Giant satellite base partition centralized orbit determination and time synchronization method and system under support of inter-satellite measurement

Abstract

The invention discloses a giant astronomical base partition centralized orbit determination and time synchronization method and system under the support of inter-satellite measurement, and relates to the field of giant astronomical bases, and the method comprises the steps: carrying out the space partitioning of all satellites in a giant astronomical base through employing a specific topological configuration, and obtaining a plurality of regional grids; node satellites in the current regional grid perform centralized Kalman filtering measurement updating by using all observation data to obtain a first updating result; sending the first updating result to each satellite in the current regional grid, and controlling each satellite to perform distributed Kalman filtering time updating to obtain a second updating result; the second updating result is sent to the node satellites in the current regional grid; and controlling the node satellites in the current regional grid to send all the received second update results to the node satellites in the adjacent regional grid, and repeating the steps to complete orbit determination and time synchronization of satellites of multiple batches. According to the invention, precise orbit determination and time synchronization of satellites in a giant satellite base are realized.

Description

Technical Field

[0001] The present application relates to the field of giant star constellation technology, and in particular to a method and system for centralized orbit determination and time synchronization of giant star constellations supported by inter-satellite measurements. Background Art

[0002] With the emergence of low-orbit communication satellites represented by STARLINK and ONEWEB, the development of low-orbit giant satellites has gradually started. At present, the satellite systems of most countries usually have more than 500 giant satellites. In addition to communication functions, the giant satellite also has navigation and positioning functions, so it has high requirements for the accuracy and real-time performance of satellite orbits and clock errors.

[0003] The determination of the satellite's precise orbit and clock error is a prerequisite for the satellite to complete specific tasks. There are currently two main ways to determine the satellite's orbit and clock error. One is to use ground station satellite-to-ground or inter-satellite observations to determine them through centralized ground processing. The other is to use onboard GNSS observations, with the help of known GNSS orbit and clock error information, and use onboard data processing methods to enable each satellite to autonomously determine its orbit and clock error in orbit. Among them, autonomous orbit determination based on inter-satellite measurements and onboard data processing needs to take into account both the onboard data processing storage capacity and the feasibility of accuracy indicators. The traditional ground processing uses a large amount of data processing computation for the centralized optimal estimation algorithm for the entire network, which is usually difficult to copy. Although the navigation satellite system adopts a suboptimal single-satellite distributed processing method and successfully solves the problem of autonomous determination of the precise orbit and clock error of the navigation satellite under the support of inter-satellite links, the single-satellite distributed processing method adopted by the navigation satellite system has strong requirements on the number and reliability of link establishment for each satellite. For low-orbit Giant Star satellites that need to take into account communication and navigation functions, the above-mentioned measurement link requirements are difficult to meet on a large scale throughout the entire period of time. If the Giant Star satellite completely adopts the single-satellite distributed processing method, it will cause the orbit determination and time synchronization accuracy of some satellites to be difficult to stably meet the requirements.

[0004] Based on the above analysis, when there are a large number of satellites in the Giant Star constellation or the GNSS navigation signal is interfered with, the above methods cannot meet the needs of precise orbit and clock error determination of satellites in the Giant Star constellation. Summary of the invention

[0005] The purpose of this application is to provide a method and system for centralized orbit determination and time synchronization in the Giant Star constellation supported by inter-satellite measurement, so as to realize precise orbit determination and time synchronization of satellites in the Giant Star constellation.

[0006] To achieve the above objectives, this application provides the following solutions:

[0007] In a first aspect, the present application provides a method for centralized orbit determination and time synchronization in a Giant Star constellation partition supported by inter-satellite measurement, wherein the method comprises:

[0008] According to the pre-designed intersatellite link building strategy, intersatellite links for mutual transmission and reception between different satellites in the giant star constellation are constructed; each satellite in the giant star constellation is equipped with laser or microwave intersatellite measurement and communication equipment;

[0009] Control each satellite in the giant star constellation to periodically acquire two-way inter-satellite ranging data with the corresponding link-building satellite, as well as orbital parameters, clock error parameters and parameter covariance of the corresponding link-building satellite;

[0010] Controlling each satellite in the giant star constellation to perform system error correction on the received two-way inter-satellite ranging data, and performing measurement time normalization and signal propagation path correction on the two-way inter-satellite ranging data after the system error correction, so as to obtain instantaneous inter-satellite observation amount;

[0011] Based on the intersatellite link establishment strategy, a specific topological configuration is used to spatially partition all satellites in the giant star constellation to obtain multiple regional grids, and node satellites in each of the regional grids are determined; multiple intersatellite links exist between different satellites in the same regional grid; and multiple intersatellite links also exist between adjacent regional grids;

[0012] For each of the regional grids, the following steps are performed synchronously:

[0013] Send all observation data to the node satellites in the current regional grid; the all observation data include: instantaneous inter-satellite observation quantities between all satellites in the current regional grid, instantaneous inter-satellite observation quantities between each satellite in the current regional grid and the corresponding satellites in the built-in chain of adjacent regional grids, and orbit parameters, clock error parameters and parameter covariance of satellites in the built-in chain of adjacent regional grids corresponding to each satellite in the current regional grid; the current regional grid is any one of the multiple regional grids;

[0014] Control the node satellites in the current regional grid to perform centralized Kalman filter measurement update using all the observation data to obtain a first update result; the first update result includes: orbit parameters, clock error parameters and parameter covariance of all satellites in the current regional grid after the filter measurement update;

[0015] The first update result is sent to each satellite in the current regional grid through different intersatellite links, and each satellite is controlled to use the corresponding orbit and clock error dynamics model and adopt a numerical integration method to perform distributed Kalman filter time update to obtain a second update result, and the second update result is sent to the node satellite in the current regional grid; the second update result includes: the orbit parameters, clock error parameters and parameter covariance of the corresponding satellite in the current regional grid after the filter time is updated;

[0016] Control the node satellites in the current regional grid to send all received second update results to the node satellites in the adjacent regional grids, so as to complete the satellite orbit determination and time synchronization of a single batch;

[0017] After all satellites in the giant star constellation have completed orbit determination and time synchronization for a single batch, the above steps are repeated for each regional grid to continuously perform orbit determination and time synchronization for multiple batches of satellites.

[0018] In a second aspect, the present application also provides a computer system, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for centralized orbit determination and time synchronization of supergiant constellation partitions supported by intersatellite measurements as described in the first aspect.

[0019] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0020] First, according to the intersatellite link building strategy, this application uses a specific topological configuration to spatially partition all satellites in the Giant Star constellation. At the same time, considering the characteristics of more satellite links between different regional grids, a centralized processing method is adopted to effectively utilize the indirect correlation between different intersatellite links, solving the problem of reduced accuracy caused by insufficient number of satellite links. Secondly, this application distributes the Kalman filter time update, which has a relatively large amount of computation but is suitable for parallel computing, to each satellite for processing. By appropriately controlling the partition scale of different regional grids, the number of orbital parameters and clock error parameters to be solved is reduced, and the data processing computation of centralized Kalman filter measurement update is reduced, which is convenient for on-board autonomous processing. Finally, this application also uses the interactive transmission of orbital parameters, clock error parameters and parameter covariance of node satellites between different regional grids to realize the information association of satellite parameter covariance of the whole network, which is conducive to improving the estimation accuracy of orbital parameters and clock error parameters of satellites in the whole network. Therefore, this application realizes precise orbit determination and time synchronization of satellites in the Giant Star constellation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] Figure 1 A flowchart of a method for centralized orbit determination and time synchronization of giant star constellations supported by intersatellite measurements provided in an embodiment of the present application;

[0023] Figure 2 A schematic diagram of the spatial partitioning of all satellites in the Giant Star constellation provided in an embodiment of the present application;

[0024] Figure 3 A schematic diagram of the internal structure of a computer system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] The purpose of this application is to provide a method and system for centralized orbit determination and time synchronization in the Giant Star constellation supported by inter-satellite measurement, so as to realize precise orbit determination and time synchronization of satellites in the Giant Star constellation.

[0027] Most of the low-orbit giant satellites use communication and navigation as their core functions. For this purpose, they are usually equipped with laser or microwave intersatellite measurement and communication equipment (payloads), and have certain intersatellite measurement capabilities and strong intersatellite communication capabilities. This makes it possible to use intersatellite measurements and on-board data processing to autonomously update satellite orbit parameters and clock error parameters on orbit, and to achieve precise satellite orbit determination and time synchronization without GNSS support.

[0028] In order to make full use of the onboard processing capabilities of each satellite, while taking into account the characteristics of regional link building of low-orbit satellites and the accuracy advantages of centralized processing algorithms, the core idea of ​​this application is to disperse the onboard Kalman filter time update processing to each satellite, and divide all satellites in the giant star constellation into multiple regional grids according to a specific topological configuration. The satellites in each regional grid use a centralized Kalman filtering method to achieve measurement updates, and the unification of the space-time reference information of the entire network is achieved by exchanging orbital parameters, clock error parameters and parameter covariance between node satellites in adjacent regional grids.

[0029] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0030] Example 1

[0031] like Figure 1 As shown, this embodiment provides a method for centralized orbit determination and time synchronization in the Giant Star constellation partition supported by inter-satellite measurement, and the method for centralized orbit determination and time synchronization in the Giant Star constellation partition supported by inter-satellite measurement includes:

[0032] Step S1: According to the pre-designed intersatellite link establishment strategy, intersatellite links for mutual transmission and reception between different satellites in the Giant Star constellation are constructed; each satellite in the Giant Star constellation is equipped with laser or microwave intersatellite measurement and communication equipment (payload).

[0033] In this embodiment, the intersatellite link establishment strategy usually needs to be determined in advance based on the comprehensive constellation configuration, intersatellite link load characteristics, intersatellite relay communication requirements, intersatellite measurement requirements, etc., and is uploaded to each satellite. Among them, for the laser intersatellite link load, the link establishment method between the front and rear satellites on the same orbit and the link establishment method between adjacent satellites on different orbits is usually adopted; for the Ka intersatellite link load, the link establishment method between the satellite and the adjacent surrounding satellites is usually adopted in sequence.

[0034] Step S2: Control each satellite in the giant star constellation to regularly obtain two-way inter-satellite ranging data with the corresponding link-building satellite, as well as the orbital parameters, clock error parameters and parameter covariance (i.e., the covariance of the orbital parameters and clock error parameters) of the corresponding link-building satellite.

[0035] In this embodiment, each satellite in the Giant Star constellation is equipped with a satellite platform, on which time-frequency timekeeping devices such as atomic clocks and crystal oscillators are installed. Driven by the time-frequency signals of the devices, each satellite can regularly obtain two-way inter-satellite ranging data between itself and the link-building satellite, the orbital parameters of the link-building satellite, clock error parameters and parameter covariance and other information.

[0036] Step S3: Control each satellite in the giant star constellation to perform system error correction on the received two-way inter-satellite ranging data, and perform measurement time normalization and signal propagation path correction on the two-way inter-satellite ranging data after the system error correction to obtain instantaneous inter-satellite observation quantities.

[0037] In this embodiment, the system error correction includes: equipment receiving and transmitting delay error correction, relativistic error correction, antenna phase center error correction, tropospheric / ionosphere signal propagation delay error correction, etc. The two-way intersatellite ranging observation quantity after the system error correction is then normalized to the measurement time and the signal propagation path correction, so that the intersatellite link observation quantity of the entire constellation of satellites is normalized to the instantaneous intersatellite observation quantity at a specific time. The specific time can be determined according to the measurement plan of the intersatellite link, usually the middle time of a single measurement of the entire constellation is rounded. By using the planned combination of instantaneous intersatellite observation quantities, instantaneous intersatellite ranging observation quantities and instantaneous intersatellite time synchronization observation quantities can be obtained. The instantaneous intersatellite ranging observation quantity is used to determine the instantaneous intersatellite ranging residual and the two-way intersatellite distance, and the instantaneous intersatellite time synchronization observation quantity is used to determine the instantaneous intersatellite time residual.

[0038] Step S4: Based on the inter-satellite link establishment strategy, a specific topological configuration is used to spatially partition all satellites in the Giant Star constellation to obtain multiple regional grids, and the node satellites in each regional grid are determined; there are multiple inter-satellite links between different satellites in the same regional grid; there are also multiple inter-satellite links between adjacent regional grids.

[0039] like Figure 2 As shown, the specific topology configuration of this embodiment is a cellular space topology configuration. In the figure, each dotted circle represents a regional grid. Each regional grid does not overlap with each other. Each regional grid is composed of multiple adjacent satellites. The number of satellites in each regional grid is related to the floating-point computing capability of the onboard processor and the topology configuration of the intersatellite link. It is usually evenly distributed throughout the network, and each regional grid contains 6 to 20 satellites. The triangles in the dotted circle represent satellites that are linked to each other in the regional grid. P0 to P6 in the dotted circle represent node satellites in the regional grid. The lines between P0 to P6 represent intersatellite links between adjacent regional grids.

[0040] In addition, there are one or two node satellites in each regional grid; when there are two node satellites in each regional grid, any one of the two node satellites is selected as a backup satellite. In order to select node satellites, for any regional grid, the onboard data processing and storage capacity of each satellite in the regional grid is determined, the number of inter-satellite links between each satellite in the regional grid, and the number of inter-satellite links between each satellite in the regional grid and the satellites in the adjacent regional grid are counted; according to the onboard data processing and storage capacity of each satellite in the regional grid and the corresponding number of inter-satellite links, one or two satellites are selected from all the satellites in the regional grid as node satellites.

[0041] Furthermore, for each regional grid, the following steps are performed synchronously:

[0042] Step S5: Send all observation data to the node satellites in the current regional grid; all observation data include: instantaneous inter-satellite observation quantities between all satellites in the current regional grid, instantaneous inter-satellite observation quantities between each satellite in the current regional grid and the corresponding satellites in the built-in chain of adjacent regional grids, and orbital parameters, clock error parameters and parameter covariance of satellites in the built-in chain of adjacent regional grids corresponding to each satellite in the current regional grid; the current regional grid is any one of the multiple regional grids.

[0043] In this embodiment, the satellite orbit determination and time synchronization processing based on inter-satellite measurement in each regional grid adopts an extended Kalman filtering method, which includes two parts, namely Kalman filter measurement update and Kalman filter time update. Among them, the Kalman filter measurement update adopts a partitioned centralized processing method, which is completed on the node satellite in each regional grid, using all the observation data in the regional grid, and using two filters for precise orbit determination and precise time synchronization to process simultaneously. In the Kalman filter measurement update processing of each regional grid, the orbit parameters, clock error parameters and parameter covariance of the built-in chain satellites in the adjacent regional grids are predicted to the current batch processing using the processing results of the previous batch, and participate in the processing of the orbit parameters and clock error parameters of each satellite in the current regional grid, and are not solved as unknown parameters. The inter-satellite ranging information of satellites in adjacent regional grids also needs to consider the influence of the prediction errors of satellite orbit parameters and clock error parameters, and use equivalent ranging information.

[0044] Among them, the linearized observation equation of the intersatellite link between different satellites in the same regional grid is:

[0045] Δρ ij =H i X i -H j X j +ε ij ;

[0046]

[0047] In the formula, Δρ ij is the instantaneous inter-satellite ranging residual or instantaneous inter-satellite time residual between satellite i and satellite j in the current regional grid, X i is the orbit parameter or clock error parameter of satellite i in the current regional grid, X j is the orbit parameter or clock error parameter of satellite j in the current regional grid, H i For X i The corresponding design matrix, H j For X j The corresponding design matrix, ε ijis the random noise of the instantaneous inter-satellite ranging observation or the random noise of the instantaneous inter-satellite time synchronization observation between satellite i and satellite j in the current regional grid, are the coordinates x of satellite i in the current regional grid respectively. i The three components of are the coordinates x of satellite j in the current regional grid. j The three components of ij is the two-way inter-satellite distance between satellite i in the current regional grid and satellite j in the current regional grid.

[0048] The linearized observation equation of the intersatellite link between adjacent regional grids is:

[0049] Δρ i ' k =Δρ ik +H k 'X k ′=H i X i +ε i ' k ;

[0050]

[0051] In the formula, Δρ i ' k is the equivalent inter-satellite ranging residual or equivalent inter-satellite time residual between satellite i in the current regional grid and satellite k in the adjacent regional grid, Δρ ik is the instantaneous inter-satellite ranging residual or instantaneous inter-satellite time residual between satellite i in the current regional grid and satellite k in the adjacent regional grid, X k ′ is the orbit parameter or clock error parameter of satellite k in the adjacent regional grid (taken from the time update value of the previous epoch filter), H k ′ is X k ′ corresponds to the design matrix, ε i ' k is the random noise of the equivalent inter-satellite ranging observation or the equivalent inter-satellite time synchronization observation between satellite i in the current regional grid and satellite j in the adjacent regional grid, ε ik is the random noise of the instantaneous inter-satellite ranging observation or the random noise of the instantaneous inter-satellite time synchronization observation between satellite i in the current regional grid and satellite j in the adjacent regional grid, is the parameter covariance of satellite k in the adjacent regional grid.

[0052] For the linearized observation equations of the intersatellite links between the same regional grid / adjacent regional grids mentioned above, when using the ranging quantities such as the instantaneous intersatellite ranging residual, the instantaneous intersatellite ranging observation random noise, the equivalent intersatellite ranging residual, the equivalent intersatellite ranging observation random noise for calculation, the orbital parameters are solved; when using the time quantities such as the instantaneous intersatellite time residual, the instantaneous intersatellite time synchronization observation random noise, the equivalent intersatellite time residual, the equivalent intersatellite time synchronization observation random noise for calculation, the clock error parameters are solved.

[0053] Step S6: Control the node satellites in the current regional grid to use all observation data to perform centralized Kalman filter measurement update to obtain a first update result; the first update result includes: orbit parameters, clock error parameters and parameter covariance of all satellites in the current regional grid after the filter measurement update.

[0054] The calculation formula for the first update result is:

[0055]

[0056] In the formula, The orbit parameters or clock error parameters of all satellites in the current regional grid after the filter measurement update of the t+1th batch, The orbit parameters or clock error parameters of all satellites in the current regional grid after the filter time of the t+1th batch is updated. is the parameter covariance of all satellites in the current regional grid after the filter time update of the t+1th batch, H is the design matrix, Y is the measurement residual, R is the measurement error matrix, It is the parameter covariance of all satellites in the current regional grid after the filter measurement update of the t+1th batch.

[0057] Step S7: Send the first update result to each satellite in the current regional grid through different intersatellite links, and control each satellite to use the corresponding orbit and clock error dynamics model, and use the numerical integration method to perform distributed Kalman filter time update to obtain the second update result, and send the second update result to the node satellite in the current regional grid; the second update result includes: the orbit parameters, clock error parameters and parameter covariance of the corresponding satellite in the current regional grid after the filter time is updated.

[0058] In this embodiment, after the node satellite of each regional grid completes the partitioned centralized Kalman filter measurement update processing, the orbital parameters, clock error and parameter covariance of each satellite after measurement improvement are sent to the corresponding satellite in the current regional grid respectively. Each satellite in the current regional grid uses its orbital dynamics model and satellite clock error dynamic model, and adopts a numerical method to calculate the orbital parameters, clock error parameters and parameter covariance of the next batch forecast of the satellite, and sends the forecast results to the node satellite in the current regional grid, completing the update processing of the orbital parameters and clock error parameters of the satellite in the current regional grid.

[0059] The calculation formula for the second update result is:

[0060]

[0061] In the formula, is the orbit parameter or clock error parameter of satellite i in the current regional grid after the filter time of the t+1th batch is updated, is the satellite state transfer matrix of satellite i from the tth batch to the t+1th batch in the current regional grid, is the orbit parameter or clock error parameter of satellite i in the current regional grid after the filter measurement update of the tth batch, is the parameter covariance of satellite i in the current regional grid after the filter time update of the t+1th batch, is the parameter covariance of satellite i in the current regional grid after the filter measurement update of the tth batch, W i is the dynamic noise matrix of satellite i in the current regional grid.

[0062] Step S8: Control the node satellites in the current regional grid to send all received second update results to the node satellites in the adjacent regional grids to complete the satellite orbit determination and time synchronization of a single batch.

[0063] In this embodiment, after the node satellite in each regional grid collects the predicted values ​​of the orbital parameters and clock error parameters of all satellites in the current regional grid, it uses the inter-satellite link to send the results of Kalman filter measurement update and time update processing in the current regional grid to the node satellite in the adjacent regional grid, completing the partitioned centralized precise orbit determination and time synchronization processing of a single batch of the entire network, and then proceeding to the next batch of measurements.

[0064] Step S9: After all satellites in the Giant Star constellation have completed orbit determination and time synchronization for a single batch, steps S5 to S8 are repeated for each regional grid, and multiple batches of satellite orbit determination and time synchronization are continuously performed.

[0065] In this embodiment, it is necessary to complete the precise orbit determination and time synchronization data processing of all satellites in chronological order.

[0066] In summary, this embodiment proposes a new method for gridding Giant Star satellites, using a partitioned centralized processing method to perform Kalman filter measurement update, and using a single-satellite distributed processing method to perform time update. This solves the problem that GNSS is susceptible to interference or deception, and that only inter-satellite measurements are supported for precise orbit determination and time synchronization of Giant Star satellites, and reduces the impact of insufficient number of inter-satellite links and measurement topology configuration of some satellites on accuracy and stability.

[0067] In addition, this embodiment can be applied to autonomous orbit determination and time synchronization processing of Giant Star satellites with only intersatellite measurement support, solving the problem of precise orbit and clock error determination under the condition of insufficient intersatellite links of some satellites. When the satellite has GNSS observation support conditions, the intersatellite link information provided by this embodiment can also be combined with GNSS information, which is conducive to further improving the accuracy of orbit and clock error determination.

[0068] Example 2

[0069] This embodiment provides a computer device, which may be a server or a terminal. Its internal structure diagram may be as follows: Figure 3 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for centralized orbit determination and time synchronization of a giant star constellation partition supported by intersatellite measurement is implemented.

[0070] Those skilled in the art will understand that Figure 3 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0071] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0072] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0073] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0074] All actions to obtain signals, information or data in this application are carried out in compliance with the relevant data protection laws and policies of the country where they are located, and with the authorization given by the owner of the corresponding device.

[0075] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0076] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for centralized orbit determination and time synchronization of giant star constellations supported by intersatellite measurement, characterized in that: The method for centralized orbit determination and time synchronization of giant star constellation partitions supported by intersatellite measurement includes: According to the pre-designed intersatellite link building strategy, intersatellite links for mutual transmission and reception between different satellites in the giant star constellation are constructed; each satellite in the giant star constellation is equipped with laser or microwave intersatellite measurement and communication equipment; Control each satellite in the giant star constellation to periodically acquire two-way inter-satellite ranging data with the corresponding satellite for link building, as well as orbital parameters, clock error parameters and parameter covariance of the corresponding satellite for link building; Controlling each satellite in the giant star constellation to perform system error correction on the received two-way inter-satellite ranging data, and performing measurement time normalization and signal propagation path correction on the two-way inter-satellite ranging data after the system error correction, so as to obtain instantaneous inter-satellite observation amount; Based on the intersatellite link establishment strategy, a specific topological configuration is used to spatially partition all satellites in the giant star constellation to obtain multiple regional grids, and node satellites in each of the regional grids are determined; multiple intersatellite links exist between different satellites in the same regional grid; and multiple intersatellite links also exist between adjacent regional grids; For each of the regional grids, the following steps are performed synchronously: Send all observation data to the node satellites in the current regional grid; the all observation data include: instantaneous inter-satellite observation quantities between all satellites in the current regional grid, instantaneous inter-satellite observation quantities between each satellite in the current regional grid and the corresponding satellites in the built-in chain of adjacent regional grids, and orbit parameters, clock error parameters and parameter covariance of satellites in the built-in chain of adjacent regional grids corresponding to each satellite in the current regional grid; the current regional grid is any one of the multiple regional grids; Control the node satellites in the current regional grid to perform centralized Kalman filter measurement update using all the observation data to obtain a first update result; the first update result includes: orbit parameters, clock error parameters and parameter covariance of all satellites in the current regional grid after the filter measurement update; The first update result is sent to each satellite in the current regional grid through different intersatellite links, and each satellite is controlled to use the corresponding orbit and clock error dynamics model and adopt a numerical integration method to perform distributed Kalman filter time update to obtain a second update result, and the second update result is sent to the node satellite in the current regional grid; the second update result includes: the orbit parameters, clock error parameters and parameter covariance of the corresponding satellite in the current regional grid after the filter time is updated; Control the node satellites in the current regional grid to send all received second update results to the node satellites in the adjacent regional grids, so as to complete the satellite orbit determination and time synchronization of a single batch; After all satellites in the giant star constellation have completed orbit determination and time synchronization for a single batch, the above steps are repeated for each regional grid to continuously perform orbit determination and time synchronization for multiple batches of satellites.

2. The method for centralized orbit determination and time synchronization of giant star constellations supported by intersatellite measurements according to claim 1, characterized in that: The system error correction includes at least: equipment receiving and transmitting delay error correction, relativity error correction, antenna phase center error correction, and tropospheric and ionospheric signal propagation delay error correction.

3. The method for centralized orbit determination and time synchronization of giant star constellations supported by intersatellite measurements according to claim 1, characterized in that: The specific topological configuration is a cellular space topological configuration.

4. The method for centralized orbit determination and time synchronization of giant star constellations supported by intersatellite measurements according to claim 1, characterized in that: There are one or two node satellites in each of the regional grids; when there are two node satellites in each of the regional grids, any one of the two node satellites is selected to be used as a backup satellite.

5. The method for centralized orbit determination and time synchronization of giant star constellations supported by intersatellite measurements according to claim 1, characterized in that: Determining the node satellites in each of the regional grids specifically includes: For any regional grid, determine the onboard data processing and storage capacity of each satellite in the any regional grid, count the number of inter-satellite links between the satellites in the any regional grid, and the number of inter-satellite links between each satellite in the any regional grid and the satellites in the corresponding adjacent regional grid; One or two satellites are selected as node satellites from all the satellites in any regional grid according to the onboard data processing and storage capacity of each satellite in any regional grid and the corresponding number of inter-satellite links.

6. The method for centralized orbit determination and time synchronization of giant star constellations supported by intersatellite measurements according to claim 1, characterized in that: The instantaneous intersatellite observations include: instantaneous intersatellite ranging observations and instantaneous intersatellite time synchronization observations; the instantaneous intersatellite ranging observations are used to determine the instantaneous intersatellite ranging residual and the two-way intersatellite distance; the instantaneous intersatellite time synchronization observations are used to determine the instantaneous intersatellite time residual; the linearized observation equation of the intersatellite link between different satellites in the same regional grid is: Dr. ij =H i X i -H j X j +e ij ; In the formula, Δρ ij is the instantaneous inter-satellite ranging residual or instantaneous inter-satellite time residual between satellite i and satellite j in the current regional grid, X i is the orbit parameter or clock error parameter of satellite i in the current regional grid, X j is the orbit parameter or clock error parameter of satellite j in the current regional grid, H i For X i The corresponding design matrix, H j For X j The corresponding design matrix, ε ij is the random noise of the instantaneous inter-satellite ranging observation or the random noise of the instantaneous inter-satellite time synchronization observation between satellite i and satellite j in the current regional grid, are the coordinates x of satellite i in the current regional grid respectively. i The three components of are the coordinates x of satellite j in the current regional grid. j The three components of ij is the two-way inter-satellite distance between satellite i in the current regional grid and satellite j in the current regional grid.

7. The method for centralized orbit determination and time synchronization of giant star constellations supported by intersatellite measurements according to claim 6, characterized in that: The linearized observation equation of the intersatellite link between adjacent regional grids is: Dr. i ′ k =Dr. ik +H k ′X k ′=H i X i +e i ′ k ; In the formula, Δρ i ' k is the equivalent inter-satellite ranging residual or equivalent inter-satellite time residual between satellite i in the current regional grid and satellite k in the adjacent regional grid, Δρ ik is the instantaneous inter-satellite ranging residual or instantaneous inter-satellite time residual between satellite i in the current regional grid and satellite k in the adjacent regional grid, X k ′ is the orbit parameter or clock error parameter of satellite k in the adjacent regional grid, H k ′ is X k ′ corresponds to the design matrix, ε i ' k is the random noise of the equivalent inter-satellite ranging observation or the equivalent inter-satellite time synchronization observation between satellite i in the current regional grid and satellite j in the adjacent regional grid, ε ik is the random noise of the instantaneous inter-satellite ranging observation or the random noise of the instantaneous inter-satellite time synchronization observation between satellite i in the current regional grid and satellite j in the adjacent regional grid, is the parameter covariance of satellite k in the adjacent regional grid.

8. The method for centralized orbit determination and time synchronization of giant star constellations supported by intersatellite measurements according to claim 1, characterized in that: The calculation formula of the first update result is: In the formula, The orbit parameters or clock error parameters of all satellites in the current regional grid after the filter measurement update of the t+1th batch, The orbit parameters or clock error parameters of all satellites in the current regional grid after the filter time of the t+1th batch is updated. is the parameter covariance of all satellites in the current regional grid after the filter time update of the t+1th batch, H is the design matrix, Y is the measurement residual, R is the measurement error matrix, It is the parameter covariance of all satellites in the current regional grid after the filter measurement update of the t+1th batch.

9. The method for centralized orbit determination and time synchronization of giant star constellations supported by intersatellite measurements according to claim 1, characterized in that: The calculation formula of the second update result is: In the formula, is the orbit parameter or clock error parameter of satellite i in the current regional grid after the filter time of the t+1th batch is updated, is the satellite state transfer matrix of satellite i from the tth batch to the t+1th batch in the current regional grid, is the orbit parameter or clock error parameter of satellite i in the current regional grid after the filter measurement update of the tth batch, is the parameter covariance of satellite i in the current regional grid after the filter time update of the t+1th batch, is the parameter covariance of satellite i in the current regional grid after the filter measurement update of the tth batch, W i is the dynamic noise matrix of satellite i in the current regional grid.

10. A computer system comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for centralized orbit determination and time synchronization of giant star constellations supported by intersatellite measurements as described in any one of claims 1 to 9.

Images