A cellular grid-based mega constellation geo-coverage capability analysis simulation system and method

Abstract

The application discloses a kind of based on honeycomb grid giant constellation ground coverage capability analysis simulation system and method, based on H3 grid system, OsgEarth, system development of Qt, multiple sets of resolution H3 honeycomb grid are built-in in system, mapping is established between geographical space coordinates and H3 honeycomb grid, the range of area that needs to calculate coverage capability is represented using the mode of honeycomb grid index, and according to giant constellation ephemeris prediction result, the ground coverage range of giant constellation is calculated and analyzed, and the ground coverage range of constellation and satellite operation effect are simulated using the mode of OsgEarth single node.The application realizes the ground coverage capability simulation analysis of giant constellation, greatly improves the analysis and simulation efficiency of satellite coverage capability, can support the simulation simulation and coverage capability analysis of tens of thousands of satellites, with the characteristics of open source, easy to expand, multi-platform.

Description

Technical Field

[0001] This invention relates to the field of giant constellation simulation, and more particularly to a system and method for analyzing and simulating the Earth coverage capability of giant constellations based on cellular grids. Background Technology

[0002] With the advancement of aerospace technology, people are increasingly turning their attention to space, viewing artificial Earth satellites and their constellations as solutions to various problems. Low Earth orbit (LEO) satellite constellations play a crucial role in global internet, IoT, satellite remote sensing, and military applications due to their advantages such as low latency of satellite-to-ground links, low propagation loss, and high imaging resolution. However, limited by their low orbital altitude, the coverage area of ​​a single LEO satellite is typically small. Therefore, to achieve high revisit rates and high coverage, LEO satellite constellations usually have a large number of satellites. Furthermore, the high speed and short orbital period of LEO satellites result in rapid changes in their Earth coverage, posing a challenge to the accurate and efficient analysis of the constellation's Earth coverage capabilities.

[0003] Typically, analyzing and calculating satellite Earth coverage capabilities requires dividing the region into grid nodes based on the required accuracy and calculating the coverage capability of each node to reduce computational resources. The conventional approach to analyzing the Earth coverage capabilities of large low-Earth orbit constellations is as follows: Step 1, within the study area, select grid points at fixed latitude and longitude intervals on a latitude and longitude grid according to the required accuracy; Step 2, analyze the coverage of each satellite at that point point by point according to specific constraints. This approach has two problems: First, the grid point division method is not reasonable enough. Simply selecting points at equal latitude and longitude intervals leads to uneven grid point density, with higher density closer to the poles. Second, when the study area is large or the accuracy requirement is high, the number of grid points is large. Combined with the large number of satellites in a large constellation, performing coverage analysis point-by-point and satellite-by-satellite consumes a lot of computational resources, making it difficult to achieve high analysis efficiency. Furthermore, traditional satellite simulations often rely on software such as Matlab and satellite simulation toolkits (STK) to build mathematical models and perform simulations, lacking open-source and cross-platform capabilities. Summary of the Invention

[0004] The purpose of this invention is to propose a simulation system and method for analyzing the Earth coverage capability of mega constellations based on cellular grids, in order to solve the problems of unreasonable grid point division, low analysis efficiency, and inability to deploy the simulation system on multiple platforms, thereby realizing real-time analysis of the global coverage capability of mega constellations in low Earth orbit and providing intuitive visualization effects.

[0005] The technical solution for achieving the objective of this invention is: a cellular grid-based mega-constellation Earth coverage capability analysis and simulation system, comprising a system base module, a satellite management module, a coverage capability analysis module, and a visualization simulation analysis module, wherein:

[0006] The system base module uses the osg 3D rendering engine, osgEarth 3D digital earth engine library and Qt development framework. Through 3D rendering, osg provides the ability to draw basic 2D and 3D elements as well as the rendering capabilities of scenes, animations and special effects. osgEarth provides a geographic information spatial reference system. The Qt development framework encapsulates the osg 3D rendering engine and osgEarth 3D digital earth engine library to support subsequent calls.

[0007] The satellite management module predicts the ephemeris of satellites in the constellation based on the satellite parameters and converts the ephemeris coordinates from the inertial frame to the Earth-fixed frame to support the subsequent calculation and analysis of the constellation's Earth coverage capability.

[0008] The coverage capability analysis module divides the area to be analyzed into H3 cellular grids, establishes a geospatial grid index, and calculates and analyzes the constellation's Earth coverage capability based on the ephemeris forecast data calculated by the satellite management module.

[0009] The visualization simulation analysis module, based on the rendering capabilities of osg and osgEarth, realizes the simulation of constellation operation, generates and renders a heat map of constellation coverage capability, and provides a visualization interactive interface based on Qt.

[0010] Furthermore, in the system base module, the osg::Geometry class interface is used to implement the ability to draw vertices and shapes of graphic elements; the osg::Group class interface is used to organize and manage graphic elements according to nodes; the osg::MatrixTransform class interface is used to perform spatial rotation and movement of the drawn graphic elements; the osgEarth::MapNode class interface is used to load and render image, elevation, and vector data; the QWeight class interface is used to develop the system's graphical interface; and the SIGNAL() and SLOT() functions are used to implement the interaction of events in the program.

[0011] Furthermore, the satellite management module includes a constellation parameter setting module, a trajectory prediction module, and a coordinate transformation module, among which:

[0012] The constellation parameter setting module configures the two-line orbital elements TLE, the satellite ephemeris prediction time step Δt, and the ephemeris prediction time range T for each satellite in the mega-constellation. statellite-range Configure the settings, where Δt is selected based on the required accuracy for coverage capability analysis, and T... statellite-range The timeframe for coverage analysis should be included;

[0013] The trajectory prediction module uses the SGP4 model to calculate the satellite's trajectory at T statellite-range The spatial location of the satellite at each ephemeris calculation node within the time range;

[0014] The coordinate transformation module converts the predicted satellite ephemeris from geocentric inertial coordinate system coordinates to Earth-fixed coordinate system coordinates.

[0015] Furthermore, the coverage capability analysis module includes an analysis parameter setting module, a mesh generation module, and a coverage capability calculation module, wherein:

[0016] The analysis parameter setting module allows you to configure relevant parameters during the coverage capability calculation and analysis process, including the area to be analyzed and the coverage capability calculation time range T. cover-range or time T cover-moment The H3 cellular grid resolution parameter Res, where the area to be analyzed, Area, is identified using a list of latitude and longitude coordinates to represent the area's boundaries; in the coverage calculation time settings, if a time range T is set... cover-range Then calculate T cover-range The average coverage capability of the constellation satellites within the area to be analyzed, if time T is set. cover-moment， Then according to T cover-moment Instantaneous coverage capability within the constellation satellite ephemeris calculation area;

[0017] The mesh generation module obtains the set of cell grid indexes H for all cells in the area based on the set grid resolution Res and the area to be analyzed. index and each index h k By using the coordinates of the six vertices of the corresponding cellular mesh, the H3 cellular mesh data in the Area to be analyzed is obtained, where h k ∈H index， k = 1, 2, 3, ..., n, where n is the total number of grids in the region;

[0018] The coverage capability calculation module selects the corresponding coverage capability analysis mode based on the chosen coverage capability calculation time, calls the appropriate algorithm, and calculates the coverage capability of the giant constellation in each region's H3 cell grid. In the instantaneous coverage capability calculation, the coverage capability is calculated based on the satellite's position at the selected time T. cover-moment The ephemeris is used to calculate the coverage capability of the region at a selected time; in the average coverage capability calculation, the coverage capability of the satellite within the selected time range T is calculated. cover-range For each satellite ephemeris calculation time point, the instantaneous coverage capability of the region is calculated, and the average coverage capability of all ephemeris times within the time range is calculated as the average coverage capability within that time range.

[0019] Furthermore, in the coverage capability calculation module, the average coverage capability is calculated using the following method:

[0020] (1) Calculate Starlink S all single satellite i At time t in ephemeris calculationj The area of ​​ground coverage at a given time, i.e., the instantaneous area of ​​ground coverage;

[0021]

[0022] In the formula, θ is the semi-cone angle of the satellite's field of view for Earth observation or communication, and R e H is the Earth's radius. s This is the satellite's current orbital altitude. R′ is the semi-geocene angle corresponding to the coverage area, and R′ is the radius of the coverage area.

[0023] (2) Calculate the s of this single satellite i Index all cellular grids contained in the ground coverage area and increment the coverage count of the corresponding grid by one;

[0024] (3) For all satellites S all Repeat steps (1) and (2) to obtain all grids H within the computational domain Area. index At time t j The number of times it is covered, using CI_Grid(h k , t j ) represents Starlink S all At time t j Time to grid h k The instantaneous coverage capability is achieved using CI_area(t) j Characterizing Starlink S all At time t j For computational region H index The instantaneous ground coverage capability, of which h k ∈H index k = 1, 2, 3, ..., n, where n is the total number of grid cells in the region;

[0025] (4) According to the formula:

[0026]

[0027] The calculation yields h for each grid cell. k In T cover-range Average coverage CI_Grid(h k T cover-range ), combined to obtain CI_area(H index T cover-range ), as all Starlink satellites all In T cover-range Within the time frame, for region H index The ground coverage capability, i.e., the average ground coverage capability.

[0028] Furthermore, the visualization simulation analysis module includes: a giant constellation operation simulation module, a coverage capability simulation module, and a system visualization interaction module, among which:

[0029] The giant constellation operation simulation module uses Qt to call the interface for loading and rendering related elements in osgEarth. Based on the predicted constellation satellite ephemeris data, it realizes satellite operation simulation, including satellite model simulation, satellite trajectory simulation, and satellite Earth coverage envelope cone simulation. The specific method is as follows:

[0030] This code encapsulates the basic geometric element node class `osg::Geometry` of OSG, adds Starlink satellite icon models and labels to implement a Starlink satellite model node class, named `satelliteModelNodeClass`, and simulates the satellite model by setting the icon model style, size, and angle. It also encapsulates the basic geometric element node class `osg::Geometry` of OSG, adds predicted ephemeris data of Starlink satellites calculated from the SGP4 model to implement a satellite trajectory node class, named `satelliteOrbitNodeClass`, and simulates the satellite trajectory by setting the trajectory style and display period. Finally, it encapsulates the basic geometric element node class `osg::Geometry` of OSG, adds a satellite Earth coverage cone envelope based on the satellite's Earth coverage range to implement a satellite Earth coverage envelope node class, named `satelliteOrbitNodeClass`. The `satelliteEnvelopeNodeClass` class simulates the satellite's Earth coverage envelope cone by setting its color and transparency. It inherits from the `osg::Group` class to encapsulate orbit nodes, satellite model nodes, and satellite Earth coverage envelope nodes, forming the `satelliteNodeClass` class. It also implements a satellite position update callback function named `satelliteNode::statellitePosUpdata`. In each frame of `osgEarth` rendering, the `satelliteNode::statellitePosUpdata` function is called to update the display position and angle of the Starlink satellite model, satellite trajectory, and satellite Earth coverage envelope over time, thus simulating the Starlink satellite's operation.

[0031] The coverage capability simulation module uses Qt to call the rendering interfaces of relevant elements in osg and osgEarth to generate and visualize a satellite coverage capability heatmap based on an H3 grid on the 3D digital earth surface. The specific method is as follows:

[0032] Obtain the boundary vertex coordinates of each grid in the Area to be analyzed, draw the cellular grid using the osg::Geometry basic geometric element node class, and calculate the average coverage of each grid based on CI_Grid(h). k ,T cover-range The numerical value is used to fill the color of the honeycomb grid, enabling Starlink satellites to appear within a time range T. cover-range Within the area, the average ground cover capability is visualized;

[0033] The system's visual interaction module uses Qt to encapsulate time control, perspective control, information prompts, and data entry functions, enabling visual interactive operations on the system.

[0034] A simulation method for analyzing the ground coverage capability of a mega-constellation based on cellular grids is provided. Based on the aforementioned simulation system for analyzing the ground coverage capability of a mega-constellation, the method realizes the analysis of the ground coverage capability of a mega-constellation based on cellular grids.

[0035] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it performs a cellular grid-based analysis of the ground coverage capability of a mega-constellation based on the aforementioned mega-constellation ground coverage capability analysis and simulation system.

[0036] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs a cellular grid-based analysis of the ground coverage capability of a mega-constellation based on the aforementioned mega-constellation ground coverage capability analysis and simulation system.

[0037] Compared with existing technologies, this invention has the following significant advantages: 1) It uses the H3 grid system for surface spatial division and indexing, and calculates and analyzes the coverage capabilities of mega-constellation satellites based on the H3 grid. Employing the osgEarth + Qt technical approach, it renders satellites and their trajectories using a single-node method, achieving visualized simulation and system interaction of satellite and coverage capabilities. This improves the uniformity of point distribution and computational efficiency in global coverage analysis, and allows for adjustments to the grid resolution to adapt to different granularity and efficiency requirements. 2) It can visually display the constellation and coverage capability analysis results in the form of a grid heatmap. 3) All functional modules adopt an open-source, cross-platform implementation scheme, featuring configurability, portability, and high system compatibility, providing an excellent method and system for the analysis and reversal of mega-constellation Earth coverage capabilities. Attached Figure Description

[0038] Figure 1 This is a system structure diagram of the present invention.

[0039] Figure 2This is a flowchart illustrating the operation of the method of the present invention.

[0040] Figure 3 This is a diagram of covering geometric relationships.

[0041] Figure 4 Flowchart for calculating the instantaneous Earth coverage capability of a constellation.

[0042] Figure 5 Flowchart for calculating the average ground coverage capability of a constellation. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0044] This invention utilizes the H3 grid system for surface spatial partitioning, incorporating multiple grid resolutions to adapt to varying analytical precision requirements, resulting in a more rational grid division. A spatial index established based on the H3 grid system is used to calculate and analyze the Earth coverage capability of mega-constellations. A single-node approach using osgEarth is employed for satellite visualization simulation, improving computational and simulation efficiency. The system is implemented using osgEarth, Qt, and H3 technologies, featuring open-source, portable, and multi-platform characteristics, meeting the development needs of the aerospace field for domestic production and independent control. This invention provides a method and system for mega-constellation simulation and coverage capability analysis.

[0045] Figure 1 This is a structural diagram of the system of the present invention. The analysis of the Earth coverage capability of a mega-constellation based on cellular grids includes system base software, satellite management software, coverage capability analysis software, and visualization simulation analysis software. The system base software includes: osg, osgEarth, and the Qt development framework; the satellite management software includes: a constellation parameter setting module, a trajectory prediction module, and a coordinate transformation module; the coverage capability analysis software includes: an analysis parameter setting module, a grid generation module, and a coverage capability calculation module; the visualization simulation software includes: a mega-constellation operation simulation module, a coverage capability simulation module, and a system visualization interaction module.

[0046] 1. System Dock Software:

[0047] Based on osg and osgEarth, it provides visualization rendering of geospatial information, satellites, and cellular grids. It encapsulates osg and osgEarth based on Qt and provides development support for related system interfaces.

[0048] OSG is an open-source 3D real-time scene graph development engine that uses a scene tree approach to manage 3D scenes and logical groups to construct the scene tree, enabling efficient rendering and traversal. OSG provides basic capabilities for drawing 2D and 3D elements such as points, lines, surfaces, and models, as well as rendering capabilities for scenes, animations, and special effects. The `osg::Geometry` class interface enables the drawing of vertices of graphical elements, allowing for the drawing of shapes such as points, lines, and surfaces, supporting the drawing of basic elements in visualization simulation analysis modules, including satellite models, trajectories, and coverage areas. The `osg::Group` class interface organizes and manages various graphical elements according to nodes. The `osg::MatrixTransform` class interface performs spatial rotation and movement of drawn graphical elements.

[0049] osgEarth is a scalable terrain rendering toolkit for OpenSceneGraph (OSG). It is an open-source, high-performance 3D graphics toolkit. osgEarth builds a complete geospatial reference system capable of efficiently loading various types of geographic information. The osgEarth::MapNode class interface is used to load and render geographic information data such as imagery, elevation data, and vector data. This system provides visualization rendering support for satellite models, satellite trajectories, cellular grids, and sensor coverage.

[0050] The Qt development framework is a cross-platform C++ graphical user interface application development framework. During code implementation, it encapsulates osg and osgEarth to support subsequent interface code calls. Based on the Qt framework, cross-platform satellite management and coverage analysis modules were developed, and system visualization and interactive software was implemented in the visualization simulation module. The QWeight class interface was used to develop the system's graphical interface, and the SIGNAL() and SLOT() functions were used to implement event interaction in the program.

[0051] This invention uses versions osg3.4.0, osgEarth2.8.0, and Qt5.7.1, and references the compiled dynamic library in the Qt application, and references the osgQt third-party library in the Qt program to realize the encapsulation of osgEarth in the Qt window interface.

[0052] 2. Satellite management software:

[0053] The satellite management software predicts the ephemeris of satellites within the constellation based on their parameters and transforms the ephemeris coordinates from an inertial frame to a geostationary-fixed frame, supporting subsequent calculations and analysis of the constellation's Earth coverage capabilities. It includes: a constellation parameter setting module, a trajectory prediction module, and a coordinate transformation module. The constellation parameter setting module is responsible for setting the parameters of each satellite in the mega-constellation. The trajectory prediction module uses the satellite ephemeris orbit prediction model to predict the satellite's ephemeris based on these parameters. The coordinate transformation module is responsible for converting the predicted satellite ephemeris data from geocentric inertial frame coordinates to geostationary-fixed frame coordinates.

[0054] Specifically, a two-line element (TLE) method combined with the SGP4 model is used to predict satellite ephemeris. Among these methods:

[0055] The mega-constellation parameter setting module configures the two-line elements (TLE) of each satellite in the mega-constellation, the satellite ephemeris prediction time step (Δt), and the time range (T) for ephemeris prediction. statellite-range The parameters are set. Δt is selected based on the required accuracy for coverage analysis, and T... statellite-range The timeframe for coverage analysis should be included.

[0056] The trajectory prediction module, based on the set satellite data and simulation prediction parameters, calls the satellite ephemeris orbit prediction model to calculate the satellite's orbit at T... statellite-range The spatial location of satellites at each ephemeris calculation node within a time range. This invention uses the SGP4 model for satellite orbit prediction.

[0057] The coordinate transformation module is responsible for converting the predicted satellite ephemeris from geocentric inertial coordinate system coordinates to Earth-fixed coordinate system coordinates.

[0058] 3. Coverage analysis software:

[0059] The coverage capability analysis software divides the area to be analyzed into an H3 cellular grid, establishes a geospatial grid index, and calculates and analyzes the Earth coverage capability of the constellation based on the ephemeris prediction data calculated by the satellite management module. It includes: a constellation parameter setting module, a trajectory prediction module, and a coordinate transformation module. The constellation parameter setting module is responsible for setting the parameters of various satellites in the mega-constellation. The trajectory prediction module calls the satellite ephemeris orbit prediction model to predict the satellite's ephemeris based on the satellite parameters. The coordinate transformation module is responsible for converting the predicted satellite ephemeris data from geocentric inertial coordinates to Earth-fixed coordinates.

[0060] The analysis parameter setting module allows you to configure relevant parameters during the coverage capability calculation and analysis process, including the area to be analyzed and the coverage capability calculation time range (T). cover-range ) or time (T) cover-momentH3 cell grid resolution parameters (Res). The area to be analyzed is identified using a latitude and longitude list to represent the area's boundaries. In the coverage calculation time settings, if a time range (T) is set... cover-range If ), then calculate T. cover-range The average coverage capability of the constellation satellites within the area to be analyzed; the time setting is T. cover-moment And it must be T statellite-range (Calculate the time of a certain ephemeris in T), then according to T cover-moment The H3 grid system provides instantaneous coverage of the constellation satellite ephemeris calculation area. It offers 16 resolution parameters (Res) from level 0 to 15, with higher Res levels resulting in higher grid accuracy.

[0061] The mesh generation module, based on the set mesh resolution (Res) and the area to be analyzed (Area), uses the H3 mesh system (polygonToCells interface) to obtain the set of all cell grid indices (H... index ) and each index h k (h k ∈H index The coordinates of the six vertices of the cellular grid (k = 1, 2, 3, ..., n, where n is the total number of grids in the area) are used to obtain the H3 cellular grid data in the area to be analyzed.

[0062] The coverage capability calculation module selects the corresponding coverage capability analysis mode based on the chosen calculation time, calls the appropriate algorithm, and calculates the coverage capability of the mega-constellation within each region's H3 cell grid. In the instantaneous coverage capability calculation, based on the satellite's position at the selected time T... cover-moment The ephemeris data is used to calculate the coverage capability of the region at a selected time. In the average coverage capability calculation, the coverage capability of the satellite within the selected time range T is calculated. cover-range For each satellite ephemeris calculation time point, the instantaneous coverage capability of the region is calculated, and the average coverage capability of all ephemeris times within the time range is calculated as the average coverage capability within that time range.

[0063] 4. Visual simulation software:

[0064] The visualization simulation analysis software, based on the rendering capabilities of osg and osgEarth, simulates the operation of a constellation, generates and renders a heatmap of constellation coverage capability, and provides a Qt-based interactive visualization interface. It includes: a giant constellation operation simulation module, a coverage capability simulation module, and a system visualization interaction module. The giant constellation operation simulation module uses Qt to call the rendering interface of relevant elements in osgEarth, and performs satellite operation simulation based on predicted constellation satellite ephemeris data, including satellite models, satellite trajectories, and satellite Earth coverage simulation. The coverage capability simulation module uses Qt to call the rendering interface of relevant elements in osg and osgEarth, generates a satellite coverage capability heatmap, and performs visualization rendering. The system visualization interaction module uses Qt to encapsulate time control, viewpoint control, information prompts, and data entry functions, enabling interactive visualization of the system.

[0065] The giant constellation operation simulation module encapsulates the basic geometric element node class of OSG (osg::Geometry), adds satellite icon models and labels, and implements a satellite model node class (named: satelliteModelNodeClass). By setting the icon model style, size, angle, etc., satellite model simulation is achieved. The module also encapsulates the basic geometric element node class of OSG (osg::Geometry), adds satellite forecast ephemeris data, and implements a satellite trajectory node class (named: satelliteOrbitNodeClass). By setting the trajectory style, trajectory display period, etc., satellite trajectory simulation is achieved. Finally, the module encapsulates the basic geometric element node class of OSG (osg::Geometry), adds a satellite Earth coverage cone envelope based on the satellite's Earth coverage range, and implements a satellite Earth coverage envelope node class (named: satelliteEnvelopeNodeClass). By setting the envelope's color and transparency, satellite Earth coverage range simulation is achieved. It inherits from the osg::Group class to encapsulate orbital nodes and satellite model nodes, forming a satellite node class (named: satelliteNodeClass), and implements a satellite position update callback function (named: satelliteNode::statellitePosUpdata). In each frame of rendering in the osgEarth engine, the satellite position update callback function (named satelliteNode::statellitePosUpdata) is called to update the display position and angle of the Starlink satellite model, satellite trajectory, and satellite Earth coverage envelope over time, thus simulating the operation of Starlink satellites.

[0066] The coverage capability simulation module calls the A algorithm (cellToBoundary) in the H3 grid system to obtain the coordinates of the six vertices of each cell grid. It uses Qt to call the osgEarth related elements to draw and render the interface (osg::Geometry). Based on the calculated satellite Earth coverage capability values ​​in each grid, it realizes the visualization of the satellite Earth coverage capability heat map.

[0067] The system visualization and interaction module uses Qt to implement a visualized system interaction interface, providing functions such as operation control of constellation satellites and view control of the 3D Earth and coverage capability heat map grid in osgEarth.

[0068] Figure 2 This is a flowchart illustrating the operation of the method of the present invention.

[0069] First, the relevant parameters for coverage capability analysis are set. Then, the area to be analyzed is divided into a cellular grid according to the required analysis accuracy. Next, the relevant parameters of the constellation satellites to be calculated are set, and the satellite ephemeris is predicted. Based on the predicted satellite ephemeris, a visual simulation of the satellites is performed. Then, the coverage capability of the constellation to the cellular grid in each area to be analyzed is calculated based on the predicted ephemeris of each satellite, a coverage capability heatmap is generated, and the effect is displayed.

[0070] Step 1: Import constellation satellite data and set constellation simulation parameters.

[0071] Import the two-line orbital elements (TLE) of each satellite in the giant constellation to be analyzed and calculated, and set the satellite ephemeris prediction time step (Δt) and the time range for which the ephemeris needs to be predicted (T). statellite-range ) parameters. Supporting ephemeris predictions for subsequent mega-constellation satellites.

[0072] In Example 1 of this invention, two lines of orbital elements data for all Starlink satellites published on the NORAD website are used as the data for the mega-constellation satellites. The satellite ephemeris prediction time step (Δt) is set to 60 seconds, and the ephemeris prediction time range (T) is... statellite-range The period is from 00:00 on November 24, 2022 to 00:30 on November 24, 2022.

[0073] Step 2: Set coverage analysis parameters

[0074] The relevant parameters in the coverage capability calculation and analysis process are set, including the coverage capability analysis area (Area), H3 cell grid resolution parameter (Res), and coverage capability calculation time range (T). cover-range ) or time (T) cover-moment ).

[0075] In Example 1 of this invention, the entire globe is selected as the area for calculating coverage capability, the H3 cellular grid resolution parameter (Res) is 2, and the coverage capability calculation time range (T) is... cover-range The period is from 00:10 to 00:20 on November 24, 2022.

[0076] Step 3: Divide the area to be analyzed into a cellular mesh and create an index.

[0077] Using the H3 grid system algorithm (polygonToCells interface), the selected region is divided into hexagonal honeycomb grids of a specified resolution according to the selected grid resolution level, and spatial indexing is performed based on the grid to obtain the grid index set (H index ).

[0078] In Example 1 of this invention, the resolution level of the grid is 2, and the average area of ​​the cellular grid worldwide is 86745.8540347 km². 2 The average edge length of the cellular grid is 158.244655800 km, with a total of 5,882 grids.

[0079] Step 4: Predict satellite ephemeris and orbit

[0080] Based on the set constellation satellite parameter data, the satellite orbit prediction model is invoked to calculate the satellite's position within the ephemeris prediction time range (T). statellite-range The ephemeris data within the range of satellite orbit prediction models is converted from satellite ephemeris data in geocentric inertial coordinates to coordinates in geocentric inertial coordinates.

[0081] In Example 1 of this invention, Starlink satellite data is used as an example to calculate T using the SGP4 model program. statellite-range This study uses satellite ephemeris data from 00:00 to 00:30 on November 24, 2022, at intervals of Δt every 60 seconds, in the True Equator and Mean Equinox of Date Coordinate System (TEMED). The ephemeris data in the TEMED coordinate system is then converted to ephemeris data in the J2000 coordinate system, and finally converted to data in the WGS84 coordinate system. In this example, the J2000 coordinate system serves as an intermediate coordinate system, connecting the TEMED and WGS84 coordinate systems. (Gong Qiuwu, Intelligent Autonomous Orbit Determination Technology for Emergency Spaceflight Missions Based on Space-Based Navigation, Master's Thesis.)

[0082] Step 5: Calculate constellation coverage within the area to be analyzed.

[0083] Based on the cellular grid index calculated in step 3 and the satellite ephemeris data predicted in step 4, calculate the total number of cellular grids (H) within the area to be analyzed (Area) at the coverage capability calculation time. index The coverage capability. When the coverage capability is calculated at an instant (T). cover-moment If the constellation is located at T, then calculate the constellation at T. cover-moment Time to H index The instantaneous coverage to ground capability, i.e., based on the satellite's position at T... cover-moment The ephemeris was used to calculate the effect on H. index Coverage capability. When the coverage capability is calculated over a time range (T). cover-range If the constellation is located at T, then calculate the constellation at T. cover-range Internal to H index The average coverage to ground, i.e., the calculation of the constellation's coverage on T cover-range For each satellite ephemeris calculation time point within the range, for H index The instantaneous coverage capability, and the statistical results of constellations in T cover-range H within range index The average instantaneous coverage capability, as a constellation in T cover-range Internal to H index Average coverage.

[0084] In Example 1 of this invention, the average ground coverage capability of Starlink is calculated. The calculation is performed based on the coverage capability calculation time range (T) set in step 2. cover-range First, calculate the S values ​​of all Starlink satellites. all In T cover-range Each ephemeris calculation time node t j (t j ∈T cover-range j = 1, 2, ..., n, where n is T cover-range The total number of ephemeris calculation nodes included) on all grids in the area to be analyzed (H) index The instantaneous Earth coverage capability of Starlink satellites was calculated, and the location of Starlink satellites at T was determined. cover-range Average ground coverage within the range.

[0085] First, calculate Starlink S based on the visibility constraint in the following formula. all single satellite i (s i ∈S all (i = 1, 2, 3, ..., n, where n is the total number of satellites in Starlink) at t j The ground coverage area at any given time is shown in the attached figure. Figure 3 As shown:

[0086]

[0087] In the formula, θ is the semi-cone angle of the satellite's field of view for Earth observation or communication, and R e H is the Earth's radius. s This is the satellite's current orbital altitude. R' is the semi-geocene angle corresponding to the coverage area, and R′ is the radius of the coverage area.

[0088] Then, the single star s is calculated using the above method. i At time t j After determining the coverage area, the H3 grid system interface (polygonToCells) is called to calculate the s of a single satellite. i Index all cellular grids contained within the ground coverage area and increment the coverage count of the corresponding grid by one. For all satellites S all After repeating the above steps, all grids H within the computational domain Area are finally obtained. index At time t j The number of times it is covered, using CI_Grid(h k , t j ) represents Starlink S all At time t j Time to grid h k (h k ∈H index， The instantaneous coverage capability of (k = 1, 2, 3, ..., n, where n is the total number of grids in the region) is calculated using CI_area(t). j Characterizing Starlink S all At time t j For computational region H index Its instantaneous ground coverage capability.

[0089] Finally, according to the formula:

[0090]

[0091] Among them, t j For T cover-range At some point in time, n is T cover-range The number of all moments included. The value h for each grid is calculated. k (h k ∈H index ) in T cover-range Average coverage CI_Grid(h k T cover-range ), combined to obtain CI_area(H index T cover-range ), as all Starlink satellites all In Tcover-range Within the time frame, for region H index The ground coverage capability, i.e., the average ground coverage capability.

[0092] Step 6: Satellite Operation Simulation

[0093] This code encapsulates basic OSG geometric element nodes, adds satellite icon models and labels to create satellite model nodes, and adds satellite ephemeris data to these nodes to simulate satellite orbits. Finally, it calls a callback function in each frame of osgEarth rendering to update the satellite's position, thus simulating satellite operation.

[0094] In Example 1 of this invention, the basic geometric element node class of osg (osg::Geometry) is encapsulated, and Starlink satellite icon models and labels are added to implement a Starlink satellite model node class (named: satelliteModelNodeClass). The basic geometric element node class of osg (osg::Geometry) is also encapsulated, and the predicted ephemeris data of Starlink satellites calculated from the SGP4 model is added to implement a satellite trajectory node class (named: satelliteOrbitNodeClass). Furthermore, the osg::Group class is inherited to encapsulate the orbital nodes and satellite model nodes, forming a satellite node class (named: satelliteNodeClass), and a satellite position update callback function (named: satelliteNode::statellitePosUpdata) is implemented. In the rendering of each frame of osgEarth, the satellite position update callback function (satelliteNode::statellitePosUpdata) is called to update the displayed position of the Starlink satellite, realizing the simulation of Starlink satellite operation.

[0095] Step 7: Visualize the coverage effect

[0096] Using Qt to call the osgEarth related element drawing and rendering interface, a heat map of satellite earth coverage capability is realized based on the calculated H3 cellular grid data and the calculated satellite coverage capability values ​​of each grid.

[0097] In Example 1 of this invention, the boundary vertex coordinates of each grid in the area to be analyzed are obtained by calling the H3 grid system interface (cellToBoundary). The osg basic geometric element node class (osg::Geometry) is used to draw the cellular grid, and the average coverage of each grid is calculated based on CI_Grid(h k T cover-range The numerical value is used to fill the color of the honeycomb grid, enabling Starlink satellites to appear within a time range T.cover-range Within the area, the average ground cover capability is visualized.

[0098] Figure 3 This is a diagram illustrating the satellite's coverage area over the Earth.

[0099] In the formula, θ is the semi-cone angle of the satellite's field of view for Earth observation or communication, and R e H is the Earth's radius. s This is the satellite's current orbital altitude. R' is the semi-geocene angle corresponding to the coverage area, and R′ is the radius of the coverage area. The formulas for calculating R′ are as follows.

[0100]

[0101] Based on the calculation time of the designed land coverage capacity, determine the calculation mode of the land coverage capacity. If the calculation time is a specific moment, it is an instantaneous land coverage capacity calculation; if the calculation time is a time range, it is an average land coverage capacity calculation.

[0102] Figure 4 This is a flowchart of the calculation process for the instantaneous Earth coverage capability of a constellation.

[0103] Step 1: According to Figure 3 The principle behind the diagram illustrating the coverage area of ​​a satellite over the Earth, and the calculation of the coverage area of ​​a single satellite in a constellation. i At time T cover-moment At that time, the coverage area of ​​the ground (area(T)) cover-moment s i ).

[0104] Step 2: Calculate satellite s according to process 1 i Coverage area (T) cover-moment s i The satellite s was calculated using the H3 grid system. i At time T cover-moment The grid covered at that time and its corresponding grid index.

[0105] Step 3: Increment the number of times the corresponding grid is covered by one.

[0106] Step 4: Determine if the traversal calculation of all satellites in the constellation has been completed. If not, return to Step 1. If yes, proceed to Step 5.

[0107] Step 5: Statistically obtain all grid H values ​​in the area to be analyzed. index At time T cover-moment The instantaneous Earth coverage capability of a constellation is calculated by the number of times it is covered by all satellites in the constellation.

[0108] Figure 5This is a flowchart for calculating the average Earth coverage capability of a constellation.

[0109] Step 1: Set the time range T cover-range Ephemeris calculation for a certain time point t j Incorporating the calculation process of the instantaneous ground coverage capability of the constellation (e.g.) Figure 4 T (as shown) cover-moment Calculate the total number of satellites in the constellation at t j The coverage area of ​​the Earth at any given time, and the constellation at t j Instantaneous ground coverage capability at any given moment.

[0110] Step 2: Determine if the time range T has been completed. cover-range All ephemeris calculations within the time t j Calculate the instantaneous ground coverage capability of the constellation at any given time. If yes, proceed to step 3; otherwise, repeat step 1.

[0111] Step 3: Obtain the time range T cover-range At all ephemeris calculation times, the constellation corresponds to the grid H. index The number of times it is covered.

[0112] Step 4: Calculate the average number of times all grids are covered over time, which will be used as the constellation's average ground coverage capability.

[0113] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0114] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A simulation system for analyzing the ground coverage capability of a giant constellation based on a cellular grid, characterized in that, It includes a system base module, a satellite management module, a coverage capability analysis module, and a visualization simulation analysis module, among which: The system base module uses the osg 3D rendering engine, osgEarth 3D digital earth engine library and Qt development framework. Through 3D rendering, osg provides the ability to draw basic 2D and 3D elements as well as the rendering capabilities of scenes, animations and special effects. osgEarth provides a geographic information spatial reference system. The Qt development framework encapsulates the osg 3D rendering engine and osgEarth 3D digital earth engine library to support subsequent calls. The satellite management module predicts the ephemeris of satellites in the constellation based on the satellite parameters and converts the ephemeris coordinates from the inertial frame to the Earth-fixed frame to support the subsequent calculation and analysis of the constellation's Earth coverage capability. The coverage capability analysis module divides the area to be analyzed into H3 cellular grids, establishes a geospatial grid index, and calculates and analyzes the constellation's Earth coverage capability based on the ephemeris forecast data calculated by the satellite management module. The visualization simulation analysis module, based on the rendering capabilities of osg and osgEarth, realizes the simulation of constellation operation, generates and renders a heat map of constellation coverage capability, and provides a visualization interactive interface based on Qt. The average coverage calculation method within the coverage calculation module is as follows: (1) Calculate Starlink single satellite Time for ephemeris calculation The area of ​​ground coverage at a given time, i.e., the instantaneous area of ​​ground coverage; ； In the formula The semi-cone angle is the field of view for satellite Earth observation or communication. For the Earth's radius, This represents the satellite's current orbital altitude. The half-geocene angle corresponding to the covered area. The radius of the coverage area; (2) Calculate the value of this single satellite Index all cellular grids contained in the ground coverage area and increment the coverage count of the corresponding grid by one; (3) For all satellites Repeat steps (1) and (2) to obtain the region to be analyzed. All cellular grid index sets within At any moment The number of times it is covered, using Starlink At any moment Time to grid Its instantaneous coverage capability, with Characterizing Starlink At any moment For the computational region Its instantaneous ground coverage capability, among which , , The total number of grid cells in the region; (4) According to the formula: ； Where m is the time range The time point for ephemeris calculation taken inside The total number; Calculate each grid exist Average coverage Combined to obtain As all Starlink satellites exist Within a time frame, for the region The ground coverage capability, i.e., the average ground coverage capability.

2. The cellular grid-based mega-constellation ground coverage capability analysis and simulation system according to claim 1, characterized in that, In the system base module, the osg::Geometry class interface is used to implement the ability to draw vertices and shapes of graphic elements; the osg::Group class interface is used to organize and manage graphic elements according to nodes; the osg::MatrixTransform class interface is used to perform spatial rotation and movement of the drawn graphic elements; the osgEarth::MapNode class interface is used to load and render image, elevation, and vector data; the QWidget class interface is used to develop the system's graphical interface; and the SIGNAL() and SLOT() functions are used to implement the interaction of events in the program.

3. The cellular grid-based mega-constellation ground coverage capability analysis and simulation system according to claim 1, characterized in that, The satellite management module includes a constellation parameter setting module, a trajectory prediction module, and a coordinate transformation module, among which: The constellation parameter setting module sets the two rows of orbital elements for each satellite in the giant constellation. Satellite ephemeris prediction time step The time range that the ephemeris needs to predict Configure the settings, including Select the appropriate level of accuracy based on the coverage capability analysis requirements. The timeframe for coverage analysis should be included; The trajectory prediction module uses the SGP4 model to calculate the satellite's trajectory. The spatial location of the satellite at each ephemeris calculation node within the time range; The coordinate transformation module converts the predicted satellite ephemeris from geocentric inertial coordinate system coordinates to Earth-fixed coordinate system coordinates.

4. The cellular grid-based mega-constellation ground coverage capability analysis and simulation system according to claim 1, characterized in that, The coverage capability analysis module includes an analysis parameter setting module, a mesh generation module, and a coverage capability calculation module, among which: The analysis parameter setting module allows you to configure relevant parameters during the coverage calculation and analysis process, including the area to be analyzed. Coverage capability calculation time range or moment H3 cellular grid resolution parameters The region to be analyzed The boundaries of the area are identified using a list of latitude and longitude coordinates; in the coverage calculation time settings, if a time range is set... Then calculate The average coverage capability of the constellation satellites within the area to be analyzed, if the time setting is... According to Instantaneous coverage capability within the constellation satellite ephemeris calculation area; The mesh generation module obtains a set of all cell grid indexes within the set mesh resolution Res and the area to be analyzed, based on the set mesh resolution Res and the area to be analyzed. and each index By using the coordinates of the six vertices of the corresponding cellular mesh, the H3 cellular mesh data in the Area to be analyzed is obtained. , , The total number of grid cells in the region; The coverage capability calculation module selects the corresponding coverage capability analysis mode based on the chosen coverage capability calculation time, calls the appropriate algorithm, and calculates the coverage capability of the giant constellation in each region's H3 cell grid. In the instantaneous coverage capability calculation, the coverage capability is determined based on the satellite's position at the selected time. The ephemeris is used to calculate the coverage capability of the region at a selected time; in the average coverage capability calculation, the coverage capability of the satellite within the selected time range is calculated. For each satellite ephemeris calculation time point, the instantaneous coverage capability of the region is calculated, and the average coverage capability of all ephemeris times within the time range is calculated as the average coverage capability within that time range.

5. The cellular grid-based mega-constellation ground coverage capability analysis and simulation system according to claim 1, characterized in that, The visualization simulation analysis module includes: a giant constellation operation simulation module, a coverage capability simulation module, and a system visualization interaction module, among which: The giant constellation operation simulation module uses Qt to call the interface for loading and rendering related elements in osgEarth. Based on the predicted constellation satellite ephemeris data, it realizes satellite operation simulation, including satellite model simulation, satellite trajectory simulation, and satellite Earth coverage envelope cone simulation. The specific method is as follows: This code encapsulates the basic OSG geometric element node class `osg::Geometry`, adds Starlink satellite icon models and labels, and implements a Starlink satellite model node class named `satelliteModelNodeClass`. By setting the icon model style, size, and angle, it achieves satellite model simulation. It also encapsulates the basic OSG geometric element node class `osg::Geometry`, adds predicted ephemeris data of Starlink satellites calculated from the SGP4 model, and implements a satellite trajectory node class named `satelliteOrbitNodeClass`. By setting the trajectory style and trajectory display period, it achieves satellite trajectory simulation. Finally, it encapsulates the basic OSG geometric element node class `osg::Geometry`, adds a satellite Earth coverage cone envelope based on the satellite's Earth coverage range, and implements a satellite Earth coverage envelope node class named `satelliteOrbitNodeClass`. The `satelliteEnvelopeNodeClass` class simulates the satellite's Earth coverage envelope cone by setting its color and transparency. It inherits from the `osg::Group` class to encapsulate orbit nodes, satellite model nodes, and satellite Earth coverage envelope nodes, forming the `satelliteNodeClass` class. It also implements a satellite position update callback function named `satelliteNode::statellitePosUpdata`. In each frame of `osgEarth` rendering, the `satelliteNode::statellitePosUpdata` function is called to update the display position and angle of the Starlink satellite model, satellite trajectory, and satellite Earth coverage envelope over time, thus simulating the Starlink satellite's operation. The coverage capability simulation module uses Qt to call the rendering interfaces of relevant elements in osg and osgEarth to generate and visualize a satellite coverage capability heatmap based on an H3 grid on the 3D digital earth surface. The specific method is as follows: Obtain the boundary vertex coordinates of each grid in the Area to be analyzed, draw the cellular grid using the osg::Geometry basic geometric element node class, and calculate the average coverage of each grid. Numerical values ​​are used to fill the color of the honeycomb grid, enabling Starlink satellites to appear within a specific time range. Within, for the region Visualization of average ground coverage capability; The system's visual interaction module uses Qt to encapsulate time control, perspective control, information prompts, and data entry functions, enabling visual interactive operations on the system.

6. A simulation method for analyzing the ground coverage capability of a giant constellation based on a cellular grid, characterized in that, Based on the giant constellation ground coverage capability analysis and simulation system according to any one of claims 1-5, the analysis of the giant constellation ground coverage capability based on cellular grid is realized.

7. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, it performs a cellular grid-based analysis of the ground coverage capability of a mega-constellation based on the mega-constellation ground coverage capability analysis and simulation system according to any one of claims 1-5.

8. A computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, it performs a cellular grid-based analysis of the ground coverage capability of a mega-constellation based on the mega-constellation ground coverage capability analysis and simulation system according to any one of claims 1-5.

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