Digital twinborn simulation test system of space target visual navigation system

Abstract

The invention discloses a digital twinborn simulation test system of a space target visual navigation system, which relates to the technical field of ground simulation test and comprises a physical simulation test subsystem and a digital simulation test subsystem. The physical simulation test subsystem comprises a space scene physical simulation module, a physical optical imaging module and a physical information processing module, and the digital simulation test subsystem comprises a space scene digital simulation module, a digital optical imaging module and a digital information processing module. The space scene real object simulation module and the space scene digital simulation module are used for simulating the on-orbit optical characteristics, the on-orbit illumination state and the relative motion state of a real space target, and the real object optical imaging module and the digital optical imaging module are used for simulating the imaging process of the real optical imaging module. The physical information processing module and the digital information processing module are used for simulating the processing process of the real information processing module. According to the invention, the ground simulation test can be better carried out on the 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 in the measurement image and further solving the navigation parameters such as the relative position and posture of the space target.

[0003] During the development and on-orbit operation of the space target visual navigation system, it is necessary to use ground simulation test methods to comprehensively test and verify the detection capability, algorithm solution accuracy, and navigation measurement stability of the space target visual navigation system to ensure the smooth execution of on-orbit missions. At present, the main ground simulation test methods include physical simulation test methods and digital simulation test methods. The physical simulation test method requires the construction of a scaled 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 effect is basically consistent with the actual on-orbit situation, but it is greatly restricted by conditions such as site and cost, and can usually only be used for typical key mission tests. The digital simulation test method digitally simulates the imaging and navigation information solution process of the space target through digital scene design modeling. It has the advantages of low test cost and the ability to cover all scene mission conditions. However, there is still a large gap between the digital simulation test effect and the physical simulation test effect, and it cannot fully reflect the impact of the complex space environment on the image texture and posture solution accuracy of the space target.

[0004] Based on this, there is an urgent need for a system that can better perform ground simulation tests on 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 on 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 on 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 a 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 a 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 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 completely 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 the 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 mechanical arm; the space relative motion simulation mechanical arm is used to adjust the relative posture of the space target model with respect 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 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 rail; the approximate motion simulation 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 a plurality of 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 real-time simulation calculation of the orbital dynamics model, 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 face element 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 triangular face element and the three-dimensional coordinates of the normal vector of the triangular face element;

[0020] The digital model of the optical characteristics of the space target is used to measure the reflection coefficient and perform parameterized fitting of the bidirectional reflectance distribution function on 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 regard the real sun as an equivalent black body with a temperature of 5900K, calculate the light source radiation brightness of the real sun in the visible spectrum by Planck's formula, and determine the direction vector of the sun's rays based on the simulated posture of the real space target and the simulated posture 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 of each pixel, determine the triangular face 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 face element intersecting 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 which are 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 of 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 illumination 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 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. The present application achieves a balance between authenticity and coverage of ground simulation tests on space target visual navigation systems by combining physical simulation and digital simulation. The digital simulation test subsystem constructed through digital twinning 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 on space target visual navigation systems can be better performed. 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 drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative 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 schematic diagram of the structure of the space scene physical simulation module provided in Example 1 of the present application.

[0035] Figure 3 A flowchart of the relative position and posture solution algorithm for a space target provided in Example 1 of the present application.

[0036] Figure 4 A schematic diagram of a 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 A schematic diagram of the workflow of the full physical simulation test provided in Example 1 of the present application.

[0038] Figure 6 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 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 A 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 the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[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 working in orbit, the optical imaging module performs optical imaging of the space target outside the navigation space target to obtain the space target image. The information processing module further solves the relative position and posture information of the space target relative to the navigation space target by extracting features from the space target image. The position and posture information includes position information and attitude information. The measured relative position and posture 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 the 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. 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 the physical simulation test of the typical space target visual navigation task that is close to the real on-orbit state. The digital simulation test subsystem can supplement the on-orbit task conditions that the physical simulation test subsystem cannot cover now 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 more 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 geometric structure of the real space target, and the surface uses the same surface material (also called surface material, such as thermal control material) as the real space target to simulate the optical reflection characteristics of the real space target. Based on this, the geometric structure and surface material of the space target model are exactly the same as those of the real space target to simulate the on-orbit optical characteristics 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 truly 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 real 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 with respect to the real optical imaging module to simulate the relative motion state of the real space target.

[0052] Specifically, 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, 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 robotic arms, so as 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.

[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 adjustment 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 rail, which is a rail used to control 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 rail. The approach motion simulation 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, so as 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 the 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 a plurality of 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 relative position solution algorithm of the space target. Figure 3 As shown, the steps of the space target relative posture 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 feature components from the image obtained after image preprocessing, specifically extract the space target docking ring and other feature components in the image through operations such as threshold segmentation, contour extraction, and feature shape screening, and calculate the feature parameters such as the center and axis length of the space target docking ring and other feature components. It should be noted that when the shape of the feature component is a circle, the axis length is the diameter, and when the shape of the feature component is an ellipse, the axis length is the major axis length and the minor axis length.

[0063] 3) Through cross-validation of feature parameters extracted from the simulated images of real space targets taken by multiple optical cameras, correct feature recognition is achieved. Then, the feature parameters corresponding to each optical camera are used as input, and the relative position and posture of the space target is solved through multi-eye vision measurement method. The effectiveness of the solution is evaluated and the relative position and posture 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 relative posture solution algorithm of the space target).

[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 constructs a digital model of the relative motion of space targets to simulate the relative posture data of real space targets and real optical imaging modules in real time. 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 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.

[0070] The relative position and posture data of the real space target and the real optical imaging module are simulated and calculated through the orbital dynamics model. Specifically, by setting the six orbital numbers of the real space target and the motion state equation of the real optical imaging module relative to the real space target, combined with the simulation time and simulation frequency set by 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 relative motion of space targets 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.

[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 by 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, and the triangular facets are classified and labeled according to the surface material type, that is, the 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, and 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 by 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 BRDF to obtain the optical characteristics model parameters of different surface materials, and annotate them 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 at different angles is measured. The different angles include the azimuth and elevation angles of the incident angle of the sun's rays and the azimuth and elevation angles of the outgoing angle of the sun's rays. The final optical characteristics model parameters are the model parameters of the model obtained by fitting different angles and reflection coefficients. Through this optical characteristics 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 of each surface material and perform parameterized fitting of the bidirectional reflectance distribution function to obtain the optical characteristics 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 sunlight illumination is defined by the characteristics of parallel light sources. Specifically, the real sun is regarded as an equivalent black body with a temperature of 5900K, and the Planck formula is used to calculate the radiation brightness of the light source in the visible spectrum. The three-dimensional direction vector of the real sun's light is calculated based on the spatial position of the real sun in the simulated posture and the spatial position of the real space target in the simulated posture. Based on this, the digital model of space sunlight illumination is used to regard the real sun as an equivalent black body with a temperature of 5900K, and calculate the radiation brightness of the light source in the visible spectrum by Planck's formula, and determine the direction vector of the sun's light based on the simulated posture of the real space target and the simulated posture of the real sun, so as 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 the optical camera, receive the digital model data of the above-mentioned space scene digital simulation module, use the ray tracing method to perform digital imaging simulation calculation of the space target, and obtain the digital simulation image of the space target. The specific process is as follows:

[0077] 1) Generate the tracking ray for each pixel according to the geometric imaging model of the optical camera, and calculate the intersection point and corresponding triangular face element of the tracking ray with the real space target according to the relative position and posture of the digital model of the geometric structure of the space target, the real space target and the real optical imaging module.

[0078] 2) According to the surface material of the triangular face element corresponding to the intersection point, the corresponding optical characteristic model parameters are called, and the radiation brightness of the tracking light is calculated in combination with the space sunlight digital model. Specifically, the reflection coefficient is calculated based on the optical characteristic model parameters, and then the product of the radiation brightness of the sun's light source and the reflection coefficient is calculated to obtain the radiation brightness. Repeat this process to calculate the radiation brightness of each pixel and obtain a radiation brightness 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 the distortion simulation, the distortion simulation model parameters include the focal length, principal point position, distortion coefficient, etc. of the optical camera, and the parameters are corrected through the camera parameter calibration test. The optical camera images the known geometric size checkerboard calibration plate in different positions and postures to obtain the calibration image, extract and identify the checkerboard corner points in the calibration image, and use the theoretical parameters of the optical camera as the initial value. The extracted corner point information is brought into the calibration model for iterative optimization, and the actual distortion simulation model parameters of the optical camera can be calculated to ensure that the distortion effect of the digital simulation image of the space target is consistent with the distortion effect of the physical simulation image of the space target.

[0081] In the radiation quantization simulation, the noise simulation model parameters include the noise mean and standard deviation, and the radiation response quantization model parameters are the grayscale quantization coefficients. These parameters are calibrated through the camera radiation calibration test. The optical camera measures and images the uniform surface element of the integrating sphere, adjusts the outgoing radiation brightness of the integrating sphere, and obtains different measurement images. Through the statistical analysis of the mean and standard deviation distribution of the measured image pixel grayscale values ​​under different integrating sphere outgoing radiation brightness, the simulation model parameters such as the noise mean, standard deviation and grayscale quantization coefficient can be calculated to ensure that the noise and radiation response effects of the digital simulation image of the space target are consistent with those of the physical simulation image of the space target.

[0082] Based on this, in this embodiment, the digital optical imaging module is used to generate a 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 face 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 face 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 to obtain a radiation brightness image, 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 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.

[0085] The digital information processing module is used for the image processing process of the digitized simulation data solution information processing box. It receives the digital simulation image of the space target and solves the relative pose information of the space target through the space target relative pose solution algorithm. The solution process of the space target relative pose solution algorithm at this time is completely consistent with the solution process of the space target relative pose solution algorithm used by 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's geometric structure, performs optical property measurement modeling based on the surface material of the space target model, constructs a digital model of the space target's optical properties, performs space illumination modeling based on the solar simulator, and constructs a digital model of space sunlight illumination. The space scene digital simulation module and the space scene physical simulation module use the same orbital dynamics model to obtain real-time relative pose data of real space targets and real optical imaging modules, and use the relative pose data to drive the space relative motion simulation robot and the approximate motion simulation guide rail to perform relative pose simulation of the physical object, and at the same time use the relative pose data to perform digital relative pose simulation.

[0089] In the optical imaging part: the digital optical imaging module adopts a ray tracing imaging simulation model based on physical effects (i.e., ray tracing method) to ensure the accuracy of the optical transmission simulation calculation of the space target. In addition, the imaging characteristics of the distortion, noise, and radiation response of the optical camera used in the physical optical imaging module are actually tested for performance, and the digital optical imaging module is corrected based on the test results, that is, the distortion simulation processing and radiation quantization simulation processing are introduced to ensure the consistency of the physical simulation image of the space target and the digital simulation image of the space target.

[0090] In the information processing part: the digital information processing module digitally simulates the working sequence of the data solution information processing box used by the physical information processing module to ensure that the physical simulation and the digital simulation have the same posture data output effect. In addition, the digital information processing module and the physical information processing module use the same space target relative posture solution algorithm to ensure the consistency of the posture output results of the physical simulation and the digital simulation.

[0091] like Figure 4 As shown in the figure, the data solution information processing box adopts a multi-processor, multi-core embedded hardware architecture, and 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 each thread is encapsulated through the data interface, it can share the core processing algorithm code with the embedded system. At the same time, through soft synchronization control between threads, it can ensure that the working timing and data update cycle are compatible with the physical system.

[0094] 3) The data interaction between each thread adopts the shared memory method, and the independent shared memory area is divided according to the physical composition of the system's processing unit. The image processing unit shared memory area is responsible for the data interaction between the image processing unit simulation threads, the integrated processing unit shared memory area is responsible for the data interaction between the integrated processing unit simulation threads, and the inter-processing unit shared memory area is responsible for the data interaction between the integrated processing unit and the image processing unit.

[0095] This embodiment can further realize 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 testing requirements of the space target visual navigation system, in-situ replacement between modules can be realized, thereby improving the use flexibility 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 the space target visual navigation system through physical objects in typical test tasks, such as Figure 5 As shown, the workflow is: 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 posture information of the space target.

[0098] (2) Working mode 2: Digital imaging object processing simulation test, used to test the navigation performance coverage of the space target visual navigation system in full-scene test tasks through real objects, such as Figure 6 As shown, the workflow is: 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 posture 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, the workflow is: 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 posture 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, the workflow is: 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 which are connected in sequence.

[0104] When conducting digital imaging physical object processing simulation experiments, the digital twin simulation experiment 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 which are 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 which are connected in sequence.

[0106] When conducting a fully 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 which are 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 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 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 view of 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, which ensures the consistency of the digital simulation and physical simulation test effects through digital twin modeling technology, and each virtual and real module in the digital twin simulation test system has 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 the 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 digital twin simulation test system for the space target visual navigation system adopts 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 article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A 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 comprises: a physical simulation test subsystem and a digital simulation test subsystem, wherein the physical simulation test subsystem is used to perform physical simulation on 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 on 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 a 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 a 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 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 mechanical arm; The geometric structure and surface material of the space target model are completely 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 the 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 mechanical arm; the space relative motion simulation mechanical arm is used to adjust the relative posture of the space target model with respect 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 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 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 a plurality of optical cameras; the physical information processing module includes a data solving information processing box, and the data solving information processing box has an algorithm for solving the relative position 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 sunlight in space; 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 real-time simulation calculation of the orbital dynamics model, 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 face element 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 surface element and the three-dimensional coordinates of the normal vector of the triangular surface element; The digital model of the optical characteristics of the space target is used to measure the reflection coefficient and perform parameterized fitting of the bidirectional reflectance distribution function on 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 regard the real sun as an equivalent black body with a temperature of 5900K, calculate the light source radiation brightness of the real sun in the visible spectrum by Planck's formula, and determine the direction vector of the sun's rays based on the simulated posture of the real space target and the simulated posture 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 of 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, perform distortion simulation processing and radiation quantization simulation processing on the radiation brightness image, and 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, 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, 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 which are connected in sequence.

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