A zero position correction method and correction system for a follow-up dome

Abstract

The present invention relates to the field of mobile dome control technology, and specifically provides a mobile dome zero position correction method and correction system, wherein the main control system obtains the direction of the North Star, guides the mobile dome and the telescope according to the direction of the North Star, collects the telescope field image through the telescope and identifies whether the telescope field image contains the North Star, and the main control system determines whether there is an error in the mobile dome zero position according to the identification result and the opening angle of the mobile dome skylight, and if there is, it is corrected, and the above process is repeated until the mobile dome zero position error is within an acceptable range, and it is considered that the mobile dome zero position has no error. The mobile dome zero position correction method and correction system provided by the present invention have a simple structure, do not rely on too many additional equipment, are low in cost, are easy to implement, and the iterative process is short, does not take up too much time, can be completed in the idle time of the telescope task, and is more convenient.

Description

Technical Field

[0001] The invention relates to the technical field of follow-up dome control, and in particular provides a zero position correction method and correction system for a follow-up dome. Background Art

[0002] In recent years, telescopes based on infrared bands that can be used for daytime observations have gradually become the focus of research at domestic and foreign scientific research institutions. For daytime observation telescopes, when the angle between the telescope and the sun is greater than a certain angle, the detection capability of traditional telescopes at night can reach more than 90%. For such telescopes with daytime observation capabilities, a follow-up dome is needed to protect them. Unlike traditional telescope protection domes, the skylight of the follow-up dome can only be opened to a smaller angle. The follow-up dome rotates synchronously with the change of the telescope's azimuth angle, so that the telescope can always observe space targets during the rotation process.

[0003] The telescope is inside the moving dome, and the hemisphere of the moving dome can rotate freely within the range of 0~360°. The horizontal opening angle of the moving dome skylight is about 30°. When using the telescope to observe a target, the azimuth and elevation angle of the target are usually sent to the telescope servo system, and the azimuth is sent to the moving dome at the same time, so that the moving dome can follow the rotation of the telescope. In order to use the same azimuth angle guidance value to guide the telescope and the moving dome at the same time, it is usually necessary to perform zero-position correction on the telescope and the moving dome. Through zero-position correction, the telescope can be observed without being blocked by the moving dome throughout the process, achieving the best observation effect.

[0004] The telescope is a precision optical device. After the zero position correction is performed, there is generally no need to re-correct the zero position unless there is foundation settlement, crustal movement, etc. The follower dome is not a precision mechanical equipment. It will produce a certain vibration during the movement. This vibration will cause a small probability of transmission loss in the transmission system between the follower dome and the encoder during the rotation of the follower dome. This loss causes the zero position of the telescope to be misaligned with the actual zero position of the follower dome. After a certain period of time (such as one month), the telescope may be completely blocked by the follower dome. At this time, neither the main control system nor the follower dome control system is aware of the misalignment. From the data feedback, the telescope and the follower dome are still pointing in the same direction, but the telescope cannot observe the target. When the telescope cannot observe the target, it is generally difficult for the operator to consider the zero position misalignment of the follower dome. Usually, factors such as target track change, defocus or inaccurate camera parameters are considered, resulting in a lot of observation time being wasted. Based on the above problems, it is necessary to periodically correct the zero position of the follower dome. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a zero position correction method and correction system for a servo dome. The main control system guides the telescope and the servo dome according to the direction of the North Star, obtains the telescope field image through the telescope, and adjusts the zero position of the servo dome according to whether the telescope field image contains the North Star and the opening angle of the servo dome skylight. The method does not require additional structural support, is easy to implement and has high reliability, and can be performed during the idle time of the servo dome without affecting the servo dome mission.

[0006] The zero position correction method of the follower dome provided by the present invention comprises:

[0007] S1: Obtain the direction of the North Star, use the direction of the North Star as the telescope guidance data to guide the telescope, and use the azimuth of the direction of the North Star as the guidance data of the follow-up dome to guide the follow-up dome;

[0008] S2: Obtain the telescope field image through the telescope and identify whether the telescope field image contains the North Star:

[0009] If the image of the telescope field of view does not contain the North Star, the zero position of the moving dome is corrected until the North Star appears in the image of the telescope field of view, and S3 is executed;

[0010] S3: If the telescope field of view contains the North Star, determine the opening angle of the moving dome skylight Is it less than 5°?

[0011] like , it is considered that there is no error in the zero position of the follow-up dome, and the correction of the zero position of the follow-up dome is completed;

[0012] like , then the opening angle of the follow-up dome skylight is reduced by 1°, and S2 and S3 are repeated.

[0013] Preferably, the method for identifying whether the telescope field image contains the North Star is:

[0014] Q1: Binarize the telescope field of view image to obtain a binary telescope field of view image;

[0015] Q2: Obtain the maximum connected region in the binary telescope field of view image through the connected region algorithm;

[0016] Q3: Compare the maximum connected area with the preset North Star threshold:

[0017] If the maximum connected area is not less than the North Star threshold, it is determined that the telescope field of view image contains the North Star;

[0018] If the maximum connected area is smaller than the North Star threshold, it is determined that the telescope field of view image does not contain the North Star.

[0019] Preferably, the connected region algorithm is an eight-connected region algorithm.

[0020] Preferably, the North Star threshold value is 20.

[0021] A zero position correction system of a servo dome based on a zero position correction method of a servo dome, comprising a main control system, an image system, a telescope and a servo dome;

[0022] The main control system is used to control the telescope and the follow-up dome;

[0023] The imaging system is used to receive the telescope field image and identify whether the telescope field image contains the North Star.

[0024] Preferably, the main control system includes a guiding module, and the guiding module can adjust the azimuth opening angle of the follow-up dome skylight.

[0025] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0026] The following dome zero position correction method and zero position correction system provided by the embodiment of the present invention guide the following dome and the telescope according to the direction of the North Star, and judge whether there is an error in the following dome zero position according to whether the telescope can observe the North Star when the following dome skylight is opened at an angle less than 5°. The method does not rely on additional hardware equipment, is low in cost and easy to implement, and the correction cycle process only generates a small number of iterations, takes a short time, and has a high correction efficiency. The following dome zero position correction can be performed during the idle time of the telescope observation task, will not affect the normal progress of the task, and can be periodically corrected according to demand, thereby solving the problem of the telescope being blocked by the following dome due to long-term accumulated misalignment, reducing the troubleshooting time of such faults, and increasing the effective observation time.

[0027] Moreover, in the control system provided by the embodiment of the present invention, the communication connection method between the various hardware devices is not limited to serial port cables, network cables, USB and camlink. The main control system and the image system can be deployed on the same computer or on different computers, and the main control system and the image system can be the same software or different software. It is flexible in application, convenient in operation and highly adaptable. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a flow chart of a method for correcting the zero position of a follow-up dome according to an embodiment of the present invention;

[0029] Figure 2 1 is a structural diagram of a follow-up dome zero position correction system provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0032] like Figure 1 As shown, an embodiment of the present invention provides a method for zero position correction of a follower dome, which is specifically as follows:

[0033] S1: The embodiment of the present invention uses the North Star as a basis to perform zero-position correction of the servo dome. The telescope is arranged inside the servo dome, and a servo dome skylight is provided on the dome hemisphere. The telescope can observe the target through the servo dome skylight, and the dome hemisphere can rotate freely within the range of 0° to 360°. Because the skylight is an arc-shaped gap opened along the dome hemisphere, when controlling the servo dome, only its azimuth angle needs to be considered, and no pitch motion control is required. The arc-shaped servo dome skylight can meet the observation requirements of the telescope in the pitch direction. The servo dome skylight can expand a predetermined angle along the azimuth direction, and the angle size can be adjusted. The telescope observes the target through the servo dome skylight. When the servo dome zero-position error is within an acceptable range, it will not cause abnormal obstruction of the telescope.

[0034] It should be noted that the zero position of the moving dome cannot achieve the ideal state of zero error. Therefore, it is only necessary to control the zero position error of the moving dome within an acceptable range. The zero position of the moving dome can be considered to be error-free. When the zero position error of the moving dome is within an acceptable range, the moving dome skylight will not cause abnormal obstruction to the telescope and can meet the normal observation needs of the telescope.

[0035] Based on the North Star, obtain the direction of the North Star, use the direction of the North Star as the telescope guidance data to guide the telescope to rotate, so that the telescope always points to the North Star and tracks the North Star. Open the follow-up dome skylight, use the azimuth in the direction of the North Star as the follow-up dome guidance data to guide the follow-up dome to rotate, so that the follow-up dome skylight always points to the North Star.

[0036] S2: In this state, the telescope always points to the North Star. If the zero position error of the moving dome is within an acceptable range, the telescope can observe the North Star and obtain a series of telescope field of view images through the telescope.

[0037] After obtaining the telescope field of view image, the telescope field of view image is processed. It is identified whether the telescope field of view image contains the North Star, and then it is determined whether the telescope has successfully captured the image of the North Star. The method for identifying whether the telescope field of view image contains the North Star is:

[0038] Q1: Binarize the telescope field of view image taken by the telescope to obtain a binarized telescope field of view image. Image binarization is also called image threshold segmentation. Its main function is to distinguish the foreground and background of the image. Image binarization is a mature prior art. The image binarization method used in the embodiment of the present invention is as follows:

[0039] According to the actual content of the telescope field of view image obtained by the telescope, a grayscale threshold is selected , determine the telescope field of view image Every pixel Gray value With gray threshold If the pixel Gray value Less than gray threshold , then the gray value of the point is set to 0; if the pixel Gray value Greater than or equal to gray threshold , then the gray value of the point is set to 255. The details are as follows:

[0040] ;

[0041] in, Indicates that the coordinates in the binarized telescope field of view image are The grayscale value of the pixel.

[0042] After the above processing, the telescope field of view image is converted into a binary telescope field of view image.

[0043] Q2: After binarizing the telescope field of view image, the maximum connected region in the binarized telescope field of view image is obtained by a connected region algorithm. There are many connected region algorithms, and the commonly used ones are a four-connected region algorithm and an eight-connected region algorithm. The embodiment of the present invention adopts an eight-connected region algorithm. The method for obtaining the maximum connected region is as follows:

[0044] Select any coordinate in the binarized telescope field of view image as The gray value of the pixel is 255, and the pixels located at the pixel Are the grayscale values ​​of the eight adjacent pixels above, below, left, right, upper left, upper right, lower left, and lower right 255? If so, the pixel is connected to the pixel. A connected area is formed. If not, it is not connected. Based on the newly identified connected pixels, the grayscale values ​​of the eight pixels above, below, left, right, upper left, upper right, lower left and lower right of the connected pixel are detected in turn to see if they are 255. If so, they are also connected pixels and are merged into the pixel The above detection process is repeated until the grayscale values ​​of the eight pixels above, below, left, right, upper left, upper right, lower left and lower right of all detected pixels are not equal to 255. The connected areas with grayscale values ​​of 255 are formed as connected areas.

[0045] All connected areas in the binary telescope field of view image are obtained. In addition to the North Star, the above connected areas may also contain noise. It is necessary to identify and distinguish the noise to further obtain the accurate connected areas belonging to the North Star.

[0046] Q3: Since the present invention only needs to identify whether the telescope field of view image contains the North Star, it only needs to determine whether the largest connected area is the North Star. Set the North Star threshold and compare the largest connected area among all connected areas with the preset North Star threshold:

[0047] If the maximum connected area is not less than the North Star threshold, the maximum connected area is determined to be the North Star, and the telescope field of view image contains the North Star.

[0048] If the maximum connected area is smaller than the North Star threshold, it is determined that the telescope field of view image does not contain the North Star.

[0049] If the telescope field of view image does not contain the North Star, the telescope has not successfully captured the North Star. It is considered that there is an unacceptable error in the zero position of the moving dome, causing the moving dome to abnormally block the telescope. The moving dome zero position is corrected, and the telescope field of view image is obtained through the telescope again. The above recognition process is repeated until the North Star appears in the telescope field of view image.

[0050] Correcting the zero position of the servo dome means turning the direction of the servo dome skylight to the direction of the telescope so that it is consistent with the direction of the telescope. The method of correcting the zero position of the servo dome is as follows:

[0051] use Indicates the number of times the opening angle of the dome skylight decreases. , correspondingly, the zero position of the corrected moving dome is The second amendment, When you correct the zero position of the servo dome for the first time, you may need to adjust the zero position of the servo dome repeatedly. Set the adjustment direction of the first adjustment of the zero position of the servo dome as the positive direction. During the correction process, the zero position adjustment method and adjustment amount of the follow-up dome are as follows: The adjustment degrees and directions of the zero position of the moving dome are +2°, -4°, +6°, -8°, etc., where "+" and "-" represent the adjustment directions of the zero position of the moving dome. After each adjustment, the telescope is used to collect images of the telescope field of view and identify whether the image contains the North Star. If not, the next adjustment of this correction is continued until the North Star appears in the telescope field of view. After the opening angle of the first follow-up dome skylight decreases, the corresponding The follow-up dome zero position correction is completed.

[0052] S3: If the image of the telescope field of view contains the North Star, it is necessary to identify the opening angle value of the follow-up dome skylight. If the opening angle of the follow-up dome skylight is too large when the telescope photographs the North Star, it cannot be said that the zero position error of the follow-up dome skylight is within an acceptable range. At this time, the successful photographing of the North Star is only because the opening angle of the follow-up dome skylight is too large, which can compensate for the abnormal occlusion caused by the zero position error. The embodiment of the present invention uses 5° as the dividing line to judge the opening angle of the follow-up dome skylight Is it less than 5°?

[0053] like , it is considered that the line connecting the center of the telescope field of view and the North Star passes through the center line of the moving dome skylight, that is, the moving dome zero position error is within the acceptable range, it is considered that the moving dome zero position has no error, there is no abnormal obstruction of the telescope, and the moving dome zero position correction is completed;

[0054] like , then the opening angle of the follow-up dome skylight is reduced by 1°, the telescope field of view image is acquired through the telescope again, and the above S2 and S3 are executed until the telescope successfully captures the North Star when the opening angle of the follow-up dome skylight is less than 5°.

[0055] In order to implement the above-mentioned follow-up dome zero position correction method, the embodiment of the present invention also provides a follow-up dome zero position correction system, such as Figure 2 As shown, the correction system includes a main control system, an image system, a telescope and a follow-up dome. The main control system includes a guidance module and a main control interaction module, the image system includes an image processing module and an image interaction module, the telescope includes a telescope control module and an image acquisition module, and the follow-up dome includes a follow-up dome control module.

[0056] The guidance module of the main control system is connected to the servo dome control module and the telescope control module respectively, the main control interaction module is connected to the image interaction module, and the image processing module is connected to the image acquisition module. The main control system obtains the direction of the North Star, and the guidance module sends the direction of the North Star and the azimuth of the North Star to the servo dome control module and the telescope control module respectively. The servo dome control module receives the azimuth of the North Star and uses the azimuth of the North Star as the servo dome guidance data to guide the servo dome to rotate; the telescope control module receives the direction of the North Star and uses the direction of the North Star as the telescope guidance data to guide the telescope to rotate. In this guidance state, if the zero position error of the servo dome is within an acceptable range, the servo dome will not cause abnormal obstruction to the telescope, and the telescope can track the North Star normally and obtain the image of the North Star.

[0057] At the same time, the guidance module of the main control system can adjust the opening angle of the follow-up dome skylight, and can fine-tune the opening angle of the follow-up dome skylight to increase or decrease.

[0058] The image acquisition module of the telescope collects the image of the telescope field of view, and sends the image of the telescope field of view to the image processing module of the image system. After receiving the image of the telescope field of view, the image processing module processes the image of the telescope field of view, identifies whether the image of the telescope field of view contains the North Star, and sends the identification result to the image interaction module, and then sends the identification result to the main control system through the image interaction module.

[0059] The main control system determines whether there is an unacceptable error in the zero position of the servo dome based on the recognition result and whether the opening angle of the servo dome skylight is less than 5°. If the opening angle of the servo dome skylight is less than 5° and there is the North Star in the telescope field of view image, it is considered that the line connecting the center of the telescope field of view and the North Star passes through the center line of the servo dome skylight, and the zero position error of the servo dome is within the acceptable range. It is considered that there is no error in the zero position of the servo dome, and the zero position correction is completed; if there is no North Star in the telescope field of view image, the servo dome correction value is adjusted and the telescope is re-calibrated. The North Star is identified by re-collecting the image of the telescope field of view. If the North Star exists in the image of the telescope field of view and the opening angle of the moving dome skylight is not less than 5°, the opening angle of the moving dome skylight is reduced by 1°, and the image of the telescope field of view is collected again to identify the North Star. If the opening angle of the moving dome skylight is less than 5° and the North Star exists in the image of the telescope field of view, it is considered that the line connecting the center of the telescope field of view and the North Star passes through the center line of the moving dome skylight, the zero position error of the moving dome is within an acceptable range, and the zero position correction of the moving dome is completed.

[0060] In particular, in the control system provided by the embodiment of the present invention, the communication connection method between the various hardware devices is not limited to serial port cables, network cables, USB and camlink. The main control system and the image system can be deployed on the same computer or on different computers, and the main control system and the image system can be the same software or different software, which is flexible in application and strong in adaptability.

[0061] In particular, since a large-field optical system usually sees more than one star when observing stars, making it difficult to identify the North Star, the present invention is suitable for a small-field optical system. The field of view of the telescope used in the experiment is a diagonal of 10′. When the telescope observes the North Star, only one North Star appears in the image, and there will be no other interference.

[0062] The embodiments of the present invention have been tested at an observation station in Yunnan Province, and the results were in line with expectations, proving that the system and method are effective.

[0063] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0064] The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for zero position correction of a moving dome. It is characterized in that include: S1: Acquire the direction of the North Star, use the direction of the North Star as telescope guidance data to guide the telescope, and use the azimuth of the direction of the North Star as follow-up dome guidance data to guide the follow-up dome; S2: Obtain a telescope field image through a telescope, and identify whether the telescope field image contains the North Star: If the image of the telescope field of view does not contain the North Star, the zero position of the moving dome is corrected until the North Star appears in the image of the telescope field of view, and S3 is executed; S3: If the telescope field of view contains the North Star, determine the opening angle of the moving dome skylight Is it less than 5°? like , it is considered that there is no error in the zero position of the follow-up dome, and the correction of the zero position of the follow-up dome is completed; like , then the opening angle of the follow-up dome skylight is reduced by 1°, and S2 and S3 are repeated.

2. The zero position correction method of the follow-up dome according to claim 1, It is characterized in that The method for identifying whether the telescope field image contains the North Star is: Q1: binarizing the telescope field of view image to obtain a binary telescope field of view image; Q2: Obtaining the maximum connected region in the binary telescope field of view image by a connected region algorithm; Q3: Compare the maximum connected area with the preset North Star threshold: If the maximum connected area is not less than the North Star threshold, it is determined that the telescope field of view image contains the North Star; If the maximum connected area is smaller than the North Star threshold, it is determined that the telescope field of view image does not contain the North Star.

3. The zero position correction method of the follow-up dome according to claim 2, It is characterized in that The connected region algorithm is an eight-connected region algorithm.

4. The zero position correction method of the follow-up dome according to claim 2, It is characterized in that The North Star threshold value is 20.

5. A zero position correction system for a follower dome based on the zero position correction method for a follower dome according to any one of claims 1 to 4, It is characterized in that It includes the main control system, imaging system, telescope and tracking dome; The main control system is used to control the telescope and the follow-up dome; The image system is used to receive the telescope field of view image and identify whether the telescope field of view image contains the North Star.

6. The zero position correction system of the moving dome according to claim 5, It is characterized in that The main control system includes a guiding module, and the guiding module can adjust the azimuth opening angle of the follow-up dome skylight.

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