Star sensor installation correction method and system based on solar image

Abstract

The application provides a sun image-based star sensor installation correction method and system, which comprises the following steps: making a satellite continuously collect sun full-disk images in a steady-state sun-seeking mode; adopting a fitting method to perform edge detection and sun center extraction, and performing multi-frame averaging on the centroid coordinates; determining a satellite correction angle according to the sun full-disk images and the relationship between a sun space telescope phase plane coordinate system and a satellite body coordinate system, so as to ensure that the sun images are in the center of a field of view; and calculating a star sensor installation matrix correction value according to the satellite correction angle, so as to realize sun image-based star sensor installation correction. The application can meet the needs of future sun exploration missions, provides a good technical means for high-precision sun observation of a space science satellite, and has engineering application value.

Description

Technical Field

[0001] This invention relates to the field of spacecraft, and more specifically, to a method and system for installing and correcting star sensors based on solar images. Background Technology

[0002] The Sun is the source of life. Comprising 99.86% of the solar system's mass, the Sun is the dominant factor in the Earth-Sun space environment, and solar activity is closely related to human sustainable development. Throughout the history of human civilization, studying and understanding the Sun has always been a top priority for scientists both domestically and internationally. Compared to ground-based solar telescopes, solar space exploration offers advantages such as being unaffected by Earth's atmospheric turbulence and absorption effects, and allowing for long-term continuous observation, thus bringing about revolutionary breakthroughs in solar physics research.

[0003] Patent document CN103323031A discloses a method for online compensation of system errors of a horizon instrument based on a star sensor. The method updates and calculates the horizon instrument attitude by correcting the interpolation table. However, this method is a compensation method for the horizon instrument when both the star sensor and the horizon instrument are available.

[0004] Patent document CN103344872A discloses a method for testing the polarity of a star sensor mount. It verifies the polarity of the star sensor mount by examining the relationship between the satellite's three-axis attitude change pattern and the rotation mode of the static optical star model. However, this method is a polarity test method.

[0005] Patent document CN107747946A discloses an online identification and compensation method for orbital periodic system errors between star sensors. It uses a linear interpolation algorithm to invert and obtain the system error between the star sensor to be compensated and the reference star sensor at any position on the orbit and then performs compensation. However, this method is a method for compensating orbital periodic system errors of star sensors.

[0006] Patent document CN1939807A discloses a method for on-orbit calibration based on the WENG imaging model of a star sensor and through parameter calculation, but this method is an on-orbit calibration method based on star sensor imaging.

[0007] Patent document CN1948085A discloses a method that combines attitude estimation process and star sensor parameter calibration simultaneously. This method eliminates the influence of attitude error on star sensor parameters, but it is an on-orbit calibration method based on star sensor distortion model.

[0008] Currently, no research has been conducted on star sensor installation and correction methods based on solar images. The solar field of view is only 32′. After the satellite experiences vibrations during the active phase, both the star sensor and the solar space telescope undergo deformation, making it impossible to guarantee a complete solar image within the telescope's field of view, thus failing to meet the requirements of very high-precision space science exploration. Therefore, research on star sensor calibration methods is needed. Summary of the Invention

[0009] In view of the deficiencies in the prior art, the purpose of this invention is to provide a method and system for correcting the installation of a star sensor based on solar images.

[0010] A method for installing and correcting a star sensor based on a solar image, provided by the present invention, includes:

[0011] Step 1: In steady-state solar observation mode, the satellite controls the solar space telescope to continuously acquire images of the solar surface;

[0012] Step 2: For the solar disk image, perform edge detection and heliocentric extraction, and perform multi-frame averaging of the centroid coordinates of the solar image;

[0013] Step 3: Based on the solar image and the relationship between the phase plane coordinate system of the solar space telescope and the satellite's body coordinate system, determine the angle that the satellite needs to correct so that the solar image is centered in the field of view;

[0014] Step 4: Calculate the correction value of the star sensor installation matrix based on the satellite correction angle.

[0015] Preferably, in step 2, edge detection is performed using a fitting method. This fitting method first uses an edge detection algorithm to extract edge points from the solar image, and then uses the least squares method to fit the edge points to a circle, with the center of the circle being the centroid of the solar image. The edge point coordinates are assumed to be (x1 y1), ..., (x...). N y N N is the number of edge points, (ab) is the coordinate of the center of the circle, R is the radius, and R is the true value of the centroid.

[0016] The circle is represented as A(x) 2 +y 2 )+Bx+Cy+D=0, A≠0; (xy) are the coordinates of the edge point;

[0017] The parameters are related as follows:

[0018]

[0019] The objective function F is optimized using the least squares circle fitting method.

[0020]

[0021] To calculate the minimum of the objective function F(A,B,C,D), we differentiate with respect to the circular parameters to obtain estimated values ​​of the parameters. The estimated coordinates of the center of the circle are obtained from the parametric relationship. and radius parameters.

[0022] Preferably, in step 3, according to the solar disk image, the phase plane coordinate system requires rotation around the z-axis by an angle ψ and rotation around the x-axis. The angle and the transformation relationship from the phase plane coordinate system to the satellite body coordinate system are given by Q. cb The angle ΔQ that the satellite needs to correct is:

[0023]

[0024] This indicates that the solar disk image rotates about the x-axis according to the phase plane coordinate system. angle;

[0025] Q z (ψ) represents the solar image rotating about the z-axis by an angle ψ according to the phase plane coordinate system.

[0026] Preferably, in step 4, it is assumed that the initial quaternion of the star sensor is Q. bs Then the star-sense mounting matrix correction value ΔQ bs for

[0027]

[0028] One star sensor is selected as the reference star sensor, and this reference star sensor is used for solar imaging. The other star sensors on the satellite are all installed with the modified reference star sensor as a reference.

[0029] Preferably, the solar image is a full solar image or a partial solar image.

[0030] A star sensor mounting correction system based on solar images, according to the present invention, comprises:

[0031] Module M1: Enables the satellite to continuously acquire images of the solar surface using the solar space telescope in steady-state solar observation mode;

[0032] Module M2: Performs edge detection and heliocentric extraction on solar surface images, and performs multi-frame averaging on the centroid coordinates of the solar image;

[0033] Module M3: Based on the solar image and the relationship between the phase plane coordinate system of the solar space telescope and the satellite's body coordinate system, determine the angle that the satellite needs to correct so that the solar image is centered in the field of view;

[0034] Module M4: Calculates the correction value of the star sensor installation matrix based on the satellite correction angle.

[0035] Preferably, in module M2, edge detection is performed using a fitting method. This fitting method first extracts edge points from the solar image using an edge detection algorithm, and then uses the least squares method to fit the edge points to a circle, with the center of the circle being the centroid of the solar image. The edge point coordinates are assumed to be (x1 y1), ..., (x...). N y N N is the number of edge points, (ab) is the coordinate of the center of the circle, R is the radius, and is the true value of the centroid.

[0036] A circle is represented as A(x) 2 +y 2 )+Bx+Cy+D=0, A≠0; (xy) are the coordinates of the edge point;

[0037] The parameters are related as follows:

[0038]

[0039] The objective function F is optimized using the least squares circle fitting method.

[0040]

[0041] To calculate the minimum of the objective function F(A,B,C,D), we differentiate with respect to the circular parameters to obtain estimated values ​​of the parameters. The estimated coordinates of the center of the circle are obtained from the parametric relationship. and radius parameters.

[0042] Preferably, in module M3, the solar disk image needs to be rotated by an angle ψ around the z-axis and by an angle x-axis according to the phase plane coordinate system. The angle and the transformation relationship from the phase plane coordinate system to the satellite body coordinate system are given by Q. cb The angle ΔQ that the satellite needs to correct is:

[0043]

[0044] This indicates that the solar disk image rotates about the x-axis according to the phase plane coordinate system. angle;

[0045] Q z (ψ) represents the solar image rotating about the z-axis by an angle ψ according to the phase plane coordinate system.

[0046] Preferably, in module M4, it is assumed that the initial quaternion of the star sensor is Q. bs Then the star-sense mounting matrix correction value ΔQ bs for

[0047]

[0048] One star sensor is selected as the reference star sensor, and this reference star sensor is used for solar imaging. The other star sensors on the satellite are all installed with the modified reference star sensor as a reference.

[0049] Preferably, the solar image is a full solar image or a partial solar image.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] 1. This invention enables high-precision solar observation, improves solar image quality, and can meet the needs of future space exploration missions.

[0052] 2. This invention is applicable not only to complete solar disk images but also to partial solar disk images. By performing star sensor installation corrections based on partial solar disk images, the problem of high-precision observation by solar space telescopes is solved.

[0053] 3. This invention provides a good technical means for high-precision solar observation of space science satellites and has engineering application value. Attached Figure Description

[0054] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0055] Figure 1 A schematic diagram of the process steps for providing the correction method of the present invention. Detailed Implementation

[0056] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0057] This invention relates to a method for installing and correcting star sensors based on solar images, which can meet the needs of future solar exploration missions and provides a good technical means for high-precision solar observation by space science satellites. This invention is applicable not only to complete full-disk images but also to partial solar images in variations. The following explanation uses a full-disk image as an example.

[0058] like Figure 1 As shown, a star sensor installation correction method based on solar images provided by the present invention includes:

[0059] Step 1: In steady-state solar observation mode, the satellite continuously acquires images of the entire solar disk using the solar space telescope;

[0060] Step 2: For the full solar disk image, edge detection and heliocentric extraction are performed using a fitting method, and the centroid coordinates of the solar image are processed by multi-frame averaging, etc.

[0061] Step 3: Based on the full solar image and the relationship between the phase plane coordinate system of the solar space telescope and the satellite's body coordinate system, determine the angle that the satellite needs to correct to ensure that the solar image is centered in the field of view;

[0062] Step 4: Calculate the correction value of the star sensor installation matrix based on the satellite correction angle to achieve star sensor installation correction based on solar images. Specifically, one star sensor needs to be selected as the reference star sensor, and this reference star sensor is used for full solar imaging. The installation matrix corrections of the remaining star sensors on the satellite are all performed with reference to the corrected reference star sensor.

[0063] In step 2, the fitting method first uses an edge detection algorithm to extract edge points of the solar image, and then uses the least squares method to fit the edge points to a circle, with the center of the circle being the centroid of the solar image. Assume the edge point coordinates are (x1y1), ..., (x... N y N N is the number of edge points. Generally, the equation of a circle can be expressed as:

[0064] (x i -a) 2 +(y i -b) 2 =R 2 i = 1, ..., N

[0065] In the formula, (ab) represents the coordinates of the circle's center, R is the radius, and is the true value of the centroid. A circle can also be represented as A(x... 2 +y 2 ) + Bx + Cy + D = 0, A ≠ 0. (xy) are the coordinates of the edge points. The parameters of these two equations have the following relationship:

[0066]

[0067] The objective function F is optimized using the least squares circle fitting method.

[0068]

[0069] To calculate the minimum of the objective function F(A,B,C,D), we need to differentiate with respect to the circular parameters to obtain their estimated values. The estimated coordinates of the center of the circle can be obtained from the parametric relationship. and radius parameters.

[0070] In step 3, based on the total solar disk image, the phase plane coordinate system requires rotation around the z-axis by an angle of ψ and around the x-axis. The angle and the transformation relationship from the phase plane coordinate system to the satellite body coordinate system are given by Q. cb To ensure the solar image is centered in the field of view, the satellite needs to correct the angle ΔQ as follows:

[0071]

[0072] This indicates that the image of the entire solar disk rotates about the x-axis according to the phase plane coordinate system. angle;

[0073] Q z (ψ) represents the rotation of the solar disk image around the z-axis by an angle ψ according to the phase plane coordinate system.

[0074] In step 4, it is assumed that the initial quaternion of the star sensor is Q. bs Then the star-sense mounting matrix correction value ΔQ bs for

[0075]

[0076] This invention also provides a star sensor installation correction system based on solar images. Those skilled in the art can implement the star sensor installation correction system based on solar images by executing the procedural steps of the method. That is, the method for correcting the star sensor installation based on solar images can be understood as a preferred embodiment of the star sensor installation correction system based on solar images. Specifically, the star sensor installation correction system based on solar images provided by this invention includes:

[0077] Module M1: Enables the satellite to continuously acquire images of the solar surface using the solar space telescope in steady-state solar observation mode;

[0078] Module M2: Performs edge detection and heliocentric extraction on solar surface images, and performs multi-frame averaging on the centroid coordinates of the solar image;

[0079] Module M3: Based on the solar image and the relationship between the phase plane coordinate system of the solar space telescope and the satellite's body coordinate system, determine the angle that the satellite needs to correct so that the solar image is centered in the field of view;

[0080] Module M4: Calculates the correction value of the star sensor installation matrix based on the satellite correction angle.

[0081] Those skilled in the art will understand that, in addition to implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0082] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for installing and correcting a star sensor based on solar images, characterized in that, include: Step 1: In steady-state solar observation mode, the satellite controls the solar space telescope to continuously acquire images of the solar surface; Step 2: For the solar disk image, perform edge detection and heliocentric extraction, and perform multi-frame averaging of the centroid coordinates of the solar image; Step 3: Based on the solar image and the relationship between the phase plane coordinate system of the solar space telescope and the satellite's body coordinate system, determine the angle that the satellite needs to correct so that the solar image is centered in the field of view; Based on the solar disk image, it needs to rotate around the z-axis according to the phase plane coordinate system. Angle, rotation around the x-axis The angle and the transformation relationship from the phase plane coordinate system to the satellite body coordinate system are as follows: The angle that the satellite needs to correct for: This indicates that the solar disk image rotates about the x-axis according to the phase plane coordinate system. angle; This indicates that the solar disk image rotates about the z-axis according to the phase plane coordinate system. angle; Step 4: Calculate the correction value of the star sensor installation matrix based on the satellite correction angle. Assume the initial star sensor installation quaternion is... So, the star-sensor mounting matrix correction value for One star sensor is selected as the reference star sensor, and this reference star sensor is used for solar imaging. The other star sensors on the satellite are all installed with the modified reference star sensor as a reference.

2. The method for installing and correcting a star sensor based on a solar image according to claim 1, characterized in that, In step 2, edge detection is performed using a fitting method. This method first extracts edge points from the solar image using an edge detection algorithm, and then uses the least squares method to fit a circle to the edge points. The center of this circle is the centroid of the solar image. Assuming the coordinates of the edge points are... , ..., N is the number of edge points. Let the coordinates be the center of the circle. R Let be the radius, which is the true value of the centroid we are looking for; Circle is represented as , ; These are the coordinates of the edge points; The parameters are related as follows: ， ， The objective function F is optimized using the least squares circle fitting method. ， To calculate the objective function The minimum value is obtained by differentiating the circle parameters with respect to them, thus yielding an estimate of the parameters. The estimated coordinates of the center of the circle are obtained through the parametric relationship. and radius parameters.

3. The method for installing and correcting a star sensor based on a solar image according to claim 1, characterized in that, The solar image can be a full solar image or a partial solar image.

4. A star sensor mounting and correction system based on solar images, characterized in that, include: Module M1: Enables the satellite to continuously acquire images of the solar surface using the solar space telescope in steady-state solar observation mode; Module M2: Performs edge detection and heliocentric extraction on solar surface images, and performs multi-frame averaging on the centroid coordinates of the solar image; Module M3: Based on the solar image and the relationship between the phase plane coordinate system of the solar space telescope and the satellite's body coordinate system, determine the angle that the satellite needs to correct so that the solar image is centered in the field of view; Based on the solar disk image, it needs to rotate around the z-axis according to the phase plane coordinate system. Angle, rotation around the x-axis The angle and the transformation relationship from the phase plane coordinate system to the satellite body coordinate system are as follows: The angle that the satellite needs to correct for: This indicates that the solar disk image rotates about the x-axis according to the phase plane coordinate system. angle; This indicates that the solar disk image rotates about the z-axis according to the phase plane coordinate system. angle; Module M4: Calculates the correction value of the star sensor installation matrix based on the satellite correction angle, assuming the initial star sensor installation quaternion is... So, the star-sensor mounting matrix correction value for One star sensor is selected as the reference star sensor, and this reference star sensor is used for solar imaging. The other star sensors on the satellite are all installed with the modified reference star sensor as a reference.

5. The star sensor mounting and correction system based on solar images according to claim 4, characterized in that, In module M2, edge detection is performed using a fitting method. This method first extracts edge points from the solar image using an edge detection algorithm, and then uses the least squares method to fit a circle to the edge points. The center of this circle is the centroid of the solar image. Assuming the coordinates of the edge points are... , ..., N is the number of edge points. Let the coordinates be the center of the circle. R Let be the radius, which is the true value of the centroid we are looking for; Circle is represented as , ; These are the coordinates of the edge points; The parameters are related as follows: ， ， The objective function F is optimized using the least squares circle fitting method. ， To calculate the objective function The minimum value is obtained by differentiating the circle parameters with respect to them, thus yielding an estimate of the parameters. The estimated coordinates of the center of the circle are obtained through the parametric relationship. and radius parameters.

6. The star sensor mounting and correction system based on solar images according to claim 4, characterized in that, The solar image can be a full solar image or a partial solar image.

Images