Agile platform and radar load collaborative satellite-borne SAR irregular multi-target observation method

Abstract

The invention provides a satellite-borne SAR irregular multi-target observation method based on agile platform and radar load cooperation. The method comprises the steps of 1, selecting multiple targets distributed in an irregular region according to user requirements and satellite characteristics, and performing task planning; 2, satellite agile platform control design; 3, designing a satellite working mode; 4, designing a load antenna scanning mode; 5, designing a multi-target observation mode; and step 6, designing a multi-target on-satellite real-time processing mode. According to the method, multi-beam-position and multi-parameter real-time calculation and autonomous planning design are autonomously carried out on a satellite for multiple targets distributed irregularly, and continuous and efficient observation of multiple targets in one imaging task can be realized by combining the rapid, flexible and efficient electric beam switching capability of the load phased-array antenna.

Description

Technical Field

[0001] The present invention belongs to the technical field of aerospace systems, and in particular, relates to a spaceborne SAR irregular multi-target observation method in which an agile platform and a radar payload are coordinated. Background Art

[0002] Spaceborne synthetic aperture radar is an active earth observation method that can identify, confirm, search and discover important land and sea targets. In practical applications, the distribution of multiple targets often does not match the direction of satellite tracks, and the distribution of targets is irregular. For example, coastlines, borders and railway lines.

[0003] The coastline is the baseline of the marine development strategy, which represents the boundary between land and sea. In order to protect the coastline ecology, it is urgent to monitor the coastline construction activities and their dynamic changes quickly and accurately. If a wide coverage method is used, it is difficult to obtain high-resolution ground feature details; if multiple high-resolution observation modes are used, multiple satellite imaging will seriously reduce the effectiveness of multi-target observation.

[0004] After searching, it is found that there are many invention patents in China related to the present invention in the research of irregular multi-target observation method of spaceborne SAR, but they are essentially different from the present invention in the implementation of the method, as follows:

[0005] The patent document "SAR satellite observation method and system for non-along-track target areas" (2022, patent application number 202210043049.X) uses the two-dimensional electronic scanning capability of the SAR satellite planar active phased array to achieve mosaic stitching mode imaging of non-along-track targets. The patent document designs the SAR satellite phased array antenna as a two-dimensional electronic scan, which increases the number of T / R component channels in the two-dimensional direction of the payload antenna. These T / R components greatly increase the weight, volume, cost, and engineering development difficulty of the entire satellite. In addition, the mosaic mode proposed in the patent document is an emerging mode, and the current space-borne SAR series satellites have no development experience in this mode;

[0006] The patent document “A method and device for processing coastline position change information” (2021, patent application number 202110327014.4) proposes a method for detecting coastline changes using satellite remote sensing images. The patent document does not mention the irregular multi-target observation method of spaceborne SAR;

[0007] The patent document “A simulation method and process for synthetic aperture radar echo signals under non-linear track conditions” (2016, patent application number 201610708438.4) proposes a SAR echo signal simulation method for non-linear track imaging mode. The patent document does not mention the irregular multi-target observation method of spaceborne SAR.

[0008] Patent document “A Spaceborne Non-along-track SAR Multi-mode Integrated Frequency Domain Imaging Method” (2022, Patent Application No. 202210379408.9), which proposes a non-along-track SAR multi-mode integrated frequency domain imaging method. The patent document does not mention a spaceborne SAR irregular multi-target observation method;

[0009] The paper "A Method for Off-track Strip Division of Agile Satellites for Regional Targets" (2016, Science, Technology and Engineering) proposed a method for strip division of multiple continuous imaging targets for agile satellites. This method uses the three-axis satellite attitude maneuver to continuously switch beams for multiple target areas. Compared with the beam electronic scanning method of the planar phased array antenna of the spaceborne SAR, the observation efficiency is significantly reduced.

[0010] The paper "A New Mode of Non-tracking Imaging for Spaceborne SAR: Opportunities and Challenges" (2022, Journal of Radars) proposes a new idea for the new mode of non-tracking imaging for spaceborne SAR, and puts forward higher requirements and challenges for onboard mission planning, satellite agile platform, and payload antenna design capabilities. This method is still in the demonstration stage and has not been actually verified in orbit.

[0011] The patent document “Target group observation based on SAR satellite, target group observation method and device” (2024, patent application number 202311280334.4) provides a target group observation method based on SAR satellite, a target group observation method and device, including obtaining the first key information of the target group to be observed and the second key information of the SAR satellite determined for the target group to be observed, generating an attitude adjustment scheme of the SAR satellite based on the maximum azimuth oblique angle of the SAR satellite determined by the first key information and the second key information, and generating an observation plan of the SAR satellite relative to the target group to be observed based on the attitude adjustment scheme, so that when the SAR satellite executes the observation plan, the SAR satellite can continuously control the regular changes of the attitude of the SAR satellite according to the attitude adjustment scheme, so that the antenna field of view can cover the designated target area for a longer time, thereby improving the SAR satellite's single-pass intensive observation capability for the target group in the area. However, the patent document does not mention the irregular multi-target observation method of spaceborne SAR. Summary of the invention

[0012] In view of the defects in the prior art, the object of the present invention is to provide a spaceborne SAR irregular multi-target observation method in which an agile platform and a radar payload are coordinated.

[0013] According to the present invention, a spaceborne SAR irregular multi-target observation method in which an agile platform and a radar payload are coordinated includes:

[0014] Step S100: performing satellite mission planning and imaging parameter setting according to the multi-target distribution law in the irregular area selected by the user;

[0015] Step S200: Continuous imaging of multiple targets is achieved by continuously changing the parameters of the satellite payload once it is powered on.

[0016] Preferably, the step S100 includes:

[0017] Step S101: Calculate the downward viewing angle θL of each target according to the number of satellite orbit elements, determine the imaging width W, and obtain the matching satellite platform side swing angle;

[0018] Step S102: Calculate the intervals between adjacent target points based on the target over-the-top moment, determine the single mission duration of each target based on the maximum satellite power-on time and the number of multiple targets, and finally select the observation band length of a single target; determine the total number of satellite imaging times and the total mission duration.

[0019] Preferably, the step S200 includes:

[0020] Step S201: For continuous irregular multiple targets, after determining the task start time of each target imaging window and the first target, the satellite platform side swing angle is sent to the attitude and orbit control subsystem T1 seconds in advance, so that the satellite platform attitude changes from the sun-facing state to the ground-facing level flight state; the data transmission integrated package is sent to the onboard data processor T2 seconds in advance, and after the onboard processor receives the instruction, it ensures that each stand-alone module is powered on on time; the target point information package is sent to the payload system T3 seconds in advance;

[0021] Step S202: During this multi-target observation and imaging mission, for targets that are discovered and set as important, the current imaging mission will not be terminated, and imaging parameter calculation and planning processing will be carried out in parallel; if the multi-target field of view size in the next area is within the payload antenna beam scanning range, no attitude control is required, and after the current mission is completed, the payload software will autonomously calculate the radar parameters of the mission in advance; if the multi-target field of view size exceeds the payload antenna beam scanning capability, after the current imaging is completed, the imaging attitude control of the new target will be switched.

[0022] Preferably, in the process of changing the attitude of the satellite platform from the state of flying toward the sun to the state of flying toward the ground, the attitude and orbit control adopts three-axis zero-momentum attitude control, and when the payload is working, the attitude is determined by combining the star sensor and the fiber optic gyroscope, and the flywheel is driven by the feedforward combined with the closed-loop feedback attitude control to realize the three-axis attitude control and maneuvering of the satellite working toward the ground.

[0023] Preferably, the payload phased array antenna adopts one-dimensional large-angle scanning in the range direction, and through the satellite yaw maneuver of ±90 degrees, the antenna range direction and azimuth direction are interchanged to obtain the antenna azimuth direction The ability to scan forward and backward obliquely through a large-angle beam.

[0024] Preferably, in step S200:

[0025] In order to address the deviation of multi-target aiming accuracy caused by orbital altitude changes, the satellite can automatically correct the power-on time. The actual satellite imaging power-on time is calculated based on real-time orbit information, target point location information, and mission duration information.

[0026] For irregular multi-target templates, the control payload system adopts a continuous observation mode with autonomous switching of multiple wave positions. For one-time imaging, the control payload system autonomously calculates the multi-wave position radar parameters in advance based on the target point group sent by the satellite, and autonomously selects the matching observation wave position. Among them, the payload system software adopts a millisecond-level wave position switching rate and millisecond-level beam switching of the payload phased array antenna.

[0027] Preferably, in step S200:

[0028] The control payload system sets the target number in the echo auxiliary data received on board according to the target observation order for analysis by the on-board real-time processing module and ground data processing.

[0029] Preferably, it also includes:

[0030] Step S300: Data cutting is performed according to the target number of the SAR echo data; the relevant area data is extracted according to the designated longitude and latitude information of each target, and imaging processing is completed on the satellite; key target detection and positioning processing is performed on the imaging results, and the processed target slices are transmitted to the data transmission subsystem.

[0031] According to the present invention, a spaceborne SAR irregular multi-target observation system based on the coordination of an agile platform and a radar payload is provided, comprising:

[0032] Module M100: Satellite mission planning and imaging parameter setting based on the distribution pattern of multiple targets in irregular areas selected by the user;

[0033] Module M200: Continuous imaging of multiple targets is achieved by controlling the satellite to start up once and continuously change the payload parameters.

[0034] A satellite provided by the present invention uses the satellite-borne SAR irregular multi-target observation method in which the agile platform and the radar payload are coordinated to perform observation.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The present invention can realize continuous and efficient observation of multiple targets in one imaging mission by autonomously performing multi-wave position and multi-parameter real-time calculation on board for irregularly distributed multiple targets, and combining the fast, flexible and efficient radio beam switching capability of the payload phased array antenna. Compared with the traditional multi-target independent observation method, the present invention can improve the multi-target observation efficiency;

[0037] 2. The present invention adopts a three-axis zero-momentum attitude control scheme for the agile platform system, which ensures the satellite's high-precision pointing, high stability, and rapid and agile maneuverability; the radar payload antenna is designed with a phased array antenna for one-dimensional large-angle scanning, which greatly reduces the weight, power consumption and cost of the antenna. The present invention gives full play to the rapid maneuverability of the agile platform and the rapid electronic scanning of the radar payload antenna, and plays an important advantage in the continuous observation of multiple targets.

[0038] 3. The present invention takes advantage of the millisecond-level rapid switching of the radio beam of the SAR satellite phased array antenna, and realizes multiple imaging of irregular multiple targets by continuously changing parameters multiple times after one startup, thus significantly improving the observation efficiency of satellite-borne SAR for irregular and complex multiple targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0040] Figure 1 It is a schematic diagram of the process of the present invention;

[0041] Figure 2 A task planning flow chart for the method of the present invention;

[0042] Figure 3 Schematic diagram of multi-target distribution of the method of the present invention. DETAILED DESCRIPTION

[0043] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0044] The present invention provides a satellite-borne SAR irregular multi-target observation method in which an agile platform and a radar payload are coordinated. According to the distribution law of multiple targets in irregular areas selected by users, satellite mission planning and imaging parameter design are performed. Continuous imaging of multiple targets is achieved by continuously changing the parameters of the satellite payload once the satellite is powered on, giving full play to the fast and agile switching capability of the planar phased array antenna in the distance direction of the radio wave beam, ensuring that the imaging interval between multiple targets is approximately in the millisecond level, and greatly improving the multi-target observation efficiency. In addition, the present invention designs the planar phased array antenna of the satellite-borne SAR system into a one-dimensional distance-direction large-angle scanning, which greatly reduces the weight, volume and cost of the entire satellite, and meets the user's demand for the use of light and small SAR satellites.

[0045] See also Figure 1 , Figure 1 This is a flowchart of a spaceborne SAR irregular multi-target observation method for coordinated agile platform and radar payload provided by an embodiment of the present invention. The method steps are as follows:

[0046] Step 1: According to user needs and satellite characteristics, multiple targets distributed along irregular areas are selected for mission planning;

[0047] Step 2: Satellite agile platform control design;

[0048] Step 3: Satellite working mode design;

[0049] Step 4: Design of radar payload antenna scanning mode;

[0050] Step 5: Design of SAR irregular multi-target observation mode;

[0051] Step 6: Design of multi-objective on-board real-time processing mode.

[0052] Furthermore, in step 1, multiple targets A to I distributed along irregular areas are selected according to user needs, and task planning is performed according to the distribution characteristics of the multiple targets. The task planning steps include the following:

[0053] Step 1.1: According to the satellite orbit elements, the satellite calculates the downward viewing angle θL of each target, determines the imaging width W, and selects the appropriate satellite platform side swing angle;

[0054] Step 1.2: Calculate the intervals between adjacent target points based on the target overpass time, determine the single mission duration of each target based on the maximum satellite power-on time and the number of multiple targets, and finally select the observation band length of a single target; determine the total number of satellite imaging times and the total mission duration;

[0055] Step 1.3: For continuous irregular multiple targets, after determining the imaging window of each target and the mission start time of the first target, send the satellite platform side swing angle to the attitude and orbit control subsystem T1 second in advance, so that the satellite platform attitude changes from the sun-facing state to the ground-facing level flight state; send the data transmission integrated package to the onboard data processor T2 seconds in advance. After receiving the command, the onboard processor ensures that each stand-alone module is powered on on time; send the target point information package to the payload system T3 seconds in advance;

[0056] Step 1.4: If an important target is found during this multi-target observation imaging mission, the current imaging mission does not need to be terminated, and the imaging parameter calculation and planning process can be carried out in parallel. If the multi-target field of view size in the next area is within the payload antenna beam scanning range, no attitude control is required. 8 seconds before the end of this mission, the payload software will autonomously calculate the radar parameters of this mission; if the multi-target field of view size exceeds the payload antenna beam scanning capability range, the imaging attitude control of the new target will be immediately switched after the current imaging is completed.

[0057] Furthermore, in step 2, in the control design of the satellite agile platform, a three-axis zero-momentum attitude control scheme is adopted for attitude and orbit control. When the payload is working, a high-precision star sensor and a fiber optic gyroscope are used for joint attitude determination to achieve high-precision attitude determination. A high-precision feedforward combined with a closed-loop feedback attitude control algorithm is used to drive a high-torque flywheel to achieve three-axis attitude stability control and rapid maneuvering of the satellite's ground-to-earth operation.

[0058] Furthermore, in step 3, in order to coordinate the rapid imaging of multiple targets by the satellite, the satellite is designed with two working modes: level flight and left and right side viewing. In the level flight mode, the satellite is designed with two-dimensional attitude guidance control to ensure the quality of SAR images; for the left and right side viewing mode, the satellite is designed with arbitrary side swing angle maneuvering control, and cooperates with the payload antenna to complete the rapid switching of the beam, so that the satellite working mode is flexible and maneuverable, and the satellite's ability to obtain information is enhanced.

[0059] Furthermore, in step 4, in order to give full play to the agility and speed of the satellite platform, and taking into account the constraints of imaging performance, the weight of the entire satellite, energy consumption and other conditions, the payload phased array antenna is designed with a one-dimensional large-angle scanning capability in the range direction, ensuring the rapid switching and large-angle scanning of the antenna range beam. Through the satellite yaw ±90 degrees maneuver, the antenna range and azimuth are interchangeably designed, ensuring the antenna azimuth's ability to scan forward and backward through a large-angle beam, improving the observation efficiency of multiple targets.

[0060] Furthermore, in the step 5, in the design of the irregular multi-target observation mode of the spaceborne SAR, the specific design idea includes the following steps:

[0061] Step 5.1: Considering the deviation of multi-target aiming accuracy caused by orbit altitude change, the satellite is designed with an onboard autonomous power-on time correction function. The satellite calculates the actual imaging power-on time of the satellite based on real-time orbit information, target point location information, and mission duration information, effectively ensuring the aiming accuracy of multiple targets;

[0062] Step 5.2: For irregular multi-target templates, the payload system has designed a continuous observation mode with autonomous switching of multiple wave positions. For a single startup imaging, the payload can autonomously calculate the multi-wave position radar parameters in advance based on the target point group sent by the satellite, and autonomously select the optimal observation wave position. At the same time, the payload system software has designed a millisecond-level wave position switching rate and a millisecond-level beam switching capability of the payload phased array antenna, which effectively improves the observation efficiency of multiple targets;

[0063] Step 5.3: The payload system sets the target number in the echo auxiliary data received on board according to the target observation order, which is convenient for the analysis of the on-board real-time processing module and ground data processing.

[0064] Furthermore, in step 6, the on-board real-time imaging processing module adopts a pipeline architecture solution, and the payload system sends the echo data to the on-board real-time processing module. The real-time processing module first performs data segmentation according to the target number of the SAR echo data; extracts relevant area data according to the specified longitude and latitude information of each target, and completes imaging processing on the satellite; performs key target detection and positioning processing on the imaging results, and transmits the processed target slices to the data transmission subsystem.

[0065] Figure 2 The present invention provides a schematic diagram of the distribution and timing of 9 irregular targets, with target numbers A to I, target overpass times t1 to t9, and single target imaging durations Δt1 to Δt9s (total imaging duration ΔT ≤ the longest satellite startup time), and the imaging duration Δt1 of the first target A is set to 10s. The present invention makes full use of the millisecond switching capability of the planar phased array antenna of the satellite-borne SAR system to the radio beam, and the interval between adjacent target imaging is less than 0s. The values ​​of the above parameters are shown in Table 1.

[0066] Table 1 Parameter values ​​of the embodiment

[0067]

[0068] The method of the present invention is used to perform performance simulation evaluation and analysis on the input 9 target points. In addition, the selected targets are imaged by 9 satellites powered on separately. However, since the relevant single machine needs to be powered on and off before and after each mission on the satellite, this observation method must take into account the minimum time interval between two imaging. If the satellite attitude maneuver is not considered, the maximum interval between any two imaging is 10s.

[0069] Table 2 Simulation evaluation results of the embodiment

[0070]

[0071]

[0072] According to Table 2, the total imaging time of the method of the present invention for observing the 9 target points input in the embodiment is about 98 seconds; if 9 independent observations are used, the total imaging time required is 180 seconds. It can be seen that the efficiency of the method of the present invention for irregular multi-target observation can be improved by 50%. Therefore, through the simulation analysis of the embodiment, the efficiency of the spaceborne SAR irregular multi-target observation method proposed by the present invention in which an agile platform and a radar payload are coordinated can be verified.

[0073] The present invention also provides a satellite-borne SAR irregular multi-target observation system based on the collaboration of an agile platform and a radar payload. The satellite-borne SAR irregular multi-target observation system based on the collaboration of an agile platform and a radar payload can be realized by executing the process steps of the satellite-borne SAR irregular multi-target observation method based on the collaboration of an agile platform and a radar payload, that is, technical personnel in this field can understand the satellite-borne SAR irregular multi-target observation method based on the collaboration of an agile platform and a radar payload as a preferred implementation of the satellite-borne SAR irregular multi-target observation system based on the collaboration of an agile platform and a radar payload.

[0074] Specifically, a spaceborne SAR irregular multi-target observation system based on the collaboration of an agile platform and a radar payload is provided according to the present invention, comprising:

[0075] Module M100: Satellite mission planning and imaging parameter setting based on the distribution pattern of multiple targets in irregular areas selected by the user;

[0076] Module M200: Continuous imaging of multiple targets is achieved by controlling the satellite to continuously change the parameters of the payload once it is powered on;

[0077] Module M300: Data cutting according to the target number of SAR echo data; extracting relevant area data according to the specified longitude and latitude information of each target, and completing imaging processing on the satellite; performing key target detection and positioning processing on the imaging results, and transmitting the processed target slices to the data transmission subsystem.

[0078] The module M100 comprises:

[0079] Module M101: Calculate the downward viewing angle θL of each target according to the number of satellite orbit elements, determine the imaging width W, and obtain the matching satellite platform side swing angle;

[0080] Module M102: Calculate the intervals between adjacent target points based on the target overpass time, determine the single mission duration of each target based on the maximum satellite power-on time and the number of multiple targets, and finally select the observation band length of a single target; determine the total number of satellite imaging times and the total mission duration.

[0081] The module M200 comprises:

[0082] Module M201: For continuous irregular multiple targets, after determining the imaging window of each target and the mission start time of the first target, send the satellite platform side swing angle to the attitude and orbit control subsystem T1 second in advance, so that the satellite platform attitude changes from the sun-facing state to the ground-facing level flight state; send the data transmission integrated package to the onboard data processor T2 seconds in advance, and after receiving the command, the onboard processor ensures that each stand-alone module is powered on on time; send the target point information package to the payload system T3 seconds in advance;

[0083] Module M202: During this multi-target observation and imaging mission, for targets that are set as important, the current imaging mission will not be terminated, and imaging parameter calculation and planning will be carried out in parallel; if the multi-target field of view size in the next area is within the payload antenna beam scanning range, no attitude control is required, and after the current mission is completed, the payload software will autonomously calculate the radar parameters of the mission in advance; if the multi-target field of view size exceeds the payload antenna beam scanning capability, after the current imaging is completed, it will switch to imaging attitude control for the new target.

[0084] In the module M200:

[0085] In order to address the deviation of multi-target aiming accuracy caused by orbital altitude changes, the satellite can automatically correct the power-on time. The actual satellite imaging power-on time is calculated based on real-time orbit information, target point location information, and mission duration information.

[0086] For irregular multi-target templates, the control payload system adopts a continuous observation mode with autonomous switching of multiple wave positions. For one-time imaging, the control payload system autonomously calculates the multi-wave position radar parameters in advance according to the target point group sent by the satellite, and autonomously selects the matching observation wave position. Among them, the payload system software adopts a millisecond-level wave position switching rate and millisecond-level beam switching of the payload phased array antenna.

[0087] The control payload system sets the target number in the echo auxiliary data received on board according to the target observation order for analysis by the on-board real-time processing module and ground data processing.

[0088] Those skilled in the art know that, in addition to realizing the system and its various devices, modules, and units provided by the present invention in a purely computer-readable program code, it is entirely possible to realize the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered as a hardware component, and the devices, modules, and units included therein for realizing various functions can also be regarded as structures within the hardware component; the devices, modules, and units for realizing various functions can also be regarded as both software modules for realizing the method and structures within the hardware component.

[0089] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A spaceborne SAR irregular multi-target observation method in which an agile platform and a radar payload are coordinated, characterized in that: include: Step S100: performing satellite mission planning and imaging parameter setting according to the multi-target distribution law in the irregular area selected by the user; Step S200: Continuous imaging of multiple targets is achieved by continuously changing the parameters of the satellite payload once it is powered on.

2. The spaceborne SAR irregular multi-target observation method in which the agile platform and the radar payload are coordinated according to claim 1 is characterized in that: The step S100 includes: Step S101: Calculate the downward viewing angle θL of each target according to the number of satellite orbit elements, determine the imaging width W, and obtain the matching satellite platform side swing angle; Step S102: Calculate the intervals between adjacent target points based on the target over-the-top moment, determine the single mission duration of each target based on the maximum satellite power-on time and the number of multiple targets, and finally select the observation band length of a single target; determine the total number of satellite imaging times and the total mission duration.

3. The spaceborne SAR irregular multi-target observation method in which the agile platform and the radar payload are coordinated according to claim 2 is characterized in that: The step S200 includes: Step S201: For continuous irregular multiple targets, after determining the task start time of each target imaging window and the first target, the satellite platform side swing angle is sent to the attitude and orbit control subsystem T1 seconds in advance, so that the satellite platform attitude changes from the sun-facing state to the ground-facing level flight state; the data transmission integrated package is sent to the onboard data processor T2 seconds in advance, and after the onboard processor receives the instruction, it ensures that each stand-alone module is powered on on time; the target point information package is sent to the payload system T3 seconds in advance; Step S202: During this multi-target observation and imaging mission, for targets that are discovered and set as important, the current imaging mission will not be terminated, and imaging parameter calculation and planning processing will be carried out in parallel; if the multi-target field of view size in the next area is within the payload antenna beam scanning range, no attitude control is required, and after the current mission is completed, the payload software will autonomously calculate the radar parameters of the mission in advance; if the multi-target field of view size exceeds the payload antenna beam scanning capability, after the current imaging is completed, the imaging attitude control of the new target will be switched.

4. The spaceborne SAR irregular multi-target observation method in which the agile platform and the radar payload are coordinated according to claim 3 is characterized in that: In the process of changing the attitude of the satellite platform from the state of flying toward the sun to the state of flying toward the ground, attitude and orbit control adopts three-axis zero-momentum attitude control, and when the payload is working, attitude determination is achieved by using a star sensor and a fiber optic gyroscope for joint attitude determination, and a flywheel is driven by feedforward combined with closed-loop feedback attitude control to achieve three-axis attitude control and maneuvering of the satellite working toward the ground.

5. The spaceborne SAR irregular multi-target observation method in which the agile platform and the radar payload are coordinated according to claim 1 is characterized in that: The payload phased array antenna adopts one-dimensional large-angle scanning in the range direction. By maneuvering the satellite to yaw ±90 degrees, the antenna range and azimuth directions are interchanged, thereby obtaining the antenna's ability to scan forward and backward in the azimuth direction through a large-angle beam.

6. The spaceborne SAR irregular multi-target observation method in which the agile platform and the radar payload are coordinated according to claim 1 is characterized in that: In step S200: In order to address the deviation of multi-target aiming accuracy caused by orbital altitude changes, the satellite can automatically correct the power-on time. The actual satellite imaging power-on time is calculated based on real-time orbit information, target point location information, and mission duration information. For irregular multi-target templates, the control payload system adopts a continuous observation mode with autonomous switching of multiple wave positions. For one-time imaging, the control payload system autonomously calculates the multi-wave position radar parameters in advance based on the target point group sent by the satellite, and autonomously selects the matching observation wave position. Among them, the payload system software adopts a millisecond-level wave position switching rate and millisecond-level beam switching of the payload phased array antenna.

7. The spaceborne SAR irregular multi-target observation method in which the agile platform and the radar payload are coordinated according to claim 1 is characterized in that: In step S200: The control payload system sets the target number in the echo auxiliary data received on board according to the target observation order for analysis by the on-board real-time processing module and ground data processing.

8. The spaceborne SAR irregular multi-target observation method in which the agile platform and the radar payload are coordinated according to claim 1 is characterized in that: Also includes: Step S300: Data cutting is performed according to the target number of the SAR echo data; relevant area data is extracted according to the designated longitude and latitude information of each target, and imaging processing is completed on the satellite; The imaging results are processed for key target detection and positioning, and the processed target slices are transmitted to the data transmission subsystem.

9. A spaceborne SAR irregular multi-target observation system based on the collaboration of an agile platform and a radar payload, characterized in that: include: Module M100: Satellite mission planning and imaging parameter setting based on the distribution pattern of multiple targets in irregular areas selected by the user; Module M200: Continuous imaging of multiple targets is achieved by controlling the satellite to start up once and continuously change the payload parameters.

10. A satellite, characterized in that: The observation is performed by using the spaceborne SAR irregular multi-target observation method in which the agile platform and the radar payload are coordinated as described in any one of claims 1 to 8.

Images