Star sensor full-link imaging modeling method and device under high-speed aerodynamic environment

Abstract

The application provides a star sensor full-link imaging modeling method and device in a high-speed aerodynamic environment. The method comprises the following steps: acquiring starlight emitted by all far-field stars in an observation scene by using a star sensor camera, and obtaining a first light direction of an incident star and a first radiant intensity of the incident star by using the starlight; performing atmospheric transmission modeling processing on the first radiant intensity of the incident star based on an atmospheric radiation transmission calculation model to obtain a second radiant intensity of the incident star; performing aerodynamic optical transmission modeling processing on the first light direction of the incident star and the second radiant intensity of the incident star respectively, and correspondingly obtaining a second light direction of the incident star and a third radiant intensity of the incident star; and performing star sensor transmission modeling processing based on an atmospheric turbulence dynamic imaging blur model, the second light direction of the incident star and the third radiant intensity of the incident star to obtain a gray-scale imaging result. Therefore, the influence of aerodynamic optical effects on the performance of the star sensor can be more accurately evaluated.

Description

Technical Field

[0001] This invention relates to the field of high-speed flow field star image imaging technology, specifically to a method and apparatus for full-link imaging modeling of star sensors under high-speed aerodynamic environments. Background Technology

[0002] When hypersonic vehicles travel at high speeds in near-space, their interaction with incoming currents generates complex flow field structures, such as boundary layers and shock layers, which induce thermal responses in optical windows, leading to aero-optical effects that interfere with optical transmission. As high-precision navigation devices, the imaging quality of star sensors directly affects navigation accuracy. However, aero-optical effects can cause offsets, blurring, and jitter in star imagery, severely impacting detection capabilities and measurement accuracy. With increasing demands from near-space vehicles, the accuracy requirements for star sensor imaging simulation are rising. However, current research largely focuses on the coupled analysis of the light field and the flow medium, lacking a systematic exploration of the complete imaging chain from the stellar target, transmission medium, optical system to sensor. Furthermore, existing partial research results are difficult to effectively integrate into the entire chain, hindering further improvements in star sensor imaging simulation and navigation accuracy under high-speed flow fields.

[0003] In existing technologies, studies have attempted to model and evaluate the impact of aero-optical effects in high-speed flow fields from the perspective of local factors. For example, in 2025, Xiangjun Zhang, Liang Xu, and others proposed a fluid-structure interaction model based on a blunt-nosed double-cone side-window aircraft. Using an air-to-air missile as a case study, they quantitatively evaluated the imaging performance of the optical system from three dimensions: light deflection, wavefront transmission distortion, and imaging bias through computational fluid dynamics numerical simulation combined with a reverse ray tracing algorithm. This approach focuses on the coupling effect between the flow field and optical transmission, providing a reference for the analysis of local effects in aero-optics.

[0004] Nevertheless, existing technologies still have significant limitations. On the one hand, most related studies are limited to the interaction between the light field and the medium, failing to realize the complete signal link from the target, transmission medium, optical system to the sensor, resulting in insufficient integrity in imaging simulations. On the other hand, local research results are often difficult to effectively integrate with the entire link, and research on the full-link imaging simulation of star sensors under high-speed flow fields is relatively lacking, hindering the development of high-precision star map simulation and navigation algorithms. Therefore, there is an urgent need for an imaging method that can systematically integrate all elements of the entire link to more accurately assess the impact of aero-optical effects on star sensor performance. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a method and apparatus for full-link imaging modeling of star sensors under high-speed aerodynamic environments.

[0006] The technical problem to be solved by this invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for full-link imaging modeling of star sensors under high-speed aerodynamic conditions, comprising: The starlight emitted by all distant stars in the observation scene is acquired using a star sensor camera, and the starlight is used to model the stellar background to obtain the first ray direction and the first irradiance of the incident star. Based on the atmospheric radiative transfer calculation model, and using the first irradiance of the incident star for atmospheric transfer modeling, the second irradiance of the incident star with atmospheric transfer effect is obtained. A dynamic imaging blur model of atmospheric turbulence was constructed using Gaussian random functions and Kolmogorov turbulence theory. Aerodynamic optical transmission modeling was performed on the first ray direction and the second irradiance of the incident star, respectively, to obtain the second ray direction and the third irradiance of the incident star with added aerodynamic optical effects. Star sensor transmission modeling is performed based on atmospheric turbulence dynamic imaging fuzzy model, the direction of the second ray of the incident star and the third irradiance of the incident star to obtain the star sensor voltage signal; The star sensor voltage signal is quantized by an ADC to obtain a grayscale imaging result.

[0007] Optionally, the second irradiance of the incident star is expressed as: ; in, This represents the second irradiance of the incident star. Indicates the first irradiance of the incident star. This represents the atmospheric transmittance calculated based on the MODTRAN atmospheric radiative transfer model. This represents the path radiation calculated based on the MODTRAN atmospheric radiative transfer model.

[0008] Optionally, the dynamic imaging fuzzy model of atmospheric turbulence is represented as: ; in, This represents a dynamic imaging blur model of atmospheric turbulence. Table of turbulence modulation transfer function, Represents the turbulent random modulation transfer function; ; ; ; ; ; in, Indicates spatial frequency, For space wavenumber, The refractive index is the structural constant. It is a Gaussian random function with a mean of 0 and a variance of 1, and has Hermitian symmetry; The power spectrum function representing atmospheric turbulence. Indicates the wavelength of starlight. This represents the correction factor for the finite aperture smoothing effect. This indicates the diameter of the receiving aperture of the star sensor camera in the star sensor system. This indicates the height of the star sensor camera.

[0009] Optionally, aerodynamic optical transmission modeling is performed on the first ray direction and the second irradiance of the incident star, respectively, to obtain the second ray direction and the third irradiance of the incident star with added aerodynamic optical effects, including: The refractive index field of the external flow field region was calculated based on the Gladstone-Dale expression. Based on the thermo-optical and elasto-optical effects corresponding to the optical window of the star sensor system, the refractive index field inside the optical window of the star sensor system is calculated. Based on the light transmission equation and Snell's law, the refractive index field of the outer flow field region and the refractive index field inside the optical window are used to transmit the direction of the first ray of the incident star sequentially in the outer flow field, the interface between the outer flow field and the optical window, and inside the optical window to obtain the direction of the second ray of the incident star. Based on Fresnel's law, the second irradiance of the incident star is transmitted at the interface of the optical window to obtain the third irradiance of the incident star.

[0010] Optionally, star sensor transmission modeling is performed based on the atmospheric turbulence dynamic imaging blur model, the direction of the second ray from the incident star, and the third irradiance of the incident star to obtain the star sensor voltage signal, including: The image plane conversion of the second ray direction of the incident star is performed by the star sensor camera to obtain the image plane pixel position corresponding to the incident star. The initial voltage signal of the star sensor in the star sensor system is calculated based on the third irradiance of the incident star. The spatial transfer functions of the optical system, the detector, and the signal processing circuit are calculated separately. Then, the spatial transfer functions of the optical system, the detector, and the signal processing circuit are multiplied by the atmospheric turbulence dynamic imaging fuzzy model to obtain the final spatial transfer function. The noise of the star sensor system is obtained by combining the background noise, shot noise, and dark current noise in the detector noise. The star sensor voltage signal at the image pixel location is calculated using the initial voltage signal of the star sensor, the star sensor system noise, and the final spatial transfer function.

[0011] Optionally, the initial voltage signal of the star sensor is represented as: ; ; in, This represents the value of the initial voltage signal of the star sensor. For detector gain, To be at starlight wavelength Lower detector responsivity, This represents the radiant flux from the star reaching the detector's pixels. The photosensitive area of ​​the detector pixel. For the transmittance of the optical system, This refers to the aperture number of the optical system. Indicates the third irradiance of the incident star. This indicates the lower limit of the integral of the detector's spectral response. This indicates the upper limit of the detector's spectral response integral.

[0012] Optionally, the noise of the star sensor system is expressed as: ; in, This represents the noise value of the star sensor system. This represents the conversion gain coefficient of the star sensor system. The number of photoelectrons produced by the target radiation. This indicates the number of photoelectrons generated by the detector in response to background noise. This represents the number of photoelectrons produced by the dark current.

[0013] Optionally, the grayscale imaging result is represented as: ; in, This indicates the grayscale imaging result. This represents the star sensor voltage signal. This indicates the upper limit of the saturation voltage of the ADC. This indicates the number of quantization bits in the ADC.

[0014] In a second aspect, the present invention provides a star sensor full-link imaging modeling device under high-speed aerodynamic environment, which includes: a star background modeling unit, an atmospheric transmission modeling unit, an atmospheric turbulence dynamic imaging modeling unit, an aero-optical transmission modeling unit, a star sensor transmission modeling unit, and an ADC quantization unit. The stellar background modeling unit is used to acquire starlight emitted by all distant stars in the observation scene using a star sensor camera, and to perform stellar background modeling processing using starlight to obtain the first ray direction and the first irradiance of the incident star. The atmospheric transport modeling unit is used to perform atmospheric transport modeling based on the atmospheric radiative transport calculation model and to obtain the second radiative transport of the incident star with atmospheric transport effects added. The atmospheric turbulence dynamic imaging modeling unit is used to construct a blurred model of atmospheric turbulence dynamic imaging using Gaussian random functions and Kolmogorov turbulence theory. The aero-optical transmission modeling unit is used to perform aero-optical transmission modeling on the first ray direction and the second irradiance of the incident star, respectively, and obtains the second ray direction and the third irradiance of the incident star with aero-optical effects added. The star sensor transmission modeling unit is used to perform star sensor transmission modeling based on the atmospheric turbulence dynamic imaging blur model, the direction of the second ray of the incident star and the third irradiance of the incident star, and to obtain the star sensor voltage signal. The ADC quantization unit is used to quantize the star sensor voltage signal to obtain grayscale imaging results.

[0015] Thirdly, the present invention provides a star sensor full-link imaging modeling device under high-speed aerodynamic environment, comprising: a processor, a storage medium and a bus, wherein the storage medium stores machine-readable instructions executable by the processor. When the star sensor full-link imaging modeling device under high-speed aerodynamic environment is running, the processor communicates with the storage medium through the bus, and the processor executes the machine-readable instructions to perform the steps of the star sensor full-link imaging modeling method under high-speed aerodynamic environment as described in the first aspect above.

[0016] This invention provides a method and apparatus for full-link imaging modeling of a star sensor under high-speed aerodynamic conditions. The method includes: acquiring starlight emitted by all distant stars in the observation scene using a star sensor camera, and performing stellar background modeling processing using the starlight to obtain the first ray direction and first radiance of the incident star; performing atmospheric transmission modeling processing based on an atmospheric radiative transfer calculation model, and using the first radiance of the incident star to obtain a second radiance of the incident star with added atmospheric transmission effects; constructing an atmospheric turbulence dynamic imaging blur model using Gaussian random functions and Kolmogorov turbulence theory; performing aerodynamic optical transmission modeling processing on the first ray direction and second radiance of the incident star respectively, to obtain the second ray direction and third radiance of the incident star with added aerodynamic optical effects; performing star sensor transmission modeling processing based on the atmospheric turbulence dynamic imaging blur model, the second ray direction, and the third radiance of the incident star to obtain a star sensor voltage signal; and performing ADC quantization processing on the star sensor voltage signal to obtain a grayscale imaging result. This invention first addresses the lack of completeness in existing imaging simulations by constructing a complete signal chain from stars, atmospheric transmission, turbulence, aero-optics, optical systems, to sensors. Then, by sequentially cascading stellar background modeling, atmospheric transmission modeling, atmospheric turbulence dynamic imaging fuzzy modeling, aero-optical transmission modeling, star sensor transmission modeling, and ADC quantization processing, effective fusion of local models is achieved, resolving the difficulty of integrating local research results with the entire chain. In particular, this invention specifically introduces aero-optical transmission modeling for high-speed aerodynamic environments, addressing the lack of comprehensive imaging simulation research under high-speed flow fields. Finally, through comprehensive modeling, more realistic star sensor voltage signals and grayscale imaging results are obtained, enabling a more accurate assessment of the impact of aero-optical effects on star sensor performance, thus providing an effective simulation tool for the development of high-precision star map simulation and navigation algorithms.

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 A flowchart illustrating a full-link imaging modeling method for star sensors in a high-speed aerodynamic environment, provided by an embodiment of the present invention; Figure 2 An execution block diagram of a star sensor full-link imaging modeling method under high-speed aerodynamic environment is shown as an example; Figure 3 This is a schematic diagram of the structure of a star sensor full-link imaging modeling device under high-speed aerodynamic environment provided in an embodiment of the present invention; Figure 4This is a schematic diagram of the structure of a star sensor full-link imaging modeling device under high-speed aerodynamic environment provided in an embodiment of the present invention. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0020] In order to more accurately evaluate the impact of aero-optical effects on the performance of star sensors, and thus provide an effective simulation tool for the development of high-precision star map simulation and navigation algorithms, this invention provides a method for full-link imaging modeling of star sensors under high-speed aerodynamic environments. Figure 1 This is a flowchart illustrating a full-link imaging modeling method for star sensors under high-speed aerodynamic conditions, as provided in an embodiment of the present invention. Figure 1 As shown, it includes: S101. Use a star sensor camera to acquire starlight emitted by all distant stars in the observation scene, and use the starlight to perform stellar background modeling to obtain the direction of the first ray of the incident star and the first irradiance of the incident star.

[0021] In this embodiment, the right ascension and declination information of stars can be extracted from the star catalog based on the orientation information of the star sensor camera contained in the starlight. And it can be transformed into a ray vector in an inertial frame by the following formula. : ; The attitude of the spacecraft equipped with a star sensor The `eul2rotm` function in the "RoboticsSystem Toolbox" of MATLAB can be used to obtain the rotation matrices of the inertial frame around the Z, Y, and X axes to the star sensor coordinate system. : ; From this, we can obtain the direction of the ray from the incident star to the star sensor coordinate system, that is, the direction of the first ray from the incident star. : ; The relationship between a star's brightness and its magnitude is expressed by the following expression: ; In the formula , These are the apparent magnitudes of the two incident stars, respectively. , These are the illumination values ​​of the two stars on the detector's surface, respectively.

[0022] Visible light band Below, the irradiance of sporadic stars outside the atmosphere is [value missing]. .by As a benchmark for calculating illuminance, the following expression can be obtained by combining the relationship between stellar brightness and magnitude: The irradiance of a star, i.e., the first irradiance of the incident star. .

[0023] S102. Based on the atmospheric radiative transfer calculation model, and using the first radiative illuminance of the incident star for atmospheric transfer modeling, the second radiative illuminance of the incident star with atmospheric transfer effect is obtained.

[0024] Modeling of atmospheric transport mainly focuses on two aspects: 1) radiative attenuation and path radiation caused by atmospheric transport; 2) imaging blurring caused by atmospheric turbulence. The direction of the first ray incident on the star was obtained from the stellar background modeling. and the first irradiance of the incident star Afterwards, it needs to undergo radiation attenuation through atmospheric transmission and be superimposed with path radiation.

[0025] In this invention, the radiative attenuation and path radiation caused by atmospheric transmission are obtained using MODTRAN. Using MODTRAN with altitude and zenith angle as input, atmospheric transmittance and path radiation information at different altitudes and zenith angles are obtained. The zenith angle refers to the angle between the direction of sunlight pointing towards the spacecraft carrying the star sensor and the direction from the Earth's center towards the spacecraft. The illuminance after atmospheric transmission, i.e., the second radiative illuminance of the incident star, can then be obtained. as follows: Optionally, the second irradiance of the incident star is expressed as: ; in, This represents the second irradiance of the incident star. Indicates the first irradiance of the incident star. This represents the atmospheric transmittance calculated based on the MODTRAN atmospheric radiative transfer model. This represents the path radiation calculated based on the MODTRAN atmospheric radiative transfer model.

[0026] S103. A dynamic imaging blur model of atmospheric turbulence is constructed using Gaussian random functions and Kolmogorov turbulence theory.

[0027] Optionally, the dynamic imaging fuzzy model of atmospheric turbulence is represented as: ; in, This represents a dynamic imaging blur model of atmospheric turbulence. Table of turbulence modulation transfer function, Represents the turbulent random modulation transfer function; ; ; ; ; ; in, Indicates spatial frequency, For space wavenumber, The refractive index is the structural constant. It is a Gaussian random function with a mean of 0 and a variance of 1, and has Hermitian symmetry; The power spectrum function representing atmospheric turbulence. Indicates the wavelength of starlight. This represents the correction factor for the finite aperture smoothing effect. This indicates the diameter of the receiving aperture of the star sensor camera in the star sensor system. This indicates the height of the star sensor camera.

[0028] S104. Aerodynamic optical transmission modeling was performed on the first ray direction and the second irradiance of the incident star, respectively, to obtain the second ray direction and the third irradiance of the incident star with added aerodynamic optical effects.

[0029] Optionally, S104 specifically includes: The refractive index field of the external flow field region was calculated based on the Gladstone-Dale expression. Based on the thermo-optical and elasto-optical effects corresponding to the optical window of the star sensor system, the refractive index field inside the optical window of the star sensor system is calculated. Based on the light transmission equation and Snell's law, the refractive index field of the outer flow field region and the refractive index field inside the optical window are used to transmit the direction of the first ray of the incident star sequentially in the outer flow field, the interface between the outer flow field and the optical window, and inside the optical window to obtain the direction of the second ray of the incident star. Based on Fresnel's law, the second irradiance of the incident star is transmitted at the interface of the optical window to obtain the third irradiance of the incident star.

[0030] Specifically, aero-optical effects mainly occur within the optical window of the star sensor optical system and in the flow field outside the optical window. In this invention, the aero-optical effect is modeled by first modeling the refractive index changes inside the optical window and in the flow field region where the aero-optical effect occurs, and then by modeling the refractive index changes during light transmission. and Calculations are performed to obtain the geometric deflection and energy change of light rays after aero-optical effects, thus obtaining the new direction and irradiance of starlight.

[0031] By using CFD simulation of multiphysics, we can obtain flow density field data, temperature field data of optical window, and stress-strain field data. Based on these data, we first construct the flow field region and the refractive index field within the optical window.

[0032] Refractive index field of the flow field region It can be calculated using the Gladstone-Dale relation and gas density, and the formula can be expressed as: ; In the formula, For flow field density, For wavelength, is the refractive index.

[0033] Refractive index field within the optical window The construction of the refractive index field inside the optical window material is mainly affected by the thermo-optical effect and the elasto-optical effect of its medium material.

[0034] The relationship with temperature can be expressed by the thermo-optical effect as follows: ; In the formula, This indicates that the wavelength of the light is And the medium is in a spatial position Corresponding temperature The magnitude of the refractive index of the medium at that time; It is the temperature of the medium material during the simulation; This refers to the thermo-optic coefficient of the corresponding medium material; Indicates that at a temperature of The wavelength of the light is The refractive index value of the medium at that time.

[0035] The relationship between stress and strain can be expressed by the elasto-optic effect as follows: Temperature-corrected refractive index Building upon this foundation, the anisotropy of refractive index caused by stress field is further introduced. This invention utilizes a sapphire crystal optical window, based on the elasto-optical effect theory, considering the strain field generated by thermal stress and aerodynamic pressure. The final refractive index distribution can be expressed as: ; In the formula, For any position inside the optical window calculated based on the thermo-optical effect and the elasto-optical effect refractive index, Let be the tensor component of the optical elastic coefficient of the optical window material. The strain field components are obtained from CFD fluid-structure interaction simulation.

[0036] Light transmission and energy calculation: Obtaining the refractive index of the external flow field Refractive index inside the optical window After that, it is necessary to... The propagation process within the external flow field and the optical window is calculated. The entire process is divided into: propagation in the external flow field medium, calculation at the interface between the external flow field and the optical window, propagation within the optical window, and light emission.

[0037] The direction of the first ray of the incident star can be transmitted sequentially in the outer flow field and inside the optical window by combining the ray equation with the refractive index field within the optical window.

[0038] The calculation of the interface between the external flow field and the optical window uses the calculated flow field refractive index. The refractive index of medium 1 is calculated using the thermo-optical effect and the elasto-optical effect to determine the refractive index inside the non-homogeneous medium. As the refractive index of medium 2, Snell's law is used. Calculate the direction of light transmission.

[0039] The calculation of the propagation process between the external flow field and the optical window includes, based on Fresnel's law, the transmission of the second irradiance of the incident star at the interface of the optical window to obtain the third irradiance of the incident star.

[0040] Ultimately, the direction of the input starlight With irradiance After propagation in the outer flow field, calculation of the interface between the outer flow field and the outer surface of the window, and propagation inside the optical window, the final direction of the light ray with added aero-optical effects (the direction of the second ray of the incident star) is obtained. And energy (third irradiance of the incident star) : S105. Based on the atmospheric turbulence dynamic imaging fuzzy model, the direction of the second ray of the incident star and the third irradiance of the incident star, the star sensor transmission modeling is performed to obtain the star sensor voltage signal.

[0041] Optionally, S105 may specifically include: The image plane conversion of the second ray direction of the incident star is performed by the star sensor camera to obtain the image plane pixel position corresponding to the incident star. The initial voltage signal of the star sensor in the star sensor system is calculated based on the third irradiance of the incident star. The spatial transfer functions of the optical system, the detector, and the signal processing circuit are calculated separately. Then, the spatial transfer functions of the optical system, the detector, and the signal processing circuit are multiplied by the atmospheric turbulence dynamic imaging fuzzy model to obtain the final spatial transfer function. The noise of the star sensor system is obtained by combining the background noise, shot noise, and dark current noise in the detector noise. The star sensor voltage signal at the image pixel location is calculated using the initial voltage signal of the star sensor, the star sensor system noise, and the final spatial transfer function.

[0042] It should be noted that the optical system in the embodiments of the present invention can be the system in which the star-sensitive camera lens is located.

[0043] Optionally, the initial voltage signal of the star sensor is represented as: ; ; in, This represents the value of the initial voltage signal of the star sensor. For detector gain, To be at starlight wavelength Lower detector responsivity, This represents the radiant flux from the star reaching the detector's pixels. The photosensitive area of ​​the detector pixel. For the transmittance of the optical system, This refers to the aperture number of the optical system. Indicates the third irradiance of the incident star. This indicates the lower limit of the integral of the detector's spectral response. This indicates the upper limit of the detector's spectral response integral.

[0044] Optionally, the noise of the star sensor system is expressed as: ; in, This represents the noise value of the star sensor system. This represents the conversion gain coefficient of the star sensor system. The number of photoelectrons produced by the target radiation. This indicates the number of photoelectrons generated by the detector in response to background noise. This represents the number of photoelectrons produced by the dark current.

[0045] The execution process of S105 is described in detail below: Then, the light enters the ideal optical system and falls onto the image plane of the star sensor camera. The coordinate relationship is transformed as follows: ; ( , () indicates the pixel position on the image plane corresponding to the incident star. For the focal length of an ideal optical system, , For column cell size and row cell size.

[0046] Star sensor initial voltage signal Represented as: ; ; For the gain of the detector system, The detector responsivity of the detector unit. This represents the radiant flux from the star reaching the detector's pixels. The photosensitive area of ​​the detector pixel. For the transmittance of the optical system, This refers to the aperture number of the optical system.

[0047] Space transfer function calculate: In this invention, for The calculation for the optical system ,detector Signal processing circuit Blur model of dynamic imaging of atmospheric turbulence The composite of.

[0048] Optical system Optical system The main considerations are the effects of diffraction and aberration.

[0049] For a diameter of Circular aperture, diffraction The calculation formula is: ; In the formula, The spatial cutoff frequency of an incoherent imaging system. The average wavelength of the spectral band. , These represent the spatial frequencies in the horizontal and vertical directions, respectively.

[0050] aberration The calculation formula is: ; In the formula, For standard deviation, , It is 1 / 4 of the diameter of the circle of confusion.

[0051] The overall optical system transfer function is : ; detector The calculations include: For staring imaging systems, detector spatial filtering is mainly determined by spatial integration. For a rectangular detector, its detector MTF can be expressed as: ; In the formula, , Let be the first spatial angle and the second spatial angle of the rectangular detector.

[0052] Signal processing circuit The calculation process includes: a single filter is often composed of a low-pass filter, a high-pass filter, and an all-pass lead filter in stages.

[0053] The transfer function of the low-pass filter is expressed as: ; In the formula, This is the 3dB frequency of the low-pass filter.

[0054] The transfer function of a high-pass filter is expressed as: ; In the formula, This is the 3dB frequency of the high-pass filter.

[0055] The transfer function of an all-pass lead filter is expressed as: ; In the formula, G 1 represents the all-pass gain. Based on the corresponding filter used (different types are multiplied), the signal processing circuit can be calculated. .

[0056] Finally, the system transfer function is obtained. The product of all transfer functions: ; Camera sensor noise calculation includes: camera sensor noise is divided into background noise, shot noise, and dark current noise in detector noise.

[0057] The magnitude of the background noise depends primarily on the detector's environment. This simulation mainly targets stellar backgrounds; therefore, the background noise primarily originates from stars, and the formula for calculating the number of photoelectrons generated by the detector is: ; In the formula, The star magnitude equivalent to the background. , The unit solid angle deep space background photon flux density is expressed in photons·m. -2 ·s -1 arcsec 2 ; This represents the effective entrance pupil area of ​​the optical system. It is the angular area of ​​a single pixel of the detector. It refers to the quantum efficiency of the detector relative to the background light. It is the exposure time of the background.

[0058] The formula for calculating the noise of a star sensor system is: ; Represents the conversion gain coefficient. The number of photoelectrons produced by the target radiation. This represents the number of photoelectrons produced by the dark current.

[0059] Star sensor voltage signal Image pixel position corresponding to the incident star Output voltage With detector noise The result is obtained by superposition.

[0060] ; ; S106. Perform ADC quantization processing on the star sensor voltage signal to obtain grayscale imaging results.

[0061] Optionally, the grayscale imaging result is represented as: ; in, This indicates the grayscale imaging result. This represents the star sensor voltage signal. This indicates the upper limit of the saturation voltage of the ADC. This indicates the number of quantization bits in the ADC.

[0062] To fully describe the star sensor full-link imaging modeling method under high-speed aerodynamic environment provided by the embodiments of the present invention Figure 2 An exemplary block diagram of an execution method for end-to-end imaging modeling of star sensors under high-speed aerodynamic conditions is shown, such as... Figure 2As shown, starting with stellar background modeling, the first step is to determine the star's position in the celestial sphere (coordinate transformation) and calculate its inherent radiant intensity (irradiance calculation). Next, starlight enters the atmospheric transmission modeling stage, where the attenuation of light by the Earth's atmosphere (atmospheric transmission), the radiation emitted by the atmosphere itself (path radiation), and wavefront distortion caused by atmospheric turbulence need to be considered. Subsequently, the simulation moves to aero-optical effects modeling, which simulates the impact of the flow field around the high-speed spacecraft on optical observations. Specifically, this includes calculating the changes in air refractive index caused by the flow field, the refractive index distribution in the optical window region, and tracking the transmission path and energy changes of the light rays accordingly. The processed light rays then enter the star sensor transmission modeling stage: first, the final landing point of the light rays on the camera image plane is calculated and photoelectric conversion is performed; then, the imaging quality of the optical system (space transfer function MTF) is evaluated; finally, camera sensor noise is superimposed. The final output of the entire process is a synthesized voltage signal corresponding to the location where the light rays fall onto the image plane, thus completing the end-to-end physical simulation of the electrical signal radiated from a distant star to the detector.

[0063] In summary, this invention provides a full-link imaging modeling method for star sensors under high-speed aerodynamic environments. First, by constructing a complete signal link from the star, atmospheric transmission, turbulence, aero-optics, the optical system, to the sensor, it addresses the problem of insufficient imaging simulation completeness in existing technologies. Then, by sequentially cascading star background modeling, atmospheric transmission modeling, atmospheric turbulence dynamic imaging fuzzy modeling, aero-optical transmission modeling, star sensor transmission modeling, and ADC quantization processing, it achieves effective fusion of the various local models, solving the problem of difficulty in integrating local research results with the full-link model. In particular, this invention specifically introduces aero-optical transmission modeling for high-speed aerodynamic environments, addressing the lack of full-link imaging simulation research under high-speed flow fields. Finally, through full-link modeling, it obtains more realistic star sensor voltage signals and grayscale imaging results, thereby enabling a more accurate assessment of the impact of aero-optical effects on star sensor performance, and providing an effective simulation tool for the development of high-precision star map simulation and navigation algorithms.

[0064] The method provided in this embodiment of the invention can be applied to electronic devices. Specifically, the electronic device can be a desktop computer, a portable computer, a smart mobile terminal, a server, etc., and this embodiment of the invention does not limit the application to such devices.

[0065] Based on the same inventive concept, this invention also provides a star sensor full-link imaging modeling device under high-speed aerodynamic environment. Figure 3 This is a schematic diagram of the structure of a star sensor full-link imaging modeling device under high-speed aerodynamic environment provided by an embodiment of the present invention, as shown below. Figure 3As shown, it includes: a star background modeling unit 301, an atmospheric transmission modeling unit 302, an atmospheric turbulence dynamic imaging modeling unit 303, an aero-optical transmission modeling unit 304, a star sensor transmission modeling unit 305, and an ADC quantization unit 306. The stellar background modeling unit 301 is used to acquire starlight emitted by all distant stars in the observation scene using a star sensor camera, and to perform stellar background modeling processing using starlight to obtain the first ray direction of the incident star and the first irradiance of the incident star. Atmospheric transport modeling unit 302 is used to perform atmospheric transport modeling processing based on the atmospheric radiation transport calculation model and using the first irradiance of the incident star to obtain the second irradiance of the incident star with atmospheric transport effect added. Atmospheric turbulence dynamic imaging modeling unit 303 is used to construct a blurred model of atmospheric turbulence dynamic imaging using Gaussian random functions and Kolmogorov turbulence theory. The aero-optical transmission modeling unit 304 is used to perform aero-optical transmission modeling processing on the first ray direction and the second irradiance of the incident star respectively, and obtains the second ray direction and the third irradiance of the incident star with aero-optical effects added. The star sensor transmission modeling unit 305 is used to perform star sensor transmission modeling based on the atmospheric turbulence dynamic imaging blur model, the direction of the second ray of the incident star and the third irradiance of the incident star, to obtain the star sensor voltage signal. The ADC quantization unit 306 is used to perform ADC quantization processing on the star sensor voltage signal to obtain grayscale imaging results.

[0066] Figure 4 This invention provides a schematic diagram of a star sensor full-link imaging modeling device under high-speed aerodynamic conditions, comprising: a processor 710, a storage medium 720, and a bus 730. The storage medium 720 stores machine-readable instructions executable by the processor 710. When the star sensor full-link imaging modeling device operates under high-speed aerodynamic conditions, the processor 710 communicates with the storage medium 720 via the bus 730. The processor 710 executes the machine-readable instructions to perform the steps of the above-described method embodiment. Specific implementation methods and technical effects are similar and will not be repeated here.

[0067] The storage medium may include random access memory (RAM) or non-volatile memory (NVM), such as at least one disk storage device. Optionally, the storage medium may also be at least one storage device located remotely from the aforementioned processor.

[0068] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0069] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0070] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings and the disclosure, will understand and implement other variations of the disclosed embodiments in carrying out the claimed invention. In this description, the word "comprising" does not exclude other components or steps, "a" or "an" does not exclude a plurality, and "a plurality" means two or more, unless otherwise explicitly specified. Furthermore, while different embodiments may describe certain measures, this does not mean that these measures cannot be combined to produce good results.

[0071] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the inventive concept, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for full-link imaging modeling of star sensors under high-speed aerodynamic conditions, characterized in that, include: The starlight emitted by all distant stars in the observation scene is acquired using a star sensor camera, and the starlight is used to perform stellar background modeling to obtain the first ray direction and the first irradiance of the incident star. Based on the atmospheric radiative transfer calculation model, and using the first irradiance of the incident star for atmospheric transfer modeling, the second irradiance of the incident star with atmospheric transfer effect is obtained. A dynamic imaging blur model of atmospheric turbulence was constructed using Gaussian random functions and Kolmogorov turbulence theory. Aerodynamic optical transmission modeling was performed on the first ray direction and the second irradiance of the incident star, respectively, to obtain the second ray direction and the third irradiance of the incident star with added aerodynamic optical effects. Based on the atmospheric turbulence dynamic imaging blur model, the direction of the second ray of the incident star, and the third irradiance of the incident star, star sensor transmission modeling is performed to obtain the star sensor voltage signal; The star sensor voltage signal is quantized by an ADC to obtain a grayscale imaging result.

2. The method for full-link imaging modeling of star sensors under high-speed aerodynamic conditions according to claim 1, characterized in that, The second irradiance of the incident star is expressed as: ； in, This represents the second irradiance of the incident star. This represents the first irradiance of the incident star. This represents the atmospheric transmittance calculated based on the MODTRAN atmospheric radiative transfer model. This represents the path radiation calculated based on the MODTRAN atmospheric radiative transfer model.

3. The method for full-link imaging modeling of star sensors under high-speed aerodynamic conditions according to claim 1, characterized in that, The atmospheric turbulence dynamic imaging fuzzy model is represented as follows: ； in, This represents a dynamic imaging blur model of atmospheric turbulence. Table of turbulence modulation transfer function, Represents the turbulent random modulation transfer function; ； ； ； ； ； in, Indicates spatial frequency, For space wavenumber, The refractive index is the structural constant. It is a Gaussian random function with a mean of 0 and a variance of 1, and has Hermitian symmetry; The power spectrum function representing atmospheric turbulence. Indicates the wavelength of starlight. This represents the correction factor for the finite aperture smoothing effect. This indicates the diameter of the receiving aperture of the star sensor camera in the star sensor system. This indicates the height of the star sensor camera.

4. The method for full-link imaging modeling of star sensors under high-speed aerodynamic conditions according to claim 1, characterized in that, The aero-optical transmission modeling process, which involves applying aero-optical effects to the first ray direction and the second irradiance of the incident star, yields the corresponding second ray direction and third irradiance of the incident star with added aero-optical effects, including: The refractive index field of the external flow field region was calculated based on the Gladstone-Dale expression. Based on the thermo-optical and elasto-optical effects corresponding to the optical window of the star sensor system, the refractive index field inside the optical window of the star sensor system is calculated. Based on the light transmission equation and Snell's law, the refractive index field of the outer flow field region and the refractive index field inside the optical window are used to transmit the direction of the first ray of the incident star sequentially in the outer flow field, the interface between the outer flow field and the optical window, and inside the optical window to obtain the direction of the second ray of the incident star. Based on Fresnel's law, the second irradiance of the incident star is transmitted at the interface of the optical window to obtain the third irradiance of the incident star.

5. The method for full-link imaging modeling of star sensors under high-speed aerodynamic conditions according to claim 1, characterized in that, The star sensor transmission modeling process, based on the atmospheric turbulence dynamic imaging blur model, the direction of the second ray from the incident star, and the third irradiance of the incident star, yields a star sensor voltage signal, including: The second ray direction of the incident star is processed by the star sensor camera image plane conversion to obtain the image plane pixel position corresponding to the incident star. The initial voltage signal of the star sensor in the star sensor system is calculated based on the third irradiance of the incident star. The spatial transfer function of the optical system, the spatial transfer function of the detector, and the spatial transfer function of the signal processing circuit are calculated separately. Then, the spatial transfer function of the optical system, the spatial transfer function of the detector, and the spatial transfer function of the signal processing circuit are multiplied by the atmospheric turbulence dynamic imaging blur model to obtain the final spatial transfer function. The noise of the star sensor system is obtained by combining the background noise, shot noise, and dark current noise in the detector noise. The star sensor voltage signal at the image pixel location is calculated using the initial voltage signal of the star sensor, the noise of the star sensor system, and the final spatial transfer function.

6. The method for full-link imaging modeling of star sensors under high-speed aerodynamic conditions according to claim 5, characterized in that, The initial voltage signal of the star sensor is represented as follows: ； ； in, This represents the value of the initial voltage signal of the star sensor. For detector gain, To be at starlight wavelength Lower detector responsivity, This represents the radiant flux from the star reaching the detector's pixels. The photosensitive area of ​​the detector pixel. For the transmittance of the optical system, This refers to the aperture number of the optical system. Indicates the third irradiance of the incident star. This indicates the lower limit of the integral of the detector's spectral response. This indicates the upper limit of the detector's spectral response integral.

7. The method for full-link imaging modeling of star sensors under high-speed aerodynamic conditions according to claim 5, characterized in that, The noise of the star sensor system is represented as follows: ； in, This represents the noise value of the star sensor system. This represents the conversion gain coefficient of the star sensor system. The number of photoelectrons produced by the target radiation. This indicates the number of photoelectrons generated by the detector in response to background noise. The number of photoelectrons produced by the dark current.

8. The method for full-link imaging modeling of star sensors under high-speed aerodynamic environment according to claim 1, characterized in that, The grayscale imaging result is expressed as follows: ； in, This indicates the grayscale imaging result. This represents the star sensor voltage signal. This indicates the upper limit of the saturation voltage of the ADC. This indicates the number of quantization bits in the ADC.

9. A star sensor full-link imaging modeling device under high-speed aerodynamic environment, characterized in that, The star sensor full-link imaging modeling device under high-speed aerodynamic environment includes: a star background modeling unit, an atmospheric transmission modeling unit, an atmospheric turbulence dynamic imaging modeling unit, an aero-optical transmission modeling unit, a star sensor transmission modeling unit, and an ADC quantization unit. The stellar background modeling unit is used to acquire starlight emitted by all distant stars in the observation scene using a star sensor camera, and to perform stellar background modeling processing using the starlight to obtain the first ray direction of the incident star and the first irradiance of the incident star. The atmospheric transport modeling unit is used to perform atmospheric transport modeling processing based on the atmospheric radiation transport calculation model and using the first irradiance of the incident star to obtain the second irradiance of the incident star with atmospheric transport effects added. The atmospheric turbulence dynamic imaging modeling unit is used to construct an atmospheric turbulence dynamic imaging fuzzy model using Gaussian random functions and Kolmogorov turbulence theory. The aero-optical transmission modeling unit is used to perform aero-optical transmission modeling processing on the first ray direction of the incident star and the second irradiance of the incident star respectively, and obtains the second ray direction of the incident star and the third irradiance of the incident star with aero-optical effects added. The star sensor transmission modeling unit is used to perform star sensor transmission modeling processing based on the atmospheric turbulence dynamic imaging blur model, the direction of the second ray of the incident star and the third irradiance of the incident star, to obtain the star sensor voltage signal. The ADC quantization unit is used to perform ADC quantization processing on the star sensor voltage signal to obtain a grayscale imaging result.

10. A full-link imaging modeling device for star sensors under high-speed aerodynamic conditions, characterized in that, include: The device includes a processor, a storage medium, and a bus. The storage medium stores machine-readable instructions executable by the processor. When the star sensor full-link imaging modeling device in a high-speed aerodynamic environment is running, the processor communicates with the storage medium via the bus. The processor executes the machine-readable instructions to perform the steps of the star sensor full-link imaging modeling method in a high-speed aerodynamic environment as described in any one of claims 1-8.

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