1. A method for estimating the attitude of a spin space target is characterized by comprising the following steps:

acquiring a plurality of first echo signals in a preset time period through a plurality of ISAR radar systems, and performing range-Doppler processing on the first echo signals to obtain a first radar image sequence of a target area, wherein the first radar image sequence comprises a plurality of ISAR observation images;

extracting two target projection length characteristic structures from each ISAR observation image, and determining a target distance dimension size of the target projection length characteristic structures in a distance dimension and a target Doppler dimension size in a Doppler dimension;

acquiring a first pitch angle and a first azimuth angle corresponding to each ISAR observation image, and determining a central radar sight direction vector of each ISAR radar system according to the first pitch angle and the first azimuth angle;

constructing a first optimization model according to the target distance dimension and the central radar sight direction vector, and solving the first optimization model by utilizing a particle swarm algorithm to obtain a target instantaneous attitude parameter;

and constructing a second optimization model according to the target Doppler dimension and the target instantaneous attitude parameters, solving the second optimization model by using a particle swarm algorithm to obtain target spin parameters, and further finishing attitude estimation on the spin space target according to the target instantaneous attitude parameters and the target spin parameters.

2. The method of claim 1, wherein the central radar line-of-sight vector is calculated by the following formula:

wherein the content of the first and second substances,representing the central radar line-of-sight vector, θ (t)_m) Denotes a first pitch angle, phi (t)_m) Denotes a first azimuth angle, t_mThe central time of the coherent integration time of the ISAR observed image is shown.

3. The method of claim 1, wherein the first optimization model comprises a first objective function and a first constraint, and the first objective function is:

wherein the content of the first and second substances,p represents ISAR radarNumber of systems, α_nAnd beta_nRepresenting instantaneous attitude parameters, R, of the object to be solved_n,pRepresenting the target distance dimension L of the n-th target projection length feature structure in the p-th ISAR observation image_nRepresenting the true size of the nth target projection length feature,representing a central radar sight direction vector of the ISAR radar system corresponding to the p-th ISAR observation image;

the first constraint condition is as follows:

tanα₁tanα₂+cos(β₁-β₂)＝0

wherein alpha is₁、α₂、β₁And beta₂Representing the instantaneous attitude parameters of the target to be solved.

4. The method of claim 1, wherein the step of solving the first optimization model by using a particle swarm algorithm to obtain the target instantaneous attitude parameter specifically comprises:

setting the shortest moving distance, and randomly generating a first particle swarm in a feasible region of the first optimization model, wherein the feasible solution of the first particle swarm is a first individual position;

searching according to the first cost function to obtain the current optimal position of the particles and the optimal position of the particle swarm;

after adjusting the particle position in the first particle swarm, updating the current optimal particle position and the current optimal particle swarm position until the maximum iteration step number or the minimum change criterion is met;

and determining the target instantaneous attitude parameter according to the current optimal first individual position.

5. The method of claim 1, wherein the second optimization model comprises a second objective function, and the second objective function is:

wherein the content of the first and second substances,

n∈[1,2],p∈[1,P]p denotes the number of ISAR radar systems, θ_rot、φ_rotAnd ω_rotRepresenting the spin parameters of the object to be solved,represents preset radar line-of-sight parameters,represents the central radar sight direction vector, D, of the ISAR radar system corresponding to the p-th ISAR observation image_n,pAnd the target Doppler dimension of the characteristic structure of the projection length of the nth target in the p ISAR observation image is shown.

6. The method for estimating the attitude of a spin space object according to claim 1, wherein the step of solving the second optimization model by using a particle swarm algorithm to obtain the spin parameters of the object specifically comprises:

setting the shortest moving distance, and randomly generating a second particle swarm in the feasible region of the second optimization model, wherein the feasible solution of the second particle swarm is a second individual position;

searching according to the second cost function to obtain the current optimal position of the particles and the optimal position of the particle swarm;

after adjusting the position of the particles in the second particle swarm, updating the current optimal position of the particles and the optimal position of the particle swarm until the maximum iteration step number or the minimum change criterion is met;

and determining the target spin parameter according to the current optimal second body position.

7. A spin space object pose estimation method according to any of claims 1 to 6, wherein pose estimation for a spin space object is done according to the following formula:

wherein the content of the first and second substances,andrepresenting the characteristic attitude, alpha, of the object in spin space₁、α₂、β₁And beta₂Representing the instantaneous attitude parameters of the target,representing the rotation vector of the object in spin space, theta_rot、φ_rotAnd ω_rotRepresenting the target spin parameters.

8. A spin space object pose estimation system, comprising:

the first radar image sequence acquisition module is used for acquiring a plurality of first echo signals in a preset time period through a plurality of ISAR radar systems and performing range-Doppler processing on the first echo signals to obtain a first radar image sequence of a target area, wherein the first radar image sequence comprises a plurality of ISAR observation images;

a target distance dimension size and target doppler dimension size determination module, configured to extract two target projection length feature structures from each ISAR observation image, and determine a target distance dimension size of the target projection length feature structure in a distance dimension and a target doppler dimension size in a doppler dimension;

the central radar sight direction vector determining module is used for acquiring a first pitch angle and a first azimuth angle corresponding to each ISAR observation image and determining the central radar sight direction vector of each ISAR radar system according to the first pitch angle and the first azimuth angle;

the target instantaneous attitude parameter determining module is used for constructing a first optimization model according to the target distance dimension and the central radar sight direction vector, and solving the first optimization model by utilizing a particle swarm algorithm to obtain a target instantaneous attitude parameter;

and the target spin parameter determining module is used for constructing a second optimization model according to the target Doppler dimension size and the target instantaneous attitude parameter, solving the second optimization model by using a particle swarm algorithm to obtain a target spin parameter, and further finishing attitude estimation on the spin space target according to the target instantaneous attitude parameter and the target spin parameter.

9. An apparatus for estimating the attitude of a target in spin space, comprising:

at least one processor;

at least one memory for storing at least one program;

when executed by the at least one processor, cause the at least one processor to implement a method of estimating the attitude of a spin space object as claimed in any one of claims 1 to 7.

10. A computer readable storage medium in which a processor-executable program is stored, the processor-executable program when executed by a processor being for performing a method of estimating an attitude of a spin space object as claimed in any one of claims 1 to 7.

Background

The spin space target instantaneous state estimation has very important significance for knowing the in-orbit running state of the spin space target and judging the aerospace development situation of the spin space target. The technology for accurately obtaining the absolute attitude of an important load component of a space target and the overall motion rule of the space target by using an image obtained by measuring the space target by using an Inverse Synthetic Aperture Radar (ISAR) can be practically applied to civil and military fields including space target fault rescue, threat degree evaluation and the like, and is a practical technology capable of realizing the on-orbit state estimation of a spinning space target at present.

Currently, there are two main ways to determine the on-orbit state of a spin space target: firstly, the distance change of a pyramid reflector equipped for a space target is measured through a laser sensor so as to determine the on-orbit running state of the target, secondly, the state parameters of a 3D model of the target are set to generate a 2D radar image, and the on-orbit state of the target is determined according to the approximation degree between the radar image and the target image obtained by observation. However, most of the existing schemes rely on strong prior conditions such as an accumulated database or azimuth calibration, and the influence of target spin on the observation characteristics is rarely parameterized and modeled. Thus, these data-driven algorithms are difficult to apply to non-cooperative targets in the absence of these observation priors, and have limitations in actual spatial target attitude measurements.

Disclosure of Invention

The present invention aims to solve at least to some extent one of the technical problems existing in the prior art.

Therefore, an object of an embodiment of the present invention is to provide a method for estimating a spin space target attitude, where the method performs range-doppler processing after synchronizing radar echo signals obtained by multi-station observation in a preset time period to obtain a multi-frame synchronized ISAR observation image, then extracts projection size parameters of a target in a range direction and a doppler direction from the obtained multi-frame ISAR observation image, establishes two independent optimization models in combination with observation geometric parameters of each ISAR radar system, and uses a particle swarm optimization method to sequentially solve an instantaneous attitude parameter and a spin parameter of a spin space target, thereby completing attitude estimation of the spin space target.

It is another object of an embodiment of the present invention to provide a spin space object attitude estimation system.

In order to achieve the technical purpose, the technical scheme adopted by the embodiment of the invention comprises the following steps:

in a first aspect, an embodiment of the present invention provides a method for estimating an attitude of a spin space target, including the following steps:

acquiring a plurality of first echo signals in a preset time period through a plurality of ISAR radar systems, and performing range-Doppler processing on the first echo signals to obtain a first radar image sequence of a target area, wherein the first radar image sequence comprises a plurality of ISAR observation images;

extracting two target projection length characteristic structures from each ISAR observation image, and determining a target distance dimension size of the target projection length characteristic structures in a distance dimension and a target Doppler dimension size in a Doppler dimension;

acquiring a first pitch angle and a first azimuth angle corresponding to each ISAR observation image, and determining a central radar sight direction vector of each ISAR radar system according to the first pitch angle and the first azimuth angle;

constructing a first optimization model according to the target distance dimension and the central radar sight direction vector, and solving the first optimization model by utilizing a particle swarm algorithm to obtain a target instantaneous attitude parameter;

and constructing a second optimization model according to the target Doppler dimension and the target instantaneous attitude parameters, solving the second optimization model by using a particle swarm algorithm to obtain target spin parameters, and further finishing attitude estimation on the spin space target according to the target instantaneous attitude parameters and the target spin parameters.

Further, in an embodiment of the present invention, the calculation formula of the central radar sight line direction vector is:

wherein the content of the first and second substances,representing the central radar line-of-sight vector, θ (t)_m) Denotes a first pitch angle, phi (t)_m) Denotes a first azimuth angle, t_mThe central time of the coherent integration time of the ISAR observed image is shown.

Further, in an embodiment of the present invention, the first optimization model includes a first objective function and a first constraint, and the first objective function is:

wherein the content of the first and second substances,n∈[1，2]，p∈[1，P]p denotes the number of ISAR radar systems, α_nAnd beta_nRepresenting instantaneous attitude parameters, R, of the object to be solved_n，pRepresenting the target distance dimension L of the n-th target projection length feature structure in the p-th ISAR observation image_nRepresenting the true size of the nth target projection length feature,representing a central radar sight direction vector of the ISAR radar system corresponding to the p-th ISAR observation image;

the first constraint condition is as follows:

tanα₁tanα₂+cos(β₁-β₂)＝0

wherein alpha is₁、α₂、β₁And beta₂Representing the instantaneous attitude parameters of the target to be solved.

Further, in an embodiment of the present invention, the step of solving the first optimization model by using a particle swarm algorithm to obtain a target instantaneous attitude parameter specifically includes:

setting the shortest moving distance, and randomly generating a first particle swarm in a feasible region of the first optimization model, wherein the feasible solution of the first particle swarm is a first individual position;

searching according to the first cost function to obtain the current optimal position of the particles and the optimal position of the particle swarm;

after adjusting the particle position in the first particle swarm, updating the current optimal particle position and the current optimal particle swarm position until the maximum iteration step number or the minimum change criterion is met;

and determining the target instantaneous attitude parameter according to the current optimal first individual position.

Further, in an embodiment of the present invention, the second optimization model includes a second objective function, and the second objective function is:

wherein the content of the first and second substances, n∈[1，2]，p∈[1，P]p denotes the number of ISAR radar systems, θ_rot、φ_rotAnd ω_rotRepresenting the spin parameters of the object to be solved,represents preset radar line-of-sight parameters,represents the central radar sight direction vector, D, of the ISAR radar system corresponding to the p-th ISAR observation image_n，pAnd the target Doppler dimension of the characteristic structure of the projection length of the nth target in the p ISAR observation image is shown.

Further, in an embodiment of the present invention, the step of solving the second optimization model by using a particle swarm optimization algorithm to obtain the target spin parameter specifically includes:

setting the shortest moving distance, and randomly generating a second particle swarm in the feasible region of the second optimization model, wherein the feasible solution of the second particle swarm is a second individual position;

searching according to the second cost function to obtain the current optimal position of the particles and the optimal position of the particle swarm;

after adjusting the position of the particles in the second particle swarm, updating the current optimal position of the particles and the optimal position of the particle swarm until the maximum iteration step number or the minimum change criterion is met;

and determining the target spin parameter according to the current optimal second body position.

Further, in one embodiment of the present invention, the attitude estimation of the spin space target is done according to the following formula:

wherein the content of the first and second substances,andrepresenting the characteristic attitude, alpha, of the object in spin space₁、α₂、β₁And beta₂Representing the instantaneous attitude parameters of the target,representing the rotation vector of the object in spin space, theta_rot、φ_rotAnd ω_rotRepresenting the target spin parameters.

In a second aspect, an embodiment of the present invention provides a spin space object attitude estimation system, including:

the first radar image sequence acquisition module is used for acquiring a plurality of first echo signals in a preset time period through a plurality of ISAR radar systems and performing range-Doppler processing on the first echo signals to obtain a first radar image sequence of a target area, wherein the first radar image sequence comprises a plurality of ISAR observation images;

a target distance dimension size and target doppler dimension size determination module, configured to extract two target projection length feature structures from each ISAR observation image, and determine a target distance dimension size of the target projection length feature structure in a distance dimension and a target doppler dimension size in a doppler dimension;

the central radar sight direction vector determining module is used for acquiring a first pitch angle and a first azimuth angle corresponding to each ISAR observation image and determining the central radar sight direction vector of each ISAR radar system according to the first pitch angle and the first azimuth angle;

the target instantaneous attitude parameter determining module is used for constructing a first optimization model according to the target distance dimension and the central radar sight direction vector, and solving the first optimization model by utilizing a particle swarm algorithm to obtain a target instantaneous attitude parameter;

and the target spin parameter determining module is used for constructing a second optimization model according to the target Doppler dimension size and the target instantaneous attitude parameter, solving the second optimization model by using a particle swarm algorithm to obtain a target spin parameter, and further finishing attitude estimation on the spin space target according to the target instantaneous attitude parameter and the target spin parameter.

In a third aspect, an embodiment of the present invention provides a spin space target attitude estimation apparatus, including:

at least one processor;

at least one memory for storing at least one program;

the at least one program, when executed by the at least one processor, causes the at least one processor to implement a method of estimating an attitude of a spin space object as described above.

In a fourth aspect, the present invention further provides a computer-readable storage medium, in which a processor-executable program is stored, and the processor-executable program is used to execute the above-mentioned method for estimating the attitude of a spin space object when executed by a processor.

Advantages and benefits of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention:

the method comprises the steps of synchronizing radar echo signals obtained by multi-station observation in a preset time period, then performing range-Doppler processing to obtain multi-frame synchronized ISAR observation images, then extracting projection size parameters of a target in the range direction and the Doppler direction from the obtained multi-frame ISAR observation images, establishing two independent optimization models by combining observation geometric parameters of all ISAR radar systems, and sequentially solving instantaneous attitude parameters and spinning parameters of a spinning space target by using a particle swarm optimization method to complete attitude estimation of the spinning space target. The method and the device can realize accurate inversion of the on-orbit instantaneous state of the spin space target, make up the defects of the existing single-station sequence imaging interpretation mode in solving high-order target dynamic parameter optimization by utilizing the observation angle resource corresponding to multi-station joint observation, avoid the fluctuation of target projection characteristics under certain observation angles, and improve the accuracy of the attitude estimation of the spin space target.

Drawings

In order to more clearly illustrate the technical solution in the embodiment of the present invention, the following description is made on the drawings required to be used in the embodiment of the present invention, and it should be understood that the drawings in the following description are only for convenience and clarity of describing some embodiments in the technical solution of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a flowchart illustrating steps of a method for estimating an attitude of a spin space target according to an embodiment of the present invention;

fig. 2 is an analysis diagram of a spatial target structure and a motion model used in a simulation experiment according to an embodiment of the present invention;

fig. 3 is a schematic diagram of a target projection length feature structure extracted by a simulation experiment provided in the embodiment of the present invention;

FIG. 4 is a block diagram of a system for estimating the attitude of a spin space object according to an embodiment of the present invention;

fig. 5 is a block diagram of a spin space target attitude estimation apparatus according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention. The step numbers in the following embodiments are provided only for convenience of illustration, the order between the steps is not limited at all, and the execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

In the description of the present invention, the meaning of a plurality is two or more, if there is a description to the first and the second for the purpose of distinguishing technical features, it is not understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the precedence of the indicated technical features. Furthermore, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

Referring to fig. 1, an embodiment of the present invention provides a method for estimating an attitude of a spin space target, specifically including the following steps:

s101, a plurality of first echo signals in a preset time period are obtained through a plurality of ISAR radar systems, and range-Doppler processing is carried out on the first echo signals to obtain a first radar image sequence of a target area, wherein the first radar image sequence comprises a plurality of ISAR observation images.

Specifically, in the embodiment of the present invention, a 3-station ISAR radar system receives a first echo signal within a preset time period, and then performs range-doppler processing after synchronizing the first echo signal received by the 3-station ISAR radar system, so as to obtain a first radar image sequence of a target area, where the sequence includes 3 ISAR observation images of the target area.

S102, extracting two target projection length feature structures from each ISAR observation image, and determining the target distance dimension size of the target projection length feature structures in the distance dimension and the target Doppler dimension size in the Doppler dimension.

Specifically, 2 target projection length feature structures are respectively extracted from the 3 frames of ISAR observation images, and the projection length of each feature structure in two dimensions of distance and Doppler is recorded, that is, the target distance dimension size and the target Doppler dimension size.

S103, acquiring a first pitch angle and a first azimuth angle corresponding to each ISAR observation image, and determining a central radar sight direction vector of each ISAR radar system according to the first pitch angle and the first azimuth angle.

Specifically, according to radar observation pitch angle and azimuth angle information corresponding to each frame of ISAR observation image, a central radar sight line direction vector of the corresponding ISAR radar system is calculated.

Further as an optional implementation, the calculation formula of the central radar sight direction vector is as follows:

wherein the content of the first and second substances,representing the central radar line-of-sight vector, θ (t)_m) Denotes a first pitch angle, phi (t)_m) Denotes a first azimuth angle, t_mCoherent integration of representation ISAR observation imagesThe center moment of time.

Specifically, the first pitch angle is an included angle between a radar sight line and an XOY plane of the body coordinate system, and the first azimuth angle is an included angle between a projection of the radar sight line on the XOY plane and a Y axis.

S104, constructing a first optimization model according to the target distance dimension and the central radar sight direction vector, and solving the first optimization model by utilizing a particle swarm algorithm to obtain the target instantaneous attitude parameter.

As a further optional implementation manner, the first optimization model includes a first objective function and a first constraint condition, and the first objective function is:

wherein the content of the first and second substances,n∈[1，2]，p∈[1，P]p denotes the number of ISAR radar systems, α_nAnd beta_nRepresenting instantaneous attitude parameters, R, of the object to be solved_n，pRepresenting the target distance dimension L of the n-th target projection length feature structure in the p-th ISAR observation image_nRepresenting the true size of the nth target projection length feature,representing a central radar sight direction vector of the ISAR radar system corresponding to the p-th ISAR observation image;

the first constraint is:

tanα₁tanα₂+cos(β₁-β₂)＝0

wherein alpha is₁、α₂、β₁And beta₂Representing the instantaneous attitude parameters of the target to be solved.

Specifically, in the embodiment of the invention, P is 3, α_nRepresents the included angle beta between the nth target projection length characteristic and the XOY plane of the target specimen coordinate system_nIndicating the nth object throwThe shadow length features are characterized by the angle between the projection of the XOY plane and the Y axis. It will be appreciated that α is solved for by the first optimization model₁、α₁、β₁And beta₂Then, the instantaneous attitude of the spinning space object can be determined.

Further as an optional implementation manner, the step of solving the first optimization model by using a particle swarm algorithm to obtain a target instantaneous attitude parameter specifically includes:

setting the shortest moving distance, and randomly generating a first particle swarm in a feasible region of the first optimization model, wherein the feasible solution of the first particle swarm is a first individual position;

searching according to the first cost function to obtain the current optimal position of the particles and the optimal position of the particle swarm;

after adjusting the position of the particles in the first particle swarm, updating the current optimal position of the particles and the optimal position of the particle swarm until the maximum iteration step number or the minimum change criterion is met;

and determining the target instantaneous attitude parameter according to the current optimal first individual position.

Specifically, the steps of solving the first optimization model by using the particle swarm optimization to obtain the target instantaneous attitude parameter are as follows:

s1041, setting the shortest moving distance, and randomly generating a first particle swarm in a feasible domain of the first optimization model, wherein a feasible solution is defined as a first individual position X_i＝(α₁，β₁，α₂，β₂)^T；

S1042, searching the current particle optimal position Pbest and the particle swarm optimal position Gbest according to the following first cost function:

wherein, the confidence factor A₁Determining the constraint strength of the prior condition in the optimization solution, in the embodiment of the invention A₁Set to 0.93:

s1043, adjusting the position of the particles in the first particle swarm according to the following update formula:

V_i(t+1)＝A₂V_i(t)+A₃rand₁(Pbest-X_i(t))+A₄rand₂(Gbest-X_i(t))

X_i(t+1)＝X_i(t)+V_i(t)

wherein, V_i(t) and X_i(t) is the motion and position of the tth individual in the ith iteration, A₂Is an inertia factor, A₃And A₄Is a weight factor for balancing individual experience and group experience, and a random parameter rand₁And rand₂Obey [0, 1]Are uniformly distributed.

And S1044, recalculating the individual objective function value according to the first cost function, and updating the current optimal particle position and the optimal particle swarm position. If the maximum iteration step number or the minimum change criterion is met, stopping the iteration and skipping step S1045; otherwise, jumping to step S1043; the minimum change criterion refers to that the change of the optimal positions of the particles and the optimal positions of the particle swarm needs to be larger than a minimum moving threshold value in the updating process.

S1045, stopping iteration and outputting the current optimal first individual position

S105, constructing a second optimization model according to the Doppler dimension of the target and the instantaneous attitude parameter of the target, solving the second optimization model by using a particle swarm algorithm to obtain a target spinning parameter, and further finishing attitude estimation of the spinning space target according to the instantaneous attitude parameter of the target and the target spinning parameter.

As a further optional implementation manner, the second optimization model includes a second objective function, and the second objective function is:

wherein the content of the first and second substances, n∈[1，2]，p∈[1，P]p denotes the number of ISAR radar systems, θ_rot、φ_rotAnd ω_rotRepresenting the spin parameters of the object to be solved,represents preset radar line-of-sight parameters,represents the central radar sight direction vector, D, of the ISAR radar system corresponding to the p-th ISAR observation image_n，pAnd the target Doppler dimension of the characteristic structure of the projection length of the nth target in the p ISAR observation image is shown.

Specifically, in the invention embodiment, P is 3, θ_rotRepresents the included angle phi between the rotating shaft of the spinning space target and the XOY plane of the target specimen coordinate system_rotRepresenting the angle, ω, between the projection of the axis of rotation of the object in spin space in the XOY plane and the Y axis_rotRepresenting the average rotational speed of the spin space object. It will be appreciated that θ is solved by the second optimization model_rot、φ_rotAnd ω_rotThen, the spin attitude of the spin space object can be determined.

Further as an optional implementation manner, the step of solving the second optimization model by using a particle swarm algorithm to obtain the target spin parameter specifically includes:

setting the shortest moving distance, and randomly generating a second particle swarm in the feasible region of the second optimization model, wherein the feasible solution of the second particle swarm is a second entity position;

searching according to the second cost function to obtain the current optimal position of the particles and the optimal position of the particle swarm;

after adjusting the position of the particles in the second particle swarm, updating the current optimal position of the particles and the optimal position of the particle swarm until the maximum iteration step number or the minimum change criterion is met;

and determining the target spin parameter according to the current optimal second body position.

Specifically, the steps of solving the second optimization model by using the particle swarm optimization to obtain the target spin parameter are as follows:

s1051, setting the shortest moving distance, randomly generating a second particle swarm in the feasible domain of the second optimization model, and defining the feasible solution as a second entity position X_i＝(θ_rot，φ_rot，ω_rot)^T；

S1052, searching the current particle optimal position Pbest and the particle swarm optimal position Gbest according to the following second cost function:

s1053, adjusting the position of the particles in the second particle swarm according to the following updating formula:

V_i(t+1)＝A₅V_i(t)+A₆rand₁(Pbest-X_i(t))+A₇rand₂(GbeSt-X_i(t))

X_i(t+1)＝X_i(t)+V_i(t)

wherein, V_i(t) and X_i(t) is the motion and position of the tth individual in the ith iteration, A₅Is an inertia factor, A₆And A₇Is a weight factor for balancing individual experience and group experience, and a random parameter rand₁And rand₂Obey [0, 1]Are uniformly distributed.

S1054, recalculating the individual objective function value according to the second cost function, updating the current particle optimal position and the particle swarm optimal position, and stopping iteration and skipping step S1055 if the maximum iteration step number or the minimum change criterion is met; otherwise, jumping to step S1054; the minimum change criterion refers to that the change of the optimal positions of the particles and the optimal positions of the particle swarm needs to be larger than a minimum moving threshold value in the updating process.

S1055, stopping iteration and outputting the current optimal second body position X_i＝(θ_rot，φ_rot，ω_rot)^T。

Further as an alternative embodiment, the attitude estimation of the spin space object is done according to the following formula:

wherein the content of the first and second substances,andrepresenting the characteristic attitude, alpha, of the object in spin space₁、α₂、β₁And beta₂Representing the instantaneous attitude parameters of the target,representing the rotation vector of the object in spin space, theta_rot、φ_rotAnd ω_rotRepresenting the target spin parameters.

The method comprises the steps of synchronizing radar echo signals obtained by multi-station observation in a preset time period, then performing range-Doppler processing to obtain multi-frame synchronized ISAR observation images, then extracting projection size parameters of a target in the range direction and the Doppler direction from the obtained multi-frame ISAR observation images, establishing two independent optimization models by combining observation geometric parameters of all ISAR radar systems, and sequentially solving instantaneous attitude parameters and spinning parameters of a spinning space target by using a particle swarm optimization method to complete attitude estimation of the spinning space target. Compared with the prior art, the embodiment of the invention has the following advantages:

1) the embodiment of the invention utilizes the relative projection change relationship of the multi-station ISAR synchronous images of the spinning space target, combines the space projection theory, and realizes accurate inversion on the on-orbit instantaneous state of the space target through the two-dimensional ISAR image sequence.

2) According to the embodiment of the invention, the observation angle resource corresponding to station joint observation is utilized to make up the defects of the existing single-station sequence imaging interpretation mode in the aspect of solving high-order target dynamic parameter optimization, the fluctuation of target projection characteristics under certain observation angles is avoided, and the robustness of the method in actual cooperative and non-cooperative space target state estimation application is improved.

In order to further verify the accuracy of the embodiment of the present invention, the effect of the embodiment of the present invention is further described below with reference to simulation experiments.

The structure of the space target adopted in the simulation experiment of the embodiment of the invention is shown in figure 2, wherein theta represents the radar observation pitch angle, namely the included angle between the radar sight line and the XOY plane of the body coordinate system, phi represents the radar observation azimuth angle, namely the included angle between the projection of the radar sight line on the XOY plane and the Y axis, and LOS_centerIndicating the direction of the line of sight of the central radar,the solar wing boundary of the target has an obvious linear structure by representing the central radar sight direction vector. The main parameters of the simulation experiment of the embodiment of the present invention are shown in table 1 below.

TABLE 1

Simulation experiment 1: the method of the invention is adopted to extract the target projection length characteristic structure of 3 synchronous ISAR observation images of the space target in figure 2, figure 3(a), figure 3(b) and figure 3(c) show the target projection length characteristic structure extracted from the 3 ISAR observation images, and feature 1 and feature 2 are respectively used to represent two target projection length characteristic structures. Then, two optimization models are constructed according to the obtained 3-station image target distance dimension, the target Doppler dimension and the three-station central radar sight direction vectors, each state parameter of the target is solved by using a particle swarm algorithm, and the result is shown in the following table 2.

	True value	Estimated value	Error of the measurement
				Characteristic 1 attitude	(0.2387，-0.2002，-0.9502)	(-0.2620，0.2198，0.9397)	1.87 degree
Characteristic 2 attitude	(0.6505，0.7595，0.0034)	(0.6428，0.7660，-0.0000)	0.61 degree
				Self-spin axis pointing	(1.0000，0.0000，0.0000)	(0.9995，0.0298，0.0094)	1.81 degree
Rotational speed	0.0150rad/s	0.0151rad/s	0.0001rad/s

TABLE 2

As can be seen from fig. 3(a), 3(b), and 3(c), stable extraction of the feature structure of the spatial object can be substantially ensured. As can be seen from table 2, the orientation of the estimated feature is substantially consistent with the orientation of the real feature, the average error is within 3 degrees, the estimated target spin direction is substantially consistent with the real target spin direction, and the estimated target spin speed is closer to the real target spin speed in value, so that the on-orbit state of the spatial target can be determined.

Simulation experiment 2: the method is adopted to test in a target precession state, namely, the target rotates around a fixed shaft at a constant speed in a body coordinate system. The target rotation speed was set to 0.015rad/s and the rotation speed of the rotary shaft was set to 0 rad/s. The target 6 instantaneous state parameters were estimated from 60 seconds of continuous observation, and the target state estimation results are shown in table 3 below.

TABLE 3

As can be seen from table 3, in the in-orbit state of the target, the orientation of the estimated feature is substantially consistent with the orientation of the real feature, the average error is within 3 degrees, the estimated target spin direction is substantially consistent with the real target spin direction, and the estimated target spin speed is closer to the real target spin speed in value, so that the in-orbit state of the spatial target can be determined.

Simulation experiment 3: the method is adopted to test the target in a nutation state, namely, the target rotates around a certain fixed shaft at a constant speed besides the basic precession. The target rotation speed was set to 0.015rad/s and the spindle rotation speed was set to 0.005 rad/s. The target 6 instantaneous state parameters were estimated from 60 seconds of continuous observation, and the target state estimation results are shown in table 4 below.

TABLE 4

As can be seen from table 4, in the in-orbit nutation state of the target, the orientation of the estimated feature is substantially consistent with the orientation of the real feature, the average error is within 3 degrees, the estimated target spin direction is substantially consistent with the real target spin direction, and the estimated target spin speed is closer to the real target spin speed in value, so that the in-orbit state of the spatial target can be determined.

Simulation experiment 4: the method is adopted to test the target in a rolling state, namely the target rotation shaft and the rotation speed are continuously changed. The target 6 instantaneous state parameters were estimated from 60 seconds of continuous observation, and the target state estimation results are shown in table 5 below.

TABLE 5

As can be seen from table 5, in the target rolling state, the orientation of the estimated feature is substantially consistent with the orientation of the real feature, the average error is within 3 degrees, the estimated target spin direction is substantially consistent with the real target spin direction, and the estimated target spin speed is closer to the real target spin speed in value, so that the in-orbit state of the spatial target can be determined.

Referring to fig. 4, an embodiment of the present invention provides a spin space target attitude estimation system, including:

the first radar image sequence acquisition module is used for acquiring a plurality of first echo signals in a preset time period through a plurality of ISAR radar systems and performing range-Doppler processing on the first echo signals to obtain a first radar image sequence of a target area, wherein the first radar image sequence comprises a plurality of ISAR observation images;

the target distance dimension size and target Doppler dimension size determining module is used for extracting two target projection length feature structures from each ISAR observation image and determining the target distance dimension size of the target projection length feature structures in the distance dimension and the target Doppler dimension size in the Doppler dimension;

the central radar sight direction vector determining module is used for acquiring a first pitch angle and a first azimuth angle corresponding to each ISAR observation image and determining the central radar sight direction vector of each ISAR radar system according to the first pitch angle and the first azimuth angle;

the target instantaneous attitude parameter determining module is used for constructing a first optimization model according to the target distance dimension and the central radar sight direction vector, and solving the first optimization model by utilizing a particle swarm algorithm to obtain target instantaneous attitude parameters;

and the target spin parameter determining module is used for constructing a second optimization model according to the target Doppler dimension size and the target instantaneous attitude parameter, solving the second optimization model by using a particle swarm algorithm to obtain a target spin parameter, and further finishing attitude estimation on the spin space target according to the target instantaneous attitude parameter and the target spin parameter.

The contents in the above method embodiments are all applicable to the present system embodiment, the functions specifically implemented by the present system embodiment are the same as those in the above method embodiment, and the beneficial effects achieved by the present system embodiment are also the same as those achieved by the above method embodiment.

Referring to fig. 5, an embodiment of the present invention provides a spin space target attitude estimation apparatus, including:

at least one processor;

at least one memory for storing at least one program;

when the at least one program is executed by the at least one processor, the at least one processor may implement the method for estimating the attitude of the object in spin space.

The contents in the above method embodiments are all applicable to the present apparatus embodiment, the functions specifically implemented by the present apparatus embodiment are the same as those in the above method embodiments, and the advantageous effects achieved by the present apparatus embodiment are also the same as those achieved by the above method embodiments.

Embodiments of the present invention also provide a computer-readable storage medium, in which a program executable by a processor is stored, and the program executable by the processor is used for executing the above-mentioned method for estimating the attitude of a spin space target.

The computer-readable storage medium of the embodiment of the invention can execute the method for estimating the attitude of the spin space target provided by the embodiment of the method of the invention, can execute any combination of the implementation steps of the embodiment of the method, and has corresponding functions and beneficial effects of the method.

The embodiment of the invention also discloses a computer program product or a computer program, which comprises computer instructions, and the computer instructions are stored in a computer readable storage medium. The computer instructions may be read by a processor of a computer device from a computer-readable storage medium, and executed by the processor to cause the computer device to perform the method illustrated in fig. 1.

In alternative embodiments, the functions/acts noted in the block diagrams may occur out of the order noted in the operational illustrations. 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/acts involved. Furthermore, the embodiments presented and described in the flow charts of the present invention are provided by way of example in order to provide a more thorough understanding of the technology. The disclosed methods are not limited to the operations and logic flows presented herein. Alternative embodiments are contemplated in which the order of various operations is changed and in which sub-operations described as part of larger operations are performed independently.

Furthermore, although the present invention is described in the context of functional modules, it should be understood that, unless otherwise stated to the contrary, one or more of the above-described functions and/or features may be integrated in a single physical device and/or software module, or one or more of the functions and/or features may be implemented in a separate physical device or software module. It will also be appreciated that a detailed discussion of the actual implementation of each module is not necessary for an understanding of the present invention. Rather, the actual implementation of the various functional modules in the apparatus disclosed herein will be understood within the ordinary skill of an engineer, given the nature, function, and internal relationship of the modules. Accordingly, those skilled in the art can, using ordinary skill, practice the invention as set forth in the claims without undue experimentation. It is also to be understood that the specific concepts disclosed are merely illustrative of and not intended to limit the scope of the invention, which is defined by the appended claims and their full scope of equivalents.

The above functions, if implemented in the form of software functional units and sold or used as a separate product, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the above method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

The logic and/or steps represented in the flowcharts or otherwise described herein, e.g., an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.

More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Further, the computer readable medium could even be paper or another suitable medium upon which the above described program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.

It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.

In the foregoing description of the specification, reference to the description of "one embodiment/example," "another embodiment/example," or "certain embodiments/examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.