CN116679302A - Method and system for designing large-breadth mode of satellite-borne SAR based on load and attitude coordination - Google Patents

Method and system for designing large-breadth mode of satellite-borne SAR based on load and attitude coordination Download PDF

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CN116679302A
CN116679302A CN202310512581.6A CN202310512581A CN116679302A CN 116679302 A CN116679302 A CN 116679302A CN 202310512581 A CN202310512581 A CN 202310512581A CN 116679302 A CN116679302 A CN 116679302A
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satellite
angle
load
imaging
scanning
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范军
王赟
王海涛
徐锡杰
侯雨生
姜岩
韦锡峰
于迎军
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Shanghai Institute of Satellite Engineering
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Shanghai Institute of Satellite Engineering
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/9094—Theoretical aspects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T3/00—Geometric image transformation in the plane of the image
    • G06T3/40—Scaling the whole image or part thereof
    • G06T3/4038—Scaling the whole image or part thereof for image mosaicing, i.e. plane images composed of plane sub-images

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  • Remote Sensing (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Electromagnetism (AREA)
  • Theoretical Computer Science (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

The application provides a method and a system for designing a large-breadth mode of a satellite-borne SAR based on load and attitude matching, wherein the method comprises the following implementation steps: calculating a satellite side swing angle; the satellite moves to a side swing angle around the Xb axis of the body system; calculating a load electric scanning compensation angle and a satellite attitude pitch angle; the satellite moves around the Yb axis to the pitch angle to keep a forward strabismus imaging state; the load is rapidly switched to the radio wave beam through SAR antenna distance to realize forward squint ScanSAR imaging; repeating the steps to sequentially finish the forward-looking side-looking and backward-looking ScanSAR imaging. The application realizes SAR large-width imaging by utilizing the integrated imaging design of the load large-angle electric scanning capability and the satellite platform attitude rapid maneuvering capability. Meanwhile, the antenna is designed into a one-dimensional electric scanning mode, so that the antenna structure is greatly simplified, the weight and cost of the whole satellite are reduced, and the use requirements of a user on the lightweight and low-cost SAR satellite are met.

Description

Method and system for designing large-breadth mode of satellite-borne SAR based on load and attitude coordination
Technical Field
The application relates to the technical field of aerospace systems, in particular to a method and a system for designing a large-breadth mode of a satellite-borne SAR based on load and attitude coordination.
Background
The spaceborne synthetic aperture radar is an all-weather active earth observation means in all days, and plays an important role in the fields of high-resolution observation, natural resource monitoring, ocean monitoring and the like. With the development of application requirements of the spaceborne SAR, low-cost and lightweight SAR satellites have become development hot spots of the spaceborne SAR system. In the aspect of the requirement of a satellite-borne SAR satellite, the load large-breadth imaging mode has important significance for meeting the accurate observation requirement of large area and wide coverage. The SAR satellite adopting the parabolic antenna system realizes the weight reduction and low cost of the satellite, but cannot realize the large-breadth imaging of the load due to the limited electric wave beam scanning capability; the SAR satellite adopting the two-dimensional plane phased array antenna system can realize the load large-breadth imaging through a distance to an electric wave beam ScanSAR scanning mode, but the ScanSAR scanning mode often reduces the azimuth resolution at the cost of wide observation band width. Meanwhile, the two-dimensional plane phased array antenna system SAR satellite needs a large number of T/R components in the two-dimensional direction of the antenna, and the T/R components greatly increase the weight, the power consumption, the cost and the engineering development difficulty of the whole satellite.
Through searching, although a plurality of patents and papers exist in China on the research of a large-breadth mode method of a satellite-borne SAR, the method is essentially different from the method in design, and the specific conditions are as follows:
the method uses a parabolic antenna to save the manufacturing cost of the spaceborne SAR antenna, but has smaller range imaging width due to the limitation of the electric scanning capability of the parabolic antenna.
The research institute Feng Fan of space radio technology in western ampere and the like invents an on-orbit implementation design method of a parabolic satellite-borne SAR mosaic mode, and patent application No. 202010752732.1 provides a mosaic mode design method aiming at an SAR satellite of a parabolic antenna system.
The foreign terra SAR-X satellite scanning mode is realized by adopting a traditional ScanSAR mode (article name: terra SAR-X Image Product Guide), wherein the resolution is designed to be 16m, and the range-wise breadth is designed to be 100km. If the resolution is kept unchanged according to the design method of the application, the range width can reach 300km; the narrow scanning mode and the wide scanning mode of the high-resolution third satellite in China are realized by adopting a traditional ScanSAR mode (the article name is that the high-resolution third satellite is designed to be 50m and the range-wise breadth is designed to be 300 km). If the resolution is kept unchanged according to the design method of the application, the range-wise width can reach 900km.
Therefore, a new solution is needed to improve the above technical problems.
Disclosure of Invention
Aiming at the defects in the prior art, the application aims to provide a method and a system for designing a large-breadth mode of a satellite-borne SAR based on load and attitude matching.
According to the application, the method for designing the large-breadth mode of the satellite-borne SAR based on the coordination of the load and the gesture comprises the following steps:
step S1: calculating a satellite side swing angle; the satellite moves around the Xb axis of the body system to the side swing angle of the platform under the two-dimensional guiding posture;
step S2: calculating an electric scanning compensation angle and an attitude pitch angle according to the satellite side-sway angle, the lower view angle and the azimuth-to-bias view angle; the satellite platform drives SAR antenna electric wave beams to complete forward-looking angular scanning of azimuth through attitude maneuver around Yb axis of the system, so that the satellite keeps a forward-looking imaging state;
step S3: in the imaging time range, the load is rapidly switched to the electric wave beam through the SAR antenna distance to finish the front squint ScanSAR imaging;
step S4: and repeating the steps S1-S3, and sequentially completing the forward-side view and backward-squint ScanSAR imaging by the load within the imaging time range.
Preferably, in the step S1, the selection of the yaw angle of the satellite is related to the satellite task, and when the satellite uses multi-target observation as the main task, the yaw angle is set to 0 °, and the satellite maintains the flat flight mode and switches to the electric wave beam through the SAR antenna distance; if the satellite takes high-resolution imaging as a main task, the side swing angle of the platform can be calculated according to the size of a lower viewing angle, the satellite moves to a fixed angle around an Xb axis of the system, and beam scanning is completed by matching with SAR antenna electric wave beams; when the roll angle is set to be a positive value, the satellite keeps a left side view working mode; when the roll angle is set to be a negative value, the satellite keeps a right side view working mode; when the roll angle is set to zero, the satellite remains in the flat fly mode of operation.
Preferably, in the step S2, the SAR imaging is completed by matching the satellite attitude and the load, and before each imaging, a distance is provided for the load to scan the compensation angle θbl1 for the electric wave beam, and an attitude pitch angle θb1 is provided for the satellite platform; θbL1 and θb1 are calculated based on the satellite yaw angle φcs1, the downview angle θL1, and the azimuthal squint angle θ1 parameters byAnd theta bL ＝arsin[sin(θ L -φ cs )·cosθ]And calculating the coordinate conversion relation.
Preferably, in the step S3, a one-dimensional planar phased array system SAR antenna is used to scan a distance-wise large-angle radio beam.
Preferably, the step S4 includes the steps of:
step S4.1: the satellite moves around the Xb axis of the body system to a second platform side swing angle phi cs2 under a two-dimensional guiding posture;
step S4.2: calculating an electric scanning compensation angle thetabl 2 and a posture pitch angle thetab 2 according to a satellite side swing angle phi cs2, a lower view angle thetal 2 and an azimuth squint angle thetal 2, wherein the load finishes the lower view angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front squint to front squint by maneuvering around the Yb axis of the system;
step S4.3: in the second imaging time range, the load is rapidly switched to the electric wave beam through the distance to finish the scanning imaging of the front-side view ScanSAR strip;
step S4.4: the satellite moves around the Xb axis of the system to a third platform side swing angle phi cs3 under the two-dimensional guiding posture;
step S4.5: calculating an electric scanning compensation angle thetabl 3 and a posture pitch angle thetab 3 according to a satellite side swinging angle phi cs3, a lower viewing angle thetal 3 and an azimuth squint angle thetal 3, wherein the load finishes the lower viewing angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front side view to rear squint view of the azimuth squint angle through posture maneuver around the Yb axis of the system;
step S4.6: and in the third imaging time range, the load is subjected to squint ScanSAR strip scanning imaging after the switching of the load to the electric wave beam is completed through distance.
The application also provides a satellite-borne SAR large-breadth mode design system based on load and attitude matching, which comprises the following modules:
module M1: calculating a satellite side swing angle; the satellite moves around the Xb axis of the body system to the side swing angle of the platform under the two-dimensional guiding posture;
module M2: calculating an electric scanning compensation angle and an attitude pitch angle according to the satellite side-sway angle, the lower view angle and the azimuth-to-bias view angle; the satellite platform drives SAR antenna electric wave beams to complete forward-looking angular scanning of azimuth through attitude maneuver around Yb axis of the system, so that the satellite keeps a forward-looking imaging state;
module M3: in the imaging time range, the load is rapidly switched to the electric wave beam through the SAR antenna distance to finish the front squint ScanSAR imaging;
module M4: and repeatedly triggering the modules M1-M3 to execute work, and sequentially completing the forward-looking side-looking and backward-looking ScanSAR imaging by the load in the imaging time range.
Preferably, in the module M1, the satellite yaw angle is selected in association with a satellite mission, and when the satellite uses multi-target observation as a main mission, the yaw angle is set to 0 °, and the satellite maintains a flat flight mode and switches to the electric wave beam through the SAR antenna distance; if the satellite takes high-resolution imaging as a main task, the side swing angle of the platform can be calculated according to the size of a lower viewing angle, the satellite moves to a fixed angle around an Xb axis of the system, and beam scanning is completed by matching with SAR antenna electric wave beams; when the roll angle is set to be a positive value, the satellite keeps a left side view working mode; when the roll angle is set to be a negative value, the satellite keeps a right side view working mode; when the roll angle is set to zero, the satellite remains in the flat fly mode of operation.
Preferably, in the module M2, SAR imaging is completed by matching satellite attitude and load, and before each imaging, a distance is provided for the load to scan the compensation angle θbl1 for the electric wave beam, and an attitude pitch angle θb1 is provided for the satellite platform; θbL1 and θb1 are calculated based on the satellite yaw angle φcs1, the downview angle θL1, and the azimuthal squint angle θ1 parameters byAnd theta bL ＝arsin[sin(θ L -φ cs )·cosθ]And calculating the coordinate conversion relation.
Preferably, in the module M3, a one-dimensional planar phased array system SAR antenna is used for scanning a distance-wise large-angle radio beam.
Preferably, the module M4 comprises the following modules:
module M4.1: the satellite moves around the Xb axis of the body system to a second platform side swing angle phi cs2 under a two-dimensional guiding posture;
module M4.2: calculating an electric scanning compensation angle thetabl 2 and a posture pitch angle thetab 2 according to a satellite side swing angle phi cs2, a lower view angle thetal 2 and an azimuth squint angle thetal 2, wherein the load finishes the lower view angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front squint to front squint by maneuvering around the Yb axis of the system;
module M4.3: in the second imaging time range, the load is rapidly switched to the electric wave beam through the distance to finish the scanning imaging of the front-side view ScanSAR strip;
module M4.4: the satellite moves around the Xb axis of the system to a third platform side swing angle phi cs3 under the two-dimensional guiding posture;
module M4.5: calculating an electric scanning compensation angle thetabl 3 and a posture pitch angle thetab 3 according to a satellite side swinging angle phi cs3, a lower viewing angle thetal 3 and an azimuth squint angle thetal 3, wherein the load finishes the lower viewing angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front side view to rear squint view of the azimuth squint angle through posture maneuver around the Yb axis of the system;
module M4.6: and in the third imaging time range, the load is subjected to squint ScanSAR strip scanning imaging after the switching of the load to the electric wave beam is completed through distance.
Compared with the prior art, the application has the following beneficial effects:
1. compared with the traditional ScanSAR mode, the method provided by the application adopts forward squint ScanSAR, front side squint ScanSAR and rear squint ScanSAR for scanning and splicing imaging in the distance direction, and the distance direction width can be increased by 3 times;
2. compared with a mode of fixing a platform side view angle adopted by an SAR satellite based on a two-dimensional plane phased array system antenna, the method provided by the application adopts a satellite platform maneuver to multi-gear side swing angle to cooperate with SAR antenna electric wave beam scanning design, and improves SAR imaging performance indexes such as sensitivity, distance ambiguity and the like of a high-view wave position system by reducing attenuation of antenna scanning gain;
3. compared with the SAR satellite with the current reflector antenna, the planar phased array antenna has the advantages of rapid, flexible and efficient electric wave beam switching function, and can improve the target observation efficiency;
4. according to the application, through adopting multi-angle scanning modes such as front strabismus, front side view, rear strabismus and the like of the satellite for imaging, the observation under a plurality of different angles can be carried out for a plurality of targets in one navigation, the scattering characteristics of the targets under different azimuth angles can be obtained, and the aim of enriching the observation information of the targets can be achieved while the observation efficiency of the targets is improved;
5. the method provided by the application can greatly simplify the antenna structure, reduce the weight, volume and cost of the whole satellite, and meet the use requirement of a user on the light and small SAR satellite.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
FIG. 1 is a schematic flow chart of the method of the present application;
FIG. 2 is a schematic diagram of the operation mode of the method of the present application;
FIG. 3 is a schematic diagram of the geometrical relationship between satellite attitude maneuver and load sweep angle in accordance with the method of the present application.
Detailed Description
The present application will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present application, but are not intended to limit the application in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present application.
Example 1:
according to the application, the method for designing the large-breadth mode of the spaceborne SAR based on the coordination of the load and the gesture comprises the following steps:
step S1: calculating a satellite side swing angle; the satellite moves around the Xb axis of the body system to the side swing angle of the platform under the two-dimensional guiding posture; the satellite side swing angle is selected to be related to a satellite task, when the satellite takes multi-target observation as a main task, the side swing angle is set to be 0 degrees, the satellite keeps a flat flight mode, and the satellite is switched to an electric wave beam through SAR antenna distance; if the satellite takes high-resolution imaging as a main task, the side swing angle of the platform can be calculated according to the size of a lower viewing angle, the satellite moves to a fixed angle around an Xb axis of the system, and beam scanning is completed by matching with SAR antenna electric wave beams; when the roll angle is set to be a positive value, the satellite keeps a left side view working mode; when the roll angle is set to be a negative value, the satellite keeps a right side view working mode; when the roll angle is set to zero, the satellite remains in the flat fly mode of operation.
Step S2: calculating an electric scanning compensation angle and an attitude pitch angle according to the satellite side-sway angle, the lower view angle and the azimuth-to-bias view angle; the satellite platform drives SAR antenna electric wave beams to complete forward-looking angular scanning of azimuth through attitude maneuver around Yb axis of the system, so that the satellite keeps a forward-looking imaging state; SAR imaging is completed by adopting satellite attitude and load matching, a distance is provided for the load to scan a compensation angle thetab 1 to an electric wave beam before each imaging, and an attitude pitch angle thetab 1 is provided for a satellite platform; θbL1 and θb1 are calculated based on the satellite yaw angle φcs1, the downview angle θL1, and the azimuthal squint angle θ1 parameters byAnd theta bL ＝arsin[sin(θ L -φ cs )·cosθ]And calculating the coordinate conversion relation.
Step S3: in the imaging time range, the load is rapidly switched to the electric wave beam through the SAR antenna distance to finish the front squint ScanSAR imaging; and scanning the distance-oriented large-angle radio beam by adopting a one-dimensional planar phased array system SAR antenna.
Step S4: repeating the steps S1-S3, and sequentially completing the forward-side view and backward-squint ScanSAR imaging by the load in the imaging time range;
step S4.1: the satellite moves around the Xb axis of the body system to a second platform side swing angle phi cs2 under a two-dimensional guiding posture;
step S4.2: calculating an electric scanning compensation angle thetabl 2 and a posture pitch angle thetab 2 according to a satellite side swing angle phi cs2, a lower view angle thetal 2 and an azimuth squint angle thetal 2, wherein the load finishes the lower view angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front squint to front squint by maneuvering around the Yb axis of the system;
step S4.3: in the second imaging time range, the load is rapidly switched to the electric wave beam through the distance to finish the scanning imaging of the front-side view ScanSAR strip;
step S4.4: the satellite moves around the Xb axis of the system to a third platform side swing angle phi cs3 under the two-dimensional guiding posture;
step S4.5: calculating an electric scanning compensation angle thetabl 3 and a posture pitch angle thetab 3 according to a satellite side swinging angle phi cs3, a lower viewing angle thetal 3 and an azimuth squint angle thetal 3, wherein the load finishes the lower viewing angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front side view to rear squint view of the azimuth squint angle through posture maneuver around the Yb axis of the system;
step S4.6: and in the third imaging time range, the load is subjected to squint ScanSAR strip scanning imaging after the switching of the load to the electric wave beam is completed through distance.
Example 2:
example 2 is a preferable example of example 1 to more specifically explain the present application.
The application also provides a satellite-borne SAR large-breadth mode design system based on load and attitude matching, which comprises the following modules:
module M1: calculating a satellite side swing angle; the satellite moves around the Xb axis of the body system to the side swing angle of the platform under the two-dimensional guiding posture; the satellite side swing angle is selected to be related to a satellite task, when the satellite takes multi-target observation as a main task, the side swing angle is set to be 0 degrees, the satellite keeps a flat flight mode, and the satellite is switched to an electric wave beam through SAR antenna distance; if the satellite takes high-resolution imaging as a main task, the side swing angle of the platform can be calculated according to the size of a lower viewing angle, the satellite moves to a fixed angle around an Xb axis of the system, and beam scanning is completed by matching with SAR antenna electric wave beams; when the roll angle is set to be a positive value, the satellite keeps a left side view working mode; when the roll angle is set to be a negative value, the satellite keeps a right side view working mode; when the roll angle is set to zero, the satellite remains in the flat fly mode of operation.
Module M2: calculating an electric scanning compensation angle and an attitude pitch angle according to the satellite side-sway angle, the lower view angle and the azimuth-to-bias view angle; the satellite platform drives SAR antenna electric wave beams to complete forward-looking angular scanning of azimuth through attitude maneuver around Yb axis of the system, so that the satellite keeps a forward-looking imaging state; using satellite attitude and load matchingSAR imaging is completed, a distance is provided for a load to scan a compensation angle thetabl 1 to an electric wave beam before each imaging, and a posture pitch angle thetabl 1 is provided for a satellite platform; θbL1 and θb1 are calculated based on the satellite yaw angle φcs1, the downview angle θL1, and the azimuthal squint angle θ1 parameters byAnd theta bL ＝arsin[sin(θ L -φ cs )·cosθ]And calculating the coordinate conversion relation.
Module M3: in the imaging time range, the load is rapidly switched to the electric wave beam through the SAR antenna distance to finish the front squint ScanSAR imaging; and scanning the distance-oriented large-angle radio beam by adopting a one-dimensional planar phased array system SAR antenna.
Module M4: repeatedly triggering the modules M1-M3 to execute work, and sequentially completing the forward-looking side-looking and backward-looking ScanSAR imaging by the load in the imaging time range;
module M4.1: the satellite moves around the Xb axis of the body system to a second platform side swing angle phi cs2 under a two-dimensional guiding posture;
module M4.2: calculating an electric scanning compensation angle thetabl 2 and a posture pitch angle thetab 2 according to a satellite side swing angle phi cs2, a lower view angle thetal 2 and an azimuth squint angle thetal 2, wherein the load finishes the lower view angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front squint to front squint by maneuvering around the Yb axis of the system;
module M4.3: in the second imaging time range, the load is rapidly switched to the electric wave beam through the distance to finish the scanning imaging of the front-side view ScanSAR strip;
module M4.4: the satellite moves around the Xb axis of the system to a third platform side swing angle phi cs3 under the two-dimensional guiding posture;
module M4.5: calculating an electric scanning compensation angle thetabl 3 and a posture pitch angle thetab 3 according to a satellite side swinging angle phi cs3, a lower viewing angle thetal 3 and an azimuth squint angle thetal 3, wherein the load finishes the lower viewing angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front side view to rear squint view of the azimuth squint angle through posture maneuver around the Yb axis of the system;
module M4.6: and in the third imaging time range, the load is subjected to squint ScanSAR strip scanning imaging after the switching of the load to the electric wave beam is completed through distance.
Example 3:
example 3 is a preferable example of example 1 to more specifically explain the present application.
In order to solve the problems in the prior art, the application designs a satellite-borne SAR large-breadth mode design method based on load and attitude coordination, and mainly realizes forward squint, forward side view and backward squint ScanSAR multi-scan stitching imaging in a mode of electric scanning of SAR antenna distance and attitude maneuver coordination of an azimuth satellite. Compared with the traditional ScanSAR mode, the mode of the application can be improved by 3 times aiming at the range width. Meanwhile, the target observation efficiency is ensured based on the rapid, flexible and efficient beam arbitrary pointing (target) rapid switching capability of the planar active phased array antenna. In addition, the planar phased array antenna is designed to scan in a one-dimensional distance to a large angle, so that the weight, the volume and the cost of the whole satellite are greatly reduced.
The embodiment provides a satellite-borne SAR large-breadth mode design method based on load and attitude matching, which comprises the following steps:
step 1: calculating a satellite side swing angle; the satellite moves around the Xb axis of the body system to the side swing angle of the platform under the two-dimensional guiding posture;
step 2: calculating an electric scanning compensation angle and an attitude pitch angle according to the satellite side-sway angle, the lower view angle and the azimuth-to-bias view angle; the satellite platform drives SAR antenna electric wave beams to complete forward-looking angular scanning of azimuth through attitude maneuver around Yb axis of the system, so that the satellite keeps a forward-looking imaging state;
step 3: in the imaging time range, the load is rapidly switched to the electric wave beam through the SAR antenna distance to finish the front squint ScanSAR imaging;
step 4: and (3) repeating the steps 1-3, and sequentially completing the forward-side view and backward-squint ScanSAR imaging by the load within the imaging time range.
Further, in the step 1, the selection of the side swing angle of the satellite is related to the satellite task, when the satellite uses multi-target observation as the main task, the side swing angle is set to be 0 °, the satellite keeps a flat flight mode, and the satellite is rapidly and flexibly switched to the electric wave beam through the SAR antenna distance, so that the target observation efficiency is improved; if the satellite takes high-resolution imaging as a main task, the platform side swing angle can be calculated according to the size of the lower visual angle, the satellite moves to a fixed angle around the Xb axis of the system, and beam scanning is completed by matching with SAR antenna electric wave beams, so that the load imaging performance can be improved. When the roll angle is set to be a positive value, the satellite keeps a left side view working mode; when the roll angle is set to be a negative value, the satellite keeps a right side view working mode; when the roll angle is set to zero, the satellite remains in the flat fly mode of operation. The satellite provided by the application adopts a plurality of single-frame control moment gyroscopes, so that the rapid maneuvering of the side-swinging angle of the satellite can be realized, and the working mode of the satellite can be flexibly switched according to the requirements of users.
Further, in the step 2, the application completes the SAR imaging by adopting the coordination of the satellite attitude and the load, and before each imaging, in order to ensure that the satellite attitude maneuver drives the SAR antenna electric wave beam to point to the center of the scene, a distance-direction electric wave beam scanning compensation angle θbl1 is required to be provided for the load, and an attitude pitch angle θb1 is provided for the satellite platform; θbL1 and θb1 are determined by the satellite yaw angle φcs1, the downview angle θL1, the azimuthal squint angle θ1, and other parametersAnd theta bL ＝arsin[sin(θ L -φ cs )·cosθ]And calculating the coordinate conversion relation.
In step 3, a one-dimensional planar phased array system SAR antenna is used to realize scanning of the electric wave beam in a range direction with a large angle, so that imaging in a range direction with a large breadth is ensured. Meanwhile, the antenna is designed to be one-dimensional scanning, so that the weight and cost of the whole satellite are greatly reduced.
Step 4.1: 1) The satellite moves around the Xb axis of the body system to a second platform side swing angle phi cs2 under a two-dimensional guiding posture; 2) Calculating an electric scanning compensation angle thetabl 2 and a posture pitch angle thetab 2 according to a satellite side swing angle phi cs2, a lower view angle thetal 2 and an azimuth squint angle thetal 2, wherein the load finishes the lower view angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front squint to front squint by maneuvering around the Yb axis of the system; 3) In the second imaging time range, the load is rapidly switched to the electric wave beam through the distance to finish the scanning imaging of the front-side view ScanSAR strip;
step 4.2: 1) The satellite moves around the Xb axis of the system to a third platform side swing angle phi cs3 under the two-dimensional guiding posture; 2) Calculating an electric scanning compensation angle thetabl 3 and a posture pitch angle thetab 3 according to a satellite side swinging angle phi cs3, a lower viewing angle thetal 3 and an azimuth squint angle thetal 3, wherein the load finishes the lower viewing angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front side view to rear squint view of the azimuth squint angle through posture maneuver around the Yb axis of the system; 3) In the third imaging time range, the load is subjected to strabismus ScanSAR strip scanning imaging after the rapid switching of the load to the electric wave beam is completed through distance;
further, in the step 4, the load is electrically scanned to the wave beam through the SAR antenna distance in a given imaging time range to realize the rapid switching of a plurality of adjacent wave positions, and the coordination of the attitude maneuver of the satellite platform, so as to sequentially complete the scanning imaging of the front-side view and rear-squint ScanSAR strips. Wherein the second imaging start time Ts2 and end time Te2 should satisfy a relationship of ts2=te1+td, te2=ts2+s/Vg, and the third imaging start time Ts3 and end time Te3 should satisfy a relationship of ts3=te2+td, te3=ts3+s/Vg, where Td represents the satellite attitude maneuver time between two images.
In addition, in order to ensure that the satellite completes attitude maneuver before the next imaging, the maneuver time Td should be satisfied
Relationship (where Re is earth radius, R is satellite front side bearing oblique, θ is azimuth angle, S is azimuth imaging length, vg is satellite ground speed, ls is synthetic aperture length). According to the application, the satellite platform adopts a plurality of single-frame control moment gyro bodies, so that the satellite can be rapidly maneuvered in posture, and the normal imaging requirement of a load is met.
Fig. 1 shows the specific implementation steps of the present application:
(1) Satellite front squint ScanSAR stripe scan imaging:
calculating a satellite side swing angle; the satellite moves around an Xb axis of the system under a two-dimensional guiding posture to a first platform side swing angle; calculating an electric scanning compensation angle and an attitude pitch angle according to the satellite side-sway angle, the lower view angle and the azimuth-to-bias view angle; the satellite platform drives SAR antenna electric wave beams to finish forward direction squint angle scanning through attitude maneuver around Yb axis of the system; and the load is rapidly switched to the electric wave beam through SAR antenna distance to finish forward squint ScanSAR strip scanning imaging.
(2) Satellite front-side scan sar stripe scan imaging:
calculating a satellite side swing angle; the satellite moves around the Xb axis of the body system to the side swing angle of the second platform under the two-dimensional guiding posture; calculating an electric scanning compensation angle and an attitude pitch angle according to the satellite side-sway angle, the lower view angle and the azimuth-to-bias view angle; the satellite platform drives SAR antenna electric wave beams to finish scanning from front squint to front side view in azimuth squint angle through attitude maneuver around Yb axis of the system; and the load is rapidly switched to the electric wave beam through the SAR antenna distance to finish the scanning imaging of the front-side view ScanSAR strip.
(3) Satellite rear squint ScanSAR stripe scan imaging:
calculating a satellite side swing angle; the satellite moves around the Xb axis of the body system to the side swing angle of the third platform under the two-dimensional guiding posture; calculating an electric scanning compensation angle and an attitude pitch angle according to the satellite side-sway angle, the lower view angle and the azimuth-to-bias view angle; the satellite platform drives SAR antenna electric wave beams to finish scanning from front side view to rear squint in azimuth squint angle through attitude maneuver around Yb axis of the system; and (3) performing squint ScanSAR strip scanning imaging after the load is rapidly switched to the electric wave beam through SAR antenna distance.
Referring to fig. 2, fig. 2 is a schematic diagram of a working mode of a method for designing a large-breadth mode of a satellite-borne SAR based on load and attitude matching according to an embodiment of the present application.
In the embodiment of the application, fig. 3 is a schematic diagram of a geometrical relationship between a satellite attitude maneuver and a load electric scan angle provided for an embodiment of the application, wherein the figure is a right side view flight state, O-XbYbZb is a satellite body system, θl is a satellite lower view angle, θ is an azimuth angle, θb is an attitude pitch angle, and θcs is a satellite platform side swing angle, and θbl is an electric scan compensation angle.
The effects of the present application will be further described with reference to simulation data.
The space-borne SAR orbit is selected to have the height of about 500km, the X frequency band, the central viewing angle of 12.92-24.97 degrees, the antenna is designed to be a planar active phased array system with one-dimensional large-angle scanning, the azimuth oblique viewing angle of + -30 degrees, the resolution of 8m and the azimuth observation band length of 120km; the distance direction is designed as ScanSAR 3 hops, the distance width of each Burst is designed to be 17km, the adjacent wave positions overlap by 1-2km, the imaging bandwidth of the adjacent three wave positions is designed to be 45km, and the distance direction total observation bandwidth is designed to be 135km.
According to the above-mentioned input system demand parameters, according to the method design provided by the application, a group of wave position simulation parameters are output, as shown in the following table:
table 1 output parameters in examples
The satellites were first forward-looking ScanSAR imaged: firstly, inputting wave position parameter information, including a lower viewing angle, a side swing angle and an azimuth oblique viewing angle; calculating relevant parameters according to the method provided by the application; under the two-dimensional guiding posture, the satellite moves around the Xb axis of the system to a left side view by 10 degrees, and then moves around the Yb axis of the system to a pitch angle by 30.03 degrees to keep a front strabismus imaging state; within a given imaging time, the load scans the electric wave beam by-2.53 degrees, -3.92 degrees and-5.29 degrees in sequence through SAR antenna distance to complete forward squint ScanSAR strip scanning imaging.
The satellite performs a second positive side view ScanSAR imaging: firstly, inputting wave position parameter information, including a lower viewing angle, a side swing angle and an azimuth oblique viewing angle; calculating relevant parameters according to the method provided by the application; under the two-dimensional guiding posture, the satellite moves around the Xb axis of the system to a left side view of 20 degrees, and then moves around the Yb axis of the system to a pitch angle of 0 degrees to keep a front side view imaging state; in a given imaging time, the load sequentially scans the electric wave beam by 2.33 degrees, 0.81 degrees and-0.69 degrees through the SAR antenna distance to finish the scanning imaging of the front-side view ScanSAR strip.
The satellite performs a third post squint ScanSAR imaging: firstly, inputting wave position parameter information, including a lower viewing angle, a side swing angle and an azimuth oblique viewing angle; calculating relevant parameters according to the method provided by the application; under the two-dimensional guiding posture, the satellite moves around the Xb axis of the system to a left side view of 20 degrees, and then moves around the Yb axis of the system to a pitch angle of-30.02 degrees to keep a rear squint imaging state; within a given imaging time, the load is scanned to the electric wave beam through SAR antenna distance by-1.86 degrees, -3.10 degrees, -4.30 degrees in sequence, and then squint ScanSAR strip scanning imaging is completed.
The present embodiment will be understood by those skilled in the art as more specific descriptions of embodiment 1 and embodiment 2.
Those skilled in the art will appreciate that the application provides a system and its individual devices, modules, units, etc. that can be implemented entirely by logic programming of method steps, in addition to being implemented as pure computer readable program code, in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. Therefore, the system and various devices, modules and units thereof provided by the application can be regarded as a hardware component, and the devices, modules and units for realizing various functions included in the system can also be regarded as structures in the hardware component; means, modules, and units for implementing the various functions may also be considered as either software modules for implementing the methods or structures within hardware components.
The foregoing describes specific embodiments of the present application. It is to be understood that the application is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the application. The embodiments of the application and the features of the embodiments may be combined with each other arbitrarily without conflict.

Claims (10)

1. A method for designing a large-breadth mode of a satellite-borne SAR based on load and attitude matching is characterized by comprising the following steps:
step S1: calculating a satellite side swing angle; the satellite moves around the Xb axis of the body system to the side swing angle of the platform under the two-dimensional guiding posture;
step S2: calculating an electric scanning compensation angle and an attitude pitch angle according to the satellite side-sway angle, the lower view angle and the azimuth-to-bias view angle; the satellite platform drives SAR antenna electric wave beams to complete forward-looking angular scanning of azimuth through attitude maneuver around Yb axis of the system, so that the satellite keeps a forward-looking imaging state;
step S3: in the imaging time range, the load is rapidly switched to the electric wave beam through the SAR antenna distance to finish the front squint ScanSAR imaging;
step S4: and repeating the steps S1-S3, and sequentially completing the forward-side view and backward-squint ScanSAR imaging by the load within the imaging time range.
2. The method for designing a large-breadth mode of a satellite-borne SAR based on load and attitude matching according to claim 1, wherein in the step S1, the selection of the side swing angle of the satellite is related to the task of the satellite, when the satellite takes multi-target observation as a main task, the side swing angle is set to 0 DEG, the satellite keeps a flat flight mode, and the satellite is switched to an electric wave beam through SAR antenna distance; if the satellite takes high-resolution imaging as a main task, the side swing angle of the platform can be calculated according to the size of a lower viewing angle, the satellite moves to a fixed angle around an Xb axis of the system, and beam scanning is completed by matching with SAR antenna electric wave beams; when the roll angle is set to be a positive value, the satellite keeps a left side view working mode; when the roll angle is set to be a negative value, the satellite keeps a right side view working mode; when the roll angle is set to zero, the satellite remains in the flat fly mode of operation.
3. The method for designing a large-breadth mode of a satellite-borne SAR based on load and attitude matching according to claim 1, wherein in the step S2, SAR imaging is completed by adopting satellite attitude and load matching, and before each imaging, a distance is provided for the load to scan a compensation angle θbL1 to an electric wave beam, and an attitude pitch angle θb1 is provided for a satellite platform; θbL1 and θb1 are calculated based on the satellite yaw angle φcs1, the downview angle θL1, and the azimuthal squint angle θ1 parameters byAndand calculating the coordinate conversion relation.
4. The method for designing the large-breadth mode of the space-borne SAR based on the matching of the load and the gesture as set forth in claim 1, wherein in the step S3, a one-dimensional planar phased array system SAR antenna is adopted to scan the distance-wise large-angle radio beam.
5. The method for designing a large-breadth mode of a satellite-borne SAR based on load and attitude matching according to claim 1, wherein said step S4 comprises the steps of:
step S4.1: the satellite moves around the Xb axis of the body system to a second platform side swing angle phi cs2 under a two-dimensional guiding posture;
step S4.2: calculating an electric scanning compensation angle thetabl 2 and a posture pitch angle thetab 2 according to a satellite side swing angle phi cs2, a lower view angle thetal 2 and an azimuth squint angle thetal 2, wherein the load finishes the lower view angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front squint to front squint by maneuvering around the Yb axis of the system;
step S4.3: in the second imaging time range, the load is rapidly switched to the electric wave beam through the distance to finish the scanning imaging of the front-side view ScanSAR strip;
step S4.4: the satellite moves around the Xb axis of the system to a third platform side swing angle phi cs3 under the two-dimensional guiding posture;
step S4.5: calculating an electric scanning compensation angle thetabl 3 and a posture pitch angle thetab 3 according to a satellite side swinging angle phi cs3, a lower viewing angle thetal 3 and an azimuth squint angle thetal 3, wherein the load finishes the lower viewing angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front side view to rear squint view of the azimuth squint angle through posture maneuver around the Yb axis of the system;
step S4.6: and in the third imaging time range, the load is subjected to squint ScanSAR strip scanning imaging after the switching of the load to the electric wave beam is completed through distance.
6. A spaceborne SAR large-breadth mode design system based on load and attitude matching is characterized by comprising the following modules:
module M1: calculating a satellite side swing angle; the satellite moves around the Xb axis of the body system to the side swing angle of the platform under the two-dimensional guiding posture;
module M2: calculating an electric scanning compensation angle and an attitude pitch angle according to the satellite side-sway angle, the lower view angle and the azimuth-to-bias view angle; the satellite platform drives SAR antenna electric wave beams to complete forward-looking angular scanning of azimuth through attitude maneuver around Yb axis of the system, so that the satellite keeps a forward-looking imaging state;
module M3: in the imaging time range, the load is rapidly switched to the electric wave beam through the SAR antenna distance to finish the front squint ScanSAR imaging;
module M4: and repeatedly triggering the modules M1-M3 to execute work, and sequentially completing the forward-looking side-looking and backward-looking ScanSAR imaging by the load in the imaging time range.
7. The system according to claim 6, wherein in the module M1, the satellite yaw angle is selected in association with a satellite mission, and when the satellite uses multi-objective observation as a main mission, the yaw angle is set to 0 °, the satellite keeps a flat flight mode, and the satellite switches to an electric wave beam through the SAR antenna distance; if the satellite takes high-resolution imaging as a main task, the side swing angle of the platform can be calculated according to the size of a lower viewing angle, the satellite moves to a fixed angle around an Xb axis of the system, and beam scanning is completed by matching with SAR antenna electric wave beams; when the roll angle is set to be a positive value, the satellite keeps a left side view working mode; when the roll angle is set to be a negative value, the satellite keeps a right side view working mode; when the roll angle is set to zero, the satellite remains in the flat fly mode of operation.
8. The load and attitude matching-based spaceborne SAR wide mode design system according to claim 6, wherein in said module M2, SAR imaging is accomplished using satellite attitude and load matching, and before each imaging, a distance is provided to the load to scan the compensating angle θbl1 for the beam, and an attitude pitch angle θb1 is provided to the satellite platform; θbL1 and θb1 are calculated based on the satellite yaw angle φcs1, the downview angle θL1, and the azimuthal squint angle θ1 parameters byAndand calculating the coordinate conversion relation.
9. The load and attitude matching-based spaceborne SAR large breadth mode design system according to claim 6, wherein in said module M3, a one-dimensional planar phased array system SAR antenna is used for distance-wise large-angle beam scanning.
10. The load and attitude coordination based spaceborne SAR wide mode design system of claim 6, wherein said module M4 comprises the following modules:
module M4.1: the satellite moves around the Xb axis of the body system to a second platform side swing angle phi cs2 under a two-dimensional guiding posture;
module M4.2: calculating an electric scanning compensation angle thetabl 2 and a posture pitch angle thetab 2 according to a satellite side swing angle phi cs2, a lower view angle thetal 2 and an azimuth squint angle thetal 2, wherein the load finishes the lower view angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front squint to front squint by maneuvering around the Yb axis of the system;
module M4.3: in the second imaging time range, the load is rapidly switched to the electric wave beam through the distance to finish the scanning imaging of the front-side view ScanSAR strip;
module M4.4: the satellite moves around the Xb axis of the system to a third platform side swing angle phi cs3 under the two-dimensional guiding posture;
module M4.5: calculating an electric scanning compensation angle thetabl 3 and a posture pitch angle thetab 3 according to a satellite side swinging angle phi cs3, a lower viewing angle thetal 3 and an azimuth squint angle thetal 3, wherein the load finishes the lower viewing angle scanning to an electric wave beam through SAR antenna distance, and the satellite platform drives the SAR antenna electric wave beam to finish the scanning from front side view to rear squint view of the azimuth squint angle through posture maneuver around the Yb axis of the system;
module M4.6: and in the third imaging time range, the load is subjected to squint ScanSAR strip scanning imaging after the switching of the load to the electric wave beam is completed through distance.
CN202310512581.6A 2023-05-08 2023-05-08 Method and system for designing large-breadth mode of satellite-borne SAR based on load and attitude coordination Pending CN116679302A (en)

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