Space target infrared radiation characteristic prediction method and device and storage medium

Abstract

The invention discloses a prediction method and device for infrared radiation characteristics of a space target and a storage medium. According to the method, a correction term is introduced through a pseudo lumped parameter method, a differential equation suitable for the average surface temperature of most space targets is constructed, time-varying vectors in the equation can be calculated based on test or simulation data, and then a prediction model of the average surface temperature of the space targets is established. Subsequently, a computational waveband is selected and its radiation source is analyzed, an infrared radiation estimation model within the waveband is constructed, where reflected radiation can be acquired through test or simulation data. After a target infrared radiation prediction model is established, the infrared radiation intensity of the target under all-optical attributes can be rapidly predicted. The method is high in universality, prediction precision can meet most engineering requirements, prediction time consumption is extremely short, and computing resources can be greatly saved.

Description

Technical Field

[0001] The present invention relates to the field of infrared radiation characteristic calculation of space targets, and in particular to a method for quickly predicting the infrared radiation intensity of a space target during flight. Background Art

[0002] Space targets refer to objects operating in near-Earth space, primarily including space stations, orbiting satellites, and other spacecraft, as well as various types of space debris. With the rapid development of remote sensing, military weaponry, and other technologies, competition for space resources is intensifying, creating an urgent need to address the continuous tracking and accurate identification of space targets. Due to the low temperatures in space, space targets continuously emit energy. Therefore, the infrared radiation characteristics of a target are crucial parameters for identifying and determining its position, and are therefore of great practical significance for tracking and identifying space targets.

[0003] Due to the harsh environmental conditions in which space targets operate, it is difficult to obtain infrared radiation characteristic data for the entire target's lifespan. Furthermore, conducting experimental studies on the infrared radiation characteristics of space targets is costly, time-consuming, and challenging. To fully characterize the infrared radiation characteristics of space targets and evaluate infrared surveillance systems, modeling and simulating the detailed spectral infrared radiation characteristics of space targets is an effective approach. Currently, most simulation methods rely on the relative position of the space target to the Earth and the Sun. This is a transient problem that requires calculations at different time steps during flight, making it computationally cumbersome and time-consuming.

[0004] In order to balance adaptability to extreme space environments and functional reliability, the surface of space targets is usually covered with coating materials. Due to the large range of values ​​of the optical properties of coating materials (characterized by emissivity and absorptivity), the computing resources consumed by traditional methods have increased rapidly. Establishing a quantitative mapping relationship between them and the target's infrared radiation characteristics has become a core issue in the effective monitoring of space targets. Summary of the Invention

[0005] Technical problem: A method, device and storage medium for predicting the infrared radiation characteristics of space targets are proposed to quickly predict the infrared radiation intensity of space targets under different optical properties and achieve effective monitoring of space targets.

[0006] Technical solution:

[0007] The present invention first provides a method for predicting the infrared radiation characteristics of a space target, comprising the following steps:

[0008] Step 1: Construct the differential equation of the average surface temperature of the space target. The differential equation is shown in the following equation (1):

[0009]

[0010] Where, T represents the average temperature of the space target; τ represents time; α represents the absorptivity of the target surface coating; ε represents the emissivity of the target surface coating; Q in Represents the total radiation energy received by the target surface; Q out Represents the radiation energy emitted into space by a black body that is isothermal to the target; is a correction term related to the physical model and material; c represents the heat capacity of the target material, and m represents the mass of the target;

[0011] Formula (1) is processed to combine the total radiation energy received by the target surface, the radiation energy emitted by the target isothermal black body into space, the correction terms related to the physical model and material, the heat capacity of the target material and the mass of the target into a time-varying matrix P(τ), and simplify Formula (1) to Formula (2):

[0012]

[0013] Where P1(τ) and P2(τ) represent the temperature gradients caused by external heat input and self-heating during the flight of the target, respectively;

[0014] The Crank–Nicolson method is introduced to process Equation (2), as shown in Equation (3):

[0015]

[0016] Where, T n+1 and T n are the spatial targets τ n+1 time and τ n The average surface temperature corresponding to the time; τ n is a certain moment; τ n+1 is τ n The next time step of ; Δτ is the time step;

[0017] Step 2: Calculate or test two pieces of average surface temperature data with different optical properties of the current space target using the finite volume method;

[0018] Step 3: Based on the two average surface temperature data with different optical properties of the current space target obtained in step 2, solve P1(τ) and P2(τ) in equation (2) in step 1 to obtain the average temperature prediction model of the current target under the current trajectory;

[0019] Step 4: Select the calculation band and analyze the main radiation sources within the calculation band to obtain the infrared radiation estimation model within the calculation band;

[0020] Step 5: Obtain the infrared radiation intensity within the calculation band under a certain optical attribute of the current space target, and then calculate the environmental reflected radiation under the current target flight trajectory based on the infrared radiation estimation model constructed in step 4;

[0021] Step 6: Using the average temperature prediction model of the current target under the current trajectory obtained in step 3, the average temperature change of the target under arbitrary optical parameters is obtained; combined with the ambient reflected radiation obtained in step 5, a rapid prediction of the infrared radiation intensity within the calculation band is performed.

[0022] The present invention also provides a device for predicting infrared radiation characteristics of a space target, comprising:

[0023] one or more processors;

[0024] a memory for storing one or more programs;

[0025] When the one or more programs are executed by the one or more processors, the one or more processors implement the steps of the method for predicting infrared radiation characteristics of space targets provided above.

[0026] The present invention also provides a storage medium storing a computer program, which, when executed by a processor, implements the steps of the method for predicting the infrared radiation characteristics of a space target provided above.

[0027] Compared with the existing technology, the beneficial effects of the invention are:

[0028] 1. The present invention constructs a differential equation for the average surface temperature of a space target. When only a few calculation results or experimental results are obtained, the time-varying terms in the differential equation can be solved, thereby realizing the prediction of the surface average temperature corresponding to the entire domain of the target optical properties.

[0029] 2. The present invention constructs an estimation formula for the radiation intensity of space targets based on the calculation band, which can calculate the ambient radiation based on the infrared radiation intensity of the target under any optical parameters. Combined with the surface average temperature prediction model, it can realize the prediction of the target infrared radiation under different optical parameters.

[0030] 3. The calculation method proposed in this invention can meet the accuracy requirements of most projects, and the prediction time is extremely short, which can greatly save computing resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flow chart of the method for quickly predicting infrared radiation characteristics of space targets of the present invention.

[0032] Figure 2 The corresponding surface average temperature change diagram when the target emissivity is 0.2, the absorptivity is 0.8 and the target emissivity is 0.8, the absorptivity is 0.2

[0033] Figure 3 This is a comparison chart of the surface average temperature prediction results and the temperature calculation results of the traditional method.

[0034] Figure 4 yes Figure 3 Absolute error plot of temperature predictions.

[0035] Figure 5 This is a graph showing the change in average integrated radiation intensity on the target surface at medium waves (3-5μm) corresponding to a target emissivity of 0.5 and an absorptivity of 0.5.

[0036] Figure 6 This is the target long wave (8-14μm) surface average integrated radiation intensity change diagram corresponding to the target emissivity of 0.5 and the absorptivity of 0.5

[0037] Figure 7 This is a comparison chart between the medium-wave infrared radiation prediction results and the radiation calculation results of traditional methods.

[0038] Figure 8 This is a comparison chart between the long-wave infrared radiation prediction results and the radiation calculation results of the traditional method.

[0039] Figure 9 yes Figure 7 Relative error plot of mid-infrared radiation predictions.

[0040] Figure 10 yes Figure 8 Relative error plot of mid-infrared radiation predictions. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in combination with theoretical formulas and test results.

[0042] A fast prediction method for infrared radiation characteristics of space targets, such as Figure 1 As shown, the following steps are included:

[0043] Step 1: Construct a differential equation for the average surface temperature of a space target. The specific method is:

[0044] 1. Based on the pseudo-lumped parameter method, the differential equation of the average surface temperature of the space target is constructed. Since the thermal environment of the space target in the sunlit area and the shadow area is different, different differential equations need to be established according to the target location. This paper takes the sunlit area as an example. The differential equation of the sunlit area is shown in the following formula (1).

[0045]

[0046] Where, T represents the average temperature of the space target; τ represents time; α represents the absorptivity of the target surface coating; ε represents the emissivity of the target surface coating; Q inRepresents the total radiation energy received by the target surface (W / m 2 );Q out Represents the radiation energy emitted into space by a black body that is isothermal to the target (W / m 2 ); c represents the heat capacity of the target material, and m represents the mass of the target; This is a correction item, which is only related to the physical model and material.

[0047] 2. Simplify Equation (1) and combine the terms related to the target position, target physical model, and target material into a time-varying matrix P(τ), as shown in Equation (2).

[0048]

[0049] Where P1(τ) and P2(τ) represent the temperature gradients caused by external heat input and self-heating during the target's flight, respectively. P1(τ) and P2(τ) are related to the target's position and physical model.

[0050] Formula (2) is an explicit Euler formula, and the time accumulation phenomenon of the error is serious. In order to reduce the prediction error, the Crank–Nicolson method is introduced to process Formula (2), as shown in Formula (3).

[0051]

[0052] Where, T n+1 and T n are the spatial targets τ n+1 time and τ n The average surface temperature corresponding to the time; τ n is a certain moment; τ n+1 is τ n The next time step of ; Δτ is the time step;

[0053] Step 2: Calculate or test two pieces of average surface temperature data with different optical properties of the current space target using the finite volume method;

[0054] 1. The spatial target temperature data can be calculated using the traditional finite volume method. The control equation of the internal grid unit is shown in Equation (4). If it is a boundary node, an additional source term should be added. The calculation of the boundary conditions is shown in Equations (5)-(9).

[0055]

[0056] S add,i =q sun,i +q earth,i +q earthref,i -q self,i (5)

[0057]

[0058] Where S T is the source term (W / m 3 );S add,i The additional source term (W) added by applying boundary conditions to grid cell i; q sun,i ,q earth,i ,q earthref,i are the solar radiation heat absorbed by the boundary grid cell i, the earth radiation heat, and the earth reflected radiation heat (W); q self,i is the radiation energy emitted into space by the boundary grid cell i (W); S is the solar constant, which can be taken as 1353 (W / m 2 );θ i,j The angle between sunlight and the outer normal of the jth surface of the boundary grid cell i; ρ is the average albedo of the earth, which is 0.35; F ei,j 、F ri,j are the radiation angle coefficient between the j-th surface of the boundary grid cell i and the earth and the solar radiation angle coefficient reflected by the earth; σ is the Stefan-Boltzmann constant; T i 、T s are the temperatures of the boundary grid cell i and the space environment respectively; A i,j is the area of ​​the jth face of the boundary grid cell i (m 2 ).

[0059] The average temperature change data of the target flight time corresponding to the target emissivity of 0.2, the absorptivity of 0.8 and the emissivity of 0.8, the absorptivity of 0.2 are calculated, as shown in the following example: Figure 2 shown.

[0060] 2. Temperature test data can be obtained through multispectral temperature measurement. Multispectral temperature measurement uses an infrared detector to obtain the target infrared radiation intensity and measures the target temperature based on Planck's blackbody radiation formula.

[0061] Step 3: Solve the two time-varying vectors mentioned in step 1 based on the existing data in step 2 to obtain the average temperature prediction model of the current target under the current trajectory;

[0062] 1. Substitute the average temperature change data of the target flight time calculated in step 2 into equation (3) to form a linear equation system. By solving the equation system, P1(τ) and P2(τ) can be calculated, thereby completing the construction of the average temperature prediction model under the current flight trajectory of the current space target.

[0063] 2. In order to verify the accuracy of the model, the average surface temperature of the target under other optical properties is predicted, and the predicted results are compared with the results calculated by traditional methods. Figure 3 As shown, the corresponding absolute error is Figure 4 As shown in the figure, the maximum temperature deviation during the entire flight time is less than 1.5 K. These calculation results show that the temperature prediction model can meet most engineering requirements.

[0064] Step 4: Select the calculation band and analyze the main radiation sources within the calculation band to obtain the infrared radiation estimation model within the calculation band.

[0065] The mid-wave infrared (3-5 μm) and long-wave infrared (8-14 μm) bands are selected as the infrared radiation calculation bands. The main radiation from targets in the 3-5 μm band comes from solar radiation reflected by the target, solar radiation reflected by the earth, and spontaneous radiation. The radiation intensity estimation model in this band is shown in Equation (10). The main radiation from targets in the 8-14 μm band comes from spontaneous radiation and reflected earth radiation. The radiation intensity estimation model in this band is shown in Equation (11).

[0066] rad mid ≈rad self,mid +(1-α)(sun rad,mid +earthref rad,mid )(10)

[0067] rad long ≈rad self,long +(1-ε)earth rad,long (11)

[0068] Where rad mid and rad long Refers to the surface average integrated radiation intensity of space targets in medium wave (3-5μm) and long wave (8-14μm), rad self,mid and rad self,long Refers to the integral value of spontaneous radiation of space targets in medium wave and long wave, sun rad,mid Refers to the integral value of solar radiation reaching the surface of space target in the medium wave band, earthref rad,mid Refers to the integral value of the earth radiation reaching the surface of the space target in the medium wave band. rad,long Refers to the integral value of the earth's reflected radiation reaching the surface of the space target in the long-wave band.

[0069] Step 5: Calculate or test the infrared radiation intensity within the calculation band under a certain optical attribute of the current space target using traditional methods, and then calculate the ambient reflected radiation under the current target flight trajectory using the infrared radiation estimation model constructed in step 4;

[0070] 1. The spontaneous radiation intensity of the target can be calculated using Planck's law, as shown in formula (12).

[0071]

[0072] Where C1 and C2 are the first radiation constants (3.742×10 -16 W·m 2 ) and the second radiation constant (1.4388×10 -2 W·K); λ is the wavelength.

[0073] 2. The spectral reflected radiation intensity of the target can be calculated based on the relative position of the space target, the sun, and the earth, as shown in the following equations (13)-(15). By integrating within the corresponding calculation band, the medium-wave and long-wave radiation intensity series can be obtained.

[0074]

[0075] Where, E sun 、E earth 、E earthref They are the solar spectrum radiation intensity reflected by the target, the earth's spectrum radiation intensity, and the earth's reflected spectrum radiation intensity; E b,sun 、E b,earth are the spectral radiation intensities of the sun and the earth respectively; represents the i-th surface grid of the target; m represents the total number of target surface grids; θ i is the angle between the target surface i and the sunlight; ρ is the reflectivity of the earth, usually taken as 0.35; F ei is the radiation angle coefficient between the target surface i and the earth; F ri is the angular coefficient of solar radiation reflected by the Earth at surface i.

[0076] The surface average integrated radiation intensity of medium wave (3-5μm) and long wave (8-14μm) under the target flight time corresponding to the target emissivity of 0.5 and the absorptivity of 0.5 is calculated, as follows: Figure 5 、 Figure 6 shown.

[0077] The infrared radiation intensity of the target can also be obtained through experiments, usually by using an infrared camera mounted on a space-based detection platform or a ground-based detection platform to obtain the infrared radiation signal of the space target.

[0078] 3. After obtaining the radiation intensity sequence of the target under certain optical parameters, the environmental reflected radiation under the target flight trajectory can be calculated through the radiation intensity estimation model.

[0079] Step 6: Using the average temperature prediction model of the current target under the current trajectory obtained in step 3, the average temperature change of the target under arbitrary optical parameters is obtained. Combined with the ambient reflected radiation obtained in step 5, a rapid prediction of the infrared radiation intensity within the calculation band is performed.

[0080] At this point, the temperature prediction model and radiation intensity estimation model of the current space target under the current estimation have been solved. By inputting any optical parameters, the radiation intensity change data in the corresponding calculation band can be obtained. The prediction results are compared with the calculation results of the traditional method. Figure 7 、 Figure 8 The corresponding relative error is shown as Figure 9 、 Figure 10 As shown in the figure, during the entire flight cycle, the relative errors between the predicted results and the actual results in the two calculation bands are both within 2.5%, which can meet the vast majority of engineering requirements.

[0081] To test the computational speed of the proposed method, we selected three flight trajectories with a time step of 0.5 seconds and time steps of 1000, 2000, and 5000. The predicted time was recorded and compared with existing literature and traditional infrared radiation characteristic calculation methods. The test equipment used a 12th-generation Intel Core i5-12400F CPU and an NVIDIA GeForce RTX 4060 GPU.

[0082] Using the method described in this invention, the time required to solve the time-varying matrix in the temperature prediction model for the three flight trajectory groups was 0.278s, 1.041s, and 14.91s, respectively, and the time required for a single temperature prediction was 0.003s, 0.0024s, and 0.002s, respectively. The time required to solve the ambient reflected radiation in the infrared radiation estimation model was 0.47s, 0.938s, and 2.56s, respectively, and the time required for a single infrared radiation prediction was 0.476s, 0.931s, and 2.55s, respectively.

[0083] The temperature calculation speed was compared with Jiwei's GPU-accelerated real-time infrared simulation technology for high-speed flight targets. When the model grid number was 16029 and the flight trajectory time steps were 1000, 2000, and 5000, the corresponding temperature calculation times were 12.825s, 25.65s, and 51.3s, respectively, which is slower than the temperature prediction method of the present invention. The infrared radiation intensity calculation speed was compared with the traditional calculation method described in equations (13)–(15). When the model grid number was 16177, the calculation times corresponding to the three flight trajectory groups were 301.9s, 611.47s, and 2189.38s, respectively, which is significantly slower than the infrared radiation characteristic prediction method of the present invention.

[0084] Therefore, the present invention realizes the rapid calculation of the infrared radiation intensity of the space target surface coating under different optical parameters by constructing a space target temperature prediction model and a band-based infrared radiation estimation model, providing an effective evaluation benchmark for space target monitoring and tracking.

Claims

1. A method for predicting infrared radiation characteristics of a space target, characterized in that: The following steps are involved: Step 1: Construct the differential equation of the average surface temperature of the space target. The differential equation is shown in the following equation (1): Where, T represents the average temperature of the space target; τ represents time; α represents the target surface coating absorptivity; ε represents the emissivity of the target surface coating; Q in Represents the total radiation energy received by the target surface; Q out Represents the radiation energy emitted into space by a black body that is isothermal to the target; Corrections related to physical models and materials; c represents the heat capacity of the target material, and m represents the mass of the target; Formula (1) is processed to combine the total radiation energy received by the target surface, the radiation energy emitted by the target isothermal black body into space, the correction terms related to the physical model and material, the heat capacity of the target material and the mass of the target into a time-varying matrix P(τ), and simplify Formula (1) to Formula (2): Where P1(τ) and P2(τ) represent the temperature gradients caused by external heat input and self-heating during the flight of the target, respectively; The Crank–Nicolson method is introduced to process Equation (2), as shown in Equation (3): Where, T n+1 and T n are the spatial targets τ n+1 time and τ n The average surface temperature corresponding to the time; Δτ is the time step; τ n is a certain moment; τ n+1 is τ n The next time; Step 2: Obtain two pieces of average surface temperature data with different optical properties of the current space target; Step 3: Substitute the two average surface temperature data of the current space target with different optical properties obtained in step 2 into formula (3) in step 1, solve the time-varying matrix P(τ) in step 1, and thus obtain the average temperature prediction model of the current target under the current trajectory; Step 4: Select the calculation band and analyze the main radiation sources within the calculation band to obtain the infrared radiation estimation model within the calculation band; Step 5: Obtain the infrared radiation intensity within the calculation band under a certain optical attribute of the current space target, and then calculate the environmental reflected radiation under the current target flight trajectory based on the infrared radiation estimation model constructed in step 4; Step 6: Using the average temperature prediction model of the current target under the current trajectory obtained in step 3, the average temperature change of the target under arbitrary optical parameters is obtained; combined with the ambient reflected radiation obtained in step 5, a rapid prediction of the infrared radiation intensity within the calculation band is performed.

2. The method for predicting infrared radiation characteristics of a space target according to claim 1, characterized in that: In step 2, the finite volume method is used to calculate the temperature field of the target. The control equation of the internal grid unit is shown in equation (4), and the boundary conditions are calculated as shown in equations (5)-(9): S add,i =q sun,i +q earth,i +q earthref,i -q self,i (5) Where S T is the source term; S add,i The additional source term added by applying boundary conditions to grid cell i; q sun,i ,q earth,i ,q earthref,i are the solar radiation heat absorbed by the boundary grid cell i, the earth radiation heat, and the earth reflected radiation heat; q self,i is the radiation energy emitted into space by the boundary grid cell i; S is the solar constant; θ i,j The angle between sunlight and the outer normal of the jth surface of the boundary grid cell i; ρ is the average albedo of the earth; F ei,j 、F ri,j are the radiation angle coefficient between the j-th surface of the boundary grid cell i and the earth and the solar radiation angle coefficient reflected by the earth; σ is the Stefan-Boltzmann constant; T i 、T s are the temperatures of the boundary grid cell i and the space environment respectively; A i,j is the area of ​​the jth face of boundary grid cell i.

3. The method for predicting infrared radiation characteristics of a space target according to claim 1, characterized in that: In step 4, the selected calculation bands are the medium-wave infrared 3-5μm and the long-wave infrared 8-14μm; the radiation intensity estimation models of the target in the two bands are shown in equations (10) and (11) respectively: rad mid ≈rad self,mid +(1-α)(sun rad,mid +earthref rad,mid ) (10) rad long ≈rad self,long +(1-e)earth rad,long (11) Where, rad mid and rad long Refers to the surface average integrated radiation intensity of space targets in the medium-wave infrared 3-5μm and long-wave infrared 8-14μm, rad self,mid and rad self,long Refers to the integral value of spontaneous radiation of space targets in medium wave and long wave, sun rad,mid Refers to the integral value of solar radiation reaching the surface of space target in the medium wave band, earthref rad,mid Refers to the integral value of the earth radiation reaching the surface of the space target in the medium wave band. rad,long Refers to the integral value of the earth's reflected radiation reaching the surface of the space target in the long-wave band.

4. The method for predicting infrared radiation characteristics of a space target according to claim 1, wherein: In step 5, the infrared radiation intensity within the calculation band under a certain optical attribute of the current space target is obtained using the traditional method. The calculation formula for obtaining the infrared radiation intensity within the calculation band under a certain optical attribute of the current space target using the traditional method is shown in equations (12)-(15): Where, E sun 、E earth 、E earthref They are the solar spectrum radiation intensity reflected by the target, the earth's spectrum radiation intensity, and the earth's reflected spectrum radiation intensity; E b,sun 、E b,earth are the spectral radiation intensities of the sun and the earth respectively; i represents the target i-th surface mesh; m represents the total number of target surface meshes; θ i is the angle between the target surface i and the sunlight; ρ is the earth reflectivity; F ei is the radiation angle coefficient between the target surface i and the earth; F ri is the angular coefficient of solar radiation reflected by the Earth at surface i.

5. The method for predicting infrared radiation characteristics of a space target according to claim 1, characterized in that: In step 2, the method for obtaining two pieces of average surface temperature data with different optical properties of the current space target through experiments is: obtaining two pieces of average surface temperature data with different optical properties of the current space target through multi-spectral temperature measurement. Multi-spectral temperature measurement obtains the target infrared radiation intensity through an infrared detector and measures the target temperature based on Planck's blackbody radiation formula.

6. A device for predicting infrared radiation characteristics of a space target, characterized in that: include: one or more processors; a memory for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the steps of the method for predicting infrared radiation characteristics of a space target as described in any one of claims 1 to 5.

7. A storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method for predicting the infrared radiation characteristics of a space target as claimed in any one of claims 1 to 5 are implemented.

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