A full-automatic star calibration method for a ground-based photoelectric telescope

Abstract

The present application relates to the technical field of photoelectric detection, and provides a kind of ground-based photoelectric telescope full-automatic star calibration method, comprising: in the corresponding star map of current time, construct the star list for calibration;Iterate the star in the star list, based on the currently guided star, whether the deviation of the current azimuth and the real-time position of the current elevation of telescope is within the first threshold with the position of the star guided in current time;When within the first threshold, the centroid position of the currently guided star is acquired by image acquisition system, and the miss distance of the currently guided star is determined based on the centroid position;Telescope control system calculates miss distance variance based on the miss distance, and judges whether the miss distance variance is within the second threshold;When the miss distance variance is within the second threshold, the calibration data of the guided star is saved, and moves to the next star for automatic calibration, until all the stars in the star list are traversed.

Description

Technical Field

[0001] This application relates to the field of photoelectric detection technology, and more specifically, to a fully automated celestial calibration method for a ground-based photoelectric telescope. Background Technology

[0002] Ground-based photoelectric telescopes commonly employ manual stellar calibration to model and analyze static pointing errors, enabling real-time correction. Manual stellar calibration typically requires operators to visually determine whether the images transmitted from the image acquisition software to the telescope control software meet the calibration conditions; if not, manual adjustments are made. The entire process is cumbersome and requires human intervention. Given user demands for unmanned, simplified, and automated observation tasks, manual calibration proves inadequate.

[0003] To address the aforementioned issues, this application proposes a fully automated method for calibrating celestial bodies for ground-based photoelectric telescopes, enabling the calibration process to be completed automatically with a single click. Summary of the Invention

[0004] Some embodiments of this application provide a fully automated stellar calibration method for a ground-based photoelectric telescope, including:

[0005] In the star map corresponding to the current moment, construct a list of stars for calibration;

[0006] Traverse the stars in the star list, and based on the currently guided star, determine whether the deviation between the telescope's current azimuth and real-time elevation positions and the position of the guided star at the current moment is within a first threshold.

[0007] When the target is within the first threshold, the centroid position of the currently guided star is acquired by the image acquisition system, and the off-target amount of the currently guided star is determined based on the centroid position.

[0008] The telescope control system calculates the variance of the miss distance based on the miss distance and determines whether the variance of the miss distance is within a second threshold.

[0009] When the variance of the off-target is within the second threshold, the calibration data of the guided star is saved, and the calibration is moved to the next star for automatic calibration until all stars in the star list have been traversed.

[0010] In some embodiments, it also includes:

[0011] When the position is not within the first threshold, the telescope's current azimuth and pitch real-time position are automatically adjusted within a preset time range until the deviation of the star's position guided by the telescope at the current moment is within the first threshold.

[0012] In some embodiments, it also includes:

[0013] When the position is not within the second threshold, the telescope’s current azimuth and pitch real-time position are automatically adjusted within the preset time range until the deviation of the star position guided by the telescope at the current moment is within the first threshold and the variance of the miss is within the second threshold.

[0014] In some embodiments, the preset time refers to the sum of the maximum telescope turning time and the off-target measurement waiting time.

[0015] In some embodiments, the maximum telescope turning time refers to the time required for the telescope to turn from 0 degrees to 360 degrees; the off-target measurement waiting time is 15-30 seconds.

[0016] In some embodiments, determining the off-target distance of the currently guided star based on the centroid position includes:

[0017] Calculate the deviation distance of the centroid position from the center of the crosshair, in pixels;

[0018] The field of view corresponding to a single pixel, calculated by multiplying the deviation distance by an arcsecond, yields the off-target distance of the currently guided star.

[0019] In some embodiments, the variance of the miss distance satisfies the following condition: σ ≥ σ tele +a image p

[0020] Where σ is the variance of the miss distance, σ tele For telescope servo tracking accuracy; a image is the precision of stellar barycenter extraction, in pixels; p is the field of view corresponding to a single pixel of the camera, in arcseconds per pixel.

[0021] In some embodiments, constructing a list of stars for labeling in the star map corresponding to the current moment includes:

[0022] In the star chart corresponding to the current moment, 30 to 70 stars with an azimuth of 0 to 360 degrees, an elevation of 20 to 85 degrees, and a magnitude of 4 to 5 are randomly selected at even intervals to construct a star list for calibration.

[0023] In some embodiments, it also includes:

[0024] A calibration file is created to store the calibration data, which is used to solve the telescope static pointing error correction model.

[0025] In some embodiments, it also includes:

[0026] Based on the calibration data of all stars in the star list, the static pointing error of the telescope is corrected through the model solution module.

[0027] Compared with related technologies, the above-described solutions of this application have at least the following beneficial effects:

[0028] This application proposes a fully automated star calibration method for ground-based photoelectric telescopes, which improves upon the previous manual star calibration process by automating the calibration process. By checking whether the telescope is in place, whether the variance of the miss distance meets the threshold condition, and cyclically judging timeouts, the star calibration process is completed automatically.

[0029] This application can effectively solve the problem of human intervention required in the traditional manual star calibration process, and provides the necessary technical support for the unmanned, simplified and automated observation of ground-based photoelectric telescopes. It is applicable to all types of ground-based photoelectric telescopes, such as equatorial and horizontal telescopes. Attached Figure Description

[0030] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0031] Figure 1 A schematic flowchart of a fully automated stellar calibration method for a ground-based photoelectric telescope provided in some embodiments of this application;

[0032] Figure 2 The flowchart illustrates the fully automated stellar calibration method for ground-based photoelectric telescopes provided in some embodiments of this application. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the application. The singular forms “a,” “said,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0035] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0036] It should be understood that although the terms first, second, third, etc., may be used to describe embodiments of this application, these terms should not be used in isolation. These terms are only used to distinguish between different terms. For example, first may also be referred to as second without departing from the scope of embodiments of this application, and similarly, second may also be referred to as first.

[0037] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the article or device that includes said element.

[0038] When ground-based photoelectric telescopes track and measure targets in real time, they require real-time pointing corrections due to inherent systematic errors that change with the azimuth and elevation angles. A static pointing error correction model is typically established using calibration with multiple stars across the entire sky. Based on this model, the azimuth and elevation angles are corrected in real time during tracking to reduce pointing errors.

[0039] To establish a static pointing error correction model for ground-based photoelectric telescopes, the traditional method is to uniformly acquire stellar images across the entire sky, extract the miss distance, and then analyze the static pointing error correction model. Most methods calculate the static pointing error correction model based on various models and techniques. However, obtaining the correction model generally relies on manual intervention, often requiring manual star selection or manual determination of whether the stellar miss distance meets the requirements. This does not meet the requirements for unmanned, simplified, and automated telescope operation.

[0040] To address this, the present invention provides a fully automated star calibration method for a ground-based photoelectric telescope, comprising: constructing a star list for calibration in the star map corresponding to the current moment; traversing the stars in the star list, and determining, based on the currently guided star, whether the deviation between the telescope's current azimuth and elevation real-time positions and the position of the currently guided star is within a first threshold; when within the first threshold, acquiring the centroid position of the currently guided star through an image acquisition system, and determining the miss distance of the currently guided star based on the centroid position; the telescope control system calculating the miss distance variance based on the miss distance, and determining whether the miss distance variance is within a second threshold; when the miss distance variance is within the second threshold, saving the calibration data of the guided star, and moving to the next star for automatic calibration, until all stars in the star list have been traversed.

[0041] This application proposes a fully automated star calibration method for ground-based photoelectric telescopes, which improves upon the previous manual star calibration process by automating the calibration process. By checking whether the telescope is in place, whether the variance of the miss distance meets the threshold condition, and cyclically judging timeouts, the star calibration process is completed automatically.

[0042] The present application will now be described in detail with reference to the accompanying drawings.

[0043] like Figure 1 As shown, some embodiments of this application provide a fully automated stellar calibration method for a ground-based photoelectric telescope. The fully automated stellar calibration process is completed collaboratively by two software systems: a telescope control software system and an image processing software system. The telescope control software system is responsible for controlling the telescope and executing the fully automated stellar calibration; the image processing software system is responsible for extracting the off-target amount of the stellar image. Specifically, the method includes the following steps:

[0044] Step S102: Construct a list of stars for calibration in the star map corresponding to the current moment;

[0045] Step S104: Traverse the stars in the star list, and based on the currently guided star, determine whether the deviation between the telescope's current azimuth and real-time elevation positions and the position of the guided star at the current moment is within a first threshold.

[0046] Step S106: When within the first threshold, the centroid position of the currently guided star is acquired through the image acquisition system, and the off-target amount of the currently guided star is determined based on the centroid position.

[0047] Step S108: The telescope control system calculates the variance of the miss distance based on the miss distance and determines whether the variance of the miss distance is within the second threshold.

[0048] Step S110: When the variance of the off-target is within the second threshold, save the calibration data of the guided star and move to the next star for automatic calibration until all stars in the star list have been traversed.

[0049] Before step S102, the automatic calibration button needs to be clicked in the telescope control software system to start the fully automatic stellar calibration program. Optionally, a calibration file can be created in the telescope control software system. The calibration data used in the subsequent calibration process will be stored in this file and used for solving the telescope's static pointing error correction model.

[0050] In step S102, constructing a star list for calibration in the star map corresponding to the current time includes: randomly selecting 30 to 70 stars with an azimuth of 0–360 degrees, an elevation of 20–85 degrees, and a magnitude of 4–5 from the star map corresponding to the current time at uniform intervals to construct a star list for calibration. The specific number of calibration stars can be dynamically adjusted and is not strictly limited.

[0051] After the star list is constructed, a star is selected as the current guiding star, and this process is repeated for all stars in the list. The telescope control software system automatically guides the telescope to point to the next star in sequence. The pointing position of the star is calculated in real time, and it is determined whether the deviation between the telescope's current azimuth and elevation positions and the position of the currently guided star is within a first threshold. The first threshold is usually preset in the telescope control software system according to accuracy requirements. The first threshold includes a preset range of azimuth and elevation angles, and the specific values ​​are not limited. For example, the azimuth angle is within ±2 arcseconds, and the elevation angle is within ±2 arcseconds. When the deviation between the telescope's current azimuth and elevation positions and the position of the currently guided star is within the first threshold, the image acquisition system acquires the centroid position of the currently guided star, and the miss distance of the currently guided star is determined based on the centroid position.

[0052] When a telescope is pointed at a star, the deviation of the azimuth and elevation angles relative to the center of the crosshairs at the current moment is called the miss distance. The miss distance satisfies the following relationship:

[0053] A = A e +ΔA

[0054] E = E e +ΔE

[0055] Where A and E are the azimuth and elevation angles of the star, respectively. e and E e These are the azimuth and pitch angles output by the encoder, respectively, and ΔA and ΔE are the miss distance values ​​for azimuth and pitch, respectively.

[0056] In some embodiments, determining the miss distance of the currently guided star based on the centroid position includes: calculating the deviation distance of the centroid position from the center of the crosshairs, in pixels; multiplying the deviation distance by the field of view corresponding to a single pixel in arcseconds to obtain the miss distance of the currently guided star.

[0057] In some embodiments, when the deviation between the telescope's current azimuth and pitch positions and the star position it is guiding at the current moment is not within a first threshold, the telescope's current azimuth and pitch positions are automatically adjusted within a preset time range until the deviation between the telescope's current star position and the star position it is guiding at the current moment is within the first threshold.

[0058] Furthermore, when the deviation between the telescope's current azimuth and pitch real-time position and the star position guided at the current moment is within a first threshold, the telescope control system calculates the variance of the miss based on the miss amount and determines whether the variance of the miss amount is within a second threshold.

[0059] In some embodiments, the variance of the off-target amount satisfies the following second threshold condition:

[0060] σ≥σ tele +a image p;

[0061] Where σ is the variance of the miss distance, σ tele For telescope servo tracking accuracy; a image is the precision of stellar barycenter extraction, in pixels; p is the field of view corresponding to a single pixel of the camera, in arcseconds per pixel.

[0062] In some embodiments, when the variance of the miss distance is not within the second threshold, the telescope’s current azimuth and pitch real-time position are automatically adjusted within the preset time range until the deviation of the star position guided by the telescope at the current moment is within the first threshold and the variance of the miss distance is within the second threshold.

[0063] The preset time refers to the sum of the maximum telescope turning time and the off-target measurement waiting time. In some embodiments, the maximum telescope turning time refers to the time required for the telescope to turn from 0 degrees to 360 degrees; the off-target measurement waiting time is 15-30 seconds, for example, 20 seconds. The calibration of a single star needs to determine whether it has timed out; otherwise, the calibration time may not end or may last too long.

[0064] When the variance of the miss distance is within the second threshold, the calibration data of the guided star is saved, and the system moves to the next star for automatic calibration until all stars in the star list have been traversed. The telescope software system automatically saves the miss distance data (including timestamps) into the calibration file for later use.

[0065] In some embodiments, the method further includes: correcting the telescope's static pointing error using a model calculation module based on the calibration data of all stars in the star list. Specifically, the calibration data can be calculated using either the single-difference method or the spherical harmonic difference method to obtain the telescope's static pointing error correction model. The specific algorithm is not detailed here, but can be found in relevant technical implementations.

[0066] Following the above procedure, a ground-based altazimuth photoelectric telescope was tested. Experiments show that this method can automatically perform stellar calibration for ground-based photoelectric telescopes. Furthermore, this method has been applied and verified in actual engineering projects with good results.

[0067] This application proposes a fully automated star calibration method for ground-based photoelectric telescopes, which improves upon the previous manual star calibration process by automating the calibration process. By checking whether the telescope is in place, whether the variance of the miss distance meets the threshold condition, and cyclically judging timeouts, the star calibration process is completed automatically.

[0068] This application can effectively solve the problem of human intervention required in the traditional manual star calibration process, and provides the necessary technical support for the unmanned, simplified and automated observation of ground-based photoelectric telescopes. It is applicable to all types of ground-based photoelectric telescopes, such as equatorial and horizontal telescopes.

[0069] Finally, it should be noted that the various embodiments in this specification are described by way of example, and each embodiment focuses on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0070] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for full-automatic star calibration of a ground-based optical telescope, characterized in that ,comprising: constructing a star list for calibration in a star map corresponding to the current time; traversing the stars in the star list, judging whether the deviation of the current azimuth and elevation real-time position of the telescope from the position of the currently guided star is within a first threshold based on the currently guided star; when within the first threshold, acquiring the centroid position of the currently guided star through an image acquisition system, and determining the off-target amount of the currently guided star based on the centroid position; the telescope control system calculates the off-target amount variance based on the off-target amount, and judges whether the off-target amount variance is within a second threshold; when the off-target amount variance is within the second threshold, saving the calibration data of the guided star, and moving to the next star for automatic calibration until all stars in the star list are traversed; The off-target amount variance satisfies the following condition: σ ≥ σ tele + a image p where σ is the off-target amount variance, σ tele is the telescope servo tracking accuracy; a image is the star centroid extraction accuracy, in pixels; p is the field of view corresponding to a single pixel of the camera, in arcsec per pixel.

2. The method of claim 1, wherein , further comprising: when not within the first threshold, automatically adjusting the current azimuth and elevation real-time position of the telescope within a preset time range until the deviation of the currently guided star position from the current time is within the first threshold.

3. The method of claim 2, wherein , further comprising: when not within the second threshold, automatically adjusting the current azimuth and elevation real-time position of the telescope within the preset time range until the deviation of the currently guided star position from the current time is within the first threshold and the off-target amount variance is within the second threshold.

4. The method of claim 3, wherein , the preset time refers to the sum of the maximum turning time of the telescope and the off-target amount acquisition waiting time.

5. The method of claim 4, wherein , the maximum turning time of the telescope refers to the time required for the telescope to turn from 0 degrees to 360 degrees; the off-target amount acquisition waiting time is 15-30 seconds.

6. The method of claim 1, wherein , the determination of the off-target amount of the currently guided star based on the centroid position comprises: calculating the deviation distance of the centroid position from the center of the crosshair in pixels; the deviation distance multiplied by the field of view corresponding to a single pixel in angular seconds to obtain the off-target amount of the currently guided star.

7. The method of claim 1, wherein , the construction of the star list for calibration in the star map corresponding to the current time comprises: in the star map corresponding to the current time, 30-70 stars with azimuth 0-360 degrees, elevation 20-85 degrees, and magnitude 4-5 are randomly selected at equal intervals to construct a star list for calibration.

8. The method of claim 1, wherein , further comprising: establishing a calibration file for storing the calibration data, which is used for solving the static pointing error correction model of the telescope.

9. The method of claim 1, wherein , further comprising: based on the calibration data of all stars in the star list, the static pointing error correction of the telescope is performed through a model solving module.

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