Optical load real-mounted digital twinborn simulation system

Abstract

The invention relates to an optical load real-installation digital twinning simulation system, which belongs to the technical field of digital twinning and comprises a satellite digital virtual body, an external interface module and an optical load full-digital virtual simulation platform, the simulation platform further comprises an ultra-high-line-frequency low-crosstalk comprehensive electronic module, a mechanism control module, an optical camera imaging simulation module and a focal plane data processing module. The system receives telemetry data and real shot images of an entity satellite, and performs instruction solution, mechanism motion simulation and full-link optical imaging simulation in a simulation platform to generate a virtual degraded image; performing online imaging quality comparison on the virtual degraded image and the real shot image through a focal plane data processing module, and identifying and correcting parameters of the digital twin model according to the online imaging quality comparison; and finally, the corrected model parameters are fed back to the entity satellite, so that the satellite images the ground object target again according to the plan. According to the invention, high-precision virtual-real twinning of the satellite camera is realized, so that the image quality of the satellite camera is higher.

Description

Technical Field

[0001] This invention belongs to the field of digital twin technology, specifically relating to an optical payload implementation digital twin simulation system. Background Technology

[0002] Digital twins are virtual models, or twins, created using digital technology to represent real-world objects. Unlike traditional modeling, they allow for bidirectional information exchange between the real object and its twin, enabling real-time data interaction and synchronization. The real object can send data to the twin, and the twin can send feedback back to the real object. Current digital twin technology utilizes spatial modeling, virtual reality, and augmented reality techniques to provide a visually intuitive 3D display of real-world objects and systems. Digital twins are widely used in aerospace, industrial manufacturing, and other fields.

[0003] Space satellite payload imaging is a crucial method for obtaining Earth images from space. Differences in satellite trajectory, attitude, and camera parameters affect the quality of the output images. Simulation verification provides strong support for optimizing satellite payload control algorithms and predicting trajectory and attitude planning, making pre-launch simulation verification essential. While existing satellite modeling systems can establish digital satellite models to some extent, several problems remain. First, the current satellite payload imaging process involves high degrees of freedom in the imaging link and complex object-image mapping relationships, making it difficult to establish accurate physical models. Second, existing satellite payload simulation systems may not be able to achieve real-time synchronization with the actual satellite attitude and orbit, resulting in time delays between the model output and the actual situation, and significant discrepancies between the obtained images and reality. Summary of the Invention

[0004] To address the issues of existing simulation systems' inability to achieve real-time synchronization between ground feature systems and digital models, as well as the time delay and image parameter differences between physical satellite cameras and digital optical camera models, this invention provides an optical payload physical digital twin simulation system.

[0005] The technical solution adopted in this invention is as follows:

[0006] A digital twin simulation system for optical payload implementation includes:

[0007] The satellite digital virtual entity is connected to the optical payload full digital virtual simulation platform and is used to initialize the optical payload full digital virtual simulation platform. The initialization data includes the onboard interaction status, ground object environmental parameters, camera parameters and imaging modes.

[0008] An external interface module connects to the fully digital virtual simulation platform for optical payloads, used for image quality analysis and displaying simulation results;

[0009] A fully digital virtual simulation platform for optical payloads, including:

[0010] The ultra-high line frequency low crosstalk integrated electronic module is used to receive and decompose instructions from the ground inspection system, calculate the satellite attitude and orbit dynamics model, the complex imaging link irregular image shift compensation model and the spaceborne cooperative imaging control model, and transmit the generated simulation platform data back to the ground inspection system.

[0011] The mechanism control module, connected to the ultra-high line frequency low crosstalk integrated electronic module, is used to receive the desired motion attitude information of the actuator decomposed from the spaceborne collaborative imaging control model, and to verify and plan the focusing and biasing flow composite mechanism.

[0012] The optical camera imaging simulation module is connected to the ultra-high line frequency low crosstalk integrated electronic module. It is used to receive satellite camera parameters decomposed from the satellite attitude and orbit dynamics model and ground object environmental parameters decomposed from the complex imaging link irregular image shift compensation model. It performs full-link imaging simulation by constructing a geometric link model and a radiation response model to generate virtual degraded images.

[0013] The focal plane data processing module is connected to both the mechanism control module and the optical camera imaging simulation module. It receives the execution parameters of the imaging mission satellite platform and payload mechanism during the simulation process, performs real-time comparison of the imaging quality between the virtual degraded image and the real image captured by the on-orbit camera, and performs digital twin model correction based on the comparison results. The corrected mechanism control model parameters and imaging mission working parameters are then uploaded back to the ultra-high frequency low crosstalk integrated electronic module to generate simulation platform data and transmit it back to the ground inspection system. The satellite receives control commands from the ground inspection system and images the ground targets again according to the plan.

[0014] The present invention has the following beneficial effects:

[0015] This invention provides a digital twin simulation system for optical payload installation. The system first collects real data from a physical satellite platform, then transmits the collected telemetry and control commands to a fully digital virtual simulation platform for command decomposition and processing. It compares the differences between the physical and virtual satellite camera and image data, providing feedback on the fidelity of the digital virtual entity, correcting the digital twin model, and finally uploading the corrected mission parameters to update the model's parameters. Compared to model-based satellite modeling methods, this optical payload installation digital twin simulation system can receive data from the physical satellite in real time, update model data, and upload new commands. It gradually improves the simulation accuracy of the digital virtual entity based on the online data of the physical satellite camera, making the resulting digital model closer to the physical satellite camera, thus obtaining a high-precision optical payload installation digital twin model. Attached Figure Description

[0016] Figure 1This is an architecture diagram of an optical payload implementation digital twin simulation system according to an embodiment of the present invention;

[0017] Figure 2 This is a data flow diagram of the operating status of an optical payload-implemented digital twin simulation system as described in an embodiment of the present invention.

[0018] Figure 3 This is a comparison of real-world and simulated images of a target, representing an embodiment of the optical payload digital twin simulation system described in this invention. Detailed Implementation

[0019] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings and preferred embodiments.

[0020] like Figures 1-3 As shown, this embodiment provides an optical payload physical digital twin simulation system, including: a satellite digital virtual body, an external interface module, and an optical payload full digital virtual simulation platform. The satellite digital virtual body and the external interface module are respectively connected to the optical payload full digital virtual simulation platform.

[0021] The satellite digital virtual entity is primarily used for initializing the fully digital virtual simulation platform for the optical payload. Initialization data includes onboard interaction status, ground environment parameters, camera parameters, and imaging modes. Onboard interaction status includes parameters such as initial payload imaging time, imaging duration, target latitude and longitude, satellite attitude and orbit, and camera mounting attitude. Ground environment parameters include solar radiation, atmospheric transmission, and the target. Camera parameters include TDI integral series, imaging spectral bands, spectral response, gain, bias, quantization, and compression ratio. Imaging modes include pushbroom and swingbroom. The initialization of the fully digital virtual simulation platform for the optical payload is performed within the satellite digital virtual entity.

[0022] The external interface module is primarily used for image quality analysis and displaying simulation results. It includes a telemetry and remote control command submodule and an image display and analysis submodule. The external interface module typically uses a CAN (Controller Area Network) bus or an RS422 universal communication interface to communicate with the optical payload's fully digital virtual simulation platform. Specifically, the telemetry and remote control command submodule acquires commands for spatial resolution, dynamic transfer function testing, line frequency testing, and swath width. The image display and analysis submodule performs spatial resolution analysis, dynamic transfer function testing, line frequency testing, and swath width analysis on the images. By acquiring, testing, and analyzing these commands through the external interface module, image quality analysis of satellite camera-transmitted images is performed, and high-resolution wide-swath images are displayed.

[0023] The optical payload fully digital virtual simulation platform includes an ultra-high line frequency low crosstalk integrated electronic module, a mechanism control module, an optical camera imaging simulation module, and a focal plane data processing module.

[0024] The satellite carries a camera and moves in space to reach a designated area. It transmits data through satellite-to-ground communication and establishes a satellite attitude and orbit dynamics solution model in an ultra-high frequency, low crosstalk integrated electronic module. This model includes a satellite attitude and orbit dynamics model, a complex imaging link irregular image shift compensation model, and a satellite-borne collaborative high-stability and high-precision imaging control model, thereby enabling the monitoring of the satellite's attitude and orbit status.

[0025] The satellite acquires environmental information such as atmosphere, clouds, and rain between the ground surface and the satellite camera through an external interface. The ground inspection system packages the telemetry and control commands of the above environmental information and sends them to the ultra-high line frequency and low crosstalk integrated electronic module of the optical camera's all-digital virtual simulation platform. In this module, the commands are decomposed to calculate the satellite attitude and orbit dynamics model, the complex imaging link irregular image shift compensation model, and the onboard collaborative high-stability and high-precision imaging control model, so as to realize the visualization of the virtual ground environment and achieve a preliminary estimate of the environment.

[0026] The desired motion attitude information of the actuators is decomposed from the spaceborne collaborative high-stability and high-precision imaging control model. This information is then sent to the mechanism control module of the simulation platform to verify the accuracy of the focusing and biasing composite mechanism. At this point, the focusing mechanism finds the optimal imaging position, and the biasing composite mechanism changes the focal plane position according to the motion law of the tilting mirror, the satellite's attitude and orbit, and the Earth's rotation, thus imaging the Earth and planning the model.

[0027] Satellite camera parameters, including lens and detector information, decomposed from the satellite attitude and orbit dynamics model, and ground environment parameters, including atmospheric and ground environment information, decomposed from the complex imaging link anomaly image shift compensation model, are both sent to the optical camera imaging simulation module of the simulation platform. Through the object-image mapping model under anomaly image shift compensation and the variable-frequency high-integral-series scanning imaging model, geometric link models and radiometric response models are constructed respectively. This allows for full-link imaging simulation of a high-resolution wide-swath camera, generating virtual degraded images to predict the satellite's attitude and orbit state. The generated virtual degraded image is expressed by the formula:

[0028] (1);

[0029] in, These are degraded images of the target object generated by the Earth's surface environment system, atmospheric system, satellite attitude and orbit system, and camera system, respectively. This is the final generated virtual degraded image.

[0030] In the Earth's surface environment system, space is divided into the near-surface space region from the target point to the lower atmosphere, and the transmission of light occurs in this process. It can be represented as ,in, These are degraded images generated after being affected by target contrast, ground reflectivity, ground elevation, and Earth curvature deflection.

[0031] for For most remote sensing imaging systems, the contrast between the target point and the background received by the detector is defined as:

[0032] (2);

[0033] In the formula, and These represent the radiation levels received by the detector from the target location and the background, respectively.

[0034] The method for calculating ground reflectivity is based on the wavelength of ground landmarks. to Taking the range as an example, its average reflectance within the range It can be obtained using the following formula:

[0035] (3);

[0036] In the formula, wavelength arrive Average reflectance within the range, For ground attractions in the band The amount of reflected radiation at that location. For reference, the whiteboard is in the band. The amount of reflected radiation at that location.

[0037] for , and These represent the camera's focal length and the orbital altitude of the space camera, respectively. The point is the difference in elevation. The actual tourist attractions for The distance between the corresponding image point and the center of the image plane is: , The tilt angle, representing the camera's tilt, is the positional deviation on the camera's image plane caused by the terrain's undulations. It can be written as:

[0038] (4);

[0039] in, The difference in elevation; Given a side sway, the angle between any point on the image plane and the actual object and the line connecting the camera to the Earth's center is given. Side swing angle and difference.

[0040] The terrain features of the locations of ground attractions can be obtained by querying existing Digital Elevation Models (DEMs).

[0041] The deviation in elevation is usually calculated using the following formula:

[0042] (5);

[0043] In the formula, Location in DEM Elevation of the location For reference position At elevation, For position The height difference at the location, The number of samples collected. The average of all height differences. The standard deviation of the height difference. The root mean square error of the difference is given.

[0044] for , and These represent the orbital altitude of the space camera and the Earth's radius, respectively. This represents the height difference between the horizontal reference plane and the actual ground landmark. Therefore, the positional deviation caused by the curvature of the Earth It can be represented as:

[0045] (6);

[0046] At this point, we can obtain images of the degraded surface environment. Then, the image needs to be processed by the atmospheric space module to obtain the degraded image. In this module, It can be represented as , They are respectively Degraded images generated after being affected by atmospheric refractive index and surface environment.

[0047] for Atmospheric refractive index The following formula can be used for calculation:

[0048] (7);

[0049] for , have:

[0050] (8);

[0051] In the formula, Therefore, the corresponding atmospheric refractive index can be calculated given known atmospheric conditions; where, This represents the air pressure after removing the pressure of water vapor from the atmosphere. Atmospheric pressure, The pressure is for water vapor, and the unit is Pascal. The thermal temperature of the atmosphere is expressed in Kelvin. The wavelength of the incident light is expressed in micrometers.

[0052] set up Represents a space camera. Represents the Earth's core. Represents the ideal imaging point, Represents the actual imaging point. Indicates the side tilt angle of the space camera; Represents the spatial refractive index, These represent the sequence of steps taken from the space camera to the ground region. The atmosphere; Represents the Earth's radius. Representing the number in sequence The distance from the lower boundary of the atmosphere to the Earth's center; assuming , .

[0053] for The deflection of the imaging light rays on the Earth's surface It can be represented as:

[0054] (9);

[0055] At this point, a degraded image of the satellite after passing through atmospheric space can be obtained. Following this, the impact of satellite attitude and orbit on image acquisition needs to be considered to obtain the degraded image. . It can be represented as ,in, These are degraded images generated after being affected by the satellite's attitude and orbit.

[0056] for The transformation matrix can be obtained using quaternions, thus providing the satellite's perspective of the target object. According to the definition of a quaternion, the quaternion of the satellite's initial body coordinate system relative to the body coordinate system at the start of active pushbroom is... It can be represented as:

[0057] (10);

[0058] in, To observe the angle between the optical axis and the initial optical axis at the start of the satellite's active pushbroom, It is a unit vector perpendicular to the optical axis and the initial optical axis at the start of active pushbroom.

[0059] for The process of a satellite platform orbiting the Earth can be considered a simple two-body problem. Its motion satisfies Kepler's laws of planetary motion. Therefore, for a given orbital plane, the six fundamental numbers of the orbit are often used to describe it, namely, the semi-major axis of the orbit, the orbital eccentricity, the orbital inclination, the right ascension of the ascending node, the argument of the near-surface, and the true anomaly.

[0060] At this point, we can obtain the degraded image generated after passing through the satellite attitude and orbit system. Finally, the image needs to be processed by a space-based optical camera system to obtain the final degraded image. The degraded image processed by the camera system... It can be represented as ,in, These are degraded images affected by camera focal length and distortion.

[0061] for The object needs to undergo coordinate transformation through the objective lens to obtain the final image:

[0062] (11);

[0063] In the formula, The focal length of the objective lens. , These are the coordinates of the object before and after the coordinate transformation through the objective lens, respectively.

[0064] for Since radial and tangential distortions occur simultaneously, they must be considered together. The combined distortion can be expressed as:

[0065] (12);

[0066] in, The radial distortion coefficient is... The tangential distortion coefficient is... Coordinates Distance to the center point of the image plane These are the original coordinates before distortion occurred. These are the actual coordinates of the corresponding point on the image plane when distortion exists.

[0067] The focal plane data processing module is connected to both the mechanism control module and the optical camera imaging simulation module. It receives the execution parameters of the imaging mission satellite platform and payload mechanism during the simulation process. Through geometric correction models, radiometric correction models, and detector MTF models, it performs real-time comparisons of the imaging quality between the virtual degraded image and the actual image captured by the on-orbit camera. Based on the comparison results, it performs digital twin model correction. The correction process includes: selecting whether to keep the execution parameters unchanged, identify the main parameters, or identify all parameters based on the comparison results between the virtual degraded image and the actual image. When parameter identification is selected, the main or all parameters of the digital twin model are updated according to the selected identification strategy to achieve model optimization.

[0068] like Figure 2 As shown, real-time data transmission occurs between the physical and digital virtual components of the spacecraft optical camera. The satellite attitude and orbit data of the spacecraft camera are transmitted telemetry data and commands to the on-orbit camera's actual captured images. Simultaneously, the satellite attitude and orbit data is transmitted to the digital virtual component, i.e., the digital optical camera virtual component. Based on its remote control commands, the digital virtual component performs digital camera modeling and simulation. The simulated data is then returned to the physical satellite for attitude and orbit adjustments. The digital camera model generates a virtual degraded image, and the images captured by the physical camera are compared with the virtual degraded image of the digital virtual component in real time to assess image quality. Simultaneously, the satellite attitude and orbit data transmitted to both the physical and virtual components are compared in real time to assess imaging mission parameters, and digital twin model correction is performed based on the differences between the two. During the identification process, parameters can be maintained, main parameter identification can be performed, or full parameter identification can be performed based on image quality. Selective updates to full parameters or main parameters can be performed to achieve model optimization and fault diagnosis.

[0069] The corrected mechanism control model parameters and imaging mission operating parameters are uploaded back to the ultra-high line frequency low crosstalk integrated electronic module to generate simulation platform data. The imaging mission operating parameters include the simulated image and auxiliary data under the current imaging parameters. The auxiliary data includes satellite attitude and orbit information, actuator motion, and current imaging mission parameters (line frequency, integration technique, gain).

[0070] The ultra-high line frequency low crosstalk integrated electronic module transmits simulation platform data back to the satellite's ground inspection system. The satellite receives control commands from the ground inspection system and then images ground targets again according to the plan.

[0071] The imaging mission parameters of the perceived physical satellite camera and the virtual satellite camera are compared again with the image data and auxiliary data. Based on the online data, the parameters of the digital twin imaging model are identified, and the imaging model parameters / master parameters are selectively updated to obtain the improved simulation platform data.

[0072] The aforementioned optical payload physical digital twin simulation system transmits and compares physical optical payload data with simulation platform data online, and improves various parameters of the physical optical payload physical digital twin model in real time. This results in a high-precision physical satellite camera model, enabling real-time simulation of the physical satellite, accurate prediction of the physical satellite's motion, and higher image quality obtained by the satellite camera.

[0073] This invention simplifies the satellite payload imaging link and object-image mapping relationship, and compares the data collected by the physical entity with the data of the virtual twin online to adjust the imaging mission parameters of the twin in real time, thereby improving the simulation accuracy of the digital virtual entity. It provides an effective way to realize real-time status monitoring and control command verification of satellite payloads, and solves the problems of existing simulation systems being unable to achieve real-time synchronization between ground object systems and digital models and the time delay in output. As a result, a 1:1 real-mount digital twin simulation system is obtained, which greatly improves the imaging quality of space payloads.

[0074] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A digital twin simulation system for optical payload installation, characterized in that, include: The satellite digital virtual entity is connected to the optical payload full digital virtual simulation platform and is used to initialize the optical payload full digital virtual simulation platform. The initialization data includes the onboard interaction status, ground object environmental parameters, camera parameters and imaging modes. An external interface module connects to the fully digital virtual simulation platform for optical payloads, used for image quality analysis and displaying simulation results; A fully digital virtual simulation platform for optical payloads, including: The ultra-high line frequency low crosstalk integrated electronic module is used to receive and decompose instructions from the ground inspection system, calculate the satellite attitude and orbit dynamics model, the complex imaging link irregular image shift compensation model and the spaceborne cooperative imaging control model, and transmit the generated simulation platform data back to the ground inspection system. The mechanism control module, connected to the ultra-high line frequency low crosstalk integrated electronic module, is used to receive the desired motion attitude information of the actuator decomposed from the spaceborne collaborative imaging control model, and to verify and plan the focusing and biasing flow composite mechanism. The optical camera imaging simulation module is connected to the ultra-high line frequency low crosstalk integrated electronic module. It is used to receive satellite camera parameters decomposed from the satellite attitude and orbit dynamics model and ground object environmental parameters decomposed from the complex imaging link irregular image shift compensation model. It performs full-link imaging simulation by constructing a geometric link model and a radiation response model to generate virtual degraded images. The focal plane data processing module is connected to both the mechanism control module and the optical camera imaging simulation module. It receives the execution parameters of the imaging mission satellite platform and payload mechanism during the simulation process, performs real-time comparison of the imaging quality between the virtual degraded image and the real image captured by the on-orbit camera, and performs digital twin model correction based on the comparison results. The corrected mechanism control model parameters and imaging mission working parameters are then uploaded back to the ultra-high frequency low crosstalk integrated electronic module to generate simulation platform data and transmit it back to the ground inspection system. The satellite receives control commands from the ground inspection system and images the ground targets again according to the plan.

2. The optical payload physical digital twin simulation system according to claim 1, characterized in that, The full-link imaging simulation sequentially includes modeling the degradation processes of the surface environment system, atmospheric system, satellite attitude and orbit system, and camera system.

3. The optical payload physical digital twin simulation system according to claim 2, characterized in that, Generated virtual degraded image for: （1）； in, , These are degraded images generated after being affected by target contrast, ground reflectivity, ground elevation, and Earth curvature deflection, respectively. , Degraded images Degraded images generated after being affected by atmospheric refractive index and surface environment; , Degraded images Degraded images generated due to the influence of satellite attitude and orbit; , Degraded images Degraded images affected by camera focal length and distortion.

4. The optical payload physical digital twin simulation system according to claim 1, characterized in that, The focal plane data processing module performs real-time comparison of imaging quality between the virtual degraded image and the real-world image captured by the on-orbit camera using geometric correction model, radiometric correction model, and detector MTF model.

5. The optical payload physical digital twin simulation system according to claim 1, characterized in that, The process of digital twin model correction by the focal plane data processing module includes: based on the comparison results of the imaging quality of the virtual degraded image and the real image, selecting whether to keep the execution parameters unchanged, identify the main parameters, or identify all parameters. When parameter identification is selected, the main parameters or all parameters of the digital twin model are updated according to the selected identification strategy to achieve model optimization.

6. The optical payload physical digital twin simulation system according to claim 1, characterized in that, The external interface module performs image quality analysis, including spatial resolution analysis, dynamic transfer function testing, line frequency testing, and swath width analysis.

7. The optical payload physical digital twin simulation system according to claim 1, characterized in that, The external interface module uses a CAN bus or RS422 communication interface.

8. The optical payload physical digital twin simulation system according to claim 1, characterized in that, The onboard interactive state includes the payload's initial imaging time, imaging duration, target latitude and longitude, satellite attitude and orbit status, and camera installation attitude. The environmental parameters of the ground features include solar radiation, atmospheric transport, and targets; The camera parameters include TDI integration series, imaging spectrum, spectral response, gain, bias, quantization, and compression ratio; The imaging modes include push-broom and swing-broom.

9. The optical payload physical digital twin simulation system according to claim 1, characterized in that, Satellite camera parameters include lens and detector information, while ground environment parameters include atmospheric models and ground environment information.

10. The optical payload physical digital twin simulation system according to claim 1, characterized in that, The geometric link model is an object-image mapping model under irregular image shift compensation, and the radiation response model is a variable-frequency high-integral-level scanning imaging model.

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