Method for calculating radiation characteristics of full life cycle of target

Abstract

The invention discloses a radiation characteristic calculation method for a full life cycle of a target, relates to the technical field of infrared signals, and aims to accurately simulate the radiation characteristic change of the target in the life cycle of the target. The method comprises the following steps: firstly, constructing a three-dimensional model of a target, and analyzing an orbit and motion characteristics of the three-dimensional model; secondly, the temperature field of the target is calculated through UG finite element analysis; then, converting a target coordinate system; secondly, calculating projection areas of the target at different time points; and finally, according to the data such as the temperature field and the projection area, calculating the full-life-cycle radiation characteristic of the target. Through the steps, the process that the target radiation characteristic changes along with time can be comprehensively and accurately described, and the method is suitable for the fields of spaceflight, aviation, military and the like and has important engineering application value.

Description

Technical Field

[0001] The invention relates to the field of infrared signal technology, and in particular to a method for simulating dynamic characteristics of infrared radiation based on the entire life cycle of a space target. Background Art

[0002] With the continuous advancement of aerospace technology, the complex motion state of space targets in orbit has 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 effects of the surrounding environment require accurate dynamic simulation. Existing infrared radiation simulation methods mainly focus on static or simplified models, lacking a comprehensive consideration of the changes in infrared radiation 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 stationary state, or only considering the change in radiation intensity at a certain point in time. Most of these methods ignore the micro-motion effects that may occur in the space target during orbital motion, resulting in insufficient accuracy in radiation calculation. Especially in complex orbits and non-uniform radiation environments, the existing methods cannot accurately simulate the changes in radiation intensity and radiation angle coefficient of the target surface micro-element at different time points. In addition, the existing simulation models usually do not fully consider the impact of multiple radiation sources such as solar radiation, earth reflected radiation, and deep space background radiation. They often use simplified assumptions and fail to fully consider the dynamic changes of the radiation source and the changes in the relative position of the space target surface. Due to the lack of consideration of these complex factors, the existing technology is difficult to meet the needs of high-precision infrared radiation characteristics analysis, especially when accurately simulating the radiation dynamic characteristics of the target in the space environment, the error is large and it is unable to provide sufficiently accurate data support.

[0004] In order to meet the high-precision requirements for the analysis of radiation characteristics of space targets, especially the dynamic simulation of radiation over the entire life cycle of targets 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 a simulation method for the dynamic characteristics of infrared radiation that can take into account the orbital motion, attitude changes, micro-motion effects and complex radiation environments of space targets over the entire life cycle has become a difficult problem that needs to be solved in the current technical field. Summary of the invention

[0005] The present invention provides a method for calculating the radiation characteristics of a target over its entire life cycle, which aims to accurately simulate the changes in the radiation characteristics of a target over its entire life cycle and has high application value.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: A method for calculating radiation characteristics of a target over its entire life cycle comprises the following steps: S1. Target modeling and motion characteristics analysis: Construct the geometric model of the target, combine the orbital parameters and motion characteristics of the target, describe the motion trajectory and spatial position changes of the target during its life cycle, and mesh 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 conversion 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. Calculate the radiation characteristics of the target throughout its life cycle based on the target’s temperature field, projection area, and related data after coordinate system conversion: S401, first determine whether the target is in a sunny area or a shadow area; S402: If the target is located in the sunlit area, calculate the solar radiation angle coefficient of the target surface element, calculate the radiance of the target surface element according to the solar irradiance and the solar radiation angle coefficient, and then calculate the solar radiation intensity absorbed by the target surface. ; S403, calculate the earth radiation angle coefficient, calculate the earth infrared radiation received by the target surface element according to the earth irradiance and the earth radiation angle coefficient, and then calculate the earth radiation intensity reflected by the target surface ; S404. If the target is located in the sunlit area, calculate the angle coefficient of solar radiation reflected by the earth, and then calculate the amount of solar infrared radiation reflected by the target surface element according to the earth reflectivity, solar irradiance and the angle coefficient of solar radiation reflected by the earth, and then calculate the intensity of solar radiation reflected by the target surface element. ; S405: Calculate the target's own thermal radiation according to the target's own radiation ; S406. Finally, calculate the total radiation intensity of the target :

[0007] Furthermore, by calculating the angle between the normal vector of the target face element and the line of sight of the detector, it is determined whether each face element is within the field of view of the detector. For all face elements in the field of view of the detector, their projection areas are added together to obtain the overall projection area of ​​the target surface.

[0008] Furthermore, 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:

[0009] in, is the radius of the Earth.

[0010] Furthermore, let the normal vector of the target surface element be , the radiation angle coefficient between the target and the sun is:

[0011] If the sun is equivalent to a 5900K black body, its irradiance is:

[0012] in, is the wavelength, is the first radiation constant, is the second radiation constant, is the radius of the sun, is the average distance between the Earth and the Sun; The radiance of the target pixel is:

[0013] in, is the absorption rate of solar radiation by the surface element; For the target surface , at the time The solar radiation intensity reflected by the target surface is:

[0014] in, For the area of ​​this bin, is the rotation matrix of the target at time t, is the target surface The normal vector of the detector, LOS is the normal vector of the detector detection direction, is the cosine value of the angle between the target surface element normal vector and the detector detection normal vector, is the radiance of the surface element, and B is the set of surface elements in the detection field of view.

[0015] Furthermore, in step S403, the infrared irradiance of the earth is:

[0016] in, is the radius of the earth, h is the flight altitude of the target; The amount of infrared radiation received by the target surface element for:

[0017] in, is the reflectivity of the surface element to the earth’s radiation; It is the radiation angle coefficient of the earth's radiation reflected by the target, which is calculated by the angle between the surface element normal vector and the vector from the center of the earth to the center of the surface element.

[0018] Furthermore, in step S404, the calculation formula of the angle coefficient of solar radiation reflected by the earth is as follows:

[0019] in, is the angle between the line connecting the center of the earth and the centroid of the target surface element and the sun. , indicating that the target is flying in the sunlight area. , indicating that the target is flying in the shadow area; The intensity of solar radiation reflected by the earth from the target surface is:

[0020] in, is the earth's reflectivity.

[0021] Further, in step S405, The target's own heat radiation is:

[0022]

[0023] in, is the infrared emissivity of the surface element, The target surface The temperature, is at time t, in the band , the radiance of target surface element i.

[0024] Compared with the prior art, the present invention has the following beneficial effects: 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.

[0025] 2. Strong adaptability: This method can adapt to the simulation needs of different types of space targets and can be applied to radiation calculations under various environmental conditions. It is widely used in aerospace, aviation, military and other fields.

[0026] 3. Comprehensiveness: Not only the traditional solar radiation and earth reflected radiation are taken into account, but also the micro-motion effect of the target is incorporated into the simulation to provide more complete radiation characteristic data and ensure accurate analysis in complex space environments.

[0027] 4. Strong data support: It provides reliable data support for the radiation management and control of the target, and can help engineering and technical personnel in related fields optimize the design and implementation plans. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A flowchart of a method for calculating radiation characteristics of a target throughout its life cycle; Figure 2 A schematic diagram of a target projection area of ​​a method for calculating radiation characteristics of a target over its entire life cycle; Figure 3 A schematic diagram of target surface element radiance of a method for calculating radiation characteristics of a target throughout its life cycle; Figure 4 A schematic diagram of target spectral radiation intensity of a method for calculating radiation characteristics of a target over its entire life cycle; Figure 5 A schematic diagram of target spectral radiance of a method for calculating radiation characteristics of a target over its entire life cycle; Figure 6 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; Figure 7 A schematic diagram of target omnidirectional radiation intensity of a method for calculating radiation characteristics of a target over its entire life cycle; Figure 8 It is a GUI input interface for the current full life cycle radiation characteristic calculation; Fig. 9 It is an output result interface for the current full life cycle radiation characteristics calculation. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments: like Figure 1 As shown, a method for calculating the radiation characteristics of a target over its entire life cycle includes the following steps: S1. Target modeling and motion characteristics analysis: First, an accurate geometric model of the target is constructed through 3D modeling technology. Combined with the target’s orbital parameters and motion characteristics, the target’s motion trajectory and spatial position changes during its life cycle are fully described.

[0030] Since the projected area of ​​the target in the detector's line of sight is usually smaller than its actual surface area, in order to more accurately describe the projected area of ​​the target, it is necessary to mesh the target's outer surface, usually using triangular micro-element segmentation. This process provides the basis for calculating the temperature distribution on the target's outer surface.

[0031] S2. Temperature field analysis: Secondly, use UG finite element analysis software 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 target surface can be accurately predicted.

[0032] S3, coordinate system conversion and projection area calculation: Convert the target coordinate system and convert the calculation results from the body coordinate system to the J2000 coordinate system. Based on the geometric characteristics and motion trajectory of the target, further calculate the projection area of ​​the target at different time points. Considering that there is relative motion between the target and the detector, and the target may be in a micro-motion state, it is necessary to determine whether each face element is within the field of view of the detector by calculating the angle between the normal vector of the target face element and the line of sight of the detector. For all face elements in the field of view of the detector, add up their projection areas to obtain the overall projection area of ​​the target surface.

[0033] S4. Calculation of radiation characteristics: Finally, based on the target’s temperature field, projection area, and related data after coordinate system conversion, the radiation characteristics of the target throughout its life cycle are calculated.

[0034] S401. First, determine whether the target is in the sunlit area. The sunlit area can receive solar radiation, while the shadow area cannot directly receive solar radiation. Therefore, it is necessary to determine whether the target is in the shadow area during flight in order to accurately calculate the amount of solar radiation absorbed and reflected by it. , let the target position vector be , the solar unit radiation vector in the J2000 protocol coordinate system is : Determine whether the target is in the shadow area:

[0035] Since the distance between the sun and the earth is much greater than the distance between the target and the center of the earth, the solar irradiance on the target surface can be approximated as the solar irradiance reaching the earth's surface.

[0036] S402, the infrared radiation illuminance of the sun at the target is , the solar radiation angle coefficient represents the proportion of solar radiation irradiating the target surface element, and the amount of solar radiation absorbed by the target surface is closely related to the angle coefficient. Suppose the normal vector of the target surface element is , the angle between the target and the sun is:

[0037] The sun is equivalent to a 5900K black body, and its irradiance is:

[0038] in, is the wavelength, is the first radiation constant, , is the second radiation constant, , is the radius of the sun, is the average distance between the Earth and the Sun; For the target pixel , at the time The solar radiation intensity reflected by the target surface is:

[0039]

[0040] in, is the reflectivity of the surface element to solar radiation, For the area of ​​this bin, is the radiance of the surface element, for The rotation matrix of the target at the moment, is the target surface The normal vector of the detector, LOS is the normal vector of the detector detection direction, is the cosine value of the angle between the target surface element normal vector and the detector detection normal vector, and B is the set of surface elements in the detection field of view.

[0041] S403, similar to the solar radiation angle coefficient, the earth radiation angle coefficient Indicates the projection ratio of the earth's radiation energy on the target surface element. The amount of infrared radiation received by the target surface element for:

[0042] in, is the reflectivity of the surface element to the earth’s radiation, The radiation angle coefficient of the target reflecting the earth's radiation can be calculated by the angle between the surface element normal vector and the vector from the center of the earth to the center of the surface element. is the infrared irradiance of the earth:

[0043] in, is the radius of the Earth , h is the flight altitude of the target.

[0044] The intensity of the earth radiation reflected by the target surface is:

[0045] S404, clouds, surface reflection and other factors, part of the solar radiation will be reflected, this part of the radiation is called earth reflected solar radiation, mainly concentrated in the visible light to short-wave infrared band. The earth reflected solar radiation angular coefficient represents the projection ratio of the reflected radiation energy on the target surface element, and its calculation formula is as follows:

[0046] in, is the angle between the line connecting the center of the earth and the centroid of the target surface element and the sun. , indicating that the target is flying in the sunlight area. , indicating that the target is flying in the shadow area.

[0047] The intensity of solar radiation reflected by the earth from the target surface is:

[0048] in, is the earth's reflectivity.

[0049] Since the moon and other stars are far away from space targets, the energy they radiate to the target surface is extremely weak and can be ignored; and the radiation from the deep space background can also be considered negligible due to its low temperature.

[0050] S405. The target's own heat radiation is:

[0051]

[0052] in, is the infrared emissivity of the surface element, is the temperature of target element i, For At the moment, in the band , the radiance of target surface element i.

[0053] S406. The total radiation intensity of the target is:

[0054] In this embodiment, the geometric characteristics of the target are first configured, a conical target is selected, and its orbital characteristics, attitude motion parameters, and flight altitude data are set; then the thermal physical characteristics of the target are defined, including surface emissivity, solar radiation absorptivity, and earth radiation absorptivity, and the target surface temperature distribution data is imported; at the same time, the space background radiation environment is set, including solar radiation, earth radiation, and the equivalent blackbody temperature of the deep space background; then the position vector and line of sight direction vector of the detector are input to establish the relative geometric relationship between the detector and the target; finally, the detection band is set to 3-5 The medium-wave infrared range completes the parameter configuration of the entire simulation system.

[0055] Then calculate the projected area of ​​the target under the detector field of view, such as Figure 2 As shown, the target is The projected area at this time is 0.31207 square meters, which is located in the sun-irradiated area and is directly affected by solar radiation. After obtaining the target projected area, the radiation characteristics can be further calculated. Figure 3 For the target surface The radiance curve, with the horizontal axis being the number of facets and the vertical axis being the radiance, plots five curves: the target's own thermal radiation, reflected solar radiation, reflected solar radiation reflected by the earth, reflected earth radiation, and total radiation. Figure 4 is the target spectral radiation intensity, indicating the intensity at different times Target spectral radiation intensity curve. Figure 5 For facet The average radiance of the band, Figure 6 This is the curve of the radiation component proportion during the target's movement. After 1000s, the target's reflected solar radiation curve drops sharply, indicating that the target has entered the shadow area. Figure 7 is the ratio of the spatial omnidirectional radiation intensity of the target body and the background at t=1s. Through the above steps, accurate modeling and simulation analysis of the infrared characteristics of space targets are achieved.

[0056] Based on the algorithm of the present invention, a user interaction interface is designed, such as Figure 8 , Fig. 9 As shown. Simulation environment: .

[0057] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect and practicality of the implementation of the present invention. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for calculating the radiation characteristics of a target over its entire life cycle, characterized in that: The steps include: S1. Target modeling and motion characteristics analysis: Construct the geometric model of the target, combine the orbital parameters and motion characteristics of the target, describe the motion trajectory and spatial position changes of the target during its life cycle, and mesh 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 conversion 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. Calculate the radiation characteristics of the target throughout its life cycle based on the target’s temperature field, projection area, and related data after coordinate system conversion: S401, first determine whether the target is in a sunny area or a shadow area; S402: If the target is located in the sunlit area, calculate the solar radiation angle coefficient of the target surface element, calculate the radiance of the target surface element according to the solar irradiance and the solar radiation angle coefficient, and then calculate the solar radiation intensity absorbed by the target surface. ; S403, calculate the earth radiation angle coefficient, calculate the earth infrared radiation received by the target surface element according to the earth irradiance and the earth radiation angle coefficient, and then calculate the earth radiation intensity reflected by the target surface ; S404. If the target is located in the sunlit area, calculate the angle coefficient of solar radiation reflected by the earth, and then calculate the amount of solar infrared radiation reflected by the target surface element according to the earth reflectivity, solar irradiance and the angle coefficient of solar radiation reflected by the earth, and then calculate the intensity of solar radiation reflected by the target surface element. ; S405: Calculate the target's own thermal radiation according to the target's own radiation ; S406. Finally, calculate the total radiation intensity of the target : 。 2. The method for calculating the radiation characteristics of a target during its entire life cycle according to claim 1, characterized in that: In step S2, by calculating the angle between the normal vector of the target surface element and the detector line of sight, it is determined whether each surface element is within the field of view of the detector. For all surface elements in 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 method for calculating the radiation characteristics of a target during its entire life cycle according to claim 1, characterized in that: In step S5, the position vector of the target is assumed to be , the solar unit radiation vector in the J2000 protocol coordinate system is , determine whether the target is in the shadow area: ； in, is the radius of the Earth.

4. The method for calculating the radiation characteristics of a target during its entire life cycle according to claim 1, characterized in that: In step S402, the normal vector of the target surface element is assumed to be , the radiation angle coefficient between the target and the sun is: ； If the sun is equivalent to a 5900K black body, its irradiance is: ； in, is the wavelength, is the first radiation constant, is the second radiation constant, is the radius of the sun, is the average distance between the Earth and the Sun; The radiance of the target pixel is: ； in, is the absorption rate of solar radiation by the surface element; For the target surface , the solar radiation intensity reflected by the target surface at time t is: ； in, For the area of ​​this bin, for The rotation matrix of the target at the moment, is the target surface The normal vector of the detector, LOS is the normal vector of the detector detection direction, is the cosine value of the angle between the target surface element normal vector and the detector detection normal vector, is the radiance of the surface element, and B is the set of surface elements in the detection field of view.

5. The method for calculating the radiation characteristics of a target during its entire life cycle according to claim 1, characterized in that: In step S403, the infrared irradiance of the earth is: ； in, is the radius of the earth, h is the flight altitude of the target; The amount of infrared radiation received by the target surface element for; ； in, is the absorption rate of the surface element to the earth's radiation; is the radiation angle coefficient of the earth radiation reflected by the target, 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 intensity of the earth radiation reflected by the target surface is: 。 6. The method for calculating the radiation characteristics of a target during its entire life cycle according to claim 1, characterized in that: In step S404, the calculation formula of the solar radiation angular coefficient reflected by the earth is as follows: ； in, is the angle between the line connecting the center of the earth and the centroid of the target surface element and the sun. , indicating that the target is flying in the sunlight area. , indicating that the target is flying in the shadow area; The intensity of solar radiation reflected by the earth from the target surface is: ； in, is the earth's reflectivity.

7. The method for calculating radiation characteristics of a target during its entire life cycle according to claim 1, characterized in that: In step S405, The target's own heat radiation is: ； ； in, is the infrared emissivity of the surface element, The target surface The temperature, is at time t, in the band , the radiance of target surface element i.

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