest, α0(α0∈[0,π]) Is the angle between the target initial radial velocity and the initial velocity, θ0Is the angle between the initial velocity and acceleration of the target. Generally, a uniform acceleration motion in a cartesian coordinate system is described as a linear motion with a constant acceleration, so that an angle θ between an initial velocity of an object and the acceleration0Involving only two cases, i.e. theta 00 or theta0＝π。
The coherent accumulation of the exact distance evolution equation based on constant cartesian acceleration motion can be expressed as:
Figure BDA0002723844830000113
wherein T is the coherent accumulation time, r0Representing a search distance, v representing a search velocity, a representing a search acceleration, alpha representing an angle between an initial radial velocity and an initial velocity, theta representing an angle between the initial velocity and the acceleration, s (,) representing a radar echo signal after pulse compression, and G (r)0V, a, α, θ) is given as (r) in the input search parameter0V, a, α, θ).
And S4, giving false alarm probability, carrying out constant false alarm rate detection on the coherent accumulation output matrix, and judging whether a target is detected.
And S5, after the target is judged and detected, finishing target motion parameter estimation according to the corresponding peak position coordinates of the target in the parameter space, and outputting a target motion trace point.
The coherent accumulation detection method for the constant-acceleration maneuvering target provides a new way for effectively detecting the common constant-Cartesian-acceleration moving target. The coherent accumulation detection method disclosed by the invention uses the accurate distance evolution model to replace an approximate polynomial model, and calculation based on Taylor expansion is not needed, so that the method can effectively accumulate energy of invariant of a target under feasible calculation complexity, and coherent accumulation detection is realized.
Preferably, in step S2, when determining the search range, the search interval, and the discretization value of the search parameter, the method specifically includes the following steps:
s2-1, determining search distance r0Search ranges of the search speed v, the search acceleration a, the first angle alpha and the second angle theta.
Search distance r of target to be searched0Search ranges of the search velocity v, the search acceleration a, and the first angle α are respectively represented as [ r0min,r0max]、[vmin,vmax]、[amin,amax]And [ alpha ]min,αmax]Wherein r is0minAnd r0maxRespectively representing the minimum and maximum search distances, vminAnd vmaxRespectively representing a minimum search speed and a maximum search speed, aminAnd amaxRespectively representing the minimum and maximum search accelerations, alphaminAnd alphamaxRespectively representing a minimum first angle and a maximum first angle.
It should be noted that, unlike the other four parameters, the second angle θ takes two different values, that is, θ ═ 0 or θ ═ pi.
The search range of the search parameters may be determined based on radar observations, as well as some a priori information and motion characteristics of the target.
S2-2, determining search distance r0Search intervals of the search velocity v and the search acceleration a are respectively expressed as
Figure BDA0002723844830000121
And
Figure BDA0002723844830000122
where c represents the speed of light, λ is the radar wavelength, B is the signal bandwidth, and T is the coherent integration time.
Easy-to-know radar distance resolution unit
Figure BDA0002723844830000123
Doppler resolution unit
Figure BDA0002723844830000124
After radar system parameter determination, search for distance r0Search intervals of the search velocity v and the search acceleration a may be determined as
Figure BDA0002723844830000125
And
Figure BDA0002723844830000126
the search interval Δ α for the first angle α to be searched can be determined according to the prior information and the search range. Preferably, if the relevant prior information of the parameter is known, a narrow-range fine search can be performed, that is, it is determined from the prior information that a narrow search range (non-full range [0, pi ]) exists for the first angle α]) Search interval Δ α is in the interval [10 ]-3，10-4]If no relevant prior information is available, the search range of the first angle α is the full range [0, π]Then the whole range [0, π ] can be proceeded]In the interval [10 ]-1，10-2]And (4) the following steps.
S2-3, determining the search distance r0The search speed v, the search acceleration a, and the search number of the first angle α are respectively expressed as:
Figure BDA0002723844830000131
Figure BDA0002723844830000132
Figure BDA0002723844830000133
Figure BDA0002723844830000134
where round (·) denotes the rounding operation, the rounding principle is rounding, i.e. taking the integer nearest to the real number in parentheses.
S2-4, obtaining the discretization search distance r0,iDiscretized search velocity vjDiscretized search acceleration akDiscretized first angle alphaqAnd can be respectively expressed as:
Figure BDA0002723844830000137
vj＝vmin+jΔv,j＝0,1,...,Nv-1
ak＝amin+kΔa,k＝0,1,...,Na-1
αq＝αmin+qΔα,q＝0,1,...,Nα-1
completion search parameter (r)0,i,vj,ak,αqAnd theta) setting.
In particular, when the search velocity v is discretizedjWhen the value is 0, the second angle θ is only 0. Since in this case the speed and acceleration of the object must then be in the same direction.
Preferably, the step S3 further includes:
s3-1, searching in a groupCable parameter (r)0,i,vj,ak,αqAnd theta), the search track of the motion accurate distance evolution model based on the constant Cartesian acceleration is expressed as follows:
Figure BDA0002723844830000135
wherein, r (mT)r) Indicating that the search track has a search parameter of
Figure BDA0002723844830000136
In the case of (1), at tm＝mTrThe skew between the target and the radar at that time.
S3-2, extracting M multiplied by 1 dimension target pulse sample X from the distance-slow time two-dimensional data matrix obtained in the step S1 according to the searching track determined in the step S3-1MThe expression is:
Figure BDA0002723844830000141
where s [, ] is the distance-slow time two-dimensional data matrix after pulse compression. If and only if the search parameters are consistent with the actual motion parameters of the target, the signal energy on the distance-slow time (pulse) plane along the actual target motion point trace can be extracted, thereby eliminating the highly nonlinear distance migration effect caused by the moving target in the accumulation process.
S3-3, compensating phase fluctuation among pulse samples to eliminate Doppler migration, accumulating target signal energy through vector addition, and adopting a coherent accumulation expression of an accurate distance evolution equation based on constant Cartesian acceleration motion as follows:
Figure BDA0002723844830000142
wherein G (r)0,i,vj,ak,αqAnd theta) is expressed when the search parameter is (r)0,i,vj,ak,αqAnd θ) the accumulated output.
S3-4, traversing all search parameters, repeating the steps S3-1 to S3-3, and obtaining a coherent accumulation output matrix in the parameter space. The coherent accumulation output matrix represents the accumulation output corresponding to each group of search parameters in a matrix form.
Preferably, in step S4, when detecting the constant false alarm rate, the coherent accumulation output amplitude | G (r) of the detection unit is obtained0,i,vj,ak,αqθ) | is used as a detection statistic and is compared with a self-adaptive detection threshold under a given false alarm probability, and the expression is as follows:
Figure BDA0002723844830000151
where eta is the adaptive detection threshold, H1Corresponding to the presence of an object, H0The corresponding target does not exist. When coherent accumulation output amplitude | G (r) of the detection unit0,i,vj,ak,αqTheta) is higher than the adaptive detection threshold, the target is judged to be detected; otherwise, the target is judged not to be detected.
Further, the adaptive detection threshold η may be calculated by a given false alarm probability and reference units around the detection unit. The specific position of the reference unit and the specific process of the constant false alarm rate detection may refer to the prior art, and are not further described herein.
Preferably, in step S5, when the estimation of the motion parameter of the target is completed according to the peak position coordinate corresponding to the target in the parameter space, the distance, the speed, the acceleration, the angle between the initial radial speed and the initial speed, and the angle between the initial speed and the acceleration corresponding to the detection unit in the parameter space where the target is located are used as the estimation values of the motion parameter of the corresponding target, and the estimation value of the initial radial speed of the target is obtained
Figure BDA0002723844830000152
And an estimate of the initial radial acceleration
Figure BDA0002723844830000153
Figure BDA0002723844830000154
Figure BDA0002723844830000155
Wherein
Figure BDA0002723844830000156
Is an estimate of the initial velocity of the target,
Figure BDA0002723844830000157
is an estimate of the acceleration of the target,
Figure BDA0002723844830000158
is an estimate of the angle between the initial radial velocity and the initial velocity,
Figure BDA0002723844830000159
is an estimate of the angle between the initial velocity and the acceleration.
Further, in step S5, the motion point trace of the target is estimated by taking the corresponding search curve as the motion point trace of the target, and the target motion point trace is obtained by the following expression:
Figure BDA00027238448300001510
wherein
Figure BDA00027238448300001511
Is an estimate of the initial distance of the target.
As shown in fig. 3(a) to fig. 6, the performance of the coherent accumulation detection method for a constant-acceleration maneuvering target provided by the present invention is verified by combining with a simulation test, and the coherent accumulation detection method provided by the present invention (referred to as the present method for short) is compared with some typical coherent accumulation detection methods in the prior art, including a Radon fourier transform method (referred to as an RFT method for short), a generalized Radon fourier transform method (referred to as a GRFT method for short), a polynomial Radon-polynomial fourier transform method (referred to as a PRPFT method for short), and a maneuvering target detection method (referred to as an MTD method for short).
Fig. 3(a) to 3(d) are graphs of single-target accumulation results of the target coherent accumulation detection method of the present invention. In order to clearly display the accumulation condition of the target coherent accumulation detection method in the parameter space, accumulation result graphs of the target in a distance and alpha cosine tangent plane, an alpha cosine and acceleration tangent plane, an acceleration and speed tangent plane and a speed and distance tangent plane are respectively given, wherein alpha represents the included angle between the initial radial speed and the initial speed of the target. Fig. 3(a) is a sectional result graph of distance and alpha cosine, fig. 3(b) is a sectional result graph of alpha cosine and acceleration, fig. 3(c) is a sectional result graph of acceleration and velocity, and fig. 3(d) is a sectional result graph of velocity and distance.
For comparison, fig. 4 shows graphs of single-target accumulation results of two typical coherent accumulation detection methods, fig. 4(a) is a graph of accumulation results of the RFT coherent accumulation detection method, and fig. 4(b) is a graph of accumulation results of the GRFT coherent accumulation detection method. The advantage of the method on the single-target coherent accumulation result can be clearly seen from fig. 3(a) to 4 (b).
As shown in fig. 5(a) to 5(d), in one specific embodiment, there are five targets in the radar observation scene, which are denoted as target 1, target 2, target 3, target 4 and target 5, respectively, for convenience of description, where target 2 has a different distance from target 1, target 3 has a different radial velocity from target 1, target 4 has a different acceleration from target 1, and target 5 has a different velocity from target 1. FIG. 5(a) is a graph of multiple target accumulation for targets 1 and 2, FIG. 5(b) is a graph of multiple target accumulation for targets 1 and 3, FIG. 5(c) is a graph of multiple target accumulation for targets 1 and 4, and FIG. 5(d) is a graph of multiple target accumulation for targets 1 and 5. It can be seen that the method provided by the invention can realize effective coherent accumulation and detection of multiple targets.
Fig. 6 is a detection probability curve of the coherent accumulation detection method of the present invention and some typical coherent accumulation detection methods, and it can be seen that when the detection probability is required to reach a certain specific value, the input signal-to-noise ratio required by the method is always lower than that of other coherent accumulation detection methods. The method can obtain the best detection performance.
The above content results prove the superiority of the target coherent accumulation detection method in the aspects of coherent accumulation gain, multi-target accumulation performance and detection performance. Meanwhile, compared with the existing typical coherent accumulation detection method, the method is not limited by accumulation time, target distance and target speed range due to the accurate matching of the accurate distance evolution model. In addition, the method can provide observation and resolution in velocity and acceleration dimensions in addition to distance and Doppler, and provides additional useful information for subsequent target tracking, data association and the like.
In particular, in some preferred embodiments of the present invention, there is further provided a computer device, including a memory and a processor, where the memory stores a computer program, and the processor implements the steps of the coherent accumulation detection method for a constant acceleration maneuvering target in any of the above embodiments when executing the computer program.
In other preferred embodiments of the present invention, a computer-readable storage medium is further provided, on which a computer program is stored, and the computer program is executed by a processor to implement the steps of the coherent accumulation detection method for a constant acceleration maneuvering target described in any of the above embodiments.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the coherent accumulation detection method for constant acceleration maneuver targets, and will not be described repeatedly herein.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. A coherent accumulation detection method for a constant-acceleration maneuvering target is characterized by comprising the following steps:
s1, obtaining radar echo data of the moving target, carrying out discretization processing, carrying out range-direction demodulation and pulse compression processing, finishing intra-pulse energy accumulation, and obtaining a range-slow time two-dimensional data matrix;
s2, initializing the long-time coherent accumulation parameters, and determining the search range, the search interval and the discretization value of the search parameters;
s3, traversing the corresponding search ranges of all search parameters, determining a search track for each group of search parameters according to an accurate distance evolution equation of constant Cartesian acceleration motion, extracting in a distance-slow time two-dimensional data matrix to obtain target pulse samples, compensating phase fluctuation among the pulse samples, accumulating target signal energy through vector addition until the accumulation output of all the search parameters is completed, and obtaining a coherent accumulation output matrix in a parameter space;
s4, giving false alarm probability, carrying out constant false alarm rate detection on the coherent accumulation output matrix, and judging whether a target is detected;
s5, after the target is judged and detected, the target motion parameter estimation is completed according to the peak position coordinates of the target in the parameter space, and the target motion trace is output;
wherein for a target moving with constant Cartesian acceleration, tmThe position coordinate expressions of the target in the Cartesian coordinate system on the X axis and the Y axis at the moment are as follows:
Figure FDA0002723844820000011
in the formula tm＝mTr(M-0, 1.., M-1) represents a slow time, M is the number of accumulated pulses, TrIs the pulse repetition period, x0、vx0And axRespectively, the initial position coordinate, initial velocity and acceleration of the target in the X-axis direction, y0、vy0And ayRespectively setting initial position coordinates, initial speed and acceleration of the target in the Y-axis direction;
the expression of the accurate distance evolution equation of the constant Cartesian acceleration motion is obtained as follows:
Figure FDA0002723844820000021
in the formula, R (t)m) Represents tmThe instantaneous slant distance between the radar and the target at that moment,
Figure FDA0002723844820000022
is the initial distance between the radar and the target,
Figure FDA0002723844820000023
is the initial velocity of the object and is,
Figure FDA0002723844820000024
acceleration of interest, α0Is the angle between the target initial radial velocity and the initial velocity, θ0Is the angle between the initial velocity and acceleration of the target.
2. The coherent accumulation detection method for a constant-acceleration maneuvering target according to claim 1, characterized by comprising:
the transmitting signal adopted by radar observation is a linear frequency modulation pulse signal, and the expression is as follows:
Figure FDA0002723844820000025
wherein the content of the first and second substances,
Figure FDA0002723844820000026
Figure FDA0002723844820000027
for a fast time, fcFor radar carrier frequency, TpPulse duration, mu is modulation frequency;
the radar echo signal after distance direction demodulation and pulse compression processing has the expression:
Figure FDA0002723844820000028
wherein the content of the first and second substances,
Figure FDA0002723844820000029
A1representing the amplitude of the pulse-compressed signal, c representing the speed of light, B the signal bandwidth, λ the radar wavelength, R (t)m) Represents tmInstantaneous slope distance, t, between radar and target at timem＝mTr(M-0, 1.., M-1) represents a slow time, M is the number of accumulated pulses, TrIn the form of a pulse repetition period,
Figure FDA00027238448200000210
is a time of harmony
Figure FDA00027238448200000211
The corresponding distance.
3. The coherent accumulation detection method for a constant-acceleration maneuvering target according to claim 1, characterized by comprising:
in step S2, when determining the search range, the search interval, and the discretization value of the search parameter, the method includes the following steps:
s2-1, determining search distance, search speed, search acceleration and search range of the first angle, which are respectively expressed as r0min,r0max]、[vmin,vmax]、[amin,amax]、[αmin,αmax]Wherein r is0minAnd r0maxRespectively representing the minimum and maximum search distances, vminAnd vmaxRespectively representing a minimum search speed and a maximum search speed, aminAnd amaxRespectively representing the minimum and maximum search accelerations, alphaminAnd alphamaxRespectively representing a minimum first angle and a maximum first angle, wherein the first angle alpha corresponds to an angle between an initial radial speed and an initial speed of a target;
determining a second angle theta which corresponds to an angle between the initial speed and the acceleration of the target, wherein the value theta of the second angle theta is 0 or pi;
s2-2, determining search distance, search speed and search interval of search acceleration, respectively
Figure FDA0002723844820000031
And
Figure FDA0002723844820000032
wherein c represents the speed of light, λ is the radar wavelength, B is the signal bandwidth, and T is the coherent accumulation time;
determining a search interval delta alpha of the first angle according to prior information and a search range;
s2-3, determining the search distance, the search speed, the search acceleration and the search number of the first angle, wherein the search numbers are respectively expressed as:
Figure FDA0002723844820000033
Figure FDA0002723844820000034
Figure FDA0002723844820000035
Figure FDA0002723844820000036
wherein round (·) represents the rounding operation, and the rounding principle is rounding;
s2-4, obtaining the discretized search distance, the discretized search speed, the discretized search acceleration and the discretized first angle, wherein the discretized search distance, the discretized search speed, the discretized search acceleration and the discretized first angle are respectively expressed as:
Figure FDA0002723844820000044
vj＝vmin+jΔv,j＝0,1,...,Nv-1
ak＝amin+kΔa,k＝0,1,...,Na-1
αq＝αmin+qΔα,q＝0,1,...,Nα-1
completion search parameter (r)0,i,vj,ak,αqθ) setting;
wherein, when the search speed v of the discretizationjWhen the value is 0, the second angle θ is 0.
4. A constant-acceleration maneuvering target coherent accumulation detection method according to claim 3, characterized by,
the step S3 further includes:
s3-1, search a group of parameters (r)0,i,vj,ak,αqθ), determining a search trajectory according to an evolution equation of the precise distance of the constant cartesian acceleration motion, wherein the expression is as follows:
Figure FDA0002723844820000041
wherein, r (mT)r) Indicating that the search track has a search parameter of
Figure FDA0002723844820000042
In the case of (1), at tm＝mTrThe skew distance between the time target and the radar;
s3-2, extracting M multiplied by 1 dimension target pulse sample X in the distance-slow time two-dimensional data matrixMThe expression is:
Figure FDA0002723844820000043
wherein s [, ] is a distance-slow time two-dimensional data matrix;
s3-3, compensating phase fluctuation among pulse samples to eliminate Doppler migration, accumulating target signal energy through vector addition, and adopting a coherent accumulation expression of an accurate distance evolution equation based on constant Cartesian acceleration motion as follows:
Figure FDA0002723844820000051
wherein G (r)0,i,vj,ak,αqAnd theta) is expressed when the search parameter is (r)0,i,vj,ak,αqθ) cumulative output;
s3-4, traversing all search parameters, repeating the steps S3-1 to S3-3, and obtaining a coherent accumulation output matrix in the parameter space.
5. A constant-acceleration maneuvering target coherent accumulation detection method according to claim 4, characterized by,
when the constant false alarm rate detection is performed in step S4, the expression is:
Figure FDA0002723844820000052
where eta is the adaptive detection threshold, H1Corresponding to the presence of an object, H0The corresponding target does not exist.
6. The coherent accumulation detection method for a constant-acceleration maneuvering target according to claim 5, characterized by comprising:
when the constant false alarm rate detection is performed in step S4, the adaptive detection threshold η is calculated by the given false alarm probability and the reference units around the detection unit.
7. The coherent accumulation detection method for a constant-acceleration maneuvering target according to claim 4, characterized by comprising:
in step S5, when the estimation of the motion parameter of the target is completed according to the peak position coordinate corresponding to the target in the parameter space, the distance, the speed, the acceleration, the angle between the initial radial speed and the initial speed, and the angle between the initial speed and the acceleration corresponding to the detection unit in the parameter space where the target is located are used as the estimation values of the motion parameter of the corresponding target, and the estimation values of the initial radial speed and the initial radial acceleration of the target are obtained:
Figure FDA0002723844820000061
Figure FDA0002723844820000062
wherein
Figure FDA0002723844820000063
Is an estimate of the initial velocity of the vehicle,
Figure FDA0002723844820000064
is an estimate of the acceleration and is,
Figure FDA0002723844820000065
is an estimate of the angle between the initial radial velocity and the initial velocity,
Figure FDA0002723844820000066
is an estimate of the angle between the initial velocity and the acceleration.
8. The coherent accumulation detection method for a constant-acceleration maneuvering target according to claim 7, characterized by comprising:
in step S5, the target motion trace expression is:
Figure FDA0002723844820000067
wherein
Figure FDA0002723844820000068
Is an estimate of the initial distance.
9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor, when executing the computer program, implements the steps of the constant acceleration maneuver target coherent accumulation detection method according to any one of claims 1 to 8.
10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method for coherent accumulation detection of a maneuvering target with constant acceleration according to any one of claims 1 to 8.
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