All-time positioning guarantee method and system for static meteorological satellite lightning imager

Abstract

The invention provides an all-time positioning guarantee method and system for a static meteorological satellite lightning imager, and aims to construct a full-link error model of reference deformation of the lightning imager in order to solve the problem that the current lightning imager lacks a geometric calibration point at night and the positioning precision is difficult to guarantee. A high-precision image positioning guarantee method combining landmark observation and an on-satellite thermal deformation measurement system is designed, the image positioning precision in the daytime is guaranteed through landmark observation, and the image positioning precision at night is guaranteed through the on-satellite thermal deformation measurement system. According to the invention, the all-time image positioning precision of the lightning imager can be effectively ensured.

Description

Technical Field

[0001] The present invention belongs to the general technical field of space vehicles, and specifically, relates to a method and system for ensuring all-weather positioning of a lightning imager on a geostationary meteorological satellite. Background Art

[0002] The lightning imager is one of the main payloads of a geostationary meteorological satellite, and can realize real-time monitoring of lightning events in the covered area throughout the day. Image positioning is an important index of the lightning imager, which is used to ensure the accurate position information of lightning events. The main factor affecting the positioning accuracy of the lightning imager is on-orbit thermal deformation. Due to the complex thermal environment of a geostationary orbit satellite, the temperature outside the remote sensing payload varies significantly within one orbital period, resulting in complex long-period thermal deformation of the imaging reference of the lightning imager relative to the satellite attitude measurement reference. The conventional method for identifying on-orbit long-period thermal deformation is geometric calibration based on landmarks and stars. However, the lightning imager does not have the ability of infrared imaging and cannot perform geometric calibration at night. Therefore, how to solve the thermal deformation identification at night is the key problem for ensuring all-weather high-precision image positioning.

[0003] After literature retrieval, Cheng Kai, Tong Xiaochong, Liu Shanjun, etc. mentioned in the published paper "On-orbit Geometric Calibration of the Lightning Imager on Fengyun-4A Satellite with Double-Lens Edge-Matching Processing" (Journal of Geomatics Science and Technology, 2021) that the lightning imager on Fengyun-4A satellite uses a double-lens design, and there are lens separation errors and internal and external orientation errors during the on-orbit imaging process. High-precision on-orbit geometric calibration is the key to ensuring the data application of the lightning imager. Using the control data of on-orbit landmark matching and adopting the edge-matching processing technology to solve the internal and external calibration parameters and the edge parameters together can correct the inconsistency problem in the pointing between the two lenses and improve the positioning accuracy. This article describes the geometric positioning method based on landmark observation and does not involve the solution for high-precision positioning at night.

[0004] Zhang Xiaohuang proposed in the master's degree thesis "Three-Dimensional Positioning of Low-Frequency Magnetic Field Lightning Radiation Sources and Preliminary Evaluation of the Detection Performance of the FY-4A Lightning Imager" (Journal of Geomatics Science and Technology, 2019) that based on the ground-based low-frequency magnetic field lightning detection system combined with the ground-based synchronous networking lightning observation data, the detection performance and geometric positioning accuracy of the lightning imager for lightning can be evaluated. This paper mainly introduces the evaluation method of positioning accuracy and does not involve the method for ensuring high-precision positioning on the satellite.

[0005] Liang Hua, Bao Shulong, Chen Qiang, etc. introduced the design and implementation of the first space optical remote sensing instrument for detecting lightning in China, the lightning imager carried by the FY-4 satellite, in the published paper "Design and Implementation of the FY-4 Satellite Lightning Imager" (Aerospace Shanghai, 2017). They elaborated on the key technological breakthroughs in the overall subsystem of the lightning imager, the application of ultra-narrowband filters, high-frame-rate CCD devices, real-time event processors, laboratory calibration and verification of the lightning imager, etc. However, the paper did not cover the relevant content of ensuring all-weather high-precision image positioning.

[0006] Zou Yaoren, Wang Yun, Wang Shuyi, etc. proposed an evaluation of the detection efficiency of the FY-4A lightning imager (LMI) in the Yellow Sea and Bohai Sea regions based on the data of the ground-based three-dimensional lightning detection network in Dalian and Qingdao areas in the published paper "Evaluation of the Detection Effect of the FY-4A Lightning Imager (LMI) in the Yellow Sea and Bohai Sea Regions" (Arid Meteorology, 2021). After comparison, the spatial positions of the lightning activities detected by the ground-based three-dimensional lightning detection network and FY-4A were relatively consistent, both basically in the core area of strong convection. However, the paper did not cover the relevant content of ensuring all-weather high-precision image positioning.

[0007] Cao Dongjie proposed in the published paper "Research Progress on the Monitoring Principle and Product Algorithm of the Geostationary Satellite Lightning Imager of FY-4" (Advances in Meteorological Science and Technology, 2016) that the geostationary satellite lightning imager realizes lightning positioning through optical imaging detection, can continuously monitor lightning activities for a long time, and provides an observational basis for severe convective weather warning and regional lightning activity characteristic research in the Chinese region. This paper introduced the working principle and product algorithm of the FY-4 geostationary satellite lightning imager in combination with the research status of foreign geostationary satellite lightning imagers. However, the paper did not cover the relevant content of ensuring all-weather high-precision image positioning.

[0008] After investigation and analysis, there is no public report on similar technologies for the all-weather positioning guarantee method of the geostationary meteorological satellite lightning imager proposed by the present invention. Summary of the Invention

[0009] Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide an all-weather positioning guarantee method and system for a geostationary meteorological satellite lightning imager.

[0010] An all-weather positioning guarantee system for a geostationary meteorological satellite lightning imager according to the present invention includes: a lightning imager, a star sensor, a thermal deformation measurement system, and a reflecting prism;

[0011] The thermal deformation measurement system is installed on the star sensor reference, and the reflecting prism is installed on the lightning imager reference;

[0012] The thermal deformation measurement system emits a beam of light, which is reflected back into the system by a reflecting prism to measure the thermal deformation of the installation reference of the lightning imager relative to the installation reference of the star sensor.

[0013] Preferably, the lightning imager has the function of imaging the ground through the visible light channel, and identifies the thermal deformation change of the imaging reference of the lightning imager relative to the satellite attitude reference by observing landmarks, ensuring image positioning during the day;

[0014] The star sensor is the absolute reference for attitude measurement of the satellite platform, and the measurement data is the input for calculating the optical axis pointing of the lightning imager.

[0015] Preferably, it includes:

[0016] Module M1: Establish a full-link error model for the reference deformation of the lightning imager;

[0017] Module M2: Based on the full-link error model, perform daytime image positioning of the lightning imager;

[0018] Module M3: Based on the full-link error model, perform nighttime image positioning of the lightning imager.

[0019] Preferably, in the module M1, the expression of the full-link error model for the reference deformation of the lightning imager is as follows:

[0020]

[0021] In the above formula, r0 is the projection of the payload line of sight in the payload imaging coordinate system, r S is the projection of the payload line of sight in the satellite body coordinate system, C C_S is the installation matrix of the lightning imager relative to the star sensor;

[0022] ψ H 、λ H 、θ H are the thermal deformation parameters of the reference prism of the lightning imager relative to the star sensor bracket, and are monitored in real time by the thermal deformation measurement system when landmark observation cannot be performed at night;

[0023] ψ R 、λ R 、θ R are the equivalent parameters of the internal thermal deformation of the lightning imager and the thermal deformation of the star sensor bracket, and are jointly identified by combining the landmark observation data during the day.

[0024] Preferably, in the module M2, landmarks are observed through the visible light channel during the day, and thermal deformation is identified using the landmark data. The expression of the landmark observation is as follows:

[0025] r S =A C_S ·CC_S ·r0

[0026] In the above formula, r0 is the projection of the line of sight of the load observation landmark in the load imaging coordinate system, which is calculated based on the extraction result of the landmark image and combined with the geometric imaging model of the lightning imager;

[0027] C C_S is the installation matrix of the lightning imager relative to the star sensor;

[0028] r S is the projection of the line of sight of the load observation landmark in the satellite body coordinate system, which is calculated based on the geographical longitude and latitude data of the landmark and combined with the real-time attitude and orbit information of the satellite;

[0029] A C_S is the thermal deformation matrix of the imaging reference of the lightning imager relative to the measurement reference of the star sensor, which is identified through the landmark observation of the lightning imager.

[0030] In the landmark observation process, using the measurement results of r0, C C_S and r S , through two landmark observations, the thermal deformation matrix A C_S is identified; when locating the lightning event, the identified thermal deformation matrix A C_S is brought into the positioning process to ensure the image positioning accuracy during the day.

[0031] Preferably, in the module M3, according to the expression:

[0032]

[0033] During the daytime landmark observation, combining the landmark observation data and the measurement results of the thermal deformation measurement system, the equivalent thermal deformation parameters ψ R , λ R , θ R are identified;

[0034] The equivalent thermal deformation parameters ψ R , λ R , θ R are ensured to be stable through on-orbit temperature control and integrated layout; during the nighttime lightning event positioning, combining the identified equivalent thermal deformation parameters (ψ R , λ R , θ R ) and the measurement data of the thermal deformation measurement system (ψ H , λ H , θ H ), the thermal deformation matrix A C_S at night is calculated in real time, and the lightning event is located.

[0035] A method for ensuring all-day positioning of a lightning imager on a geostationary meteorological satellite provided by the present invention includes:

[0036] Step S1: Establish a full-link error model for the reference deformation of the lightning imager;

[0037] Step S2: Based on the full-link error model, perform daytime image positioning of the lightning imager;

[0038] Step S3: Based on the full-link error model, perform nighttime image positioning of the lightning imager.

[0039] Preferably, in the step S1, the expression of the full-link error model for the reference deformation of the lightning imager is as follows:

[0040]

[0041] In the above formula, r0 is the projection of the payload line of sight in the payload imaging coordinate system, and r S is the projection of the payload line of sight in the satellite body coordinate system, and C C_S is the installation matrix of the lightning imager relative to the star sensor;

[0042] ψ H 、λ H 、θ H are the thermal deformation parameters of the reference prism of the lightning imager relative to the star sensor bracket, and are monitored in real time by a thermal deformation measurement system when landmark observations cannot be performed at night;

[0043] ψ R 、λ R 、θ R are the equivalent parameters of the internal thermal deformation of the lightning imager and the thermal deformation of the star sensor bracket, and are jointly identified by combining the landmark observation data during the day.

[0044] Preferably, in the step S2, landmarks are observed in the daytime visible light channel, and thermal deformation identification is performed using landmark data. The expression of the landmark observation is as follows:

[0045] r S =A C_S ·C C_S ·r0

[0046] In the above formula, r0 is the projection of the line of sight of the payload observing the landmark in the payload imaging coordinate system, and is calculated by combining the extraction result of the landmark image and the geometric imaging model of the lightning imager;

[0047] C C_S is the installation matrix of the lightning imager relative to the star sensor;

[0048] r SIt is the projection of the line of sight to the load observation landmark in the satellite body coordinate system, which is calculated based on the geographical longitude and latitude data of the landmark, combined with the real-time attitude and orbit information of the satellite;

[0049] A C_S It is the thermal deformation matrix of the imaging reference of the lightning imager relative to the measurement reference of the star sensor, which is identified through the landmark observation of the lightning imager.

[0050] In the landmark observation process, using the measurement results of r0, C C_S and r S Through two landmark observations, the thermal deformation matrix A C_S is identified; during lightning event positioning, the identified thermal deformation matrix A C_S is brought into the positioning process to ensure the image positioning accuracy during the day.

[0051] Preferably, in the step S3, according to the expression:

[0052]

[0053] During daytime landmark observation, combining landmark observation data and the measurement results of the thermal deformation measurement system, the equivalent thermal deformation parameters ψ R 、λ R 、θ R are identified;

[0054] The equivalent thermal deformation parameters ψ R 、λ R 、θ R are ensured to be stable through on-board temperature control and integrated layout; during nighttime lightning event positioning, combining the identified equivalent thermal deformation parameters (ψ R 、λ R 、θ R ) and the measurement data of the thermal deformation measurement system (ψ H 、λ H 、θ H ), the thermal deformation matrix A C_S at night is calculated in real time, and lightning event positioning is carried out.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] 1. The present invention constructs a full-link error model for the reference deformation of the lightning imager, designs a high-precision image positioning guarantee method combining landmark observation and on-board thermal deformation measurement system, ensures the image positioning accuracy during the day through landmark observation, and ensures the image positioning accuracy at night through the on-board thermal deformation measurement system.

[0057] 2. The present invention solves the problem that the current lightning imager lacks geometric calibration points at night and it is difficult to ensure the positioning accuracy.

[0058] 3. The present invention can effectively ensure the all-weather image positioning accuracy of the lightning imager. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Other features, objects, and advantages of the present invention will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings:

[0060] Figure 1 It is a schematic diagram of the composition structure of the on-satellite all-weather positioning guarantee system.

[0061] Figure 2 It is a schematic diagram of the steps of the on-satellite all-weather positioning processing flow.

[0062] As shown in the figure:

[0063] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0064] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several changes and improvements can still be made. These all belong to the protection scope of the present invention.

[0065] As Figure 1 , Figure 2 shown, according to an all-weather positioning guarantee method for a geostationary meteorological satellite lightning imager provided by the present invention, an all-weather positioning guarantee system for a geostationary meteorological satellite lightning imager is adopted.

[0066] The present invention constructs a full-link error model for the lightning imager reference deformation, establishes the transfer relationship between the "imaging reference of the lightning imager, prism reference, thermal deformation measurement reference, and star sensor measurement reference", and forms a thermal deformation identification model through model simplification. When the satellite is in orbit, the image positioning accuracy during the day is ensured through landmark observations, and the image positioning accuracy at night is ensured through the on-satellite thermal deformation measurement system. During the process of identifying the thermal deformation of the lightning imager, the landmark observation data during the day can be combined with the thermal deformation measurement data to identify the thermal deformation of the star sensor and the lightning imager itself.

[0067] The all-weather positioning guarantee system for the geostationary meteorological satellite lightning imager includes:

[0068] (1) All-weather positioning guarantee system

[0069] The on-satellite all-weather positioning guarantee involves the lightning imager, star sensor, thermal deformation measurement system, and reflection prism. The specific system composition and on-satellite layout are shown in Figure 1 as shown.

[0070] Among them, the lightning imager, as a payload, has the function of imaging the ground through the visible light channel, and can identify the thermal deformation change of the imaging reference of the lightning imager relative to the satellite attitude reference through landmark observation, ensuring high-precision image positioning during the day.

[0071] The star sensor is the absolute reference for attitude measurement of the satellite platform. The measurement data is an important input for calculating the optical axis pointing of the lightning imager, and its measurement accuracy also directly affects the final image positioning accuracy.

[0072] The thermal deformation measurement system is used in combination with the reflecting prism. As Figure 1 shown, the thermal deformation measurement system is installed on the star sensor reference, and the reflecting prism is installed on the lightning imager reference. The thermal deformation measurement system emits a beam of light, which is reflected back into the thermal deformation measurement system through the reflecting prism, and can measure the thermal deformation of the lightning imager installation reference relative to the star sensor installation reference.

[0073] (2) Full-link error modeling of the reference deformation of the lightning imager

[0074] The attitude reference of the satellite is the star sensor. In the image positioning process, it is necessary to rely on the measurement data of the star sensor to determine the optical axis pointing of the lightning imager. However, since the lightning imager and the star sensor are installed at different positions on the satellite and are affected by temperature alternation in orbit, it will cause deformation of the imaging reference of the lightning imager relative to the measurement reference of the star sensor, seriously affecting the image positioning accuracy.

[0075] To solve the reference deformation of the lightning imager, first establish a full-link error model, and the expression is as follows:

[0076] r S = A H_T ·A L_H ·A C_L ·C C_S ·r0

[0077] In the above formula, r0 is the projection of the payload line of sight in the payload imaging coordinate system, r S is the projection of the payload line of sight in the satellite body coordinate system, C C_S is the installation matrix of the lightning imager relative to the star sensor, which can be obtained through precise ground measurement. The satellite body coordinate system is the star sensor measurement coordinate system.

[0078] A C_L is the thermal deformation matrix of the lightning imager imaging reference relative to the reflecting prism, and the expression is as follows:

[0079]

[0080] In the above formula, ψ L 、λL and θ L is the imaging reference thermal deformation angle of the lightning imager.

[0081] ψ represents the thermal deformation angle in the Z-axis direction.

[0082] λ represents the thermal deformation angle in the Y-axis direction.

[0083] θ represents the thermal deformation angle in the X-axis direction.

[0084] The X-axis direction, Y-axis direction, and Z-axis direction are perpendicular to each other. The X-axis direction and Y-axis direction are parallel to the X-axis and Y-axis directions of the acquired image respectively, and the Z-axis direction is the optical axis direction.

[0085] A H T is the thermal deformation matrix of the thermal deformation measurement system relative to the star sensor, and the expression is as follows:

[0086]

[0087] In the above formula, ψ H and λ H and θ H are the thermal deformation angles of the reflecting prism relative to the thermal deformation measurement system.

[0088] A L_H is the thermal deformation matrix of the reflecting prism relative to the thermal deformation measurement system, and the expression is as follows:

[0089]

[0090] In the above formula, ψ T and λ T and θ T are the thermal deformation angles of the thermal deformation measurement system relative to the star sensor.

[0091] Considering that the thermal deformation parameters of the satellite are small angles, after small angle combination and simplification, the new expression is as follows:

[0092]

[0093] In the above formula, ψ H and λ H and θ H are the thermal deformation parameters of the reference prism of the lightning imager relative to the star sensor bracket, which are the main components of the thermal deformation of the lightning imager. When landmark observation cannot be carried out at night, real-time monitoring can be carried out through the thermal deformation measurement system.

[0094] ψ R and λ R and θ RIt is the equivalent parameter of the internal thermal deformation of the lightning imager and the thermal deformation of the star sensor support, which is a small amount of the thermal deformation of the lightning imager. Its stability can be ensured through precise on-orbit temperature control and integrated layout, and it can be jointly identified by combining the landmark observation data during the day.

[0095] (3) Lightning imager daytime image positioning process

[0096] According to the working principle of the lightning imager, landmarks can be observed in the visible light channel during the day, and the thermal deformation can be directly identified using the landmark data to ensure the positioning accuracy. The expression for landmark observation is as follows:

[0097] r S = A C_S ·C C_S ·r0

[0098] In the above formula, r0 is the projection of the line of sight of the payload observing the landmark in the payload imaging coordinate system, which can be calculated based on the extraction result of the landmark image and combined with the geometric imaging model of the lightning imager.

[0099] C C_S is the installation matrix of the lightning imager relative to the star sensor, which is a constant value and can be obtained through precise ground measurement.

[0100] r S is the projection of the line of sight of the payload observing the landmark in the satellite body coordinate system, which can be calculated based on the geographical longitude and latitude data of the landmark and combined with the real-time attitude and orbit information of the satellite.

[0101] A C_S is the thermal deformation matrix of the imaging reference of the lightning imager relative to the measurement reference of the star sensor, which is a key parameter affecting image positioning and is identified through the landmark observation of the lightning imager.

[0102] According to the above analysis, in the landmark observation process, using the measurement results of r0, C C_S and r S , through two landmark observations, the thermal deformation matrix A C_S can be effectively identified. When positioning lightning events, substituting the identified thermal deformation matrix A C_S into the positioning process can ensure the daytime image positioning accuracy.

[0103] (4) Lightning imager nighttime image positioning process

[0104] Since the lightning imager only has the visible spectral band and does not have the ability to observe at night, thermal deformation observation cannot be based on landmarks at night. The present invention proposes a thermal deformation identification method based on on-orbit thermal deformation measurement. According to the above analysis, first expand the thermal deformation matrix A C_S , and the expression is:

[0105]

[0106] In the above formula, ψ H , λ H , θ H are the thermal deformation parameters of the reference prism of the lightning imager relative to the star sensor bracket, which are the main components of the thermal deformation of the lightning imager and can be monitored in real time through the thermal deformation measurement system.

[0107] ψ R , λ R , θ R are the equivalent parameters of the internal thermal deformation of the lightning imager and the thermal deformation of the star sensor bracket, which cannot be directly measured by the thermal deformation measurement system and need to be identified.

[0108] Through matrix transformation, the above expression can be rewritten as:

[0109]

[0110] According to the above expression, during daytime landmark observations, by combining the landmark observation data and the measurement results of the thermal deformation measurement system, the equivalent thermal deformation parameters ψ R , λ R , θ R can be identified.

[0111] This equivalent parameter is a small amount of the thermal deformation of the lightning imager, and its stability can be ensured through on-board precise temperature control and integrated layout. During nighttime lightning event positioning, the identified equivalent thermal deformation parameters (ψ R , λ R , θ R ) and the measurement data of the thermal deformation measurement system (ψ H , λ H , θ H ) can be combined to calculate the thermal deformation matrix A C_S in real time at night and perform high-precision lightning event positioning.

[0112] In the description of this application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0113] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A full-time positioning guarantee system for a lightning imager of a geostationary meteorological satellite, characterized in that, Including: Lightning imager, star sensor, thermal deformation measurement system, reflection prism; The thermal deformation measurement system is installed on the star sensor reference, and the reflection prism is installed on the lightning imager reference; The thermal deformation measurement system emits a beam of light, which is reflected back into the thermal deformation measurement system through the reflection prism to measure the thermal deformation of the installation reference of the lightning imager relative to the installation reference of the star sensor.

2. The all-weather positioning guarantee system for the geostationary meteorological satellite lightning imager according to claim 1, wherein The lightning imager has the function of imaging the ground through the visible light channel, and identifies the thermal deformation change of the imaging reference of the lightning imager relative to the satellite attitude reference by observing the ground landmarks, ensuring image positioning during the day; The star sensor is the absolute reference for attitude measurement of the satellite platform, and the measurement data is the input for calculating the optical axis pointing of the lightning imager.

3. The all-weather positioning assurance system method for the geostationary meteorological satellite lightning imager according to claim 1, characterized in that, Including: Module M1: Establish a full-link error model for the reference deformation of the lightning imager; Module M2: Perform daytime image positioning of the lightning imager based on the full-link error model; Module M3: Perform nighttime image positioning of the lightning imager based on the full-link error model.

4. The all-weather positioning assurance system for the geostationary meteorological satellite lightning imager according to claim 3, characterized in that, In the module M1, the expression of the full-link error model for the reference deformation of the lightning imager is as follows: In the above formula, r0 is the projection of the load line of sight in the load imaging coordinate system, and r S is the projection of the load line of sight in the satellite body coordinate system, and C C_S is the installation matrix of the lightning imager relative to the star sensor; ψ H , λ H , θ H are the thermal deformation parameters of the reference prism of the lightning imager relative to the star sensor bracket, and are monitored in real time by the thermal deformation measurement system when landmark observations cannot be carried out at night; ψ R , λ R , θ R are the equivalent parameters of the internal thermal deformation of the lightning imager and the thermal deformation of the star sensor bracket, and are jointly identified by combining the landmark observation data during the day.

5. The all-weather positioning assurance system for the geostationary meteorological satellite lightning imager according to claim 3, characterized in that In the module M2, observe the ground landmarks in the daytime visible light channel, and use the landmark data to identify the thermal deformation. The expression of the landmark observation is as follows: r S = A C_S · C C_S · r0 In the above formula, r0 is the projection of the line of sight of the payload observing the ground landmark in the payload imaging coordinate system, which is calculated based on the extraction result of the landmark image and combined with the geometric imaging model of the lightning imager; C C_S is the installation matrix of the lightning imager relative to the star sensor; r S It is the projection of the line of sight to the payload observation landmark in the satellite body coordinate system, which is calculated based on the geographical longitude and latitude data of the landmark and combined with the real-time attitude and orbit information of the satellite. A C_S is the thermal deformation matrix of the imaging reference of the lightning imager relative to the measurement reference of the star sensor, which is identified by the landmark observation of the lightning imager. In the landmark observation process, using the measurement results of r0, C C_S and r S through two landmark observations, the thermal deformation matrix A C_S is identified; when locating lightning events, the identified thermal deformation matrix A C_S is brought into the positioning process to ensure the image positioning accuracy during the day.

6. The all-weather positioning assurance system for the geostationary meteorological satellite lightning imager according to claim 3, characterized in that In the module M3, according to the expression: During daytime landmark observations, by combining landmark observation data with the measurement results of the thermal deformation measurement system, the identification of the equivalent thermal deformation parameters ψ R , λ R , θ R is achieved; Equivalent thermal deformation parameters ψ R , λ R , θ R Ensure stability through on-orbit temperature control and integrated layout; during nighttime lightning event localization, combine the identified equivalent thermal deformation parameters (ψ R , λ R , θ R ) and the measurement data of the thermal deformation measurement system (ψ H , λ H , θ H ) to calculate the thermal deformation matrix A C_S in real time at night and perform lightning event localization.

7. A method for ensuring all-day positioning of a lightning imager on a geostationary meteorological satellite, characterized in that, Including: Step S1: Establish a full-link error model for the reference deformation of the lightning imager; Step S2: Perform daytime image positioning of the lightning imager based on the full-link error model; Step S3: Perform nighttime image positioning of the lightning imager based on the full-link error model.

8. The all-weather positioning guarantee method for the geostationary meteorological satellite lightning imager according to claim 7, wherein In the step S1, the expression of the full-link error model for the reference deformation of the lightning imager is as follows: In the above formula, r0 is the projection of the payload line of sight in the payload imaging coordinate system, and r S is the projection of the payload line of sight in the satellite body coordinate system, and C C_S is the installation matrix of the lightning imager relative to the star sensor; ψ H , λ H , θ H are the thermal deformation parameters of the reference prism of the lightning imager relative to the star sensor bracket. When landmark observations cannot be carried out at night, real-time monitoring is carried out through the thermal deformation measurement system; ψ R , λ R , θ R are the equivalent parameters of the internal thermal deformation of the lightning imager and the thermal deformation of the star sensor bracket, and are jointly identified by combining the landmark observation data during the day.

9. The all-weather positioning guarantee method for the geostationary meteorological satellite lightning imager according to claim 7, wherein In the step S2, observe the ground landmarks in the daytime visible light channel, and use the landmark data to identify the thermal deformation. The expression of the landmark observation is as follows: r S = A C_S · C C_S · r0 In the above formula, r0 is the projection of the line of sight of the payload observing the ground landmark in the payload imaging coordinate system, which is calculated based on the extraction result of the landmark image and combined with the geometric imaging model of the lightning imager; C C_S is the installation matrix of the lightning imager relative to the star sensor; r S It is the projection of the line of sight to the payload observation landmark in the satellite body coordinate system, which is calculated based on the geographical longitude and latitude data of the landmark and combined with the real-time attitude and orbit information of the satellite. A C_S It is the thermal deformation matrix of the imaging reference of the lightning imager relative to the measurement reference of the star sensor, which is identified by the landmark observation of the lightning imager. In the landmark observation process, using the measurement results of r0, C C_S and r S through two landmark observations, the thermal deformation matrix A C_S is identified; when locating lightning events, the identified thermal deformation matrix A C_S is brought into the positioning process to ensure the image positioning accuracy during the day.

10. The all-weather positioning assurance method for the geostationary meteorological satellite lightning imager according to claim 7, characterized in that In the step S3, according to the expression: During daytime landmark observations, by combining landmark observation data and the measurement results of the thermal deformation measurement system, the identification of equivalent thermal deformation parameters ψ R , λ R , θ R is achieved. Equivalent thermal deformation parameters ψ R , λ R , θ R Ensure stability through on-orbit temperature control and integrated layout; during nighttime lightning event positioning, combine the identified equivalent thermal deformation parameters (ψ R , λ R , θ R ) and the measurement data of the thermal deformation measurement system (ψ H , λ H , θ H ) to calculate the thermal deformation matrix A C_S in real time during nighttime and perform lightning event positioning.

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