A ground-based experimental system for dynamic measurement of the luminosity of space targets

Abstract

The application discloses a kind of space target luminosity dynamic measurement ground test system, the system includes: multiple degrees of freedom controllable rotary table, controllable rotary table is connected with satellite scale model, and controllable rotary table is used to drive satellite scale model multi-angle rotation adjustment;Visible light detection unit is located in the direction of satellite scale model reflected light path, it is used to image satellite scale model and generates continuous observation image sequence;Light source unit, it is used to simulate the parallel light source of sun, and light source is directly on satellite scale model;And general control unit.General control unit is used to control light source intensity, rotary table motion parameter and image acquisition, and image data is reduced sampling processing, generates the luminosity sequence of simulated long-distance observation.The technical scheme provided by the application can provide reliable technical support for space target identification, orbit prediction and stealth technology verification, with innovation, practicality and economy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of space target optical characteristic measurement, and particularly relates to a space target photometric dynamic measurement ground experiment system. BACKGROUND

[0002] In a ground experiment environment, the photometric signal of a space target is usually obtained by building a simulation environment to measure the visible light scattering characteristics of the target. Specifically, a scaled model of the target is placed on an electrically controlled rotating table, parallel light is emitted by a solar simulator, and the parallel light is incident on the surface of the scaled model of the target at a specific angle. Corresponding detection equipment is fixed at a specific position in space, and the optical characteristic data of the overall reflection of the target is received by the detection equipment.

[0003] At present, in order to meet the needs of space target optical characteristic verification, a space target optical characteristic measurement system capable of measuring the scattering characteristics of a target at a specific angle is constructed. However, the current experiment process has limitations, and only the photometric data recorded in a scattered manner can be used to verify the target characteristic model, and it is difficult to quickly verify the target state estimation and other processing algorithms based on photometric data under the dynamic motion condition of the space target. This limits more in-depth and comprehensive research on space targets, and more advanced measurement systems and experiment methods need to be developed to break through the existing bottlenecks and improve the research level of space targets. SUMMARY

[0004] The main purpose of the present application is to provide a space target photometric dynamic measurement ground experiment system, which aims to at least solve the related technical problems mentioned in the related art.

[0005] To achieve the above-mentioned purpose, the present application provides a space target photometric dynamic measurement ground experiment system, which comprises:

[0006] A multi-degree-of-freedom controllable rotating table, a scaled model of a satellite is connected to the controllable rotating table, and the controllable rotating table is used to drive the scaled model of the satellite to rotate at multiple angles for adjustment;

[0007] A visible light detection unit is located in the direction of the reflected light path of the scaled model of the satellite, and is used to image the scaled model of the satellite and generate a continuous observation image sequence;

[0008] A light source unit is used to simulate the parallel light source of the sun, and the light source is directly incident on the scaled model of the satellite; and

[0009] A total control unit is in communication connection with the controllable rotating table, the visible light detection unit and the light source unit;

[0010] The total control unit is used to control the light source intensity, the rotating table motion parameters and the image acquisition, and to perform down-sampling processing on the image data to generate a photometric sequence simulating long-distance observation.

[0011] In an embodiment of the present application, the controllable turntable is a three-degree-of-freedom turntable, comprising:

[0012] an azimuth axis for realizing continuous rotation of 0-360°;

[0013] a pitch axis for realizing angle adjustment of ±45°; and

[0014] a roll axis for realizing angle adjustment of ±180°.

[0015] The repeat positioning accuracy of the controllable turntable is ≤0.005°, and the angular velocity and angular acceleration are supported for programming control.

[0016] In an embodiment of the present application, the controllable turntable comprises:

[0017] a base, wherein an azimuth driving unit is arranged on the base, and a first connecting frame is connected to the azimuth driving unit;

[0018] a roll driving unit connected to the first connecting frame, and a second connecting frame is connected to the roll driving unit; and

[0019] a pitch driving unit connected to the second connecting frame, and a third connecting frame is connected to the pitch driving unit, and the satellite scaled-down model is connected to the third connecting frame.

[0020] The azimuth driving unit, the roll driving unit and the pitch driving unit are respectively in communication connection with the general control unit.

[0021] In an embodiment of the present application, the shape, size and surface material of the satellite scaled-down model maintain geometric similarity with the real space target to be simulated, and the surface material comprises a diffuse reflection coating area and a mirror reflection coating area for simulating the reflection characteristics of different materials.

[0022] In an embodiment of the present application, the visible light detection unit is a visible light camera, comprising:

[0023] an image acquisition unit and a simulation simulation unit.

[0024] The image acquisition unit is used for imaging and shooting the satellite model, and the simulation simulation unit is used for performing down-sampling processing on the image through a target region extraction algorithm to generate simulated observation images of different sizes of targets, so as to equivalent long-distance observation effect.

[0025] In an embodiment of the present application, the light source unit comprises:

[0026] A box body is provided with a light source cavity, a reflector bowl and a xenon lamp light source are installed in the light source cavity, and the xenon lamp light source is located at the focal point of the reflector bowl;

[0027] A reflector is arranged above the reflector bowl at an inclination of 45°, and is used for reflecting the light beam emitted by the xenon lamp light source to the integrating mirror;

[0028] The integrating mirror is arranged on the reflected light path of the reflector, and is used for homogenizing the light beam intensity; and

[0029] The lens group comprises a plurality of lenses, and is used for collimating the light beam into parallel light and irradiating the satellite scale model.

[0030] In an embodiment of the present application, the total control unit comprises:

[0031] The image processing module is used for target region extraction and resolution down-sampling of the extended target image collected by the visible light camera, and generates a simulated observation image of a spot or point target; and

[0032] The photometric calibration module is used for converting the gray value of the target within a limited distance into equivalent remote observation photometric information according to the light source intensity parameter and the atmospheric attenuation model.

[0033] In an embodiment of the present application, the photometric calibration module realizes equivalent simulation of the photometric characteristics of the target under different solar angles by dynamically adjusting the radiation intensity of the xenon lamp light source and combining the bidirectional reflectance distribution function model of the target surface material.

[0034] The present application also provides a space target photometric dynamic measurement method of the system as described above, which comprises:

[0035] S1. The radiation intensity of the simulated light source and the attitude motion parameters of the controllable turntable are set by the total control unit;

[0036] S2. The controllable turntable is controlled to drive the satellite scale model to continuously rotate in three axes, so as to simulate the dynamic attitude change of the target;

[0037] S3. The reflected light image sequence of the satellite scale model is collected by the visible light camera;

[0038] S4. The target region extraction and down-sampling processing of the image sequence are performed by the experimental total control system, so as to generate a photometric curve of equivalent remote observation;

[0039] S5. The photometric curve is input into a non-cooperative target characteristic analysis algorithm, so as to inverse the motion parameters and surface characteristics of the target.

[0040] In an embodiment of the present application, the down-sampling processing in step S4 comprises: performing Gaussian blur and pixel merging operations on the expanded target image, so that the imaging size of the target in the image is less than a preset threshold.

[0041] In summary, the present application provides a ground-based experiment system for dynamic measurement of the luminosity of a space target. The dynamic attitude change of the space target is accurately simulated by a multi-degree-of-freedom controllable turntable, and an experiment condition close to a real scene is provided for luminosity characteristic analysis. Through image down-sampling processing and luminosity calibration algorithms, the experiment data within a limited distance are converted into equivalent long-distance observation results, and the fidelity of a ground-based telescope simulation is significantly improved. The high-parallelism light beam generated by the light source unit simulates the irradiation characteristics of sunlight, and ensures the real reproduction of the reflection characteristics of the target surface. Through ground-based experiments to replace part of the in-orbit measurement, the cost of a space mission is significantly reduced, and uncontrollable factors such as atmospheric turbulence and weather interference in real observation are avoided, which can effectively improve the stability of the experiment data. At the same time, through the normalization gray processing and dynamic light source adjustment technology, the equipment noise and environmental interference can be effectively suppressed, and the demand for high-precision situation awareness is met.

[0042] The high-fidelity simulation and efficient analysis of the dynamic characteristics of the luminosity of the space target can be effectively realized, and reliable technical support is provided for space target recognition, orbit prediction and stealth technology verification, which has innovation, practicality and economy. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0044] Figure 1 A perspective structural schematic view of an embodiment of the space target luminosity dynamic measurement ground experiment system provided by the present application;

[0045] Figure 2 A structural schematic view of the controllable turntable of the space target luminosity dynamic measurement ground experiment system provided by the present application in an embodiment;

[0046] Figure 3 A structural schematic view of the visible light detection unit of the space target luminosity dynamic measurement ground experiment system provided by the present application in an embodiment;

[0047] Figure 4 A module schematic view of the general control unit of the space target luminosity dynamic measurement ground experiment system provided by the present application in an embodiment;

[0048] Figure 5 A flowchart of an embodiment of a space target photometric dynamic measurement method provided by the present application.

[0049] BRIEF DESCRIPTION OF DRAWINGS

[0050] 100, controllable turntable; 110, base; 120, azimuth driving unit; 121, first connecting frame; 130, roll driving unit; 131, second connecting frame; 140, pitch driving unit; 141, third connecting frame;

[0051] 200, satellite scale model;

[0052] 300, visible light detection unit;

[0053] 400, light source unit; 410, box body; 411, light source cavity; 412, reflector bowl; 413, xenon lamp light source; 414, reflector; 415, integrating mirror; 416, lens group;

[0054] 500, total control unit; 510, image processing module; 520, photometric calibration module.

[0055] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0057] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.

[0058] In addition, if the embodiments of the present application involve descriptions of "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features.

[0059] Please refer to Figures 1 to 4The application provides a space target photometric dynamic measurement ground experiment system, which can improve the poor photometric measurement effect of the space target.

[0060] Specifically, the space target photometric dynamic measurement ground experiment system comprises a multi-degree-of-freedom controllable turntable 100, a satellite scaled model 200, a visible light detection unit 300, a light source unit 400 and a general control unit 500. The satellite scaled model 200 is connected to the controllable turntable 100, and the controllable turntable 100 can be used to drive the satellite scaled model 200 to adjust the attitude in space. The light source unit 400 and the visible light detection unit 300 are located at the periphery of the controllable turntable 100, the light source unit 400 can be used to simulate the parallel light source of the sun, and the light source is directly incident on the satellite scaled model 200.

[0061] The visible light detection unit 300 is located in the direction of the reflected light path of the satellite scaled model 200, which is used to image the satellite scaled model 200 and generate a continuous observation image sequence.

[0062] It should be noted that the general control unit 500 is in communication connection with the controllable turntable 100, the visible light detection unit 300 and the light source unit 400, and the general control unit 500 can be used to control the light source intensity, the turntable motion parameters and the image acquisition. The general control unit 500 can perform down-sampling processing on the image data and generate a photometric sequence simulating a long-distance observation.

[0063] In some embodiments, the controllable turntable 100 is a three-degree-of-freedom turntable.

[0064] Specifically, the controllable turntable 100 comprises at least an azimuth axis, a pitch axis and a roll axis. The azimuth axis is used to realize the continuous rotation of the satellite scaled model 200 by 0-360°, the pitch axis is used to realize the angle adjustment by ±45°, and the roll axis is used to realize the angle adjustment by ±180°.

[0065] It should be noted that the repeat positioning accuracy of the controllable turntable 100 is ≤0.005°, and the programmed control of the angular velocity and the angular acceleration is supported.

[0066] Further, the controllable turntable 100 further comprises a base 110, an azimuth driving unit 120, a roll driving unit 130 and a pitch driving unit 140. The base 110 is a fixed support part of the turntable, which is installed on an experiment platform to ensure the stability of the overall structure. The azimuth driving unit 120 is installed on the base 110 and is used to drive a first connecting frame 121 to rotate around the azimuth axis, and the rotation range is 0-360°. The first connecting frame 121 connects the azimuth driving unit 120 and the roll driving unit 130, and is used to transmit the motion of the azimuth axis.

[0067] Further, the roll driving unit 130 is mounted on the first connecting frame 121, for driving the second connecting frame 131 to rotate around the roll axis, with a rotation range of ±180°. The second connecting frame 131 connects the roll driving unit 130 and the pitch driving unit 140, for transmitting the motion of the roll axis.

[0068] The pitch driving unit 140 is mounted on the second connecting frame 131, for driving the third connecting frame 141 to rotate around the pitch axis, with a rotation range of ±45°. The third connecting frame 141 connects the pitch driving unit 140 and the satellite scale model 200, for transmitting the motion of the pitch axis.

[0069] It is foreseeable that the satellite scale model 200 is fixed on the third connecting frame 141, for simulating the luminosity characteristics of the real space target.

[0070] It is noted that in some embodiments, the driving of the azimuth driving unit 120 employs a high-precision stepper motor, equipped with an encoder feedback system, to ensure that the rotation accuracy of the azimuth axis is ≤0.005°. The motor is connected to the first connecting frame 121 through a speed reducer, supporting continuous rotation and fixed-point positioning functions.

[0071] The roll driving unit 130 employs a servo motor for driving, and is equipped with a torque sensor to ensure smooth motion of the roll axis within the range of ±180°. The motor is connected to the second connecting frame 131 through a shaft coupling, supporting accurate control of angular velocity and angular acceleration. The pitch driving unit 140 employs a direct-current brushless motor, equipped with a high-resolution encoder to ensure accurate positioning of the pitch axis within the range of ±45°. The motor is connected to the third connecting frame 141 through a gear box, supporting fast response and high stability. The total control unit 500 can be connected to the azimuth driving unit 120, the roll driving unit 130 and the pitch driving unit 140 through the RS-485 communication protocol, to send control instructions and receive feedback data in real time.

[0072] In some embodiments, the design and manufacture of the satellite scale model 200 strictly follow the principle of geometric similarity, with its shape, size and surface material consistent with the real space target to be simulated.

[0073] For example, if the target is a cubic satellite with a size of 2m x 2m x 2m, the scale model is reduced to 0.2m x 0.2m x 0.2m at a scale of 1:10. The surface material of the model is specially treated, divided into diffuse reflection coating areas and mirror reflection coating areas, to simulate the reflection characteristics of different parts of the real satellite.

[0074] The diffuse reflection coating region adopts high reflectivity white paint (such as Spectra lon material), and its bidirectional reflectance distribution function (BRDF) is close to the Lambertian characteristic, which is used to simulate the scattered reflection of a solar panel or a satellite body. The specular reflection coating region adopts high light aluminum film or silver-plated material, and its BRDF exhibits strong specular reflection characteristics, which is used to simulate the specular reflection effect of a satellite antenna or a metal shell. Through this design, the scale model can accurately reproduce the photometric characteristics of the real space target under different lighting conditions, and provide high-fidelity simulation data for ground experiments. Based on this, the parallel light beam generated by the light source unit 400 irradiates the scale model surface, and the visible light detection unit 300 collects the reflected light image sequence, and the photometric calibration and data analysis are performed through the general control unit 500, and finally the photometric curve of equivalent long-distance observation is generated, which is used to verify the performance of the space target recognition and situation awareness algorithm.

[0075] In some embodiments, the visible light detection unit 300 adopts a high-resolution visible light camera, and the core functions thereof are realized by the image acquisition unit and the simulation simulation unit.

[0076] Specifically, the image acquisition unit is equipped with a high-sensitivity CMOS sensor and an adjustable focus optical lens, which is used to image and shoot the satellite scale model 200 at a high frame rate, and capture the reflected light image sequence of the target in a dynamic motion state. The simulation simulation unit is integrated in the camera, and the original image is processed through a target region extraction algorithm. First, the target region of the satellite scale model 200 is identified and extracted, and then the image is down-sampled by using the Gaussian blur and pixel merging technology, and the simulated observation image of the target of different sizes is generated.

[0077] For example, the target region of 100x100 pixels in the original image is down-sampled to a 10x10 pixel spot target, or further down-sampled to a single-pixel point target, to equivalently simulate the imaging effect of the ground-based telescope under the long-distance observation condition. Through this processing mode, the visible light detection unit 300 can simulate the observation characteristics of the target at different distances, and provide high-fidelity experimental data for space target recognition and photometric characteristic analysis. Based on this, the general control unit 500 can receive and process the simulated observation image generated by the visible light detection unit 300 in real time, and generate the photometric sequence of equivalent long-distance observation by combining the algorithm of the photometric calibration module 520, which is used to verify the performance of the space situation awareness algorithm.

[0078] In some embodiments, the light source unit 400 is used to generate a light beam with high parallelism to simulate the illumination condition of the sun. The core components of the light source unit 400 include a box 410, a reflector bowl 412, a xenon lamp light source 413, a reflector 414, an integrating mirror 415, and a lens group 416.

[0079] The light source cavity 411 is internally provided with a parabolic reflector 412, and the xenon lamp light source 413 is accurately installed at the focal point of the reflector 412 to ensure that the light rays form a parallel light beam after reflection. The reflector 414 is arranged at an angle of 45° above the reflector 412 to reflect the light beam emitted by the xenon lamp light source 413 to the integrating mirror 415. The integrating mirror 415 adopts a microlens array design to homogenize the light beam intensity distribution and eliminate hot spot effects. The lens group 416 is composed of multiple achromatic lenses to further collimate the light beam and adjust the spot size, and finally generate a high-parallelism light beam to irradiate the satellite scale model 200.

[0080] It can be understood that the light source unit 400 can accurately simulate the irradiation conditions of the sun in the experimental environment, and provide a high-stability and high-uniformity light environment for the dynamic measurement of the luminosity of the space target. In the experiment, the total control unit 500 dynamically controls the output power of the light source by adjusting the current intensity of the xenon lamp light source 413 to meet the needs of different experimental scenarios.

[0081] In some embodiments, the total control unit 500 cooperates with the image processing module 510 and the luminosity calibration module 520 to realize real-time processing and calibration of the dynamic measurement data of the luminosity of the space target.

[0082] The image processing module 510 receives the extended target image (for example, a 1000x1000 pixel original image) collected by the visible light detection unit 300.

[0083] First, the reflected light region of the satellite scale model 200 is identified and cropped using a target region extraction algorithm (such as ROI segmentation based on edge detection).

[0084] Subsequently, the original high-resolution image is down-sampled into a spot target (such as 50x50 pixels) or a point target (single pixel) by using Gaussian blur (kernel size of 5x5 pixels) and pixel merging technology (such as merging a 10x10 pixel region into one pixel), to simulate the imaging characteristics of a ground-based telescope in long-distance observation.

[0085] The luminosity calibration module 520 can convert the down-sampled image gray value into equivalent long-distance observation luminosity information according to the real-time radiation intensity parameters of the light source unit 400, such as the irradiance corresponding to the current value of the xenon lamp light source 413, the bidirectional reflectance distribution function (BRDF) model of the target surface material, and the preset atmospheric attenuation coefficient.

[0086] Specifically, the dynamic light source adjustment can allow the current intensity of the xenon lamp light source 413 to be adjusted by the total control unit 500 according to the target attitude (such as the solar angle θ = 30°). The output irradiance satisfies the formula:

[0087] I ground = I space • cos(θ) • e -α•d

[0088] where I 空间 is the theoretical irradiance of the space target.

[0089] The BRDF data of the surface material of the satellite scale model 200 can be combined to calculate the reflected radiation intensity of the target under a specific observation geometry. By geometric attenuation correction and atmospheric transmission model, the limited distance photometric data of the ground experiment is converted into equivalent long-distance observation values to generate a continuous photometric curve.

[0090] Specifically, in the actual processing process, the following steps can be included.

[0091] First, the image gray value is normalized.

[0092] Through the formula: I norm (x,y) is obtained.

[0093] where I max and I min are the minimum and maximum gray values of the image, respectively. Based on the above method, through the formula, the gray values of all pixels are linearly mapped to the range [0, 1].

[0094] For example, I norm (x,y) = 0 corresponds to the darkest pixel of the original image; I norm (x,y) = 1 corresponds to the brightest pixel of the original image.

[0095] Since the response characteristics of different cameras or light sources can cause differences in original gray values, normalization can unify the dimensions, facilitating cross-device data comparison. In addition, normalized data is easier to combine with physical models (such as BRDF, radiation transfer equation), improving computational efficiency.

[0096] Convert the gray value to the radiation intensity.

[0097] The reflected radiation intensity I 反射 of the target surface can be calculated according to the light source intensity I 光源 and the BRDF model.

[0098] Through the formula: I 反射 (x,y) = I 光源 • BRDF(θ i ,θ r ,φ) • cos(θ i );

[0099] where θ i is the incident angle, θ r is the reflection angle, and φ is the azimuth angle.

[0100] Furthermore, according to the light source-target distance d 光源 and the target-camera distance d 相机 , the geometric attenuation factor I 几何 (x, y) is calculated.

[0101] Through the formula:

[0102] Furthermore, according to the atmospheric attenuation coefficient a and the equivalent atmospheric path length d 大气 , the atmospheric attenuation factor I 大气 (x, y) is calculated.

[0103] Through the formula:

[0104] Finally, the equivalent long-distance luminosity I 等效 (x, y) is obtained.

[0105] Through the formula:

[0106] Where d 实际 is the size of the real target, and d 缩比 is the size of the scaled model.

[0107] Finally, the above steps are repeated for each frame of image to generate a continuous luminosity sequence {I 等效 (t)} for subsequent spatial target characteristic analysis.

[0108] It should be noted that in the actual experiment, the total control unit 500 can control the controllable turntable 100 to drive the satellite scaled model 200 to roll at an angular velocity of 10° / s, while dynamically adjusting the radiation intensity of the xenon lamp light source 413. The average deviation of the finally generated luminosity sequence and the ground-based telescope measured data is compared, and it is judged whether the deviation comparison value is less than a preset value, so as to verify the simulation accuracy and algorithm reliability of the system.

[0109] Referring to Figure 5 , the application further provides a space target luminosity dynamic measurement method applied to the space target luminosity dynamic measurement ground experiment system.

[0110] The method at least includes the following steps.

[0111] S1. The radiation intensity of the simulation light source and the attitude motion parameters of the controllable turntable 100 are set through the total control unit 500.

[0112] The operator sets the radiation intensity of the light source unit 400 (such as the output of the xenon lamp light source 413 is 50 kW / m 2) and three-axis motion parameters of the controllable turntable 100 (azimuth axis angular velocity 10° / s, pitch axis swing range ±45°, roll axis reciprocating angular velocity 5° / s)

[0113] S2. Control the controllable turntable 100 to drive the satellite scale model 200 to continuously rotate in three axes to simulate the dynamic attitude change of the target. The controllable turntable 100 drives the satellite scale model 200 to continuously rotate in three axes to simulate the dynamic attitude change of the target, such as rolling and spinning in orbit, while the light source unit 400 generates parallel light beams to irradiate the model surface.

[0114] S3. Use the visible light camera to collect a sequence of reflected light images of the satellite scale model 200. For example, the visible light detection unit 300 collects a sequence of reflected light images at a frame rate of 100 fps, and the original image resolution is set to 4096x4096 pixels, covering the full attitude period of the target.

[0115] S4. The experimental total control system extracts the target area and performs down-sampling processing on the image sequence to generate a photometric curve equivalent to long-distance observation.

[0116] In step S4, it includes:

[0117] S401, target area extraction.

[0118] The image processing module 510 uses the Canny edge detection algorithm to locate the contour of the satellite scale model 200 and crops out the target area (such as 1024x1024 pixels).

[0119] S402, down-sampling processing.

[0120] The target area is subjected to Gaussian blur (σ=2.0) and 4x4 pixel merging to generate a 256x256 pixel spot target image, or further down-sampling to a single-pixel target.

[0121] S403, photometric curve generation.

[0122] The photometric calibration module 520 converts the gray value into an equivalent long-distance photometric value in combination with the light source intensity, BRDF model and atmospheric attenuation parameters to generate a photometric curve with a time resolution of 10 ms.

[0123] S5. Input the photometric curve into the non-cooperative target characteristic analysis algorithm to inverse the motion parameters and surface characteristics of the target.

[0124] In step S5, it includes:

[0125] S501, motion parameter extraction.

[0126] The photometric curve is subjected to Fourier transform, a peak frequency (such as 2Hz) is extracted as a target spin frequency, and a posture angle change is calculated through phase analysis.

[0127] S502, surface characteristic recognition.

[0128] Based on the matching of the photometric curve and the BRDF database, the target surface material type is determined (such as identifying that the diffuse reflection area accounts for 60%, and the specular reflection area accounts for 40%).

[0129] In summary, the application provides a space target photometric dynamic measurement ground experiment system, which can accurately simulate the dynamic attitude change of the space target through the multi-degree-of-freedom controllable turntable 100, and provide an experimental condition close to the real scene for photometric characteristic analysis. Through image down-sampling processing and photometric calibration algorithm, the experimental data within a limited distance are converted into equivalent long-distance observation results, which significantly improves the fidelity of the ground-based telescope simulation. The high parallelism light beam generated by the light source unit 400 simulates the irradiation characteristics of sunlight, ensuring the real reproduction of the target surface reflection characteristics. Through ground experiment instead of part of in-orbit measurement, the space mission cost is significantly reduced, while avoiding uncontrollable factors such as atmospheric turbulence and weather interference in real observation, which can effectively improve the stability of experimental data. At the same time, through the normalization gray processing and dynamic light source adjustment technology, the equipment noise and environmental interference can be effectively suppressed, and the high-precision situation awareness demand can be met.

[0130] The space target photometric dynamic characteristics can be effectively simulated and analyzed with high fidelity, which provides reliable technical support for space target recognition, orbit prediction and stealth technology verification, and has innovation, practicality and economy.

[0131] The above description is only an exemplary embodiment of the application, and does not limit the patent scope of the application, and any equivalent structural transformation made by using the content of the application specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the application.

Claims

1. A ground-based experimental system for dynamic photometric measurement of space targets, characterized in that, include: A multi-degree-of-freedom controllable turntable (100) is provided, on which a satellite scale model (200) is connected. The controllable turntable (100) is used to drive the satellite scale model (200) to rotate and adjust at multiple angles. The controllable turntable (100) is a three-degree-of-freedom turntable, including: an azimuth axis for continuous rotation from 0 to 360°; a pitch axis for angle adjustment of ±45°; and a roll axis for angle adjustment of ±180°; wherein, the repeatability of the controllable turntable (100) is ≤0.005°, and it supports programmable control of angular velocity and angular acceleration; The visible light detection unit (300) is located in the reflected light path direction of the satellite scale model (200), and is used to image the satellite scale model (200) and generate a continuous observation image sequence; A light source unit (400) is used to simulate a parallel light source of the sun, and the light source is directly incident on the satellite scale model (200); the light source unit (400) includes: The housing (410) contains a light source cavity (411), and a reflector bowl (412) and a xenon lamp light source (413) are installed inside the light source cavity (411). The xenon lamp light source (413) is located at the focal point of the reflector bowl (412). A reflector (414) is positioned at a 45° angle above the reflector bowl (412) to reflect the light beam emitted by the xenon lamp source (413) to the integrating mirror (415). An integrating mirror (415) is disposed on the reflected light path of the reflector (414) to homogenize the beam intensity; and Lens assembly (416), comprising multiple lenses, for collimating the light beam into parallel light and illuminating the satellite scale model (200); and The main control unit (500) is communicatively connected to the controllable turntable (100), the visible light detection unit (300), and the light source unit (400); The central control unit (500) is used to control the light source intensity, turntable motion parameters and image acquisition, and to perform downsampling processing on the image data to generate a photometric sequence simulating long-distance observation.

2. The ground-based experimental system for dynamic photometric measurement of space targets according to claim 1, characterized in that, The controllable turntable (100) includes: A base (110) is provided on the base (110), and a first connecting frame (121) is connected to the azimuth driving unit (120). A roll drive unit (130) is connected to the first connecting frame (121), and a second connecting frame (131) is connected to the roll drive unit (130); and A pitch drive unit (140) is connected to the second connecting frame (131), and a third connecting frame (141) is connected to the pitch drive unit (140). The satellite scale model (200) is connected to the third connecting frame (141). The azimuth drive unit (120), roll drive unit (130) and pitch drive unit (140) are respectively communicatively connected to the main control unit (500).

3. The ground-based experimental system for dynamic photometric measurement of space targets according to claim 1, characterized in that, The shape, size and surface material of the satellite scale model (200) are geometrically similar to the real space target to be simulated, and the surface material includes a diffuse reflection coating area and a specular reflection coating area to simulate the reflection characteristics of different materials.

4. The ground-based experimental system for dynamic photometric measurement of space targets according to claim 1, characterized in that, The visible light detection unit (300) is a visible light camera, which includes: Image acquisition unit and simulation unit; The image acquisition unit is used to image and capture satellite models, and the simulation unit is used to downsample the images using a target region extraction algorithm to generate simulated observation images of targets of different sizes, so as to achieve an equivalent long-distance observation effect.

5. The ground-based experimental system for dynamic photometric measurement of space targets according to claim 1, characterized in that, The main control unit (500) includes: Image processing module (510) is used to extract target regions and downsample resolution in extended target images acquired by a visible light camera to generate simulated observation images of spotted or point-like targets; and The photometric calibration module (520) is used to convert the gray value of a target within a finite distance into equivalent long-distance observation photometric information based on the light source intensity parameters and the atmospheric attenuation model.

6. The ground-based experimental system for dynamic photometric measurement of space targets according to claim 5, characterized in that, The photometric calibration module (520) dynamically adjusts the radiation intensity of the xenon lamp source (413) and combines it with the bidirectional reflection distribution function model of the target surface material to achieve equivalent simulation of the photometric characteristics of the target under different solar phase angles.

7. A method for dynamically measuring the photometric properties of a space target applied to a ground-based experimental system for dynamically measuring the photometric properties of a space target according to any one of claims 1 to 6, characterized in that, include: S1. The radiation intensity of the simulated light source and the attitude motion parameters of the controllable turntable (100) are set by the main control unit (500); S2. Control the controllable turntable (100) to drive the satellite scale model (200) to rotate continuously on three axes to simulate the dynamic attitude change of the target; S3. Acquire a sequence of reflected light images of a scaled-down satellite model (200) using a visible light camera; S4. The image sequence is extracted and downsampled using the experimental control system to generate an equivalent long-distance observation photometric curve. S5. Input the photometric curve into the non-cooperative target characteristic analysis algorithm to invert the target's motion parameters and surface characteristics.

8. The method for dynamic photometric measurement of a space target according to claim 7, characterized in that, The downsampling process in step S4 includes: Gaussian blur and pixel merging operations are performed on the expanded target image to make the target's imaging size in the image smaller than a preset threshold.

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