Ground experiment system for dynamically measuring luminosity of space target

Abstract

The invention discloses a space target luminosity dynamic measurement ground experiment system, and the system comprises a multi-degree-of-freedom controllable rotary table which is connected with a satellite scaling model and is used for driving the satellite scaling model to rotate and adjust at multiple angles; the visible light detection unit is positioned in the reflection light path direction of the satellite scaling model and is used for imaging the satellite scaling model and generating a continuous observation image sequence; the light source unit is used for simulating a parallel light source of the sun, and the light source directly irradiates the satellite scaling model; and a master control unit. And the master control unit is used for controlling the intensity of the light source, the motion parameters of the rotary table and image acquisition, and carrying out downsampling processing on image data to generate a luminosity sequence for simulating long-distance observation. The technical scheme provided by the invention can provide reliable technical support for space target identification, orbit prediction and stealth technical verification, and has innovativeness, practicability and economical efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring the optical characteristics of space targets, and particularly to a ground experimental system for dynamically measuring the photometric characteristics of space targets. Background Art

[0002] To obtain the photometric signal of a space target in a ground experimental environment, it is usually necessary to build a simulation environment to measure the visible light scattering characteristics of the target. The specific operation is to place the scaled-down model of the target on an electrically controlled rotating table, and use a solar simulator to emit parallel light, so that it is incident on the surface of the scaled-down model of the target at a specific angle. Fix the corresponding detection equipment at a specific position in space to receive the optical characteristic data reflected by the whole target.

[0003] At present, to meet the requirements of verifying the optical characteristics of space targets, a measurement system for the optical characteristics of space targets that can measure the scattering characteristics of targets at specific angles has been constructed. However, there are limitations in the current experimental process. Only the photometric data recorded separately can be used to verify the target characteristic model, and it is difficult to quickly verify the processing algorithms such as target state estimation based on photometric data under the dynamic movement of space targets. This limits the deeper and more comprehensive research on space targets, and there is an urgent need to develop more advanced measurement systems and experimental methods to break through the existing bottlenecks and improve the research level of space targets. Summary of the Invention

[0004] The main object of the present invention is to propose a ground experimental system for dynamically measuring the photometric characteristics of space targets, aiming to at least solve the related technical problems mentioned in the related art.

[0005] To achieve the above object, a ground experimental system for dynamically measuring the photometric characteristics of space targets proposed by the present invention includes:

[0006] A controllable turntable with multiple degrees of freedom, on which a scaled-down model of a satellite is connected, and the controllable turntable is used to drive the scaled-down model of the satellite to rotate and adjust at multiple angles;

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

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

[0009] A master control unit, which is communicatively connected to the controllable turntable, the visible light detection unit and the light source unit;

[0010] Wherein, the master control unit is used to control the light source intensity, the movement parameters of the turntable and image acquisition, and perform downsampling processing on the image data to generate a photometric sequence simulating long-distance observation.

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

[0012] An azimuth axis for realizing continuous rotation from 0 to 360°;

[0013] An elevation axis for realizing angle adjustment of ±45°; and

[0014] A roll axis for realizing angle adjustment of ±180°;

[0015] Wherein, the repeat positioning accuracy of the controllable turntable is ≤0.005°, and it supports programming control of angular velocity and angular acceleration.

[0016] In an embodiment of the present invention, the controllable turntable includes:

[0017] A base, on which an azimuth drive unit is provided, and a first connecting frame is connected to the azimuth drive unit;

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

[0019] An elevation drive unit, which is connected to the second connecting frame, and a third connecting frame is connected to the elevation drive unit, and the satellite scaled model is connected to the third connecting frame;

[0020] Wherein, the azimuth drive unit, the roll drive unit and the elevation drive unit are respectively communicatively connected to the master control unit.

[0021] In an embodiment of the present invention, the shape, size and surface material of the satellite scaled model 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 for simulating the reflection characteristics of different materials.

[0022] In an embodiment of the present invention, the visible light detection unit is a visible light camera, and the visible light camera includes:

[0023] An image acquisition unit and a simulation unit;

[0024] Wherein, the image acquisition unit is used for imaging the satellite model, and the simulation unit is used for downsampling the image through a target area extraction algorithm to generate simulated observation images of targets of different sizes to equivalent the long-distance observation effect.

[0025] In an embodiment of the present invention, the light source unit includes:

[0026] A box body, inside which there is a light source cavity, in which a reflecting bowl and a xenon light source are installed, and the xenon light source is located at the focus of the reflecting bowl;

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

[0028] An integrating mirror, arranged on the reflection optical path of the reflecting mirror, for homogenizing the light beam intensity; and

[0029] A lens group, including a plurality of lenses, for collimating the light beam into parallel light and irradiating it on the satellite scaled model.

[0030] In an embodiment of the present invention, the master control unit includes:

[0031] An image processing module, for extracting the target area and downsampling the resolution of the extended target image collected by the visible light camera, and generating a simulated observation image of a patchy or dot-like target; and

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

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

[0034] The present invention also provides a method for dynamically measuring the space target photometry of any of the above-mentioned systems, which includes:

[0035] S1. Set the radiation intensity of the simulated light source and the attitude motion parameters of the controllable turntable through the master control unit;

[0036] S2. Control the controllable turntable to drive the satellite scaled model to perform three-axis continuous rotation to simulate the dynamic attitude change of the target;

[0037] S3. Use the visible light camera to collect the reflected light image sequence of the satellite scaled model;

[0038] S4. Perform target area extraction and downsampling processing on the image sequence through the experimental master control system to generate a photometric curve for equivalent long-distance observation;

[0039] S5. Input the photometric curve into the non-cooperative target characteristic analysis algorithm to invert the motion parameters and surface characteristics of the target.

[0040] In an embodiment of the present invention, the downsampling process in step S4 includes: performing Gaussian blur and pixel merging operations on the extended target image, so that the imaging size of the target in the image is smaller than a preset threshold.

[0041] In summary, the present invention provides a ground experimental system for photometric dynamic measurement of space targets. The multi-degree-of-freedom controllable turntable can accurately simulate the dynamic attitude changes of space targets, providing experimental conditions close to real scenarios for photometric characteristic analysis. Through image downsampling processing and photometric calibration algorithms, the experimental data within a limited distance is converted into equivalent long-distance observation results, significantly improving the fidelity of the ground-based telescope simulation. The highly parallel beam generated by the light source unit simulates the irradiation characteristics of sunlight, ensuring the true reproduction of the reflection characteristics of the target surface. By replacing some on-orbit actual measurements with ground experiments, the space mission cost is significantly reduced. At the same time, uncontrollable factors such as atmospheric turbulence and weather interference in real observations are avoided, effectively improving the stability of experimental data. At the same time, through normalized gray processing and dynamic light source adjustment technology, equipment noise and environmental interference can be effectively suppressed, meeting the requirements of high-precision situation awareness.

[0042] It can effectively achieve high-fidelity simulation and efficient analysis of the photometric dynamic characteristics of space targets, providing reliable technical support for space target recognition, orbit prediction, and stealth technology verification, and combining innovation, practicality, and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0044] Figure 1 It is a three-dimensional structure schematic diagram of an embodiment of a ground experimental system for photometric dynamic measurement of space targets provided by the present invention;

[0045] Figure 2 It is a structure schematic diagram of the controllable turntable of a ground experimental system for photometric dynamic measurement of space targets provided by the present invention in an embodiment;

[0046] Figure 3 It is a structure schematic diagram of the visible light detection unit of a ground experimental system for photometric dynamic measurement of space targets provided by the present invention in an embodiment;

[0047] Figure 4 It is a module schematic diagram of the total control unit of a ground experimental system for photometric dynamic measurement of space targets provided by the present invention in an embodiment;

[0048] Figure 5 Schematic flow chart of a method for dynamically measuring the photometric properties of space targets provided by the present invention in an embodiment.

[0049] Explanation of the reference numerals in the accompanying drawings:

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

[0051] 200, satellite scaled model;

[0052] 300, visible light detection unit;

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

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

[0055] The implementation, functional features, and advantages of the objectives of the present invention will be further described in conjunction with the embodiments and with reference to the accompanying drawings. Specific embodiments

[0056] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0057] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0058] In addition, if there are descriptions such as "first" and "second" involved in the embodiments of the present invention, the descriptions of "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature.

[0059] Please refer to Figures 1 to 4, the present invention provides a ground experimental system for dynamic photometric measurement of space targets, which can be used to improve the current poor effect of photometric measurement of space targets.

[0060] Specifically, the ground experimental system for dynamic photometric measurement of space targets mentioned in the present invention includes 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 master control unit 500. Among them, 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 its attitude in space. The light source unit 400 and the visible light detection unit 300 are located outside the controllable turntable 100. The light source unit 400 can be used to simulate the parallel light source of the sun, and this light source is directly irradiated on the satellite scaled model 200.

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

[0062] It should be noted that the master control unit 500 is communicatively connected to the controllable turntable 100, the visible light detection unit 300, and the light source unit 400, and the master control unit 500 can be used to control the light source intensity, the movement parameters of the turntable, and image acquisition. The master control unit 500 can perform downsampling processing on the image data and generate a photometric sequence simulating long-distance observation.

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

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

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

[0066] Furthermore, the controllable turntable 100 further includes a base 110, an azimuth drive unit 120, a roll drive unit 130, and a pitch drive unit 140. The base 110 serves as the fixed support part of the turntable and is installed on the experimental platform to ensure the stability of the overall structure. The azimuth drive unit 120 is installed on the base 110 and is used to drive the first connecting frame 121 to rotate around the azimuth axis, and the rotation range is from 0 to 360°. The first connecting frame 121 connects the azimuth drive unit 120 and the roll drive unit 130 and is used to transmit the movement of the azimuth axis.

[0067] Further, the roll drive unit 130 is installed on the first connecting frame 121 and is used to drive 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 drive unit 130 and the pitch drive unit 140 and is used to transfer the motion of the roll axis.

[0068] The pitch drive unit 140 is installed on the second connecting frame 131 and is used to drive 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 drive unit 140 and the satellite scaled model 200 and is used to transfer the motion of the pitch axis.

[0069] It can be foreseen that the satellite scaled model 200 is fixed on the third connecting frame 141 and is used to simulate the photometric characteristics of real space targets.

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

[0071] The roll drive unit 130 is driven by a servo motor and is equipped with a torque sensor to ensure smooth movement of the roll axis within the range of ±180°. The motor is connected to the second connecting frame 131 through a coupling and supports precise control of angular velocity and angular acceleration. And the pitch drive unit 140 uses a DC brushless motor and is equipped with a high-resolution encoder to ensure precise positioning of the pitch axis within the range of ±45°. The motor is connected to the third connecting frame 141 through a gearbox and supports fast response and high stability. The master control unit 500 can be connected to the azimuth drive unit 120, the roll drive unit 130, and the pitch drive unit 140 through the RS-485 communication protocol to send control commands in real time and receive feedback data.

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

[0073] For example, if the target is a cube satellite with dimensions of 2 m × 2 m × 2 m, the scaled model is reduced by a ratio of 1:10 to 0.2 m × 0.2 m × 0.2 m. The surface material of the model is specially treated and is divided into a diffuse reflection coating area and a specular reflection coating area to simulate the reflection characteristics of different components of a real satellite.

[0074] The diffuse reflection coating area uses a white paint with a high reflectivity (such as Spectra l on material), and its bidirectional reflectance distribution function (BRDF) is close to the Lambertian characteristics, which is used to simulate the scattering reflection of the solar panel or the satellite body. The specular reflection coating area uses a high-gloss aluminum film or silver-plated material, and its BRDF exhibits strong specular reflection characteristics, which is used to simulate the specular reflection effect of the satellite antenna or the metal shell. Through this design, the scaled model can accurately reproduce the photometric characteristics of real space targets under different lighting conditions, providing high-fidelity simulation data for ground experiments. Based on this, the parallel light beam generated by the light source unit 400 irradiates the surface of the scaled model, the visible light detection unit 300 collects the reflected light image sequence, and the overall control unit 500 performs photometric calibration and data analysis, and finally generates a photometric curve for equivalent long-distance observation, 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 uses a high-resolution visible light camera, and its core functions are jointly realized by the image acquisition unit and the simulation unit.

[0076] Specifically, the image acquisition unit is equipped with a high-sensitivity CMOS sensor and an adjustable-focus optical lens, which are used to perform high-frame-rate imaging on the satellite scaled model 200 to capture the reflected light image sequence of the target in the dynamic motion state. The simulation unit is integrated inside the camera, and processes the original image through the target area extraction algorithm. First, it identifies and extracts the target area of the satellite scaled model 200, and then uses Gaussian blur and pixel merging techniques to perform downsampling processing on the image to generate simulated observation images of different-sized targets.

[0077] For example, the target area of 100×100 pixels in the original image is downsampled to a 10×10 pixel patch target, or further downsampled to a single-pixel point target, to simulate the imaging effect of a ground-based telescope under long-distance observation conditions. Through this processing method, the visible light detection unit 300 can simulate the observation characteristics of the target at different distances, providing high-fidelity experimental data for space target recognition and photometric characteristic analysis. Based on this, the overall control unit 500 can receive and process the simulated observation images generated by the visible light detection unit 300 in real time, and combine the algorithm of the photometric calibration module 520 to generate a photometric sequence for equivalent long-distance observation, 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 highly parallel light beam to simulate the irradiation conditions of the solar light source. The core components of the light source unit 400 include a box body 410, a reflector bowl 412, a xenon light source 413, a reflector 414, an integrating mirror 415, and a lens group 416.

[0079] Inside the box body 410, there is a light source cavity 411. A parabolic reflector 412 is installed in the light source cavity 411, and the xenon light source 413 is precisely installed at the focus of the reflector 412 to ensure that the light forms a parallel beam after reflection. The reflector 414 is arranged above the reflector 412 at an inclination angle of 45°, and reflects the beam emitted by the xenon light source 413 to the integrating mirror 415. The integrating mirror 415 adopts a microlens array design and is used to homogenize the beam intensity distribution and eliminate the hot spot effect. The lens group 416 is composed of multiple achromatic lenses and is used to further collimate the beam and adjust the spot size, and finally generate a highly parallel beam to irradiate on the satellite scaled model 200.

[0080] It can be understood that the light source unit 400 can accurately simulate the irradiation conditions of the solar light source in the experimental environment and provide a highly stable and highly uniform illumination environment for the dynamic photometric measurement of space targets. In the experiment, the master control unit 500 dynamically controls the light source output power by adjusting the current intensity of the xenon light source 413 to meet the requirements of different experimental scenarios.

[0081] In some embodiments, the master control unit 500 realizes the real-time processing and calibration of the dynamic photometric measurement data of the space target through the collaborative work of the image processing module 510 and the photometric calibration module 520.

[0082] Among them, the image processing module 510 receives the extended target image (such as the original image of 1000×1000 pixels) collected by the visible light detection unit 300.

[0083] First, use the target area extraction algorithm (such as ROI segmentation based on edge detection) to identify and crop the reflected light area of the satellite scaled model 200.

[0084] Subsequently, adopt Gaussian blur (kernel size of 5×5 pixels) and pixel merging technology (such as merging a 10×10 pixel area into 1 pixel) to downsample the original high-resolution image into a speckled target (such as 50×50 pixels) or a point target (single pixel) to simulate the imaging characteristics of a ground-based telescope in long-distance observation.

[0085] The photometric calibration module 520 can convert the gray value of the downsampled image into equivalent long-distance observation photometric 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 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 allows the master control unit 500 to adjust the current intensity of the xenon light source 413 according to the target attitude (such as the solar phase angle θ = 30°). Its 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] It is allowed to combine the BRDF data of the surface material of the satellite scaled model 200 to calculate the reflected radiation intensity of the target under specific observation geometries. Through geometric attenuation correction and the atmospheric transmission model, the limited-distance photometric data from ground experiments are converted into equivalent long-distance observation values to generate a continuous photometric curve.

[0090] Specifically, in the actual processing, the following steps are allowed.

[0091] First, normalize the image grayscale values.

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

[0093] where, I max and I min are the minimum and maximum grayscale values of the image respectively. Based on the above method, through this formula, the grayscale values of all pixels are linearly mapped to the range of [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 may cause differences in the original grayscale values, after normalization, the dimension can be unified, facilitating cross-device data comparison. And the normalized data is more easily combined with physical models (such as BRDF, radiative transfer equation) to improve the calculation efficiency.

[0096] Convert the grayscale values to radiation intensity.

[0097] It is allowed to calculate the reflected radiation intensity I 光源 of the target surface according to the light source intensity I 反射 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, based on the light source-target distance d 光源 and the target-camera distance d 相机 , calculate the geometric attenuation factor I 几何 (x,y).

[0101] Through the formula:

[0102] Furthermore, based on the atmospheric attenuation coefficient α and the equivalent atmospheric path length d 大气 , calculate the atmospheric attenuation factor I 大气 (x,y).

[0103] Through the formula:

[0104] Finally, obtain the equivalent long-distance luminous intensity I 等效 (x,y).

[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, repeat the above steps for each frame of the image to generate a continuous luminous intensity sequence {I 等效 (t)}, which is used for subsequent analysis of the spatial target characteristics.

[0108] It should be noted that during the actual experiment, the master control unit 500 is allowed to control the controllable turntable 100 to drive the satellite scaled model 200 to tumble at an angular velocity of 10° / s, and at the same time dynamically adjust the radiation intensity of the xenon light source 413. Compare the average deviation between the finally generated luminous intensity sequence and the measured data of the ground-based telescope, and determine whether the deviation comparison value is less than a preset value to verify the simulation accuracy and algorithm reliability of the system.

[0109] Please refer to Figure 5 , the present invention also provides a method for dynamically measuring the luminous intensity of a spatial target by applying the spatial target luminous intensity dynamic measurement ground experiment system described in any one of the above.

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

[0111] S1. Set the radiation intensity of the simulated light source and the attitude motion parameters of the controllable turntable 100 through the master control unit 500.

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

[0113] S2. Control the controllable turntable 100 to drive the satellite scaled model 200 to perform three-axis continuous rotation, simulating the dynamic attitude changes of the target. The controllable turntable 100 drives the satellite scaled model 200 to perform three-axis continuous motion, simulating the dynamic attitude changes such as on-orbit tumbling and spinning of the target. At the same time, the light source unit 400 generates parallel light beams to irradiate the model surface.

[0114] S3. Use a visible light camera to collect a sequence of reflected light images of the satellite scaled 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 4096×4096 pixels, covering the full attitude cycle of the target.

[0115] S4. Through the experimental master control system, perform target area extraction and downsampling processing on the image sequence to generate a photometric curve for equivalent 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 scaled model 200 and crop out the target area (such as 1024×1024 pixels).

[0119] S402. Downsampling processing.

[0120] Perform Gaussian blur (σ = 2.0) and 4×4 pixel merging on the target area to generate a speckled target image of 256×256 pixels, or further downsample it to a single-pixel point target.

[0121] S403. Photometric curve generation.

[0122] The photometric calibration module 520 combines the light source intensity, BRDF model, and atmospheric attenuation parameters to convert the gray value into an equivalent long-distance photometric value and 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 invert the motion parameters and surface characteristics of the target.

[0124] In step S5, it includes:

[0125] S501. Motion parameter extraction.

[0126] Perform a Fourier transform on the photometric curve, extract the peak frequency (such as 2 Hz) as the target spin frequency, and calculate the attitude angle change through phase analysis.

[0127] S502, Surface characteristic identification.

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

[0129] In summary, the present invention provides a ground experimental system for dynamic photometric measurement of space targets. The dynamic attitude change of space targets can be accurately simulated by the multi-degree-of-freedom controllable turntable 100, providing experimental conditions close to the real scene for photometric characteristic analysis. Through image downsampling processing and photometric calibration algorithm, the experimental data within a limited distance is converted into equivalent long-distance observation results, significantly improving the fidelity of the ground-based telescope simulation. The highly parallel beam generated by the light source unit 400 simulates the irradiation characteristics of sunlight, ensuring the true reproduction of the reflection characteristics of the target surface. By replacing part of the on-orbit actual measurement with ground experiments, the space mission cost is significantly reduced. At the same time, uncontrollable factors such as atmospheric turbulence and weather interference in real observations are avoided, which can effectively improve the stability of experimental data. At the same time, through normalized gray processing and dynamic light source adjustment technology, equipment noise and environmental interference can be effectively suppressed, meeting the requirements of high-precision situation awareness.

[0130] It can effectively achieve high-fidelity simulation and efficient analysis of the dynamic photometric characteristics of space targets, providing reliable technical support for space target recognition, orbit prediction, and stealth technology verification, and combining innovation, practicability, and economy.

[0131] The above is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A ground experimental system for dynamic measurement of space target photometry, characterized in that: include: A controllable turntable (100) with multiple degrees of freedom, a satellite scale model (200) being connected to the controllable turntable (100), and the controllable turntable (100) being used to drive the satellite scale model (200) to rotate and adjust at multiple angles; A visible light detection unit (300) is located in the direction of the reflected light path of the satellite scaled model (200), and is used to image the satellite scaled 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 irradiated onto the satellite scale model (200); as well as A main control unit (500) is communicatively connected with the controllable turntable (100), the visible light detection unit (300) and the light source unit (400); The master control unit (500) is used to control the light source intensity, turntable motion parameters and image acquisition, and to perform downsampling processing on image data to generate a photometric sequence simulating long-distance observation.

2. The ground experiment system for dynamic measurement of space target photometry according to claim 1 is characterized in that: The controllable turntable (100) is a three-degree-of-freedom turntable, comprising: Azimuth axis, used to achieve continuous rotation from 0 to 360°; A pitch axis for achieving ±45° angle adjustment; and Roll axis, used to achieve ±180° angle adjustment; The controllable turntable (100) has a repeat positioning accuracy of ≤0.005° and supports programmed control of angular velocity and angular acceleration.

3. The ground experiment system for dynamic measurement of space target photometry according to claim 2 is characterized in that: The controllable turntable (100) comprises: A base (110), wherein an azimuth driving unit (120) is disposed on the base (110), and a first connecting frame (121) is connected to the azimuth driving unit (120); A rolling drive unit (130) connected to the first connecting frame (121), and the rolling drive unit (130) is connected to a second connecting frame (131); and A pitch driving unit (140) is connected to the second connecting frame (131), and a third connecting frame (141) is connected to the pitch driving unit (140), and the satellite scale model (200) is connected to the third connecting frame (141); The azimuth drive unit (120), the roll drive unit (130) and the pitch drive unit (140) are respectively connected to the master control unit (500) for communication.

4. The ground experiment system for dynamic measurement of space target photometry according to claim 1 is characterized in that: The shape, size and surface material of the satellite scaled model (200) maintain geometric similarity with the real space target to be simulated, and the surface material includes a diffuse reflection coating area and a specular reflection coating area for simulating the reflection characteristics of different materials.

5. The ground experiment system for dynamic measurement of space target photometry according to claim 1 is characterized in that: The visible light detection unit (300) is a visible light camera, which comprises: Image acquisition unit and simulation unit; Among them, the image acquisition unit is used to image the satellite model, and the simulation unit is used to downsample the image through the target area extraction algorithm to generate simulated observation images of targets of different sizes to achieve equivalent long-distance observation effects.

6. The ground experiment system for dynamic measurement of space target photometry according to claim 1 is characterized in that: The light source unit (400) comprises: A box (410), wherein a light source cavity (411) is disposed in the box (410), a reflective bowl (412) and a xenon light source (413) are installed in the light source cavity (411), and the xenon light source (413) is located at the focus of the reflective bowl (412); A reflector (414) is disposed above the reflector bowl (412) at an angle of 45° and is used to reflect the light beam emitted by the xenon lamp light source (413) to the integrating mirror (415); an integrating mirror (415), arranged on the reflected light path of the reflecting mirror (414), and used for uniformizing the intensity of the light beam; and The lens group (416) includes a plurality of lenses and is used to collimate the light beam into parallel light and irradiate the parallel light onto the satellite scale model (200).

7. The ground experiment system for dynamic measurement of space target photometry according to claim 1 is characterized in that: The master control unit (500) comprises: An image processing module (510) is used to extract the target area and perform resolution downsampling on the extended target image collected by the visible light camera to generate a simulated observation image of a spot-like or point-like target; and The photometric calibration module (520) is used to convert the grayscale value of a target within a limited distance into equivalent long-distance observation photometric information according to the light source intensity parameter and the atmospheric attenuation model.

8. The ground experiment system for dynamic measurement of space target photometry according to claim 7 is characterized in that: The photometric calibration module (520) dynamically adjusts the radiation intensity of the xenon lamp light source (413) and combines the bidirectional reflection distribution function model of the target surface material to achieve equivalent simulation of the target photometric characteristics under different solar phase angles.

9. A method for dynamic measurement of the photometric intensity of a space target applied to the ground experimental system for dynamic measurement of photometric intensity of a space target as claimed in any one of claims 1 to 8, characterized in that: include: S1. Setting the radiation intensity of the simulated light source and the posture motion parameters of the controllable turntable (100) through the master control unit (500); S2. Controlling the controllable turntable (100) to drive the satellite scale model (200) to perform three-axis continuous rotation to simulate the dynamic attitude change of the target; S3. Using a visible light camera to collect a reflected light image sequence of a satellite scaled model (200); S4. The target area is extracted and downsampled from the image sequence through the experimental master control system to generate a photometric curve equivalent to long-distance observation; S5. Input the photometric curve into the non-cooperative target characteristic analysis algorithm to invert the motion parameters and surface characteristics of the target.

10. The method for dynamic measurement of space target photometry according to claim 9, characterized in that: The downsampling process in step S4 includes: Gaussian blur and pixel merging operations are performed on the extended target image so that the imaging size of the target in the image is smaller than a preset threshold.

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