CN107864007A - The Duo Xingduo earth stations resources co-allocation management method of facing area target - Google Patents

Abstract

The invention discloses a multi-satellite and multi-ground station resource collaborative allocation management method for regional targets, which solves the problem of multi-star and multi-ground station resource collaborative planning. The satellite unloading scheme is generated from the resource relationship diagram, the communication resource conflict-free diagram and the communication resource conflict diagram; the satellite access area target is calculated based on the target area information and the satellite ephemeris, and all possible feasible satellite unloading schemes are extracted from the satellite unloading scheme; for each Feasible satellite unloading scheme constructs weighted directed graph, traverses all weighted directed graphs, uses labeling algorithm and defined addition to find paths with high coverage and few hops to generate overall unloading scheme and inject measurement and control instructions. The invention improves the resource utilization rate and task planning efficiency, reduces the complexity of resource management, and can be used for the resource management of the earth observation satellite system.

Description

Multi-satellite multi-ground station resources collaborative allocation management method for regional targets

technical field

The invention belongs to the field of space information technology, and mainly relates to the coordinated allocation and management of resources of satellites and ground stations, in particular to a resource management method for coordinated allocation of multi-satellite and multi-ground stations oriented to coverage area targets, which can be used for the tasks of the earth observation satellite system Planning and Scheduling.

Background technique

The earth observation satellite system is an important infrastructure in my country, and its main working process mainly includes two stages of earth observation and data offloading. Specifically, the ground image information is obtained by observing various sensors equipped on the satellite, and then unloaded to the ground station. However, the contradiction between the rapidly increasing demand for observation tasks and the scarcity of resources such as observation satellites and ground stations has become increasingly prominent. In order to alleviate this contradiction, it is an objective and urgent need to study how to efficiently and reasonably arrange limited satellite and ground station resources to improve resource utilization efficiency and meet user mission requirements.

There are mainly three types of satellite observation targets: the first type is point targets, which refer to targets that can be included in one imaging, such as ports; the second type is moving targets, which means that the geographical location of targets changes with time, such as moving The third category is the regional target, which refers to the target that needs to be imaged multiple times and can only be completed by using image synthesis technology, such as: map making. Among them, a point target can be regarded as a regional target with zero area, and a moving target can be regarded as a regional target containing a moving track. Therefore, the observation of point targets and moving targets can be regarded as the observation of regional targets. If the observation area is larger than the sensor width limit of the satellite, multiple coordinated observations of a single satellite or multiple coordinated observations of multiple satellites and the coordinated reception of observation data by multiple ground stations are required. Therefore, the problem that needs to be solved is to determine which satellites are selected to observe in which observation mode (that is, the roll angle of the sensor) at what time, and which ground stations are used to receive data at what time.

In previous studies, most research work on resource allocation management considers the Earth observation or data offloading phases respectively, and focuses on the mission planning of point targets. Among them, in the article "Mission scheduling optimization of SAR satellite constellation for minimizing system responsetime", Hongrae Kim planned for the regional target, but ignored the stage of data unloading, which cannot guarantee that the complete data of the observation can be successfully unloaded to the ground station. Thereby affecting the completion efficiency of the task. Therefore, resource allocation management needs to combine the two stages of earth observation and data offloading to improve the task completion rate. However, less research work considers these two stages jointly. For example, in the article "Planning and scheduling algorithms for the COSMO-SkyMed constellation" by Nicola Bianchessi, although two stages are considered, it only focuses on the observation of point targets by the specific COSMO-SkyMed system, lacking the higher A planning method for the regional objectives of the synergy requirements. Therefore, this method cannot be applied to regional targets, thus affecting the efficient use of resources of the Earth observation satellite system. Therefore, it is necessary to design a multi-satellite multi-ground station resource collaborative allocation management method for joint earth observation and data offloading of regional targets.

Contents of the invention

The purpose of the present invention is to address the deficiencies of the existing research, and propose a multi-satellite and multi-ground station resource cooperative allocation management method for regional targets with higher efficiency and fuller resource utilization.

The present invention is a multi-satellite multi-ground station resource collaborative allocation management method for regional targets, characterized in that it includes the following steps:

(1) The ground control center obtains ground station and satellite information: the ground control center obtains the position information of the ground station and the orbit parameter information of the satellite in orbit, and calculates the access time of the satellite and the ground station.

(2) Construct the resource relationship diagram: according to the satellite access ground station resource relationship diagram G ₁ (V(G ₁ ), E(G ₁ )), the satellite access ground station resource relationship diagram G ₁ The node set of is V(G ₁ ), and the edge set is E(G ₁ ).

(3) Constructing a communication resource conflict-free graph and a communication resource conflict graph: the ground control center generates a communication resource conflict-free graph G ₂ and a communication resource conflict graph G ₄ according to the satellite access ground station resource relationship graph G ₁ .

(4) Generate satellite unloading schemes: generate all conflict-free satellite unloading schemes according to the communication resource conflict-free graph G ₂ and the communication resource conflict graph G ₄ .

(5) Constructing available satellite offloading schemes: Extract all possible available satellite offloading schemes including the target that can visit the area from conflict-free satellite offloading schemes.

(6) Constructing a weighted directed graph: The ground control center constructs a resource weighted directed graph G _directed according to the available satellite offloading scheme and the order of the data offloading time of the objects in the satellite access area.

(7) Generating an overall unloading scheme: the ground control center searches for the best possible satellite unloading scheme in the resource weighted directed graph G _directed , and finally generates an overall unloading scheme.

For each resource weighted directed subgraph Execute the labeling algorithm to search for a path with a large coverage and a small number of hops, where the addition is performed using the defined addition Define the addition operation First, a union is performed on the target area numbers. Then, sum the weights under each number, namely: Where {id _k }={id _i }∪{id _j }.

(8) Determine the optimal solution and add instructions: the ground control center selects an optimal solution from the generated overall unloading solution according to user needs, and first sends measurement and control instructions to each measurement and control ground station to perform load loading on the selected satellites according to the solution. Control, including when to turn on the sensor and how many angles to acquire data; then send data receiving instructions to each digital ground station for ground station antenna selection and data reception, and complete multi-satellite multi-ground station resource collaborative allocation management.

The invention improves the resource utilization rate of the earth observation satellite system by comprehensively considering the two stages of earth observation and data unloading.

Compared with prior art, the present invention has following advantage:

1) The present invention characterizes the correlation between satellite and ground station resource access in space and time by constructing a satellite access ground station resource relationship diagram, and provides a basis for the collaboration of the two resources. By constructing the communication resource conflict-free graph and the communication resource conflict graph, the conflict-free and conflict-free nature of satellite and ground station resource access is represented. The intermittent transmission problem of satellites and ground stations in the earth observation system is transformed into an independent set problem in the conflict graph, which greatly simplifies the complexity of the problem.

2) In the present invention, the regional objects are first rectangularized, and then different weights are assigned to the segmented regional objects. In this way, not only the coherence and importance of sub-regional targets are considered to eliminate the independence of segmentation, but also in the case of limited satellite resources, it ensures maximum resource utilization, maximum useful information and shortest response time mechanism. The invention cooperates with the side swing mode of the sensors of multiple satellites, defines a special addition that first seeks the union and then seeks the weight sum, and efficiently reflects the coverage measurement standard for the regional target, thereby ensuring the effectiveness and timeliness of task completion sex. Furthermore, the waste of resources caused by the lack of coordination among the satellites is effectively eliminated.

3) The present invention characterizes five-dimensional resources of satellite, ground station, communication, time and coverage by constructing a resource weighted directed graph, effectively decoupling the intricate relationship among multi-dimensional resources. It greatly simplifies the complexity of resource management issues in the earth observation satellite system, and provides technical support for resource management in the earth observation satellite system.

Description of drawings

Fig. 1 is the general flowchart of the realization of the present invention;

Figure 2 is a resource diagram, where Figure 2(a) is a resource relationship diagram for satellite access to ground stations, Figure 2(b) is a communication resource conflict-free diagram, Figure 2(c) is a resource diagram with conflict relationships, and Figure 2( d) is a communication resource conflict diagram;

Figure 3 is a region segmentation diagram;

Fig. 4 is the resource weighted directed subgraph constructed by the present invention;

Fig. 5 is the simulated comparative graph of the coverage rate that obtains with the present invention and random scheme;

Fig. 6 is a simulation comparison graph of the completion time of data unloading obtained by using the present invention and the random scheme.

Detailed ways

The embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Example 1

This example sets out from the earth observation satellite system to illustrate the implementation process of the present invention. Referring to Fig. 1, the earth observation satellite system used in the present invention includes a ground control center, an earth observation satellite and ground station parts. It is assumed that the earth observation satellite system consists of I satellites distributed in sun-synchronous orbits. Each earth observation satellite is equipped with H sensors with different resolutions. The roll angle range of each sensor is [-30°, 30°]. Assuming that the number of ground stations is M, and the stations are deployed locally, each ground station is equipped with n transceiver devices. The geographic location of the target area is randomly generated globally.

In previous studies, most of the research work on resource management of the earth observation satellite system only considered the earth observation or data offloading stages separately, ignoring the complex coupling of these two stages. In particular, due to the special requirements of regional goals on coverage, that is, the integrity of unloading data, the research on the coupling relationship between the two stages of regional goals is particularly important. However, so far, there has been no joint consideration of earth observation and data offloading resource collaborative allocation management methods for regional targets.

In view of this current situation, the present invention has launched a regional target-oriented multi-star multi-ground station resource collaborative allocation management research, and proposes a regional target-oriented multi-star multi-ground station resource collaborative allocation management method, see Figure 1, including the following steps :

(1) The ground control center obtains ground station and satellite information: the ground control center needs to obtain ground station information, including the longitude and latitude of the ground station, and the parameters of the transceiver equipment of the ground station. The information required for satellites includes orbital parameter information of in-orbit satellites and transceiver parameters. The satellite and ground station access times are calculated from the above information.

(2) Construct the resource relationship diagram: according to the satellite access ground station resource relationship diagram G ₁ (V(G ₁ ), E(G ₁ )), the satellite access ground station resource relationship diagram G ₁ The node set of is V(G ₁ ), and the edge set is E(G ₁ ). Satellite access ground station resource relationship diagram G ₁ depicts the availability and conflict of communication resources between satellites and ground stations, and provides technical support for the collaborative allocation and management of multi-satellite and multi-ground station resources.

(3) Constructing a communication resource conflict-free graph and a communication resource conflict graph: the ground control center generates a communication resource conflict-free graph G ₂ and a communication resource conflict graph G ₄ according to the satellite access ground station resource relationship graph G ₁ . Communication resource conflict _- free graph G2 depicts the availability of communication resources between satellites and ground stations. Communication Resource Conflicts Figure G ₄ reveals the conflicting use of communication resources between satellites and ground stations.

(4) Generate satellite unloading schemes: generate all conflict-free satellite unloading schemes according to the communication resource conflict-free graph G ₂ and the communication resource conflict graph G ₄ . Firstly, the conflict decomposition is performed _on the communication resource conflict graph G4, and then the available communication resources of the communication resource conflict _- free G2 are integrated, so that all possible combinations of available communication resources, that is, all conflict-free satellite unloading schemes can be obtained.

(5) Constructing available satellite offloading schemes: Extract all possible available satellite offloading schemes including the target that can visit the area from conflict-free satellite offloading schemes. This step is mainly to select different available satellite unloading schemes for different regional targets, which is adaptive.

(6) Constructing a weighted directed graph: The ground control center constructs a resource weighted directed graph G _directed according to the available satellite offloading scheme and the order of the data offloading time of the objects in the satellite access area. The resource weighted directed graph G _directed characterizes the resources of the earth observation satellite system from the five dimensions of satellite resources, ground station resources, communication resources, time resources and coverage. The resource-weighted directed graph G _directed corresponds to all possible available satellite offloading schemes, that is, a possible available satellite offloading scheme corresponds to one of the resource-weighted directed subgraphs which is

(7) Generating an overall unloading scheme: the ground control center searches for the best possible satellite unloading scheme in the resource weighted directed graph G _directed , and finally generates an overall unloading scheme. Specifically, for each resource weighted directed subgraph Execute the labeling algorithm to search for a path with a large coverage rate and a small number of hops, where the addition is performed using the defined addition Define the addition operation: firstly perform the union of the target area numbers, and then sum the weights under each number, namely: Where {id _k }={id _i }∪{id _j }.

(8) Determine the optimal solution and add instructions: User requirements refer to the coverage of the area target or the time to complete data unloading. The ground control center selects an optimal solution from the generated overall unloading solution according to the user's needs, and first sends the measurement and control command to each measurement and control ground station to control the load of the satellite selected above, including when to turn on the sensor for data acquisition. How many angles to put; Then, send data receiving instructions to each digital transmission ground station for ground station antenna selection and data reception (that is, data unloading), and complete multi-satellite multi-ground station resource collaborative allocation management.

The invention characterizes the relativity of satellite and ground station resource access by constructing a satellite access ground station resource relationship diagram, and provides a basis for the collaboration of the two space resources. By constructing the communication resource conflict-free graph and the communication resource conflict graph, the conflict-free and conflict-free nature of satellite and ground station resource access is represented. Based on this, the intermittent transmission problem of satellites and ground stations in the earth observation system can be transformed into the maximum independent set problem in the conflict graph, which greatly simplifies the complexity of the problem.

Example 2

The regional target-oriented multi-star multi-ground station resource collaborative allocation management method is the same as embodiment 1, and the construction resource relationship diagram described in step (2) specifically includes:

(2a) Construct the point set V(G ₁ )={S}∪{T}∪N∪S _at of the resource relationship graph G ₁ , where S is the virtual source node, T is the virtual destination node, is the set of ground station virtual points, S _at is the set of satellite nodes, It is the opportunity for the j-th satellite to visit the n-th set of transceiver equipment of the m-th ground station for the i-th time.

(2b) Construct the edge set E(G ₁ ) of the resource relationship graph G ₁ , that is, E(G ₁ )=SS∪SG∪NT∪CV, where SS is the connection between the virtual source node S and the satellite node S _i ∈ S _at Edge set, SG is the edge set from the satellite node S _i ∈ S _at to the virtual point set N of the ground station, NT is the virtual node of the ground station The edge set and CV to the virtual destination node T are the virtual node set between the ground stations and and a collection of virtual nodes within the ground station and The conflicting edge set is the conflicting edge. The satellite access ground station resource relationship diagram represents the satellite, ground station and communication three-dimensional resources, depicts the use of communication resources by satellite and ground station, and provides technical support for the collaborative allocation and management of multi-satellite and multi-ground station resources.

Example 3

The regional target-oriented multi-star multi-ground station resource cooperative allocation management method is the same as embodiment 1-2, and the ground control center described in step (3) builds a communication resource conflict-free graph and a communication resource conflict graph, specifically including:

(3a) Delete the conflict edge and the points connected to the conflict edge from the satellite access ground station resource relationship graph G ₁ to obtain the communication resource conflict-free graph G ₂ (V(G ₂ ), E(G ₂ )). Deleting the communication resource conflict-free graph G ₂ from the satellite access ground station resource relation graph G ₁ is the collection of all nodes and edges except satellite nodes, virtual source nodes and destination nodes to obtain resource graph G ₃ =G ₃ ( V(G ₃ ),E(G ₃ )).

(3b) Express the edge E(G ₃ )\CV in the resource graph G ₃ with conflict relationship as the point set V(G ₄ ) in the communication resource conflict graph G ₄ (V(G ₄ ),E(G ₄ )) ), where the edge set E(G ₄ )=CV, thus constituting the communication resource conflict graph G ₄ . The communication resource-free graph reveals the availability of communication resources by satellites and ground stations. The communication resource conflict diagram depicts the conflicting use of communication resources by satellites and ground stations. Conflict-free and conflict-free use of communication resources by satellites and ground stations is represented by constructing communication resource conflict-free graphs and communication resource conflict graphs, and the intermittent transmission problems of satellites and ground stations in the earth observation system can be transformed into conflicts The maximum independent set problem in the graph greatly simplifies the complexity of the problem.

Example 4

The multi-satellite and multi-ground station resource collaborative allocation management method for regional targets is the same as embodiment 1-3, and the ground control center described in step (4) generates a satellite unloading scheme, specifically including:

(4a) Find the maximum independent set MS={MS _i } of the communication resource conflict graph G ₄ (V(G ₄ ), E(G ₄ )), reverse the points in the maximum independent set MS={MS _i } Maps to edge sets in the resource graph _G3 with conflicting relations

(4b) Find all paths from the virtual source node S to the destination node T in the communication resource conflict _- free graph G2 by using the Dijkstra algorithm or the Bellman-Ford algorithm Extract edges from path Form an edge set: Then, the ith component in the edge set E ^MS Merge with the edge set E _feasible into a new set Finally, the total feasible output edge set is formed That is, a conflict-free satellite offloading scheme. The satellite unloading scheme can be generated by using the existing mature maximum independent set algorithm and Dijkstra algorithm, which greatly reduces the complexity of problem solving.

Example 5

The multi-satellite and multi-ground station resource cooperative allocation management method for regional targets is the same as that of embodiments 1-4, and the ground control center described in step (5) generates an available satellite unloading scheme, specifically including:

(5a) The ground control center calculates the smallest rectangular area covering the target area, and expresses it as the smallest rectangular area REC _min ={(x ₁ ,y ₁ ),(x ₂ ,y ₂ ),(x ₃ ,y ₃ ) ,(x ₄ ,y ₄ )}, where ( _xi ,y _i ) represents the latitude and longitude coordinates.

(5b) According to the requirements of the degree of approximation, divide the entire minimum rectangular area REC _min into Num sub-rectangles REC _i , and number them as id; calculate the center latitude and longitude of each sub-rectangle REC _i The sub-rectangle REC _i is given different weights according to prior knowledge: (Then each id corresponds to a weight), the coverage of the satellite sat _i on the sub-rectangle is transformed into the coverage of the center of the rectangle, and the set of coverage ids is obtained The present invention proposes a method of using the minimum rectangular area to cover the area target, specifically by dividing the rectangular area and assigning different weights to each divided sub-rectangle. This method not only considers the coherence and importance of sub-regional targets to eliminate the independence of segmentation, but also ensures the maximum resource utilization, the maximum useful information and the shortest time response in the case of limited satellite resources. mechanism. In addition, this method can also describe irregular area targets well, and has general practical value.

(5c) In the total feasible output edge set Every feasible set in Extract the set of edges containing all satellites in the satellite set TS _access (representing the satellite set that can access the target area) (i.e. available uninstall scheme).

Example 6

The multi-satellite and multi-ground station resource cooperative allocation management method for regional targets is the same as that of embodiments 1-5, the ground control center described in step (6) constructs a resource weighted directed graph G _directed , specifically including:

(6a) pairs on the edge set Each collection in are modeled as a resource-weighted directed subgraph Constitute the total resource weighted directed graph Align the timeline by time Sort in ascending order to divide, and each time point corresponds to a satellite, namely: Obtained from TS _access according to S _i in, and Indicates the start time and end time of the satellite sat _i visit area target.

(6b) According to each satellite sat _i visit area target end time Find the smallest value greater than the visit area target end time The start time of the satellite sat _i accessing the ground station That is, the start time for the j-th satellite to visit the m-th ground station to select the n-th set of transceiver equipment for the i-th visit, so as to construct a resource-weighted directed subgraph One-hop node in , and so on. corresponds to the edge set in the graph The weight of is the corresponding set The invention characterizes resources in five dimensions of satellite, ground station, communication, time and coverage by constructing a resource weighted directed graph, effectively decoupling the intricate relationship among multi-dimensional resources. It greatly simplifies the complexity of resource management issues in the earth observation satellite system, and provides technical support for resource management in the earth observation satellite system.

A more detailed and complete example is given below to further illustrate the present invention

Example 7

The regional target-oriented multi-satellite multi-ground station resource cooperative allocation management method is the same as that of Embodiments 1-6. Referring to FIG. 1, the system scenario used in the present invention includes a ground control center, an earth observation satellite and a ground station. The earth observation satellite system consists of one satellite node distributed in sun-synchronous orbit. The number of ground stations is M, and the stations are deployed locally, and each ground station is equipped with n transceiver devices. The geographic location of the target area is randomly generated globally. Visit the satellites in this area, select the appropriate resolution sensor and roll angle, and after shooting a part of the area, wait to move to the ground station coverage area for data download.

With reference to Fig. 1, the realization steps of the present invention are as follows:

Step 1. According to the known ground station information, such as the longitude and latitude of the ground station location, antenna elevation angle, etc., and the orbit parameters of the satellite in orbit, such as orbital height, inclination, ascending node right ascension, etc., the ground control center calculates the satellite and ground station access time.

(1a) Judging whether the ground station and the satellite are visible, the judging condition is: Φ>0.

If the above conditions are met, the ground station and the satellite are visible, and the satellite can unload data to the ground station; otherwise, the satellite cannot communicate with the ground station. The judgment condition symbol Φ can be calculated by the following formula:

in, is the position vector of the satellite, is the position vector of the ground station, and α is the elevation angle requirement of the antenna calibration satellite of the ground station, usually α=10°. Among them, the position vector of the satellite According to the orbit of the satellite, the position vector of the ground station Available from the ground control center database.

(1b) Record the start time t ₁ and end time t ₂ of the judgment condition Φ>0, and obtain the access duration D=t ₂ -t ₁ of the satellite and the ground station.

In step 2, the ground control center obtains relevant information of the regional target, such as the longitude and latitude of the geographic location of the regional target, and the size of the area, and constructs a satellite access ground station resource relationship map according to the access time of the satellite and the ground station.

(2a) Ground station resources are virtualized as point collections where each virtual node It is the visible time period for the jth satellite to visit the nth set of transceiver equipment of the mth ground station for the ith time. per virtual node The basis of construction is by calculating the set of access time of satellites and ground stations in The length of time for selecting the nth set of transceiver equipment for the jth satellite to visit the mth ground station for the ith time, and Select the start time and end time of the nth set of transceiver equipment for the i-th visit of the j-th satellite to the m-th ground station, respectively. Specifically, if Then build the node

(2b) Construct a virtual source node S and a virtual destination node T, and uniformly number all available satellite resources in space to obtain a satellite node set S _at ={S _i |i∈(1,2,...,I)}, Form the point set V(G ₁ )={S}∪{T}∪N∪S _at of the satellite access ground station resource relationship graph G ₁ (V(G ₁ ), E(G ₁ )). Among them, the construction of virtual source node S and virtual destination node T is for the convenience of subsequent calculation path, I represents the largest number of satellites, i represents the i-th satellite, E(G ₁ ) is the satellite access ground station resource relationship graph G ₁ The edge set of (V(G ₁ ),E(G ₁ )).

(2c) Construct the edge set E(G ₁ ) of the satellite access ground station resource relation graph G ₁ (V(G ₁ ), E(G ₁ )).

(2c1) Construct the edge set SS from the virtual source node S to the satellite node S _i ∈ S _at , construct the edge SS _i from the satellite S _i ∈ S _at and the virtual node S that have the conditions to visit the target area, and add it to the edge set SS, That is, SS=SS∪{SS _i }.

(2c2) Construct the satellite node S _i ∈ S _at to the virtual point set of the ground station The edge set SG of the satellite S _i ∈ S _at which has access to the ground station and the virtual point of the ground station add edge which is The conditions for judgment are: established, then (Denoting that j corresponds to satellite S _i ).

(2c3) Construct the virtual node of the ground station The edge set NT to the virtual destination node T, to all ground station virtual nodes Add an edge to the virtual destination node T edge set

(2c4) Construct a virtual node set between ground stations and and a collection of virtual nodes within the ground station and Conflicting edge set CV between conflicting edges, adding edges between virtual nodes with conflicts or which is or The conditions for judgment are:

Scenario 1: Ground Station Virtual Node and ground station virtual nodes length of visit and visit duration There is an intersection, that is, one of the following conditions is met: and

Scenario 2: Ground Station Virtual Node and ground station virtual nodes length of visit and visit duration There is an intersection, that is, one of the following conditions is met: and

(2d) Construct the edge set E(G ₁ ) of the satellite access ground station resource relationship graph G ₁ (V(G ₁ ), E(G ₁ )), that is, E(G ₁ )=SS∪SG∪NT∪CV.

Through step 2, as shown in Figure 2(a), through the calculated satellite and ground station access conditions, construct a resource relationship diagram for satellite access to ground stations. Point S represents the virtual source node, and T represents the virtual destination node. The three nodes in the first column after the source node represent three earth observation satellites, and the ground station is represented by a dotted line frame. The ground station virtualizes multiple nodes into two groups, and each group represents the transceiver equipment of the ground station. express. The nodes in the ellipse represent the visible time period for a certain satellite and a certain set of transceiver equipment of the local ground station to visit. Connect satellites to these virtual nodes with edges to indicate access. As long as the communication resources meet the access conditions, each satellite can be connected with these virtual nodes in its nearby ground stations or with other ground stations. The weight on the edge represents the time length of the range. It is worth emphasizing that if there is any intersection between the satellite and the access time interval of the ground station in the figure, it will be marked with a red bold line. In this way, the satellite access ground station resource relationship diagram is constructed.

Step 3, the ground control center generates a communication resource conflict graph according to the satellite access ground station resource relationship graph, and outputs all non-conflict satellite unloading schemes through conflict resolution.

(3a) Generate a communication resource conflict-free graph G ₂ (V(G ₂ ), E(G ₂ )) from the satellite access ground station resource relationship graph G ₁ (V(G ₁ ), E(G ₁ )). Access the ground station resource relationship graph G ₁ (V(G ₁ ),E(G ₁ )) from the satellite, see Figure 2(a) to delete the conflict edge and the points connected to the conflict edge, and generate a communication resource conflict-free graph G ₂ (V(G ₂ ), E(G ₂ )), see Figure 2(b), compared with Figure 2(a), it can be seen that two points and one edge are deleted in the ground station at the top, and in the ground station in the middle Three points and two edges are removed, and one point and one edge are removed in the ground station at the low end. ie for The following iterative operation is performed: E(G ₂ )=E(G ₁ )-(c,d), V(G ₂ )=V(G ₁ )-cd.

(3b) Generate resource graph G ₃ (V(G ₃ ), E(G ₃ )) with conflicting relationship from satellite access ground station resource graph G ₁ (V(G ₁ ), E(G ₁ )). Access the ground station resource relationship graph G ₁ (V(G ₁ ),E(G ₁ )) from the satellite, see Figure 2(a) to delete the communication resource conflict-free graph G ₂ (V(G ₂ ),E(G ₂ )), referring to Fig. 2(b) except satellite node, virtual source node and destination node, the set of all nodes and edges can obtain resource graph G ₃ =G ₃ (V(G ₃ ), E(G ₃ )), see Figure 2(c), that is, G ₃ (V(G ₃ ), E(G ₃ ))=G ₁ (V(G ₁ ), E(G ₁ ))-G' ₂ (V( G' ₂ ),E(G' ₂ )), where, for Update E(G' ₂ )=E(G' ₂ )∪(c,d), V(G' ₂ )=V(G ₂ )-{c}∪{d}, V(G ₃ )=V( G ₁ )-V(G' ₂ ), E(G ₃ )=E(G ₁ )-E(G' ₂ ).

(3c) Generate a communication resource conflict graph G ₄ (V(G ₄ ), E(G ₄ )) from the resource graph G ₃ (V(G ₃ ), E(G ₃ )) with the conflict relationship.

Denote the resource graph G ₃ (V(G ₃ ),E(G ₃ )) with conflict relationship, see the edge E(G ₃ )\{CV∪SS} in Figure 2(c) as a communication resource conflict graph G ₄ (V(G ₄ ), E(G ₄ )), refer to the point set V(G ₄ ) in Figure 2(d), where the edge set E(G ₄ )=CV, construct the The communication resource conflict graph G ₄ (V(G ₄ ), E(G ₄ )) is shown.

(3d) From the communication resource conflict-free graph G ₂ (V(G ₂ ), E(G ₂ )) and the communication resource conflict graph G ₄ (V(G ₄ ), E(G ₄ )) generate all possible conflict-free Satellite offloading scheme.

Find the maximum independent set MS={MS _i } of the communication resource conflict graph G ₄ (V(G ₄ ), E(G ₄ )) by using the coloring algorithm. Reversely map the points in the maximum independent set MS={MS _i } to the edge sets in the resource graph G ₃ with conflicting relations It is worth noting that: in,

Find all paths from virtual source node S to destination node T in the communication resource conflict _- free graph G2 by using Dijkstra algorithm or Bellman-Ford algorithm Extract edges from path form edge set Then, the ith component in the edge set E ^MS Merge with the edge set E _feasible into a new set Finally, the total feasible output edge set is formed For example, first refer to the communication resource conflict-free graph G ₂ in Figure 2 (b) and use the Dijkstra algorithm or Bellman-Ford algorithm to find the available satellite unloading scheme, and then refer to the communication resource conflict graph G ₄ (V in Figure 2 (d) (G ₄ ), E(G ₄ )) use the coloring algorithm to find the possible maximum available satellite offloading scheme. Finally, the above two satellite offloading schemes are integrated to generate all possible conflict-free satellite offloading schemes.

Step 4, the ground control center calculates the smallest rectangular area covering the target area according to the orbital parameters of the satellites in orbit and the geographic location information of the regional target. Then, divide the rectangular area into several sub-rectangles according to the approximation requirements, and assign different weights to each sub-matrix according to the importance. The satellite-to-sub-rectangle coverage is approximated as the coverage of the center of the sub-rectangle, and then the satellite-to-area The total weight sum of the target. And extract all possible satellite offloading schemes that contain access to the area target from the conflict-free satellite offloading schemes.

(4a) Referring to Fig. 3, the ground control center accepts the regional target task request, and first obtains the geographic location coordinates and area size of the regional target. Then calculate the smallest rectangular area for full coverage, and then segment the rectangular area. The more small rectangular areas are segmented, the higher the approximation to the area target.

The smallest rectangular area is expressed as REC _min ={(x ₁ ,y ₁ ),(x ₂ ,y ₂ ),(x ₃ ,y ₃ ),(x ₄ ,y ₄ )}, where (x _i ,y _i ) indicates latitude and longitude coordinates, and the sequence of numbering is clockwise. Divide the entire rectangular area REC _min into Num=MN sub-rectangles. Referring to Fig. 3, in this example, the target area is divided into 154 sub-rectangles. In order to simplify the calculation, set the coordinates of two adjacent points of the rectangle to the same longitude or latitude, then the rectangle area can be expressed as REC _min ={(x ₁ ,y ₁ ),(x ₂ ,y ₁ ),(x ₁ ,y ₂ ),(x ₂ ,y ₂ )}, at the same time calculate the accuracy difference and dimension difference of each point at equal intervals: The coordinates of each divided point start from the point (x ₁ , y ₁ ), and calculate how many steps are taken in the direction of longitude and latitude respectively. The longitude step is Δ _longitude , and the dimension step is Δ _latitude . x steps, y steps in the dimension direction, then the coordinates of point X are: (x ₁ +Δ _longitude x,y ₁ +Δ _latitude y). In this way, each point constitutes Num=MN sub-rectangular areas.

(4b) The coverage of the rectangular area is transformed into the coverage of the sub-rectangular area.

In order to calculate whether a sub-rectangle is covered, here, whether the center of the equivalent rectangle is covered, it is necessary to calculate the coordinates of the center of each sub-rectangle. Firstly, the rectangles are firstly numbered id∈ID sequentially from latitude to longitude, where ID={1,2,..,Num}. Then, find the location of the sub-matrix in the matrix area. Finally, pass the location of the sub-rectangle and its center coordinates Find the coordinates of the center of the sub-rectangle from the corresponding relationship, where, use To represent the corresponding relationship between the position of the sub-matrix and the latitude and longitude coordinates of its center. The location calculation of the sub-matrix can be done through the following relationship:

id mod N = x ^mod , y ^rem = id-x ^mod N.

If ^yrem = 0, then Otherwise y ^rem ≠ 0, then The center coordinates of each sub-rectangle are calculated by taking the center coordinates of the first sub-matrix REC ₁ as a reference, and calculating the relative position, that is, how many steps to the longitude and latitude. The center coordinates of the sub-matrix REC ₁ are: For sub-matrix REC _i , if satisfies longitude Then the longitude coordinates of the matrix center are if satisfied Then the longitude coordinates of the matrix center are If the latitude satisfies Then the matrix center dimension coordinates are Then the longitude coordinates of the matrix center are Then get the coordinates of the center of the matrix

(4c) Different weights are assigned to different sub-matrixes REC _i according to prior knowledge: in, The center coordinates are submatrix REC _i . use Indicates that the sub-matrix REC _i is numbered as id and the corresponding weight is w. For example, referring to FIG. 3 , the edge sub-rectangle of the rectangle that does not cover the relevant information of the area target can be given a weight of 0, and other information covered with the area target can be given different weights based on its corresponding importance.

(4d) Record the set of ids of all sub-rectangles REC _i covered by each satellite sat _i .

The conditions for judging whether the satellite sat _i can cover the rectangle REC _i numbered id when it meets the resolution requirements are:

in, is the center coordinate of matrix REC _i To the sub-satellite point coordinates of satellite sat _i at time t distance, h _i is the orbital height of satellite sat _i , is the sensor depression angle of satellite sat _i is the maximum roll angle of satellite sat _i , m is the mode number, and γ is the roll angle of each mode.

If the condition is true, record the id set of satellite sat _i covering the area target in the planning period: And record the start time, end time and satellite number three-dimensional array of the target in the visited area if Then TS _access =TS _access ∪{Sat _i }, where TS _access represents a set of satellites that can access the target area.

(4e) For the total feasible output edge set Every feasible set in Extract the edges containing all satellites in the satellite set TS _access to form a set but For example, consider an Earth observation satellite system with three Earth observation satellites. Two of the earth observation satellites use different sensor modes to obtain different regional target information, and one earth observation satellite does not have the information to observe regional targets. The present invention selects a feasible unloading scheme of two earth observation satellites capable of visiting regional targets from the feasible unloading schemes of satellites. And by coordinating the sensors of the two satellites to avoid repeated coverage of the target area by the two satellites, the satellite resources and communication resources are saved, and the target image data acquired by it can be offloaded to the The ground station can complete observation tasks accurately and efficiently.

Step 5, the ground control center constructs a resource weighted directed graph according to the orbital parameters of the satellites in orbit and the geographical location information of the regional target.

For each collection in fE ^Output Model the problem as a weighted directed subgraph Construct a virtual source node S and a virtual destination node T, see Figure 2. in, Align the timeline by time Sort in ascending order to divide, and each time point corresponds to a satellite, namely: Obtained from TS _access according to S _i According to each satellite sat _i visit area target end time Find the smallest value greater than the visit area target end time The start time of the satellite sat _i accessing the ground station That is, the start time for the j-th satellite to visit the m-th ground station to select the n-th set of transceiver equipment for the i-th visit, so as to construct a resource-weighted directed subgraph One-hop node in , and so on. corresponds to the edge set in the graph The weight of is the corresponding set

Referring to Fig. 4, Fig. 4 is a resource weighted directed subgraph, in which three boxes are listed. The first box contains six red nodes, which are divided into two groups and numbered k1 and k2 respectively. There are three dots in the first group representing three different sensor modes: Mode 1, Mode 2, and Mode 3. Each pattern represents a different roll angle for the sensors on a satellite. For example: CBERS-1 satellite sensor has a roll range of ±32°, if each pattern is rotated by 2°, there are 32 patterns in total. Number k1 represents the first visit to the target area, and similarly, number k2 represents the second visit to the target area. The weights of the edges in the weighted directed graph of the resource weighted directed graph of the target area are obtained by the satellite's first visit to the regional target in different modes, and the second visit is carried out in the same way. But the addition of weights must be calculated according to the addition defined above. Moreover, a box corresponds to a time point, as shown in FIG. 4 , the time point corresponding to the first box is t1, and this time point corresponds to the time when the satellite unloads data to the ground station. Then, arrange these time points in ascending order, and find the path that meets the mission requirements with the largest weighted sum and the corresponding number of hops, that is, the optimal combination of satellites and the combination of satellite sensor roll angles.

In step 6, the ground control center searches for the best feasible satellite unloading scheme in the conflict-free satellite unloading scheme according to the satellite resource scheme of survival in the weighted directed graph to generate an overall scheme.

For each rule directed graph with weights attached Executes the notational algorithm, where addition is performed using the defined addition The addition operation is defined as follows: First, the target area numbers are combined. Then, sum the weights under each number: Among them, {id _k }={id _i }∪{id _j }.

Step 7. The ground control center selects an optimal plan from the generated overall plan according to the user's needs, and sends the measurement and control instructions to each measurement and control ground station respectively. Station antenna selection and data reception.

In the present invention, the ground control center calculates the time for the satellite to visit the ground station according to the ground station information (including position, etc.) and the satellite ephemeris; constructs a resource relationship diagram through the calculated time, and generates a communication resource conflict diagram, and outputs all Conflict-free overall satellite unloading scheme; calculate the satellite access target area situation according to the target area information (including location, etc.) and satellite ephemeris, and construct a conflict-free satellite unloading scheme for each type of conflict-free satellite unloading scheme through a series of operations such as rectangularizing the area target Weighted directed graph; the ground control center traverses all weighted directed graphs, uses labeling algorithm and defined addition to find out the path with large coverage and small path length to generate the optimal solution. According to the optimal plan, the ground control center sends measurement and control commands to the above-mentioned selected satellites for load control and each data transmission ground station sends data reception commands to the ground station antenna selection and data reception according to the optimal plan. The invention uses a graph model to characterize the intermittency and correlation of resources in the earth observation satellite system, thereby reducing the complexity of resource management.

Technical effect of the present invention is described again below by emulation

Example 8

The multi-satellite multi-ground station resource cooperative allocation management method for regional targets is the same as that in Embodiments 1-7.

Simulation conditions

In the simulation scenario, the latitude and longitude coordinates of the regional target are randomly generated from the longitude range [0°, 120°] and the latitude range [-30°, 60°] respectively. Considering two kinds of square area targets whose side lengths are 2° and 4° respectively, their areas are 4 and 16 respectively. Four Earth observation satellites distributed in sun-synchronous orbits are considered, namely CBERS-1, FY1, Worldview3 and QuikBird, and their orbital inclinations are 98.5°, 98.87°, 98.48° and 98.00° respectively. Wherein, the roll angle range of the sensor on each satellite is [-30°, 30°]. The ground stations are Kashi, Sanya and Miyun respectively, and their latitude and longitude are (76°, 39.5°), (109.5°, 18°), (116°, 40°).

Simulation content and results

What needs to be pointed out is that there is no joint consideration of earth observation and data offloading in the existing regional target-oriented resource allocation management. Therefore, in the data offloading stage, it is considered to randomly select some non-conflicting communication resources for data offloading, that is, a random scheme, as a comparison scheme with the present invention.

Simulation 1, using the method of the present invention and the random scheme to simulate and compare the coverage of the regional target, the result is that the cooperative communication resource allocation management of the present invention has effectively improved the coverage of the regional target. The simulation comparison curve of the coverage obtained by the invention and the random scheme.

It can be seen from FIG. 5 that, as the dimension of the regional target changes, the present invention compares the coverage of the target area under two different regional targets and the comparison scheme. For the case where the area of the target area is 4, the present invention significantly improves the coverage within the dimension range [-30°, -18°]. For the case where the area of the target area is 16, the coverage of the present invention is significantly improved in the dimension range [-30°, -10°] and the dimension range [20°, 35°] respectively. In addition, satellite resources, ground station resources and communication resources in the Earth observation satellite system are scarce and expensive. Therefore, the present invention can utilize the minimum resource cost to achieve the maximum coverage of the target area.

Example 9

The multi-star and multi-ground station resource cooperative allocation management method for regional targets is the same as that of Embodiment 1-7, and the simulation conditions and content are the same as those of Embodiment 1-8.

Simulation 2, using the method of the present invention and the random scheme to simulate and compare the completion time of image data unloading of regional objects, the result is that the collaborative communication resource allocation management of the present invention effectively reduces the completion time of image data unloading of regional objects, see Figure 6, Fig. 6 is a simulation comparison graph of the completion time of data unloading obtained by using the present invention and the random scheme.

It can be seen from FIG. 6 that as the dimension of the regional object changes, the present invention compares the completion time of unloading the target image data and the comparison schemes under two different area objects. For the case where the area of the target area is 4, the present invention significantly reduces the completion time of target image data unloading within the dimension range [-30°, 60°]. For the case where the area of the target area is 16, the completion time of target image data unloading in the present invention is significantly reduced in the dimension range [-30°, 60°], except in individual dimensions, such as -25°, -20°, - 5°, 0°. Therefore, the present invention can effectively reduce the completion time of unloading the image data of the area target. Especially in emergency application scenarios, the present invention can improve the ability to respond to emergency events.

To sum up, the multi-satellite multi-ground station resource collaborative allocation management method disclosed by the present invention solves the problem of multi-star multi-ground station resource collaborative planning. The realization process is as follows: the ground control center obtains the Construct resource relationship diagram, communication resource conflict-free diagram and communication resource conflict diagram respectively with satellite information to generate satellite offloading plan; calculate satellite visit area target based on target area information and satellite ephemeris, and extract all possible feasible satellite offloading schemes from satellite offloading plan Scheme: Construct a weighted directed graph for each feasible satellite unloading scheme, traverse all weighted directed graphs, use labeling algorithm and defined addition to find out the path with high coverage and few hops to generate an overall unloading scheme and inject measurement and control instructions. The invention uses the graph model to characterize the intermittence and correlation of resources in the earth observation satellite system, improves resource utilization and task planning efficiency, reduces the complexity of resource management, and can be used for resource management of the earth observation satellite system .

Claims (6)

1. A multi-satellite multi-ground station resource collaborative allocation management method facing to regional targets is characterized by comprising the following steps:

(1) the ground control center acquires information of a ground station and a satellite: the ground control center acquires the position information of the ground station and the orbit parameter information of the in-orbit satellite and calculates the access time of the satellite and the ground station;

(2) constructing a resource relation graph: constructing a satellite access ground station resource relation graph G according to the time of satellite access ground station₁(V(G₁),E(G₁) Therein, a satelliteAccessing a ground station resource relationship graph G₁Is V (G)₁) The set of edges is E (G)₁)；

(3) Constructing a communication resource conflict-free map and a communication resource conflict map: the ground control center accesses the ground station resource relation graph G according to the satellite₁Generating a communication resource collision free map G₂And communication resource conflict graph G₄；

(4) And (3) generating a satellite unloading scheme: conflict free graph G from communication resources₂And communication resource conflict graph G₄Generating all conflict-free satellite unloading schemes;

(5) constructing an available satellite unloading scheme: extracting all possible available satellite unloading schemes containing targets with access to the region from the conflict-free satellite unloading schemes;

(6) constructing a weighted directed graph: the ground control center constructs a resource weighted directed graph G according to the sequence of the return time of the target to be data of the satellite access area according to the available satellite unloading scheme_directed；

(7) Generating an overall unloading scheme: ground control center in resource weighted directed graph G_directedSearching for the best satellite feasible unloading scheme, and finally generating a total unloading scheme;

weighting directed subgraphs for each resourcePerforming a label algorithm to search for paths with large coverage and short hop count, wherein the addition uses a defined addition to operateDefining an addition operation: firstly, carrying out union set on the area numbers; then, summing the weights under each number, that is:wherein { id_k}＝{id_i}∪{id_j}；

(8) Determining an optimal scheme and annotating instructions: the ground control center selects an optimal scheme from the generated total unloading scheme according to the user requirements, and firstly sends a measurement and control instruction to each measurement and control ground station according to the scheme to inject the selected satellite for load control, including when to turn on a sensor for data acquisition and how many angles to swing laterally; and then sending a data receiving instruction to each data transmission ground station to perform antenna selection and data reception of the ground station, and completing multi-satellite multi-ground-station resource collaborative allocation management.

2. The area-target-oriented multi-satellite multi-ground-station resource collaborative allocation management method according to claim 1, wherein the constructing of the resource relationship diagram in the step (2) specifically includes:

(2a) building a resource relationship graph G₁Set of points V (G)₁)＝{S}∪{T}∪N∪S_atWherein S is a virtual source node, T is a virtual destination node,set of virtual points for ground stations, S_atFor the set of satellite nodes to be considered,an opportunity for the jth satellite to access the nth set of transceiver equipment of the mth ground station for the ith time;

(2b) building a resource relationship graph G₁Edge set E (G)₁) I.e. E (G)₁) -SS { (U.S.G { (U.T {) CV, wherein SS is the virtual source node S to the satellite node S_i∈S_atOf the set of edges, SG, to construct a satellite node S_i∈S_atTo the set of virtual points N of the ground station, NT being the virtual node for constructing the ground stationThe set of edges to the virtual destination node T and the CV are virtual node sets between the constructed ground stationsAndand virtual node set within ground stationAndthe sets of edges between which there is a conflict are conflict edges.

3. The area-target-oriented multi-satellite multi-ground-station resource collaborative allocation management method according to claim 1, wherein the ground control center in step (3) constructs a communication resource conflict-free map and a communication resource conflict map, specifically comprising:

(3a) accessing ground station resource relationship graph G from satellite₁Deleting the conflict edge and the point connected with the conflict edge to obtain the communication resource conflict-free graph G₂(V(G₂),E(G₂) Access from the satellite to the ground station resource relationship graph G)₁Medium erasure communication resource collision free map G₂The resource graph G with the conflict relationship is obtained by the aggregation of all nodes and edges except the satellite node, the virtual source node and the destination node₃＝G₃(V(G₃),E(G₃))；

(3b) Resource graph G with conflict relationship₃Middle edge E (G)₃) The CV representation is a communication resource conflict graph G₄(V(G₄),E(G₄) Set of points V (G)₄) Wherein, the edge set E (G)₄) Forming a communication resource conflict graph G₄。

4. The area-target-oriented multi-satellite multi-ground-station resource collaborative allocation management method according to claim 1, wherein the ground control center in step (4) generates a satellite unloading scheme, specifically including:

(4a) finding a communication resource conflict graph G₄(V(G₄),E(G₄) MS ═ MS) of the maximum independent set_iGet the maximum independent set MS ═ MS_iMapping points in the map with conflict relation resource map G in reverse direction₃Edge set in (1)

(4b) Conflict-free map G at communication resource by using Dijkstra algorithm or Bellman-Ford algorithm₂Finds all paths from the virtual source node S to the destination node TExtracting edges from pathAnd (3) forming an edge set:then, set the edge E^MSThe ith component inAnd edge set E_feasibleAre merged into a new setFinally, forming a total feasible output edge set

5. The area-target-oriented multi-satellite multi-ground-station resource collaborative allocation management method according to claim 1, wherein the ground control center in step (5) generates an available satellite offloading scheme, specifically including:

(5a) the ground control center calculates the minimum rectangular area coverage target area and expresses the minimum rectangular area REC_min＝{(x₁,y₁),(x₂,y₂),(x₃,y₃),(x₄,y₄) Wherein (x)_i,y_i) Representing longitude and latitude coordinates;

(5b) according to the requirement of the approximation degree, dividing the whole minimum rectangular area REC_minDivided into Num sub-rectangles REC_iAnd numbered as id; calculating each sub-rectangle REC_iCenter longitude and latitude ofSub-rectangle REC_iDifferent weights are given according to prior knowledge:(each id corresponds to a weight), satellite sat_iThe coverage of the sub-rectangles is converted into the coverage of the rectangle center, and a coverage id set is obtained

(5c) Set of edges at total feasible outputEach feasible set ofExtracting a set TS containing satellites_accessSet of edges of all satellites in the system

6. The area-target-oriented multi-satellite multi-ground-station resource collaborative allocation management method according to claim 1, wherein the ground control center in step (6) constructs a resource weighted directed graph G_directedThe method specifically comprises the following steps:

(6a) to edge setEach set ofAre all modeled as a resource weighted directed subgraphConstructing an overall resource weighted directed graphTime axis is expressed in timeAscending sorting and dividing, wherein each time point corresponds to a satellite, namely:according to S_iFrom TS_accessTo obtainWherein,andindicating satellite sat_iA start time and an end time of the access area target;

(6b) according to the satellite sat at a time_iTarget end time of access areaFinding a minimum target end time greater than the access areaOf the satellite sat_iAt the beginning of the visit to the ground stationWorkshopNamely, the ith satellite visits the mth ground station for the ith time to select the start time of the nth set of transceiver equipment, and thus a resource weighted directed subgraph is constructedOne-hop node in the graph, and so on, corresponding to the edge set in the graphIs the corresponding set