Multi-satellite networking moonlet long-time sequence observation mode construction method and system

Abstract

The invention provides a multi-satellite networking moonlet long-time sequence observation mode construction method and system. The method comprises the following steps: carrying out single-satellite radar load system capability construction; establishing a satellite observation mode based on single target distribution; establishing a satellite agile platform and load antenna collaborative observation mode based on multi-target distribution; designing an SAR long-time observation orbit of multi-satellite networking; the invention relates to a satellite autonomous control mode design based on multi-satellite cooperative work. According to the method, the situation that the longest starting time of a moonlet at a time is restrained by energy, heat consumption and solid storage capacity of the whole satellite is fully considered, and continuous observation on the ground cannot be carried out for a long time. According to the invention, a multi-satellite networking mode is adopted to carry out long-time sequence observation on a target area, and the dynamic trend of a hot target is continuously monitored. The method gives full play to the constellation efficiency of multi-satellite networking, can be widely applied to the field of small satellite constellation networking, and has important application value.

Description

Technical Field

[0001] The present invention relates to the technical field of aerospace systems, and in particular, to a method and system for constructing a long-time series observation mode for small satellites in a multi-satellite network. Background Art

[0002] Synthetic Aperture Radar (SAR) is an active remote sensing technology that can obtain images all day and all weather, even at night or during cloud cover, obtaining rich details of ground objects, having a certain penetration ability, effectively making up for the deficiencies of optical remote sensing satellites, and has been widely used in the aerospace and national defense fields. With the rapid development of low-cost and lightweight low-orbit small satellites, the number of on-orbit small satellites is gradually increasing, and multi-satellite networking has become an important development direction for low-orbit small satellites. Taking the ICEYE-X constellation of Finnish company ICEYE and the Capella small satellite constellation of American company Capella as typical representatives, most small satellites at home and abroad can greatly shorten the revisit cycle and improve the temporal resolution of targets in hot spots through multi-satellite networking observation methods, meeting the high-frequency observation requirements in hot spots.

[0003] Patent document CN117556579A discloses a multi-satellite collaborative optimal observation method, including establishing a constraint satisfaction model; gridifying targets in an irregular area, designing a basic observation mode based on grid segmentation, and generating an observation plan. On this basis, a normalized regional target gridification algorithm and a basic observation mode generation algorithm based on grid segmentation are designed in the first two stages respectively, and a serial variable neighborhood tabu search algorithm and a parallel genetic algorithm combined with neighborhood search are designed in the third stage respectively. However, this method is not suitable for multi-satellite collaborative long-time series tracking and monitoring observations of hot spots.

[0004] Patent document CN107679748A discloses a space-ground joint operation method for autonomous planning of constellation observation tasks, and proposes a space-ground joint operation method for constellation task planning under the condition of limited ground TT&C resources. However, the multi-satellite task planning method of this invention is not suitable for the multi-satellite networking long-time series observation method.

[0005] Patent document CN109145325A discloses a multi-satellite networking collaborative observation method for industry needs, including the following steps: establishing a diversified demand model for typical application themes; establishing a multi-source satellite observation capability model; establishing a multi-source satellite collaborative observation strategy model; and performing correlation analysis on the diversified demand model and the multi-source satellite observation capability model according to the multi-source satellite collaborative observation strategy model. However, the long-time series observation method is not mentioned in the multi-satellite networking collaborative observation method of this invention.

[0006] The paper "Multi-Satellite Cooperative Observation Method Based on Regional Target Gridization" was published in the Journal of University of Chinese Academy of Sciences in 2023. This article proposed a regional target gridization observation method for the cooperation of multiple SAR satellites facing regional targets. This method is applicable to the repeated observation of regional targets by multi-satellite cooperation and is not suitable for the continuous observation of targets by multi-satellite cooperation.

[0007] The paper "A Multi-Satellite Cooperative Planning Algorithm for Periodic Continuous Observation Tasks" was published in Radio Engineering in 2022. This article proposed a continuous observation method with time windows for multiple satellites. However, the satellite orbit was not designed to be maintained in the article, resulting in the failure to achieve continuous stitching of the target area.

[0008] To sum up, regarding the research on the long-time series observation method of spaceborne SAR with multi-satellite networking, there are currently no relevant invention patents in China. Facing the rapid development of low-orbit small satellites, in the design of small satellites, the maximum single-on time is often restricted by multiple factors such as the overall satellite energy, heat dissipation, volume, weight, and cost. As a result, the maximum single-on time is limited and cannot meet the demand for continuous monitoring of the dynamic changes of targets in hot spots with long-time series.

[0009] Therefore, there is an urgent need in the market for a method and system for constructing a long-time series observation mode of small satellites with multi-satellite networking. Summary of the Invention

[0010] Aiming at the defects in the prior art, the purpose of the present invention is to provide a method and system for constructing a long-time series observation mode of small satellites with multi-satellite networking.

[0011] According to a method for constructing a long-time series observation mode of small satellites with multi-satellite networking provided by the present invention, it includes:

[0012] Step S1: Construct the system capabilities of a single satellite radar payload;

[0013] Step S2: For the single target observation area D 1 , based on the depression angle θ 1 of the target D L , establish a satellite observation mode based on the single target distribution;

[0014] Step S3: According to the number D n and positions of the target points, establish a cooperative observation mode of the satellite agile platform and the payload antenna based on the multi-target distribution;

[0015] Step S4: Construct a long-time observation orbit of SAR with multi-satellite networking;

[0016] Step S5: Construct a satellite autonomous control mode based on multi-satellite cooperative work.

[0017] Preferably, the step S1 includes: designing the payload antenna for one-dimensional radio beam scanning, and making the antenna beam pointing fixed in the azimuth and range directions through the cooperation between the agile platform and the payload antenna's electronic scanning.

[0018] Preferably, the step S2 includes: θ max represents the maximum scanning ability of the antenna beam,

[0019] When θ L <θ max , the satellite adopts a high-resolution imaging mode based on the long-time series of the level flight attitude;

[0020] When θ L >θ max , through the side-sway maneuver of the satellite agile platform combined with the small-angle electronic scanning ability of the payload antenna, the high-resolution imaging based on the long-time series of the left and right side-looking attitudes is realized collaboratively.

[0021] Preferably, the step S3 includes:

[0022] If n targets are evenly distributed in the azimuth direction, the satellite completes the continuous observation of multiple targets through the range-direction electronic scanning of the payload antenna during one pass;

[0023] If n targets are evenly distributed in the range direction, relying on the collaborative work of the satellite agile platform's attitude maneuver and the payload antenna beam's electronic scanning ability, the continuous observation of multiple targets with a large swath is completed;

[0024] If n targets are irregularly distributed in the range and azimuth directions, the satellite conducts autonomous mission planning according to the number and positions of the n targets, generates the imaging windows T n of the n targets, ensuring that the total imaging duration T n ≤2 min; the satellite sends the imaging command sheets for n times to the satellite payload, and the payload independently conducts radar parameter calculation and power-on control for n times to complete the continuous multiple imaging based on the irregular multi-target area.

[0025] Preferably, the relying on the collaborative work of the satellite agile platform's attitude maneuver and the payload antenna beam's electronic scanning ability to complete the continuous observation of multiple targets with a large swath includes the following sub-steps:

[0026] Step S3.1: Before imaging, the satellite's attitude pitch angle is maneuvered to the required squint angle θ 1 position, and during imaging, the θ s1 is switched through the range-direction beam scanning of the antenna;

[0027] Step S3.2: The satellite's pitch maneuver is used to change the forward squint angle to the squint angle θ 2 position, and the θ s2 is switched through the range-direction beam scanning of the payload antenna;

[0028] Step S3.3: Manoeuvre the satellite's pitch angle to the squint angle θ 3 to the required squint angle position, and rely on the range beam scanning switching of the payload antenna by θ s3 ;

[0029] Step S3.4: Stitch the three echo data along the range width.

[0030] Preferably, the step S4 includes:

[0031] Step S4.1: Assume the orbital parameters of the previous satellite (t 0 , a 1 , e 1 , i 1 , Ω 1 , ω 1 , M 1 ), where t 0 is the epoch time, a 1 is the semi-major axis, e 1 is the eccentricity, i 1 is the orbital inclination, Ω 1 is the right ascension of the ascending node, ω 1 is the argument of perigee, and M 1 is the true anomaly;

[0032] Step S4.2: According to the imaging time interval Δt, calculate the orbit that repeats the ground track of the previous satellite and has an access interval difference of Δt, satisfying:

[0033]

[0034] where ω e is the Earth's rotation rate;

[0035] Step S4.3: Calculate the imaging intervals Δt 1 , Δt 2 ,... Δt n of each satellite according to the observation target time series, and calculate the required orbital parameters of each satellite based on the above formula.

[0036] Preferably, the step S5 includes:

[0037] Step S5.1: The ground operation and control system prepares and uploads mission instructions for the first satellite, Sat01. After receiving the instructions, it controls the satellite agile platform to maintain the attitude control towards the earth T1 seconds in advance, powers on and controls the satellite data transmission and payload systems T2 seconds in advance, the satellite autonomously corrects the on-board imaging parameters according to the real-time orbit information T3 seconds in advance, and sends the target point information, imaging start and end times, and imaging waveband information of Satellite 01 to Sat02 via the inter-satellite microwave communication link T4 seconds in advance, where T1 > T2 > 100 seconds and T3 > T4 > 40 seconds; at time T, Sat01 satellite conducts long-time sequence observation imaging for Δt.

[0038] Step S5.2: After receiving the target and imaging parameter information sent by Sat01, Sat02 also sends the target point information, imaging start and end times, and imaging waveband information of Sat02 to Sat03 via the inter-satellite microwave communication link according to the task timing plan in Step S5.1; at time T + Δt, Sat02 satellite conducts long-time sequence observation imaging for Δt.

[0039] Step 5.3: After receiving the target and imaging parameter information sent by Sat02, Sat03 also sends the target point information, imaging start and end times, and imaging waveband information of Sat03 to Sat04 via the inter-satellite microwave communication link according to the task timing plan in Step S5.1; at time T + 2Δt, Sat03 satellite conducts long-time sequence observation imaging for Δt.

[0040] According to a small satellite long-time sequence observation mode construction system for multi-satellite networking provided by the present invention, it includes:

[0041] Module M1: Construct the capabilities of the single-satellite radar payload system;

[0042] Module M2: For the single target observation area D 1 , based on the target D 1 's downward viewing angle θ L Establish a satellite observation mode based on the single target distribution;

[0043] Module M3: According to the number and positions of target points D n Establish a collaborative observation mode of the satellite agile platform and the payload antenna based on the multi-target distribution;

[0044] Module M4: Construct the long-time observation orbit of the multi-satellite networking SAR;

[0045] Module M5: Construct a satellite autonomous control mode based on multi-satellite collaborative work.

[0046] Preferably, the module M1 includes: designing the payload antenna for one-dimensional radio beam scanning, and making the antenna beam pointing fixed in the azimuth and range directions through the cooperation between the agile platform and the payload antenna's electronic scanning method.

[0047] Preferably, the module M2 includes: θ max representing the maximum scanning ability of the antenna beam,

[0048] When θ L <θ max , the satellite adopts a high-resolution imaging mode based on the long-time series of the level flight attitude;

[0049] When θ L >θ max , through the side-sway maneuver of the satellite agile platform combined with the small-angle electronic scanning ability of the payload antenna, the high-resolution imaging based on the long-time series of the left and right side-looking attitudes is jointly achieved.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] 1. In the design of the payload system of the present invention, the phased array antenna of the radar payload is designed for one-dimensional beam scanning. By reducing the number of component channels in one dimension of the antenna, the weight and power consumption of a single satellite are effectively reduced, which is beneficial to the launch of multiple satellites by a single carrier rocket.

[0052] 2. For a single target area, the present invention establishes an efficient continuous observation mode of the satellite in level flight, without the need for satellite attitude maneuver cooperation, and effectively improves the target observation efficiency relying on the payload antenna; for a multi-target area, a cooperative working mode between the satellite agile platform and the payload antenna is established. Through the satellite attitude pitch maneuver combined with the large-angle scanning method of the payload beam, multi-target wide-swath efficient observation can be achieved.

[0053] 3. Aiming at the problem that small satellites are restricted by factors such as energy, weight and cost and cannot continuously observe the target situation for a long time, the present invention designs the orbit through the multi-satellite cooperation mode, and adopts the multi-satellite networking method to conduct long-time series observation on the target area, so as to realize the continuous monitoring of the dynamic trend of hot targets. The present invention gives full play to the constellation efficiency of multi-satellite networking, can be widely applied to the field of small satellite constellation networking, and has important application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] By reading the following detailed description of the non-limiting embodiments with reference to the accompanying drawings, other features, objects and advantages of the present invention will become more obvious:

[0055] Figure 1 It is a schematic flow chart of the method of the present invention;

[0056] Figure 2Schematic diagram of the multi-satellite networking long-term observation working mode of the method of the present invention. Specific embodiments

[0057] The present invention will be 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 do not limit the present invention in any form. It should be noted that those of ordinary skill in the art can make several changes and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0058] The present invention first conducts antenna lightweight design in the design of the single-satellite payload system; for a single target area, a satellite level flight efficient continuous observation mode is established; for multiple target areas, a collaborative working mode of the satellite agile platform and the payload antenna is established. On the basis of a single satellite, the present invention conducts orbit keeping design for the multi-satellite networking collaborative mode, and at the same time establishes a satellite autonomous control method. Aiming at the problem that small satellites are restricted by factors such as energy, weight and cost and cannot continuously observe the target situation for a long time, the present invention adopts a multi-satellite networking mode to conduct long-time series observation of the target area, and realizes continuous monitoring of the dynamic trend of hot targets.

[0059] Embodiment 1

[0060] According to a method for constructing a long-time series observation mode of small satellites with multi-satellite networking provided by the present invention, as Figure 1 and Figure 2 shown, it includes:

[0061] Step S1: Construct the capabilities of the single-satellite radar payload system. The step S1 includes: designing the payload antenna as a one-dimensional electric beam scanning, and making the antenna beam pointing fixed in the azimuth and range directions through the electrical scanning cooperation method of the agile platform and the payload antenna. The selection of the antenna size and the design of the antenna scheme are important steps in the design of the spaceborne SAR system. Once the payload antenna size is designed, the antenna beam scanning capability design is carried out according to the payload imaging requirements. In order to give full play to the high-precision, high-reliability and high-stability attitude control capabilities of the satellite agile platform and to meet the long-term stable observation requirements of the single-satellite spaceborne SAR, the payload antenna is designed as a one-dimensional electric beam scanning, effectively reducing the weight of the antenna. Through the electrical scanning cooperation method of the agile platform and the payload antenna, the antenna beam pointing is fixed in the azimuth and range directions, and long-time series continuous observation imaging is carried out.

[0062] Step S2: Establish a satellite observation mode based on the single target distribution. The step S2 includes: for the single target observation area D 1 , according to the target D 1 's downward viewing angle θ L , θ L <θmax , the satellite can adopt a high-resolution imaging mode based on a long time series of horizontal flight postures; θ L > θ max , through the side-sway maneuver of the satellite agile platform combined with the small-angle electrical scanning ability of the payload antenna, the high-resolution imaging based on the long time series of left and right side-looking postures is realized synergistically. Among them, θ max represents the maximum scanning ability of the antenna beam.

[0063] Step S3: Establishment of a collaborative observation mode for the satellite agile platform and the payload antenna based on multi-target distribution. For a large-scale multi-target observation area D = {Tar01 Tar02 Tar03...}, establish a collaborative working mode for the satellite agile platform and the payload antenna based on multi-target distribution. According to the number D n and positions of the target points, if n targets are evenly distributed along the azimuth direction, the satellite completes continuous observation of multiple targets through the range-direction electrical scanning of the payload antenna during one pass.

[0064] If n targets are evenly distributed along the range direction, relying on the collaborative work of the satellite agile platform attitude maneuver and the payload antenna beam electrical scanning ability, complete continuous observation of multiple targets with a large swath. The specific steps are as follows:

[0065] Step S3.1: Before imaging, the pitch angle of the satellite attitude maneuvers to the squint angle θ 1 position required for forward squint. During imaging, switch θ s1 through the range-direction beam scanning of the antenna;

[0066] Step S3.2: Through the satellite pitch maneuver, the forward squint angle is adjusted to the squint angle θ 2 position, and switch θ s2 through the range-direction beam scanning of the payload antenna;

[0067] Step S3.3: Through the satellite pitch angle maneuver to the squint angle θ 3 position required for squint, relying on the range-direction beam scanning of the payload antenna to switch θ s3 ;

[0068] Step S3.4: Stitch the three echo data along the range-direction swath.

[0069] If n targets are irregularly distributed along the range direction and the azimuth direction, the satellite conducts autonomous mission planning according to the number and positions of the n targets, generates imaging windows T n for the n targets, ensuring that the total imaging duration T n of the n imaging times ≤ 2 min; the satellite sends the n imaging instruction sheets to the satellite payload, and the payload independently conducts n radar parameter calculations and power-on control to complete continuous multiple imaging based on the irregular multi-target area.

[0070] Step S4: Design of the long - time observation orbit for multi - satellite networking SAR. The said step S4 includes:

[0071] Step S4.1: Assume the orbital parameters of the previous satellite (t 0 , a 1 , e 1 , i 1 , Ω 1 , ω 1 , M 1 ), where t 0 is the epoch time, a 1 is the semi - major axis, e 1 is the eccentricity, i 1 is the orbital inclination, Ω 1 is the right ascension of the ascending node, ω 1 is the argument of perigee, M 1 is the true anomaly.

[0072] Step S4.2: According to the imaging time interval Δt, calculate the orbit that repeats the ground track of the previous satellite and has an access interval difference of Δt, satisfying:

[0073]

[0074] where ω e is the Earth's rotation rate.

[0075] Step S4.3: Calculate the imaging intervals Δt 1 , Δt 2 ,... Δt n of each satellite according to the observation target time series, and calculate the orbital parameters required for each satellite based on the above formula.

[0076] Step S5: Design of the satellite autonomous control mode based on multi - satellite collaborative work. As Figure 2 shown, the said step S5 includes:

[0077] Step S5.1: The ground operation and control system prepares and uploads mission instructions for the first satellite, Sat01. After receiving the instructions, it controls the satellite agile platform to maintain the attitude control towards the ground T1 seconds in advance, powers on the satellite data transmission and payload systems T2 seconds in advance, the satellite autonomously corrects the on - orbit imaging parameters according to the real - time orbit information T3 seconds in advance, and sends the target point information, imaging start and end times, and imaging waveband information of the 01 satellite to Sat02 via the inter - satellite microwave communication link T4 seconds in advance, where T1 > T2 > 100 s, T3 > T4 > 40 s; at time T, the Sat01 satellite performs Δt long - time series observation imaging.

[0078] Step S5.2: After receiving the target and imaging parameter information sent by Sat01 satellite, Sat02 satellite also sends the target point information of Sat02 satellite, the imaging start and end times, and the imaging waveband information to Sat03 satellite through the inter-satellite microwave communication link according to the task timing plan in Step S5.1; at T+△t, Sat02 satellite performs long-time series observation imaging for △t.

[0079] Step 5.3: After receiving the target and imaging parameter information sent by Sat02 satellite, Sat03 satellite also sends the target point information of Sat03 satellite, the imaging start and end times, and the imaging waveband information to Sat04 satellite through the inter-satellite microwave communication link according to the task timing plan in Step S5.1; at T+2△t, Sat03 satellite performs long-time series observation imaging for △t.

[0080] Based on the single-satellite mode, in Step S2, a satellite observation mode with a single target distribution is established, and in Step S3, a cooperative working mode of a multi-target distributed satellite agile platform and a payload antenna is established. This mode is also applicable to the multi-satellite networking mode, and continuous monitoring of single targets and multi-targets in a long-time series is completed through multi-satellite cooperation.

[0081] Furthermore, the effects of the method for constructing a long-time series observation mode of small satellites in multi-satellite networking of the present invention are specifically described as follows in combination with simulation data:

[0082] Three synthetic aperture radar satellites are selected for networking design, with satellite numbers Sat01, Sat02, and Sat03 respectively. The orbit type is selected as a low-inclination orbit, the orbit height is about 520 km, the viewing angle range is designed as 38 - 40.2°, and the satellite level flight working mode is selected. The strip imaging mode is selected, the range resolution is designed as 2 m, and the range imaging swath is designed as 21 km.

[0083] According to the method of the present invention, the multi-satellite networking orbit design is carried out. The output orbit parameters in the embodiment are shown in Table 1, and the output observation parameters are shown in Table 2:

[0084] Table 1 Output orbit parameters in the embodiment

[0085]

[0086]

[0087] Table 2 Output observation parameters in the embodiment

[0088] satellite imaging start time observation length Sat01 2024-1-1 8:00:00 800km Sat02 2024-1-1 8:02:00 801km Sat03 2024-1-1 8:04:00 802km

[0089] By using the method of the present invention, through the network collaboration of the orbital designs of three satellites, continuous observations of multiple targets over a long time series are achieved. With each satellite operating for 2 minutes and the average observation length being 800 km, after the three satellites are networked and work together for 6 minutes, a mapping belt length of up to 2403 km is obtained, giving full play to the constellation efficiency. Therefore, through the simulation analysis of the embodiments, the efficiency of a method for designing a long time series observation mode of small satellites with multi-satellite networking proposed by the present invention can be verified.

[0090] Embodiment 2

[0091] The present invention also provides a system for constructing a long time series observation mode of small satellites with multi-satellite networking. The system for constructing a long time series observation mode of small satellites with multi-satellite networking can be implemented by executing the process modules of the method for constructing a long time series observation mode of small satellites with multi-satellite networking. That is, those skilled in the art can understand the method for constructing a long time series observation mode of small satellites with multi-satellite networking as a preferred implementation manner of the system for constructing a long time series observation mode of small satellites with multi-satellite networking.

[0092] According to a system for constructing a long time series observation mode of small satellites with multi-satellite networking provided by the present invention, it includes:

[0093] Module M1: Construct the capabilities of a single satellite radar payload system. Module M1 includes: Design the payload antenna as a one-dimensional radio beam scanning, and through the cooperation between the agile platform and the electrical scanning of the payload antenna, make the pointing of the antenna beam fixed in the azimuth and range directions.

[0094] Module M2: For the single target observation area D 1 , based on the target D 1 's depression angle θ L Establish a satellite observation mode based on the single target distribution. Module M2 includes: θ max Represents the maximum scanning ability of the antenna beam. When θ L < θ max , the satellite adopts a high-resolution imaging mode based on a long time series of level flight attitudes. When θ L > θ max , through the side-sway maneuver of the satellite agile platform combined with the small-angle electrical scanning ability of the payload antenna, jointly achieve high-resolution imaging based on a long time series of left and right side-looking attitudes.

[0095] Module M3: According to the number of target points D nAnd position, establish a cooperative observation mode of the satellite agile platform and the payload antenna based on multi-objective distribution. Module M3 includes: If n targets are evenly distributed along the azimuth direction, the satellite can complete continuous observation of multiple targets through the range-direction electronic scanning of the payload antenna during one pass. If n targets are evenly distributed along the range direction, relying on the collaborative work of the satellite agile platform attitude maneuver and the payload antenna beam electronic scanning ability, continuous observation of multiple targets with a large swath is completed. If n targets are irregularly distributed along the range direction and the azimuth direction, the satellite conducts autonomous mission planning according to the number and position of the n targets, and generates an imaging window T n for the n targets, ensuring that the total imaging duration T n ≤2 min; the satellite sends the n imaging command sheets to the satellite payload, and the payload independently calculates the radar parameters n times and performs power-on control to complete continuous multiple imaging based on the irregular multi-target area.

[0096] Relying on the collaborative work of the satellite agile platform attitude maneuver and the payload antenna beam electronic scanning ability, continuous observation of multiple targets with a large swath is completed, including the following sub-modules: Module M3.1: Before imaging, the satellite's attitude pitch angle is maneuvered to the oblique view angle θ 1 required for forward squint, and during imaging, the θ s1 is switched through the range-direction beam scanning of the antenna; Module M3.2: The satellite's pitch maneuver is used to move the forward oblique view angle to the oblique view angle θ 2 , and the θ s2 is switched through the range-direction beam scanning of the payload antenna; Module M3.3: The satellite's pitch angle is maneuvered to the oblique view angle position required for squint θ 3 , and the θ s3 is switched relying on the range-direction beam scanning of the payload antenna; Module M3.4: The three echo data are spliced along the range-direction swath.

[0097] Module M4: Construction of the SAR long-time observation orbit for multi-satellite networking. Module M4 includes: Module M4.1: Assume the orbital parameters of the previous satellite (t 0 , a 1 , e 1 , i 1 , Ω 1 , ω 1 , M 1 ), where t 0 is the epoch time, a 1 is the semi-major axis, e 1 is the eccentricity, i 1 is the orbital inclination, Ω 1 is the right ascension of the ascending node, ω 1 is the argument of perigee, and M 1 is the true anomaly. Module M4.2: According to the imaging time interval Δt, calculate the orbit that repeats the ground track of the previous satellite and has an access interval difference of Δt, satisfying:

[0098]

[0099] where ω e is the Earth's rotation rate. Module M4.3: Calculate the imaging intervals Δt 1 、Δt 2 、...Δt n of each satellite based on the observed target time series, and calculate the orbital parameters required for each satellite based on the above formula.

[0100] Module M5: Construct a satellite autonomous control mode based on multi-satellite collaborative operation. Module M5 includes:

[0101] Module M5.1: The ground operation and control system prepares and uploads task instructions for the first satellite, Sat01. After receiving the instructions, it controls the satellite agile platform to maintain the attitude control towards the ground T1 seconds in advance, powers on the satellite data transmission and payload systems T2 seconds in advance, the satellite autonomously corrects the on-board imaging parameters based on the real-time orbital information T3 seconds in advance, and sends the target point information, imaging start and end times, and imaging waveband information of Satellite 01 to Sat02 via the inter-satellite microwave communication link T4 seconds in advance, where T1 > T2 > 100 s, T3 > T4 > 40 s; at time T, Sat01 satellite performs Δt long-time series observation imaging. Module M5.2: After receiving the target and imaging parameter information sent by Sat01, Sat02 satellite also sends the target point information, imaging start and end times, and imaging waveband information of Sat02 to Sat03 via the inter-satellite microwave communication link according to the task timing plan of Module M5.1; at time T + Δt, Sat02 satellite performs Δt long-time series observation imaging. Module 5.3: After receiving the target and imaging parameter information sent by Sat02, Sat03 satellite also sends the target point information, imaging start and end times, and imaging waveband information of Sat03 to Sat04 via the inter-satellite microwave communication link according to the task timing plan of Module M5.1; at time T + 2Δt, Sat03 satellite performs Δt long-time series observation imaging.

[0102] Those skilled in the art know that, in addition to implementing the system and its various devices, modules, and units provided by the present invention in the form of pure computer-readable program code, the method steps can be logically programmed to enable the system and its various devices, modules, and units provided by the present invention to be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. to achieve the same functions. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered as a kind of hardware component, and the devices, modules, and units included therein for implementing various functions can also be regarded as the structures within the hardware component; the devices, modules, and units for implementing various functions can also be regarded as either software modules for implementing the method or structures within the hardware component.

[0103] The specific embodiments of the present invention have been described above. 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 do not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for constructing a long-time series observation mode of a multi-satellite network, characterized in that: include: Step S1: construct the single-satellite radar payload system capability; Step S2: For a single target observation area D1, according to the downward viewing angle θ of the target D1 L Establish a satellite observation model based on single target distribution; Step S3: According to the number of target points D n and position, and establish a collaborative observation mode between the satellite agile platform and the payload antenna based on multi-target distribution; Step S4: constructing a multi-satellite networked SAR long-term observation orbit; Step S5: constructing a satellite autonomous control mode based on multi-satellite collaborative work.

2. The method for constructing a long-time series observation mode of a multi-satellite network according to claim 1, characterized in that: The step S1 includes: designing the payload antenna to be a one-dimensional electric wave beam scan, and making the antenna beam pointing fixed in azimuth and range directions by coordinating the agile platform with the electric wave scanning of the payload antenna.

3. The method for constructing a long-time series observation mode of a multi-satellite network according to claim 1, characterized in that: The step S2 comprises: max Indicates the maximum scanning capability of the antenna beam. When θ L <θ max ,The satellite adopts a high-resolution imaging mode based on a long time series of level flight attitude; When θ L >θ max Through the side-swing maneuver of the satellite agile platform combined with the small-angle electronic scanning capability of the payload antenna, high-resolution imaging based on a long-term series of left and right side-view attitudes is collaboratively achieved.

4. The method for constructing a long-time series observation mode of a multi-satellite network according to claim 1, characterized in that: The step S3 comprises: If n targets are evenly distributed in azimuth, the satellite can complete continuous observation of multiple targets in one pass by electronically scanning the range direction of the payload antenna; If n targets are evenly distributed along the distance, the satellite agile platform attitude maneuver and the payload antenna beam electronic scanning capability can work together to complete multi-target wide-band continuous observation; If n targets are irregularly distributed in range and azimuth, the satellite performs autonomous mission planning based on the number and position of n targets and generates an imaging window T for n targets. n , to ensure that the total duration of n imaging times is T n ≤2min; the satellite sends n imaging instruction orders to the satellite payload, and the payload autonomously performs n radar parameter calculations and power-on control to complete continuous multiple imaging based on irregular multi-target areas.

5. The method for constructing a long-time series observation mode of a multi-satellite network according to claim 4, characterized in that: The method relies on the satellite agile platform attitude maneuvering and the payload antenna beam electronic scanning capability to work together to complete multi-target wide-band continuous observation, including the following sub-steps: Step S3.1: Before imaging, the satellite attitude pitch angle is maneuvered to the required squint angle θ1 position for the forward squint. During imaging, the antenna distance is switched to the beam scan θ s1 ; Step S3.2: The satellite pitch maneuvers forward to the oblique angle θ2 position, and switches to the beam scan θ by the payload antenna distance s2 ; Step S3.3: Maneuver the satellite pitch angle to the required squint angle position θ3, and switch to beam scanning θ based on the payload antenna distance s3 ; Step S3.4: splicing the three echo data along the range width.

6. The method for constructing a long-time series observation mode of a multi-satellite network according to claim 1, characterized in that: The step S4 comprises: Step S4.1: Assume the orbital parameters of the previous satellite (t0, a1, e1, i1, Ω1, ω1, M1), where t0 is the epoch time, a1 is the semi-major axis, e1 is the eccentricity, i1 is the orbital inclination, Ω1 is the right ascension of the ascending node, ω1 is the argument of perigee, and M1 is the true perigee point; Step S4.2: Based on the imaging time interval Δt, calculate the orbit that overlaps with the previous satellite ground track and has a visit interval difference of Δt, satisfying: Among them, ω e is the Earth's rotation rate; Step S4.3: Calculate the imaging intervals Δt1, Δt2, ... Δt of each star according to the observed target time series n , and based on the above formula, the orbital parameters of each star are calculated.

7. The method for constructing a long-time series observation mode of a multi-satellite network according to claim 1, characterized in that: The step S5 comprises: Step S5.1: The ground operation and control system compiles and uploads the mission instructions for the first satellite Sat01. After receiving the instructions, the satellite agile platform is controlled to maintain attitude control over the ground at -T1 second in advance, the satellite data transmission and payload system are powered on at -T2 seconds in advance, the satellite performs autonomous correction of onboard imaging parameters according to real-time orbit information at -T3 seconds in advance, and the target point information of 01 satellite, imaging start and end time, and imaging wave position information are sent to Sat02 via the inter-satellite microwave communication link at -T4 seconds in advance, where T1>T2>100 seconds, T3>T4>40 seconds; at time T, the Sat01 satellite performs △t long-time series observation imaging; Step S5.2: After receiving the target and imaging parameter information sent by Sat01, Sat02 satellite also sends the target point information, imaging start and end time, and imaging wave position information of Sat02 satellite to Sat03 satellite through the inter-satellite microwave communication link according to the task timing planning of step S5.1; at time T+△t, Sat02 satellite performs △t long time series observation imaging; Step 5.3: After receiving the target and imaging parameter information sent by Sat02, Sat03 satellite also sends the target point information, imaging start and end time, and imaging wave position information of Sat03 satellite to Sat04 satellite through the inter-satellite microwave communication link according to the task timing planning of step S5.1; at time T+2△t, Sat03 satellite conducts △t long time series observation imaging.

8. A system for constructing a long-time series observation mode of a multi-satellite network, characterized in that: include: Module M1: Build the capability of single-satellite radar payload system; Module M2: For a single target observation area D1, according to the downward viewing angle θ of target D1 L Establish a satellite observation model based on single target distribution; Module M3: According to the number of target points D n and position, and establish a collaborative observation mode between the satellite agile platform and the payload antenna based on multi-target distribution; Module M4: Construction of long-term SAR observation orbits for multi-satellite networks; Module M5: Satellite autonomous control mode based on multi-satellite collaborative work.

9. The multi-satellite networked small satellite long time series observation mode construction system according to claim 8, characterized in that: The module M1 includes: designing the payload antenna to be a one-dimensional electric wave beam scan, and making the antenna beam pointing fixed in azimuth and range by coordinating the agile platform with the payload antenna electric wave scanning.

10. The multi-satellite networked small satellite long time series observation mode construction system according to claim 8, characterized in that: The module M2 includes: max Indicates the maximum scanning capability of the antenna beam. When θ L <θ max ,The satellite adopts a high-resolution imaging mode based on a long time series of level flight attitude; When θ L >θ max Through the side-swing maneuver of the satellite agile platform combined with the small-angle electronic scanning capability of the payload antenna, high-resolution imaging based on a long-term series of left and right side-view attitudes is collaboratively achieved.

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