Satellite attitude collaborative calibration method based on inter-satellite link for Internet constellation

Abstract

The invention provides an inter-satellite link-based satellite attitude collaborative calibration method for an internet constellation. The method comprises the following steps: acquiring data of node satellites and adjacent satellites; calculating a link inertia vector in an ideal state through the orbit vector; calculating an attitude estimation value according to a relation between a link inertia vector and an actual link vector in an ideal state; when the satellite attitude sensor works normally, correcting the estimated attitude based on the error attitude correction amount; and completing the alignment or alignment optimization of the link according to the satellite attitude after attitude estimation or correction. According to the method, the attitude estimation matrix is calculated through pseudo-inverse solution and orthogonal optimization by utilizing the relationship between the theoretical inertia vector and the actual load vector of the inter-satellite link, the attitude is determined by utilizing the inter-satellite link multi-vector joint of the adjacent satellites, the attitude error is calibrated through the link vector when the attitude sensor is effective, and the attitude calibration precision is improved; and when the attitude sensor fails, reliable attitude estimation and maintenance functions are provided through link assistance.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite attitude estimation, and in particular to an inter-satellite link-based satellite attitude collaborative calibration method for an Internet constellation. Background Art

[0002] In recent years, low-orbit Internet satellite constellations have gradually become a hot spot in the global communications field. Low-orbit satellite constellations provide low-latency, high-bandwidth communication services to global users by deploying a large number of low-orbit satellites. In order to achieve stable communication between satellites, laser links (intersatellite links) between low-orbit satellites are widely used. Precise control of satellite attitude is crucial to the alignment and communication quality of intersatellite links, because the high-speed movement and orbit changes of satellites can cause attitude errors, which in turn affect the stability of the link and communication efficiency. Therefore, satellite constellations need to perform high-precision attitude calibration corrections regularly to ensure the alignment of laser links.

[0003] Existing satellite attitude correction methods mainly rely on satellite attitude sensors (such as star sensors, gyroscopes, etc.) and ground measurement and control instructions. However, these methods have certain limitations when facing a large number of low-orbit satellites and complex operating environments. Existing satellite attitude calibration technologies have the following main disadvantages:

[0004] 1) Limitations of relying on onboard sensors

[0005] Single-satellite attitude determination methods usually rely on onboard sensors (such as star sensors, gyroscopes, etc.), but these sensors have measurement errors and drift problems. When the star sensor fails, it is difficult to maintain high accuracy for the single-satellite attitude, which directly affects the alignment accuracy of the laser link.

[0006] 2) High dependence on ground measurement and control

[0007] Traditional satellite attitude calibration methods usually rely on the measurement and control instructions of ground stations to correct the satellite's attitude. However, due to the large number of satellites in low-orbit constellations and short orbital periods, it is difficult for ground stations to efficiently cover and perform attitude calibration in real time, resulting in delays and poor timeliness. This method is particularly unsuitable in low-orbit constellations and cannot meet the needs of real-time and efficient attitude correction.

[0008] 3) Lack of multi-satellite collaborative calibration mechanism

[0009] Whether it is based on the data of a single satellite attitude sensor or the ground-based calibration method, neither fully utilizes the attitude data of other satellites in the constellation for collaborative calibration. In the existing technology, intersatellite links are mainly used for data transmission, and fail to effectively utilize the attitude information of multiple satellites in the constellation for collaborative work, resulting in the lack of an efficient attitude error correction mechanism. Summary of the invention

[0010] In view of the deficiencies in the prior art, the present invention provides a satellite attitude collaborative calibration method based on inter-satellite links for an Internet constellation. The present invention utilizes the inter-satellite link multi-vector joint attitude determination of adjacent satellites. When the attitude sensor is effective, the attitude error is calibrated by the link vector to improve the attitude calibration accuracy. When the attitude sensor fails, reliable attitude estimation and maintenance functions are provided through link assistance.

[0011] The technical solution of the present invention is: a satellite attitude collaborative calibration method based on inter-satellite links for an Internet constellation, comprising the following steps:

[0012] S1), obtain node satellite and adjacent satellite data;

[0013] S2), calculating the link inertia vector under ideal conditions through the orbit vector;

[0014] S3), calculating the attitude estimation value through the relationship between the link inertia vector under the ideal state and the actual link vector;

[0015] S4), when the satellite attitude sensor works normally, correct the estimated attitude based on the error attitude correction amount;

[0016] S5) According to the attitude estimation or correction of the completed satellite attitude, the alignment or alignment optimization of the link is completed.

[0017] Preferably, in step S1), a link is established in a cross configuration, and the acquired data of the node satellite and the adjacent satellite include: satellite orbit position, link load optical axis vector, and satellite's own attitude data.

[0018] Preferably, in step S2), the calculation formula of the link inertia vector under the ideal state is:

[0019]

[0020] In the formula, l i-1，i eci For S i-1，j Point to S i，j The link inertia vector, l i+1，i eci For S i+1，j Point to S i，j The link inertia vector, l j-1，j eci For S i，j-1 Point to S i，j The link inertia vector, l j+1，j eci For S i，j+1 Point to S i，j The link inertia vector of the satellite S i，j, i is the orbital plane number, j is the satellite number in the orbital plane; S i-1，j , S i+1，j , S i，j-1 , S i，j+1 Satellite S i，j Adjacent satellites; r i，j Satellite S i，j The orbital position of r i-1，j 、r i+1，j 、r i，j-1 、r i，j+1 Satellite S i-1，j , S i+1，j , S i，j-1 , S i，j+1 The orbital position of the object; the superscript b indicates the body coordinate system; the superscript eci indicates the inertial coordinate system.

[0021] Preferably, in step S3), the attitude estimation value is calculated by the relationship between the link inertia vector under an ideal state and the actual link vector, which specifically includes the following steps:

[0022] S31), the relationship between the link inertia vector and the actual link vector in the ideal state is expressed as:

[0023] L b =A kj L eci (1);

[0024] Where, L b is the actual link vector matrix in this system; L eci A is the link inertia vector matrix under ideal conditions; kj is the attitude estimation matrix; the subscript kj represents the index of the attitude estimation matrix;

[0025] S32), construct the pseudo-inverse solution formula (1) by minimizing the error square sum, and obtain the inverse solution matrix A * :

[0026] A * =L b (L eci ) T (L eci (L eci ) T ) -1 (2);

[0027] In the formula, A * represents the inverse solution matrix; (L eci ) T It represents the link inertia vector matrix L under ideal conditions eci The transposed matrix of ; T represents the transposed operation;

[0028] S33), inverse solution matrix A * Orthogonalization is performed to satisfy the orthogonal constraints of the rotation matrix, and the final attitude estimation matrix A is optimized. kj ;

[0029] S34), the final posture estimation matrix A kj Convert to estimated attitude quaternion

[0030] Preferably, in step S4), the estimated posture is corrected based on the error posture correction amount, which specifically includes the following steps:

[0031] S41), combining the laser load error and the attitude error into a correction value Q e ;

[0032] S42), based on the error attitude correction value Q e Estimated attitude quaternion Make corrections to obtain the corrected satellite attitude quaternion

[0033] Preferably, in step S5), when the attitude sensor fails, the attitude quaternion is estimated using Maintain alignment of the laser link.

[0034] Preferably, in step S5), when the attitude sensor is effective, the corrected satellite attitude quaternion The input control system further adjusts the attitude to achieve link alignment optimization.

[0035] The beneficial effects of the present invention are:

[0036] 1. The present invention utilizes the relationship between the theoretical inertia vector and the actual load vector of the intersatellite link, constructs a high-precision attitude estimation matrix through pseudo-inverse solution and orthogonal optimization, and further converts it into a quaternion for attitude correction;

[0037] 2. The present invention makes full use of inter-satellite link vector information to provide a reliable auxiliary mechanism for attitude estimation, which can ensure high attitude accuracy even in complex environments or when sensor errors increase;

[0038] 3. The present invention estimates the attitude of the target satellite through orbit vector and link load information, combined with the attitude and orbit data of adjacent satellites, to ensure the alignment and communication stability of the laser link in the short term;

[0039] 4. The present invention constructs a distributed attitude calibration architecture through the synergy of multiple satellites. When the star sensor is effective, the sensor error is corrected through link attitude estimation; when it fails, the attitude reference of the target satellite is maintained through multi-satellite collaboration;

[0040] 5. The present invention adopts an optimization mechanism of minimizing the sum of squares of link errors in a distributed architecture. By comprehensively balancing the link performance, it effectively avoids the situation where some links have better alignment effects while other links have poor alignment effects during the system calibration process. This balanced optimization feature ensures the overall accuracy of the target satellite attitude and the consistency of the link performance, and significantly improves the overall stability of the link.

[0041] 6. The distributed architecture of the present invention is more robust in calibration accuracy and link alignment effect, and is particularly suitable for high-dynamic environments such as low-orbit constellations. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the process of the present invention;

[0043] Figure 2 The figure is a schematic diagram of a satellite cross-configuration intersatellite link according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

[0045] like Figure 1 As shown, this embodiment provides a satellite attitude collaborative calibration method based on an inter-satellite link for an Internet constellation, comprising the following steps:

[0046] S1), obtain node satellite and adjacent satellite data;

[0047] This embodiment uses the multi-vector joint attitude determination of the inter-satellite links of adjacent satellites, such as Figure 2 As shown, in this embodiment, when the link is established in a cross configuration, the satellite S i，j The adjacent satellites are S i-1，j , S i+1，j , S i，j-1 , S i，j+1 .

[0048] The satellite data acquired in this embodiment includes: orbital position, link load optical axis vector, and satellite's own attitude data.

[0049] The node satellite obtains the satellite's orbital vector r in the inertial system according to its own orbit, and obtains the orbital vector of the adjacent satellite through the intersatellite link, and obtains the payload optical axis vector matrix of the satellite in this system, that is, the actual link vector matrix L b :

[0050] L b =[p i，i-1 b p j，j-1 b p i，i+1b p j，j+1 b ];

[0051] in,

[0052]

[0053]

[0054] In the formula, Q = [q 0 ,q 1 ,q 2 ,q 3 ] T represents the satellite attitude inertial quaternion; the superscript T represents the transposition operator; the superscript b represents the body coordinate system; the superscript eci represents the inertial coordinate system; q 0 ,q 1 ,q 2 ,q 3 Represents each element of the quaternion; o represents the rotation operation of the quaternion and the vector; subscript i is the orbital plane number, and subscript j is the satellite number in the orbital plane;

[0055] When the satellite's attitude sensor (such as a star sensor) works normally, the satellite's own attitude data is obtained. S2) Calculate the link inertia vector under the ideal state through the orbit vector; the calculation formula is:

[0056]

[0057] In the formula, l i-1，i eci For S i-1，j Point to S i，j The link inertia vector, l i+1，i eci For S i+1，j Point to S i，j The link inertia vector, l j-1，j eci For S i，j-1 Point to S i，j The link inertia vector, l j+1，j eci For S i，j+1 Point to S i，j The link inertia vector of the satellite S i，j , i is the orbital plane number, j is the satellite number in the orbital plane; S i-1，j , S i+1，j , S i，j-1 , S i，j+1 Satellite S i，j Adjacent satellites; r i，j Satellite S i，j The orbital position of ri-1，j 、r i+1，j 、r i，j-1 、r i，j+1 Satellite S i-1，j , S i+1，j , S i，j-1 , S i，j+1 The orbital position of the object; the superscript b indicates the body coordinate system; the superscript eci indicates the inertial coordinate system.

[0058] S3), calculating the attitude estimation value through the relationship between the link inertia vector under the ideal state and the actual link vector; specifically comprising the following steps:

[0059] S31), the relationship between the link inertia vector and the actual link vector in the ideal state is expressed as:

[0060] L b =A kj L eci (1);

[0061] Where, L b is the actual link vector matrix in this system; L eci A is the link inertia vector matrix under ideal conditions; kj is the attitude estimation matrix; the subscript kj represents the index of the attitude estimation matrix.

[0062] in,

[0063] L b =[p i，i-1 b p j,j-1 b p i,i+1 b p j，j+1 b ];

[0064] L eci =[l i-1，i eci l j-1，j eci l i+1，i eci l j+1，j eci ];

[0065] S32), construct the pseudo-inverse solution formula (1) by minimizing the error square sum, and obtain the inverse solution matrix A * :

[0066] A * =L b (L eci ) T (L eci (Leci ) T ) -1 (2);

[0067] In the formula, A * represents the inverse solution matrix; (L eci ) T It represents the link inertia vector matrix L under ideal conditions eci The transposed matrix of

[0068] S33), inverse solution matrix A * Orthogonalization is performed to satisfy the orthogonal constraints of the rotation matrix, and the final attitude estimation matrix A is optimized. kj ;

[0069]

[0070] In the formula, a 11 ~a 33 Represents the 3x3 matrix A respectively kj Each element of; I represents the 3x3 identity matrix;

[0071] S34), the final posture estimation matrix A kj Convert to estimated attitude quaternion

[0072]

[0073] The quaternion solution formula is as follows:

[0074]

[0075] Based on the first line of equations (7)-(10), q is calculated respectively 0 ,q 1 ,q 2 ,q 3 , compare q 0 ,q 1 ,q 2 ,q 3 The absolute value of the maximum absolute value is selected to calculate the estimated posture.

[0076] S4), when the satellite attitude sensor works normally, the estimated attitude is corrected based on the error attitude correction amount; specifically comprising the following steps:

[0077] S41), combining the laser load error and the attitude error into the error attitude correction value Q e ; The error attitude correction Q e The expression is:

[0078]

[0079] In the formula, Represents quaternions Every element of Q s The attitude quaternion determined by the satellite attitude sensor; To estimate the pose;

[0080] S42), based on the error attitude correction value Q e Estimated attitude quaternion Make corrections to obtain the corrected satellite attitude quaternion Right now:

[0081]

[0082] Where W e is the error attitude correction; W s The attitude quaternion determined by the satellite attitude sensor.

[0083] S5) According to the attitude estimation or correction of the completed satellite attitude, the alignment or alignment optimization of the link is completed.

[0084] In this embodiment, when the attitude sensor fails, the estimated attitude quaternion is used Maintain alignment of the laser link.

[0085] When the attitude sensor is valid, the corrected satellite attitude quaternion The input control system further adjusts the attitude to achieve link alignment optimization.

[0086] The above embodiments and descriptions are only for illustrating the principles and best embodiments of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, all of which fall within the scope of the present invention to be protected.

Claims

1. A satellite attitude collaborative calibration method based on inter-satellite links for an Internet constellation, characterized in that: The following steps are involved: S1), obtain node satellite and adjacent satellite data; S2), calculating the link inertia vector under ideal conditions through the orbit vector; S3), calculating the satellite attitude estimation value through the relationship between the link inertia vector under the ideal state and the actual link vector; S4), when the satellite attitude sensor works normally, correct the satellite estimated attitude based on the error attitude correction amount; S5) According to the attitude estimation or correction of the completed satellite attitude, the alignment or alignment optimization of the link is completed.

2. The satellite attitude collaborative calibration method based on inter-satellite links for an Internet constellation according to claim 1, characterized in that: In step S1), a link is established in a cross configuration, and the acquired data of the node satellite and the adjacent satellite include: satellite orbit position, link load optical axis vector, and satellite attitude data.

3. The satellite attitude collaborative calibration method based on inter-satellite links for an Internet constellation according to claim 1, characterized in that: In step S2), the calculation formula of the link inertia vector under the ideal state is: In the formula, l i-1,i eci For S i-1,j Point to S i,j The link inertia vector, l i+1,i eci For S i+1,j Point to S i,j The link inertia vector, l j-1,j eci For S i,j-1 Point to S i,j The link inertia vector, l j+1,j eci For S i,j+1 Point to S i,j The link inertia vector of the satellite S i,j , i is the orbital plane number, j is the satellite number in the orbital plane; S i-1,j , S i+1,j , S i,j-1 , S i,j+1 Satellite S i,j Adjacent satellites; r i,j Satellite S i,j The orbital position of r i-1,j 、r i+1,j 、r i,j-1 、r i,j+1 Satellite S i-1,j , S i+1,j , S i,j-1 , S i,j+1 The orbital position of the object; the superscript b indicates the body coordinate system; the superscript eci indicates the inertial coordinate system.

4. The satellite attitude collaborative calibration method based on inter-satellite links for an Internet constellation according to claim 3, characterized in that: In step S3), the attitude estimation value is calculated by the relationship between the link inertia vector under the ideal state and the actual link vector, which specifically includes the following steps: S31), the relationship between the link inertia vector and the actual link vector in the ideal state is expressed as: L b =A kj L eci (1); Where, L b is the actual link vector matrix in this system; L eci A is the link inertia vector matrix under ideal conditions; kj is the attitude estimation matrix, and the subscript kj represents the index of the attitude estimation matrix; S32), construct the pseudo-inverse solution formula (1) by minimizing the error square sum, and obtain the inverse solution matrix A * : A *L b (L eci ) T (L eci (L eci ) T ) -1 (2); In the formula, A * represents the inverse solution matrix; (L eci ) T Represents the link inertia vector matrix L under ideal conditions eci The transposed matrix of , T represents the transposed operation; S33), inverse solution matrix A * Orthogonalization is performed to satisfy the orthogonal constraints of the rotation matrix, and the final attitude estimation matrix A is optimized. kj ; S34), the final posture estimation matrix A kj Convert to estimated attitude quaternion 5. The satellite attitude collaborative calibration method based on inter-satellite links for an Internet constellation according to claim 4, characterized in that: In step S33), the final posture estimation matrix A kj The expression is: In the formula, a 11 ~a 33 Represents the 3x3 matrix A respectively kj Each element of; I represents the 3x3 identity matrix.

6. The satellite attitude collaborative calibration method based on inter-satellite links for an Internet constellation according to claim 5, characterized in that: In step S34), the estimated attitude quaternion It is expressed as: The quaternion solution formula is as follows: Based on the first line of equations (7)-(10), q0, q1, q2, q3 are calculated respectively, and the absolute values ​​of q0, q1, q2, q3 are compared. The formula corresponding to the largest absolute value is selected to calculate the estimated posture.

7. The satellite attitude collaborative calibration method based on inter-satellite links for an Internet constellation according to claim 6, characterized in that: In step S4), the estimated attitude is corrected based on the error attitude correction amount, which specifically includes the following steps: S41), combining the laser load error and the attitude error into the error attitude correction value Q e ; S42), based on the error posture correction value W e Estimated attitude quaternion Make corrections to obtain the corrected satellite attitude quaternion 8. The satellite attitude collaborative calibration method based on inter-satellite links for an Internet constellation according to claim 7, characterized in that: In step S41), the error attitude correction value W e It is expressed as: In the formula, Represents quaternions Each element of W s The attitude quaternion determined by the satellite attitude sensor; To estimate the pose; In step S42), the corrected satellite attitude quaternion It is expressed as: Where W e is the error attitude correction; Q s The attitude quaternion determined by the satellite attitude sensor.

9. The satellite attitude collaborative calibration method based on inter-satellite links for an Internet constellation according to claim 1, characterized in that: In step S5), when the attitude sensor fails, the attitude quaternion is estimated using Maintain alignment of the laser link.

10. The satellite attitude collaborative calibration method based on inter-satellite links for an Internet constellation according to claim 9, characterized in that: In step S5), when the attitude sensor is valid, the corrected satellite attitude quaternion The input control system further adjusts the attitude to achieve link alignment optimization.

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