CN114254485B

CN114254485B - Radar signal simulation method for microscale state of artificial satellite

Info

Publication number: CN114254485B
Application number: CN202111426242.3A
Authority: CN
Inventors: 李刚; 焦健; 王建文; 赵志纯
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2021-11-25
Filing date: 2021-11-25
Publication date: 2024-04-19
Anticipated expiration: 2041-11-25
Also published as: CN114254485A

Abstract

The application provides a radar signal simulation method aiming at a micro-motion state of an artificial satellite, which comprises the following steps: based on a preset number of scattering points, establishing a satellite scattering point three-dimensional simulation model; determining a plurality of satellite micro motions to be simulated, respectively establishing a motion model for each satellite micro motion, calculating the distance from each scattering point to a radar under each motion model, and calculating radar echo data of the current satellite micro motion according to the distance from each scattering point to the radar, wherein the plurality of satellite micro motions comprise: the satellite integrally rotates and compound the vibration, the solar panel rotates along the long axis, the solar panel expands and the antenna expands and compound the rotation; and carrying out time-frequency analysis on the radar echo data of each satellite micro-motion to obtain a time-frequency spectrogram of each satellite micro-motion. The method can simulate the micro Doppler effect caused by the micro motion of the satellite, and display time-frequency spectrograms under different micro motion states, thereby being beneficial to more efficiently monitoring the micro motion of the satellite.

Description

Radar signal simulation method for microscale state of artificial satellite

Technical Field

The application relates to the technical field of space target simulation modeling, in particular to a radar signal simulation method aiming at a micro-motion state of an artificial satellite.

Background

With the development of the technology of aerospace equipment, a new generation of satellites can not only rotate an antenna, expand and retract a solar sailboard and the like, but also can carry out complex operations such as rapid maneuvering, orbit transfer, mechanical arm grabbing and the like. However, due to the increasing number of satellites in orbit, the risk of space debris collision increases sharply, and maneuver avoidance is required to be performed to avoid the collision, but more resources are required to be consumed for each avoidance operation. The space situation sensing system of the satellite is faced with increasingly complex and changeable space safety environments, especially with low-orbit large-scale constellation explosion and enhanced space system function ambiguity, and has unprecedented challenges.

In the related art, the monitoring means aiming at space targets such as artificial satellites cannot achieve seamless coverage of a space domain and a time domain, the detection distance and the detection precision are low, and abundant actual data cannot be acquired for researching and judging the space targets such as the artificial satellites, so that the research of artificial satellite motion state simulation technology is necessary to develop, and technical support is provided for monitoring and sensing of the artificial satellites. The radar has all-weather detection capability in all days as one of important means essential for monitoring and sensing of artificial satellite, and radar characteristic signal is the basis for radar target identification.

In addition, small movements of the spatial target or components of the target other than the translational motion of the body, such as rotation, vibration, precession, etc., are referred to as micro-movements, and the basic micro-movement types involved in typical micro-movement behavior of satellites include rotation, vibration, precession, etc. The micro-motion of the target reflects the fine characteristics of the target, has important value and is widely focused in the field of radar detection and identification.

However, due to the lack of radars dedicated to spatial target jog monitoring perception, the amount of accumulated radar echo data is insufficient, limiting the intensive research in this area to some extent. Therefore, a method for simulating the radar signal of the satellite micro-motion state is needed to provide support for designing a more efficient satellite monitoring system.

Disclosure of Invention

The present application aims to solve at least one of the technical problems in the related art to some extent.

Therefore, a first object of the present application is to provide a radar signal simulation method for micro motion state of an artificial satellite, which can simulate micro doppler effect caused by micro motion of the satellite and display time-frequency spectrograms under different micro motion states, so as to solve the problems of lack of radar specially used for micro motion monitoring and sensing of a space target, insufficient accumulated radar echo data, and limitation of deep research on micro motion of the space target.

A second object of the present application is to provide a radar signal simulation device for a micro-motion state of a satellite.

A third object of the present application is to propose a non-transitory computer readable storage medium.

To achieve the above objective, an embodiment of a first aspect of the present application provides a radar signal simulation method for a micro motion state of an artificial satellite, including the following steps:

Based on a preset number of scattering points, a satellite scattering point three-dimensional simulation model is established, and each preset part in the satellite scattering point three-dimensional simulation model is provided with a corresponding scattering point group;

Determining a plurality of satellite micro motions to be simulated, establishing a radar coordinate system, a target body coordinate system and a reference coordinate system, respectively establishing a motion model for each satellite micro motion, calculating the distance from each scattering point to a radar under each motion model, and calculating radar echo data of the current satellite micro motion according to the distance from each scattering point to the radar, wherein the plurality of satellite micro motions comprise: the satellite integrally rotates and compound the vibration, the solar panel rotates along the long axis, the solar panel expands and the antenna expands and compound the rotation;

And carrying out time-frequency analysis on the radar echo data of each satellite micro-motion to obtain a time-frequency spectrogram of each satellite micro-motion.

Optionally, in one embodiment of the present application, calculating radar echo data under a motion model of the satellite global rotation compound vibration includes: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system, and an instantaneous rotational angular speed, a vibration frequency, a vibration amplitude and a vibration direction of the satellite under a target body coordinate system; acquiring a rotation matrix according to the rotation angular speed, and calculating a first position coordinate of any scattering point at the current moment according to the rotation matrix; calculating a vibration distance at the current moment according to the vibration frequency, the vibration amplitude and the vibration direction, and updating the first position coordinate into a second position coordinate according to the vibration distance; converting the second position coordinate into the reference coordinate system according to the initial attitude angle, and acquiring a third position coordinate of any scattering point; converting the third position coordinate into the radar coordinate system according to the initial distance and the translation speed, acquiring a fourth position coordinate of any scattering point, and calculating the distance between any scattering point and the radar according to the fourth position coordinate; and calculating radar echo data of the integral rotation composite vibration of the satellite according to the distance from each scattering point to the radar.

Optionally, in one embodiment of the present application, calculating radar echo data under a motion model in which the solar array rotates along a long axis includes: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system; dividing all scattering points into a solar panel scattering point and a satellite component scattering point except for the solar panel; calculating first partial radar echo data of the solar sailboard rotating along the long axis based on the solar sailboard scattering points; calculating second partial radar echo data of the solar panel rotating along the long axis based on the satellite component scattering points except the solar panel; and adding the first part of radar echo data of the solar array rotating along the long axis and the second part of radar echo data of the solar array rotating along the long axis to obtain radar echo data of the solar array rotating along the long axis.

Optionally, in one embodiment of the present application, calculating radar echo data under the motion model of the solar array deployment includes: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system; dividing all scattering points into a solar panel scattering point and a satellite component scattering point except for the solar panel; calculating a fifth position coordinate of a scattering point of the solar panel at the current moment according to the length of the sub-panel and the unfolding angle of the solar panel at the current moment; calculating first partial radar echo data of solar panel expansion based on fifth position coordinates of the solar panel scattering points; calculating second partial radar echo data of solar array expansion based on sixth position coordinates of satellite component scattering points except the solar array; and adding the first part of radar echo data of the solar array expansion and the second part of radar echo data of the solar array expansion to obtain radar echo data of the solar array expansion.

Optionally, in one embodiment of the present application, calculating radar echo data under a motion model of the antenna deployment compound rotation includes: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system, and a satellite antenna unfolding angular speed, a bottom connection point coordinate and an antenna rotation angular speed of the satellite under a target body coordinate system; dividing all scattering points into antenna scattering points and satellite component scattering points except for the antenna; calculating a seventh position coordinate of an antenna scattering point at the current moment according to the angular velocity of satellite antenna expansion, the bottom connection point coordinate and the angular velocity of antenna rotation; calculating first partial radar echo data of the antenna unfolding composite rotation based on seventh position coordinates of the antenna scattering points; calculating second partial radar echo data of the antenna unfolding composite rotation based on eighth position coordinates of satellite component scattering points except the antenna; and adding the first part of radar echo data of the antenna unfolding composite rotation and the second part of radar echo data of the antenna unfolding composite rotation to obtain the radar echo data of the solar array unfolding.

Optionally, in one embodiment of the present application, the radar echo data of each of the satellite micro-motions is time-frequency analyzed by the following formula:

T_s(t,ω)＝∫s(τ)w(τ-t)e^-jωτdτ

where w (t) is a window function and s (t) is radar echo data.

Alternatively, in one embodiment of the application, radar echo data is calculated by the following formula:

Where σ _l (t) is the echo amplitude modulation coefficient of the scattering point, c is the propagation velocity of electromagnetic wave, and r _l (t) is the distance from the scattering point to the radar.

To achieve the above object, a second aspect of the present application provides a radar signal simulation device for a micro motion state of an artificial satellite, including:

The system comprises a building module, a satellite scattering point three-dimensional simulation model, a data acquisition module and a data acquisition module, wherein the building module is used for building the satellite scattering point three-dimensional simulation model based on a preset number of scattering points, and each preset part in the satellite scattering point three-dimensional simulation model is provided with a corresponding scattering point group;

The computing module is used for determining a plurality of satellite micro motions to be simulated, establishing a radar coordinate system, a target body coordinate system and a reference coordinate system, respectively establishing a motion model for each satellite micro motion, computing the distance from each scattering point to a radar under each motion model, and computing radar echo data of the current satellite micro motion according to the distance from each scattering point to the radar, wherein the plurality of satellite micro motions comprise: the satellite integrally rotates and compound the vibration, the solar panel rotates along the long axis, the solar panel expands and the antenna expands and compound the rotation;

and the analysis module is used for carrying out time-frequency analysis on the radar echo data of each satellite micro-motion and obtaining a time-frequency spectrogram of each satellite micro-motion.

Optionally, in one embodiment of the present application, the computing module is specifically configured to: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system, and an instantaneous rotational angular speed, a vibration frequency, a vibration amplitude and a vibration direction of the satellite under a target body coordinate system; acquiring a rotation matrix according to the rotation angular speed, and calculating a first position coordinate of any scattering point at the current moment according to the rotation matrix; calculating a vibration distance at the current moment according to the vibration frequency, the vibration amplitude and the vibration direction, and updating the first position coordinate into a second position coordinate according to the vibration distance; converting the second position coordinate into the reference coordinate system according to the initial attitude angle, and acquiring a third position coordinate of any scattering point; converting the third position coordinate into the radar coordinate system according to the initial distance and the translation speed, acquiring a fourth position coordinate of any scattering point, and calculating the distance between any scattering point and the radar according to the fourth position coordinate; and calculating radar echo data of the integral rotation composite vibration of the satellite according to the distance from each scattering point to the radar.

The technical scheme provided by the embodiment of the application at least has the following beneficial effects: the application can simulate the micro Doppler effect caused by the micro motion of the satellite, displays the time-frequency spectrograms under different micro motion states, solves the technical problems that the lack of radar special for micro motion monitoring sensing of a space target in the related technology and the accumulated radar echo data volume is insufficient, which limits the deep research on the micro motion of the space target, researches the micro motion state of the satellite through the simulation technology, can acquire the fine characteristics of the satellite with lower cost research, provides theoretical support for designing a more efficient satellite monitoring system, and is beneficial to more accurately and efficiently monitoring the micro motion of the satellite.

In order to achieve the above embodiments, the third aspect of the present application further proposes a non-transitory computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the radar signal simulation method for the micro-motion state of the satellite in the above embodiments.

Additional aspects and advantages of the 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.

Drawings

The foregoing and/or additional aspects and advantages of the application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

fig. 1 is a flowchart of a radar signal simulation method for a micro-motion state of an artificial satellite according to an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a satellite model constructed by simulation according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a three-dimensional simulation model of a satellite scattering point according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a geometric model of satellite observation according to an embodiment of the present application;

FIG. 5 is a schematic diagram of a geometric model of a satellite overall rotation compound vibration according to an embodiment of the present application;

FIG. 6 is a schematic view of a geometric model of a satellite solar panel according to an embodiment of the present application rotated along a long axis;

FIG. 7 is a schematic view of a geometric model of a satellite solar panel deployment according to an embodiment of the present application;

FIG. 8 is a schematic diagram of a kinematic model of satellite solar array deployment according to an embodiment of the present application;

fig. 9 is a schematic diagram of a geometric model of satellite antenna unfolding composite rotation according to an embodiment of the present application;

FIG. 10 is a time-frequency spectrum diagram of a satellite overall rotation compound vibration according to an embodiment of the present application;

FIG. 11 is a time-frequency spectrum diagram of a satellite solar panel according to an embodiment of the present application rotated along a long axis;

FIG. 12 is a time-frequency spectrum of a satellite solar panel according to an embodiment of the present application;

fig. 13 is a time-frequency spectrum diagram of a satellite antenna unfolding composite rotation according to an embodiment of the present application;

fig. 14 is a schematic structural diagram of a radar signal simulation device for a micro-motion state of an artificial satellite according to an embodiment of the present application.

Detailed Description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.

It should be noted that typical micro-motion behaviors of the satellite include main load actions such as antenna unfolding and folding, antenna or lens rotation, solar sailboard rotation, and fault state rolling, and the related basic micro-motion types include rotation, vibration, precession, and the like, and micro-motion of the satellite reflects fine features of the satellite and has important value. Aiming at the technical problems that the lack of radar specially used for micro-motion monitoring and sensing of a space target in the prior art and the insufficient quantity of accumulated radar echo data lead to limitation of deep research on micro-motion of the space target, the application provides a radar signal simulation method and a radar signal simulation device aiming at an artificial satellite micro-motion state.

The following describes a radar signal simulation method and device for a micro-motion state of an artificial satellite according to the embodiment of the invention with reference to the accompanying drawings.

Fig. 1 is a flowchart of a radar signal simulation method for a micro-motion state of an artificial satellite according to an embodiment of the present application, as shown in fig. 1, the method includes the following steps:

step 101, a satellite scattering point three-dimensional simulation model is established based on a preset number of scattering points, and each preset component in the satellite scattering point three-dimensional simulation model is provided with a corresponding scattering point group.

The preset number of scattering points can be determined to be different values according to actual requirements, for example, the number of scattering points can be determined according to actual factors such as the shape and the size of a satellite, the simulation precision requirement and the like.

In one embodiment of the application, a satellite model is built in simulation software, and then scattering points of a satellite are simulated according to the set of built satellite prototypes, so that a three-dimensional simulation model of the satellite scattering points is built according to a determined number of scattering points.

For example, as shown in fig. 2, the satellite prototype constructed by the simulation of the present application includes a satellite body, a measurement and control antenna, a data transmission antenna, a solar panel, and other components, where the satellite model shown in fig. 2 is in a state where the solar panel and the antenna are unfolded. Then, a three-dimensional scattering point model is established in simulation software according to the shape and the size of the satellite, N scattering points are provided for the simulation satellite, N scattering points are correspondingly provided according to the satellite prototype, the three-dimensional satellite scattering point simulation model shown in fig. 3 is formed by the scattering points, and an initial position matrix obtained by the initial positions of the scattering points is as follows:

It should be noted that, each preset component in the three-dimensional simulation model of the satellite scattering points constructed by the application has a corresponding scattering point group, wherein the preset component can be a key component in the satellite, namely a main component for micro-motion of the satellite. In addition, in one embodiment of the present application, the radar reflection intensity σ of the scattering point may be determined according to the shape and the material of each component of the satellite.

Step 102, determining a plurality of satellite micro-motions to be simulated, establishing a radar coordinate system, a target body coordinate system and a reference coordinate system, respectively establishing a motion model for each satellite micro-motion, calculating the distance from each scattering point to a radar under each motion model, and calculating radar echo data of the current satellite micro-motion according to the distance from each scattering point to the radar, wherein the plurality of satellite micro-motions comprise: the satellite integrally rotates and compound vibrates, the solar panel rotates along the long axis, and the solar panel expands and the antenna expands and compound rotates.

The plurality of satellite micro-motions to be simulated may be typical micro-motions of each satellite, and for convenience of clarity of describing the simulation method of the present application, in the embodiment of the present application, the plurality of satellite micro-motions include: the four micro motions of satellite integral rotation and compound vibration, solar panel rotation along a long axis, solar panel unfolding and antenna unfolding and compound rotation are illustrated. Of course, the radar signal simulation method for the micro-motion state of the artificial satellite can expand the simulation of other micro-motions.

It should be noted that, based on the established scattering point model, radar echo can be regarded as being formed by overlapping echoes of scattering points forming a target moving part, so the application establishes a moving model for each satellite micro-motion respectively, calculates the distance from each scattering point to the radar under each moving model, calculates echo data of the scattering points according to the distance from each scattering point to the radar, and can acquire radar echo data of the current satellite micro-motion after overlapping the echo data of each scattering point, thereby facilitating the subsequent study on the micro-motion state according to the radar echo data under each moving state.

It should be noted that, in order to facilitate calculation of echo data under a plurality of different motion models, the present application first establishes a radar coordinate system, a target body coordinate system, and a reference coordinate system suitable for each motion model. In specific implementation, as a possible implementation manner, as shown in fig. 4, the present application firstly establishes a spatial target rotation observation geometric model, and presumes that a target (for example, a satellite) translates and rotates relative to a stationary radar, wherein the observation radar is located at an origin Q of a radar coordinate system (U, V, W), and establishes a body coordinate system (x, y, z) with a target centroid O as an origin, and the coordinate system changes along with movement of the target. In order to facilitate the analysis of the movement of the target, the application introduces a reference coordinate system (X, Y, Z), the origin of which coincides with the origin of the target body coordinate system and is parallel to the radar coordinate system, the reference coordinate system (X, Y, Z) and the target body coordinate system (X, Y, Z) having the same translational component but not including rotational components with respect to the fixed radar coordinate system (U, V, W).

In the embodiment of the present application, if the satellite has N scattering points, the distance between any first scattering point and the radar can be expressed by the following formula:

wherein, For the distance change caused by satellite translation,/>Distance variations for satellite micro-motions.

Further, after determining the scattering point distance from the radar, in one embodiment of the application, radar echo data may be calculated by the following formula:

Where σ _l (t) is the echo amplitude modulation coefficient of the scattering point, c is the propagation velocity of electromagnetic wave, and r _l (t) is the distance from the scattering point to the radar. Further, the phase function and doppler shift function of the echo signal can be expressed as:

Wherein the first term f _Bluk is Doppler shift induced by translation and the second term f _m is micro Doppler shift induced by rotation.

In order to more clearly illustrate the specific implementation manner of the method for acquiring radar echo data of satellite micro-motions, the following detailed description is directed to four exemplary satellite micro-motions respectively.

As a first example, the satellite overall rotation compound vibration is described.

Wherein normally in-orbit satellites are required to maintain a stable three-axis attitude to ensure that the transmitting and receiving antennas remain orientated to ground and the solar panels remain orientated to the sun. Abnormal or failed satellites often lose their own attitude control ability, resulting in overall rotation and small vibrations.

In this example, the motion model of the overall rotational superimposed vibration of the satellite established by the present application is shown in FIG. 5, where the centroid O of the satellite moves to point O "and the target scattering point P 'moves to point P'" over time t. For ease of analysis, the motion process of point P is decomposed into translation at speed to point P' and then angular velocityFrom point P 'to point P ", and finally from point P" to point P' ".

In one embodiment of the application, calculating radar echo data under a motion model of the global rotational composite vibration of the satellite comprises the steps of: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system, and an instantaneous rotational angular speed, a vibration frequency, a vibration amplitude and a vibration direction of the satellite under a target body coordinate system; acquiring a rotation matrix according to the rotation angular speed, and calculating a first position coordinate of any scattering point at the current moment according to the rotation matrix; calculating the vibration distance at the current moment according to the vibration frequency, the vibration amplitude and the vibration direction, and updating the first position coordinate into the second position coordinate according to the vibration distance; converting the second position coordinate into the reference coordinate system according to the initial attitude angle, and acquiring a third position coordinate of any scattering point; according to the initial distance and the translation speed, converting the third position coordinate into a radar coordinate system, obtaining a fourth position coordinate of any scattering point, and calculating the distance from any scattering point to the radar according to the fourth position coordinate; and calculating radar echo data of the integral rotation composite vibration of the satellite according to the distance from each scattering point to the radar.

Specifically, in the first step, radar basic parameters are set: center frequency f ₀, observation period T, sampling frequency f _s.

Second, setting the initial attitude angle of the satellite in the radar coordinate system as(Phi is roll angle, theta is pitch angle, phi is yaw angle), initial distance/>Translational velocity/>Instantaneous rotational angular velocity/>, under satellite body coordinate systemVibration frequency f, vibration amplitude A and vibration direction/>

Third, the rotation angle of the scattering point is calculated after the time tThe resulting rotation matrix is shown below:

fourth, calculating the coordinates of the scattering point position at the moment t after the movement is performed

Fifthly, calculating the vibration distance at the time t

Sixth, updating the position coordinates of the scattering point at the current observation timeWherein the arithmetic rules are as follows:

Seventh, according to the initial attitude angle of the satellite Converting satellite position coordinates into a reference coordinate system (X, Y, Z), new position coordinates/>Wherein the method comprises the steps of

Eighth step, according to the current scattering point position L', satellite initial distanceAnd satellite translational velocity/>Converting satellite position coordinates into a radar coordinate system (U, V, W), wherein the new position coordinates of the first epsilon {1,2, …, N } scattering points are

And a ninth step, calculating the distance r _l (t) = ||L' "(L,:) |from the first scattering point to the radar.

And tenth, calculating the radar echo s (t) of the simulated satellite model under the integral rotation composite vibration according to the formula for calculating the radar echo data.

As a second example, a solar panel is described as rotating along a long axis.

In order to obtain enough electric energy, the solar sailboard slowly rotates according to the self posture when the satellite runs in an orbit so as to ensure that the solar sailboard is always oriented to the sun.

In this example, the motion model of the satellite solar array turning along the long axis established by the present application is shown in fig. 6, where the centroid O of the target moves to point O' and the target scattering point P moves to point p″ over time t. To facilitate analysis, the motion process of the P point is decomposed into velocityTranslational movement to point P' and then at angular velocity/>From point P' to point p″.

In one embodiment of the application, radar echo data is calculated under a motion model in which a solar array rotates along a long axis, comprising the steps of: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system; dividing all scattering points into a solar sailboard scattering point and a satellite component scattering point except the solar sailboard; calculating first partial radar echo data of the solar panel rotating along the long axis based on the solar panel scattering points; calculating second partial radar echo data of the solar panel rotating along the long axis based on the satellite component scattering points except the solar panel; and adding the first part of radar echo data of the solar panel rotating along the long axis and the second part of radar echo data of the solar panel rotating along the long axis to obtain radar echo data of the solar panel rotating along the long axis.

Second, setting the initial attitude angle of the satellite in the radar coordinate system as(Phi is roll angle, theta is pitch angle, phi is yaw angle), initial distance/>Translational velocity/>

And thirdly, dividing the satellite scattering points into two parts of solar sailboard scattering points and other satellite parts, wherein the first part comprises translation and rotation, and the second part only comprises translation.

Fourth, the first partial echo data s ₁ (t) is calculated by referring to the third, fourth, and seventh to tenth steps in the first example. Specifically, the time t is elapsed, and the rotation angle of the scattering pointThe resulting rotation matrix is shown below:

then, after the motion is performed, the position coordinates/>, of the first part scattering points at the moment t are calculated Then according to the initial attitude angle/>, of the satelliteConverting satellite position coordinates into a reference coordinate system (X, Y, Z), the new position coordinates of any one of the first partial scattering points being calculated by: /(I)Wherein,

Then according to the current scattering point position L', the satellite initial distance/>And satellite translational velocity/>Converting the satellite position coordinates into a radar coordinate system (U, V, W), then calculating new position coordinates of any one scattering point in the first part of scattering points by the following formula:

And calculate the scattering point to radar distance by the following formula: r _l (t) = ||l' "(L,:) | and finally calculating first partial echo data s ₁ (t) of the solar panel rotating along the long axis according to a formula for calculating radar echo data.

Fifth, the second partial scattering points calculate the generated second partial echo data s ₂ (t) with reference to the calculation methods of the seventh to tenth steps in the above first example. Specifically, according to the initial attitude angle of the satelliteConverting satellite position coordinates into a reference coordinate system (X, Y, Z), and calculating new position coordinates of any scattering point in the second part of scattering points by the following formula: /(I)Wherein,

Then according to the current scattering point position L', the satellite initial distance/>And satellite translational velocity/>Converting satellite position coordinates into a radar coordinate system (U, V, W), then the new position coordinates of any one of the second part of scattering points are/>And calculating the distance r _l (t) = ||L' "(L,:||) from the scattering point to the radar, and finally calculating second partial echo data s ₂ (t) of the solar panel rotating along the long axis according to a formula for calculating radar echo data.

And sixthly, superposing the two echo signals to obtain radar echo s (t) =s ₁(t)+s₂ (t) of the simulated satellite solar panel rotating along the long axis.

As a third example, a solar array deployment will be described.

In this example, to study radar returns of satellite solar array deployment, it is assumed that the satellite has two solar arrays on the left and right, each solar array has 3 identical sub-arrays, and a solar array deployment motion model of 3 connected components is created as shown in fig. 7. Wherein the centroid O of the target moves to point O' and the target scattering point P moves to point P "over time t. To facilitate analysis, the motion process of the P point is decomposed into velocityTranslation occurs to point P 'and then rotation occurs from point P' to point p″ at an angular spread velocity ω. In this example, the radar echo of the satellite solar panel expansion is simulated, and the long axis of the solar panel is set to be the y axis under the satellite body coordinate system, so that the solar panel expansion angle rate is omega.

In one embodiment of the application, radar echo data is calculated under a motion model of solar array deployment, comprising the steps of: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system; dividing all scattering points into a solar sailboard scattering point and a satellite component scattering point except the solar sailboard; calculating a fifth position coordinate of a scattering point of the solar panel at the current moment according to the length of the sub-panel and the unfolding angle of the solar panel at the current moment; calculating first partial radar echo data of solar array expansion based on fifth position coordinates of the solar array scattering points; calculating second partial radar echo data of the solar array expansion based on sixth position coordinates of satellite component scattering points except the solar array; and adding the first part of radar echo data of the solar array and the second part of radar echo data of the solar array to obtain radar echo data of the solar array.

Specifically, in a first step, radar basic parameters are set: center frequency f ₀, observation period T, sampling frequency f _s.

Dividing the satellite scattering points into two parts of solar sailboard scattering points and other satellite components, wherein the first part comprises translational motion and unfolding motion, the second part only has translational motion, and the position coordinates of the first part scattering points and the second part scattering points under a body coordinate system are respectively as follows:

Fourth, under the satellite body coordinate system, a kinematic model of the solar sailboard shown in fig. 8 is established, the model can show the positions of the points of the solar sailboard, after the expansion movement of the time t, the coordinate of the joint 1 is constant to be (x ₁,y₁,z₁), and the expansion angle of the solar sailboard is constant The coordinates of the joint 2 are determined by the following formula:

(x₂,y₂,z₂)＝(x₁,y₁+Csin(wt),z₁+Ccos(wt))，

the coordinates of the joint 3 are determined by the following formula:

(x₃,y₃,z₃)＝(x₂,y₂+Csin(wt),z₂-Ccos(wt))

wherein C is the length of the solar sailboard. It should be noted that, in the embodiment of the present application, each joint may include a plurality of scattering points, where the x-axis position coordinates and the y-axis position coordinates of the different scattering points are different, and the z-axis position coordinates are the same, and the movement modes are the same.

For the scattering points on the solar sailboard except for the joint points, the coordinates of the scattering points can be calculated according to the coordinate formulas of the joint 2 and the joint 3, and only the length C' from the current scattering point to the previous joint point is needed to be changed. Therefore, according to the solar panel motion model and the coordinate calculation formulas of the joints 2 and 3, the position coordinates L ₁' of the scattering point of the solar panel at the time t can be obtained.

Fifth, the first partial echo data s ₁ (t) is calculated by referring to the first partial scattering points, i.e. the solar array scattering points, and referring to the calculation methods of the seventh to tenth steps in the first example. Specifically, according to the initial attitude angle of the satelliteConverting satellite position coordinates into a reference coordinate system (X, Y, Z), and calculating new position coordinates of any one scattering point of the solar sailboard scattering points by the following formula: /(I)Wherein,

And calculate the scattering point to radar distance by the following formula: r _l (t) = ||l' "(L,:) | and finally calculating the first partial echo data s ₁ (t) under the solar array according to the formula for calculating radar echo data.

A sixth step of calculating second partial echo data s ₂ (t) by referring to the second partial scattering points, that is, the scattering points of the remaining satellite parts excluding the solar array, in the calculation manner of the seventh to tenth steps in the first example. Specifically, according to the initial attitude angle of the satelliteConverting satellite position coordinates into a reference coordinate system (X, Y, Z), and calculating new position coordinates of any one scattering point of the rest satellite component scattering points by the following formula: /(I)Wherein,

It should be noted that, the new position coordinate of any one of the scattering points of the remaining satellite components, that is, the sixth position coordinate, is the position coordinate of the remaining satellite components after the solar sailboard is unfolded for the time t, specifically, the movement performed by the remaining satellite components in practical application, for example, the translational movement or the rotational calculation may be performed, and the specific calculation mode may refer to the coordinate calculation mode in the related movement, which is not described herein again.

Further, based on the current scattering point position L', the initial distance of the satelliteAnd satellite translational velocity/>Converting the satellite position coordinates into a radar coordinate system (U, V, W), then calculating new position coordinates of any one scattering point in the second part of scattering points by the following formula:

and calculate the scattering point to radar distance by the following formula: r _l (t) = ||l' "(L,:) | and finally calculating second partial echo data s ₂ (t) under the solar array according to a formula for calculating radar echo data.

And seventhly, superposing the two radar echoes to obtain a radar echo s (t) =s ₁(t)+s₂ (t) expanded by the simulated satellite solar array.

As a fourth example, an antenna deployment compound rotation will be described.

In order to ensure efficient transmission of signals, the satellite antenna needs to be aligned with the target direction during operation. The satellite antenna is initially set to a stowed state, the antenna is deployed over time along the bottom connection point, and the antenna is rotated facing in the target direction.

In this example, the motion model of the antenna deployment compound rotation established by the present application is shown in fig. 9, where the centroid O of the target moves to point O "and the target scattering point P moves to point P'" over time t. To facilitate analysis, the motion process of the P point is decomposed into velocityTranslation to point P' and then at angular velocity of expansion/>Moving from point P' to point P ", finally at angular velocity/>From point P "to point P'". In this example, the satellite antenna is simulated to develop a composite rotated radar echo.

In one embodiment of the application, radar echo data is calculated under a motion model of antenna deployment compound rotation, comprising the steps of: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system, and a satellite antenna unfolding angular speed, a bottom connection point coordinate and an antenna rotation angular speed of the satellite under a target body coordinate system; dividing all scattering points into antenna scattering points and satellite component scattering points except for the antenna; calculating a seventh position coordinate of an antenna scattering point at the current moment according to the satellite antenna spreading angular speed, the bottom connecting point coordinate and the antenna rotating angular speed; calculating first partial radar echo data of the antenna unfolding composite rotation based on seventh position coordinates of the antenna scattering points; calculating second partial radar echo data of the antenna unfolding composite rotation based on eighth position coordinates of satellite component scattering points except the antenna; and adding the first part of radar echo data of the antenna unfolding composite rotation and the second part of radar echo data of the antenna unfolding composite rotation to obtain radar echo data of solar array unfolding.

Second, setting the initial attitude angle of the satellite in the radar coordinate system as(Phi is roll angle, theta is pitch angle, phi is yaw angle), initial distance/>Translational velocity/>Bottom connection point coordinates

The third step, dividing the satellite scattering points into two parts of antenna scattering points and other satellite components, wherein the first part, namely the antenna scattering points, comprises translational motion and unfolding composite rotation, the second part, namely other satellite components except the antenna, only has translational motion, and the position coordinates of the first part scattering points and the second part scattering points under a body coordinate system are respectively as follows:

Fourth, in this example, the antenna performs the unfolding compound rotation, so after the moment t, the position coordinate of any scattering point in the first part of the current observation moment is calculated by the following formula:

Fifth, the first partial echo data s ₁ (t) is calculated by referring to the first partial scattering points, i.e., the antenna scattering points, by referring to the calculation methods of the seventh to tenth steps in the above first example. Specifically, according to the initial attitude angle of the satellite Converting satellite position coordinates into a reference coordinate system (X, Y, Z), and calculating new position coordinates of any one of the antenna scattering points by the following formula: /(I)Wherein,

And calculate the scattering point to radar distance by the following formula: r _l (t) = ||l' "(L,:) | and finally calculating the first partial echo data s ₁ (t) under the antenna deployment composite rotation according to the formula for calculating the radar echo data.

A sixth step of calculating second partial echo data s ₂ (t) by referring to the second partial scattering points, i.e., the scattering points of the rest of the satellite components except the antenna, with reference to the calculation methods of the seventh to tenth steps in the above-described first example. Specifically, according to the initial attitude angle of the satelliteConverting satellite position coordinates into a reference coordinate system (X, Y, Z), and calculating new position coordinates of any one scattering point of the other satellite component scattering points except the antenna by the following formula: /(I)Wherein,

It should be noted that, the new position coordinate of any one of the scattering points of the other satellite components except the antenna, that is, the eighth position coordinate, is the position coordinate of the other satellite components after the antenna expands the composite rotation motion t time, specifically, the calculation may be performed according to the motion performed by the other satellite components in the practical application, for example, the rotation, and the specific calculation manner may refer to the coordinate calculation manner in the rotation, which is not described herein again.

/>

And calculate the scattering point to radar distance by the following formula: r _l (t) = ||l' "(L,:) | and finally calculating second partial echo data s ₂ (t) under the antenna unfolding composite rotation according to a formula for calculating radar echo data.

And seventhly, superposing the two radar echoes to obtain the radar echo s (t) =s ₁(t)+s₂ (t) of the antenna unfolding composite rotation.

Therefore, modeling analysis is carried out on four typical micro motions of the artificial satellite, and radar echo data of each motion under filling are obtained.

And 103, performing time-frequency analysis on the radar echo data of each satellite micro-motion to acquire a time-frequency spectrogram of each satellite micro-motion.

Specifically, time-frequency analysis is sequentially performed on the acquired radar echo data of each micro motion, so that a time-frequency spectrogram of a radar echo data signal can be obtained.

In one embodiment of the present application, the time-frequency analysis may be performed by short-time fourier transform, and in a specific implementation, the time-frequency analysis may be performed on the radar echo data of each of the satellite micro motions by the following formula:

T_s(t,ω)＝∫s(τ)w(τ-t)e^-jωτdτ

where w (t) is a window function and s (t) is radar echo data.

Therefore, the simulation method provided by the embodiment of the application simulates the micro Doppler effect caused by the micro motion of the satellite, displays the time-frequency spectrograms under different micro motion states, is favorable for further in-depth research on the micro motion of the satellite, and can monitor the micro motion of the satellite more accurately and efficiently.

In summary, according to the radar signal simulation method for the micro motion state of the artificial satellite in the embodiment of the application, a three-dimensional simulation model of the satellite scattering points is built based on a preset number of scattering points, then a plurality of satellite micro motions to be simulated are determined, a motion model is built for each satellite micro motion respectively, radar echo data of the current satellite micro motion is calculated under each motion model, and finally time-frequency analysis is performed on the radar echo data of each satellite micro motion to obtain a time-frequency spectrogram of each satellite micro motion. Therefore, the method can simulate the micro Doppler effect caused by the micro motion of the satellite, displays time-frequency spectrograms under different micro motion states, solves the technical problem that the micro motion of the space target is deeply researched due to the fact that the radar specially used for monitoring and sensing the space target is lacked in the related technology and the accumulated radar echo data quantity is insufficient, can be researched by the simulation technology, can acquire the fine characteristics of the satellite by researching the micro motion state of the satellite with lower cost, provides theoretical support for designing a more efficient satellite monitoring system, and is beneficial to monitoring the micro motion of the satellite more accurately and efficiently.

In order to more clearly describe the specific implementation process of the radar signal simulation method for the micro-motion state of the artificial satellite in the embodiment of the application, the following specific embodiment is described, and the embodiment comprises the following three steps:

Step one, a three-dimensional simulation model of satellite scattering points is established.

The satellite prototype constructed by the simulation of the application is shown in fig. 2, wherein the satellite is 32m long, 4m wide and 8m high (solar sailboard and antenna unfolding state). A three-dimensional scattering point model was built in MATLAB software according to satellite shape and size, as shown in fig. 3. The simulated satellite sets 125 scattering points, namely N=125, and the initial position matrix is as follows

It should be noted that, scattering points of key components such as the satellite main body, the solar sailboard and the antenna are individually grouped so as to facilitate the next generation of radar echoes caused by micro-motions of the key components.

And step two, satellite micro-motion modeling.

This embodiment designs 4 typical satellite micro-motions: ① The satellite integrally rotates and compound the vibration, ② solar arrays rotate along the long axis, ③ solar arrays are unfolded, and ④ antennas are unfolded and compound the rotation, and other micro-motion simulation can be expanded according to the method.

① For the overall rotation and compound vibration of the satellite, the method comprises the following steps:

1) Setting radar basic parameters: center frequency f ₀ =14 GHz, observation period t=100 s, sampling frequency f _s =200 Hz;

2) Setting initial attitude angle of satellite in radar coordinate system Initial distance/>Translational velocity/>Instantaneous rotational angular velocity/>, under satellite body coordinate systemVibration frequency f=0.01 Hz, vibration amplitude a=1m, vibration direction/>

3) Over time t, rotation angle of scattering pointObtaining a rotation matrix:

4) Scattering point position coordinates at time t

5) The vibration distance at the time t;

6) Updating the position coordinates of the scattering point at the current observation time

7) According to the initial attitude angle of the satelliteConverting satellite position coordinates into a reference coordinate system (X, Y, Z), new position coordinates/>Wherein,

8) Based on the current scattering point position L', the initial distance of the satelliteAnd satellite translational velocity/>Converting satellite position coordinates into a radar coordinate system (U, V, W), wherein the new position coordinates of the first epsilon {1,2, …,125} scattering points are as follows:

L″′(l，：)＝L″(l，：)+[800000，350000，250000]+[10t，5t，0]

9) Calculate the L-th scattering point-to-radar distance r _l (t) = |l' "(L,: ) I;

10 And obtaining the radar echo s (t) simulating the integral rotation compound vibration of the satellite according to the radar echo data calculation formula.

② For rotation of the solar array along the long axis, the method comprises the following steps:

2) Setting initial attitude angle of satellite in radar coordinate system Initial distance/>Translational velocity/>Solar sailboard rotation angular velocity/>, under satellite body coordinate system

3) Dividing a satellite scattering point into a solar sailboard scattering point and two scattering points of other satellite components, wherein the first part comprises translation and rotation, and the second part only comprises translation;

4) First partial scatter point reference ①, step 3), step 4), and steps 7) to 10) produce first partial echo data s ₁ (t);

5) Second partial scatter point references ①, steps 7) to 10) produce second partial echo data s ₂ (t);

6) And superposing the two echo signals to obtain radar echo s (t) =s ₁(t)+s₂ (t) of the simulated satellite solar sailboard rotating along the long axis.

③ For solar array deployment, comprising the steps of:

2) Setting initial attitude angle of satellite in radar coordinate system Initial distance/>Translational velocity/>Solar sailboard expansion angular rate/>, under satellite body coordinate system

3) Dividing the satellite scattering points into two parts of solar sailboard scattering points and other satellite components, wherein the first part comprises translational motion and unfolding motion, the second part only comprises translational motion, and the position coordinates of the second part under a body coordinate system are respectively as follows:

4) In the satellite body coordinate system, the kinematic model of the solar sailboard is shown in fig. 8, and the length of the sub sailboard is c=4m. The coordinate of the joint 1 is constant to be (x ₁,y₁,z₁) ≡ (0,4,0), and the solar sailboard unfolding angle is adjusted according to the current moment The coordinates of the joint 2 and the joint 3 are respectively:

Wherein each joint can contain a plurality of scattering points, the position coordinates of the different scattering points on the x-axis are different, the position coordinates on the y-axis and the z-axis are the same, and the movement modes are the same. Without loss of generality, 1 scatter point may be taken as an example at each joint. For the scattering points except the joint points on the solar sailboard, the calculation can be performed according to the coordinate calculation formulas of the joint 2 and the joint 3, and only the length of the sub sailboard is changed into the length C' from the front scattering point to the previous joint. Thereby, the position coordinate L ₁' of the scattering point of the solar panel at the moment t can be obtained.

5) Generating first partial echo data s ₁ (t) according to the position coordinates L ₁' of the scattering points of the solar sailboard and referring to the step 7) to the step 10) in ①;

6) Second partial scattering point position coordinates L ₂' referring to step 7) to step 10) in ①) generate second partial echo data s ₂ (t);

7) And superposing the two radar echoes to obtain the radar echo s (t) =s ₁(t)+s₂ (t) unfolded by the simulated satellite solar sailboard.

④ For the antenna unfolding composite rotary motion, the method comprises the following calculation steps:

2) 2) setting an initial attitude angle of the satellite in a radar coordinate system Initial distance/>Translational velocity/>Angular velocity of satellite antenna expansion/>, under satellite body coordinate systemBottom tie point coordinates/>Angular velocity of antenna rotation/>

3) Dividing the satellite scattering points into an antenna scattering point and other satellite component scattering points, wherein the first part comprises translational motion and unfolding composite rotation, and the second part only comprises translational motion, and the position coordinates of the second part under a body coordinate system are respectively as follows:

4) Considering the unfolding composite rotation, the position coordinates of the first part of scattering points at the current observation time are as follows

5) The first partial scattering points L ₁' refer to steps 7) to 10) in ①) to generate first partial echo data s ₁ (t);

6) Second partial scattering points L ₂ produce second partial echo data s ₂ (t) with reference to steps 7) to 10) in ①;

7) And superposing the two radar echoes to obtain the radar echo s (t) =s ₁(t)+s₂ (t) of the unfolding composite rotation of the simulated satellite antenna.

And thirdly, performing time-frequency analysis on radar echoes in four micro-motion states, and obtaining a time-frequency spectrogram corresponding to each micro-motion.

Specifically, the acquired radar echo data of the four micro motions are sequentially subjected to time-frequency analysis, so that a time-frequency spectrogram of the overall rotation composite vibration of the satellite shown in fig. 10, a time-frequency spectrogram of the rotation of the satellite solar array along the long axis shown in fig. 11, a time-frequency spectrogram of the unfolding of the satellite solar array shown in fig. 12, and a time-frequency spectrogram of the unfolding composite rotation of the satellite antenna shown in fig. 13 can be sequentially obtained.

The Time (Time) is in seconds on the abscissa and the Doppler (Doppler) is in hertz on the ordinate in the several Time-frequency spectra described above.

In order to implement the above embodiment, the present application further provides a radar signal simulation device for the micro-motion state of the satellite, and fig. 14 is a schematic structural diagram of the radar signal simulation device for the micro-motion state of the satellite according to the embodiment of the present application.

As shown in fig. 14, the apparatus includes a setup module 100, a calculation module 200, and an analysis module 300.

The establishing module 100 is configured to establish a satellite scattering point three-dimensional simulation model based on a preset number of scattering points, where each preset component in the satellite scattering point three-dimensional simulation model has a corresponding scattering point group.

The computing module 200 is configured to determine a plurality of satellite micro motions to be simulated, establish a radar coordinate system, a target body coordinate system and a reference coordinate system, respectively establish a motion model for each satellite micro motion, calculate a distance from each scattering point to a radar under each motion model, and calculate radar echo data of a current satellite micro motion according to the distance from each scattering point to the radar, where the plurality of satellite micro motions include: the satellite integrally rotates and compound vibrates, the solar panel rotates along the long axis, and the solar panel expands and the antenna expands and compound rotates.

The analysis module 300 is configured to perform time-frequency analysis on the radar echo data of each satellite micro-motion, and obtain a time-frequency spectrogram of each satellite micro-motion.

Optionally, in one embodiment of the present application, the computing module 200 is specifically configured to: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system, and an instantaneous rotational angular speed, a vibration frequency, a vibration amplitude and a vibration direction of the satellite under a target body coordinate system; acquiring a rotation matrix according to the rotation angular speed, and calculating a first position coordinate of any scattering point at the current moment according to the rotation matrix; calculating the vibration distance at the current moment according to the vibration frequency, the vibration amplitude and the vibration direction, and updating the first position coordinate into a second position coordinate according to the vibration distance; converting the second position coordinate into the reference coordinate system according to the initial attitude angle, and acquiring a third position coordinate of any scattering point; according to the initial distance and the translation speed, converting the third position coordinate into a radar coordinate system, obtaining a fourth position coordinate of any scattering point, and calculating the distance from any scattering point to the radar according to the fourth position coordinate; and calculating radar echo data of the integral rotation composite vibration of the satellite according to the distance from each scattering point to the radar.

It should be noted that the foregoing description of the embodiments of the radar signal simulation method for the micro-motion state of the satellite is also applicable to the radar signal simulation device for the micro-motion state of the satellite in this embodiment, and the implementation principle is similar, and will not be repeated here.

In summary, the radar signal simulation device for the micro motion state of the artificial satellite according to the embodiment of the application can simulate the micro doppler effect caused by micro motion of the satellite, and display time-frequency spectrograms under different micro motion states, so that the technical problems that the lack of radar specially used for micro motion monitoring sensing of a space target in the related technology and the accumulated radar echo data volume are insufficient, which limit the deep research on the micro motion of the space target are solved, the micro motion state of the satellite is researched through the simulation technology, the fine characteristics of the satellite can be researched and obtained with lower cost, theoretical support is provided for designing a more efficient satellite monitoring system, and the micro motion of the satellite is more accurately and efficiently monitored.

In order to achieve the above embodiments, the present application further proposes a non-transitory computer readable storage medium, on which a computer program is stored, which when executed by a processor implements a radar signal simulation method for a micro-motion state of an artificial satellite according to an embodiment of the first aspect of the present application.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some 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 present application. In this specification, schematic representations of the above terms are not necessarily directed 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. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and additional implementations are included within the scope of the preferred embodiment of the present application in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order from that shown or discussed, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the embodiments of the present application.

Logic and/or steps represented in the flowcharts or otherwise described herein, e.g., a ordered listing of executable instructions for implementing 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). In addition, the computer readable medium may even be paper or other suitable medium on which the program is printed, as the program may 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 is to be understood that portions of the present application may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, the various steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. As with the other embodiments, if implemented in hardware, may be implemented using any one or combination of the following techniques, as is well known in the art: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like.

Those of ordinary skill in the art will appreciate that all or a portion of the steps carried out in the method of the above-described embodiments may be implemented by a program to instruct related hardware, where the program may be stored in a computer readable storage medium, and where the program, when executed, includes one or a combination of the steps of the method embodiments.

In addition, each functional unit in the embodiments of the present application may be integrated in one processing module, or each unit may exist alone physically, or two or more units may be integrated in one module. The integrated modules may be implemented in hardware or in software functional modules. The integrated modules may also be stored in a computer readable storage medium if implemented in the form of software functional modules and sold or used as a stand-alone product.

The above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, or the like. While embodiments of the present application have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the application, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the application.

Claims

1. A radar signal simulation method aiming at a micro-motion state of an artificial satellite is characterized by comprising the following steps:

Determining a plurality of satellite micro motions to be simulated, establishing a radar coordinate system, a target body coordinate system and a reference coordinate system, respectively establishing a motion model for each satellite micro motion, calculating the distance from each scattering point to a radar under each motion model, and calculating radar echo data of the current satellite micro motion according to the distance from each scattering point to the radar, wherein the plurality of satellite micro motions comprise: the satellite integrally rotates and compound the vibration, the solar panel rotates along the long axis, the solar panel expands and the antenna expands and compound the rotation; calculating radar echo data under a motion model of the satellite integral rotation composite vibration, including: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system, and an instantaneous rotational angular speed, a vibration frequency, a vibration amplitude and a vibration direction of the satellite under a target body coordinate system; acquiring a rotation matrix according to the rotation angular speed, and calculating a first position coordinate of any scattering point at the current moment according to the rotation matrix; calculating a vibration distance at the current moment according to the vibration frequency, the vibration amplitude and the vibration direction, and updating the first position coordinate into a second position coordinate according to the vibration distance; converting the second position coordinate into the reference coordinate system according to the initial attitude angle, and acquiring a third position coordinate of any scattering point; converting the third position coordinate into the radar coordinate system according to the initial distance and the translation speed, acquiring a fourth position coordinate of any scattering point, and calculating the distance between any scattering point and the radar according to the fourth position coordinate; calculating radar echo data of the whole rotation compound vibration of the satellite according to the distance from each scattering point to the radar; calculating radar echo data under a motion model in which the solar array rotates along a long axis, wherein the radar echo data comprises: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system; dividing all scattering points into a solar panel scattering point and a satellite component scattering point except for the solar panel; calculating first partial radar echo data of the solar sailboard rotating along the long axis based on the solar sailboard scattering points; calculating second partial radar echo data of the solar panel rotating along the long axis based on the satellite component scattering points except the solar panel; adding the first part of radar echo data of the solar array rotating along the long axis and the second part of radar echo data of the solar array rotating along the long axis to obtain radar echo data of the solar array rotating along the long axis; wherein the radar echo data is calculated by the following formula:

Wherein sigma _l (t) is an echo amplitude modulation coefficient of the scattering point, c is a propagation speed of electromagnetic wave, and r _l (t) is a distance from the scattering point to the radar;

2. The method of claim 1, wherein calculating radar echo data under a motion model of the solar array deployment comprises:

Setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system;

Dividing all scattering points into a solar panel scattering point and a satellite component scattering point except for the solar panel;

calculating a fifth position coordinate of a scattering point of the solar panel at the current moment according to the length of the sub-panel and the unfolding angle of the solar panel at the current moment;

calculating first partial radar echo data of solar panel expansion based on fifth position coordinates of the solar panel scattering points;

Calculating second partial radar echo data of solar array expansion based on sixth position coordinates of satellite component scattering points except the solar array;

And adding the first part of radar echo data of the solar array expansion and the second part of radar echo data of the solar array expansion to obtain radar echo data of the solar array expansion.

3. The method of claim 1, wherein calculating radar echo data under a motion model of the antenna deployment compound rotation comprises:

Setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system, and a satellite antenna unfolding angular speed, a bottom connection point coordinate and an antenna rotation angular speed of the satellite under a target body coordinate system;

dividing all scattering points into antenna scattering points and satellite component scattering points except for the antenna;

Calculating a seventh position coordinate of an antenna scattering point at the current moment according to the angular velocity of satellite antenna expansion, the bottom connection point coordinate and the angular velocity of antenna rotation;

Calculating first partial radar echo data of the antenna unfolding composite rotation based on seventh position coordinates of the antenna scattering points;

Calculating second partial radar echo data of the antenna unfolding composite rotation based on eighth position coordinates of satellite component scattering points except the antenna;

And adding the first part of radar echo data of the antenna unfolding composite rotation and the second part of radar echo data of the antenna unfolding composite rotation to obtain the radar echo data of the solar array unfolding.

4. The method of claim 1, wherein the radar echo data for each of the satellite micro-motions is time-frequency analyzed by the following formula:

T_s(t,ω)＝∫s(τ)w(τ-t)e^-jωτdr

where w (t) is a window function and s (t) is radar echo data.

5. Radar signal simulation device for the micro-motion state of a satellite, applied to the radar signal simulation method for the micro-motion state of a satellite according to any one of claims 1to 4, characterized in that it comprises:

the analysis module is used for carrying out time-frequency analysis on the radar echo data of each satellite micro-motion and obtaining a time-frequency spectrogram of each satellite micro-motion;

The computing module is specifically configured to:

setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite under a radar coordinate system, and an instantaneous rotational angular speed, a vibration frequency, a vibration amplitude and a vibration direction of the satellite under a target body coordinate system;

acquiring a rotation matrix according to the rotation angular speed, and calculating a first position coordinate of any scattering point at the current moment according to the rotation matrix;

Calculating a vibration distance at the current moment according to the vibration frequency, the vibration amplitude and the vibration direction, and updating the first position coordinate into a second position coordinate according to the vibration distance;

Converting the second position coordinate into the reference coordinate system according to the initial attitude angle, and acquiring a third position coordinate of any scattering point;

Converting the third position coordinate into the radar coordinate system according to the initial distance and the translation speed, acquiring a fourth position coordinate of any scattering point, and calculating the distance between any scattering point and the radar according to the fourth position coordinate;

And calculating radar echo data of the integral rotation composite vibration of the satellite according to the distance from each scattering point to the radar.

6. A non-transitory computer readable storage medium having stored thereon a computer program, wherein the computer program when executed by a processor implements the radar signal simulation method for satellite dish as claimed in any of claims 1-4.