A digital twin simulation test system for space target visual navigation system

Abstract

The present application discloses a digital twin simulation test system for a space target visual navigation system, which relates to the field of ground simulation test technology. The system includes: a physical simulation test subsystem and a digital simulation test subsystem. The physical simulation test subsystem includes a space scene physical simulation module, a physical optical imaging module and a physical information processing module. The digital simulation test subsystem includes a space scene digital simulation module, a digital optical imaging module and a digital information processing module. The space scene physical simulation module and the space scene digital simulation module are used to simulate the on-orbit optical characteristics, on-orbit illumination state and relative motion state of a real space target. The physical optical imaging module and the digital optical imaging module are used to simulate the imaging process of a real optical imaging module. The physical information processing module and the digital information processing module are used to simulate the processing process of a real information processing module. The present application can better perform ground simulation testing on a space target visual navigation system.

Description

Technical Field

[0001] The present application relates to the field of ground simulation testing technology, and in particular to a digital twin simulation test system for a space target visual navigation system. Background Art

[0002] The space target visual navigation system realizes space target navigation by extracting the feature information of the space target from the measurement image and further calculating the navigation parameters such as the relative position of the space target.

[0003] During the development and on-orbit operation phases of space target visual navigation systems, ground-based simulation testing methods are required to comprehensively test and verify the detection capabilities, algorithm solution accuracy, and navigation measurement stability of the space target visual navigation system to ensure the smooth execution of on-orbit missions. Currently, the main ground-based simulation testing methods include physical simulation testing and digital simulation testing. The physical simulation testing method requires the construction of a full-scale physical model of the space target in the laboratory, equipped with a space environment simulation system such as physical lighting and motion. The simulation test results are generally consistent with the actual on-orbit conditions, but are significantly limited by site and cost conditions and are generally only applicable to typical critical mission testing. The digital simulation testing method uses digital scene design and modeling to digitally simulate the space target imaging and navigation information solution process. This method has the advantages of low testing cost and the ability to cover all scenario mission conditions. However, the results of digital simulation tests are still significantly different from those of physical simulation tests, and cannot fully reflect the impact of complex space environments on the image texture and pose solution accuracy of space targets.

[0004] Based on this, there is an urgent need for a system that can better perform ground simulation testing of space target visual navigation systems. Summary of the Invention

[0005] The purpose of this application is to provide a digital twin simulation test system for a space target visual navigation system, which can better perform ground simulation tests on the space target visual navigation system.

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

[0007] In a first aspect, the present application provides a digital twin simulation test system for a space target visual navigation system, the digital twin simulation test system for the space target visual navigation system comprising: a physical simulation test subsystem and a digital simulation test subsystem, the physical simulation test subsystem being used to perform physical simulation of the space target visual navigation system, the digital simulation test subsystem being a digital twin model of the physical simulation test subsystem, and the digital simulation test subsystem being used to perform digital simulation of the space target visual navigation system;

[0008] The physical simulation test subsystem includes a space scene physical simulation module, a physical optical imaging module, and a physical information processing module; the space scene physical simulation module is used to simulate the on-orbit optical characteristics, on-orbit illumination state, and relative motion state of a real space target through a physical model; the physical optical imaging module is used to image the space target through the physical model to obtain a physical simulation image of the space target, so as to simulate the imaging process of the real optical imaging module; the physical information processing module is used to process the physical simulation image of the space target through the physical model to obtain the relative position and posture of the space target, so as to simulate the processing process of the real information processing module;

[0009] The digital simulation test subsystem includes a space scene digital simulation module, a digital optical imaging module and a digital information processing module; the space scene digital simulation module is used to simulate the on-orbit optical characteristics, on-orbit illumination state and relative motion state of a real space target through a digital model; the digital optical imaging module is used to image the space target through a digital model to obtain a digital simulation image of the space target, so as to simulate the imaging process of the real optical imaging module; the digital information processing module is used to process the digital simulation image of the space target through a digital model to obtain the relative position and posture of the space target, so as to simulate the processing process of the real information processing module.

[0010] Optionally, the space scene physical simulation module includes a space target model, a solar simulator and a space relative motion simulation manipulator;

[0011] The geometric structure and surface material of the space target model are identical to those of the real space target, so as to simulate the on-orbit optical characteristics of the real space target;

[0012] The solar simulator uses a parallel light source with the same spectral characteristics as the sun outside the atmosphere, and its position can be adjusted to simulate the on-orbit illumination state of a real space target;

[0013] The space target model and the real optical imaging module are both installed on the space relative motion simulation robotic arm; the space relative motion simulation robotic arm is used to adjust the relative posture of the space target model relative to the real optical imaging module to simulate the relative motion state of the real space target.

[0014] Optionally, the space relative motion simulation robotic arm includes a target motion simulation six-degree-of-freedom robotic arm and a measurement system motion simulation six-degree-of-freedom robotic arm, the space target model is installed on the target motion simulation six-degree-of-freedom robotic arm, and the real optical imaging module is installed on the measurement system motion simulation six-degree-of-freedom robotic arm, the target motion simulation six-degree-of-freedom robotic arm is used to adjust the posture of the space target model, and the measurement system motion simulation six-degree-of-freedom robotic arm is used to adjust the posture of the real optical imaging module to adjust the relative posture of the space target model relative to the real optical imaging module, so as to simulate the relative motion state of the real space target.

[0015] Optionally, the space scene physical simulation module also includes an approximate motion simulation guide rail, and the target motion simulation six-degree-of-freedom robotic arm and the measurement system motion simulation six-degree-of-freedom robotic arm are both installed on the approximate motion simulation guide rail; the approximate motion simulation guide rail is used to adjust the relative distance between the space target model and the physical optical imaging module to adjust the relative posture of the space target model relative to the physical optical imaging module, so as to simulate the relative motion state of the real space target.

[0016] Optionally, the physical optical imaging module includes several optical cameras; the physical information processing module includes a data solution information processing box, and the data solution information processing box has an algorithm for solving the relative posture information of the space target based on the physical simulation image of the space target.

[0017] Optionally, the space scene digital simulation module includes a digital model of relative motion of space targets, a digital model of geometric structure of space targets, a digital model of optical characteristics of space targets, and a digital model of space sunlight;

[0018] The digital model of relative motion of the space target is used to obtain the simulated position and posture of the real space target, the real optical imaging module and the real sun based on the orbital dynamics model in real time simulation calculation, so as to simulate the relative motion state of the real space target;

[0019] The digital model of the geometric structure of the space target includes the position and surface material of each triangular facet obtained by meshing the surface of the geometric structure model of the space target based on the simulated position of the real space target; the position includes the three-dimensional coordinates of each vertex of the triangular facet and the three-dimensional coordinates of the normal vector of the triangular facet;

[0020] The digital model of the optical characteristics of the space target is used to measure the reflectance and perform parameterized fitting of the bidirectional reflectance distribution function for each surface material to obtain the optical characteristic model parameters of the surface material, so as to simulate the on-orbit optical characteristics of the real space target;

[0021] The space solar illumination digital model is used to treat the real sun as an equivalent black body with a temperature of 5900K, calculate the real sun's light source radiation brightness in the visible spectrum using Planck's formula, and determine the direction vector of the sun's rays based on the simulated position of the real space target and the simulated position of the real sun, so as to simulate the on-orbit illumination state of the real space target.

[0022] Optionally, the digital optical imaging module is used to generate a direction vector of the tracking light for each pixel, determine the triangular surface element that intersects with the tracking light of each pixel based on the simulated posture of the real space target, the simulated posture of the real optical imaging module and the digital model of the geometric structure of the space target, determine the radiation brightness of each pixel based on the surface material of the triangular surface element that intersects with the tracking light of each pixel, the digital model of the optical properties of the space target and the digital model of space sunlight, obtain a radiation brightness image, perform distortion simulation processing and radiation quantization simulation processing on the radiation brightness image, and obtain a digital simulation image of the space target.

[0023] Optionally, the digital information processing module adopts an algorithm for solving the relative posture information of the space target based on the digital simulation image of the space target; wherein, the algorithm for solving the relative posture information of the space target based on the digital simulation image of the space target is the same as the algorithm for solving the relative posture information of the space target based on the physical simulation image of the space target.

[0024] Optionally, the physical communication interface and communication protocol of the physical optical imaging module are the same as the physical communication interface and communication protocol of the digital optical imaging module, and the physical communication interface and communication protocol of the physical information processing module are the same as the physical communication interface and communication protocol of the digital information processing module.

[0025] Optionally, the working modes of the digital twin simulation test system of the space target visual navigation system include: full physical simulation test, digital imaging physical processing simulation test, physical imaging digital processing simulation test and full digital simulation test;

[0026] When conducting a full-physical simulation test, the digital twin simulation test system of the space target visual navigation system includes a space scene physical simulation module, a physical optical imaging module, and a physical information processing module connected in sequence;

[0027] When conducting a digital imaging physical object processing simulation test, the digital twin simulation test system of the space target visual navigation system includes a space scene digital simulation module, a digital optical imaging module and a physical object information processing module connected in sequence;

[0028] When conducting a physical imaging digital processing simulation test, the digital twin simulation test system of the space target visual navigation system includes a space scene physical simulation module, a physical optical imaging module, and a digital information processing module connected in sequence;

[0029] When conducting a full digital simulation test, the digital twin simulation test system of the space target visual navigation system includes a space scene digital simulation module, a digital optical imaging module and a digital information processing module connected in sequence.

[0030] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0031] The present application provides a digital twin simulation test system for a space target visual navigation system, including: a physical simulation test subsystem and a digital simulation test subsystem. The physical simulation test subsystem includes a space scene physical simulation module, a physical optical imaging module and a physical information processing module. The digital simulation test subsystem includes a space scene digital simulation module, a digital optical imaging module and a digital information processing module. The space scene physical simulation module and the space scene digital simulation module are used to simulate the on-orbit optical characteristics, on-orbit lighting state and relative motion state of the real space target. The physical optical imaging module and the digital optical imaging module are used to image the space target to simulate the imaging process of the real optical imaging module. The physical information processing module and the digital information processing module are used to solve the relative position and posture of the space target to simulate the processing process of the real information processing module. That is, the physical simulation test subsystem is used to perform physical simulation of the space target visual navigation system, and the digital simulation test subsystem is a digital twin model of the physical simulation test subsystem. The digital simulation test subsystem is used to digitally simulate the space target visual navigation system. This application achieves a balance between authenticity and coverage of ground simulation tests of space target visual navigation systems by combining physical simulation and digital simulation. The digital simulation test subsystem constructed through digital twins realizes the virtual-reality mapping of the physical simulation test subsystem. Compared with traditional physical simulation test methods, the test scene coverage is wider, and compared with traditional digital simulation test methods, the simulation realism is higher, so that ground simulation tests of space target visual navigation systems can be better carried out. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. 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 creative work.

[0033] Figure 1A schematic diagram of the composition of a digital twin simulation test system for a space target visual navigation system provided in Example 1 of the present application.

[0034] Figure 2 This is a structural diagram of the space scene physical simulation module provided in Example 1 of the present application.

[0035] Figure 3 Schematic diagram of the flow of the space target relative pose solution algorithm provided in Example 1 of the present application.

[0036] Figure 4 Schematic diagram of the digital simulation framework of the working timing of the algorithm used in the physical information processing module provided in Example 1 of the present application.

[0037] Figure 5 Schematic diagram of the workflow of the full-physical simulation test provided in Example 1 of the present application.

[0038] Figure 6 This is a schematic diagram of the workflow of the digital imaging physical object processing simulation experiment provided in Example 1 of the present application.

[0039] Figure 7 This is a schematic diagram of the workflow of the physical imaging digital processing simulation experiment provided in Example 1 of the present application.

[0040] Figure 8 Schematic diagram of the workflow of the fully digital simulation test provided in Example 1 of the present application. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0042] Example 1

[0043] The space target visual navigation system usually includes an optical imaging module and an information processing module. Both the optical imaging module and the information processing module are installed on the navigation space target that needs to be navigated. Its working process is as follows: when the navigation space target is in orbit, the optical imaging module performs optical imaging on the space target outside the navigation space target to obtain the space target image. The information processing module further solves the relative position information of the space target relative to the navigation space target by extracting features from the space target image. The position information includes position information and attitude information. The measured relative position information is provided to the satellite platform corresponding to the navigation space target to navigate and control the navigation space target, so as to avoid collision or rendezvous with the space target (such as a close approach rendezvous scenario of a space target).

[0044] In order to better realize the ground simulation test of the space target visual navigation system, this embodiment designs a digital twin simulation test system of the space target visual navigation system, which is used to simulate the on-orbit measurement and solution process of the above-mentioned space target visual navigation system on the ground, so as to perform ground simulation test on the space target visual navigation system and verify the measurement accuracy and measurement adaptability of the space target visual navigation system. Figure 1 As shown, the digital twin simulation test system of the space target visual navigation system of this embodiment includes: a physical simulation test subsystem and a digital simulation test subsystem. Both subsystems contain three types of modules: space scene simulation, optical imaging, and information processing. The physical simulation test subsystem is used to perform physical simulation of the space target visual navigation system, and the digital simulation test subsystem is a digital twin model of the physical simulation test subsystem. The digital simulation test subsystem is used to digitally simulate the space target visual navigation system. Among them, the physical simulation test subsystem can realize physical simulation tests of typical space target visual navigation tasks that are close to the actual on-orbit state. The digital simulation test subsystem can supplement the on-orbit mission conditions that the physical simulation test subsystem cannot currently cover through digital simulation.

[0045] In this embodiment, the physical simulation test subsystem includes a space scene physical simulation module, a physical optical imaging module, and a physical information processing module. The following is a detailed introduction to each module:

[0046] (1) Space scene physical simulation module

[0047] The space scene physical simulation module is used to simulate the on-orbit optical characteristics, on-orbit lighting conditions and relative motion conditions of real space targets through physical models, which can achieve a relatively realistic simulation effect.

[0048] like Figure 2 As shown, the space scene physical simulation module includes a space target model, a solar simulator and a space relative motion simulation robotic arm.

[0049] The space target model is constructed based on the geometry of a real space target. Its surface uses the same surface materials (also known as surface textures, such as thermal control materials) as the real space target to accurately simulate the optical reflection characteristics of the real space target. Therefore, the geometry and surface materials of the space target model are identical to those of the real space target, simulating the on-orbit optical properties of the real space target.

[0050] The solar simulator uses a parallel light source with the same spectral characteristics as the sun outside the atmosphere, and its position can be adjusted. It is used to realistically simulate the on-orbit solar illumination state of a real space target in order to simulate the on-orbit illumination state of a real space target.

[0051] The space target model and the physical optical imaging module are both installed on a space relative motion simulation robotic arm. The space relative motion simulation robotic arm is used to adjust the relative posture of the space target model relative to the physical optical imaging module to simulate the relative motion state of the real space target.

[0052] Specifically, the space relative motion simulation robot includes a target motion simulation six-degree-of-freedom robot and a measurement system motion simulation six-degree-of-freedom robot. The space target model is installed on the target motion simulation six-degree-of-freedom robot, and the real optical imaging module is installed on the measurement system motion simulation six-degree-of-freedom robot. The target motion simulation six-degree-of-freedom robot is used to adjust the posture of the space target model, and the measurement system motion simulation six-degree-of-freedom robot is used to adjust the posture of the real optical imaging module, so as to simulate the spatial relative position and posture relationship between the real space target and the real optical imaging module by controlling the movement of the two six-degree-of-freedom robots, and adjust the relative posture of the space target model relative to the real optical imaging module to simulate the relative motion state of the real space target.

[0053] When it is necessary to simulate the relative approach relationship between the real space target and the real optical imaging module in a large range of space, it is difficult to achieve corresponding adjustments by adjusting the two six-degree-of-freedom robotic arms. Therefore, the space scene physical simulation module of this embodiment also includes an approach motion simulation guide rail, which is a guide rail for controlling the relative approach motion of the two six-degree-of-freedom robotic arms. The target motion simulation six-degree-of-freedom robotic arm and the measurement system motion simulation six-degree-of-freedom robotic arm are both installed on the approach motion simulation guide rail. The approach motion simulation guide rail is used to adjust the relative distance between the space target model and the real optical imaging module to adjust the relative position of the space target model relative to the real optical imaging module to simulate the relative motion state of the real space target.

[0054] (2) Physical optical imaging module

[0055] The physical optical imaging module is used to image the space target through the physical model to obtain a physical simulation image of the space target, so as to simulate the imaging process of the real optical imaging module.

[0056] The physical optical imaging module is generally an optical camera installed on the navigation space target. The optical camera is used to detect and image the space target model in the space scene physical simulation module to obtain a physical simulation image of the space target.

[0057] Based on this, in this embodiment, the physical optical imaging module includes several optical cameras.

[0058] (3) Physical information processing module

[0059] The physical information processing module is used to process the physical simulation image of the space target through the physical model to obtain the relative position and posture of the space target to simulate the processing process of the real information processing module.

[0060] The physical information processing module is generally a data solution information processing box installed on the navigation space target. The data solution information processing box is used to receive the physical simulation image of the space target and obtain the relative position information of the space target through the space target relative position solution algorithm. Figure 3 As shown in Figure 1, the steps of the space target relative pose solution algorithm include:

[0061] 1) Perform image preprocessing on the received space target physical simulation image, which includes image processing operations such as distortion correction, image filtering to remove noise and image enhancement.

[0062] 2) Extract the space target's characteristic components from the image obtained after image preprocessing. Specifically, the space target's docking ring and other characteristic components are extracted from the image through operations such as threshold segmentation, contour extraction, and characteristic shape screening. The characteristic parameters of these components, such as the center point and axis length, are calculated. It should be noted that when the characteristic component is circular, the axis length is the diameter; when the characteristic component is elliptical, the axis length is the length of the major and minor axes.

[0063] 3) Correct feature recognition is achieved by cross-validating the feature parameters extracted from the simulated images of the space target taken by multiple optical cameras. The feature parameters corresponding to each optical camera are then used as input to solve the relative position and pose of the space target through multi-view measurement methods. The effectiveness of the solution is evaluated and the relative position and pose measurement results are output.

[0064] Based on this, in this embodiment, the physical information processing module includes a data solution information processing box, which has an algorithm for solving the relative posture information of the space target based on the physical simulation image of the space target (i.e., the space target relative posture solution algorithm).

[0065] In this embodiment, the digital simulation test subsystem includes a space scene digital simulation module, a digital optical imaging module, and a digital information processing module. The following is a detailed introduction to each module:

[0066] (1) Space scene digital simulation module

[0067] The space scene digital simulation module is used to simulate the on-orbit optical characteristics, on-orbit illumination status and relative motion status of real space targets through digital models.

[0068] The space scene digital simulation module simulates the relative position data of real space targets and real optical imaging modules in real time by constructing a digital model of the relative motion of space targets. At the same time, it constructs a digital model of the geometric structure of space targets, a digital model of the optical characteristics of space targets, and a digital model of space sunlight, providing scene element models and data for digital imaging simulation.

[0069] Based on this, in this embodiment, the space scene digital simulation module includes a digital model of the relative motion of space targets, a digital model of the geometric structure of space targets, a digital model of the optical characteristics of space targets, and a digital model of space sunlight.

[0070] The relative position and posture data of the real-space target and the real optical imaging module are simulated and calculated using an orbital dynamics model. Specifically, by setting the six orbital elements of the real-space target and the motion equation of the real optical imaging module relative to the real-space target, combined with the simulation time and frequency set in the digital simulation experiment, the position and posture of the real-space target, the real optical imaging module, and the real sun in the geocentric inertial coordinate system are calculated in real time. Based on this, the digital model of the relative motion of the space target is used to simulate the position and posture of the real-space target, the real optical imaging module, and the real sun in real time based on the orbital dynamics model, thereby simulating the relative motion state of the real-space target.

[0071] The digital model of the geometric structure of the space target is defined by a discretized triangular facet mesh. Specifically, the surface of the geometric structure module of the space target (which can be a design model of the geometric structure of the space target or a three-dimensional scanning model of the geometric structure of the space target) is meshed with triangular facets through meshing tool software. Each triangular facet is represented by the three-dimensional coordinates of three vertices and the three-dimensional coordinates of the normal vector. The triangular facets are classified and labeled according to the surface material type, that is, triangular facets with the same surface material type are stored in a material set, and the material set is labeled as a specific surface material type. Based on this, the digital model of the geometric structure of the space target includes the position and surface material of each triangular facet obtained by meshing the surface of the geometric structure model of the space target based on the simulated posture of the real space target. The position includes the three-dimensional coordinates of each vertex of the triangular facet and the three-dimensional coordinates of the normal vector of the triangular facet.

[0072] The digital model of the optical characteristics of space targets is defined using a bidirectional reflectance distribution function (BRDF). Specifically, the hemispherical reflection characteristics (i.e., reflection coefficient) of the surface materials of space targets are measured and parameterized by the BRDF to obtain the optical characteristic model parameters of different surface materials. These parameters are then annotated in the corresponding material set in the digital model of the geometric structure of the space target. When measuring the reflection coefficient, the reflection coefficient is measured at different angles. Different angles include the azimuth and elevation angles of the incident angle of the sun's rays, as well as the azimuth and elevation angles of the exit angle of the sun's rays. The final optical characteristic model parameters are the model parameters of the model obtained by fitting different angles and reflection coefficients. Through this optical characteristic model parameter, the corresponding reflection coefficient can be calculated based on different angles. Based on this, the digital model of the optical characteristics of space targets is used to measure the reflection coefficient and parameterize the bidirectional reflectance distribution function for each surface material to obtain the optical characteristic model parameters of the surface material, so as to simulate the on-orbit optical characteristics of real space targets.

[0073] The digital model of space solar illumination is defined using the characteristics of a parallel light source. Specifically, the real sun is considered to be an equivalent black body with a temperature of 5900K. The Planck formula is used to calculate the radiant brightness of the real sun in the visible spectrum. The three-dimensional direction vector of the real sun's rays is calculated based on the spatial position of the real sun in the simulated pose and the spatial position of the real space target in the simulated pose. Based on this, the digital model of space solar illumination is used to treat the real sun as an equivalent black body with a temperature of 5900K, calculate the radiant brightness of the real sun in the visible spectrum using the Planck formula, and determine the direction vector of the sun's rays based on the simulated pose of the real space target and the simulated pose of the real sun, in order to simulate the on-orbit illumination state of the real space target.

[0074] (2) Digital optical imaging module

[0075] The digital optical imaging module is used to image the space target through a digital model to obtain a digital simulation image of the space target, so as to simulate the imaging process of the real optical imaging module.

[0076] The digital optical imaging module is used to digitally simulate the imaging process of an optical camera. It receives the digital model data of the above-mentioned space scene digital simulation module and uses the ray tracing method to perform digital imaging simulation calculations of space targets to obtain digital simulation images of space targets. The specific process is as follows:

[0077] 1) Generate tracking rays for each pixel based on the geometric imaging model of the optical camera. Calculate the intersection of the tracking rays with the real space target and the corresponding triangular facets based on the digital model of the space target's geometric structure, the real space target, and the relative pose of the real optical imaging module.

[0078] 2) Based on the surface material of the triangular facet corresponding to the intersection point, the corresponding optical characteristic model parameters are called, and the radiance of the tracking light is calculated in combination with the digital model of spatial sunlight. Specifically, the reflection coefficient is calculated based on the optical characteristic model parameters, and then the product of the radiance of the sun's light source and the reflection coefficient is calculated to obtain the radiance. This process is repeated to calculate the radiance of each pixel and obtain a radiance image.

[0079] 3) The radiation brightness image is subjected to distortion simulation and radiation quantization simulation (i.e., grayscale simulation) to finally generate a digital simulation image of the space target.

[0080] In distortion simulation, the distortion simulation model parameters, including the optical camera's focal length, principal point position, and distortion coefficient, are calibrated through camera parameter calibration tests. The optical camera images a checkerboard calibration plate of known geometric dimensions at different positions and postures to obtain calibration images. Within the calibration images, the checkerboard corners are extracted and identified. Using the theoretical parameters of the optical camera as initial values, this extracted corner information is fed into the calibration model for iterative optimization. This allows the actual distortion simulation model parameters of the optical camera to be calculated, ensuring that the distortion effects of the digital simulated image of the space target are consistent with those of the physical simulated image of the space target.

[0081] In radiometric quantization simulation, noise simulation model parameters include the noise mean and standard deviation, while radiometric response quantization model parameters are grayscale quantization coefficients. These parameters are calibrated through camera radiometric calibration tests. An optical camera measures and images uniform elements of an integrating sphere. The sphere's outgoing radiation brightness is adjusted to obtain different measurement images. Through statistical analysis of the mean and standard deviation distribution of the measured image pixel grayscale values ​​at different integrating sphere outgoing radiation brightnesses, simulation model parameters such as the noise mean, standard deviation, and grayscale quantization coefficient are calculated. This ensures that the noise and radiometric response effects of the digitally simulated space target image are consistent with those of the physical space target image.

[0082] Based on this, in this embodiment, the digital optical imaging module is used to generate the direction vector of the tracking light for each pixel, and based on the simulated posture of the real space target, the simulated posture of the real optical imaging module and the digital model of the geometric structure of the space target, determine the triangular surface element that intersects with the tracking light of each pixel, and determine the radiation brightness of each pixel based on the surface material of the triangular surface element that intersects with the tracking light of each pixel, the digital model of the optical characteristics of the space target and the digital model of space sunlight to obtain a radiation brightness image, and perform distortion simulation processing and radiation quantization simulation processing on the radiation brightness image to obtain a digital simulation image of the space target.

[0083] (3) Digital information processing module

[0084] The digital information processing module is used to process the digital simulation image of the space target through the digital model to obtain the relative position and posture of the space target, so as to simulate the processing process of the real information processing module.

[0085] The digital information processing module is used for the image processing process of the digital simulation data solution information processing box, receives the digital simulation image of the space target, and solves the relative posture information of the space target through the space target relative posture solution algorithm. At this time, the solution process of the space target relative posture solution algorithm is completely consistent with the solution process of the space target relative posture solution algorithm used in the data solution information processing box.

[0086] Based on this, in this embodiment, the digital information processing module adopts an algorithm for solving the relative posture information of the space target based on the digital simulation image of the space target, wherein the algorithm for solving the relative posture information of the space target based on the digital simulation image of the space target is the same as the algorithm for solving the relative posture information of the space target based on the physical simulation image of the space target.

[0087] This embodiment introduces digital twin technology. The digital simulation test subsystem is a digital twin of the physical simulation test subsystem to ensure the consistency of the physical simulation test and digital simulation test results.

[0088] In the space scene simulation part: the space scene digital simulation module performs geometric structure modeling based on the three-dimensional scanning data of the space target model in the space scene physical simulation module, constructs a digital model of the space target geometric structure, performs optical property measurement modeling based on the surface material of the space target model, constructs a digital model of the optical properties of the space target, performs space lighting modeling based on the solar simulator, and constructs a digital model of space solar lighting. The space scene digital simulation module and the space scene physical simulation module use the same orbital dynamics model to obtain real-time relative posture data of the real space target and the real optical imaging module, and use the relative posture data to drive the space relative motion simulation robot arm and the approximate motion simulation guide rail to perform relative posture simulation of the physical object, and at the same time use the relative posture data to perform digital relative posture simulation.

[0089] In the optical imaging component, the digital optical imaging module utilizes a ray tracing imaging simulation model based on physical effects (i.e., the ray tracing method), ensuring the accuracy of the space target optical transmission simulation calculations. Furthermore, actual performance testing of the optical camera used in the physical optical imaging module, including distortion, noise, and radiation response, was conducted. Based on these test results, the digital optical imaging module was calibrated, incorporating distortion simulation and radiation quantization simulation processes to ensure consistency between the physical and digital simulated images of the space target.

[0090] In the information processing section, the digital information processing module digitally simulates the operating sequence of the data solution information processing box used by the physical information processing module, ensuring that the physical and digital simulations have the same pose data output. Furthermore, the digital and physical information processing modules use the same algorithm for solving the relative pose of spatial targets, ensuring consistency in the pose output results of the physical and digital simulations.

[0091] like Figure 4 As shown in the figure, the data solution information processing box adopts a multi-processor, multi-core embedded hardware architecture. It digitally simulates the algorithm working sequence of the physical embedded system through multi-threading, soft synchronization, shared memory and other methods. The main steps are:

[0092] 1) Each functional execution core of the physical processor is simulated using a separate simulation thread, including image preprocessing thread, feature extraction thread, image unit communication thread, integrated pose solution thread, and integrated unit communication thread.

[0093] 2) After being encapsulated through the data interface, each thread can share the core processing algorithm code with the embedded system. At the same time, through soft synchronization control between threads, the working timing and data update cycle are guaranteed to be compatible with the physical system.

[0094] 3) Data exchange between threads is performed using shared memory, with independent shared memory regions divided according to the physical composition of the system's processing units. The image processing unit shared memory region is responsible for data exchange between image processing unit simulation threads, the integrated processing unit shared memory region is responsible for data exchange between integrated processing unit simulation threads, and the inter-processing unit shared memory region is responsible for data exchange between the integrated processing unit and the image processing unit.

[0095] This embodiment can further realize the flexible combination of multiple working modes. The digital optical imaging module and digital information processing module in the digital simulation test subsystem have the same physical communication interface and communication protocol as the physical optical imaging module and physical information processing module in the physical simulation test subsystem. According to different space target visual navigation system testing requirements, in-situ replacement between modules can be realized, thereby improving the flexibility of use of the digital twin simulation test system of the space target visual navigation system.

[0096] The working modes of the digital twin simulation test system of the space target visual navigation system of this embodiment include:

[0097] (1) Working mode 1: full physical simulation test, used to test the navigation performance of space target visual navigation system in typical test tasks, such as Figure 5 As shown in FIG, the workflow is as follows: the physical optical imaging module performs physical imaging simulation on the space scene physical simulation module to generate a physical simulation image of the space target, and sends the physical simulation image of the space target to the physical information processing module to solve and obtain the relative position information of the space target.

[0098] (2) Working mode 2: Digital imaging object processing simulation test, used to conduct full-scene test mission navigation performance coverage test of space target visual navigation system through real objects, such as Figure 6 As shown in FIG, the workflow is as follows: the digital optical imaging module performs digital imaging simulation on the space scene digital simulation module to generate a digital simulation image of the space target, and sends the digital simulation image of the space target to the physical information processing module to solve and obtain the relative position information of the space target.

[0099] (3) Working mode 3: Physical imaging digital processing simulation test, used to test the navigation performance of typical test tasks without a physical data solution information processing box, such as Figure 7 As shown in FIG, the workflow is as follows: the physical optical imaging module performs physical imaging simulation on the space scene physical simulation module to generate a physical simulation image of the space target, and the physical simulation image of the space target is sent to the digital information processing module to solve and obtain the relative position information of the space target.

[0100] (4) Working mode 4: Full digital simulation test, used to conduct full-scenario test task navigation performance coverage test without a physical data solution information processing box, such as Figure 8 As shown in FIG, the workflow is as follows: the digital optical imaging module performs digital imaging simulation on the space scene digital simulation module to generate a digital simulation image of the space target, and sends the digital simulation image of the space target to the digital information processing module to solve and obtain the relative position information of the space target.

[0101] Based on this, in this embodiment, the physical communication interface and communication protocol of the physical optical imaging module are the same as the physical communication interface and communication protocol of the digital optical imaging module, and the physical communication interface and communication protocol of the physical information processing module are the same as the physical communication interface and communication protocol of the digital information processing module.

[0102] At this time, the working modes of the digital twin simulation test system of the space target visual navigation system include: full physical simulation test, digital imaging physical processing simulation test, physical imaging digital processing simulation test and full digital simulation test.

[0103] When conducting a full physical simulation test, the digital twin simulation test system of the space target visual navigation system includes a space scene physical simulation module, a physical optical imaging module and a physical information processing module connected in sequence.

[0104] When conducting digital imaging physical object processing simulation tests, the digital twin simulation test system of the space target visual navigation system includes a space scene digital simulation module, a digital optical imaging module, and a physical object information processing module connected in sequence.

[0105] When conducting a physical imaging digital processing simulation test, the digital twin simulation test system of the space target visual navigation system includes a space scene physical simulation module, a physical optical imaging module and a digital information processing module connected in sequence.

[0106] When conducting a full digital simulation test, the digital twin simulation test system of the space target visual navigation system includes a space scene digital simulation module, a digital optical imaging module and a digital information processing module connected in sequence.

[0107] In response to the ground simulation test requirements of the space target visual navigation system, this embodiment designs a digital twin simulation test system, which includes a physical simulation test subsystem and a digital simulation test subsystem. The physical simulation test subsystem includes a physical simulation module of the space scene, a physical optical imaging module and a physical information processing module. The digital simulation test subsystem includes a digital simulation module of the space scene, a digital optical imaging module and a digital information processing module. The digital simulation test subsystem is a digital twin of the physical simulation test subsystem. Virtual-real mapping is realized between the corresponding modules of the two subsystems, and can be arbitrarily combined and configured to meet different ground simulation test requirements.

[0108] In response to the shortcomings of the two existing simulation test methods, this embodiment proposes a digital twin simulation test system for a space target visual navigation system. The digital twin modeling technology is used to ensure the consistency of the digital simulation and physical simulation test results. In addition, the virtual and real modules in the digital twin simulation test system have a unified interface design, which can realize flexible in-situ replacement between modules and meet the requirements of various test states. That is, the digital twin simulation test system for the space target visual navigation system of this embodiment achieves a balance between the authenticity and coverage of the ground simulation test of the space target visual navigation system by combining physical simulation and digital simulation. The digital simulation test subsystem constructed by the digital twin method realizes the virtual-real mapping of the physical simulation test subsystem. Compared with the traditional ground physical simulation test method, the test scene coverage is wider, and compared with the traditional digital simulation test method, the simulation authenticity is higher. The virtual and real modules in the digital twin simulation test system of the space target visual navigation system adopt a unified interface design, which can realize the virtual-real in-situ replacement between modules, has strong flexibility, and meets the requirements of various test states.

[0109] 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.

[0110] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may 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 digital twin simulation test system for a space target visual navigation system, characterized in that: The digital twin simulation test system of the space target visual navigation system includes: a physical simulation test subsystem and a digital simulation test subsystem, wherein the physical simulation test subsystem is used to perform physical simulation of the space target visual navigation system, and the digital simulation test subsystem is a digital twin model of the physical simulation test subsystem, and the digital simulation test subsystem is used to perform digital simulation of the space target visual navigation system; The physical simulation test subsystem includes a space scene physical simulation module, a physical optical imaging module, and a physical information processing module; the space scene physical simulation module is used to simulate the on-orbit optical characteristics, on-orbit illumination state, and relative motion state of a real space target through a physical model; the physical optical imaging module is used to image the space target through the physical model to obtain a physical simulation image of the space target, so as to simulate the imaging process of the real optical imaging module; the physical information processing module is used to process the physical simulation image of the space target through the physical model to obtain the relative position and posture of the space target, so as to simulate the processing process of the real information processing module; The digital simulation test subsystem includes a space scene digital simulation module, a digital optical imaging module and a digital information processing module; the space scene digital simulation module is used to simulate the on-orbit optical characteristics, on-orbit illumination state and relative motion state of a real space target through a digital model; the digital optical imaging module is used to image the space target through a digital model to obtain a digital simulation image of the space target, so as to simulate the imaging process of the real optical imaging module; the digital information processing module is used to process the digital simulation image of the space target through a digital model to obtain the relative position and posture of the space target, so as to simulate the processing process of the real information processing module.

2. The digital twin simulation test system of the space target visual navigation system according to claim 1 is characterized in that: The space scene physical simulation module includes a space target model, a solar simulator and a space relative motion simulation manipulator; The geometric structure and surface material of the space target model are identical to those of the real space target, so as to simulate the on-orbit optical characteristics of the real space target; The solar simulator uses a parallel light source with the same spectral characteristics as the sun outside the atmosphere, and its position can be adjusted to simulate the on-orbit illumination state of a real space target; The space target model and the real optical imaging module are both installed on the space relative motion simulation robotic arm; the space relative motion simulation robotic arm is used to adjust the relative posture of the space target model relative to the real optical imaging module to simulate the relative motion state of the real space target.

3. The digital twin simulation test system of the space target visual navigation system according to claim 2 is characterized in that: The space relative motion simulation robotic arm includes a target motion simulation six-degree-of-freedom robotic arm and a measurement system motion simulation six-degree-of-freedom robotic arm. The space target model is installed on the target motion simulation six-degree-of-freedom robotic arm, and the real optical imaging module is installed on the measurement system motion simulation six-degree-of-freedom robotic arm. The target motion simulation six-degree-of-freedom robotic arm is used to adjust the posture of the space target model, and the measurement system motion simulation six-degree-of-freedom robotic arm is used to adjust the posture of the real optical imaging module to adjust the relative posture of the space target model relative to the real optical imaging module, so as to simulate the relative motion state of the real space target.

4. The digital twin simulation test system of the space target visual navigation system according to claim 3 is characterized in that: The space scene physical simulation module also includes an approximate motion simulation guide rail, on which the target motion simulation six-degree-of-freedom robotic arm and the measurement system motion simulation six-degree-of-freedom robotic arm are both installed; the approximate motion simulation guide rail is used to adjust the relative distance between the space target model and the physical optical imaging module to adjust the relative posture of the space target model relative to the physical optical imaging module, so as to simulate the relative motion state of the real space target.

5. The digital twin simulation test system of the space target visual navigation system according to claim 1 is characterized in that: The physical optical imaging module includes several optical cameras; the physical information processing module includes a data solution information processing box, and the data solution information processing box has an algorithm for solving the relative posture information of the space target based on the physical simulation image of the space target.

6. The digital twin simulation test system of the space target visual navigation system according to claim 1 is characterized in that: The space scene digital simulation module includes a digital model of relative motion of space targets, a digital model of geometric structure of space targets, a digital model of optical characteristics of space targets and a digital model of space sunlight; The digital model of relative motion of the space target is used to obtain the simulated position and posture of the real space target, the real optical imaging module and the real sun based on the orbital dynamics model in real time simulation calculation, so as to simulate the relative motion state of the real space target; The digital model of the geometric structure of the space target includes the position and surface material of each triangular facet obtained by meshing the surface of the geometric structure model of the space target based on the simulated position and posture of the real space target; The position includes the three-dimensional coordinates of each vertex of the triangle surface element and the three-dimensional coordinates of the normal vector of the triangle surface element; The digital model of the optical characteristics of the space target is used to measure the reflectance and perform parameterized fitting of the bidirectional reflectance distribution function for each surface material to obtain the optical characteristic model parameters of the surface material, so as to simulate the on-orbit optical characteristics of the real space target; The space solar illumination digital model is used to treat the real sun as an equivalent black body with a temperature of 5900K, calculate the real sun's light source radiation brightness in the visible spectrum using Planck's formula, and determine the direction vector of the sun's rays based on the simulated position of the real space target and the simulated position of the real sun, so as to simulate the on-orbit illumination state of the real space target.

7. The digital twin simulation test system of the space target visual navigation system according to claim 6 is characterized in that: The digital optical imaging module is used to generate a direction vector of the tracking light for each pixel, determine the triangular surface element intersecting with the tracking light of each pixel based on the simulated posture of the real space target, the simulated posture of the real optical imaging module and the digital model of the geometric structure of the space target, determine the radiation brightness of each pixel based on the surface material of the triangular surface element intersecting with the tracking light of each pixel, the digital model of the optical characteristics of the space target and the digital model of space sunlight, obtain a radiation brightness image, and perform distortion simulation processing and radiation quantization simulation processing on the radiation brightness image to obtain a digital simulation image of the space target.

8. The digital twin simulation test system of the space target visual navigation system according to claim 5 is characterized in that: The digital information processing module adopts an algorithm for solving the relative posture information of the space target based on the digital simulation image of the space target; wherein, the algorithm for solving the relative posture information of the space target based on the digital simulation image of the space target is the same as the algorithm for solving the relative posture information of the space target based on the physical simulation image of the space target.

9. The digital twin simulation test system of the space target visual navigation system according to claim 1 is characterized in that: The physical communication interface and communication protocol of the physical optical imaging module are the same as those of the digital optical imaging module, and the physical communication interface and communication protocol of the physical information processing module are the same as those of the digital information processing module.

10. The digital twin simulation test system of the space target visual navigation system according to claim 9, characterized in that: The working modes of the digital twin simulation test system of the space target visual navigation system include: full physical simulation test, digital imaging physical processing simulation test, physical imaging digital processing simulation test and full digital simulation test; When conducting a full-physical simulation test, the digital twin simulation test system of the space target visual navigation system includes a space scene physical simulation module, a physical optical imaging module, and a physical information processing module connected in sequence; When conducting a digital imaging physical object processing simulation test, the digital twin simulation test system of the space target visual navigation system includes a space scene digital simulation module, a digital optical imaging module and a physical object information processing module connected in sequence; When conducting a physical imaging digital processing simulation test, the digital twin simulation test system of the space target visual navigation system includes a space scene physical simulation module, a physical optical imaging module, and a digital information processing module connected in sequence; When conducting a full digital simulation test, the digital twin simulation test system of the space target visual navigation system includes a space scene digital simulation module, a digital optical imaging module and a digital information processing module connected in sequence.

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