Rapid calibration method for multi-star-sensor installation matrix of low-orbit moonlet

Abstract

The invention discloses a quick calibration method for a multi-star-sensor installation matrix of a low-orbit moonlet, and belongs to the technical field of satellite star sensor calibration. The method comprises the following steps: firstly, selecting star sensor observation four-element data of a multi-track most common star sensor combination, and recording the most common star sensor combination as a first star sensor and a second star sensor; taking a first star sensor installation matrix given by a satellite as a reference to obtain an installation matrix of a second star sensor at each calibration moment, and performing adjustment processing to obtain a second star sensor installation matrix after adjustment; selecting other star sensors combined with the first star sensor or the second star sensor, and carrying out calibration and adjustment processing on the uncalibrated star sensor installation matrix to obtain an adjusted star sensor installation matrix; and gradually expanding the range of the star sensors in this way, and finally obtaining and outputting all installation matrixes after star sensor adjustment. According to the method, high-precision geometric calibration can be rapidly completed, and support is provided for rapidly exerting application efficiency after the remote sensing satellite is launched.

Description

Technical Field

[0001] The invention relates to a method for quickly calibrating a multi-star-sensor installation matrix of a low-orbit small satellite, and belongs to the technical field of satellite star-sensor calibration. Background Art

[0002] In order to give full play to the application efficiency of low-orbit small satellite constellation data, the low-orbit small satellite constellation images are required to have high radiation and geometric quality.

[0003] The geometric quality of remote sensing images is mainly reflected in the geometric positioning accuracy of the images. Constellation cluster remote sensing satellites are launched with multiple satellites at a time. In order for the constellation cluster remote sensing satellites to quickly exert their application efficiency, the satellites need to have high-precision attitude determination capabilities in terms of geometry, and they also need to be able to quickly complete high-precision geometric calibration after launch. The satellite itself has high-precision attitude determination capabilities by being equipped with multiple star sensors (usually 3-4) and gyro systems for high-precision attitude measurement. However, in order to obtain high-precision attitude data during ground processing, the ground processing system also needs to use the star sensor and gyro measurement data transmitted by the satellite for attitude determination processing to obtain high-precision satellite attitude data, thereby completing the camera geometry calibration and high-precision geometry correction production of subsequent products.

[0004] Since the observation data of effective star sensors may be part of the agile imaging of low-orbit small satellites (at least 2), it is necessary to quickly calibrate the installation matrix of each star sensor to achieve consistent accuracy of attitude determination results of any star sensor combination. When transmitting the attitude measurement results of multiple star sensors, most satellites choose to only transmit the attitude measurement data of two of the star sensors. The star sensor measurement data transmitted at different times may be different star sensor combinations, resulting in the need for the ground processing system to use different star sensor combinations for attitude determination.

[0005] Since errors exist in the installation matrices of each star sensor, the accuracy of attitude determination results of different star sensor combinations is inconsistent. To solve this problem, the existing ground processing system has a solution of performing geometric calibration of the calibration field for different star sensor combinations, obtaining geometric calibration parameters of different star sensor combination states, and selecting corresponding parameters according to the star sensor combination state during geometric correction processing; the second solution is to obtain the geometric calibration field imaging data under different star sensor combinations, use the geometric calibration field control points to solve the true attitude of the satellite (or camera), and then use the true attitude to calibrate the installation matrix of each star sensor. The calibrated star sensor installation matrix is ​​used during geometric calibration processing, and any dual star sensor attitude determination can obtain attitude results with consistent accuracy.

[0006] Both of the above solutions require ground calibration field imaging and calibration processing under different star sensitivity combinations. The calibration process is complex and takes a long time. Summary of the invention

[0007] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, and to propose a method for quickly calibrating the installation matrix of multiple star sensors for a low-orbit small satellite, wherein the initial installation matrix of one star sensor among multiple star sensors is selected as a reference, and the installation matrices of other star sensors are calibrated, so that any combination of star sensors can be used for attitude determination processing to obtain attitude determination results with consistent accuracy.

[0008] The technical solution of the present invention is:

[0009] A method for rapid calibration of a multi-satellite sensitive installation matrix for a low-orbit small satellite, comprising:

[0010] S1: For the satellite to be calibrated, select the four-element data of the most commonly used star-sensitivity combination in multiple orbits, and record the most commonly used star-sensitivity combination as the first star-sensitivity and the second star-sensitivity;

[0011] S2: Based on the first star sensor installation matrix provided by the satellite, and based on the four-element data of the star sensor observation of the most commonly used star sensor combination of multiple tracks, the second star sensor installation matrix at different calibration times is calibrated to obtain the installation matrix of the second star sensor at the calibration time; based on the installation matrix of the second star sensor at each calibration time, an adjustment process is performed to obtain the adjusted second star sensor installation matrix;

[0012] S3: Select other star sensors combined with the first star sensor or the second star sensor to obtain the combined multi-track star sensor observation four-element data; for the data of each track star sensor combination, use the known or calibrated star sensor in the combination as a reference to calibrate the uncalibrated star sensor installation matrix to obtain the installation matrix of the star sensor at the calibration time; perform adjustment processing based on the installation matrix of the star sensor at each calibration time to obtain the adjusted star sensor installation matrix;

[0013] Select a known or calibrated star sensor combination again, and obtain the installation matrix of the unknown star sensor through the above method; gradually expand the star sensor range in this way, and finally obtain the installation matrix after all star sensors are adjusted;

[0014] S4: Output the installation matrices of all other star sensors after calibration based on the first star sensor installation matrix.

[0015] Furthermore, in step S2, the second star-sensing installation matrix is ​​calibrated based on the first star-sensing installation matrix provided by the satellite, and the specific method is as follows:

[0016] The attitude matrices of the satellite bodies of the two star-sensing structures in the inertial system are equal, that is, the following formula holds:

[0017] R -1 BS1 ·R S1 =R -1 BS2 ·R S2

[0018] Where: R -1 BS1 is the inverse matrix of the installation matrix of the first star sensor in the satellite body, R -1 BS2 is the inverse matrix of the installation matrix of the second star sensor in the satellite body; R S1 is the attitude matrix of the first star sensor in the inertial system, R S2 is the attitude matrix of the second star sensor in the inertial system, obtained from the four elements of the star sensor at the same time;

[0019] When the first star sensor installation matrix is ​​known, the inverse matrix of the second star sensor installation matrix is ​​obtained:

[0020] R -1 BS2 =R -1 BS1 ·R S1 R -1 S2

[0021] Based on this, the installation matrix of the second star sensor at the calibration time is obtained:

[0022] R BS2 =[R -1 BS1 ·R S1 R -1 S2 ] -1 .

[0023] Furthermore, R S1 and R S2 Obtained from the four elements of star sensitivity at the same time;

[0024] R Si [0][0] = q i0 ×q i0 +q i1 ×q i1 -q i2 ×q i2 -q i3 ×q i3

[0025] R Si [0][1] = 2 × (q i1 ×q i2 -q i0 ×q i3 )

[0026] R Si [0][2] = 2 × (q i1 ×q i3 +q i0 ×q i2 )

[0027] R Si [1][0] = 2 × (q i2 ×q i1 +q i0 ×q i3 )

[0028] R Si [1][1] = q i0 ×q i0 -q i1 ×q i1 +q i2 ×q i2 -q i3 ×q i3

[0029] R Si [1][2] = 2 × (q i2 ×q i3 -q i0 ×q i1 )

[0030] R Si [2][0] = 2 × (q i1 ×q i3 -q i0 ×q i2 )

[0031] R Si [2][1]=2×(q i2 ×q i3 +q i0 ×q i1 )

[0032] R Si [2][2]=q i0 ×q i0 -q i1 ×q i1 -q i2 ×q i2 +q i3 ×q i3

[0033] In the formula, [q i0 q i1 q i2 q i3 ] is the quaternion of the i-th star at the same moment.

[0034] Furthermore, in step S2, the second star sensor installation matrix after adjustment is:

[0035]

[0036] in: is the final calibration result of the second star sensor installation matrix after adjustment; j is the time point sequence number; R BS2j is the installation matrix result of the second star sensitivity at the jth time point; N is the total number of calibration points.

[0037] Furthermore, in step S3, the mth star sensor installation matrix after adjustment is obtained as:

[0038]

[0039] in: is the final calibration result of the mth star sensor installation matrix after adjustment; j is the time point sequence number; R BSmj is the installation matrix result of the mth star sensitivity at the jth time point; M is the total number of calibration points.

[0040] The advantages of the present invention compared with the prior art are:

[0041] The present invention adopts the star sensor observation data of multi-orbit commonly used star sensor combinations and uncommon star sensor combinations to quickly complete the star sensor installation matrix calibration, overcoming the shortcoming that the traditional star sensor calibration method needs to spend a lot of time to complete, and does not require ground calibration field imaging and calibration processing, so as to obtain accurate and stable and reliable attitude determination results for any star sensor combination, and provide support for quickly completing high-precision geometric calibration and quickly exerting the application efficiency of the remote sensing satellite after launch. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0043] Figure 1 This is a flow chart of a method for rapid calibration of a multi-star sensitive installation matrix of a low-orbit small satellite according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0045] The present invention proposes a method for rapid calibration of a multi-star sensor installation matrix of a low-orbit small satellite, taking a satellite with three star sensors installed as an example. Figure 1 As shown, the specific steps include:

[0046] S1: For a specific satellite, select the four-element data of the star-sensitivity observation of the commonly used star-sensitivity combination of multiple tracks (take the commonly used star-sensitivity combination of star-sensitivity 1 / 2 as an example). The purpose of selecting multi-track data is to perform adjustment processing for the subsequent steps in order to eliminate the influence of random observation errors.

[0047] S2: Based on the installation matrix of star sensor 1 provided by the satellite, the installation matrix of star sensor 2 is calibrated. The attitude matrices of the satellite bodies of the two star sensors in the inertial system should be equal, that is, the following formula holds true:

[0048] R -1 BS1 ·R S1 =R -1 BS2 ·R S2

[0049] Where: R -1 BS1 is the inverse matrix of the installation matrix of Xingmin 1 in the satellite body, R -1 BS2 is the inverse matrix of the installation matrix of Xingmin 2 in the satellite body, R S1 is the attitude matrix of the star sensor in the inertial system, R S2 is the attitude matrix of Xingmin 2 in the inertial system. S1 and R S2 The four star-sensing elements at the same time are constructed according to the following formula:

[0050] R S [0][0]=q0×q0+q1×q1-q2×q2-q3×q3

[0051] R S [0][1] = 2 × (q1 × q2 - q0 × q3)

[0052] R S [0][2] = 2 × (q1 × q3 + q0 × q2)

[0053] R S [1][0] = 2 × (q2 × q1 + q0 × q3)

[0054] R S [1][1] = q0 × q0 - q1 × q1 + q2 × q2 - q3 × q3

[0055] R S [1][2] = 2 × (q2 × q3 - q0 × q1)

[0056] R S [2][0] = 2 × (q1 × q3 - q0 × q2)

[0057] R S [2][1] = 2 × (q2 × q3 + q0 × q1)

[0058] R S [2][2] = q0 × q0 - q1 × q1 - q2 × q2 + q3 × q3

[0059] When the installation matrix of Star Sensor 1 is known, the inverse matrix of the installation matrix of Star Sensor 2 can be obtained as follows:

[0060] R -1 BS2 =R -1 BS1 ·R S1 R -1 S2

[0061] Based on this, the installation matrix of StarMin 2 at a certain calibration time can be obtained:

[0062] R BS2 =[R -1 BS1 ·R S1 R -1 S2 ] -1

[0063] The calibration results of the multi-track data are adjusted to obtain the installation matrix of the StarMin 2 after adjustment:

[0064]

[0065] in: is the final calibration result of the second star sensor installation matrix after adjustment; j is the time point sequence number; R BS2j is the installation matrix result of the second star sensitivity at the jth time point; N is the total number of calibration points.

[0066] S3: Select the four-element data of the star-sensitivity observation of the multi-orbit uncommon star-sensitivity combination (star-sensitivity 1 / 3 combination and star-sensitivity 2 / 3 combination);

[0067] For the data of the unused star sensor combination of each orbit, the third star sensor installation matrix is ​​calibrated with star sensor 1 or the calibrated star sensor 2 as the benchmark. The calibration method is basically the same as step S2, and the result is:

[0068] R BS3 =[R -1 BS1 ·R S1 R -1 S3 ] -1 or

[0069] The multi-track data is used to obtain the point star-sensing 3 installation matrix for adjustment processing, and the adjusted star-sensing 3 installation matrix is ​​obtained:

[0070]

[0071] in: is the final calibration result of the three-star sensitive installation matrix after adjustment; j is the sequence number of the time point; R BS3j is the installation matrix result of the third star sensitivity at the jth time point; M is the total number of calibration points.

[0072] S4: Output the installation matrix of star sensor 2 and star sensor 3 after calibration based on the installation matrix of star sensor 1. Up to this point, the original installation matrix of the star sensor selected as the reference is included, that is, the installation matrix of all star sensors after calibration.

[0073] The present invention proposes a method for rapid calibration of a multi-star-sensor installation matrix for low-orbit small satellites, which overcomes the traditional method of using ground calibration field imaging to accurately calibrate the star-sensor installation matrix, which requires a lot of time to obtain calibration field data and complex calibration processing. It can achieve consistent attitude data accuracy for attitude determination with any combination of star sensors, and provide support for rapid geometric calibration of low-orbit small satellite constellations and the realization of application efficiency.

[0074] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for rapid calibration of a multi-satellite sensor installation matrix for a low-orbit small satellite, characterized in that: include: S1: For the satellite to be calibrated, select the four-element data of the most commonly used star-sensitivity combination in multiple orbits, and record the most commonly used star-sensitivity combination as the first star-sensitivity and the second star-sensitivity; S2: Taking the first star sensor installation matrix provided by the satellite as the benchmark, based on the star sensor observation four-element data of the most commonly used star sensor combination of multiple orbits, calibrate the second star sensor installation matrix at different calibration times to obtain the installation matrix of the second star sensor at the calibration time; Based on the installation matrix of the second star sensor at each calibration time, an adjustment process is performed to obtain the installation matrix of the second star sensor after adjustment; S3: Select other star sensors combined with the first star sensor or the second star sensor to obtain the combined multi-track star sensor observation four-element data; for the data of each track star sensor combination, use the known or calibrated star sensor in the combination as a reference to calibrate the uncalibrated star sensor installation matrix to obtain the installation matrix of the star sensor at the calibration time; perform adjustment processing based on the installation matrix of the star sensor at each calibration time to obtain the adjusted star sensor installation matrix; Select a known or calibrated star sensor combination again, and obtain the installation matrix of the unknown star sensor through the above method; gradually expand the star sensor range in this way, and finally obtain the installation matrix after all star sensors are adjusted; S4: Output the installation matrices of all other star sensors after calibration based on the first star sensor installation matrix.

2. The method for rapid calibration of a multi-satellite sensitive installation matrix of a low-orbit small satellite according to claim 1, characterized in that: In step S2, the second star-sensing installation matrix is ​​calibrated based on the first star-sensing installation matrix provided by the satellite. The specific method is as follows: The attitude matrices of the satellite bodies of the two star-sensing structures in the inertial system are equal, that is, the following formula holds: R -1 BS1 ·R S1 =R -1 BS2 ·R S2 Where: R -1 BS1 is the inverse matrix of the installation matrix of the first star sensor in the satellite body, R -1 BS2 is the inverse matrix of the installation matrix of the second star sensor in the satellite body; R S1 is the attitude matrix of the first star sensor in the inertial system, R S2 is the attitude matrix of the second star sensor in the inertial system, obtained from the four elements of the star sensor at the same time; When the first star sensor installation matrix is ​​known, the inverse matrix of the second star sensor installation matrix is ​​obtained: R -1 BS2 =R -1 BS1 ·R S1 R -1 S2 Based on this, the installation matrix of the second star sensor at the calibration time is obtained: R BS2 =[R -1 BS1 ·R S1 R -1 S2 ] -1 。 3. The method for rapid calibration of a multi-satellite sensitive installation matrix of a low-orbit small satellite according to claim 2, characterized in that: The attitude matrix R of the first star sensor in the inertial system S1 for: R S1 [0][0]=q 10 ×q 10 +q 11 ×q 11 -q 12 ×q 12 -q 13 ×q 13 R S1 [0][1]=2×(q 11 ×q 12 -q 10 ×q 13 ) R S1 [0][2]=2×(q 11 ×q 13 +q 10 ×q 12 ) R S1 [1][0]=2×(q 12 ×q 11 +q 10 ×q 13 ) R S1 [1][1]=q 10 ×q 10 -q 11 ×q 11 +q 12 ×q 12 -q 13 ×q 13 R S1 [1][2]=2×(q 12 ×q 13 -q 10 ×q 11 ) R S1 [2][0]=2×(q 11 ×q 13 -q 10 ×q 12 ) R S1 [2][1]=2×(q 12 ×q 13 +q 10 ×q 11 ) R S1 [2][2]=q 10 ×q 10 -q 11 ×q 11 -q 12 ×q 12 +q 13 ×q 13 In the formula, [q 10 q 11 q 12 q 13 ] is the quaternion of the first star sensitivity at a certain calibration time.

4. The method for rapid calibration of a multi-satellite sensitive installation matrix of a low-orbit small satellite according to claim 2, characterized in that: The attitude matrix R of the second star sensor in the inertial system S2 for: R S2 [0][0]=q 20 ×q 20 +q 21 ×q 21 -q 22 ×q 22 -q 23 ×q 23 R S2 [0][1]=2×(q 21 ×q 22 -q 20 ×q 23 ) R S2 [0][2]=2×(q 21 ×q 23 +q 20 ×q 22 ) R S2 [1][0]=2×(q 22 ×q 21 +q 20 ×q 23 ) R S2 [1][1]=q 20 ×q 20 -q 21 ×q 21 +q 22 ×q 22 -q 23 ×q 23 R S2 [1][2]=2×(q 22 ×q 23 -q 20 ×q 21 ) R S2 [2][0]=2×(q 21 ×q 23 -q 20 ×q 22 ) R S2 [2][1]=2×(q 22 ×q 23 +q 20 ×q 21 ) R S2 [2][2]=q 20 ×q 20 -q 21 ×q 21 -q 22 ×q 22 +q 23 ×q 23 In the formula, [q 20 q 21 q 22 q 23 ] is the quaternion of the second star sensitivity at a certain calibration time.

5. The method for rapid calibration of multi-satellite sensitive installation matrix of low-orbit small satellites according to claim 1 is characterized in that: In step S2, the second star sensor installation matrix after adjustment is: in: is the final calibration result of the second star sensor installation matrix after adjustment; j is the time point sequence number; R BS2j is the installation matrix result of the second star sensitivity at the jth time point; N is the total number of calibration points.

6. The method for rapid calibration of a multi-satellite sensitive installation matrix of a low-orbit small satellite according to claim 1, characterized in that: In step S3, the mth star sensor installation matrix after adjustment is obtained as: in: is the final calibration result of the mth star sensor installation matrix after adjustment; j is the time point sequence number; R BSmj is the installation matrix result of the mth star sensitivity at the jth time point; M is the total number of calibration points.

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