A calculation method for the radiation characteristics of a target throughout its life cycle

Abstract

The present invention discloses a method for calculating the radiation characteristics of a target throughout its life cycle, which relates to the field of infrared signal technology and aims to accurately simulate the changes in the radiation characteristics of the target during its life cycle. The method includes the following steps: First, construct a three-dimensional model of the target and analyze its orbital and motion characteristics; Second, use UG finite element analysis to calculate the temperature field of the target; Then, perform the conversion of the target coordinate system; Next, calculate the projected area of the target at different time points; Finally, calculate the radiation characteristics of the target throughout its life cycle based on data such as the temperature field and the projected area. Through the above steps, the present invention can comprehensively and accurately describe the process of the target radiation characteristics changing with time, is applicable to fields such as aerospace, aviation, and military, and has important engineering application value.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared signal, and particularly to an infrared radiation dynamic characteristic simulation method based on the full life cycle of space targets. Background Art

[0002] With the continuous progress of space technology, the complex motion states of space targets in orbit have had a significant impact on their radiation characteristics. Especially in the analysis of infrared radiation characteristics, the orbital changes, attitude changes of the target, and the radiation influence of the surrounding environment require precise dynamic simulation. The existing infrared radiation simulation methods mainly focus on static or simplified models, lacking a comprehensive consideration of the infrared radiation changes of space targets throughout their life cycle.

[0003] In the prior art, many simulation methods mainly consider the radiation characteristics of the target in a fixed orbit or attitude, usually assuming that the target surface is in a static state, or only considering the radiation intensity change at a certain time point. Most of these methods ignore the micro-motion effect that may occur during the orbital operation of space targets, resulting in insufficient accuracy of radiation calculation. Especially in complex orbits and non-uniform radiation environments, the existing methods cannot accurately simulate the changes in the radiation intensity and radiation angle coefficient of target surface micro-elements at different time points. In addition, the existing simulation models usually do not comprehensively consider the influences of various radiation sources such as solar radiation, earth-reflected radiation, and deep-space background radiation, often adopting simplified assumptions and failing to fully consider the dynamic changes of radiation sources and the changes in the relative positions of space target surfaces. Due to the lack of consideration of these complex factors, the prior art is difficult to meet the requirements of high-precision infrared radiation characteristic analysis. Especially when accurately simulating the radiation dynamic characteristics of targets in the space environment, the error is large and sufficient accurate data support cannot be provided.

[0004] To meet the high-precision requirements for the analysis of space target radiation characteristics, especially the radiation dynamic simulation of targets throughout their life cycle in complex space environments, the existing technical methods urgently need a simulation method that can comprehensively, dynamically, and accurately simulate the infrared radiation characteristics of targets. Therefore, how to provide an infrared radiation dynamic characteristic simulation method that can consider the orbital motion, attitude changes, micro-motion effect, and complex radiation environment of space targets throughout their life cycle has become a difficult problem to be solved in the current technical field. Summary of the Invention

[0005] The present invention provides a radiation characteristic calculation method for the full life cycle of a target, aiming to accurately simulate the changes in the radiation characteristics of the target throughout its life cycle and having high application value.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for calculating the radiation characteristics of a target throughout its life cycle, comprising the following steps:

[0008] S1. Target modeling and analysis of motion characteristics: Construct a geometric model of the target, and combine the orbit parameters and motion characteristics of the target to describe the motion trajectory and spatial position changes of the target during its life cycle, and perform grid division on the outer surface of the target;

[0009] S2. Temperature field analysis: Perform finite element analysis on the model after grid division, calculate the temperature field, and predict the temperature distribution on the target surface;

[0010] S3. Coordinate system conversion and calculation of projected area: Convert the calculation results from the body coordinate system to the J2000 coordinate system, and further calculate the projected area of the target at different time points based on the geometric characteristics and motion trajectory of the target;

[0011] S4. Calculate the radiation characteristics of the target throughout its life cycle based on the temperature field, projected area of the target, and relevant data after coordinate system conversion:

[0012] S401. First, determine whether the target is in the sunlit area or the shadow area;

[0013] S402. If the target is in the sunlit area, calculate the solar radiation view factor of the target surface element, calculate the radiance of the target surface element based on the solar irradiance and the solar radiation view factor, and further calculate the solar radiation intensity absorbed by the target surface; ;

[0014] S403. Calculate the earth radiation view factor, calculate the amount of earth infrared radiation received by the target surface element based on the earth irradiance and the earth radiation view factor, and further calculate the earth radiation intensity reflected by the target surface; ;

[0015] S404. If the target is in the sunlit area, calculate the earth-reflected solar radiation view factor, and further calculate the amount of earth-reflected solar infrared radiation received by the target surface element based on the earth albedo, solar irradiance, and the earth-reflected solar radiation view factor, and further calculate the earth-reflected solar radiation intensity reflected by the target surface element; ;

[0016] S405. Calculate the self-thermal radiation of the target based on the self-radiation amount of the target; ;

[0017] S406. Finally, calculate the total radiation intensity of the target :

[0018]

[0019] Further, by calculating the angle between the normal vector of the target surface element and the detector's line of sight, it is determined whether each surface element is within the field of view of the detector. For all surface elements within the detector's field of view, their projected areas are summed to obtain the total projected area of the target surface.

[0020] Further, let the position vector of the target be , and the solar unit radiation vector in the J2000 protocol coordinate system be . It is determined whether the target is in the shadow area:

[0021]

[0022] where is the radius of the Earth.

[0023] Further, let the normal vector of the target surface microelement be , and the radiation view factor between the target and the sun be:

[0024]

[0025] The sun is equivalent to a blackbody at 5900K, and its irradiance is:

[0026]

[0027] where is the wavelength, is the first radiation constant, is the second radiation constant, is the radius of the sun, is the average sun-earth distance;

[0028] The radiance of the target surface element is:

[0029]

[0030] where is the absorptivity of the surface element to solar radiation;

[0031] For the target surface element , at time , the solar radiation intensity reflected by the target surface is:

[0032]

[0033] where is the area of this surface element, is the rotation matrix of the target at time t, is the normal vector of the target surface element , LOS is the normal vector of the detector's detection direction, is the cosine value of the angle between the normal vector of the target surface element and the detection normal vector of the detector. is the radiance of the surface element, and B is the set of surface elements in the detection field of view.

[0034] Further, in step S403, the infrared irradiance of the earth is:

[0035]

[0036] where is the radius of the earth, and h is the flight altitude of the target;

[0037] The amount of infrared radiation from the earth received by the surface element of the target is:

[0038]

[0039] where is the reflectivity of the surface element to the earth's radiation; is the radiation view factor of the target reflecting the earth's radiation, which is calculated by the angle between the normal vector of the surface element and the vector from the center of the earth to the center of the surface element.

[0040] Further, in step S404, the formula for calculating the radiation view factor of the earth reflecting solar radiation is as follows:

[0041]

[0042] where is the angle between the line connecting the center of the earth and the centroid of the target surface element and the sun. When , it indicates that the target is flying in the solar illumination area. When , it indicates that the target is flying in the shadow area;

[0043] The intensity of the earth-reflected solar radiation reflected by the surface element of the target surface is:

[0044]

[0045] where is the earth reflectivity.

[0046] Further, in step S405,

[0047] The self-thermal radiation of the target is:

[0048]

[0049]

[0050] where is the infrared emissivity of the surface element, is the target surface element The temperature at time t, within the wavelength band , is the radiance of target surface element i.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1. High precision: By comprehensively considering the target's motion trajectory, temperature field distribution, and micro-motion effect, it provides more accurate infrared radiation simulation results, which can truly reflect the radiation changes of the target throughout its life cycle.

[0053] 2. Strong adaptability: This method can adapt to the simulation requirements of different types of space targets and can be applied to radiation calculations under various environmental conditions, being widely applicable to fields such as aerospace, aviation, and military.

[0054] 3. Comprehensiveness: It not only considers traditional solar radiation and earth-reflected radiation but also incorporates the target's micro-motion effect into the simulation, providing more complete radiation characteristic data to ensure accurate analysis in complex space environments.

[0055] 4. Strong data support: It provides reliable data support for the radiation management and control of the target, which can help engineering and technical personnel in related fields optimize the design and implementation plan. Description of the Drawings

[0056] Figure 1 is a flowchart of a method for calculating the radiation characteristics of a target throughout its life cycle;

[0057] Figure 2 is a schematic diagram of the target projected area of a method for calculating the radiation characteristics of a target throughout its life cycle;

[0058] Figure 3 is a schematic diagram of the radiance of the target surface element of a method for calculating the radiation characteristics of a target throughout its life cycle;

[0059] Figure 4 is a schematic diagram of the spectral radiation intensity of the target of a method for calculating the radiation characteristics of a target throughout its life cycle;

[0060] Figure 5 is a schematic diagram of the spectral radiance of the target of a method for calculating the radiation characteristics of a target throughout its life cycle;

[0061] Figure 6 is a schematic diagram of the proportion of infrared radiation in the space environment of a method for calculating the radiation characteristics of a target throughout its life cycle;

[0062] Figure 7 is a schematic diagram of the total directional radiation intensity of the target of a method for calculating the radiation characteristics of a target throughout its life cycle;

[0063] Figure 8 It is a GUI input interface for calculating the radiation characteristics throughout the current life cycle;

[0064] Figure 9 It is an output result interface for calculating the radiation characteristics throughout the current life cycle. Specific implementation manners

[0065] The present invention will be further described in detail below in conjunction with the accompanying drawings and implementation manners:

[0066] As Figure 1 shown, a method for calculating the radiation characteristics of a target throughout its life cycle includes the following steps:

[0067] S1. Target modeling and motion characteristic analysis: First, an accurate geometric model of the target is constructed through 3D modeling technology. Combining the orbital parameters and motion characteristics of the target, the motion trajectory and spatial position changes of the target throughout its life cycle are comprehensively described.

[0068] Since the projected area of the target in the line-of-sight direction of the detector is usually smaller than its actual surface area, in order to more accurately describe the projected area of the target, it is necessary to perform meshing on the outer surface of the target, usually in the way of dividing it with triangular micro-elements. This process provides a basis for calculating the temperature distribution on the outer surface of the target.

[0069] S2. Temperature field analysis: Second, the UG finite element analysis software is used to calculate the temperature field. By comprehensively considering factors such as heat conduction, radiation, and convection of the target under different environmental conditions, the temperature distribution on the surface of the target is accurately predicted.

[0070] S3. Coordinate system conversion and projected area calculation: The coordinate system of the target is converted, and the calculation results are converted from the body coordinate system to the J2000 coordinate system. Based on the geometric characteristics and motion trajectory of the target, the projected area of the target at different time points is further calculated. Considering the relative motion between the target and the detector, and the target may be in a micro-motion state, it is necessary to calculate the angle between the normal vector of the target surface element and the line of sight of the detector to determine whether each surface element is within the field of view of the detector. For all surface elements within the field of view of the detector, their projected areas are added up to obtain the total projected area of the target surface.

[0071] S4. Radiation characteristic calculation: Finally, based on the temperature field, projected area of the target, and relevant data after coordinate system conversion, the radiation characteristics of the target throughout its life cycle are calculated.

[0072] S401. First, determine whether the target is located in the sunny area. The sunny area can receive solar radiation, while the shaded area cannot directly obtain solar radiation. Therefore, it is necessary to determine whether the target is in the shaded area during flight in order to accurately calculate the amount of solar radiation it absorbs and reflects. Given the radius of the Earth , let the position vector of the target be , and the unit solar radiation vector in the J2000 protocol coordinate system be : Determine whether the target is in the shaded area:

[0073]

[0074] Since the distance between the sun and the Earth is much greater than the distance between the target and the Earth's center, the solar irradiance on the target surface can be approximated as the solar irradiance reaching the Earth's surface.

[0075] S402. The infrared irradiance of the sun at the target is . The solar radiation view factor represents the proportion of solar radiation incident on the surface element of the target. The amount of solar radiation absorbed by the target surface is closely related to this view factor. Let the normal vector of the microelement on the target surface be , and the angle between the target and the sun be:

[0076]

[0077] The sun can be approximated as a blackbody at 5900K, and its irradiance is:

[0078]

[0079] where is the wavelength, is the first radiation constant, , is the second radiation constant, , is the radius of the sun, is the average sun-earth distance;

[0080] Then, for the target surface element , at time , the intensity of the solar radiation reflected by the target surface is:

[0081]

[0082]

[0083] where is the reflectivity of the surface element to solar radiation, is the area of this surface element, is the radiance of the surface element, is The rotation matrix of the moment target is the normal vector of the target surface element , LOS is the normal vector of the detector detection direction, is the cosine value of the angle between the normal vector of the target surface element and the normal vector of the detector detection direction, and B is the set of surface elements in the detection field of view.

[0084] S403. Similar to the solar radiation angle factor, the terrestrial radiation angle factor represents the projection ratio of terrestrial radiation energy on the surface element of the target. The amount of terrestrial infrared radiation received by the surface element of the target is:

[0085]

[0086] Among them, is the reflectivity of the surface element to terrestrial radiation, is the radiation angle factor of the target reflecting terrestrial radiation, which can be calculated through the angle between the normal vector of the surface element and the vector from the center of the earth to the center of the surface element. is the infrared irradiance of the earth:

[0087]

[0088] Among them, is the radius of the earth , and h is the flight altitude of the target.

[0089] The intensity of terrestrial radiation reflected by the target surface is:

[0090]

[0091] S404. Affected by factors such as cloud cover and surface reflection, part of the solar radiation will be reflected. This part of the radiation is called the earth-reflected solar radiation, which is mainly concentrated in the visible light to short-wave infrared band. The earth-reflected solar radiation angle factor represents the projection ratio of the reflected radiation energy on the surface element of the target, and its calculation formula is as follows:

[0092]

[0093] Among them, is the angle between the line connecting the center of the earth and the centroid of the target surface element and the sun. When , it indicates that the target is flying in the solar illumination area. When , it indicates that the target is flying in the shadow area.

[0094] The intensity of the earth-reflected solar radiation reflected by the surface element of the target is:

[0095]

[0096] Among them, is the Earth's albedo.

[0097] Since the Moon and other stars are far from the space target, the energy they radiate to the target surface is extremely weak and can be ignored; and the radiation of the deep space background can also be regarded as negligible due to its low temperature.

[0098] S405. The self-thermal radiation of the target is:

[0099]

[0100]

[0101] Among them, is the infrared emissivity of the surface element, is the temperature of the target surface element i, is at moment, in the band , the radiance of the target surface element i.

[0102] S406. The total radiation intensity of the target is:

[0103]

[0104] In this embodiment, first configure the geometric characteristics of the target, select a conical target, and set its orbital characteristics, attitude motion parameters, and flight altitude data; then define the thermophysical characteristics of the target, including surface emissivity, solar radiation absorptivity, and Earth radiation absorptivity, and import the target surface temperature distribution data; at the same time, set the space background radiation environment, including the equivalent blackbody temperatures of solar radiation, Earth radiation, and deep space background; then input the position vector and line-of-sight direction vector of the detector to establish the relative geometric relationship between the detector and the target; finally, set the detection band to the mid-wave infrared range of 3 - 5 to complete the parameter configuration of the entire simulation system.

[0105] Then calculate the projected area of the target under the detector's field of view. As Figure 2 shown, it is the projected area of the target at time, which is 0.31207 square meters and is located in the solar illumination area, and is directly affected by solar radiation at this time. After obtaining the target projected area, the radiation characteristics can be further calculated. Figure 3 is the radiance curve of the target surface element. The abscissa is the number of surface elements, and the ordinate is the radiance. Five curves of the target's self-thermal radiation, reflected solar radiation, reflected solar radiation reflected by the Earth, reflected Earth radiation, and total radiation are respectively plotted in the figure. Figure 4 is the spectral radiation intensity of the target, indicating at different times The target spectral radiation intensity curve. Figure 5 is the surface element The average radiance of the band, Figure 6 is the curve of the proportion of the radiation component during the movement of the target. After 1000s, the curve of the target's reflected solar radiation drops linearly, indicating that the target enters the shadow area. Figure 7 is the proportion of the spatial omnidirectional radiation intensity of the target body and the background at t = 1s. Through the above steps, the precise modeling and simulation analysis of the infrared characteristics of the space target are realized.

[0106] Based on the algorithm of the present invention, the design of the user interface is carried out, such as Figure 8 、 Figure 9 as shown. Simulation environment: .

[0107] The above are only the embodiments of the present invention. Specific technical solutions and / or common knowledge such as characteristics well known in the art are not described in detail here. It should be noted that for those skilled in the art, without departing from the technical solution of the present invention, several deformations and improvements can still be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect and practicality of the present invention. The protection scope required by this application should be subject to the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. A calculation method for the radiation characteristics of the entire life cycle of a target, characterized in that It includes the following steps: S1. Target modeling and motion characteristic analysis: Construct a geometric model of the target, combine the orbit parameters and motion characteristics of the target, describe the motion trajectory and spatial position change of the target during its life cycle, and perform meshing on the outer surface of the target; S2. Temperature field analysis: Perform finite element analysis on the meshed model, calculate the temperature field, and predict the temperature distribution on the target surface; S3. Coordinate system transformation and projection area calculation: Convert the calculation results from the body coordinate system to the J2000 coordinate system, and further calculate the projection area of the target at different time points based on the geometric characteristics and motion trajectory of the target; S4. Perform radiation characteristic calculation during the entire life cycle of the target according to the temperature field, projection area of the target, and relevant data after coordinate system transformation: S401. First, determine whether the target is in the sunlit area or the shadow area; S402. If the target is located in the sunlit area, calculate the solar radiation view factor of the target surface element, calculate the radiance of the target surface element based on the solar irradiance and the solar radiation view factor, and then calculate the solar radiation intensity I absorbed by the target surface rs ; Let the normal vector of the target surface element be The radiation view factor between the target and the sun is: The sun is equivalent to a black body at 5900K, and its irradiance is: where λ is the wavelength, c1 is the first radiation constant, c2 is the second radiation constant, R S is the solar radius, and R SE is the mean distance between the sun and the earth; The radiance of the target surface element is: L i rs (λ, t) = α s β ts (t)E sun (λ, t) where α s is the absorptivity of the surface element to solar radiation; For the target surface element i, the solar radiation intensity reflected by the target surface at time t is: where A i is the area of this surface element, and R(t) is the rotation matrix of the target at time t is the normal vector of the target surface element i, and LOS is the normal vector of the detector detection direction is the cosine value of the angle between the normal vector of the target surface element and the normal vector of the detector detection, L i rs (λ,t) is the radiance of the surface element, and B is the set of surface elements in the detection field of view S403. Calculate the angular coefficient of the Earth's radiation. Based on the irradiance of the Earth and the angular coefficient of the Earth's radiation, calculate the amount of infrared radiation received by the surface element of the target surface, and then calculate the intensity I of the Earth's radiation reflected by the target surface. re ; Among them, the infrared irradiance of the earth is: where R e is the radius of the earth and h is the flying altitude of the target; The amount of terrestrial infrared radiation L received by the target surface element i re (λ, t) is: L i re (λ,t) = α e β te (t)E e (λ,t) where α e is the absorptivity of the surface element to the Earth's radiation; β te is the radiation view factor of the target reflecting the Earth's radiation, which is calculated by the angle between the normal vector of the surface element and the vector from the center of the Earth to the center of the surface element; The earth radiation intensity reflected by the target surface is: S404. If the target is located in the sunlit area, calculate the angular coefficient of the earth's reflected solar radiation, and then calculate the amount of the earth's reflected solar infrared radiation received by the surface element of the target based on the earth's albedo, solar irradiance, and the angular coefficient of the earth's reflected solar radiation, and further calculate the intensity I of the earth's reflected solar radiation reflected by the surface element of the target. res ; The calculation formula for the earth-reflected solar radiation view factor is as follows: Among them, φ is the angle between the line connecting the center of the earth and the centroid of the target surface element and the sun. When cosφ > 0, it indicates that the target flies in the sunlit area. When cosφ ≤ 0, it indicates that the target flies in the shadow area; The earth-reflected solar radiation intensity reflected by the target surface element is: where ρ E is the Earth albedo; S405. Calculate the self-thermal radiation of the target based on the self-radiation amount of the target The self-thermal radiation of the target is: where, ∈ is the infrared emissivity of the surface element, T i is the temperature of the target surface element i, is the radiance of the target surface element i at time t in the wavelength band λ1 to λ2; S406. Finally, calculate the total radiation intensity I of the target: I = I rs +I re +I res +I self 。 2. The radiation characteristic calculation method for a target full life cycle according to claim 1, wherein In step S2, by calculating the angle between the normal vector of the target surface element and the line of sight of the detector, it is determined whether each surface element is within the field of view of the detector. For all surface elements within the field of view of the detector, their projection areas are added together to obtain the overall projection area of the target surface.

3. The radiation characteristic calculation method for a target full life cycle according to claim 1, wherein, In step S5, let the position vector of the target be The solar unit radiation vector in the J2000 protocol coordinate system is Determine whether the target is in the shadow area: where R e is the radius of the Earth.

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