A method for online detection of misalignment angle of platform built-in star sensor

Abstract

The invention discloses an online detection method for the misalignment angle of a platform-built-in star sensor. First, an online detection device for the misalignment angle of a platform-built-in star sensor is built. Then, a conversion matrix between a hexahedron coordinate system and a theodolite coordinate system is calculated; a conversion matrix between the theodolite coordinate system and a star sensor target surface measurement coordinate system is calculated; a conversion matrix between the hexahedron coordinate system and a star sensor target surface measurement coordinate system is determined; and the star sensor misalignment angle is determined according to the conversion matrix between the hexahedron coordinate system and the star sensor target surface measurement coordinate system. The method of the invention does not need to disassemble the star sensor installed on the platform body, effectively shortens the time for retesting the long-term stability of the misalignment angle of the star sensor, improves the detection efficiency, and is a practical method for measuring the misalignment angle of a built-in star sensor.

Description

Technical Field

[0001] The invention relates to an online detection method for misalignment angle of a platform built-in star sensor, belonging to the technical field of inertial measurement. Background Art

[0002] The misalignment angle stability of the small hexahedron coordinate system installed on the star sensor and the star sensor target surface measurement coordinate system needs to complete at least three error calibrations before being put on the platform. The final measurement result can cover the accuracy drift caused by stress deformation. Based on the first and last calibration time requirements, the delivery time of the star sensor will be extended. When faced with more urgent delivery tasks, the static period will cause a great degree of delay. According to existing testing technology, the star sensor installed on the platform must be disassembled from the platform before the misalignment angle stability can be retested. If the platform parts are repeatedly disassembled and assembled for testing, the installation position will change each time, and the benchmark test data will change. Repeated disassembly will also affect the installation stability of the star sensor hexahedron. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to provide an online detection method for the misalignment angle of a platform-built-in star sensor, to achieve the measurement of the misalignment angle between the target surface measurement coordinate system of the star sensor installed in the platform and its optical reference hexahedron coordinate system without disassembly, and to improve the test efficiency and test accuracy.

[0004] The technical solution of the present invention is:

[0005] A method for online detection of misalignment angle of a platform built-in star sensor, comprising:

[0006] A platform-built star sensor misalignment angle online detection device is constructed, the online detection device comprising a star sensor, a reference prism, a multi-star simulator, a theodolite, a starlight platform and a computer; the star sensor is installed in the body of the starlight platform, the starlight platform and the star sensor orientation are adjusted so that the star sensor optical lens can measure the star target in the multi-star simulator, and after the star sensor orientation is determined, the frames of the starlight platform are locked to ensure that the position of the star sensor remains unchanged; at the same time, the theodolite can find two measurement positions, the front of the hexahedron and the reference prism can be measured at measurement position 1, and the side and the reference prism can be measured at measurement position 2;

[0007] Calculate the transformation matrix between the hexahedral coordinate system and the theodolite coordinate system;

[0008] Calculate the transformation matrix between the theodolite coordinate system and the star sensor target surface measurement coordinate system;

[0009] Determine the transformation matrix between the hexahedral coordinate system and the star sensor target surface measurement coordinate system;

[0010] The star sensor misalignment angle is determined according to the conversion matrix between the hexahedral coordinate system and the star sensor target surface measurement coordinate system, wherein the star sensor misalignment angle refers to the angle between the x-axis of the hexahedral coordinate system and the x-axis of the star sensor target surface measurement coordinate system, the angle between the y-axis of the hexahedral coordinate system and the y-axis of the star sensor target surface measurement coordinate system, and the angle between the z-axis of the hexahedral coordinate system and the z-axis of the star sensor target surface measurement coordinate system.

[0011] Preferably, the star sensor target surface measurement coordinate system is set to s X s Y s Z s Indicated by O b X b Y b Z b Indicated by O, the theodolite coordinate system j X j Y j Z j express;

[0012] The star sensor hexahedron has two mutually perpendicular mirrors, whose normal directions are used to indicate the x-axis and y-axis directions of the hexahedron coordinate system. The z-axis direction of the hexahedron coordinate system is determined by the right-hand rule.

[0013] The X-axis of the theodolite coordinate system is along the normal direction of the reference prism, the Y-axis is perpendicular to the local horizontal plane, and the Z-axis direction is determined by the right-hand rule.

[0014] Preferably, the method for calculating the conversion matrix between the hexahedral coordinate system and the theodolite coordinate system is as follows:

[0015] Place the theodolite at measurement position 1, measure the azimuth and elevation angles of the normal line of the front face of the star sensor hexahedron, record the azimuth and elevation angles of the reference prism at this time, and calculate the azimuth angle of the normal line of the front face of the hexahedron in the theodolite coordinate system. Pitch Angle Then the vector of the normal line of the hexahedron in the theodolite coordinate system is

[0016] Place the theodolite at measurement position 2, measure the azimuth and elevation angles of the normal line of the side surface of the star sensor hexahedron, and record the azimuth and elevation angles of the reference prism at this time, and calculate the azimuth angle of the normal line of the side surface of the hexahedron in the theodolite coordinate system. Pitch Angle Then the vector of the normal line of the hexahedron side surface in the theodolite coordinate system is

[0017] The z-axis positive vector V in the hexahedral coordinate system is obtained by the vector cross multiplication method. z =V x ×V y', positive y-axis vector V y =V z ×V x ;

[0018] Using the formula Calculate the transformation matrix between the hexahedral coordinate system and the theodolite coordinate system

[0019] Preferably, the method for calculating the conversion matrix between the theodolite coordinate system and the star sensor target surface measurement coordinate system is as follows:

[0020] (1) Place the theodolite at measurement position 1 and align it with the multi-star simulator, measure the azimuth and elevation angles of each star target in the multi-star simulator in the theodolite coordinate system, and record the azimuth and elevation angles of the reference prism when measuring each star target;

[0021] (2) Calculate the vector of each star target in the theodolite coordinate system according to the azimuth and elevation angles of the star target in the theodolite coordinate system;

[0022] (3) Powering on the star sensor, measuring each star target in the multi-star simulator, and recording the azimuth and elevation angles of each star target output by the star sensor in the star sensor target surface measurement coordinate system;

[0023] (4) calculating the vector of the star target in the star sensor target surface measurement coordinate system according to the azimuth and elevation angles of the star target in the star sensor target surface measurement coordinate system;

[0024] (5) Based on the vectors of the star target in the theodolite coordinate system and the star sensor target surface measurement coordinate system, calculate the transformation matrix between the theodolite coordinate system and the star sensor target surface measurement coordinate system.

[0025] Preferably, in step (2), if the azimuth of the i-th star target in the theodolite coordinate system is , the pitch angle is Then the vector of the i-th star target in the theodolite coordinate system is

[0026] Preferably, in step (4), if the azimuth of the i-th star target in the star sensor target surface measurement coordinate system is The pitch angle is Then the vector of the i-th star target in the star sensor target measurement coordinate system is Let x i =1.0, Then we have:

[0027]

[0028] Preferably, in step (5), the conversion matrix between the theodolite coordinate system and the star sensor target surface measurement coordinate system is

[0029]

[0030]

[0031] Preferably, the conversion matrix between the hexahedral coordinate system and the star sensor target surface measurement coordinate system is in is the transformation matrix between the hexahedral coordinate system and theodolite coordinate system, It is the transformation matrix between the theodolite coordinate system and the star sensor target measurement coordinate system.

[0032] Preferably,

[0033]

[0034] θ, φ is the angle between the y-axis of the hexahedral coordinate system and the y-axis of the star sensor target surface measurement coordinate system, the angle between the x-axis of the hexahedral coordinate system and the x-axis of the star sensor target surface measurement coordinate system, and the angle between the z-axis of the hexahedral coordinate system and the z-axis of the star sensor target surface measurement coordinate system.

[0035] Preferably, the theodolite is a self-collimating theodolite.

[0036] The beneficial effects of the present invention compared with the prior art are:

[0037] (1) The measurement method adopted by the present invention can re-measure the misalignment angle error of the star sensor when the star sensor has been assembled on the platform without disassembling the star sensor, thereby reducing the error caused by the assembly process and effectively improving the test accuracy. At the same time, the non-disassembly test method also effectively ensures the installation stability of the star sensor hexahedron.

[0038] (2) The present invention utilizes the platform body's own indexing mechanism to achieve optical axis alignment of the star sensor, effectively shortening the time for retesting the long-term stability of the star sensor misalignment angle.

[0039] (3) The present invention reduces the workload to a great extent. The most important thing is that it saves the time cost of assembly and reasonably uses the interval between the first and last tests, ensuring that the subsequent testing progress of the platform proceeds smoothly and improving the testing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Define diagrams for star sensors and hexahedral coordinate systems;

[0041] Figure 2 It is a schematic diagram of an online detection device;

[0042] Figure 3 This is a schematic diagram of the Starlight platform system structure. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0044] An online detection method for the misalignment angle of a star sensor is suitable for measuring the misalignment angle between the target surface measurement coordinate system of a star sensor installed on a platform and its optical reference hexahedron coordinate system. The misalignment angle of the star sensor is measured without disassembling the star sensor. The measurement result can be compared with the first measurement before the platform is installed to re-measure the stability of the misalignment angle.

[0045] like Figure 1 As shown, the star sensor hexahedron has two mutually perpendicular mirror surfaces, and their normal directions are used to indicate the x-axis direction and the y-axis direction of the star sensor hexahedron coordinate system respectively. The z-axis direction of the star sensor hexahedron coordinate system is determined by the right-hand rule, and the normals of the three mutually perpendicular faces of the hexahedron constitute the coordinate axes of the hexahedron coordinate system.

[0046] like Figure 2 As shown, a platform-based built-in star sensor misalignment angle online detection device is constructed. The X-axis of the theodolite coordinate system is along the normal direction of the reference prism, the Y-axis is perpendicular to the local horizontal plane, and the Z-axis direction is determined according to the right-hand rule.

[0047] The specific test steps are as follows:

[0048] The star sensor coordinate system is O s X s Y s Z s Indicated by O b X b Y b Z b Indicated by O, the theodolite coordinate system j X j Y j Z j express.

[0049] Adjust the orientation of the platform and star sensor so that the optical lens of the star sensor can measure the star targets in the multi-star simulator, and expose the star sensor hexahedron so that the theodolite can find two specific positions. At specific position 1, the front of the hexahedron and the reference prism can be measured simultaneously, and at specific position 2, the side and the reference prism can be measured simultaneously. After determining the orientation of the platform star sensor, lock the frames of the platform to ensure that the position of the star sensor remains unchanged.

[0050] 2) Measure the transformation matrix between the hexahedron coordinate system and the theodolite coordinate system

[0051] Place the theodolite at measurement position 1, measure the azimuth and elevation of the normal line of the front face of the star sensor hexahedron, and record the azimuth and elevation of the reference prism when measuring the front face of the hexahedron, and calculate the azimuth of the normal line of the front face of the hexahedron in the theodolite coordinate system. Pitch Then the vector of the normal line of the hexahedron in the theodolite coordinate system is Place the theodolite at measurement position 2, measure the azimuth and elevation of the normal line of the side surface of the star sensor hexahedron, and record the azimuth and elevation of the reference edge when measuring the normal line of the side surface of the hexahedron, and calculate the azimuth of the normal line of the side surface of the hexahedron in the theodolite coordinate system. Pitch , then the vector of the normal line of the hexahedron side surface in the longitude and latitude coordinate system is The z-axis positive vector V of the hexahedral coordinate system is established by the vector cross multiplication method z =V x ×V y ', positive y-axis vector V y =V z ×V x . Then the transformation matrix between the hexahedral coordinate system and the theodolite coordinate system can be calculated

[0052] 3) Measure the transformation matrix between the star sensor coordinate system and the hexahedron coordinate system

[0053] (1) Place the theodolite at measurement position 1 and aim it at the star simulator. Measure the azimuth and pitch of each star target in the star simulator respectively, and record the azimuth and pitch of the reference prism when measuring the star target. Calculate the azimuth of the i-th star target in the theodolite coordinate system. Pitch Then the vector of the star target in the theodolite coordinate system is

[0054] (2) Power on the star sensor, measure the star targets in the multi-star simulator, record the azimuth and pitch of each star target output by the star sensor, and calculate the vector of the star target in the star sensor target surface measurement coordinate system. Based on the vector of the star target in the theodolite coordinate system and the star sensor target surface measurement coordinate system, calculate the conversion matrix between the theodolite coordinate system and the star sensor target surface measurement coordinate system, and establish the relationship between the theodolite coordinate system and the star sensor target surface measurement coordinate system.

[0055] The position of the i-th star target in the star sensor coordinate system is Pitch Then the vector of the star target in the star sensor coordinate system is Let x i =1.0, Then we have:

[0056]

[0057] make:

[0058]

[0059] Then we have:

[0060]

[0061]

[0062] (3) According to the transformation matrix between the hexahedron coordinate system and theodolite coordinate system, and between theodolite coordinate system and the star sensor target surface measurement coordinate system, the transformation matrix between the hexahedron coordinate system and the star sensor target surface measurement coordinate system is calculated as follows: Thus, the misalignment angle between the star sensor and the hexahedron is obtained. Multiple measurement results are counted and compared with the first measurement before the platform is installed to re-measure the stability of the misalignment angle.

[0063]

[0064] θ, φ is the angle between the y-axis of the hexahedral coordinate system and the y-axis of the star sensor target surface measurement coordinate system, the angle between the x-axis of the hexahedral coordinate system and the x-axis of the star sensor target surface measurement coordinate system, and the angle between the z-axis of the hexahedral coordinate system and the z-axis of the star sensor target surface measurement coordinate system.

[0065] like Figure 3 As shown, in the above detection method, the starlight platform inertial navigation system adopts a two-frame three-axis structure, including a gyroscope, an accelerometer, a star sensor, an outer ring frame, an inner ring frame, a platform body, a torque motor, a photoelectric encoder, etc. The gyroscope, accelerometer and star sensor are installed on the platform body, and the outer ring frame, the inner ring frame and the platform body can rotate around the outer ring axis, the inner ring axis and the platform body axis respectively, respectively realizing single-degree-of-freedom rotation in the three directions of pitch, roll and yaw, and the torque motor and photoelectric encoder are installed at the shaft end of each frame. The starlight platform inertial navigation system provides a stable inertial space position for the test, and can be turned to realize the function of a turntable.

[0066] The method for realizing the platform body rotation of the Starlight Platform is as follows: the command angular velocity is a given value, and the stabilization loop control framework makes the platform body rotate at the given angular velocity. After the platform receives the rotation command, it performs attitude calculation according to the target attitude angle through the gyroscope output, performs rotation control by using the calculated difference, and then applies the command angular velocity to the stabilization loop to control the body rotation, so that the platform body quickly approaches the target position.

[0067] In view of the problem that the current misalignment angle test method is not suitable for star sensors that have been installed inside the frame-type inertial platform, the present invention proposes a method of measuring the misalignment angle of the star sensor online using the starlight inertial platform system, relying on the frame lock function of the starlight inertial platform system to provide a stable inertial space position for the star sensor, and read the star measurement data from the star sensor serial port. This method does not require the disassembly of the star sensor that has been installed on the platform body, and uses the platform body's own transfer mechanism to achieve the alignment of the star sensor optical axis, effectively shortening the time for retesting the long-term stability of the star sensor misalignment angle, and improving the detection efficiency. It is a practical and feasible built-in star sensor misalignment angle measurement method.

[0068] The present invention is applicable to a star sensor that has been installed on a platform body, and realizes re-measurement of the misalignment angle of the star sensor target surface without disassembling the star sensor, and compares the result with the first measurement before the platform is installed, so as to judge whether the stability of the first and last misalignment angles of the star sensor exceeds the tolerance, thereby improving the test efficiency and the test accuracy.

[0069] The present invention can effectively re-measure the long-term stability of the misalignment angle of the star sensor, thereby enhancing the comprehensiveness and accuracy of the test.

[0070] Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

Claims

1. A method for online detection of misalignment angle of a platform built-in star sensor, characterized in that include: A platform-built star sensor misalignment angle online detection device is constructed, the online detection device comprising a star sensor, a reference prism, a multi-star simulator, a theodolite, a starlight platform and a computer; the star sensor is installed in the body of the starlight platform, the starlight platform and the star sensor are positioned so that the optical lens of the star sensor can measure the star target in the multi-star simulator, and after the star sensor position is determined, the frames of the starlight platform are locked to ensure that the position of the star sensor remains unchanged; At the same time, the theodolite can find two measurement positions. At measurement position 1, the front of the hexahedron and the reference prism can be measured, and at measurement position 2, the side and the reference prism can be measured. Calculate the transformation matrix between the hexahedral coordinate system and the theodolite coordinate system; Calculate the transformation matrix between the theodolite coordinate system and the star sensor target surface measurement coordinate system; Determine the transformation matrix between the hexahedral coordinate system and the star sensor target surface measurement coordinate system; The star sensor misalignment angle is determined according to the conversion matrix between the hexahedral coordinate system and the star sensor target surface measurement coordinate system, wherein the star sensor misalignment angle refers to the angle between the x-axis of the hexahedral coordinate system and the x-axis of the star sensor target surface measurement coordinate system, the angle between the y-axis of the hexahedral coordinate system and the y-axis of the star sensor target surface measurement coordinate system, and the angle between the z-axis of the hexahedral coordinate system and the z-axis of the star sensor target surface measurement coordinate system.

2. The method for online detection of misalignment angle of a platform-built-in star sensor according to claim 1, characterized in that: The star sensor target surface measurement coordinate system is O s X s Y s Z s Indicated by O b X b Y b Z b Indicated by O, the theodolite coordinate system j X j Y j Z j express; The star sensor hexahedron has two mutually perpendicular mirrors, whose normal directions are used to indicate the x-axis and y-axis directions of the hexahedron coordinate system. The z-axis direction of the hexahedron coordinate system is determined by the right-hand rule. The X-axis of the theodolite coordinate system is along the normal direction of the reference prism, the Y-axis is perpendicular to the local horizontal plane, and the Z-axis direction is determined by the right-hand rule.

3. The method for online detection of misalignment angle of a platform built-in star sensor according to claim 1, characterized in that: The method for calculating the transformation matrix between the hexahedral coordinate system and the theodolite coordinate system is as follows: Place the theodolite at measurement position 1, measure the azimuth and elevation angles of the normal line of the front face of the star sensor hexahedron, record the azimuth and elevation angles of the reference prism at this time, and calculate the azimuth angle of the normal line of the front face of the hexahedron in the theodolite coordinate system. Pitch Angle Then the vector of the normal line of the hexahedron in the theodolite coordinate system is Place the theodolite at measurement position 2, measure the azimuth and elevation angles of the normal line of the side surface of the star sensor hexahedron, and record the azimuth and elevation angles of the reference prism at this time, and calculate the azimuth angle of the normal line of the side surface of the hexahedron in the theodolite coordinate system. Pitch Angle Then the vector of the normal line of the hexahedron side surface in the theodolite coordinate system is The z-axis positive vector V in the hexahedral coordinate system is obtained by the vector cross multiplication method. z =V x ×V y ', positive y-axis vector V y =V z ×V x ; Using the formula Calculate the transformation matrix between the hexahedral coordinate system and the theodolite coordinate system 4. The method for online detection of misalignment angle of a platform-built-in star sensor according to claim 1, characterized in that: The method for calculating the transformation matrix between the theodolite coordinate system and the star sensor target surface measurement coordinate system is as follows: (1) Place the theodolite at measurement position 1 and align it with the multi-star simulator, measure the azimuth and elevation angles of each star target in the multi-star simulator in the theodolite coordinate system, and record the azimuth and elevation angles of the reference prism when measuring each star target; (2) Calculate the vector of each star target in the theodolite coordinate system according to the azimuth and elevation angles of the star target in the theodolite coordinate system; (3) Powering on the star sensor, measuring each star target in the multi-star simulator, and recording the azimuth and elevation angles of each star target output by the star sensor in the star sensor target surface measurement coordinate system; (4) calculating the vector of the star target in the star sensor target surface measurement coordinate system according to the azimuth and elevation angles of the star target in the star sensor target surface measurement coordinate system; (5) Based on the vectors of the star target in the theodolite coordinate system and the star sensor target surface measurement coordinate system, calculate the transformation matrix between the theodolite coordinate system and the star sensor target surface measurement coordinate system.

5. The method for online detection of misalignment angle of a platform-built-in star sensor according to claim 4, characterized in that: In step (2), if the azimuth of the i-th star target in the theodolite coordinate system is The pitch angle is Then the vector of the i-th star target in the theodolite coordinate system is 6. The method for online detection of misalignment angle of a platform-built-in star sensor according to claim 5, characterized in that: In step (4), if the azimuth of the i-th star target in the star sensor target surface measurement coordinate system is The pitch angle is Then the vector of the i-th star target in the star sensor target measurement coordinate system is Let x i =1.0, Then we have:

7. The method for online detection of misalignment angle of a platform-built-in star sensor according to claim 6, characterized in that: In step (5), the conversion matrix between the theodolite coordinate system and the star sensor target surface measurement coordinate system is 8. The method for online detection of misalignment angle of a platform-built-in star sensor according to claim 1, characterized in that: The transformation matrix between the hexahedral coordinate system and the star sensor target surface measurement coordinate system is: in is the transformation matrix between the hexahedral coordinate system and theodolite coordinate system, It is the transformation matrix between the theodolite coordinate system and the star sensor target measurement coordinate system.

9. The method for online detection of misalignment angle of a platform-built-in star sensor according to claim 8, characterized in that: θ, φ is the angle between the y-axis of the hexahedral coordinate system and the y-axis of the star sensor target surface measurement coordinate system, the angle between the x-axis of the hexahedral coordinate system and the x-axis of the star sensor target surface measurement coordinate system, and the angle between the z-axis of the hexahedral coordinate system and the z-axis of the star sensor target surface measurement coordinate system.

10. The method for online detection of misalignment angle of a platform-built-in star sensor according to claim 1, characterized in that: The theodolite is a self-collimating theodolite.

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