A control method of a dual-axis rotating mechanism of a moving base inertial celestial integrated navigation system

Abstract

This invention relates to a control method for a dual-axis rotation mechanism in a moving-base inertial astronomical navigation system, comprising: S1: establishing a coordinate system and modeling the installation angle of the dual-axis rotation mechanism structure; S2: determining the target attitude information of the target star to be observed by the astronomical navigation system in the geographic coordinate system based on the established coordinate system; S3: acquiring the attitude information of the moving base in the geographic coordinate system; S4: after acquiring the target attitude information and the moving base attitude information, acquiring the current actual rotation state of the rotation mechanism, and reading the angle information of the two rotating frames at the current moment through the angle encoders of the outer and inner frames, and constructing the corresponding relative information; S5: based on the known target attitude information, moving base attitude information, and relative information, establishing a control model of the dual-axis rotation mechanism using attitude calculation and matrix operation methods. This invention achieves precise control of the external orientation dual-axis rotation mechanism of an inertial astronomical navigation system under moving-base conditions.

Description

Technical Field

[0001] This invention relates to the field of inertial astronomical integrated navigation, and more particularly to a control method for a dual-axis rotation mechanism in a moving-base inertial astronomical integrated navigation system. Background Technology

[0002] An inertial-astronomical integrated navigation system based on a small field-of-view star tracker is a high-precision navigation device. Its core components include an inertial navigation system (INS), a celestial navigation system (CNS), and an external orientation dual-axis rotation mechanism. The INS and celestial navigation system are coaxially fixed to the external orientation dual-axis rotation mechanism, achieving coordinated rotation within a unified framework. Due to its high precision and high update rate, this system has been widely used in various platforms such as ships, vehicles, and aircraft.

[0003] Astronomical navigation systems based on small field-of-view star trackers have advantages such as high signal-to-noise ratio, high reliability, and all-weather operation. By observing specific stars and processing them through image acquisition, star map query, and star point matching, the system obtains accurate astronomical navigation information, thereby providing necessary external measurement information for inertial astronomical integrated navigation systems.

[0004] However, due to the narrow field of view (only angular increments) of small field-of-view star trackers, only one star can typically be observed within a single field of view. This characteristic places high demands on the control strategy of the external orientation dual-axis rotation mechanism in astronomical navigation systems. If there is a deviation in the control angle, the target star will not fall within the star tracker's field of view. In dynamic application scenarios such as vehicle-mounted or airborne systems, the high mobility of the platform places even higher demands on the control accuracy of the external orientation dual-axis rotation mechanism. Therefore, achieving precise control of the external orientation dual-axis rotation mechanism under moving base conditions is not only of great significance for ensuring the stable operation of astronomical navigation systems using small field-of-view star trackers and improving the performance of inertial astronomical integrated navigation systems, but also a key problem that urgently needs to be solved. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a control method for a dual-axis rotation mechanism in a moving-base inertial astronomical integrated navigation system, thereby achieving precise control of the external orientation dual-axis rotation mechanism under moving-base conditions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A control method for a dual-axis rotation mechanism in a moving-base inertial astronomy integrated navigation system includes the following steps: S1: Define all types of coordinate systems involved in the system in a unified manner, establish a coordinate system, and model the installation angle of the dual-axis indexing mechanism structure; S2: Based on the established coordinate system, determine the target attitude information of the target star that the astronomical navigation system needs to observe in the geographic coordinate system; S3: Obtain the dynamic base attitude information in the geographic coordinate system; S4: After obtaining the target attitude information and the dynamic base attitude information, obtain the current actual rotation state of the indexing mechanism. Through the angle encoders of the outer frame and the inner frame, read the angle information of the two-stage rotating frames at the current moment and construct the corresponding relative information. S5: Based on the known target attitude information, moving base attitude information, and relative information, a control model for the dual-axis indexing mechanism is established using attitude calculation and matrix operation methods.

[0007] Furthermore, a unified definition is established for various coordinate systems involved in the system, including the IMU volume coordinate system, the astronomical navigation system volume coordinate system, the navigation coordinate system, and the outer frame zero coordinate system, outer frame encoder coordinate system, inner frame zero coordinate system, and inner frame encoder coordinate system of the dual-axis rotation mechanism.

[0008] Furthermore, the installation angle modeling of the dual-axis indexing mechanism is performed, including the installation angle modeling between the outer frame and the inner frame, and the installation angle modeling between the inner frame and the IMU, as detailed below: The installation structure angle modeling between the outer frame and the inner frame is as follows: Coordinate system of the outer frame encoder disk of the indexing mechanism. With the zero coordinate system of the inner frame There will be small angular installation errors in the pitch and roll axes, which will be modeled as follows: ; in, Represents the coordinate system of the outer frame encoder disk With the zero coordinate system of the inner frame The installation error matrix between them express The transpose of the matrix, Represents a third-order identity matrix. Representing the relevant matrix The transpose of the matrix, Representing the relevant matrix Antisymmetric matrix operations, , and Characterizing the outer frame code disk coordinate system With the zero coordinate system of the inner frame The pitch and roll installation angles between the two structures; Modeling of the mounting structure angles between the inner frame and the IMU, and the coordinate system of the inner frame encoder disk of the indexing mechanism. With IMU coordinate system There will be small angular installation errors in the roll axis and azimuth axis, which will be modeled as follows: ; in, Indicates the coordinate system of the inner frame code disk With IMU coordinate system The installation error matrix between them express The transpose of the matrix, , and Characterizing the coordinate system of the code disk within the transposition mechanism With IMU coordinate system The roll mounting structure angle and azimuth mounting structure angle between them.

[0009] Furthermore, based on the established coordinate system, the target attitude information of the target star that the astronomical navigation system needs to observe in the geographic coordinate system is determined, as follows: The target attitude refers to the three-axis attitude information of the target star to be observed by the astronomical navigation system in the geographic frame, specifically modeled as follows: ; in, Let represent the attitude rotation matrix of the astronomical navigation system from the volume coordinate system s to the navigation coordinate system n at time t. , and These represent the pitch angle, roll angle, and azimuth angle of the astronomical navigation system, respectively. Due to installation discrepancies between the inertial navigation system and the celestial navigation system, there will be a small three-axis angular installation deviation between the IMU coordinate system b and the celestial navigation system volume coordinate system s. According to the matrix chain multiplication relationship, the three-axis attitudes of the inertial navigation system and the celestial navigation system satisfy the following relationship: ; in, Let represent the attitude rotation matrix from IMU coordinate system b to navigation coordinate system n at time t. ; ; in, , , , These represent the pitch, roll, and azimuth installation angles between the inertial navigation system and the celestial navigation system, respectively. , and These represent the pitch angle, roll angle, and azimuth angle of the inertial navigation system, respectively. Through the coordinate system transformation described above, the target attitude of the astronomical navigation system is... , and Convert the target attitude into an inertial navigation system , and .

[0010] Furthermore, the attitude information of the moving base in the geographic coordinate system is obtained, as follows: The base attitude is the three-axis attitude information of the carrier in the navigation coordinate system, and is modeled as follows: ; in, This represents the zero-position coordinate system of the outer frame of the indexing mechanism at time t. The attitude rotation matrix to the navigation coordinate system n. , and These represent the vehicle's pitch angle, roll angle, and azimuth angle, respectively.

[0011] Furthermore, the angle information of the two-level rotating frame at the current moment is read, and the corresponding relative information is constructed, as follows: By taking the attitude information of the outer frame angle encoder at time t, and measuring the angle encoder information by rotating the outer frame, we can obtain... System relative to Relative attitude array of the system , is represented as: ; in, This indicates the angle measured by the outer frame angle encoder. By reading the frame angle encoder attitude information at time t, and measuring the frame angle encoder information by rotating the inner frame, the following can be obtained: System relative to Relative attitude array of the system , is represented as: ; in, This indicates the angle measured by the inner frame angle encoder.

[0012] Furthermore, using attitude calculation and matrix operation methods, a control model for the dual-axis rotation mechanism is established, including the calculation of the target control angle of the outer frame, the calculation of the target control angle of the inner frame, and the simplified calculation of the target control angles of the outer and inner frames.

[0013] Furthermore, the calculation of the outer frame target control angle is as follows: Based on attitude demodulation technology, the base attitude array Represented as: ; Let the time interval be The angle control amount of the inner and outer frame rotation is: The angle control amount of the inner frame rotation frame is Then the base attitude array As shown: ; in: ; in, , , and They represent The increment of the sensitive angle of the three-axis gyroscope and the increment of the n-series rotation angle within a time period; because and Since the angle value is small, the rotation of the frame satisfies commutativity, that is: , ; in, and They are respectively The relative attitude matrix of the rotating frame between the inner and outer frames at any given time; Therefore, the base attitude array Represented as: ; Rearranging the above equation, we get: ; Define matrix Then the above formula can be rewritten as: ; From the above formula, the target control angle of the outer frame rotation frame is: ; in, Representation matrix No. i Line number j Elements in a column.

[0014] Furthermore, the calculation of the inner frame target control angle is as follows: The relative attitude matrix of the inner frame rotation during the time interval is modeled as follows: ; Therefore, the target control angle of the inner frame rotation frame is: .

[0015] Furthermore, the simplified calculation of the target control angles for the outer and inner frames is as follows: Because the control of the dual-axis indexing mechanism is a high-frequency continuous control process, the angle control amount of the outer frame rotation frame in a short time is limited. Angle control amount of the inner frame rotating frame Since all angles are small, second-order small-quantity errors are ignored. Simplified to: ; Therefore, the target control angles for the outer frame rotation frame and the inner frame rotation frame are as follows: .

[0016] The present invention has the following beneficial effects: This invention enables high-precision pointing control of the external orientation dual-axis rotation mechanism under dynamic conditions, thereby ensuring accurate observation of the target star by the small field-of-view star tracker. This not only helps maintain the stable operation of the astronomical navigation system, but also effectively improves the overall navigation performance of the entire inertial astronomical integrated navigation system. Attached Figure Description

[0017] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: refer to Figure 1 In this embodiment, a control method for a dual-axis rotation mechanism of a moving-base inertial astronomy integrated navigation system is provided, comprising the following steps: S1: Define all types of coordinate systems involved in the system in a unified manner, establish a coordinate system, and model the installation angle of the dual-axis indexing mechanism structure; S2: Based on the established coordinate system, determine the target attitude information of the target star that the astronomical navigation system needs to observe in the geographic coordinate system, and represent it as a target attitude rotation matrix containing pitch angle, roll angle and azimuth angle. S3: Obtain the attitude information of the moving base in the geographic coordinate system, including pitch angle, roll angle and azimuth angle, and construct the corresponding moving base attitude rotation matrix; S4: After obtaining the target attitude information and the dynamic base attitude information, obtain the current actual rotation state of the indexing mechanism. Through the angle encoders of the outer frame and the inner frame, read the angle information of the two-stage rotating frames at the current moment and construct the corresponding relative information. S5: Based on the known target attitude information, moving base attitude information, and relative information, a control model for the dual-axis indexing mechanism is established using attitude calculation and matrix operation methods.

[0019] In this embodiment, a unified coordinate system is established for all types of coordinate systems involved in the system, including the IMU volume coordinate system, the astronomical navigation system volume coordinate system, the navigation coordinate system, and the outer frame zero-position coordinate system, outer frame encoder disk coordinate system, inner frame zero-position coordinate system, and inner frame encoder disk coordinate system of the dual-axis rotation mechanism. The specific definitions are as follows: (1) IMU volume coordinate system (Coordinate system): Orthogonal right-handed coordinate system, origin Located in the sensitive center of IMU, , and The right-front-top coordinate system constitutes the IMU. In this method, this coordinate system can be regarded as the volume coordinate system of the inertial navigation system.

[0020] (2) The volume coordinate system of the astronomical navigation system ( (Coordinate system): Orthogonal right-handed coordinate system, origin Located at the center of the image plane, , and The right-front-up coordinate system constitutes the star tracker.

[0021] (3) Navigation coordinate system n (Coordinate system): Orthogonal right-handed coordinate system , and This forms the East-North-Sky geographical coordinate system.

[0022] (4) Zero coordinate system of outer frame of indexing mechanism ( (Coordinate system): Orthogonal right-handed coordinate system, origin Located at the rotation center of the outer frame of the indexing mechanism, Parallel to the rotation axis of the outer frame and The orientation of the coordinate system does not change with the rotation of the outer frame. This coordinate system can be regarded as the body coordinate system of the dual-axis indexing mechanism, and in this method, it can also be regarded as the carrier coordinate system.

[0023] (5) Coordinate system of the outer frame encoder of the indexing mechanism ( (Coordinate system): Orthogonal right-handed coordinate system, origin Located at the rotation center of the outer frame of the indexing mechanism, Parallel to the rotation axis of the outer frame and The orientation of the object changes as the outer frame rotates.

[0024] (6) Zero coordinate system of the inner frame of the indexing mechanism ( (Coordinate system): Orthogonal right-handed coordinate system, origin Located at the rotation center of the inner frame of the indexing mechanism, Parallel to the rotation axis of the inner frame and The orientation does not change with the rotation of the inner frame.

[0025] (7) Coordinate system of the inner frame encoder of the indexing mechanism ( (Coordinate system): Orthogonal right-handed coordinate system, origin Located at the rotation center of the inner frame of the indexing mechanism, Parallel to the rotation axis of the inner frame and The orientation changes as the inner frame rotates. In this embodiment, the mounting angle modeling of the dual-axis indexing mechanism structure is performed, including the mounting angle modeling between the outer frame and the inner frame and the mounting angle modeling between the inner frame and the IMU, as detailed below: The installation structure angle modeling between the outer frame and the inner frame is as follows: Due to the limited assembly accuracy of the indexing mechanism, the coordinate system of the outer frame encoder disk of the indexing mechanism... With the zero coordinate system of the inner frame There will be small angular installation errors in the pitch and roll axes, which will be modeled as follows: ; in, Represents the coordinate system of the outer frame encoder disk With the zero coordinate system of the inner frame The installation error matrix between them express The transpose of the matrix, Represents a third-order identity matrix. Representing the relevant matrix The transpose of the matrix, Representing the relevant matrix Antisymmetric matrix operations, , and Characterizing the outer frame code disk coordinate system With the zero coordinate system of the inner frame The pitch and roll installation angles between the two structures; Modeling the installation structure angle between the inner frame and the IMU, due to installation deviations of the inertial navigation system, the coordinate system of the inner frame encoder disk of the indexing mechanism. With IMU coordinate system There will be small angular installation errors in the roll axis and azimuth axis, which will be modeled as follows: in, Indicates the coordinate system of the inner frame code disk With IMU coordinate system The installation error matrix between them express The transpose of the matrix, , and Characterizing the coordinate system of the code disk within the transposition mechanism With IMU coordinate system The roll mounting structure angle and azimuth mounting structure angle between them.

[0026] In this embodiment, based on the established coordinate system, the target attitude information of the target star that the astronomical navigation system needs to observe in the geographic coordinate system is determined, as follows: The target attitude refers to the three-axis attitude information of the target star to be observed by the astronomical navigation system in the geographic frame, specifically modeled as follows: in, Let represent the attitude rotation matrix of the astronomical navigation system from the volume coordinate system s to the navigation coordinate system n at time t. , and These represent the pitch angle, roll angle, and azimuth angle of the astronomical navigation system, respectively. Due to installation discrepancies between the inertial navigation system and the celestial navigation system, there will be a small three-axis angular installation deviation between the IMU coordinate system b and the celestial navigation system volume coordinate system s. According to the matrix chain multiplication relationship, the three-axis attitudes of the inertial navigation system and the celestial navigation system satisfy the following relationship: in, Let represent the attitude rotation matrix from IMU coordinate system b to navigation coordinate system n at time t. ; in, , , , These represent the pitch, roll, and azimuth installation angles between the inertial navigation system and the celestial navigation system, respectively. , and These represent the pitch angle, roll angle, and azimuth angle of the inertial navigation system, respectively. Through the coordinate system transformation described above, the target attitude of the astronomical navigation system is... , and Convert the target attitude into an inertial navigation system , and .

[0027] In this embodiment, the attitude information of the moving base in the flight coordinate system is obtained as follows: The base attitude is the three-axis attitude information of the carrier in the geographic frame, and is modeled as follows: ;in, This represents the zero-position coordinate system of the outer frame of the indexing mechanism at time t. The attitude rotation matrix to the navigation coordinate system n. , and These represent the vehicle's pitch angle, roll angle, and azimuth angle, respectively.

[0028] In this embodiment, the angle information of the two-stage rotating frame at the current moment is read, and the corresponding relative information is constructed, as follows: By taking the attitude information of the outer frame angle encoder at time t, and measuring the angle encoder information by rotating the outer frame, we can obtain... System relative to Relative attitude array of the system , is represented as: ; in, This indicates the angle measured by the outer frame angle encoder. By reading the frame angle encoder attitude information at time t, and measuring the frame angle encoder information by rotating the inner frame, the following can be obtained: System relative to Relative attitude array of the system , is represented as: ; in, This indicates the angle measured by the inner frame angle encoder.

[0029] In this embodiment, a control model for a dual-axis rotation mechanism is established using attitude calculation and matrix operation methods, including calculation of the target control angle of the outer frame, calculation of the target control angle of the inner frame, and simplified calculation of the target control angles of the outer and inner frames.

[0030] In this embodiment, the target control angle of the outer frame is calculated as follows: Based on attitude demodulation technology, the base attitude array Represented as: ; Let the time interval be The angle control amount of the inner and outer frame rotation is: The angle control amount of the inner frame rotation frame is Then the base attitude array As shown: ; in: ; ; ; ; in, , , and They represent The increment of the sensitive angle of the three-axis gyroscope and the increment of the n-series rotation angle within a time period; because and Since the angle value is small, the rotation of the frame satisfies commutativity, that is: , in, and They are respectively The relative attitude matrix of the rotating frame between the inner and outer frames at any given time; Therefore, the base attitude array Represented as: ; Rearranging the above equation, we get: ; Define matrix Then the above formula can be rewritten as: ; From the above formula, the target control angle of the outer frame rotation frame is: ; in, Representation matrix No. i Line number j Elements in a column.

[0031] In this embodiment, the inner frame target control angle is calculated as follows: The relative attitude matrix of the inner frame rotation during the time interval is modeled as follows: ; Therefore, the target control angle of the inner frame rotation frame is: .

[0032] In this embodiment, the calculation of the target control angles of the outer and inner frames is simplified, as follows: Because the control of the dual-axis indexing mechanism is a high-frequency continuous control process, the angle control amount of the outer frame rotation frame in a short time is limited. Angle control amount of the inner frame rotating frame Since all angles are small, second-order small-quantity errors are ignored. Simplified to: ; Therefore, the target control angles for the outer frame rotation frame and the inner frame rotation frame are as follows: .

[0033] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0034] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0035] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0036] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for controlling a dual-axis rotation mechanism of a moving base inertial astronomical integrated navigation system, characterized in that, Includes the following steps: S1: Define all types of coordinate systems involved in the system in a unified manner, establish a coordinate system, and model the installation angle of the dual-axis indexing mechanism structure; S2: Based on the established coordinate system, determine the target attitude information of the target star that the astronomical navigation system needs to observe in the geographic coordinate system; S3: Obtain the dynamic base attitude information in the geographic coordinate system; S4: After obtaining the target attitude information and the dynamic base attitude information, obtain the current actual rotation state of the indexing mechanism. Through the angle encoders of the outer frame and the inner frame, read the angle information of the two-stage rotating frames at the current moment and construct the corresponding relative information. S5: Based on the known target attitude information, moving base attitude information, and relative information, a control model for the dual-axis indexing mechanism is established using attitude calculation and matrix operation methods.

2. The control method for a dual-axis rotation mechanism of a moving-base inertial astronomical integrated navigation system according to claim 1, characterized in that, The system defines a unified coordinate system for all types of coordinate systems involved in the system, including the IMU volume coordinate system, the astronomical navigation system volume coordinate system, the navigation coordinate system, and the outer frame zero coordinate system, outer frame encoder coordinate system, inner frame zero coordinate system, and inner frame encoder coordinate system of the dual-axis rotation mechanism.

3. The control method for a dual-axis rotation mechanism of a moving-base inertial astronomical integrated navigation system according to claim 1, characterized in that, The process of modeling the installation angles of the dual-axis indexing mechanism includes modeling the installation angles between the outer and inner frames and between the inner frame and the IMU, as detailed below: The installation structure angle modeling between the outer frame and the inner frame is as follows: Coordinate system of the outer frame encoder disk of the indexing mechanism. With the zero coordinate system of the inner frame There will be small angular installation errors in the pitch and roll axes, which will be modeled as follows: ； in, Represents the coordinate system of the outer frame encoder disk With the zero coordinate system of the inner frame The installation error matrix between them express The transpose of the matrix, Represents a third-order identity matrix. Representing the relevant matrix The transpose of the matrix, Representing the relevant matrix Antisymmetric matrix operations, , and Characterizing the outer frame code disk coordinate system With the zero coordinate system of the inner frame The pitch and roll installation angles between the two structures; Modeling of the mounting structure angles between the inner frame and the IMU, and the coordinate system of the inner frame encoder disk of the indexing mechanism. With IMU coordinate system There will be small angular installation errors in the roll axis and azimuth axis, which will be modeled as follows: ； in, Indicates the coordinate system of the inner frame code disk With IMU coordinate system The installation error matrix between them express The transpose of the matrix, , and Characterizing the coordinate system of the code disk within the transposition mechanism With IMU coordinate system The roll mounting structure angle and azimuth mounting structure angle between them.

4. The control method for a dual-axis rotation mechanism of a moving-base inertial astronomical integrated navigation system according to claim 1, characterized in that, Based on the established coordinate system, the target attitude information of the target star to be observed by the astronomical navigation system in the geographic coordinate system is determined as follows: The target attitude refers to the three-axis attitude information of the target star to be observed by the astronomical navigation system in the geographic frame, specifically modeled as follows: ； in, Let represent the attitude rotation matrix of the astronomical navigation system from the volume coordinate system s to the navigation coordinate system n at time t. , and These represent the pitch angle, roll angle, and azimuth angle of the astronomical navigation system, respectively. Due to installation discrepancies between the inertial navigation system and the celestial navigation system, there will be a small three-axis angular installation deviation between the IMU coordinate system b and the celestial navigation system volume coordinate system s. According to the matrix chain multiplication relationship, the three-axis attitudes of the inertial navigation system and the celestial navigation system satisfy the following relationship: ； in, Let represent the attitude rotation matrix from IMU coordinate system b to navigation coordinate system n at time t. ; ； in, , , , These represent the pitch, roll, and azimuth installation angles between the inertial navigation system and the celestial navigation system, respectively. , and These represent the pitch angle, roll angle, and azimuth angle of the inertial navigation system, respectively. Through the coordinate system transformation described above, the target attitude of the astronomical navigation system is... , and Convert the target attitude into an inertial navigation system , and .

5. The control method for a dual-axis rotation mechanism of a moving-base inertial astronomical integrated navigation system according to claim 1, characterized in that, The specific steps for obtaining the dynamic base attitude information in the geographic coordinate system are as follows: The base attitude is the three-axis attitude information of the carrier in the navigation coordinate system, and is modeled as follows: ； in, This represents the zero-position coordinate system of the outer frame of the indexing mechanism at time t. The attitude rotation matrix to the navigation coordinate system n. , and These represent the vehicle's pitch angle, roll angle, and azimuth angle, respectively.

6. The control method for a dual-axis rotation mechanism of a moving-base inertial astronomical integrated navigation system according to claim 1, characterized in that, The process of reading the angle information of the two-level rotating frame at the current moment and constructing the corresponding relative information is as follows: By taking the attitude information of the outer frame angle encoder at time t, and measuring the angle encoder information by rotating the outer frame, we can obtain... System relative to Relative attitude array of the system , is represented as: ； in, This indicates the angle measured by the outer frame angle encoder. By reading the frame angle encoder attitude information at time t, and measuring the frame angle encoder information by rotating the inner frame, the following can be obtained: System relative to Relative attitude array of the system , is represented as: ； in, This indicates the angle measured by the inner frame angle encoder.

7. The control method for a dual-axis rotation mechanism of a moving-base inertial astronomical integrated navigation system according to claim 1, characterized in that, The control model of the dual-axis rotation mechanism is established by using attitude calculation and matrix operation methods, including the calculation of the target control angle of the outer frame, the calculation of the target control angle of the inner frame, and the simplified calculation of the target control angle of the outer and inner frames.

8. The control method for a dual-axis indexing mechanism of a moving-base inertial astronomical integrated navigation system according to claim 7, characterized in that, The calculation of the target control angle of the outer frame is as follows: Based on attitude demodulation technology, the base attitude array Represented as: ； Let the time interval be The angle control amount of the inner and outer frame rotation is: The angle control amount of the inner frame rotation frame is Then the base attitude array As shown: ； in: ； ； ； ； in, , , and They represent The increment of the sensitive angle of the three-axis gyroscope and the increment of the n-series rotation angle within a time period; because and Since the angle value is small, the rotation of the frame satisfies commutativity, that is: ， ； in, and They are respectively The relative attitude matrix of the rotating frame between the inner and outer frames at any given time; Therefore, the base attitude array Represented as: ； Rearranging the above equation, we get: ； Define matrix Then the above formula can be rewritten as: ； From the above formula, the target control angle of the outer frame rotation frame is: ； in, Representation matrix No. i Line number j Elements in a column.

9. The control method for a dual-axis indexing mechanism of a moving-base inertial astronomical integrated navigation system according to claim 8, characterized in that, The calculation of the target control angle of the inner frame is as follows: The relative attitude matrix of the inner frame rotation during the time interval is modeled as follows: ； Therefore, the target control angle of the inner frame rotation frame is: 。 10. The control method for a dual-axis indexing mechanism of a moving-base inertial astronomical integrated navigation system according to claim 9, characterized in that, The simplified calculation of the target control angles for the outer and inner frames is as follows: Because the control of the dual-axis indexing mechanism is a high-frequency continuous control process, the angle control amount of the outer frame rotation frame in a short time is limited. Angle control amount of the inner frame rotating frame Since all angles are small, second-order small-quantity errors are ignored. Simplified to: ； Therefore, the target control angles for the outer frame rotation frame and the inner frame rotation frame are as follows: 。

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