A USB axis system parameter calibration method based on BeiDou system

Abstract

The present invention relates to a shipborne USB shaft system parameter calibration scheme based on the Beidou system. The scheme fully utilizes the advantages of Beidou satellite resources, such as abundant resources, uniform distribution, consistent frequency, and real-time acquisition of orbit information, as well as advantageous conditions such as the 360-degree steering capability of ships, thereby improving the efficiency and reliability of USB shaft system parameter calibration. Model establishment and calibration can be carried out in dynamic or static conditions, reducing the restrictions of external objective conditions on model establishment. Compared with low-orbit calibration satellites, the Beidou satellite orbit is higher, so a more precise theoretical angle reference can be obtained. In theory, the shipborne USB shaft system parameter calibration scheme based on the Beidou system can obtain more precise shaft system parameters. Satellite ephemeris and ship position information are used to obtain theoretical azimuth and pitch angles, and a USB angle measurement error correction model can be established without the need for auxiliary tracking equipment, thereby having high practical value.

Description

Technical Field

[0001] The present invention belongs to the field of aerospace measurement and control technology, and relates to a USB axis system parameter calibration method based on the Beidou system. Background Art

[0002] Currently, the USB system has successfully implemented a method for directly calibrating electrical axis parameters by tracking precise orbit targets. However, this method currently primarily uses calibration satellites as tracking targets (like other satellites, only one type of satellite can be used due to inconsistent frequencies). This method is limited by the small number of calibration satellites, long orbit return periods, and poor single-tracking angle coverage. Calibration requires multiple days of tracking, and the long period for obtaining post-precision orbits results in poor calibration timeliness and susceptibility to environmental changes. Currently, my country's BeiDou-3 satellite navigation system has officially launched services. BeiDou satellite resources are numerous, evenly distributed, and have the same frequency, including satellites with different orbital periods. This provides ample calibration targets for USB axis system parameter calibration.

[0003] In response to the shortcomings of current calibration methods, the present invention provides a ship-borne USB shaft system parameter calibration scheme based on the Beidou system. The scheme fully utilizes the characteristics of Beidou satellite resources, such as abundant resources, uniform distribution, consistent frequency, and real-time acquisition of orbital information, as well as the advantageous conditions such as the ship's 360° steering ability, thereby improving the efficiency and reliability of USB shaft system parameter calibration; model establishment and calibration can be carried out in dynamic or static conditions, reducing the limitations of external objective conditions for model establishment; compared with low-orbit calibration satellites, the Beidou satellite orbit is higher, so a higher-precision theoretical angle reference can be obtained. In theory, the ship-borne USB shaft system parameter calibration scheme based on the Beidou system can obtain higher-precision shaft system parameters; the theoretical azimuth and pitch angles are obtained by using satellite ephemeris and ship position information, and a USB angle measurement error correction model can be established without the need for auxiliary tracking of other equipment, thereby having high practical value. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a USB shaft system parameter calibration method based on the BeiDou system in response to the above-mentioned existing technology, which facilitates the USB system to carry out shaft system parameter calibration under dynamic conditions at sea and improves the efficiency and reliability of shaft system parameter calibration.

[0005] The technical solution adopted by the present invention to solve the above problem is: a USB axis system parameter calibration method based on the Beidou system, the method comprising the following steps:

[0006] Step 1: Obtain Beidou satellite ephemeris data;

[0007] Step 2: Carry out BeiDou satellite visibility forecast and determine whether the time period meets the optimal observation conditions for USB axis system parameter calibration;

[0008] Step 3: Develop a USB tracking BeiDou satellite plan;

[0009] Step 4: Generate USB system boot data using satellite ephemeris data and survey vessel position information according to the USB tracking BeiDou satellite solution;

[0010] Step 5: Guide the USB device to track BeiDou satellites according to the boot data;

[0011] Step 6: Based on the USB angle measurement error correction model and the relevant data recorded in step 5), the USB axis parameters are obtained;

[0012] Step 7: Track BeiDou satellites in other time periods to test and verify the accuracy of USB axis parameters.

[0013] Preferably, the optimal observation conditions for the USB axis parameter calibration in step 2 are determined as follows: when the ship can turn 360°, the judgment standard for the optimal observation conditions for the USB axis parameter calibration is that there are at least 3 Beidou satellites with an altitude angle within the range of 20° to 60° during the tracking time period, and they are evenly distributed; when the ship sails according to a fixed route, the judgment standard for the optimal observation conditions for the USB axis parameter calibration is that at least 40 to 50 Beidou satellites can be tracked within the range of 20° to 60° during the tracking time period, and the tracked Beidou satellites are evenly distributed in each quadrant.

[0014] Preferably, the USB angle measurement error correction model in step 6 is:

[0015] E=E c -β m ·cos(AA m )-C e -ΔE Z -ΔE g ·cosE (1)

[0016] A=A c -β m ·tanE·sin(AA m )-δ m tanE-S b ·secE-C S ·secE-ΔA Z ·secE (2)

[0017] Where, the pitch angle after axis error correction, E c The pitch angle after ground zero correction, A The azimuth angle after axis system error correction, A c Azimuth after ground zero correction, β m The maximum tilt of the disk is not horizontal, A mThe maximum tilt direction of the disk is not horizontal; C S Antenna photoelectric axis is not matched laterally, C e Antenna photoelectric axis longitudinal mismatch, ΔA Z Azimuth dynamic hysteresis, ΔE Z Pitch dynamic hysteresis, ΔE g Gravity sag, δ m The pitch axis and azimuth axis are not orthogonal, S b The pitch axis and the optical axis are not orthogonal, A c =A usb -A0,E c =E usb -E0,A usb and E usb are the measured values ​​of USB azimuth and elevation angles, A0 and E0 are the azimuth zero position and elevation zero position.

[0018] Preferably, the method of obtaining USB axis parameters according to the USB angle measurement error correction model in step 6 includes the following steps:

[0019] 1) Use the shipborne USB device to track BeiDou satellites and obtain USB observation data. Use the default or initial axis system parameters and use formulas (1) and (2) to obtain the USB measured azimuth and pitch angle data.

[0020] 2) Using the survey ship and BeiDou satellite position information, the position vector enu of the BeiDou satellite in the local rectangular coordinate system can be calculated:

[0021]

[0022] Among them, x, y, z are the positions of the satellite in the spatial rectangular coordinate system, x0, y0, z0 are the positions of the survey ship in the spatial rectangular coordinate system, λ0, are the longitude and latitude of the survey ship in the geodetic coordinate system, enu represents a local spatial rectangular coordinate system whose origin is the survey ship position x0, y0, z0, e represents the east component of the satellite in the enu coordinate system (positive when pointing to the east), n represents the east component of the satellite in the enu coordinate system (positive when pointing to the north), and u represents the east component of the satellite in the enu coordinate system (positive when pointing to the zenith);

[0023] 3) Use the measurement vessel’s attitude and other information to transform the target’s coordinates in the local rectangular coordinate system into the USB measurement coordinate system:

[0024]

[0025] Where, Represents the Euler angle rotation matrix between the USB device and the inertial navigation device. Represents the Euler angle rotation matrix of the hull attitude, dx, dy, dz represent the position deviation between the USB device and the inertial navigation device;

[0026] 4) Calculate the theoretical azimuth angle A of the USB tracking target at the corresponding moment t , pitch angle E t :

[0027]

[0028] 5) Calculate the difference between the measured azimuth and elevation angles and the theoretical azimuth and elevation angles:

[0029]

[0030] 6) USB axis parameter calibration:

[0031] Substitute sin(AA) in formulas (1) and (2) m ) and cos(AA m ) to linearize the nonlinear problem and record

[0032] K=β m ·cos(A m )M=β m ·sin(A m ) (7)

[0033] Substituting formula (7) into formulas (1) and (2), we can obtain

[0034] E=E c -K·cos(A)-M·sinA-C e -ΔE Z -ΔE g ·cosE (8)

[0035] A=A c -tanE·[M·sinA-K·cosA]-δ m tanE-S b ·secE-C S ·secE-ΔA Z ·secE(9)

[0036] The axis parameter x is taken as the unknown quantity, that is,

[0037] x=[A0 E0 KM δ m S b ] T (10)

[0038] According to the measured data and the Beidou satellite theoretical orbit calculation results, the error equation can be constructed:

[0039] V=Ax-l (11)

[0040] Where A represents the design matrix; V represents the vector of the measured azimuth and pitch angles and the theoretical azimuth and pitch angles; x represents the axis system parameter to be solved; and l represents the difference between the measured and theoretical calculated values.

[0041] Compared with the prior art, the advantages of the present invention are:

[0042] The present invention provides a shipborne USB shaft system parameter calibration scheme based on the Beidou system. The scheme fully utilizes the advantages of Beidou satellite resources, such as abundant resources, uniform distribution, consistent frequency, and real-time acquisition of orbit information, as well as advantageous conditions such as the 360-degree steering capability of ships, thereby improving the efficiency and reliability of USB shaft system parameter calibration. Model establishment and calibration can be carried out in dynamic or static conditions, reducing the restrictions of external objective conditions on model establishment. Compared with low-orbit calibration satellites, the Beidou satellite orbit is higher, so a more precise theoretical angle reference can be obtained. In theory, the shipborne USB shaft system parameter calibration scheme based on the Beidou system can obtain more precise shaft system parameters. Theoretical azimuth and pitch angles are obtained by using satellite ephemeris and ship position information, and a USB angle measurement error correction model can be established without the need for auxiliary tracking of other equipment, thereby having high practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the calibration method for a ship capable of 360° steering.

[0044] Figure 2 It is a schematic diagram of the calibration method for ships sailing along fixed routes.

[0045] Figure 3 This is the calibration flow chart of shipborne USB shafting parameters based on the BeiDou system. DETAILED DESCRIPTION

[0046] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0047] like Figure 1 As shown, this embodiment provides a USB axis system parameter calibration method based on the BeiDou system. According to the USB angle measurement axis system parameter correction formula, a USB angle measurement error correction model can be obtained.

[0048] E=E c -β m ·cos(AA m )-C e -ΔE Z -ΔE g ·cosE (1)

[0049] A=A c -β m ·tanE·sin(AAm )-δ m tanE-S b ·secE-C S ·secE-ΔA Z ·secE (2)

[0050] Where, the pitch angle after axis error correction, E c The pitch angle after ground zero correction, A The azimuth angle after axis system error correction, A c Azimuth after ground zero correction, β m The maximum tilt of the disk is not horizontal, A m The maximum tilt direction of the disk is not horizontal; C S Antenna photoelectric axis is not matched laterally, C e Antenna photoelectric axis longitudinal mismatch, ΔA Z Azimuth dynamic hysteresis, ΔE Z Pitch dynamic hysteresis, ΔE g Gravity sag, δ m The pitch axis and azimuth axis are not orthogonal, S b The pitch axis and the optical axis are not orthogonal, A c =A usb -A0,E c =E usb -E0,A usb and E usb are the measured values ​​of USB azimuth and pitch angles, A0 and E0 are the azimuth zero position and pitch zero position. The specific steps of USB axis system parameter calibration based on the above USB angle measurement error correction model are as follows:

[0051] 1) Carry out BeiDou satellite visibility forecast and judge whether the time period meets the optimal observation conditions for USB axis parameter calibration. In the case that the ship can turn 360 degrees, the judgment standard for the optimal observation conditions for USB axis parameter calibration is that there are at least 3 BeiDou satellites with an elevation angle of 20 degrees to 60 degrees in the tracking period, and they are evenly distributed, such as Figure 1 As shown in the figure; when the ship is sailing on a fixed route, the criterion for judging the optimal observation conditions for USB axis parameter calibration is that the BeiDou satellite elevation angle is within the range of 20° to 60° within the tracking period and at least 40 to 50 BeiDou satellites can be tracked, and the tracked BeiDou satellites are evenly distributed in each quadrant, as shown in the figure. Figure 2 shown.

[0052] 2) Use the shipborne USB device to track BeiDou satellites and obtain USB observation data. Use the default or initial axis system parameters and use formulas (1) and (2) to obtain the USB measured azimuth and pitch angle data.

[0053] 3) Using the survey ship and BeiDou satellite position information, the position vector enu of the BeiDou satellite in the local rectangular coordinate system can be calculated:

[0054]

[0055] Among them, x, y, z are the positions of the satellite in the spatial rectangular coordinate system, x0, y0, z0 are the positions of the survey ship in the spatial rectangular coordinate system, λ0, are the longitude and latitude of the survey vessel in the geodetic coordinate system. enu represents a local rectangular coordinate system whose origin is the survey vessel position x0, y0, z0. e represents the easting component of the satellite in the enu coordinate system (positive when pointing east), n represents the easting component of the satellite in the enu coordinate system (positive when pointing north), and u represents the easting component of the satellite in the enu coordinate system (positive when pointing toward the zenith).

[0056] 4) Use the measurement vessel’s attitude and other information to convert the target’s coordinates in the local rectangular coordinate system to the USB measurement coordinate system:

[0057]

[0058] Where, Represents the Euler angle rotation matrix between the USB device and the inertial navigation device. Represents the Euler angle rotation matrix of the hull attitude, and dx, dy, and dz represent the position deviation between the USB device and the inertial navigation device.

[0059] 5) Calculate the theoretical azimuth angle A of the USB tracking target at the corresponding moment t , pitch angle E t :

[0060]

[0061] 6) Calculate the difference between the measured azimuth and elevation angles and the theoretical azimuth and elevation angles:

[0062]

[0063] 7) USB axis parameter calibration:

[0064] Substitute sin(AA) in formulas (1) and (2) m ) and cos(AA m ) to linearize the nonlinear problem and record

[0065] K=β m ·cos(A m )M=β m ·sin(A m ) (7)

[0066] Substituting formula (7) into formulas (1) and (2), we can obtain

[0067] E=E c -K·cos(A)-M·sinA-C e -ΔE Z -ΔE g ·cosE (8)

[0068] A=A c -tanE·[M·sinA-K·cosA]-δ m tanE-S b ·secE-C S ·secE-ΔA Z ·secE(9)

[0069] The axis parameter x is taken as the unknown quantity, that is,

[0070] x=[A0 E0 KM δ m S b ] T (10)

[0071] According to the measured data and the Beidou satellite theoretical orbit calculation results, the error equation can be constructed:

[0072] V=Ax-l (11)

[0073] Where A represents the design matrix; V represents the vector of the measured azimuth and pitch angles and the theoretical azimuth and pitch angles; x represents the axis system parameter to be solved; and l represents the difference between the measured and theoretical calculated values.

[0074] 8) Track BeiDou satellites in other time periods and use formula (1) to verify the correctness of the model.

[0075] In addition to the above embodiments, the present invention also includes other implementation methods. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of protection of the claims of the present invention.

Claims

1. A USB axis parameter calibration method based on the BeiDou system, characterized by: The method comprises the following steps: Step 1: Obtain Beidou satellite ephemeris data; Step 2: Carry out BeiDou satellite visibility forecast and determine whether the time period meets the optimal observation conditions for USB shaft system parameter calibration. When the ship can turn 360°, the judgment standard for the optimal observation conditions for USB shaft system parameter calibration is that during the tracking period, there are at least three BeiDou satellites with elevation angles ranging from 20° to 60°, and they are evenly distributed. When the ship sails on a fixed route, the judgment standard for the optimal observation conditions for USB shaft system parameter calibration is that during the tracking period, at least 40 to 50 BeiDou satellites can be tracked with elevation angles ranging from 20° to 60°, and the tracked BeiDou satellites are evenly distributed in each quadrant. Step 3: Develop a USB tracking BeiDou satellite plan; Step 4: Generate USB system boot data using satellite ephemeris data and survey vessel position information according to the USB BeiDou satellite tracking solution; Step 5: Guide the USB device to track BeiDou satellites according to the boot data; Step 6: Based on the USB angle measurement error correction model and the relevant data recorded in step 5, the USB axis parameters are obtained; Step 7: Track BeiDou satellites in other time periods to test and verify the accuracy of USB axis system parameters.

2. The USB axis parameter calibration method based on the BeiDou system according to claim 1, characterized in that: The USB angle measurement error correction model in step 6 is: E=E c -b m ·cos(AA m )-C e -NO Z -NO g ·cosE (1) A=A c -β m ·tanE·sin(AA m )-δ m ·tanE-S b ·secE-C S ·secE-ΔA Z ·secE (2) Where, the pitch angle after axis error correction, E c The pitch angle after ground zero correction, A The azimuth angle after axis system error correction, A c Azimuth after ground zero correction, β m The maximum tilt of the disk is not horizontal, A m The maximum tilt direction of the disk is not horizontal; C S Antenna photoelectric axis is not matched laterally, C e Antenna photoelectric axis longitudinal mismatch, ΔA Z Azimuth dynamic hysteresis, ΔE Z Pitch dynamic hysteresis, ΔE g Gravity sag, δ m The pitch axis and azimuth axis are not orthogonal, S b The pitch axis and the optical axis are not orthogonal, A c =A usb -A0,E c =E usb -E0,A usb and E usb are the measured values ​​of USB azimuth and elevation angles, A0 and E0 are the azimuth zero position and elevation zero position.

3. The USB axis parameter calibration method based on the BeiDou system according to claim 2, characterized in that: The method for obtaining the USB axis system parameters according to the USB angle measurement error correction model in step 6 includes the following steps: 1) Use the shipborne USB device to track BeiDou satellites and obtain USB observation data. Use the default or initial axis system parameters and use formulas (1) and (2) to obtain the USB measured azimuth and pitch angle data. 2) Using the survey ship and BeiDou satellite position information, the position vector enu of the BeiDou satellite in the local rectangular coordinate system can be calculated: Among them, x, y, z are the positions of the satellite in the spatial rectangular coordinate system, x0, y0, z0 are the positions of the survey ship in the spatial rectangular coordinate system, λ0, is the longitude and latitude of the survey ship in the geodetic coordinate system, enu represents a local space rectangular coordinate system whose coordinate origin is the survey ship position x0, y0, z0, e represents the east component of the satellite in the enu coordinate system, n represents the east component of the satellite in the enu coordinate system, and u represents the east component of the satellite in the enu coordinate system; 3) Use the measurement vessel’s attitude and other information to transform the target’s coordinates in the local rectangular coordinate system into the USB measurement coordinate system: Where, Represents the Euler angle rotation matrix between the USB device and the inertial navigation device. Represents the Euler angle rotation matrix of the hull attitude, dx, dy, dz represent the position deviation between the USB device and the inertial navigation device; 4) Calculate the theoretical azimuth angle A of the USB tracking target at the corresponding moment t , pitch angle E t : 5) Calculate the difference between the measured azimuth and elevation angles and the theoretical azimuth and elevation angles: 6) USB axis parameter calibration: Substitute sin(AA) in formulas (1) and (2) m ) and cos(AA m ) to linearize the nonlinear problem and record K=β m ·cos(A m ) M=β m ·sin(A m ) (7) Substituting formula (7) into formulas (1) and (2), we can obtain E=E c -K cos(A)-M sinA-C e -ΔE Z -ΔE g ·cosE (8) A=A c -tanE·[M·sinA-K·cosA]-δ m ·tanE-S b ·secE-C S ·secE-ΔA Z ·secE (9) The axis parameter x is taken as the unknown quantity, that is, x=[A0 E0 KM d m S b ] Τ (10) According to the measured data and the Beidou satellite theoretical orbit calculation results, the error equation can be constructed: V=Ax-l (11) Where A represents the design matrix; V represents the vector of the measured azimuth and pitch angles and the theoretical azimuth and pitch angles; x represents the axis system parameter to be solved; and l represents the difference between the measured and theoretical calculated values.

Images