CN114254485A - Radar signal simulation method for micro-motion state of artificial satellite - Google Patents

Radar signal simulation method for micro-motion state of artificial satellite Download PDF

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CN114254485A
CN114254485A CN202111426242.3A CN202111426242A CN114254485A CN 114254485 A CN114254485 A CN 114254485A CN 202111426242 A CN202111426242 A CN 202111426242A CN 114254485 A CN114254485 A CN 114254485A
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CN114254485B (en
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李刚
赵志纯
焦健
王建文
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Tsinghua University
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Abstract

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

Description

Radar signal simulation method for micro-motion 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 aerospace equipment technology, the new generation of satellites can not only rotate the antenna, unfold and fold the solar sailboard and the like, but also perform complex operations such as quick maneuvering orbital transfer, mechanical arm grabbing and the like. However, as the number of on-orbit satellites is increasing, the risk of space debris collision is increased sharply, maneuvering avoidance is performed to avoid collision, and each avoidance operation needs to consume more resources. In the face of increasingly complex and variable space safety environment, especially with the low-orbit large-scale constellation explosion and the enhancement of the function ambiguity of a space system, an unprecedented challenge is brought to a space situation perception system of a satellite.
In the related art, the monitoring means for the space targets such as the artificial satellite cannot achieve seamless coverage of the space domain and the time domain, the detection distance and the detection precision are low, and abundant actual data cannot be acquired for research and judgment of the space targets such as the artificial satellite, so that research on the artificial satellite motion state simulation technology is necessary to be carried out, and technical support is provided for monitoring and sensing of the artificial satellite motion state simulation technology. The radar has all-weather detection capability all day long and is one of the indispensable important means for artificial satellite monitoring and sensing, and the radar characteristic signal is the basis for radar target identification.
In addition, small motions such as rotation, vibration, precession and the like of a spatial object or a component of an object besides the translation of a body are called micro motions, and basic micro motion types involved in typical micro motion behaviors of a satellite include rotation, vibration, precession and the like. The micro-motion of the target reflects the fine characteristics of the target, has important value and is widely concerned in the field of radar detection and identification.
However, due to the lack of radar dedicated to spatial target micro-motion monitoring sensing, the amount of accumulated radar echo data is insufficient, and further research in the field is limited to a certain extent. Therefore, a method for simulating a radar signal in a satellite micro-motion state is needed to provide support for designing a more efficient satellite monitoring system.
Disclosure of Invention
The present application is directed to solving, at least to some extent, one of the technical problems in the related art.
Therefore, a first objective of the present application is to provide a method for simulating a radar signal in a satellite micro-motion state, which can simulate a micro-doppler effect caused by micro-motion of a satellite, and display time-frequency spectrograms in different micro-motion states, so as to solve the problems that a radar dedicated for micro-motion monitoring and sensing of a spatial target is not available at present, the amount of accumulated radar echo data is insufficient, and deep research on micro-motion of the spatial target is limited.
A second object of the present application is to provide a radar signal simulation apparatus for a satellite micro-motion state.
A third object of the present application is to propose a non-transitory computer-readable storage medium.
In order to achieve the above object, a first embodiment of the present application provides a method for simulating a radar signal in a satellite micro-motion state, including the following steps:
establishing a satellite scattering point three-dimensional simulation model based on a preset number of scattering points, wherein each preset component in the satellite scattering point three-dimensional simulation model has a corresponding scattering point group;
determining a plurality of satellite micro motions to be simulated, establishing a radar coordinate system, a target specimen coordinate system and a reference coordinate system, respectively establishing motion models 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 method comprises the following steps of satellite integral rotation composite vibration, solar sailboard rotation along a long axis, solar sailboard unfolding and antenna unfolding composite rotation;
and performing time-frequency analysis on the radar echo data of each satellite micromotion to obtain a time-frequency spectrogram of each satellite micromotion.
Optionally, in an embodiment of the present application, calculating radar echo data under a motion model of the satellite integral rotation compound vibration includes: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite in a radar coordinate system, and an instantaneous rotation angular speed, a vibration frequency, a vibration amplitude and a vibration direction of the satellite in a target specimen 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 of 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 to obtain 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 from any scattering point to a 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 an embodiment of the present application, calculating radar return data under a motion model of the solar windsurfing board rotating along the long axis includes: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite in a radar coordinate system; dividing all scattering points into solar sailboard scattering points and satellite component scattering points except the solar sailboard; calculating first part radar echo data of the solar sailboard rotating along the long axis based on the scattering points of the solar sailboard; calculating a second part of radar echo data of the solar sailboard rotating along the long axis based on the scattering points of the satellite components except the solar sailboard; and adding the first part of radar echo data of the solar sailboard rotating along the long axis and the second part of radar echo data of the solar sailboard rotating along the long axis to obtain the radar echo data of the solar sailboard rotating along the long axis.
Optionally, in an embodiment of the present application, calculating radar return data under the motion model of the solar windsurfing board unfolding comprises: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite in a radar coordinate system; dividing all scattering points into solar sailboard scattering points and satellite component scattering points except the solar sailboard; calculating a fifth position coordinate of a scattering point of the solar sailboard at the current moment according to the length of the sub-sailboard and the unfolding angle of the solar sailboard at the current moment; calculating first part of radar echo data of the unfolding of the solar sailboard based on the fifth position coordinates of the scattering points of the solar sailboard; calculating a second portion of radar echo data of the solar sailboard deployment based on the sixth position coordinates of the scattering points of the satellite components other than the solar sailboard; and adding the first part of radar echo data of the unfolded solar sailboard and the second part of radar echo data of the unfolded solar sailboard to obtain the radar echo data of the unfolded solar sailboard.
Optionally, in an embodiment of the present application, calculating radar echo data under the motion model of the antenna unfolding composite rotation includes: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite in a radar coordinate system, and a satellite antenna deployment angular speed, a bottom connection point coordinate and an antenna rotation angular speed of the satellite in a target specimen coordinate system; dividing all scattering points into antenna scattering points and satellite component scattering points except the antennas; calculating a seventh position coordinate of an antenna scattering point at the current moment according to the satellite antenna unfolding angular velocity, the bottom connection point coordinate and the antenna rotation angular velocity; calculating first part radar echo data of antenna unfolding composite rotation based on seventh position coordinates of the scattering points of the antenna; calculating a second part of radar echo data of antenna expansion composite rotation based on the eighth position coordinate of the scattering point of the satellite component 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 sailboard unfolding.
Optionally, in an embodiment of the present application, the time-frequency analysis is performed on the radar echo data of each satellite micro-motion according to the following formula:
Ts(t，ω)＝∫s(τ)w(τ-t)e-jωτdτ
where w (t) is a window function and s (t) is radar echo data.
Optionally, in an embodiment of the present application, the radar echo data is calculated by the following formula:
Figure BDA0003374998200000031
wherein σl(t) the echo amplitude modulation coefficient of the scattering point, c the propagation velocity of the electromagnetic wave, rlAnd (t) is the distance from the scattering point to the radar.
In order to achieve the above object, a second aspect of the present application provides a radar signal simulation apparatus for a satellite micro-motion state, including the following modules:
the satellite scattering point three-dimensional simulation system comprises an establishing module, a calculating module and a calculating module, wherein the establishing module is used for establishing a satellite scattering point three-dimensional simulation model based on a preset number of scattering points, and each preset component in the satellite scattering point three-dimensional simulation model has a corresponding scattering point group;
the calculation module is used for determining a plurality of satellite micro motions to be simulated, establishing a radar coordinate system, a target specimen 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 method comprises the following steps of satellite integral rotation composite vibration, solar sailboard rotation along a long axis, solar sailboard unfolding and antenna unfolding composite rotation;
and the analysis module is used for performing time-frequency analysis on the radar echo data of each satellite micromotion to obtain a time-frequency spectrogram of each satellite micromotion.
Optionally, in an embodiment of the present application, the calculation 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 in a radar coordinate system, and an instantaneous rotation angular speed, a vibration frequency, a vibration amplitude and a vibration direction of the satellite in a target specimen 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 of 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 to obtain 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 from any scattering point to a 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 micro Doppler effect that this application can the simulation satellite micro motion arouses, and show the time frequency spectrogram under the different micro motion state, it lacks the radar that is exclusively used in space target micro motion monitoring perception to have solved among the correlation technique, the radar echo data volume that accumulates is not enough, lead to having restricted the technical problem to the deep research of the micro motion of space target, through the micro motion state of simulation technology research satellite, can obtain the meticulous characteristic of satellite with lower cost research, for designing more efficient satellite monitoring system provides theoretical support, be favorable to more accurate and efficient monitoring satellite's micro motion.
In order to achieve the above embodiments, the third aspect of the present application further proposes a non-transitory computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the method for simulating a radar signal for a satellite micro-motion state in the above embodiments is implemented.
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 present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a flowchart of a method for simulating a radar signal in a satellite micro-motion state according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a simulation-constructed satellite model 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 disclosure;
fig. 4 is a schematic diagram of a satellite observation geometric model according to an embodiment of the present application;
fig. 5 is a schematic diagram of a geometric model of the integral rotation compound vibration of a satellite according to an embodiment of the present application;
fig. 6 is a schematic view of a geometric model of a satellite solar panel rotating along a long axis according to an embodiment of the present application;
FIG. 7 is a schematic diagram of a geometric model of a satellite solar panel deployment according to an embodiment of the present disclosure;
FIG. 8 is a schematic diagram of a kinematic model of a satellite solar panel deployment according to an embodiment of the present application;
fig. 9 is a schematic diagram of a geometric model of a satellite antenna unfolding composite rotation according to an embodiment of the present application;
fig. 10 is a time-frequency spectrum diagram of a satellite integral rotation composite vibration according to an embodiment of the present application;
fig. 11 is a time-frequency spectrum diagram of a satellite solar panel rotating along a long axis according to an embodiment of the present application;
fig. 12 is a time-frequency spectrum diagram 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 apparatus for a satellite micro-motion state according to an embodiment of the present application.
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 drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
The typical micro-motion behaviors of the satellite include main load actions such as antenna unfolding and folding, antenna or lens rotation and the like, solar panel rotation, fault state rolling and the like, the related basic micro-motion types include rotation, vibration, precession and the like, and the micro-motion of the satellite reflects the fine characteristics of the satellite and has important value. The method and the device for simulating the radar signal of the artificial satellite in the micro-motion state can simulate the micro Doppler effect caused by the micro-motion of the satellite, show time-frequency spectrograms in different micro-motion states, and are beneficial to more accurately and efficiently monitoring the micro-motion of the satellite.
The following describes a method and an apparatus for simulating a radar signal for a satellite micro-motion state according to an embodiment of the present invention with reference to the accompanying drawings.
Fig. 1 is a flowchart of a method for simulating a radar signal in a satellite micro-motion state according to an embodiment of the present invention, as shown in fig. 1, the method includes the following steps:
step 101, establishing a satellite scattering point three-dimensional simulation model based on a preset number of scattering points, wherein each preset component in the satellite scattering point three-dimensional simulation model has a corresponding scattering point group.
The preset number of scattering points can be determined as different values according to actual requirements, for example, the number of scattering points is determined according to actual factors such as the shape and size of the satellite, the accuracy requirement of simulation and the like.
In one embodiment of the application, a satellite model is firstly built in simulation software, and then scattering points of a simulation satellite are set according to a built satellite prototype, so that a satellite scattering point three-dimensional simulation model is built according to a determined number of scattering points.
For example, as shown in fig. 2, a satellite prototype constructed by simulation in the present application includes a satellite main 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 a solar panel and an antenna unfolding state. Then, a three-dimensional scattering point model is established in simulation software according to the shape and size of the satellite, the simulation satellite is provided with N scattering points, the N scattering points are correspondingly arranged according to the prototype of the satellite, the three-dimensional simulation model of the satellite scattering points shown in the figure 3 is formed by the scattering points, and an initial position matrix obtained by the initial positions of the scattering points is as follows:
Figure BDA0003374998200000061
it should be noted that each preset component in the satellite scattering point three-dimensional simulation model constructed in the present application has a corresponding scattering point group, where the preset component may be a key component in the satellite, that is, a main component of the satellite performing micro-motion, and in the present application, the scattering points of each key component are independently grouped so as to subsequently generate a radar echo caused by the micro-motion of the key component, and the accuracy of the obtained radar echo caused by the micro-motion of the key component is improved by separating from other components. In one embodiment of the present application, the radar reflection intensity σ of the scattering point may also be determined according to the shape and material of each component of the satellite.
102, determining a plurality of satellite micro motions to be simulated, establishing a radar coordinate system, a target specimen 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 integral rotation compound vibration, the solar array rotation along the long axis, the solar array expansion and the antenna expansion compound rotation.
For the convenience of clearly describing the simulation method of the present application, the embodiment of the present application uses a plurality of satellite micro motions including: the satellite integral rotation composite vibration, the solar panel rotation along the long axis, the solar panel expansion and the antenna expansion composite rotation are taken as examples for explanation. Of course, the simulation of other micro motions can also be expanded according to the radar signal simulation method for the micro motion state of the artificial satellite.
It should be noted that, based on the established scattering point model, the radar echo can be regarded as being formed by overlapping echoes of scattering points forming a target moving part, so that the motion model is respectively established for each satellite micromotion, the distance from each scattering point to the radar is calculated under each motion model, the echo data of the scattering points is calculated according to the distance from each scattering point to the radar, the radar echo data of the current satellite micromotion can be acquired after the echo data of each scattering point are overlapped, and the micromotion state can be conveniently researched according to the radar echo data in each motion state.
It should be further noted that, in order to facilitate the calculation of echo data under a plurality of different motion models, a radar coordinate system, a target specimen coordinate system and a reference coordinate system suitable for each motion model are established first. In specific implementation, as a possible implementation manner, as shown in fig. 4, a spatial target rotation observation geometric model is first established, and it is assumed that a target (e.g., a satellite) translates and rotates relative to a stationary radar, where the observation radar is located at an origin Q of a radar coordinate system (U, V, W), and a body coordinate system (x, y, z) is established with a target centroid O as an origin, where the coordinate system changes along with the movement of the target. In order to facilitate the analysis of the target movement, a reference coordinate system (X, Y, Z) is introduced, wherein the origin of the reference coordinate system coincides with the origin of the target specimen coordinate system and is parallel to the radar coordinate system, and the reference coordinate system (X, Y, Z) and the target specimen coordinate system (X, Y, Z) have the same translation component but do not contain a rotation component with respect to the fixed radar coordinate system (U, V, W).
In the embodiment of the present application, if there are N scattering points in the satellite, the distance between any ith scattering point and the radar can be represented by the following formula:
Figure BDA0003374998200000071
wherein the content of the first and second substances,
Figure BDA0003374998200000072
for the distance changes caused by the translation of the satellite,
Figure BDA0003374998200000073
is the distance change caused by the micro-motion of the satellite.
Further, after determining the distance of the scattering point relative to the radar, in one embodiment of the present application, the radar return data may be calculated by the following formula:
Figure BDA0003374998200000074
wherein σl(t) the echo amplitude modulation coefficient of the scattering point, c the propagation velocity of the electromagnetic wave, rlAnd (t) is the distance from the scattering point to the radar. Further, the phase function and the doppler shift function of the echo signal can be expressed as:
Figure BDA0003374998200000075
Figure BDA0003374998200000081
wherein the first term fBlukIs the Doppler shift caused by translation, the second term fmIs the micro doppler shift caused by rotation.
In order to more clearly illustrate a specific implementation manner of the present application for acquiring radar echo data of satellite micro-motion, the following detailed description is made for four exemplary satellite micro-motions respectively.
As a first example, the satellite rotation complex vibration will be described.
In which a satellite working normally in orbit requires to maintain a three-axis attitude stability to ensure that the transmitting and receiving antennas remain oriented to the ground and the solar panels remain oriented to the sun. A satellite that is malfunctioning or out of service will typically lose its attitude control capability, resulting in gross rotation and small amplitude vibrations.
In this example, the motion model of the satellite global rotation superimposed oscillation established by the present application is shown in fig. 5, where the centroid O of the satellite moves to the O "point and the target scatter point P 'moves to the P'" point over time t. For analysis, the motion process of point P is decomposed into translation at speed to point P' and then angular speed
Figure BDA0003374998200000082
Rotating from the point P 'to the point P' and finally vibrating from the point P 'to the point P'.
In one embodiment of the application, the radar echo data are calculated under a motion model of the satellite integral rotation compound vibration, and the method comprises the following steps: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite in a radar coordinate system, and an instantaneous rotation angular speed, a vibration frequency, a vibration amplitude and a vibration direction of the satellite in a target specimen 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 of 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 a 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 from any scattering point to the radar according to the fourth position coordinate; and calculating radar echo data of the overall 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 f0Observation duration T, sampling frequency fs。
Secondly, setting the initial attitude angle of the satellite in a radar coordinate system as
Figure BDA0003374998200000083
(phi is roll angle, theta is pitch angle, psi is yaw angle), initial distance
Figure BDA0003374998200000084
And translational velocity
Figure BDA0003374998200000085
Instantaneous rotation angular velocity under satellite body coordinate system
Figure BDA0003374998200000086
Vibration frequency f, vibration amplitude A and vibration direction
Figure BDA0003374998200000087
Third step, the time t, the rotation angle of the scattering point
Figure BDA0003374998200000088
The rotation matrix is obtained as follows:
Figure BDA0003374998200000091
fourthly, calculating the position coordinates of scattering points at the t moment after the movement
Figure BDA0003374998200000092
Fifthly, calculating the vibration distance at the time t
Figure BDA0003374998200000093
Sixthly, updating the position coordinates of the scattering points at the current observation time
Figure BDA0003374998200000094
Wherein the operation rule is as follows:
Figure BDA0003374998200000095
seventhly, according to the initial attitude angle of the satellite
Figure BDA0003374998200000096
Converting the satellite position coordinates into a reference coordinate system (X, Y, Z), the new position coordinates
Figure BDA0003374998200000097
Wherein
Figure BDA0003374998200000098
Eighthly, according to the position L' of the current scattering point and the initial distance of the satellite
Figure BDA0003374998200000099
And satellite translation velocity
Figure BDA00033749982000000910
Converting the position coordinates of the satellite into a radar coordinate system (U, V, W), wherein the new position coordinates of the ith e {1, 2, …, N } scattering points are
Figure BDA00033749982000000911
The ninth step, calculating the distance r from the first scattering point to the radarl(t)＝||L″′(l，：)||。
And tenth, calculating the radar echo s (t) of the simulation satellite model under the integral rotation compound vibration according to the formula for calculating the radar echo data.
As a second example, the description is made with the solar panel rotated along the long axis.
In order to obtain enough electric energy, when the satellite runs in an orbit, the solar sailboard slowly rotates according to the self posture so as to ensure that the sun is always oriented.
In this example, the motion model of the satellite solar panel rotating along the long axis established by the present application is shown in FIG. 6, where the centroid O of the target moves to the O 'point and the scattering point P of the target moves to the P' point over time t. For the convenience of analysis, the motion process of the P point is decomposed into the velocity
Figure BDA00033749982000000912
Translated to point P' and then at angular velocity
Figure BDA00033749982000000913
From point P' to point P ".
In one embodiment of the present application, calculating radar echo data under a motion model of a solar panel rotating along a long axis comprises the following steps: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite in a radar coordinate system; dividing all scattering points into solar sailboard scattering points and satellite component scattering points except the solar sailboard; calculating first part radar echo data of the solar sailboard rotating along the long axis based on the scattering points of the solar sailboard; calculating second part of radar echo data of the solar sailboard rotating along the long axis based on scattering points of satellite components except the solar sailboard; and adding the first part of radar echo data of the solar sailboard rotating along the long axis and the second part of radar echo data of the solar sailboard rotating along the long axis to obtain the radar echo data of the solar sailboard rotating along the long axis.
Specifically, in the first step, radar basic parameters are set: center frequency f0Observation duration T, sampling frequency fs。
Secondly, setting the initial attitude angle of the satellite in a radar coordinate system as
Figure BDA0003374998200000101
(phi is roll angle, theta is pitch angle, psi is yaw angle), initial distance
Figure BDA0003374998200000102
And translational velocity
Figure BDA0003374998200000103
And thirdly, dividing the satellite scattering points into solar panel scattering points and other satellite component scattering points, wherein the first part comprises translation and rotation, and the second part only comprises translation.
A fourth step of calculating the first part of the echo data s by referring to the calculation manner of the third step, the fourth step, and the seventh step to the tenth step in the first example1(t) of (d). Specifically, the time t is first elapsed, and the rotation angle of the scattering point
Figure BDA0003374998200000104
The rotation matrix is obtained as follows:
Figure BDA0003374998200000105
then calculating the position coordinates of the first part scattering points at the time t after the movement is carried out
Figure BDA0003374998200000106
Then according to the initial attitude angle of the satellite
Figure BDA0003374998200000107
Converting the satellite position coordinates into a reference coordinate system (X, Y, Z), the new position coordinates of any of the first partial scatter points being calculated by:
Figure BDA0003374998200000108
wherein the content of the first and second substances,
Figure BDA0003374998200000109
then according to the current scattering point position L' and the satellite initial distance
Figure BDA00033749982000001010
And satellite translation velocity
Figure BDA00033749982000001011
Converting the satellite position coordinates into a radar coordinate system (U, V, W), and calculating the new position coordinates of any scattering point in the first part of scattering points by the following formula:
Figure BDA00033749982000001012
and calculating the distance between the scattering point and the radar by the following formula: r isl(t) | | L' (L,: | | | L |, and finally, calculating the first part of echo data s of the solar panel rotating along the long axis according to a formula for calculating radar echo data1(t)。
A fifth step of calculating the second part of the echo data s by referring to the calculation manner of the seventh step to the tenth step in the first example2(t) of (d). Specifically, according to the initial attitude angle of the satellite
Figure BDA0003374998200000111
Converting the satellite position coordinates into a reference coordinate system (X, Y, Z), and calculating the new position coordinates of any scattering point in the second part of scattering points by the following formula:
Figure BDA0003374998200000112
wherein the content of the first and second substances,
Figure BDA0003374998200000113
then according to the current scattering point position L' and the satellite initial distance
Figure BDA0003374998200000114
And satellite translation velocity
Figure BDA0003374998200000115
Converting the satellite position coordinates into a radar coordinate system (U, V, W), any of the second partial scattering pointsA new position coordinate of a scattering point is
Figure BDA0003374998200000116
And calculates the distance r from the scattering point to the radarl(t) | | L' (L,: | | | L |, and finally, calculating the second part echo data s of the solar panel rotating along the long axis according to a formula for calculating radar echo data2(t)。
Sixthly, superposing the two echo signals to obtain a radar echo s (t) s of the simulation satellite solar panel rotating along the long axis1(t)+s2(t)。
As a third example, the solar panel is unfolded for explanation.
In this example, to study the radar echo of the satellite solar panel expansion, a solar panel expansion motion model of 3 connected components as shown in fig. 7 is established assuming that the satellite has two solar panels installed symmetrically on the left and right, and each solar panel is composed of 3 identical sub-panels. Wherein the centroid O of the target moves to point O 'and the scattering point P of the target moves to point P' over time t. For the convenience of analysis, the motion process of the P point is decomposed into the velocity
Figure BDA0003374998200000117
The translation to point P 'and then rotation from point P' to point P "at the flare angular velocity ω. In this example, radar echoes of satellite solar sailboard unfolding are simulated, and the long axis of the solar sailboard is set as the y axis in the satellite body coordinate system, so that the unfolding angular rate of the solar sailboard is ω.
In one embodiment of the present application, calculating radar return data under a motion model of solar panel deployment includes the steps of: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite in a radar coordinate system; dividing all scattering points into solar sailboard scattering points and satellite component scattering points except the solar sailboard; calculating a fifth position coordinate of a scattering point of the solar sailboard at the current moment according to the length of the sub-sailboard and the unfolding angle of the solar sailboard at the current moment; calculating first part of radar echo data of the unfolded solar sailboard based on the fifth position coordinates of the scattering points of the solar sailboard; calculating a second part of radar echo data of the unfolding of the solar sailboard based on a sixth position coordinate of a scattering point of the satellite component except the solar sailboard; and adding the first part of radar echo data of the unfolded solar sailboard and the second part of radar echo data of the unfolded solar sailboard to obtain the radar echo data of the unfolded solar sailboard.
Specifically, in the first step, radar basic parameters are set: center frequency f0Observation duration T, sampling frequency fs。
Secondly, setting the initial attitude angle of the satellite in a radar coordinate system as
Figure BDA0003374998200000121
(phi is roll angle, theta is pitch angle, psi is yaw angle), initial distance
Figure BDA0003374998200000122
And translational velocity
Figure BDA0003374998200000123
Thirdly, dividing the satellite scattering points into solar panel scattering points and other satellite component scattering points, 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 in the body coordinate system are respectively as follows:
Figure BDA0003374998200000124
fourthly, under a satellite body coordinate system, a kinematic model of the solar panel shown in fig. 8 is established, the model can show the positions of all points of the solar panel, and after the unfolding motion of time t, the coordinates of the joint 1 are constant to (x)1，y1，z1) Angle of spread of solar sailboard
Figure BDA0003374998200000125
The coordinates of the joint 2 are determined byThe following equation determines:
(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 panel. It should be noted that in the embodiment of the present application, a plurality of scattering points may be included at each joint, and only the x-axis position coordinates of different scattering points are different, the y-axis position coordinates and the z-axis position coordinates are the same, and the movement manner is also 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 C needs to be changed into the length C' from the current scattering point to the previous joint point. Therefore, the position coordinate L of the scattering point of the solar panel at the time t can be obtained according to the solar panel motion model and the coordinate calculation formula of the joint 2 and the joint 31′。
A fifth step of calculating the first part echo data s by referring to the calculation methods of the seventh step to the tenth step in the first example described above with respect to the first part scattering points, i.e., the solar panel scattering points1(t) of (d). Specifically, according to the initial attitude angle of the satellite
Figure BDA0003374998200000126
Converting the satellite position coordinates into a reference coordinate system (X, Y, Z), and calculating the new position coordinates of any scattering point in the solar panel scattering points according to the following formula:
Figure BDA0003374998200000131
wherein the content of the first and second substances,
Figure BDA0003374998200000132
then according to the current scattering point position L' and the satellite initial distance
Figure BDA0003374998200000133
And satellite translation velocity
Figure BDA0003374998200000134
Converting the satellite position coordinates into a radar coordinate system (U, V, W), and calculating the new position coordinates of any scattering point in the first part of scattering points by the following formula:
Figure BDA0003374998200000135
and calculating the distance between the scattering point and the radar by the following formula: r isl(t) | | L' (L,: | | | L |, and finally, the first part of echo data s under the solar panel expansion is calculated according to a formula for calculating radar echo data1(t)。
Sixthly, calculating the second part of the echo data s by referring to the calculation modes of the seventh step to the tenth step in the first example2(t) of (d). Specifically, according to the initial attitude angle of the satellite
Figure BDA0003374998200000136
Converting the satellite position coordinates into a reference coordinate system (X, Y, Z), and calculating the new position coordinates of any scattering point of the scattering points of the rest satellite components according to the following formula:
Figure BDA0003374998200000137
wherein the content of the first and second substances,
Figure BDA0003374998200000138
it should be noted that the new position coordinate of any one of the scattering points of the other satellite components, that is, the sixth position coordinate, is the position coordinate of the other satellite components after the solar panel is unfolded for t time, and the new position coordinate may be calculated specifically according to the motion, for example, the translation or rotation, performed by the other satellite components in the practical application, and the specific calculation mode may refer to the above-mentioned phaseThe calculation of coordinates in motion is not described herein.
Further, according to the current scattering point position L' and the satellite initial distance
Figure BDA0003374998200000139
And satellite translation velocity
Figure BDA00033749982000001310
Converting the satellite position coordinates into a radar coordinate system (U, V, W), and calculating the new position coordinates of any scattering point in the second part of scattering points by the following formula:
Figure BDA00033749982000001311
and calculating the distance between the scattering point and the radar by the following formula: r isl(t) | | L' (L,: | | L |, and finally, calculating the second part echo data s of the solar panel under expansion according to a formula for calculating radar echo data2(t)。
Seventhly, superposing the two parts of radar echoes to obtain a radar echo s (t) s expanded by the simulation satellite solar panel1(t)+s2(t)。
As a fourth example, the explanation is made with the antenna deployment complex rotation.
In order to ensure effective transmission of signals, the satellite antenna needs to be aligned to a target direction during operation. The satellite antenna is initially set to a retracted state, the antenna is deployed along the bottom connection point over time, and the antenna face rotates towards the target direction.
In this example, the motion model for the antenna unfolding complex rotation established by the present application is shown in FIG. 9, where the centroid O of the target moves to the O 'point and the scattering point P of the target moves to the P' point over time t. For the convenience of analysis, the motion process of the P point is decomposed into the velocity
Figure BDA0003374998200000141
Translated to point P' and then expanded at angular velocity
Figure BDA0003374998200000142
Moving from point P 'to point P' and finally at an angular velocity
Figure BDA0003374998200000143
From point P "to point P'". In this example, the radar echo of a satellite antenna unfolding composite rotation is simulated.
In one embodiment of the present application, the method for calculating radar echo data under the motion model of antenna unfolding composite rotation comprises the following steps: setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite in a radar coordinate system, and a satellite antenna deployment angular speed, a bottom connection point coordinate and an antenna rotation angular speed of the satellite in a target specimen coordinate system; dividing all scattering points into antenna scattering points and satellite component scattering points except the antenna; calculating a seventh position coordinate of an antenna scattering point at the current moment according to the satellite antenna unfolding angular velocity, the bottom connection point coordinate and the antenna rotation angular velocity; calculating first part radar echo data of antenna unfolding composite rotation based on seventh position coordinates of scattering points of the antenna; calculating a second part of radar echo data of the antenna expansion composite rotation based on eighth position coordinates of scattering points of the satellite components 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 panel unfolding.
Specifically, in the first step, radar basic parameters are set: center frequency f0Observation duration T, sampling frequency fs。
Secondly, setting the initial attitude angle of the satellite in a radar coordinate system as
Figure BDA0003374998200000144
(phi is roll angle, theta is pitch angle, psi is yaw angle), initial distance
Figure BDA0003374998200000145
And translational velocity
Figure BDA0003374998200000146
Bottom connection point coordinates
Figure BDA0003374998200000147
Thirdly, dividing the scattering points of the satellite into two parts, namely 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 comprises translational motion, and the position coordinates of the first part of the scattering points and the second part of the scattering points under the body coordinate system are respectively as follows:
Figure BDA0003374998200000148
fourthly, in this example, the antenna performs the unfolding composite rotation, so that after the movement time t, the position coordinate of any scattering point in the first part of the current observation time is calculated by the following formula:
Figure BDA0003374998200000151
a fifth step of calculating the first part of the echo data s by referring to the calculation methods of the seventh step to the tenth step in the first example1(t) of (d). Specifically, according to the initial attitude angle of the satellite
Figure BDA0003374998200000152
Converting the satellite position coordinates into a reference coordinate system (X, Y, Z), and calculating the new position coordinates of any scattering point of the antenna scattering points according to the following formula:
Figure BDA0003374998200000153
wherein the content of the first and second substances,
Figure BDA0003374998200000154
then according to the current scattering point position L' and the satellite initial distance
Figure BDA0003374998200000155
And satellite translation velocity
Figure BDA0003374998200000156
Converting the satellite position coordinates into a radar coordinate system (U, V, W), and calculating the new position coordinates of any scattering point in the first part of scattering points by the following formula:
Figure BDA0003374998200000157
and calculating the distance between the scattering point and the radar by the following formula: r isl(t) | | L' (L,: | | L |, and finally, the first part of echo data s under the antenna unfolding composite rotation is calculated according to a formula for calculating radar echo data1(t)。
Sixthly, calculating the second part of the echo data s by referring to the calculation modes of the seventh step to the tenth step in the first example, the second part of the scattering points, namely the scattering points of the other satellite components except the antenna2(t) of (d). Specifically, according to the initial attitude angle of the satellite
Figure BDA0003374998200000158
Converting the satellite position coordinates into a reference coordinate system (X, Y, Z), and calculating the new position coordinates of any scattering point in the scattering points of the rest satellite components except the antenna by the following formula:
Figure BDA0003374998200000159
wherein the content of the first and second substances,
Figure BDA00033749982000001510
it should be noted that the new position coordinate of any scattering point of the scattering points of the other satellite components except the antenna, i.e. the eighth position coordinate, is the composite rotation of the antenna deploymentAfter the movement is performed for t time, the position coordinates of the other satellite components may be specifically calculated according to the movement, for example, the rotation, performed by the other satellite components in the actual application, and the specific calculation mode may refer to the coordinate calculation mode in the rotation, which is not described herein again.
Further, according to the current scattering point position L' and the satellite initial distance
Figure BDA00033749982000001511
And satellite translation velocity
Figure BDA00033749982000001512
Converting the satellite position coordinates into a radar coordinate system (U, V, W), and calculating the new position coordinates of any scattering point in the second part of scattering points by the following formula:
Figure BDA0003374998200000161
and calculating the distance between the scattering point and the radar by the following formula: r isl(t) | | L' (L,: | | L |, and finally, calculating the second part echo data s under the antenna unfolding composite rotation according to a formula for calculating the radar echo data2(t)。
Seventhly, superposing the two parts of radar echoes to obtain a radar echo s (t) s of the antenna unfolding composite rotation1(t)+s2(t)。
Therefore, modeling analysis is carried out on the four typical micro motions of the artificial satellite, and radar echo data under each motion filling is obtained.
And 103, performing time-frequency analysis on the radar echo data of each satellite micromotion to obtain a time-frequency spectrogram of each satellite micromotion.
Specifically, the 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 an embodiment of the present application, a time-frequency analysis may be performed through a short-time fourier transform, and in specific implementation, the time-frequency analysis may be performed on radar echo data of each satellite micro-motion through the following formula:
Ts(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 in different micro motion states, is favorable for further deep 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 scattering points of the satellite is established based on the preset number of scattering points, then a plurality of micro-motions of the satellite to be simulated are determined, a motion model is established for each micro-motion of the satellite, radar echo data of the current micro-motion of the satellite is calculated under each motion model, and finally time-frequency analysis is performed on the radar echo data of each micro-motion of the satellite to obtain a time-frequency spectrogram of each micro-motion of the satellite. Therefore, the method can simulate the micro Doppler effect caused by the micro motion of the satellite, displays time-frequency spectrograms in different micro motion states, solves the technical problem that the deep study of the micro motion of the space target is limited due to the fact that a radar special for micro motion monitoring perception of the space target is lacked in the related technology and the accumulated data volume of radar echo is insufficient, researches the micro motion state of the satellite through a simulation technology, can obtain the fine characteristics of the satellite through 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 more clearly illustrate the specific implementation process of the radar signal simulation method for the satellite micro-motion state according to the embodiment of the present application, a specific embodiment is described below, and the specific embodiment includes the following three steps:
step one, establishing a satellite scattering point three-dimensional simulation model.
The prototype of the satellite constructed by simulation in the application is shown in fig. 2, wherein the satellite is 32m long, 4m wide and 8m high (the solar panel and the antenna are unfolded). The three-dimensional scattering point model was built in MATLAB software based on satellite shape and size, as shown in fig. 3. The simulation satellite sets 125 scattering points, namely N is 125, and the initial position matrix is
Figure BDA0003374998200000171
It should be noted that scattering points of key components such as the satellite main body, the solar panel and the antenna are individually grouped so as to generate radar echoes caused by micro-motion of the key components in the next step.
And step two, modeling the satellite micro-motion.
This example designs 4 typical satellite micromotions: the method comprises the steps of firstly, compounding rotation and vibration of the whole satellite, secondly, rotating the solar sailboard along a long shaft, thirdly, unfolding the solar sailboard and fourthly, compounding and rotating the antenna unfolding, and can also expand other micro-motion simulation according to the method.
The method comprises the following steps of:
1) setting basic parameters of the radar: center frequency f014GHz, observation duration T100 s, sampling frequency fs＝200Hz；
2) Setting an initial attitude angle of a satellite in a radar coordinate system
Figure BDA0003374998200000172
Initial distance
Figure BDA0003374998200000173
And translational velocity
Figure BDA0003374998200000174
Instantaneous rotation angular velocity under satellite body coordinate system
Figure BDA0003374998200000175
Vibration frequency f is 0.01Hz, vibration amplitude A is 1m, vibration direction
Figure BDA0003374998200000176
3) Over time t, angle of rotation of scattering point
Figure BDA0003374998200000177
Obtaining a rotation matrix:
Figure BDA0003374998200000178
4) scattering point position coordinates at time t
Figure BDA0003374998200000179
5) Vibrating distance at time t;
Figure BDA00033749982000001710
6) updating the position coordinates of scattering points at the current observation time
Figure BDA0003374998200000181
7) According to the initial attitude angle of the satellite
Figure BDA0003374998200000182
Converting the satellite position coordinates into a reference coordinate system (X, Y, Z), the new position coordinates
Figure BDA0003374998200000183
Wherein the content of the first and second substances,
Figure BDA0003374998200000184
8) according to the current scattering point position L' and the initial distance of the satellite
Figure BDA0003374998200000185
And satellite translation velocity
Figure BDA0003374998200000186
And converting the satellite position coordinates into a radar coordinate system (U, V, W), wherein the new position coordinates of the ith e {1, 2, …, 125} scattering point are as follows:
L″′(l，：)＝L″(l，：)+[800000，350000，250000]+[10t，5t，0]
9) calculating the distance r from the ith scattering point to the radarl(t)＝||L″′(l，：)||；
10) And obtaining the radar echo s (t) of the simulation satellite integral rotation compound vibration according to the radar echo data calculation formula.
Secondly, the solar sailboard rotates along the long axis, and the method comprises the following steps:
1) setting basic parameters of the radar: center frequency f014GHz, observation duration T100 s, sampling frequency fs＝200Hz；
2) Setting an initial attitude angle of a satellite in a radar coordinate system
Figure BDA0003374998200000187
Initial distance
Figure BDA0003374998200000188
And translational velocity
Figure BDA0003374998200000189
Rotation angular velocity of solar sailboard in satellite body coordinate system
Figure BDA00033749982000001810
3) Dividing the satellite scattering points into two parts, namely solar panel scattering points and other satellite components, wherein the first part comprises translation and rotation, and the second part only comprises translation;
4) the first part of scattering points are referred to in step 3), step 4) and steps 7) to 10) of the first part of echo data s1(t)；
5) Second partial scattering point referencing (7) to (10) in the first embodiment) generates second partial echo data s2(t)；
6) Two part echoThe signal superposition is carried out to obtain the radar echo s (t) s of the simulation satellite solar panel rotating along the long axis1(t)+s2(t)。
Thirdly, unfolding the solar sailboard, comprising the following steps:
1) setting basic parameters of the radar: center frequency f014GHz, observation duration T100 s, sampling frequency fs＝200Hz；
2) Setting an initial attitude angle of a satellite in a radar coordinate system
Figure BDA0003374998200000191
Initial distance
Figure BDA0003374998200000192
And translational velocity
Figure BDA0003374998200000193
Solar array spread angle rate under satellite body coordinate system
Figure BDA0003374998200000194
3) Dividing the satellite scattering points into two parts, namely solar panel scattering points and other satellite components, wherein the first part comprises translation and unfolding motion, the second part only has translation, and the position coordinates of the second part under a body coordinate system are respectively as follows:
Figure BDA0003374998200000195
4) in the satellite body coordinate system, the kinematic model of the solar panel is shown in fig. 8, and the sub-panel length C is 4 m. The coordinate of the joint 1 is constant as (x)1,y1,z1) Is identical to (0,4,0), and the unfolding angle of the solar panel is determined according to the current time
Figure BDA0003374998200000196
The joint 2 and joint 3 coordinates are:
Figure BDA0003374998200000197
Figure BDA0003374998200000198
wherein, each joint can contain a plurality of scattering points, the position coordinates of only the x axis of different scattering points are different, the position coordinates of the y axis and the z axis are the same, and the movement mode is also the same. Without loss of generality, 1 scattering point is taken as an example at each joint. For scattering points on the solar sailboard except for the joint point, calculation can be carried out according to the coordinate calculation formula of the joint 2 and the joint 3, and the length of the sub-sailboard is only changed into the length C' from the front scattering point to the front joint. Thereby obtaining the position coordinate L of the scattering point of the solar panel at the time t1′。
5) According to the position coordinates L of the scattering point of the solar panel1' refer to step 7) to step 10) in (1) generating first partial echo data s1(t)；
6) Position coordinates L of second part scattering point2' refer to step 7) to step 10) in (1) to generate second partial echo data s2(t)；
7) Superposing the two parts of radar echoes to obtain the radar echo s (t) s of the simulated satellite solar sailboard1(t)+s2(t)。
And fourthly, for the antenna unfolding composite rotary motion, the method comprises the following calculation steps:
1) setting basic parameters of the radar: center frequency f014GHz, observation duration T100 s, sampling frequency fs＝200Hz；
2)2) setting an initial attitude angle of the satellite in a radar coordinate system
Figure BDA0003374998200000201
Initial distance
Figure BDA0003374998200000202
And translational velocity
Figure BDA0003374998200000203
Satellite antenna expansion angular velocity under satellite body coordinate system
Figure BDA0003374998200000204
Bottom connection point coordinates
Figure BDA0003374998200000205
Angular velocity of antenna rotation
Figure BDA0003374998200000206
3) Dividing the satellite scattering points into two parts, namely antenna scattering points and other satellite component scattering points, wherein the first part comprises translation and unfolding composite rotation, the second part only has translation, and the position coordinates of the second part under a body coordinate system are respectively as follows:
Figure BDA0003374998200000207
4) considering the unfolding composite rotation, the position coordinates of the scattering points of the first part at the current observation time are
Figure BDA0003374998200000208
5) First partial scattering Point L1' refer to step 7) to step 10) in (1) to generate first partial echo data s1(t)；
6) Second partial scattering Point L2Refer to step 7) to step 10) in (1) to generate second partial echo data s2(t)；
7) Superposing the two parts of radar echoes to obtain the radar echo s (t) s of the simulation satellite antenna which is unfolded and rotated in a composite way1(t)+s2(t)。
And step three, performing time-frequency analysis on the radar echoes in the four micromotion states to obtain a time-frequency spectrogram corresponding to each micromotion.
Specifically, the time-frequency analysis is sequentially performed on the acquired four types of radar echo data of the micro motion, so as to sequentially obtain a time-frequency spectrogram of the satellite integral rotation composite vibration shown in fig. 10, a time-frequency spectrogram of the satellite solar panel shown in fig. 11 rotating along the long axis, a time-frequency spectrogram of the satellite solar panel shown in fig. 12, and a time-frequency spectrogram of the satellite antenna expansion composite rotation shown in fig. 13.
The abscissa of the several Time-frequency spectrograms is Time (Time) in seconds, and the ordinate is Doppler (Doppler) in hertz.
In order to implement the foregoing embodiments, the present application further provides a radar signal simulation apparatus for a satellite in a micro-motion state, and fig. 14 is a schematic structural diagram of the radar signal simulation apparatus for a satellite in a micro-motion state according to the embodiments of the present application.
As shown in fig. 14, the apparatus includes a creation module 100, a calculation module 200, and an analysis module 300.
The building module 100 is configured to build a three-dimensional simulation model of satellite scattering points based on a preset number of scattering points, where each preset component in the three-dimensional simulation model of satellite scattering points has a corresponding scattering point group.
The calculation module 200 is configured to determine a plurality of satellite micro motions to be simulated, establish a radar coordinate system, a target specimen 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 the 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 integral rotation compound vibration, the solar array rotation along the long axis, the solar array expansion and the antenna expansion compound rotation.
And the analysis module 300 is configured to perform time-frequency analysis on the radar echo data of each satellite micromotion, and obtain a time-frequency spectrogram of each satellite micromotion.
Optionally, in an 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 in a radar coordinate system, and an instantaneous rotation angular speed, a vibration frequency, a vibration amplitude and a vibration direction of the satellite in a target specimen 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 of 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 a 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 from any scattering point to the radar according to the fourth position coordinate; and calculating radar echo data of the overall 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 embodiment of the method for simulating a radar signal in an artificial satellite micro-motion state is also applicable to the device for simulating a radar signal in an artificial satellite micro-motion state of the present embodiment, and the implementation principle is similar, and is not described herein again.
To sum up, the radar signal simulation device to artificial satellite micro-motion state of this application embodiment, can simulate the micro-Doppler effect that the satellite micro-motion arouses, and show the time frequency spectrogram under the different micro-motion state, it lacks the radar that is exclusively used in space target micro-motion monitoring perception to have solved among the correlation technique, the radar echo data volume of accumulation is not enough, lead to having restricted the technical problem of the micro-motion deep study to the space target, through the micro-motion state of simulation technology research satellite, can obtain the meticulous characteristic of satellite with lower cost research, for designing more efficient satellite monitoring system provides theoretical support, be favorable to more accurate and efficient monitoring satellite's micro-motion.
In order to achieve the above embodiments, the present invention further proposes a non-transitory computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements the method for simulating a radar signal for a satellite micro-motion state according to the embodiment of the first aspect of the present application.
In the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," 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 application. In this specification, the schematic representations of the terms used above are not necessarily intended to 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. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited 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 steps of a custom logic function or process, and alternate 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, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present application.
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). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the 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 application 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. 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.
It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.
In addition, functional units in the embodiments of the present application may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.
The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc. Although embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application, and that variations, modifications, substitutions and alterations may be made to the above embodiments by those of ordinary skill in the art within the scope of the present application.

Claims (10)

1. A radar signal simulation method aiming at a micro-motion state of an artificial satellite is characterized by comprising the following steps:
establishing a satellite scattering point three-dimensional simulation model based on a preset number of scattering points, wherein each preset component in the satellite scattering point three-dimensional simulation model has a corresponding scattering point group;
determining a plurality of satellite micro motions to be simulated, establishing a radar coordinate system, a target specimen coordinate system and a reference coordinate system, respectively establishing motion models 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 method comprises the following steps of satellite integral rotation composite vibration, solar sailboard rotation along a long axis, solar sailboard unfolding and antenna unfolding composite rotation;
and performing time-frequency analysis on the radar echo data of each satellite micromotion to obtain a time-frequency spectrogram of each satellite micromotion.
2. The method of claim 1, wherein calculating radar echo data under a motion model of the satellite global rotation compound vibration comprises:
setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite in a radar coordinate system, and an instantaneous rotation angular speed, a vibration frequency, a vibration amplitude and a vibration direction of the satellite in a target specimen 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 of 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 to obtain 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 from any scattering point to a 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.
3. The method of claim 2, wherein calculating radar return data under the motion model of the solar windsurfing board rotating along the long axis comprises:
setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite in a radar coordinate system;
dividing all scattering points into solar sailboard scattering points and satellite component scattering points except the solar sailboard;
calculating first part radar echo data of the solar sailboard rotating along the long axis based on the scattering points of the solar sailboard;
calculating a second part of radar echo data of the solar sailboard rotating along the long axis based on the scattering points of the satellite components except the solar sailboard;
and adding the first part of radar echo data of the solar sailboard rotating along the long axis and the second part of radar echo data of the solar sailboard rotating along the long axis to obtain the radar echo data of the solar sailboard rotating along the long axis.
4. The method of claim 2, wherein calculating radar return data under the motion model of the solar windsurfing board deployment comprises:
setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite in a radar coordinate system;
dividing all scattering points into solar sailboard scattering points and satellite component scattering points except the solar sailboard;
calculating a fifth position coordinate of a scattering point of the solar sailboard at the current moment according to the length of the sub-sailboard and the unfolding angle of the solar sailboard at the current moment;
calculating first part of radar echo data of the unfolding of the solar sailboard based on the fifth position coordinates of the scattering points of the solar sailboard;
calculating a second portion of radar echo data of the solar sailboard deployment based on the sixth position coordinates of the scattering points of the satellite components other than the solar sailboard;
and adding the first part of radar echo data of the unfolded solar sailboard and the second part of radar echo data of the unfolded solar sailboard to obtain the radar echo data of the unfolded solar sailboard.
5. The method of claim 2, wherein computing radar echo data under a motion model of the antenna deployment complex rotation comprises:
setting radar basic parameters, and setting an initial attitude angle, an initial distance and a translational speed of a satellite in a radar coordinate system, and a satellite antenna deployment angular speed, a bottom connection point coordinate and an antenna rotation angular speed of the satellite in a target specimen coordinate system;
dividing all scattering points into antenna scattering points and satellite component scattering points except the antennas;
calculating a seventh position coordinate of an antenna scattering point at the current moment according to the satellite antenna unfolding angular velocity, the bottom connection point coordinate and the antenna rotation angular velocity;
calculating first part radar echo data of antenna unfolding composite rotation based on seventh position coordinates of the scattering points of the antenna;
calculating a second part of radar echo data of antenna expansion composite rotation based on the eighth position coordinate of the scattering point of the satellite component 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 sailboard unfolding.
6. The method of claim 1, wherein the time-frequency analysis is performed on the radar echo data of each of the satellite micromotions by the following formula:
Ts(t，w)＝∫s(τ)w(τ-t)e-jωτdτ
where w (t) is a window function and s (t) is radar echo data.
7. The method of any of claims 1-5, wherein the radar echo data is calculated by the formula:
Figure FDA0003374998190000031
wherein σl(t) the echo amplitude modulation coefficient of the scattering point, c the propagation velocity of the electromagnetic wave, r1And (t) is the distance from the scattering point to the radar.
8. A radar signal simulation device for a satellite micro-motion state is characterized by comprising:
the satellite scattering point three-dimensional simulation system comprises an establishing module, a calculating module and a calculating module, wherein the establishing module is used for establishing a satellite scattering point three-dimensional simulation model based on a preset number of scattering points, and each preset component in the satellite scattering point three-dimensional simulation model has a corresponding scattering point group;
the calculation module is used for determining a plurality of satellite micro motions to be simulated, establishing a radar coordinate system, a target specimen 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 method comprises the following steps of satellite integral rotation composite vibration, solar sailboard rotation along a long axis, solar sailboard unfolding and antenna unfolding composite rotation;
and the analysis module is used for performing time-frequency analysis on the radar echo data of each satellite micromotion to obtain a time-frequency spectrogram of each satellite micromotion.
9. The apparatus of claim 8, wherein 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 in a radar coordinate system, and an instantaneous rotation angular speed, a vibration frequency, a vibration amplitude and a vibration direction of the satellite in a target specimen 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 of 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 to obtain 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 from any scattering point to a 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.
10. A non-transitory computer readable storage medium having stored thereon a computer program, wherein the computer program, when executed by a processor, implements a method for radar signal simulation for satellite micro-motion states as claimed in any one of claims 1-7.
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