CN113283075A

CN113283075A - Large-scale satellite scene-oriented lightweight simulation architecture design method

Info

Publication number: CN113283075A
Application number: CN202110558523.8A
Authority: CN
Inventors: 周海波; 徐震杰; 伍汉霖; 刘晓宇; 马婷
Original assignee: Nanjing University
Current assignee: Nanjing University
Priority date: 2021-05-21
Filing date: 2021-05-21
Publication date: 2021-08-20
Anticipated expiration: 2041-05-21
Also published as: CN113283075B

Abstract

A design method of a lightweight simulation architecture for an ultra-dense large-scale satellite scene comprises the following steps: designing a simulation control abstract NodeFactory type of an auxiliary management scene entity, maintaining unique time by using a single-case mode, and distributing a unique identity to each satellite node case; specifically, an abstract Node type of a satellite Node with a minimum physical unit is designed to be used as a simulation base stone to represent an actual satellite in a simulation scene, and satellite related parameters are stored; designing a single-layer Constellation abstract Constellation type formed by logically combining satellite nodes, wherein the single-layer Constellation abstract Constellation type comprises Constellation composition parameters, satellite links and Constellation motion simplification; designing a final Simulation scene abstract Simulation type formed by combining a plurality of constellations facing a user, and packaging a common method and a bottom layer interface for facilitating large-scale satellite Simulation; and compiling a main script according to the abstract type for simulation.

Description

Large-scale satellite scene-oriented lightweight simulation architecture design method

Technical Field

The invention belongs to the field of satellite simulation, and particularly relates to a design method of a lightweight simulation architecture for an ultra-dense large-scale satellite scene.

Background

Satellite technology is in a rapid development stage, especially for low-earth orbit satellites, which can provide mobile users with a quality of service not inferior to that of terrestrial networks while achieving full coverage, and can provide lower propagation delay than any terrestrial fiber networks in terms of long-distance data transmission. The construction of the low-orbit satellite constellation network has important value and significance for completing a ground 5G network and realizing the full coverage of the ground network, the extremely small propagation delay and the larger signal bandwidth of the low-orbit satellite constellation network have an important role in constructing an air high-speed data transmission network wrapping the earth, and the low-orbit satellite constellation which is already constructed or is constructed at present has the following advantages: teledesic, Iridium, Globalstar, Oneweb, Starlink, etc., have been the topic and popular research objects of common interest at home and abroad for a long time.

However, low orbit satellites rely on their orbit heights to obtain a gain of a very low transmission delay and a first-level high data bandwidth, and the construction of low orbit satellite constellations is often much more complex than medium orbit satellite constellations and synchronous orbit satellite constellations. The low-orbit constellation consists of tens or even hundreds of satellites, and the Starlink plan proposed by SpaceX recently has more than ten thousand satellite scales under continuous expansion, which brings huge challenges to the simulation of satellite scenes by using a traditional mode.

Conventional node mobility simulators simulate the actual mobility patterns of satellite nodes in a given scenario and generate a tracking file that records the mobility trajectories of all simulated nodes. The most common node mobility simulator in the field of satellite simulation is the STK (system tool kit), which is a commercial software developed by AGI corporation for analyzing and visualizing complex systems in the field of aerospace, with a rather complex program architecture. This makes the STK possess many features and also causes it to occupy considerable computing resources, and it is difficult to realize simulation research of ten thousand level satellites using the STK on a personal computer. Although the STK provides an external expansion interface, this cannot solve the problem of slow operation caused by the complex kernel thereof, and the actual function of the software does not completely coincide with the experimental purpose of large-scale mobile node simulation. Furthermore, STK is only allowed to use old versions in the country due to external factors.

In summary, compared with the prior art, the invention has the following advantages: 1. completely decoupled from the traditional satellite simulation software, customized for simulation experiment individuation 2, light-weight architecture convenient for realizing ultra-dense large-scale satellite constellation simulation 3, modular design ensures the flexibility and expandability of the simulation architecture

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a design method of a lightweight simulation architecture for an ultra-dense large-scale satellite scene. Aiming at the ultra-large-scale low-orbit Walker satellite constellation, the method realizes the construction of the satellite constellation, the data calculation and the acquisition and storage of the satellite operation result by using a lightweight simulation architecture, and can simulate the low-orbit satellite constellation at ten thousand levels.

The technical scheme adopted by the invention is as follows: a design method of a lightweight simulation architecture facing an ultra-dense large-scale satellite scene is characterized in that the abstraction of a node workshop of a scene entity is managed in a design and management assisting mode, a single-case mode is used for maintaining simulation scene time, and a unique identity is distributed to each satellite node case; the method comprises the following steps: step 1, designing an abstract Node type of a satellite Node with a minimum physical unit, representing an actual satellite in a simulation scene as a simulation base stone, and storing satellite related parameters; step 2, designing a single-layer Constellation abstract Constellation type formed by logically combining satellite nodes, wherein the single-layer Constellation abstract Constellation type comprises Constellation composition parameters, satellite links and Constellation motion simplification; step 3, designing a final Simulation scene abstract Simulation type formed by combining a plurality of constellations facing a user, and packaging a common method and a bottom layer interface for facilitating large-scale satellite Simulation; designing an interface abstract DataBase type for managing DataBase reading and writing, and storing the reading and writing in real time according to research requirements; and compiling a main script according to the abstract type for simulation.

Step 1, performing minimum unit design: the minimum unit design comprises the abstraction of a satellite node of a basic physical entity unit and the abstraction of a node workshop of an auxiliary management scene entity; the abstract design of the satellite node comprises a simulation target requirement including but not limited to a node unique identification number, a three-dimensional coordinate of a geocentric earth fixed polar coordinate system, an operation orbit parameter, a constellation information and a satellite name, and the abstract of the node workshop uses a singleton mode to maintain simulation scene time and distributes a unique identity to each satellite node instance;

step 2, building a satellite scene logic structure: designing an abstraction of a satellite constellation and a final simulation scene; the satellite constellation abstraction comprises satellite constellation information, links to all contained satellite instances, a satellite constellation initialization method and a satellite motion algorithm designed for simplified operation, and the final simulation scene abstraction comprises simulation scene information, links to the contained satellite constellation instances, a common method for simulation scenes and a bottom layer interface;

step 3, starting simulation and external interaction: the simulation and interaction comprises the abstraction of a design database storage interface and a simulation main program; designing a database to store interface abstractions and simulation main scripts; the database interface abstract packaging is used for connecting, reading, modifying, deleting and adding all details of a database and customizing a data storage method, and the simulation main script comprises all data information of a simulation scene;

in step 1, the abstract design of the satellite node is formed by extracting common and essential characteristics according to experimental purposes and targeted simulation requirements and combining and reconstructing: the method comprises the basic characteristics of a satellite physical entity, including but not limited to a node unique identification number, three-dimensional coordinates of a geocentric earth fixed polar coordinate system, operation orbit parameters, constellation information and a satellite name;

included among these must be the following fields:

m _ id, which represents the unique identification of the satellite instance individual and is configured by the unique instance abstracted by the node workshop;

the m _ currentPosition represents the real-time position of the satellite instance at a specific simulation moment, and adopts an LLA coordinate system, wherein the LLA coordinate system represents a geocentric fixed polar coordinate system and comprises parameters of latitude, longitude and altitude;

m _ inclination, which represents the inclination angle parameter of the orbit of the satellite instance, wherein the orbit eccentricity is zero under the default condition, namely the orbit is a perfect circle orbit with the geocenter as the center of a circle;

m _ uid, which represents the link to the satellite constellation where the satellite instance is located, is a null link by default and is configured when the constellation is formed;

the m _ constellationMessage is information of the constellation of the satellite to which the satellite instance belongs, indicates the logical position of the constellation of the satellite, includes the number of the orbit and the number of the position in the orbit, is empty by default, and is configured when forming the constellation;

m _ name, which represents the name of the satellite instance, is not unique, but may contain logical location information; the system is used for searching according to names and database storage, is set when the images are visualized, and is empty by default;

among the fields that may be added are:

the m _ RAAN represents the ascent intersection point right ascension of the satellite example, if the orbit model is an ellipse model and needs to be set, the intersection relation between the orbit plane and the earth equator plane is described, the intersection points are the ascent intersection point and the descent intersection point respectively, the ascent intersection point right ascension represents the radial included angle between the ascent intersection point and the vernal equinox, and the vernal equinox is regarded as the intersection point between the meridian and the equator plane for the sake of neglecting the influence caused by the revolution of the earth and simplifying the processing;

m _ eccentricity, representing the eccentricity of the orbit of the satellite instance, describing the shape of the elliptical orbit;

m _ perigeeAngle, which represents the included angle between the near point of the orbit of the satellite instance and the elevation intersection point, and describes the relative position relation between the elliptical orbit and the earth;

m _ true anomallly, which represents the included angle between the position of the satellite in the orbital plane and the near-field point and is used for describing the position of the satellite in the satellite orbit;

the m _ antenna message represents antenna information loaded on the satellite example, and comprises information such as the type, the direction, the opening angle, the frequency, the bandwidth, the power and the like of each antenna, and is used for describing a physical connection mode of satellite communication or satellite and ground communication;

the m _ linkMessage represents the inter-satellite link connection logical relationship of the satellite and is used for describing the formation form of inter-satellite networking in specific constellation design;

in the step 1, the abstraction of a node workshop of a scene entity is assisted to be managed, simulation scene time is maintained by using a singleton mode, a unique identity is distributed to each satellite node instance, and a management object comprises the simulation scene time, the generation of the unique identity and a satellite node instance link set;

the simulation scene time represents the current time in the simulation, is used for recording the whole simulation scene time with physical entity motion change along with the time change after the simulation scene time is established, needs to be synchronously modified when the time described by the simulation scene changes, and is a unique time mark;

the satellite node instance link set represents a data set which records all satellite node links in a scene and can be quickly inquired;

the unique identification represents a unique identity of the satellite node instance in the simulation scene, and the satellite instance link can be quickly searched through the satellite instance link set according to the unique identification so as to inquire satellite data;

the generation of the unique identification mark indicates that in the design of the satellite node abstraction, when the satellite node abstraction is embodied into an instance, the unique identification mark m _ id needs to be applied to a node plant instance, in the process, the node plant instance returns an unassigned id value, the id value is bound with a link of the node instance applying the id and is stored in a node instance link set, and the design aims to obtain a complete interface controlled at the bottom layer;

the node plant abstraction uses a singleton mode at the same time, and the characteristic requirement of a global interface only has and only needs one node plant instance to exist, so that the feasible design is that the imaging method and the copy and copy method of the node plant abstraction are set to be private and a static member of which the type is the node plant is built in the abstraction, thereby preventing the abstraction from being randomly subjected to imaging and abuse; the static member is a component which belongs to the abstraction but does not belong to the example born by the abstraction, can only be initialized outside the main program and has uniqueness, and is connected with the unique node workshop example through the static interface of the node workshop abstraction, so that the node workshop abstraction is ensured to have only one example.

In step 1, the abstract design of the basic physical entity unit satellite node is mapped by a physical entity satellite node of a simulation scene: the simulation scene is an imaginary scene which is researched for simulating a large amount of satellite environments which may appear in reality;

the physical entity is a simulation individual which replaces a real object with the same name in a simulation scene and has a real meaning;

the basic unit is a minimum physical entity set which forms a simulation scene and can be independently controlled, wherein a satellite scene refers to a single satellite;

the abstract design is a description method for the kind of real objects constructed by pertinently extracting common and essential features from the real objects and combining the common and essential features.

The mapping means that an instance generated by abstraction of the physical entity of the kind represents the physical entity in the simulation scene;

the instance is to complete the visualization processing through concrete data according to the abstraction designed according to the category characteristics, namely, one instance only represents a specific individual of which the type belongs to the abstraction;

the simulated transition of the real nodes to virtual instances includes the following logical processes:

physical reality is converted into a simulation scene through reality investigation, target setting and experimental design, wherein real nodes are converted into physical entities;

the simulation scene is converted into various abstractions by extracting common and essential characteristics according to types and combining with a reconstruction process, wherein the characteristics of a certain physical entity are described by a certain abstract;

the abstraction is characterized as an instance of a particular individual through actual parameter settings, where some abstract description is ultimately characterized as a virtual instance.

The abstract design of the satellite constellation in step 2 includes satellite constellation information, links to all contained satellite instances, a satellite constellation initialization method, and a satellite motion algorithm designed for simplified operation, that is, the abstract design includes the following fields:

m _ orbitNumber, which represents the number of slanted tracks, i.e., P, for this constellation instance;

m _ satterOrbit, which represents the number of satellites in each orbit of the constellation instance, namely T/P;

m _ phase, representing the phase factor for this constellation instance, i.e., F;

m _ satList, which represents the set of link data of all satellite instances contained in this constellation instance;

the m _ TAANOPCS represents the elevation angles of all satellite instances contained in the constellation instance, is used for storing and describing the positions of the satellites in the inclined orbit plane, and is convenient for large-scale operation;

m _ inclination, which represents the orbital dip of the constellation;

m _ estimate, representing the orbital height of the constellation;

m _ seed RAAN, which represents the ascent point right ascension of the seed satellite;

the ascent point right ascension refers to the included angle between the ascent point radial direction and the spring minute point radial direction formed by the intersection of the included angle between the orbit where the seed satellite is located and the equatorial plane;

the elevation angle refers to an included angle between an elevation intersection radial and a satellite position radial in an inclined orbit plane of the satellite along the satellite running direction, the radial direction refers to a connection line between the radial direction and the earth center, and the consideration here is a perfect circular orbit, so that no orbit near place exists, and the elevation intersection is used as a reference point of the satellite orbit; the seed satellite is a satellite node example which provides data including orbit height, orbit inclination, elevation intersection point right ascension, elevation angle and the like for constructing the Walker-delta constellation, and the data can be obtained by analyzing the seed satellite example or can be directly input to the constellation example from the outside;

the links of all the contained satellite instances refer to a data set which records the links of all the satellite nodes in the constellation and can be quickly inquired; the satellite constellation initialization method is that data of all satellites in a satellite constellation are calculated according to seed satellite data and constellation data, and the data are used for rendering the abstract type of satellite nodes, namely all satellite node instances of the constellation are constructed and links are recorded;

the satellite constellation information comprises constellation type information and is classified according to the constellation type information, a satellite constellation initialization method is adopted, the default constellation type is a Walker-delta constellation, parameters contained in a Walker-delta constellation model are T, P, F, h and theta, T represents the total satellite number in the constellation, P represents the orbital plane number in the constellation, theta represents the constellation orbital inclination angle, h represents the constellation altitude, F represents the phase factor of orbital distribution, and the value range is an integer from 1 to T/P-1; the meaning of the phase factor F is that in a Walker-delta constellation, when a certain satellite in an orbit reaches an ascending point, the ascending point angle of the numbered satellite in the same orbit on the adjacent orbit on the right side is F.2 pi/T;

in the Walker-delta constellation initialization method in the step 2, input parameters are a rising point right ascension setraan of a seed satellite orbit, a rising point angle settaan of the seed satellite, a height h of the seed satellite orbit, an inclination angle theta of the seed satellite orbit, a tilt orbit number P of a constellation, a satellite number T/P of each orbit of the constellation and a phase factor F of the constellation;

the initialization method is divided into two major steps:

step 2-a: the elevation angles of all satellites were calculated and recorded:

step 2-a-1: according to the definition of the phase factor F, when a certain satellite in the orbit reaches the elevation point, the latitude argument from the elevation point, i.e. the elevation point angle, of one satellite on the right adjacent orbit to the elevation point is F · 2 Π/T, and the following formula is provided:

wherein TAAN_iThe elevation angle of the satellite with the ith track number of 1 is indicated;

step 2-a-2: the Walker-delta constellation is uniformly distributed in the orbit, bisecting radians of 2 pi, and therefore has the following formula:

wherein TAAN_ijThe elevation angle of a satellite numbered j in the ith orbit is pointed;

step 2-a-3: all TAANs are connected_ijSequentially storing the data in m _ TAANOPCS, wherein OPCS refers to a track plane polar coordinate system;

step 2-b: and (3) independently calculating the position of each satellite in the geocentric geostationary coordinate system and the geocentric geostationary polar coordinate system according to the elevation angle and other parameters:

step 2-b-1, the formula of the satellite instance coordinate converted from the OPCS coordinate system to the orbital plane rectangular coordinate system is as follows:

the orbit plane rectangular coordinate system takes the elevation point radial direction as an x axis, the y axis is radially superposed with the elevation point angle by 90 degrees, and the z axis is perpendicular to the orbit plane and forms a right-hand rectangular coordinate system with the x axis and the y axis;

step 2-b-2, the formula of the satellite example coordinate converted from the orbit plane rectangular coordinate system to the earth-centered earth-fixed rectangular coordinate system (ECEF) is as follows:

wherein x, y and z are three-dimensional coordinates of an ECEF coordinate system, and the origin of the coordinates of the coordinate system is located at the geocenter; the X axis points to the intersection point of the reference meridian plane and the equator of the earth; the Z axis is coincident with the earth rotation axis and points to the earth north pole; the Y axis is positioned in an equatorial plane, is vertical to the X axis and forms a right-hand rectangular coordinate system with the X, Z axis;

where θ is the inclination of the orbit, Ω is the ascension of the intersection point of the orbit of the satellite example, and the formula of Ω is as follows:

wherein omega_iDenotes the rising cross-point right ascension, Ω, of the ith track_seedThe rising point right ascension of the orbit of the seed satellite, namely the 1 st orbit is represented;

step 2-b-3, the formula of the example satellite coordinate converted from the ECEF coordinate system to the earth-centered earth-fixed polar coordinate system (LLA) is as follows:

wherein lon, lat and alt respectively represent longitude, latitude and altitude in LLA coordinate system, and R represents earth average radius;

and 2-b-4, imaging the abstract of the satellite node according to the calculated longitude, latitude and altitude data to generate a satellite node instance, binding the logical position of the satellite node instance with an instance link, and recording the satellite node instance in an m _ satList.

The running method of the Walker-delta constellation in the step 2 can be used only after the constellation is initialized, the parameters needing to be input are data for storing all satellite elevation angles, m _ TAANOPCS and running time, the running time represents the total time of simulation scene advancing, the parameter which can be additionally input is resolution accuracy, the resolution represents the step length of time advancing, and the default is the same as the time;

the operation method mainly comprises three steps:

step 2-c: calculating and updating the elevation angles of all satellites;

step 2-c-1: assuming that the earth is a standard sphere, under the condition of not considering the interference of factors such as the revolution of the earth, atmospheric perturbation and the like, the orbit of the satellite can be approximate to a circular orbit, and can be obtained according to the Keplerian third law:

wherein G is gravity constant, M is earth mass in kilogram, and R_sThe radius of the satellite orbit is given as meter, omega is the satellite running angular velocity and is given as rad/s;

step 2-c-2: the following formula can be applied to the elevation angles of all satellites:

TAAN_ij′＝TAAN_ij+t·ω(mod2Π)

wherein TAAN_ij' represents the result of the change of the satellite number (i, j) after the lapse of time t;

step 2-d: because the right ascension at the ascending intersection point is changed under the influence of the rotation of the earth, calculating the new ascending intersection point right ascension of the seed satellite:

wherein omega_seed' denotes the rising point right ascension of the seed satellite after the change of time t,

representing the rotational angular velocity of the earth;

step 2-e: and (4) independently calculating the position of each satellite in the geocentric geostationary coordinate system and the geocentric geostationary polar coordinate system according to the elevation angle and other parameters, wherein the step is completely the same as the step 2-b, and the step 2-b procedure is multiplexed.

In step 2, the abstraction of the final simulation scene comprises the links of all constellation instances and operation method interfaces;

the link of all constellation instances is a data set which records the link of all constellation instances in the simulation scene and can be quickly inquired;

the operation method interface refers to an interface for uniformly calling the operation method of the constellation instance, which is provided for facilitating the uniform management of all constellations in the simulation scene by a user;

further, the simulation scene abstract design in step 2 includes links to all constellation instances included and an operation method interface, that is, the following fields:

the simulation scene abstraction contains the following fields:

m _ constellation scenes, representing the set of data linked by all constellation instances contained in this simulation scenario instance.

In step 3, the database storage interface abstract comprises a database connection method, a database insertion method, a database query method and a database deletion method;

the database connection method is a method for directly establishing connection with a local or remote host through parameters such as host addresses, user names, passwords, ports and the like after being packaged, and is a necessary step for calling all subsequent database methods;

the database insertion method is a method which is packaged and can store data into the database according to a preset structure;

the database query method refers to a method for searching corresponding information in a database according to indexes after packaging;

the database deleting method is a method for deleting corresponding information in the database according to the index after packaging;

the database, the structural design contains the following parts:

id, representing the unique identification of the satellite node where the piece of data is stored;

longtitude, which represents the longitude of the satellite node where this piece of data is stored;

latitude, which represents the Latitude of the satellite node stored in the piece of data;

altitude, which represents the Altitude of the satellite node stored in the data;

time, which represents the simulation Time of the satellite node stored in the data;

constellation, which represents the satellite Constellation name of the satellite node stored in the data.

The links of all constellation instances are recorded, namely, a data set which can be quickly inquired and is linked with all constellation instances in the simulation scene is recorded;

the operation method interface is an interface for uniformly calling the operation method of the constellation instance, which is provided for facilitating the uniform management of all constellations in the simulation scene by a user.

Step 3, abstract design of database storage, including data structure design, database connection method, database insertion method, database query method and database deletion method, namely, the following parts are included:

the database connection method is a method which is packaged and can directly establish connection with a local or remote host through parameters such as host addresses, user names, passwords, ports and the like, and is also a necessary step for calling all subsequent database methods;

the database query method is a method which is packaged and can search corresponding information in the database according to the index;

the database deleting method is a method which is packaged and can delete corresponding information in the database according to the index;

the data structure design contains the following fields:

Further, in step 3, the simulation main program comprises components of module carrying, simulation scene building, database connection and simulation operation;

the module loading means that the connection is established with all the abstract types before through a precompilation command, and all the components of the simulation architecture are fused together;

building the simulation scene, namely building and initializing the satellite simulation scene required by the experiment by using a satellite node abstraction, a satellite constellation abstraction and a simulation scene abstraction building example;

the database connection refers to connecting the database by using parameters such as host addresses, user names, passwords, ports and the like and performing data entry arrangement;

the simulation operation refers to calling a simulation operation method through an interface of a simulation scene instance, changing simulation time of the simulation scene, and acquiring data of the satellite node instance changing along with the change of the simulation time.

Has the advantages that: the method of the invention provides a lightweight programming architecture design that can be used to simulate ultra-dense large-scale satellite scenarios based on personal computer equipment. The complete decoupling with the mainstream simulation software ensures that the invention does not depend on external programs and can freely change the customization aiming at the experimental object; the lightweight design greatly reduces the cost required by the simulation of the satellite nodes, and facilitates the realization of the simulation of satellite constellations at ten thousand levels; the modular design which accords with the practical logic and has a clear structure ensures that the invention has enough expandability and is convenient to realize. Compared with the existing large-scale scene software simulation scheme, the design architecture method is completely decoupled from the existing mainstream commercial simulation software, the light-weight design enables the realization of the ultra-large-scale simulation scene, and the modular architecture enables the functions of the simulation scene to meet the personalized customization requirements and is more convenient for the follow-up work of adding, deleting and correcting.

Drawings

FIG. 1 is a scene diagram of a very large scale low earth orbit satellite constellation employed in an embodiment of the present invention;

FIG. 2 is a flow chart of an implementation of a lightweight simulation architecture design method employed by the present invention;

FIG. 3 is a schematic diagram of a Walker-delta constellation initialization construction method and a simulation operation method for simplifying operations according to the present invention;

FIG. 4 shows the main interaction relationships between abstract types constructed according to the simulation architecture design method of the present invention;

FIG. 5 is a feedback that may be obtained by the present invention querying a database using a random unique identification.

Fig. 6 is a simulation structure of a light simulation architecture design method for a super-dense large-scale satellite scene, which is performed by using 11927 satellites as objects in a Starlink low-earth orbit satellite constellation.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in detail below with reference to the accompanying drawings: the embodiment is implemented on the premise of the technical scheme of the invention, and a detailed implementation mode and a specific operation process are given. It should be understood that the specific examples described herein are merely illustrative of the invention and that the scope of the invention is not limited to the examples described below.

In this embodiment, a ten thousand level low earth orbit satellite constellation simulation scene imitating a Starlink complete constellation as an object shown in fig. 1 is adopted. Firstly, the relevant conditions of the low-orbit satellites in the scene are introduced:

according to Starlink data, 11927 satellites are co-deployed in a simulation scene and divided into 8 Walker constellation orbital planes, and the orbital altitude is 350-1350 kilometers.

FIG. 2 is a flowchart of a design method of a lightweight simulation architecture for an ultra-dense large-scale satellite scenario according to an embodiment of the present invention. Which comprises 3 steps.

Step 1: minimum cell design is performed. The minimum unit design comprises the abstraction of a satellite node of a design basic physical entity unit and the simulation control abstraction NodeFactory type of an auxiliary management scene entity.

Step 2: and building a satellite scene logical structure. The building of the satellite scene logic structure comprises the design of a satellite constellation and the abstraction of a final simulation scene.

And step 3: simulation is started and external interaction is performed. The simulation and interaction includes design database storage interface abstraction and simulation main program. Designing a final Simulation scene abstract Simulation type formed by combining a plurality of constellations facing a user, and packaging a common method and a bottom layer interface for facilitating large-scale satellite Simulation; designing an interface abstract DataBase type for managing DataBase reading and writing, and storing the reading and writing in real time according to research requirements; and compiling a main script according to the abstract type for simulation.

The abstract design of the satellite node in the step 1 is formed by pertinently extracting common and essential characteristics of a real satellite according to an experimental purpose and combining and reconstructing, and according to the particularity of the simulation scene example, the abstract design comprises the following fields:

m _ name, which represents the name of the satellite instance, is not unique, but may contain logical location information.

In the abstract design of the node workshop in the step 1, a singleton mode is used for maintaining simulation scene time and distributing a unique identity identifier to each satellite node instance, and according to the particularity of the simulation scene instance, a management object comprises the generation of the simulation scene time, a satellite node instance link set and the unique identity identifier:

the simulation scene time is used for recording the whole simulation scene time of physical entity motion change along with time change after the simulation scene time is established, and the simulation scene time is a unique time mark which needs to be synchronously modified when the time described by the simulation scene changes;

the unique identification represents a unique identity of the satellite node instance in the simulation scene, and the satellite instance link can be quickly searched through the satellite instance link set according to the unique identification so as to query satellite data;

the generation of the unique identification mark is shown in the design of the satellite node abstraction, when the satellite node abstraction is embodied into an instance, the unique identification mark m _ id needs to be applied to a node plant instance, in the process, the node plant instance returns an unassigned id value, the id value is bound with a link of the node instance applied to the id and is stored in a node instance link set, and the design aims to obtain a complete interface controlled at the bottom layer;

the node plant abstraction needs to use a singleton mode, the characteristic requirement of the global interface can only exist and only needs one node plant instance to exist, therefore, the feasible design is to set the visualization method and the copy and copy method of the node plant abstraction as private and to embed a type as a static member of the node plant in the abstraction, thereby preventing the abstraction from being randomly visualized and abused.

In step 2, the abstract design of the satellite constellation includes, according to the particularity of the simulation scene instance, satellite constellation information, links to all contained satellite instances, a satellite constellation initialization method, and a satellite motion algorithm designed for simplified operation, that is, the following fields:

m _ name, which represents the name of the constellation instance, is non-unique, is used for searching according to the name and storing and searching in a database, is set when the constellation instance is embodied, and is empty by default;

m _ orbitNumber, which represents the number of slanted tracks for this constellation instance;

m _ satterorbit, which represents the number of satellites in each orbit of the constellation instance;

m _ phase, representing the phase factor of this constellation instance;

m _ inclination, which represents the orbital dip of the constellation;

m _ estimate, representing the orbital height of the constellation;

m _ seed RAAN, which represents the ascent point right ascension of the seed satellite.

According to the satellite constellation initialization method, the default constellation type is a Walker-delta constellation, and parameters contained in a Walker-delta constellation model are T/P/F: h: theta, T represents the total number of satellites in the constellation, P represents the number of orbital planes in the constellation, theta represents the inclination angle of the orbits of the constellation, h represents the altitude of the constellation, F represents the phase factor of orbital distribution, and the value range is an integer from 1 to T/P-1;

fig. 3 is a schematic diagram of a Walker-delta constellation initialization construction method and a simulation operation method of the lightweight simulation architecture design method for an ultra-dense large-scale satellite scene according to the embodiment of the invention, and the specific steps are as follows:

step 2-a: the elevation angles of all satellites were calculated and recorded:

wherein, the lifting point angle of the satellite with the ith track number of 1 is indicated;

step 2-a-3: storing all the data in m _ TAANOPCS according to the sequence, wherein OPCS refers to a track plane polar coordinate system;

the right ascension at the ascending intersection point of the ith orbit is shown, and the right ascension at the ascending intersection point of the 1 st orbit is shown;

The satellite motion algorithm is divided into three steps:

step 2-c: calculating and updating the elevation angles of all satellites;

wherein G is a gravitational constant, M is the earth mass in kilograms, Rs is the radius of the satellite orbit in meters, and omega is the satellite running angular velocity in rad/s;

TAAN_ij′＝TAAN_ij+t·ω(mod2Π)

wherein omega_seed' indicates after the lapse of time tThe right ascension of the seed satellite of (1),

representing the rotational angular velocity of the earth;

The abstract design of the simulation scene in the step 2 comprises the links of all constellation instances and operation method interfaces according to the particularity of the simulation scene instance, namely the following fields:

m _ constellation scenes, representing the data set linked by all constellation instances contained in the simulation scene instance;

In step 3, the database stores abstract design, and includes a data structure design, a database connection method, a database insertion method and a database query method according to the particularity of the simulation scene instance, namely, the method includes the following parts:

the data structure design contains the following fields:

The simulation main program in the step 3 comprises the components of module carrying, simulation scene building, database connection and simulation operation;

the module carrying is to establish connection with all previous abstract types through a precompilation command and fuse all the constituent modules of the simulation architecture together;

the simulation scene building is to build a satellite constellation example by using satellite node abstraction, satellite constellation abstraction and simulation scene abstraction, and build and initialize a satellite simulation scene required by a simulation experiment;

the database connection is that the database is connected by keying in parameters such as host address, user name, password, port and the like and data entry arrangement is carried out;

the simulation operation is to call a simulation operation method through an interface of a simulation scene example, change the simulation time of the simulation scene, and acquire data of the satellite node example changing along with the change of the simulation time.

Fig. 4 shows the main interaction relationship between abstract types established according to the simulation architecture design method in the embodiment of the present invention, which represents the operation mode of the simulation architecture, and satisfies the design requirement for performing ultra-dense large-scale satellite scene simulation while maintaining a compact lightweight architecture.

Aiming at the Starlink constellation object researched by the example, in order to perform track simulation and data storage of ten thousand-level ultra-dense large-scale satellite scenes, the simulation target is realized by calling the following interface method in a simulation main program:

step 1: and loading the NodeFactory type, the Node type, the configuration type, the Simulation type and the DataBase type by using a module loading function.

Step 2: creating a DataBase type example, calling a DataBase connection method, and completing DataBase connection through a host address, a user name, a password and port parameters.

Step 2: and calling a Constellation type quick construction method to realize quick construction of a satellite network logic structure, and quickly constructing 8 Constellation instances according to Starlink Constellation parameters. In the construction process, a satellite constellation initialization method has been used to generate a plurality of Node type instances which form the constellation and represent satellite nodes, and the Node type instances access the unique instances of the Node factory type to obtain the unique identification of the Node type instances.

And step 3: creating a Simulation type instance, and adding 8 Constellation instances into the Simulation type instance through a built-in Constellation addition method interface.

And 4, step 4: the Simulation run method of the Simulation type instance is called, and a Simulation scene runs for 10 seconds by using the parameter 7. When the Simulation operation method of the Simulation type instance is called, the Simulation operation methods of all Constellation instances under the instance are triggered, each satellite Constellation instance calculates the new coordinate positions of all satellite node instances under the satellite Constellation instance independently, and the m _ currentPosition information contained in all satellite node instances under the satellite Constellation instance is updated. The position updating method calls a DataBase insertion method of a DataBase type example while updating information, and writes the unique identification m _ id of the satellite example, the coordinate position information m _ currentPosition, the simulation scene time and the name m _ name belonging to the Constellation example into the DataBase.

And 5: this operation was performed 6 times by repeating step 4 but changing the parameters of the simulation run method to 10.

Step 6: and calling a resource release method interface of the Simulation type example, and ending the Simulation.

Querying the database with a random unique identification may result in feedback as shown in fig. 5, proving that the data is accurately stored in the database.

As shown in fig. 5, the database selected for connection in this example is a MySQL database, which is a mature relational database management system that stores data in different tables. According to the composition of a data structure needing to be saved, a table named satellite is created in a MySQL database, the table is composed of 6 partitions, the partitions are id, longtitude, latitude, height, time and Constellations respectively, the storage types are int, double, int and int respectively, the unique identification of a satellite instance represented by the piece of storage data (namely m _ id of the satellite instance), the longitude value, the latitude value, the altitude (unit kilometer) (namely the content of m _ currentPoint) of a coordinate (a geocoordinate system) of the instance at the simulation time, the simulation scene time (a unit of seconds) and the name of a constellation to which the satellite instance belongs (namely m _ name of the constellation instance) are represented respectively. By the DataBase connection method of the DataBase type, a host address, a user name, a password and port parameters can be used for being connected with the DataBase in the lightweight simulation program, when the simulation operation method is used, a DataBase insertion method is automatically called, and when position coordinates of all satellite instances are updated, new coordinate information and related data are stored according to the structure of a table created in the DataBase.

The user can directly search the relevant information in the main simulation script by using a database reading method through connection, and can also directly query by using a database operation method at a database end. After logging in the database, using the instruction select from the table named satellite 213 in fig. 5, the data with the value of all id partitions equal to 213 can be looked up in the table named satellite and displayed, or other various query methods can be used. The result shown in fig. 5 is thus obtained, which corresponds to the master script operating logic, for a total of 6 data items representing the position coordinates of the satellite instance uniquely identified with 213, with its name of constellation instance 1, at the time of

simulation time

7, 17, 27, 37, 47, 57.

All data with the simulation time of 7 in the database are extracted and are led into Matlab mathematical analysis software, and a visual graph can be obtained in a 3-dimensional coordinate system, as shown in FIG. 6, and the simulated ultra-dense multi-layer low-orbit satellite constellation characteristics are met.

And (3) reading all data with the simulation time of 7 (namely the time partition value is equal to 7) by using a database reading method in the simulation master script, extracting the position coordinates of the data, storing the position coordinates into a text file, and reading by using Matlab. The reason for using Matlab is that the design does not carry a real-time visualization module in order to realize a lightweight simulation architecture. In Matlab, the earth centroid is fixed at a coordinate point of (0,0,0), the earth radius uses 6371 kilometer, and longitude, latitude and altitude data based on a geodetic coordinate system are converted into a three-dimensional rectangular coordinate system, namely the inverse process of the step 2-b-3 is adopted. Finally, using the plot3 command of Matlab, and taking the converted x, y, z data as parameters, a three-dimensional scene result as shown in fig. 6 is drawn.

It can be seen that the distribution of x, y and z data in three coordinate axis directions is about-8000 to 8000, and the data is a perfect sphere in numerical view. The sphere in the figure is composed of 11927 points, and the part of the figure that looks like a circular curve is also composed of dense points. Fig. 6 is a three-dimensional visual display of coordinate information of all satellite instances in the simulation scene at a certain simulation time, which is performed by the design method of the ultra-dense large-scale satellite scene lightweight simulation architecture, and which takes 11927 satellites as objects in the Starlink low-earth orbit satellite constellation, and conforms to the constellation system characteristics.

The invention provides a design method of a lightweight simulation architecture for an ultra-dense large-scale satellite scene, and a plurality of methods and ways for implementing the technical scheme are provided, the above description is only a preferred embodiment of the invention, and it should be noted that, for a person skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the invention, and these improvements and decorations should also be regarded as the protection scope of the invention. All the components not specified in the present embodiment can be realized by the prior art.

Claims

1. A design method of a lightweight simulation architecture for an ultra-dense large-scale satellite scene is characterized by comprising the following steps: a design method of a lightweight simulation architecture facing an ultra-dense large-scale satellite scene is characterized in that a simulation control abstract NodeFactory type of an auxiliary management scene entity is designed, a single-case mode is used for maintaining unique time and distributing a unique identity to each satellite node case; the method comprises the following steps: step 1, designing an abstract Node type of a satellite Node with a minimum physical unit, representing an actual satellite in a simulation scene as a simulation base stone, and storing satellite related parameters; step 2, designing a single-layer Constellation abstract Constellation type formed by logically combining satellite nodes, wherein the single-layer Constellation abstract Constellation type comprises Constellation composition parameters, satellite links and Constellation motion simplification; step 3, designing a final Simulation scene abstract Simulation type formed by combining a plurality of constellations facing a user, and packaging a common method and a bottom layer interface for facilitating large-scale satellite Simulation; designing an interface abstract DataBase type for managing DataBase reading and writing, and storing the reading and writing in real time according to research requirements; and compiling a main script according to the abstract type for simulation.

2. The method according to claim 1, characterized by the following specific steps, step 1, minimum unit design: the minimum unit design comprises the abstraction of a satellite node of a basic physical entity unit and the abstraction of a node workshop of an auxiliary management scene entity; the abstract design of the satellite node comprises a simulation target requirement including but not limited to a node unique identification number, a three-dimensional coordinate of a geocentric earth fixed polar coordinate system, an operation orbit parameter, a constellation information and a satellite name, and the abstract of the node workshop uses a singleton mode to maintain simulation scene time and distributes a unique identity to each satellite node instance;

included among these must be the following fields:

In step 1, the abstract design of the basic physical entity unit satellite node is mapped by a physical entity satellite node of a simulation scene:

the simulation scene is an imaginary scene which is researched for simulating a large amount of satellite environments which may appear in reality;

3. The method of claim 1,

m _ inclination, which represents the orbital dip of the constellation;

m _ estimate, representing the orbital height of the constellation;

the ascension point right ascension refers to an included angle between the ascension point radial direction and the spring minute point radial direction formed by the intersection of the track where the seed satellite is located and the included angle of the equatorial plane;

the elevation angle refers to an included angle between an elevation intersection radial and a satellite position radial in an inclined orbit plane of the satellite along the satellite running direction, the radial direction refers to a connection line between the radial direction and the earth center, and the consideration here is a perfect circular orbit, so that no orbit near place exists, and the elevation intersection is used as a reference point of the satellite orbit;

the seed satellite is a satellite node example which provides data including orbit height, orbit inclination, elevation intersection point right ascension, elevation angle and the like for constructing the Walker-delta constellation, and the data can be obtained by analyzing the seed satellite example or can be directly input to the constellation example from the outside;

the links of all the contained satellite instances refer to a data set which records the links of all the satellite nodes in the constellation and can be quickly inquired;

the satellite constellation initialization method is that data of all satellites in a satellite constellation are calculated according to seed satellite data and constellation data, and the data are used for rendering the abstract type of satellite nodes, namely all satellite node instances of the constellation are constructed and links are recorded;

the initialization method is divided into two major steps:

step 2-a: the elevation angles of all satellites were calculated and recorded:

the operation method mainly comprises three steps:

step 2-c: calculating and updating the elevation angles of all satellites;

TAAN_ij′＝TAAN_ij+t·ω (mod 2Π)

representing the rotational angular velocity of the earth;

the abstract design of the simulation scene in the step 2 comprises links of all constellation instances and operation method interfaces, namely the following fields:

the simulation scene abstraction contains the following fields:

4. The method according to claim 1, wherein in step 3, the database storage interface abstraction comprises a database connection method, a database insertion method, a database query method, and a database deletion method;

the database, the structural design contains the following parts:

the data structure design contains the following fields:

In step 3, the simulation main program comprises the components of module carrying, simulation scene building, database connection and simulation operation;

5. The method of claim 1, wherein the following fields are added at emulation time:

and the m _ linkMessage represents the inter-satellite link connection logical relationship of the satellite and is used for describing the formation form of inter-satellite networking in specific constellation design.