CN105467373A - Method for estimating physical dimension of conical target of broadband composite bistatic radar - Google Patents

Abstract

The invention discloses a method for estimating the physical dimension of a conical target of a broadband composite bistatic radar, and the method comprises seven steps: 1, building a composite bistatic radar observation model; 2, obtaining a monostatic/bistatic radar one-dimensional ranging image; 3, extracting the position of the scattering center of a monostatic/bistatic radar; 4, solving an intermediate variable through employing a target symmetrical structure; 5, estimating a bistatic angle through employing tracking data; 6, carrying out the combined solving of the height of a cone and the bottom radius; 7, carrying out continuous observation and solving a mean value. The method can directly obtain the physical dimension of an object, is not affected by the attitude of the object, is stable in characteristics, is simple and practical, and facilitates the quick extraction of the features of a slightly moving target.

Description

Method for estimating physical size of cone target of broadband composite bistatic radar

The technical field is as follows:

the invention relates to a method for estimating the physical size of a cone target of a broadband composite bistatic radar, which is based on an electromagnetic scattering theory and a parameter estimation method to obtain the physical size (height and bottom radius) of the cone target. Belonging to the technical field of radar target characteristics.

Background art:

the composite bistatic radar is a radar system which is formed by adding a receiving station on the basis of the existing monostatic radar and can observe two visual angles simultaneously, namely a T/R-R bistatic radar. The cost of a passive receiver is much lower than that of a complete radar, the obtained benefit is very large, the passive receiver has potential advantages of anti-stealth, anti-interference and the like, and information fusion observed through two visual angles can obtain richer and more stable target information, so that the target identification capability of the existing radar is improved.

The broadband radar can obtain a one-dimensional range profile, a two-dimensional Inverse Synthetic Aperture Radar (ISAR) profile and a three-dimensional ISAR profile of a target, the length of the one-dimensional range profile is used for identifying the target, but the length of the one-dimensional range profile is only the projection of the target on the radar sight line, so that the attitude sensitivity is too strong, and the stability is poor; from the ISAR image, more stable structural features can be obtained, but still influenced by the pose of the target. The spatial target is usually a conical structure or a conical-cylindrical combination, and has a typical symmetrical structure, and besides the translational motion of the centroid, the spatial target also has a motion around the centroid (i.e. a micro motion such as precession, nutation and the like), and at present, features of interest to researchers mainly include structural features (shape, size and the like) and micro motion features. The structural characteristics of the target are mainly obtained through a one-dimensional range profile, a two-dimensional ISAR profile and a three-dimensional ISAR profile. The target structural features, particularly the physical dimensions, are obtained through the one-dimensional range profile, the two-dimensional ISAR and the three-dimensional ISAR, and the micro-motion features of the target, such as the precession angular velocity, the precession angle and the like, are generally required to be known, but the estimation of the parameters generally requires the structural features of the target to be known, which constitutes a cyclic problem. The invention provides a method for obtaining the physical dimensions (height and bottom radius) of the targets by adopting the combined observation of the broadband composite bistatic radar and only by single irradiation, and the stable characteristics of the targets can be quickly obtained without knowing the micro-motion parameters of the targets.

The invention content is as follows:

the invention aims to provide a method for estimating the physical size of a cone target of a broadband composite bistatic radar, aiming at solving the problem that the existing monostatic radar is difficult to obtain the physical size of the cone target. According to the method, one-dimensional range profiles of two visual angles are obtained by simultaneously observing a T/R-R composite bistatic radar, a joint equation set is established by utilizing the scattering center position and the symmetry characteristic of a conical target, the height and the bottom surface radius of the conical target are obtained by solving the equation set, and the physical significance is clear.

The technical scheme for realizing the invention is that firstly, a broadband T/R-R composite bistatic radar cone target imaging model is established, single/bistatic one-dimensional range profiles are simultaneously obtained through the T/R-R composite bistatic radar, the single/bistatic scattering center positions corresponding to cone targets are respectively extracted, intermediate variables are respectively estimated by utilizing the symmetry characteristics of the cone targets, then a combined equation set is established by combining bistatic geometric configuration, and the height and the bottom surface radius of the cone targets are obtained through equation set solution.

The invention discloses a method for estimating the physical size of a cone target of a broadband composite bistatic radar, which comprises the following specific steps:

the method comprises the following steps: establishing a composite bistatic radar observation model

And establishing a rectangular coordinate system by taking the center of the bottom surface of the cone target as an origin, and setting the position of the observed monostatic/bistatic scattering center according to the symmetrical characteristic of the target, so as to obtain the monostatic/bistatic one-dimensional range profile radar observation model.

Step two: obtaining one-dimensional range profile of single/double base

And processing the target echo after motion compensation, and obtaining a single/double-base one-dimensional range profile by adopting a super-resolution method.

Step three: extracting monostatic/bistatic scattering center positions

And (3) extracting the scattering centers in the single/double-base one-dimensional range profile by adopting a peak detection method, and respectively constructing equation sets.

Extracting three scattering center position parameters (delta) of the target according to the single-base one-dimensional range profile₁，Δ₂，Δ₃) Three equations can be obtained:

$\left\{\begin{array}{c}{R}_T+{\mathrm{lcos\β}}_T={\mathrm{\Δ}}_1\\ R_T-{\mathrm{lcos\β}}_T={\mathrm{\Δ}}_2\\ R_T-{\mathrm{hsin\β}}_T={\mathrm{\Δ}}_3\end{array}\right.---\left(1\right)$

the symbols in the above formulae are respectively illustrated as follows:

R_Tdistance between T/R station and target centroid, i is cone base radius, h is cone height, β_TIs the pitch angle of the T/R station, Delta₁，Δ₂，Δ₃Respectively, the distances corresponding to the scattering center C, B, A.

Extracting three scattering center position parameters (delta) of the target according to the biprimary one-dimensional range profile₄，Δ₅，Δ₆) Three equations can be obtained:

the symbols in the above formulae are respectively illustrated as follows:

R_Rrespectively the distance between the R station and the target centroid,is the angle ∠ DOT between the T/R station line of sight and the scattering center D position vector,is the angle ∠ DOR, Delta between the R station sight line and the scattering center D position vector₄，Δ₅，Δ₆Bistatic distances corresponding to the scattering center D, E, A, respectively。

Step four: solving intermediate variables using target symmetric structure

The edge scattering centers of the bottom surface of the cone target have symmetry, so that parameters can be offset, and intermediate variables can be solved. Respectively solving intermediate variables (T) by using cone target symmetric structure₁，T₂，T₃，T₄) As follows:

$\left\{\begin{array}{c}{T}_1=\frac{{\mathrm{\Δ}}_1-{\mathrm{\Δ}}_2}{2}\\ T_2=\frac{{\mathrm{\Δ}}_1+{\mathrm{\Δ}}_2-2{\mathrm{\Δ}}_3}{2}\\ T_3=\frac{{\mathrm{\Δ}}_4-{\mathrm{\Δ}}_5}{2}\\ T_2=\frac{{\mathrm{\Δ}}_4+{\mathrm{\Δ}}_5-2{\mathrm{\Δ}}_6}{2}-\frac{{\mathrm{\Δ}}_1+{\mathrm{\Δ}}_2-2{\mathrm{\Δ}}_3}{2}\end{array}\right.---\left(3\right)$

the symbols in the formula are as follows:

T₁，T₂，T₃，T₄four intermediate variables respectively.

Thus, four equations can be derived:

step five: estimating dual-base ground angles using tracking data

Firstly, the distance between a target and a transmitting station and the distance between the target and a receiving station are obtained through tracking; then, a trigonometric relationship is used to obtain a bibase angle estimation value, thereby obtaining an auxiliary equation determined by a spatial angle relationship. The equation is:

cosβ＝sinα_Rcosβ_Tcosβ_R+sinβ_Tsinβ_R(5)

the symbols in the formula are as follows:

β is bipartite base angle, α_RAnd β_RThe azimuth and the pitch angle of the R station sight line are respectively.

Step six: joint solution of cone height and base radius

Combining equations (4) and (5) in step four and step five, the height of the cone and the radius of the bottom surface can be solved.

The bottom surface radius is:

$\tilde{l}=\sqrt{\frac{T_3^2-T_1^2{(1+\frac{T_4}{T_2})}^2}{4{\cos }^2(\mathrm{\β}/2)-{(1+\frac{T_4}{T_2})}^2}}---\left(6\right)$

the height of the cone is:

$\tilde{h}=\frac{T_2\tilde{l}}{\sqrt{{\tilde{l}}^2-T_1^2}}---\left(7\right)$

the symbols in the formula are as follows:bottom surface radius and cone height estimates, respectively.

Step seven: averaging for continuous observation

Through continuous observation and statistical averaging after multiple estimations, higher estimation accuracy can be obtained.

The invention can achieve the following technical effects

1. The invention overcomes the limitation that the existing monostatic radar is not complete in observation information and is difficult to obtain the target physical size in a short time by adding the low-cost receiver, and the method is simple and practical;

2. the method directly obtains the target physical size, is not influenced by the target posture and has stable characteristics;

3. the method can obtain the physical size of the target through single irradiation, has high estimation speed and is beneficial to the characteristic extraction of the quick micro-motion target.

Drawings

FIG. 1 is a general flow diagram of the present invention.

FIG. 2 is a schematic diagram of a cone target bistatic observation model established by the present invention.

FIG. 3a is a single-base one-dimensional range profile obtained by the present invention.

FIG. 3b is a bistatic one-dimensional range profile obtained by the present invention.

FIG. 4a is a graph of the bottom radius error obtained by the present invention.

Fig. 4b is a diagram of the height estimation error obtained by the present invention.

The symbols in the figures are as follows:

o is the origin of coordinates, A is the scattering center corresponding to the vertex of the cone, B, C is the scattering center at the bottom edge observed in the TR station, D, E is the scattering center observed in the R station, R_TDistance between T/R station and target centroid, i is cone base radius, h is cone height, β_TIs a T/R station pitch angle, R_RRespectively the distance between the R station and the target centroid, β is a double base angle, α_RAnd β_RThe azimuth and the pitch angle of the R station sight line are respectively.

Detailed Description

FIG. 1 is a general flow diagram of the present invention. For better understanding of the technical solutions of the present invention, the following further describes embodiments of the present invention with reference to the accompanying drawings.

The method comprises the following steps: establishment of cone target bistatic observation model

As shown in FIG. 2, the T/R station of the single-base radar is located at T_xThe bistatic receiving station R is located at R_xThe height and bottom radius of the rotational symmetric cone target are h and l respectively, the backward scattering property of the rotational symmetric cone target is mainly contributed by three scattering centers (A, B and C), B and C are the intersection points of the plane formed by the T/R station sight line and the target axis and the bottom edge of the cone, the bistatic scattering property of the cone target is mainly contributed by three scattering centers (A, D and E), D and E are the intersection points of the plane formed by the bistatic angular bisector and the target axis and the bottom edge of the cone, and the bistatic angle is represented by β DOT and is represented by β DOTAngle ∠ DOR is shown as

Step two: obtaining a single/double-base one-dimensional range profile of the target echo after the motion compensation is completed by adopting a super-resolution method

The existing broadband radar mostly adopts a mode of alternately transmitting wide-narrow signals, the narrow-band signals are used for tracking targets, and tracking data (information such as distance, speed and the like) are used for motion compensation in broadband imaging. There are many methods for motion compensation, and this patent only considers the target echo processing after the motion compensation is completed.

The method for obtaining the one-dimensional range profile is multiple, and in order to ensure the parameter estimation precision of the invention, a super-resolution method, such as MUSIC, ESPRIT and the like, can be adopted to obtain the super-resolution one-dimensional range profile, thereby improving the accuracy of the subsequent extraction of the scattering center position.

Step three: and extracting scattering centers in the single/double-base one-dimensional range profile, and respectively constructing equation sets.

And respectively extracting the positions of scattering centers with scattering intensity passing a threshold in the single/double-base one-dimensional range profile by adopting a peak detection method. Extracting three scattering center position parameters (delta) of the target according to the single-base one-dimensional range profile₁，Δ₂，Δ₃) Three equations can be obtained:

$\left\{\begin{array}{c}{R}_T+{\mathrm{lcos\β}}_T={\mathrm{\Δ}}_1\\ R_T-{\mathrm{lcos\β}}_T={\mathrm{\Δ}}_2\\ R_T-{\mathrm{hsin\β}}_T={\mathrm{\Δ}}_3\end{array}\right.---\left(8\right)$

the symbols in the formulae are respectively illustrated below:

R_Tdistance between T/R station and target centroid, i is cone base radius, h is cone height, β_TIs the pitch angle of the T/R station, Delta₁，Δ₂，Δ₃Respectively, the distances corresponding to the scattering center C, B, A.

Extracting three scattering center position parameters (delta) of the target according to the biprimary one-dimensional range profile₄，Δ₅，Δ₆) Three equations can be obtained:

the symbols in the formula are as follows:

R_Rrespectively the distance between the R station and the target centroid,is the angle ∠ DOT between the T/R station line of sight and the scattering center D position vector,is the angle ∠ DOR, Delta between the R station sight line and the scattering center D position vector₄，Δ₅，Δ₆The bistatic distances corresponding to the scattering center D, E, A, respectively.

Step four: and respectively solving intermediate variables by using the cone target symmetrical structure to obtain four equations:

the symbols in the formula are as follows:

(T₁，T₂，T₃，T₄) Four intermediate variables are respectively provided, and the other parameters are as above.

Step five: estimating dual-base ground angles using tracking data

The target position can be obtained by tracking, and the double-base earth angle is estimated by combining the known positions of the transmitting station and the receiving station through a trigonometric cosine functionThus constructing another auxiliary equation:

$cos\widetilde{\mathrm{\β}}={\mathrm{sin\α}}_R{\mathrm{cos\β}}_T{\mathrm{cos\β}}_R+{\mathrm{sin\β}}_T{\mathrm{sin\β}}_R---\left(11\right)$

step six: the joint formulas (10) and (11) can solve the equation system to obtain the estimated values of the height and the bottom surface radius of the cone targetIs represented as follows:

$\left\{\begin{array}{c}{\tilde{l}}_i=\sqrt{\frac{T_3^2-T_1^2{(1+\frac{T_4}{T_2})}^2}{4{\cos }^2(\widetilde{\mathrm{\β}}/2)-{(1+\frac{T_4}{T_2})}^2}}\\ {\tilde{h}}_i=\frac{T_2{\tilde{l}}_i}{\sqrt{{\tilde{l}}_i^2-T_1^2}}\end{array}\right.---\left(12\right)$

the symbols in the formula are as follows:

cone height and base radius estimates obtained for a single shot, respectively.

Step seven: through continuous observation, averaging is performed after respective estimation to improve estimation accuracy, and the final estimated values of the cone target height and the bottom surface radius are obtained as follows:

$\left\{\begin{array}{c}\tilde{l}=\frac{1}{N}\underset{N}{\Σ}{\tilde{l}}_i\\ \tilde{h}=\frac{1}{N}\underset{N}{\Σ}{\tilde{h}}_i\end{array}\right.---\left(1\right)$

wherein,the estimated values of the cone height and the bottom surface radius are respectively, and N is the observation frequency.

The effects of the present invention can be illustrated by the following simulation experiments. The simulation parameters are set as follows: the height of the target is 2m, the radius of the bottom surface is 0.5m, the radius of the cone top is 0.05m, three scattering centers are respectively arranged at the edge of the cone top and the edge of the bottom surface, and the scattering coefficient of the cone top scattering center is 0.25m²The scattering coefficients of all scattering centers at the bottom edge are 0.15m²T/R station pitch angle β_T10 °, R station azimuth and pitch angles are β ° respectively_R＝100°，α_RThe bistatic radar one-dimensional range profile is obtained as shown in fig. 3a and 3b, the positions of three scattering centers in the bistatic one-dimensional range profile are extracted as (-2.035, -0.0997, 0.088) m and (-1.677, -0.5513, 0.5279) m, the height of a cone is 2.0663m, the radius of a bottom surface is 0.4969m, and the relative errors are 0.8% and 0.8% respectively, and the relative errors are jointly solved as6 percent. In addition, the adaptability of the method is analyzed by increasing the position estimation error of each scattering center, fig. 4a and 4b respectively show the variation curve of the estimation error along with the position error of the scattering center, and it can be seen that the estimation error gradually increases along with the increase of the position error of the scattering center, and the bottom radius estimation precision is higher, because the bottom radius estimation result is used in the height estimation value, the height estimation precision is slightly poor due to error transfer, but when the position error of the scattering center is less than 0.5m, the estimation relative errors are all less than 10%.

Claims (1)

1. A method for estimating the physical size of a cone target of a broadband composite bistatic radar is characterized by comprising the following steps: the method comprises the following specific steps:

the method comprises the following steps: establishing a composite bistatic radar observation model

Establishing a rectangular coordinate system by taking the center of the bottom surface of the cone target as an origin, and setting the position of the observed monostatic/bistatic scattering center according to the symmetrical characteristic of the target, namely obtaining a monostatic/bistatic one-dimensional range profile radar observation model;

step two: obtaining one-dimensional range profile of single/double base

Processing the target echo after motion compensation, and obtaining a single/double-base one-dimensional range profile by adopting a super-resolution method;

step three: extracting monostatic/bistatic scattering center positions

Extracting scattering centers in the single/double-base one-dimensional range profile by adopting a peak detection method, and respectively constructing equation sets;

extracting three scattering center position parameters (delta) of the target according to the single-base one-dimensional range profile₁，Δ₂，Δ₃) Three equations are obtained:

$\left\{\begin{array}{c}{R}_T+l{\mathrm{cos\β}}_T={\mathrm{\Δ}}_1\\ R_T-l{\mathrm{cos\β}}_T={\mathrm{\Δ}}_2\\ R_T-h{\mathrm{sin\β}}_T={\mathrm{\Δ}}_3\end{array}\right.---\left(1\right)$

the symbols in the formulae are respectively illustrated below:

R_Tdistance between T/R station and target centroid, i is cone base radius, h is cone height, β_TIs the pitch angle of the T/R station, Delta₁，Δ₂，Δ₃Distances corresponding to scattering center C, B, A, respectively;

extracting three scattering center position parameters (delta) of the target according to the biprimary one-dimensional range profile₄，Δ₅，Δ₆) Three equations are obtained:

the symbols in the formulae are respectively illustrated below:

R_Rrespectively the distance between the R station and the target centroid,is the angle ∠ DOT between the T/R station line of sight and the scattering center D position vector,is the angle ∠ DOR, Delta between the R station sight line and the scattering center D position vector₄，Δ₅，Δ₆Bistatic distances corresponding to the scattering center D, E, A, respectively;

step four: solving intermediate variables using target symmetric structure

The edge scattering center of the bottom surface of the cone target has symmetry, so that some parameters are offset, and some intermediate variables are solved; respectively solving intermediate variables (T) by using cone target symmetric structure₁，T₂，T₃，T₄) As follows:

$\left\{\begin{array}{c}{T}_1=\frac{{\mathrm{\Δ}}_1-{\mathrm{\Δ}}_2}{2}\\ T_2=\frac{{\mathrm{\Δ}}_1+{\mathrm{\Δ}}_2-2{\mathrm{\Δ}}_3}{2}\\ T_3=\frac{{\mathrm{\Δ}}_4-{\mathrm{\Δ}}_5}{2}\\ T_4=\frac{{\mathrm{\Δ}}_4+{\mathrm{\Δ}}_5-2{\mathrm{\Δ}}_6}{2}-\frac{{\mathrm{\Δ}}_1+{\mathrm{\Δ}}_2-2{\mathrm{\Δ}}_3}{2}\end{array}\right.---\left(3\right)$

the symbols in the formula are as follows:

T₁，T₂，T₃，T₄respectively four intermediate variables;

thus, four equations are obtained:

step five: estimating dual-base ground angles using tracking data

Firstly, the distance between a target and a transmitting station and the distance between the target and a receiving station are obtained through tracking; then, using the trigonometric relation to obtain the estimated value of the biprimary angle, so as to obtain an auxiliary equation determined by the spatial angle relation, wherein the auxiliary equation is as follows:

cosβ＝sinα_Rcosβ_Tcosβ_R+sinβ_Tsinβ_R(5)

the symbols in the formula are as follows:

β is bipartite base angle, α_RAnd β_RThe azimuth and the pitch angle of the R station sight line are respectively;

step six: joint solution of cone height and base radius

Combining the equations (4) and (5) in the fourth step and the fifth step, and solving to obtain the height of the cone and the radius of the bottom surface;

the bottom surface radius is:

$\tilde{l}=\sqrt{\frac{T_3^2-T_1^2{(1+\frac{T_4}{T_2})}^2}{4{\cos }^2(\mathrm{\β}/2)-{(1+\frac{T_4}{T_2})}^2}}---\left(6\right)$

the height of the cone is:

$\tilde{h}=\frac{T_2\tilde{l}}{\sqrt{{\tilde{l}}^2-T_1^2}}---\left(7\right)$

the symbols in the formula are as follows:respectively, bottom surface radius and cone height estimated values;

step seven: averaging for continuous observation

And through continuous observation and statistical averaging after multiple estimations, higher estimation precision is obtained.