Heterogeneous spacecraft cluster communication network generation and topological optimization method

Abstract

The invention discloses a heterogeneous spacecraft cluster communication network generation and topological optimization method, which belongs to the technical field of spacecraft communication, and comprises the following steps: dividing spacecrafts in a cluster according to function types, including a pilot spacecraft, a communication spacecraft and a task execution spacecraft, defining different communication capacities (maximum connectivity) for spacecrafts with different functions, and defining the maximum communication hop count (maximum communication radius) of a cluster; the method comprises the following steps: taking a pilot spacecraft as an initial node generated by a cluster communication network, generating a minimum spanning tree of the cluster communication network based on a Prim algorithm under the constraint of degree and radius, and placing a communication spacecraft at the front end of a communication link based on a capacity priority criterion to complete cluster communication topology initialization; the algorithm is embedded into a cluster operation process to realize real-time topological optimization of the cluster operation process; when some spacecrafts in the cluster fail, the algorithm is forcibly called to reconstruct the cluster topology, so that the stability of a cluster communication network is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of spacecraft communication, and particularly relates to a method for generating and topologically optimizing a heterogeneous spacecraft cluster communication network. Background Art

[0002] With the continuous development of space technology, the diversity and complexity of on-orbit services are also increasing day by day, including aspects such as space target monitoring, on-orbit takeover, and on-orbit maintenance. Since the member spacecraft in a spacecraft cluster can carry different payloads and have the characteristics of wireless communication and resource sharing, different requirements of space missions can be met through the mutual cooperation among member spacecraft. However, in addition to the spacecraft mainly responsible for communication in the cluster, the communication devices carried by the remaining spacecraft are relatively simple and the communication capabilities are limited, which will lead to certain communication constraints in the spacecraft cluster network. And in a wireless network, communication delay is inevitable, all of which will affect the stability of the system. In addition, during the space mission process, if there are some spacecraft failures or large changes in relative positions in the cluster, the original communication topology structure will be damaged or inapplicable to the changed cluster configuration.

[0003] A minimum spanning tree is to find a tree that contains all vertices in a weighted connected graph, and the sum of the edge weights of the tree is the smallest. There are usually two algorithms to solve the minimum spanning tree problem: Kruskal algorithm and Prim algorithm. This connection strategy is very consistent with the goal of communication connection in a space cluster, so this method is widely used in the generation design of a space cluster communication network. During the execution of a space mission by a heterogeneous spacecraft cluster, not only the safe and stable operation of the cluster needs to be maintained, but also the efficient information transfer and sharing among member spacecraft need to be considered. Since the functions of each member spacecraft in the cluster are different and the communication capabilities are not the same, and communication delay is inevitable, the communication generation strategy based solely on the traditional minimum spanning tree algorithm cannot meet the requirements of information transfer in space missions. At the same time, when some member spacecraft in the cluster fail, the communication topology of the cluster is damaged, and it is necessary to perform topology reconstruction on the overall communication network of the cluster to ensure the normal information transfer of the cluster to meet the stable and efficient mission performance. To solve this problem, it is necessary to propose a method for generating and topologically optimizing a heterogeneous spacecraft cluster communication network. Summary of the Invention

[0004] Aiming at the above deficiencies in the prior art, a method for generating and topologically optimizing a heterogeneous spacecraft cluster communication network provided by the present invention solves problems such as limited communication capacity, long communication delay, low communication resource utilization rate, and poor network stability of a heterogeneous spacecraft cluster, and can realize various functional requirements such as fast information transfer, efficient sharing, real-time topology optimization, and fast topology reconstruction of the cluster.

[0005] To achieve the above-mentioned invention objectives, the technical solution adopted by the present invention is as follows: A method for generating and topologically optimizing a heterogeneous spacecraft cluster communication network, comprising the following steps:

[0006] S1. Establish a LVLH coordinate system with the leading spacecraft in the heterogeneous spacecraft cluster as the center, determine the initial positions and initial velocities of each member spacecraft, and realize the initialization of the cluster state;

[0007] S2. Divide the spacecraft in the cluster according to their functions, define the communication capacity of each spacecraft, and at the same time define the maximum communication hop count of the cluster;

[0008] S3. Take the leading spacecraft as the initial node of the cluster communication, consider the constraints of degree and radius, and generate a minimum spanning tree of the communication network based on the Prim algorithm and the communication capacity priority criterion to realize the initialization of the cluster topology;

[0009] S4. Embed the algorithm into the space operation process of the cluster, update the communication topology connection mode according to the change of the relative distance between member spacecraft, and realize the real-time topology optimization of the cluster;

[0010] S5. When some spacecraft in the cluster fail, forcefully call the algorithm to regenerate a new communication topology and realize the reconstruction of the cluster communication topology.

[0011] The beneficial effects of the present invention are as follows: By establishing a relative motion model of the cluster with the leading spacecraft as the center, the present invention establishes a cluster communication network according to the initial states and relative positions of each spacecraft. Considering that the communication capabilities of spacecraft with different functions are different and there is communication delay in the cluster, a minimum spanning tree algorithm with degree and radius constraints is designed based on the Prim algorithm, and based on the communication capacity priority criterion, spacecraft with stronger communication capabilities are placed at the front end of the communication link to realize the efficient utilization of communication resources and maximize the efficiency of information sharing and transmission. Embed this algorithm into the cluster operation process, regularly feedback the relative positions of each spacecraft inside the cluster, and on this basis, update the topology connection mode in real time. After some spacecraft fail, the topology can be quickly reconstructed to establish a new communication network to ensure the stability of cluster communication and the safety of mission execution.

[0012] Further, the expression of the relative motion equation of the spacecraft in the LVLH coordinate system in step S1 is as follows:

[0013]

[0014] where x i , y i , z i represent the components of the position vector of the i-th member spacecraft, respectively represent the components of the corresponding velocity vector and acceleration vector, μ represents the gravitational coefficient, and m i represents the mass of the i-th member spacecraft, and r f represents the modulus of the position vector between the leader spacecraft and the geocenter, and ω represents the orbital angular velocity of the leader spacecraft. represents the components of the control force in the three coordinate axis directions. represents the disturbance differences in the three coordinate axis directions between the leader spacecraft and the i-th member spacecraft. The disturbance terms involve J 2 term perturbation, atmospheric drag, solar radiation pressure, etc.

[0015] When the spacecraft operates in the low Earth orbit, the J 2 term perturbation is the main disturbance factor affecting the stable motion of the spacecraft. Here, the equation of the J 2 term perturbation received by the spacecraft in the LVLH coordinate system is expressed as

[0016]

[0017] Here, J 2 = 0.0010826 is the second-order zonal harmonic coefficient.

[0018] In addition to the J 2 term perturbation, the atmospheric drag perturbation is another important perturbation factor affecting the operation of low Earth orbit spacecraft, and can be expressed as

[0019]

[0020] Among them, C D represents the drag coefficient, A represents the force-bearing area, ρ represents the atmospheric density, and v reli represents the velocity vector of the i-th member spacecraft relative to the atmosphere, and can be expressed as

[0021]

[0022] Among them, R i represents the position vector of the i-th member spacecraft, represents the angular velocity of the Earth's rotation, and its direction is along the z-axis direction.

[0023] The beneficial effect of the above further solution is that: Under the influence of considering the J 2 term perturbation, atmospheric drag perturbation, etc. in the low Earth orbit, a relative motion dynamics model centered on the leader spacecraft in the space cluster is established, laying a foundation for the high-precision operation of the spacecraft cluster in orbit.

[0024] Furthermore, in an embodiment of the present invention, in step S2, the spacecrafts in the cluster are divided according to their functions, the communication capacity of each spacecraft is defined, and at the same time, the maximum communication hop count of the cluster is defined. For heterogeneous spacecraft clusters, according to different requirements of space missions, the member spacecrafts can be roughly divided into three categories according to their respective functions:

[0025] (1) Pilot spacecraft

[0026] The pilot spacecraft is the core of the entire spacecraft cluster and the brain of the cluster. It is responsible for receiving instructions sent from the ground and transmitting them to other spacecrafts through inter-satellite links. At the same time, it integrates and processes the information fed back by other spacecrafts and sends it back to the ground.

[0027] (2) Communication spacecraft

[0028] The communication spacecraft plays an important role in the generation of the communication network and the information transmission process of the cluster. It is equipped with a large communication payload capacity and can establish communication connections with multiple spacecrafts in the cluster. It is a key link in the information transmission of the cluster.

[0029] (3) Mission execution spacecraft

[0030] The mission execution spacecraft includes spacecrafts with various mission functions such as observation, docking, fuel replenishment, and capture. It is responsible for the specific execution of various space missions. During the execution process, it often needs to form corresponding configurations according to mission requirements, execute mission instructions, and feedback various information.

[0031] On this basis, according to the functions of different spacecrafts, the communication capacity of various spacecrafts is defined. Generally, the member spacecrafts are sorted according to the communication capacity as follows: Communication spacecraft > Pilot spacecraft > Mission execution spacecraft. At the same time, to reduce communication latency, the maximum communication hop count of the cluster communication network is defined according to the number and scale of the cluster members, that is, the maximum number of spacecrafts included in a single communication link, providing a basis for subsequent topology generation and optimization.

[0032] The beneficial effects of the above further solution are: By constraining the communication capacity and communication hop count of the member spacecrafts according to the characteristics of the heterogeneous cluster, the complexity and communication latency of the communication connections between the cluster members can be effectively reduced. Combining the balance and connectivity of the network, the member spacecrafts can selectively form communication topologies with other spacecrafts within their communication range, making the communication network distribution of the entire cluster more reasonable and improving the overall operation efficiency of the cluster.

[0033] Furthermore, step S3 includes the following steps:

[0034] S301. Use the leading spacecraft as the initial communication node of the cluster network, and generate the minimum spanning tree of the cluster communication network with degree and radius constraints based on the Prim algorithm;

[0035] S302. According to the communication capacity priority criterion, design the communication link to preferentially connect the spacecraft with larger communication capacity, so as to realize the efficient utilization of communication resources.

[0036] The beneficial effects of the above further scheme are as follows: Considering the constraints of spacecraft communication capacity and communication hops, the Prim algorithm will, according to the relative positions of spacecraft at the current moment, find the two spacecraft with the shortest relative distance to establish a communication connection to realize the rapid generation of the cluster communication network; while the communication capacity priority criterion will add weights to the difference in communication capacity between the two connected spacecraft on the basis of the Prim algorithm, thereby optimizing the edge weight calculation method, placing the spacecraft with stronger communication capabilities at the front end of the communication link, realizing the efficient utilization of communication resources, and ensuring the rationality of the cluster communication network.

[0037] Furthermore, the specific implementation process of the step S301 of generating the minimum spanning tree of the cluster communication network with degree and radius constraints based on the Prim algorithm is as follows:

[0038] First, determine the weighted undirected graph G=(V, E, w) of the spacecraft cluster communication topology, where V is the vertex set, and v i is the i-th element in the vertex set, and also represents the spacecraft with serial number i in the cluster, and the vertex corresponding to the leading spacecraft is used as the root vertex. d(v i ) is the degree of the vertex vi, and dc(vi) is the degree constraint of the vertex vi. (v i , v j ) represents the edge between the i-th spacecraft and the j-th spacecraft., wij is the weight on the edge (v i , v j ), W = Σw ij , (v i , v j ) ∈ E m , where Em is a subset of E. T is the spanning tree centered on the root vertex, and P(v i ) is the path from v s to v i , where v i ∈V, v i ≠v s . Define Q(P(v i )) as the sum of the number of edges on the path P(v i ), r a (T) = maxQ(P(v i )) is the maximum distance from the root node to other nodes, also known as the radius of the tree T, and finally define rc is the radius constraint. Then, the problem of finding the minimum spanning tree T of the weighted undirected graph G=(V, E, w) with degree and radius constraints * can be transformed into the following optimization problem

[0039] T * = minW(T)

[0040]

[0041] The beneficial effect of the above further solution is that the present invention realizes the rapid generation of the trunking communication network through the above process.

[0042] Furthermore, in step S302, according to the communication capacity priority criterion, the communication link preferentially connects the spacecraft with larger communication capacity. The specific implementation process is as follows:

[0043] For the weighted undirected graph G=(V, E, w) of the spacecraft cluster communication topology, where V is the vertex set, v i is the i-th element in the vertex set, and also represents the spacecraft with serial number i in the cluster. (v i , v j ) represents the edge between the i-th spacecraft and the j-th spacecraft, and wij is the weight on the edge (v i , v j ). According to the communication capacity priority criterion, the calculation method of the weight on the edge is improved, and the weight calculation formula for the edge (v i , v j ) is defined as:

[0044]

[0045] Among them, represents the three components of the position of the i-th spacecraft at the current moment, σ is the communication capacity influence factor, and σ < 0, W = Σw ij , (v i , v j ) ∈ E m , where Em is a subset of E. T is the spanning tree centered on the root vertex, and P(v i ) is the path from v s to v i , where v i ∈V, v i ≠v s . Define Q(P(v i )) as the sum of the number of edges on the path P(v i ), and r a (T) = maxQ(P(v i)) is the maximum distance from the root node to other nodes, also known as the radius of the tree T. Finally, rc is defined as the radius constraint. Then, according to the communication capacity priority criterion, finding the minimum spanning tree T of the weighted undirected graph G=(V, E, w) with degree and radius constraints * The problem can be transformed into the following optimization problem

[0046] T * = minW(T)

[0047]

[0048] The specific steps of the algorithm are as follows:

[0049] (1) Define the selected vertex set S = {v s}), where vs represents the leading spacecraft, and Based on vertex vi, define two variables. The first variable is the remaining degree r s (v i ) = d c (v i ), and the second variable is the distance to the root vertex Nh(v i ) = 0. Define the edge set T e of the minimum spanning tree with degree and radius constraints.

[0050] (2) Select all the edges in the edge set ε of the weighted undirected graph G=(V, ε, ω) that have a connection relationship with the set S. Calculate the weights of each edge according to the weight calculation formula, and sort these edges in ascending order of weight and store them in the set ε e .

[0051] (3) Starting from the first edge in the set ε e , search for the corresponding starting vertex v i and ending vertex v j according to the connection relationship, where v i satisfies r s (v i ) > 0 and N h (v i ) < r c , v j satisfies r s (v j ) > 0, and add the selected edge (v i , v j ) to the set T e .

[0052] (4) Add the expanded vertex v j to the set S, and update the remaining degrees of vertices v i and v j , that is, r s (vi ) = r s (v i ) - 1, r s (v j ) = r s (v j ) - 1. Update the radius of vertex v j , that is, N h (v j ) = N h (v i ) + 1.

[0053] (5) Based on the remaining degrees of each vertex after the update, recalculate the weights of each edge according to the weight calculation formula;

[0054] (6) Judge the vertex v i in set S. If r s (v i ) = 0, or N h (v i ) = r c , then delete the vertex v i from set S;

[0055] (7) Calculate the total number of edges in set T e . If the number of edges is less than n - 1, return to step (2) to continue the calculation; if T e already contains n - 1 edges, the algorithm ends, and T e is the required minimum spanning tree that satisfies the degree sum and radius constraints and gives priority to capacity.

[0056] The beneficial effect of the above further solution is: Through the above steps, the present invention realizes the reasonable layout of the communication topology of the spacecraft cluster and the efficient utilization of communication resources.

[0057] Furthermore, in step S4, the algorithm is embedded in the space operation process of the cluster, and the communication topology connection mode is updated according to the change of the relative distance between member spacecraft. It is set to re - obtain the relative position information of member spacecraft every 10s, and update the cluster communication network according to this information to achieve real - time topology optimization of the cluster.

[0058] The beneficial effect of the above further solution is: Through the above process, the present invention realizes the effective utilization of the designed algorithm in the space operation process of the spacecraft cluster.

[0059] Furthermore, when some spacecraft in the cluster fail, in step S5, the algorithm is forcibly called to regenerate a new communication topology to achieve the reconstruction of the cluster communication topology. In a cluster with m spacecraft, the relative distance matrix between each spacecraft in the cluster is defined as:

[0060]

[0061] Among them, l ij represents the distance between the i-th and j-th member spacecrafts in the cluster. The main diagonal indicates that the distance between each spacecraft and itself is 0;

[0062] Define the serial number of the failed spacecraft in the cluster as c. Then, no other spacecraft in the cluster can establish a communication connection with it. Therefore, the relative distances between the failed spacecraft and other spacecrafts are no longer calculated and are all recorded as 0, obtaining the relative distance matrix as follows:

[0063]

[0064] To enable the effective operation of the algorithm, all elements with a value of 0 in matrix A are set to Inf. Then, the algorithm will not consider the edges related to the failed spacecraft during the weight comparison process. Based on this, through the minimum spanning tree algorithm described in step S3, the communication links of other spacecrafts in the cluster except the failed spacecraft can be obtained, and finally the topological reconstruction of the entire spacecraft cluster is realized.

[0065] The beneficial effects of the above further solution are as follows: timely obtain the status information of the failed spacecraft, update the relative position matrix information of the cluster members, use the designed algorithm to perform the communication topology reconstruction of the spacecraft cluster, ensure the communication stability of the cluster to the greatest extent, reduce the risk of the cluster topology being forced to be damaged, and improve the safety and mission execution efficiency of the member spacecrafts. Brief Description of the Drawings

[0066] Figure 1 is the flowchart of the method of the present invention;

[0067] Figure 2 is the schematic diagram of the implementation process of the algorithm designed by the present invention. Detailed Embodiment

[0068] The following describes the detailed embodiment of the present invention to facilitate those skilled in the art of the present technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the detailed embodiment. For those of ordinary skill in the art of the present technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

[0069] As Figure 1 shown, the method includes the following steps:

[0070] In step S1, an LVLH coordinate system is established with the leader spacecraft as the center in the heterogeneous spacecraft cluster, considering the near-earth orbit J 2Space disturbance factors such as item perturbation and atmospheric drag perturbation are considered, and a relative motion dynamics model of spacecraft clusters is established based on the relative motion equation of elliptical orbits (TH equation). Further, the initial position and initial velocity of the leader spacecraft in the geocentric inertial coordinate system, as well as the relative positions and relative velocities of each member spacecraft in the LVLH coordinate system, are given to initialize the cluster state information and provide a basis for subsequent cluster space operations.

[0071] In step S2, the spacecraft in the cluster are divided according to their functions, the communication capacity of each spacecraft is defined, and the maximum communication hop count of the cluster is defined simultaneously.

[0072] Specifically, for heterogeneous spacecraft clusters, according to different requirements of space missions, the member spacecraft can be roughly divided into 3 categories according to their respective functions:

[0073] (1) Leader spacecraft

[0074] The leader spacecraft is the core of the entire spacecraft cluster and the brain of the cluster. It is responsible for receiving instructions sent from the ground and transmitting them to other spacecraft through inter-satellite links. At the same time, it integrates and processes the information fed back by other spacecraft and sends it back to the ground.

[0075] (2) Communication spacecraft

[0076] Communication spacecraft play an important role in the generation of the cluster communication network and the information transmission process. The communication payload it carries has a large capacity and can establish communication connections with multiple spacecraft in the cluster, which is a key link in the cluster information transmission.

[0077] (3) Mission execution spacecraft

[0078] The mission execution spacecraft includes spacecraft with various mission functions such as observation, docking, fuel replenishment, and capture, and is responsible for the specific execution of various space missions. During the execution process, it often needs to form corresponding configurations according to mission requirements, execute mission instructions and feedback various information.

[0079] On this basis, according to the functions of different spacecraft, the communication capacity of various spacecraft is defined. Generally, the member spacecraft are sorted according to the communication capacity as follows: communication spacecraft > leader spacecraft > mission execution spacecraft. At the same time, to reduce communication delay, the maximum communication hop count of the cluster communication network is defined according to the number and scale of the cluster members, that is, the maximum number of spacecraft included in a single communication link, providing a basis for subsequent topology generation and optimization.

[0080] In step S3, taking the leader spacecraft as the initial node of the cluster communication, considering the constraints of degree and radius, a minimum spanning tree of the communication network is generated based on the Prim algorithm and the communication capacity priority criterion to initialize the cluster topology, including the following steps:

[0081] S301. Use the leading spacecraft as the initial communication node of the cluster network, and generate a minimum spanning tree of the cluster communication network with degree and radius constraints based on the Prim algorithm;

[0082] S302. According to the communication capacity priority criterion, design the communication link to preferentially connect the spacecraft with larger communication capacity to achieve efficient utilization of communication resources.

[0083] Specifically, the process of generating a minimum spanning tree of the cluster communication network with degree and radius constraints based on the Prim algorithm in step S301 is as follows:

[0084] First, determine the weighted undirected graph G=(V, E, w) of the spacecraft cluster communication topology, where V is the vertex set, and v i is the i-th element in the vertex set, and also represents the spacecraft with serial number i in the cluster, where the vertex corresponding to the leading spacecraft is used as the root vertex. d(v i ) is the degree of vertex vi, and dc(vi) is the degree constraint of vertex vi. (v i , v j ) represents the edge between the i-th spacecraft and the j-th spacecraft., wij is the weight on the edge (v i , v j ), W = Σw ij , (v i , v j ) ∈ E m , where Em is a subset of E. T is a spanning tree centered on the root vertex, and P(v i ) is the path from v s to v i , where v i ∈V, v i ≠v s . Define Q(P(v i )) as the sum of the number of edges on the path P(v i ), r a (T) = maxQ(P(v i )) as the maximum distance from the root node to other nodes, also known as the radius of tree T, and finally define r c as the radius constraint. Then, the problem of finding the minimum spanning tree T * with degree and radius constraints of the weighted undirected graph G=(V, E, w) can be transformed into the following optimization problem

[0085] T * = minW(T)

[0086]

[0087] Further, in step S302, according to the communication capacity priority criterion, the communication link is designed to preferentially connect the spacecraft with a larger communication capacity. The specific implementation process is as follows:

[0088] For the weighted undirected graph G=(V, E, w) of the spacecraft cluster communication topology, where V is the vertex set, and v i is the i-th element in the vertex set, and also represents the spacecraft with the serial number i in the cluster. (v i , v j ) represents the edge between the i-th spacecraft and the j-th spacecraft, and wij is the weight on the edge (v i , v j ). According to the communication capacity priority criterion, the calculation method of the weight on the edge is improved. The weight calculation formula for the edge (v i , v j ) is defined as:

[0089]

[0090] Among them, represents the three components of the position of the i-th spacecraft at the current moment, σ is the communication capacity influence factor, and σ < 0. W = Σw ij , (v i , v j ) ∈ E m , where Em is a subset of E. T is a spanning tree centered on the root vertex. P(v i ) is the path from v s to v i , where v i ∈V, v i ≠v s . Define Q(P(v i )) as the sum of the number of edges on the path P(v i ). r a (T) = maxQ(P(v i )) is the maximum distance from the root node to other nodes, also known as the radius of the tree T. Finally, define rc as the radius constraint. Then, the problem of finding the minimum spanning tree T * of the weighted undirected graph G=(V, E, w) according to the communication capacity priority criterion can be transformed into the following optimization problem

[0091] T * = minW(T)

[0092]

[0093] The specific steps of the algorithm are as follows:

[0094] (1) Define the selected vertex set S = {v s}, where vs represents the leading spacecraft, and Define two variables based on the vertex vi. The first variable is the remaining degree r s (v i ) = d c (v i ), and the second variable is the distance to the root vertex Nh(v i ) = 0. Define the edge set T of the degree and radius constrained minimum spanning tree e .

[0095] (2) Screen out all the edges in the edge set ε of the weighted undirected graph G = (V, ε, ω) that have a connection relationship with the set S. Calculate the weight of each edge according to the weight calculation formula, and sort these edges in ascending order of weight and store them in the set ε e .

[0096] (3) Starting from the first edge in the set ε e , search for the corresponding starting vertex v i and ending vertex v j , where v i satisfies r s (v i ) > 0 and N h (v i ) < r c , v j satisfies r s (v j ) > 0, and add the selected edge (v i , v j ) to the set T e .

[0097] (4) Add the expanded vertex v j to the set S, update the remaining degrees of the vertices v i and v j , that is, r s (v i ) = r s (v i ) - 1, r s (v j ) = r s (v j ) - 1. Update the radius of the vertex v j , that is, N h (v j ) = N h (v i ) + 1.

[0098] (5) Based on the remaining degrees of each vertex after update, recalculate the weight of each edge according to the weight calculation formula;

[0099] (6) Judge the vertex v in the set S i If r s (v i ) = 0, or N h (v i ) = r c , then delete the vertex v i from the set S;

[0100] (7) Calculate the total number of edges in the set T e . If the number of edges is less than n - 1, then return to step (2) to continue the calculation; if T e already contains n - 1 edges, then the algorithm ends, and T e is the minimum spanning tree that meets the satisfaction and radius constraints and gives priority to capacity

[0101] In step S4, embed the algorithm into the space operation process of the cluster, and update the communication topology connection method according to the change of the relative distance between member spacecraft, so as to realize the real-time topology optimization of the cluster

[0102] Specifically, in a specific space operation scenario, first plan the trajectory of the leading spacecraft from the initial state α to the target state β in the geocentric inertial coordinate system, considering the spacecraft dynamics constraints and the maximum thrust constraints, and plan the reference trajectory of the leading spacecraft based on the shape curve approximation method. Further, adopt the swarm control-based cluster cooperative control for other member spacecraft in the cluster, so that the member spacecraft can always remain within the effective communication range during the operation process and will not collide with each other, which is convenient for observing the update situation of the cluster communication topology

[0103] Further, it is set to obtain the relative position information of member spacecraft every 10s during the operation of the cluster, and update the cluster communication network based on the designed algorithm according to this information, so as to realize the real-time topology optimization of the cluster

[0104] In step S5, when some spacecraft in the cluster fail, forcefully call the algorithm to regenerate a new communication topology to realize the reconstruction of the cluster communication topology

[0105] Specifically, in a cluster with m spacecraft, define the relative distance matrix between each spacecraft in the cluster as follows

[0106]

[0107] where l ij represents the distance between the i-th member spacecraft and the j-th member spacecraft in the cluster, and the main diagonal represents that the distance between each spacecraft and itself is 0;

[0108] Define the serial number of the failed spacecraft in the cluster as c. Then, no other spacecraft in the cluster can establish a communication connection with it. Therefore, the relative distances between the failed spacecraft and other spacecraft are no longer calculated and are all recorded as 0, resulting in a relative distance matrix as follows:

[0109]

[0110] To ensure the effective operation of the algorithm, all elements with a value of 0 in matrix A are set to Inf. Then, the algorithm will not consider the edges related to the failed spacecraft during the weight comparison process. Based on this, through the minimum spanning tree algorithm described in step S3, the communication links of other spacecraft in the cluster except the failed spacecraft can be obtained, and finally, the topology reconstruction of the entire spacecraft cluster is realized, ensuring the stability and security of cluster communication.

[0111] The method for generating and topologically optimizing a heterogeneous spacecraft cluster communication network proposed in the embodiment of the present invention divides the spacecraft in the cluster according to functional types, including leading spacecraft, communication spacecraft, and mission execution spacecraft. Different communication capacities are defined for spacecraft with different functions, and at the same time, the maximum communication hop count of the cluster is defined. Using the leading spacecraft as the initial node for generating the cluster communication network, a minimum spanning tree of the cluster communication network is generated based on the Prim algorithm under degree and radius constraints. At the same time, based on the capacity priority criterion, communication spacecraft with stronger communication capabilities are placed at the front end of the communication link to complete the initialization of the cluster communication topology. The algorithm is embedded in the cluster operation process to realize real-time topology optimization during the cluster operation. When some spacecraft in the cluster fail, the algorithm is forcibly called to perform cluster topology reconstruction to ensure the stability of the cluster communication network. This method is applicable to communication generation, topology optimization, topology reconstruction, etc. of heterogeneous spacecraft clusters under space mission conditions.

[0112] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A method for generating and topologically optimizing heterogeneous spacecraft cluster communication networks, characterized in that: The following steps are involved: S1. Establish the LVLH coordinate system with the pilot spacecraft in the heterogeneous spacecraft cluster as the center, determine the initial position and initial velocity of each member spacecraft, and realize the cluster state initialization; S2, divide the spacecraft in the cluster according to their functions, define the communication capacity of each spacecraft, and define the maximum number of communication hops of the cluster; S3, taking the pilot spacecraft as the initial node of cluster communication, considering the constraints of degree and radius, generating the minimum spanning tree of the communication network based on Prim algorithm and communication capacity priority criterion, and realizing cluster topology initialization; S4, embed the algorithm into the space operation process of the cluster, update the communication topology connection mode according to the change of the relative distance between the member spacecraft, and realize the real-time topology optimization of the cluster; S5. When some spacecraft in the cluster fail, the algorithm is forced to regenerate a new communication topology to achieve cluster communication topology reconstruction.

2. The heterogeneous spacecraft cluster communication network generation and topology optimization method according to claim 1 is characterized in that: In step S1, the LVLH coordinate system is established with the pilot spacecraft as the center, and the relative motion expression of the member spacecraft relative to the pilot spacecraft is: Among them, x i ,y i ,z i represents the component of the position vector of the i-th member spacecraft, They represent the components of the corresponding velocity vector and acceleration vector, μ represents the gravity coefficient, and m i represents the mass of the i-th member spacecraft, r f represents the magnitude of the position vector between the pilot spacecraft and the center of the Earth, ω represents the orbital angular velocity of the pilot spacecraft, Represents the components of the control force in the directions of the three coordinate axes, It represents the difference in disturbance between the pilot spacecraft and the i-th member spacecraft in the directions of the three coordinate axes. The disturbance terms involve J2 perturbation, atmospheric drag, solar radiation pressure, etc.

3. The heterogeneous spacecraft cluster communication network generation and topology optimization method according to claim 1 is characterized in that: In step S2, the spacecraft in the cluster are divided according to their functions into pilot spacecraft, communication spacecraft, and other mission execution spacecraft, and the communication capacity of each spacecraft is defined, where communication spacecraft>pilot spacecraft>mission execution spacecraft. At the same time, the maximum number of communication hops of the cluster is defined to achieve low-latency information transmission.

4. The heterogeneous spacecraft cluster communication network generation and topology optimization method according to claim 1 is characterized in that: The step S3 comprises the following steps: S301, taking the pilot spacecraft as the initial communication node of the cluster network, generating a minimum spanning tree of the cluster communication network with degree and radius constraints based on the Prim algorithm; S302. According to the communication capacity priority principle, the communication link is designed to preferentially connect to the spacecraft with larger communication capacity, so as to achieve efficient use of communication resources.

5. The heterogeneous spacecraft cluster communication network generation and topology optimization method according to claim 4 is characterized in that: The step S301 generates a minimum spanning tree of a cluster communication network with degree and radius constraints based on the Prim algorithm, and the specific implementation process is as follows: First, determine the spacecraft cluster communication topology weighted undirected graph G = (V, E, w), where V is the vertex set, v i is the i-th element in the vertex set, and also represents the spacecraft with sequence number i in the cluster, where the vertex corresponding to the pilot spacecraft is taken as the root vertex, d(v i ) is the degree of vertex vi, and dc(vi) is the degree constraint of vertex vi; (v i ,v j ) represents the edge between the i-th spacecraft and the j-th spacecraft, wij is the edge (v i ,v j ), W = Σw ij ,(v i ,v j )∈E m , where Em is a subset of E, T is a spanning tree centered on the root vertex, P(v i ) is from v s to v i The path, where v i ∈V,v i ≠v s , define Q(P(v i )) is the path P(v i ), r a (T) = maxQ(P(v i )) is the maximum distance from the root node to other nodes, also known as the radius of the tree T. Finally, r is defined c If the radius constraint is the minimum spanning tree T of the weighted undirected graph G = (V, E, w) with degree and radius constraint, then * The problem can be transformed into the following optimization problem: By finding the optimal solution to the above problem under the condition of satisfying the constraints, we can obtain the minimum spanning tree that meets the requirements.

6. The heterogeneous spacecraft cluster communication network generation and topology optimization method according to claim 4 is characterized in that: In step S302, according to the communication capacity priority criterion, the communication link is designed to preferentially connect to the spacecraft with larger communication capacity. The specific implementation process is as follows: For the spacecraft cluster communication topology weighted undirected graph G = (V, E, w), where V is the vertex set, v i is the i-th element in the vertex set, and also represents the spacecraft with sequence number i in the cluster, (v i ,v j ) represents the edge between the i-th spacecraft and the j-th spacecraft, wij is the edge (v i ,v j ), the calculation method of edge weights is improved according to the communication capacity priority criterion, and the edge (v i ,v j ) is calculated as follows: in, The three components representing the current position of the i-th spacecraft, σ is the communication capacity influencing factor, and σ<0, W=Σw ij ,(v i ,v j )∈E m , where Em is a subset of E, T is a spanning tree centered on the root vertex, P(v i ) is from v s to v i The path, where v i ∈V,v i ≠v s , define Q(P(v i )) is the path P(v i ), r a (T) = maxQ(P(v i )) is the maximum distance from the root node to other nodes, also known as the radius of the tree T. Finally, rc is defined as the radius constraint. Then, according to the communication capacity priority criterion, the minimum spanning tree T of the weighted undirected graph G = (V, E, w) with degree and radius constraints is obtained. * The problem can be transformed into the following optimization problem The specific steps of the algorithm are as follows: (1) Define the selected vertex set S = {v s }, where vs represents the pilot spacecraft, and Based on vertex vi, two variables are defined. The first variable is the residual degree r. s (v i ) = d c (v i ), the second variable is the distance to the root vertex Nh(v i )=0, define the edge set T of the minimum spanning tree with degree and radius constraints e ; (2) Filter out all the edges that are connected to the set S from the edge set ε of the weighted undirected graph G = (V, ε, ω), calculate the weight of each edge according to the weight calculation formula, and store these edges in the set ε in ascending order of weight. e ; (3) From the set ε e The first edge in the starts searching for the corresponding starting point v according to the connection relationship i and the end point v j , where v i Satisfy s (v i )>0 and N h (v i )<r c , v j Satisfy s (v j )>0, and the selected edge (v i ,v j ) Add to the collection T e ; (4) Expand the vertex v j Add to set S, for vertex v i and v j The remaining degree is updated, that is, r s (v i )=r s (v i )-1, r s (v j )=r s (v j )-1, for vertex v j The radius is updated, that is, N h (v j )=N h (v i )+1; (5) Based on the updated residual degree of each vertex, recalculate the weight of each edge according to the weight calculation formula; (6) For the vertex v in the set S i Make a judgment, if r s (v i )=0, or N h (v i )=r c , then the vertex v i Delete from set S; (7) Calculate the set T e The total number of edges in the equation. If the number of edges is less than n-1, return to step (2) to continue the calculation. If T e If n-1 edges are already contained in the algorithm, the algorithm ends. e That is the minimum spanning tree with the required satisfaction and radius constraints and capacity priority.

7. The heterogeneous spacecraft cluster communication network generation and topology optimization method according to claim 1 is characterized in that: The step S4 embeds the algorithm into the space operation process of the cluster, updates the communication topology connection mode according to the change of the relative distance between the member spacecraft, sets the relative position information of the member spacecraft to be re-acquired every 10 seconds, and updates the cluster communication network according to the information, so as to realize the real-time topology optimization of the cluster.

8. The heterogeneous spacecraft cluster communication network generation and topology optimization method according to claim 1 is characterized in that: In step S5, when some spacecraft in the cluster fail, the algorithm is forced to regenerate a new communication topology to achieve cluster communication topology reconstruction. In a cluster with m spacecraft, the relative distance matrix between the spacecraft in the cluster is defined as: Among them, l ij represents the distance between the i-th member spacecraft and the j-th member spacecraft in the cluster, and the main diagonal line indicates that the distance between each spacecraft and itself is 0; Define the serial number of the failed spacecraft in the cluster as c, then other spacecraft in the cluster cannot communicate with it, so the relative distance between the failed spacecraft and other spacecraft is no longer calculated, and is recorded as 0. The relative distance matrix is: In order to realize the effective operation of the algorithm, all elements with a value of 0 in the A matrix are set to Inf. Then, the algorithm will not consider the edges related to the failed spacecraft during the weight comparison process. On this basis, the minimum spanning tree algorithm described in step S3 can be used to obtain the communication links of other spacecraft in the cluster except the failed spacecraft, and finally realize the topological reconstruction of the entire spacecraft cluster.

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