A dock calibration method based on theodolite

Abstract

The present invention relates to a dock calibration method based on a theodolite, comprising the following steps: 1. establishing a mathematical model to determine error terms; 2. clarifying a calibration method for individual errors based on the error terms; 3. calibrating electrical equipment using the theodolite as a reference and a joint measurement method thereof according to the individual error calibration method to obtain individual differences; and 4. aligning the error orientations according to the mathematical model. This method solves the problem of dock calibration of electrical equipment without mechanical axis replacement. By using a high-precision theodolite as a reference and performing data exchange according to the deck system, calibration accuracy is guaranteed, thus having important practical significance.

Description

Technical Field

[0001] The present invention relates to a dock calibration method based on a theodolite, belonging to the field of measurement, control and communication. Background Art

[0002] In-dock calibration refers to the coordinated implementation of the dock, shipbase, electrical equipment, calibration facilities, and geodetic surveying to determine the error model parameters and coordinate system alignment of each electrical device while the shipbase platform is docked. The definition of in-dock calibration indicates that its primary purpose is to obtain the error model parameters of the electrical devices and to align the coordinate system (establish a unified coordinate system). Electrical devices track space targets. Because their electrical axes are "imaginary" axes, optical axes are typically used in place of mechanical axes. After the electrical axes are aligned parallel to the optical axes, individual errors are calibrated according to the error model to achieve coordinate system alignment. Coordinate system alignment is divided into azimuth and horizontal alignment. Horizontal alignment is ensured by geodetic surveying, while azimuth alignment utilizes error models. The azimuth alignment datum is the bow-stern line, with all devices aligned to it. While established and effective methods exist for the calibration of electrical devices equipped with optical axes, calibration of electrical devices without optical axes remains a relatively new field.

[0003] The present invention designs a dock calibration method based on theodolite. By establishing a mathematical model, the calibration of single-item differences adopts a method of joint measurement of electrical equipment and theodolite, that is, the theodolite is used as a calibration standard to complete the orientation alignment work, providing a practical and simple method for solving this problem. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a dock calibration method based on the above-mentioned existing technology, which uses the theodolite as a reference. After the theodolite is calibrated and corrected using conventional azimuth mark and star alignment methods, it is used as a reference to simultaneously track fixed targets in a cascade manner, and the single error of the electrical equipment is obtained in the relative position relationship given by the results of geodetic measurement.

[0005] The technical solution adopted by the present invention to solve the above problem is: a dock calibration method based on theodolite, which is implemented as follows:

[0006] 1) Establish a mathematical model

[0007] A system error model is established for the error source of electrical equipment. First, a quantitative description of the system error is given, and then the system error correction is completed through error parameter calibration and adjustment. The error correction model is as follows:

[0008] A=A c +A0+β m sin(A c -Am )tanE c +δ m tgE c +(K z +ΔU A / μ A )secE c

[0009] E=E c +E0+β m cos(A c -A m )+K n +ΔE g cosE c +ΔU E / μ E +ΔE d

[0010] Where: A is the true value of the azimuth; A c is the azimuth measurement value; A0 is the azimuth zero position; ΔU A is the azimuth error voltage during self-tracking; μ A is the directional sensitivity of the azimuth branch; K z is the azimuth error caused by the mismatch of the electromechanical axis; E is the true value of the pitch angle; E c is the measured value of the pitch angle; E0 is the pitch zero position; K n is the pitch error caused by the mismatch of the electromechanical axis; ΔE g is the gravity sag error; ΔU E is the pitch error voltage during self-tracking; μ E is the directional sensitivity of the pitch branch; ΔE d is the radio wave refraction error;

[0011] 2) Determine the calibration method for electrical equipment error items

[0012] Directly use the theodolite's azimuth angle of 0° as the reference for coordinate alignment, ensuring that all equipment data is entered in the deck system. After the theodolite completes error calibration and correction according to the standard calibration method, it is connected with the electrical equipment to complete the electrical equipment error calibration. The error items that need to be calibrated are A0 and K z Calibration, E0 and K n Calibration;

[0013] 3) Adjustment of the electric axis of the parabolic antenna

[0014] Under far-field conditions, an electrical signal for electrical equipment tracking and an optical signal for theodolite tracking are set on the calibration tower. The theodolite tracks the optical target, and its angle value is converted into the azimuth and elevation angle of the electrical signal with the mechanical axis of the electrical equipment according to the geodetic measurement results. The electrical equipment antenna is fixed and the antenna amplitude is adjusted to ensure that the electrical axis is parallel to the mechanical axis.

[0015] 4) A0 and K z Calibration

[0016] Under far-field conditions, the calibration tower is set up with electrical signals for electrical equipment tracking and optical signals for theodolite tracking, which are horizontally projected onto the deck system. Through geodetic measurement and conversion, the A0 of the electrical equipment can be obtained.

[0017] A0=A c -A 标

[0018] At the same time, geodetic measurement can give the theoretical azimuth from the center of the three axes to the electric mark, and the difference between the actual measured value and the azimuth can be obtained by dividing the difference by secE. z , where E is the elevation angle of the antenna;

[0019] 5) E0 and K n Calibration

[0020] Under far-field conditions, the calibration tower is set up with an electrical signal for electrical equipment tracking and an optical signal for theodolite tracking. They are horizontally projected onto the deck system, and the vertical line of the deck system is drawn. According to the trigonometric relationship, the E0 of the electrical equipment can be obtained:

[0021] E0=E c -E 标

[0022] At the same time, geodetic measurement can give the theoretical pitch angle from the three-axis center to the electric mark, and the difference between it and the actual measured value can be used to obtain K n+ ΔE g .

[0023] Preferably, the error sources in step 1) mainly include the non-leveling of the large disk, non-orthogonality of the two axes, azimuth zero position, pitch zero position and gravity droop, wherein the non-leveling of the large disk refers to the non-parallelism between the azimuth turntable plane and the inertial navigation deck system reference plane, which is usually represented by the maximum tilt βm and the maximum tilt direction Am; the non-orthogonality of the two axes means that the pitch axis is not perpendicular to the azimuth axis, which will cause azimuth angle error; azimuth zero position refers to the output value of the azimuth encoder when the mechanical axis is parallel to the normal of the azimuth reference mirror; pitch zero position refers to the output angle value of the pitch encoder when the pitch axis is parallel to the azimuth turntable plane.

[0024] Preferably, in step 4) A 标 Calculate using the following formula

[0025] A 标 =180-arcos((L OC -L AB -L OA cosθ) / L BC )

[0026] Where: L OC is the distance from the electrical equipment to the theodolite, L AB is the distance from the cursor to the electric mark, L OA is the distance from the cursor to the theodolite, L BC The distance from the electrical mark to the electrical equipment.

[0027] Preferably, in step 5), E 标 Calculate using the following formula

[0028] E 标 =arsin((L OA cosθ-D) / L BC )

[0029] Where: L OA is the distance from the cursor to the theodolite, D is the height difference between the theodolite and the three-axis center of the electrical equipment, L BC The distance from the electrical mark to the electrical equipment.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] (1) The method designed in the present invention solves the problem of dock calibration of electrical equipment without mechanical shaft replacement equipment.

[0032] (2) The method designed in the present invention solves the problem of adjusting the electric axis of parabolic electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention provides a flow chart of a dock calibration method based on a theodolite.

[0034] Figure 2 for Figure 1 The theodolite is connected with the electrical equipment to obtain the principle diagram of azimuth zero position.

[0035] Figure 3 for Figure 1 The theodolite and electrical equipment are connected to obtain the pitch zero position principle diagram. DETAILED DESCRIPTION

[0036] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0037] The present invention relates to a dock calibration method based on theodolite. The method uses theodolite as the whole ship's benchmark and uses a joint measurement method to complete the single-item difference calibration of electrical equipment based on geodetic survey results. The specific process is as follows:

[0038] 1. Derive the mathematical model

[0039] The main sources of error for electrical equipment include disk non-leveling, axis non-orthogonality, azimuth zero position, pitch zero position, and gravity droop. Establishing a system error model based on these error sources provides a quantitative description of the system error, which is then corrected through error parameter calibration and adjustment. Disk non-leveling refers to the non-parallelism between the azimuth turntable plane and the inertial navigation deck system reference plane, often expressed in terms of maximum tilt βm and maximum tilt direction Am. Axis non-orthogonality refers to the pitch axis not being perpendicular to the azimuth axis, which can cause azimuth angle error. Azimuth zero position refers to the output value of the azimuth encoder when the mechanical axis is parallel to the normal of the azimuth reference mirror. Pitch zero position refers to the angular value output by the pitch encoder when the pitch axis is parallel to the azimuth turntable plane.

[0040] According to the above error terms and error law analysis, the error correction model without loss of generality is as follows:

[0041] A=A c +A0+β m sin(A c -A m )tanE c +δ m tgE c +(K z +ΔU A / μ A )secE c

[0042] E=E c +E0+β m cos(A c -A m )+K n +ΔE g cosE c +ΔU E / μ E +ΔE d (2)

[0043] Where: A is the true value of the azimuth; A c is the azimuth measurement value; A0 is the azimuth zero position; ΔU A is the azimuth error voltage during self-tracking; μ A is the directional sensitivity of the azimuth branch; K z is the azimuth error caused by the mismatch of the electromechanical axis; E is the true value of the pitch angle; E cis the measured value of the pitch angle; E0 is the pitch zero position; K n is the pitch error caused by the mismatch of the electromechanical axis; ΔE g is the gravity sag error; ΔU E is the pitch error voltage during self-tracking; μ E is the directional sensitivity of the pitch branch; ΔE d is the radio wave refraction error.

[0044] 2. Determine the calibration method of electrical equipment error items

[0045] The theodolite is a conventional equipment on the ship-based platform. Its tracking accuracy is much greater than that of the electrical tracking equipment. It is used here as a calibration benchmark. When aligning the coordinates, the bow and stern lines are not used. Instead, the azimuth angle of the theodolite is directly used as the benchmark for coordinate alignment, ensuring that all equipment data is entered into the deck system. After the theodolite is calibrated and corrected according to the calibration method shown in the book "Calibration and Flight Calibration Technology of Measurement, Control and Communication Equipment of Space Measurement Ships", the electrical equipment error calibration is completed by joint measurement with the electrical equipment. The error items that need to be calibrated are A0 and K z Calibration, E0 and K n Calibration.

[0046] 3. Adjustment of the electric axis of parabolic antenna

[0047] Under far-field conditions, the calibration tower is set up with electrical signals for electrical equipment tracking and optical signals for theodolite tracking. The theodolite tracks the optical target, and its angle value is converted into the azimuth and pitch angle of the electrical signal pointed by the mechanical axis of the electrical equipment based on the geodetic measurement results. The antenna of the electrical equipment is fixed and the antenna amplitude is adjusted to ensure that the electrical axis is parallel to the mechanical axis.

[0048] 4. A0 and K z Calibration

[0049] Under far-field conditions, the calibration tower is set up with electrical signals for electrical equipment tracking and optical signals for theodolite tracking, which are projected horizontally onto the deck system. The principle is as shown in the attached figure. Figure 2 As shown. Through geodetic measurement and conversion, the lengths of AB, OC, CB, and OA can be accurately obtained. Draw a perpendicular line from A and B to OC, and use simple trigonometric formulas to obtain the A0 of the electrical equipment.

[0050] A0=A c -A 标

[0051] In order to overcome the error caused by the non-parallelism between AB line and OC line, A 标 Calculate using the following formula

[0052] A 标 =180-arcos((L OC -LAB -L OA cosθ) / L BC )

[0053] At the same time, geodetic measurement can provide the theoretical azimuth from the center of the three axes to the electric mark, and the difference between the theoretical azimuth and the actual measured value divided by secE can be used to obtain Kz.

[0054] 5. E0 and K n Calibration

[0055] Under far-field conditions, the calibration tower is set up with electrical signals for electrical equipment tracking and optical signals for theodolite tracking, which are projected horizontally onto the deck system. The principle is as shown in the attached figure. Figure 3 As shown. The vertical line of the gantry deck is used. According to the trigonometric relationship, the E0 of the electrical equipment can be obtained as follows:

[0056] E0=Ec-E 标

[0057] E 标 =arsin((L OA cosθ-D) / L BC )

[0058] Where: D is the height difference between the theodolite and the three-axis center of the electrical equipment.

[0059] At the same time, geodetic measurement can give the theoretical pitch angle from the three-axis center to the electric mark, and the difference between it and the actual measured value can be used to obtain K n+ ΔE g .

[0060] 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 dock calibration method based on a theodolite, characterized by: The method comprises the following steps: 1) Establish a mathematical model A system error model is established for the error source of electrical equipment. First, a quantitative description of the system error is given, and then the system error correction is completed through error parameter calibration and adjustment. The error correction model is as follows: A=A c +A0+b m sin(A c -A m )tanE c +d m tgE c +(K z +ΔU A / m A )secE c E=E c +E0+β m cos(A c -A m )+K n +ΔE g cosE c +ΔU E / m E +ΔE d Where: A is the true value of the azimuth; A c is the azimuth measurement value; A0 is the azimuth zero position; ΔU A is the azimuth error voltage during self-tracking; μ A is the directional sensitivity of the azimuth branch; K z is the azimuth error caused by the mismatch of the electromechanical axis; E is the true value of the pitch angle; E c is the measured value of the pitch angle; E0 is the pitch zero position; K n is the pitch error caused by the mismatch of the electromechanical axis; ΔE g is the gravity sag error; ΔU E is the pitch error voltage during self-tracking; μ E is the directional sensitivity of the pitch branch; ΔE d is the radio wave refraction error; β m Indicates the commonly used maximum tilt, A m Indicates the direction of maximum tilt; 2) Determine the calibration method for electrical equipment error items Directly use the theodolite's azimuth angle of 0° as the reference for coordinate alignment, ensuring that all equipment data is entered in the deck system. After the theodolite completes error calibration and correction according to the standard calibration method, it is connected with the electrical equipment to complete the electrical equipment error calibration. The error items that need to be calibrated are A0 and K z Calibration, E0 and K n Calibration; 3) Adjustment of the electric axis of the parabolic antenna Under far-field conditions, an electrical signal for electrical equipment tracking and an optical signal for theodolite tracking are set on the calibration tower. The theodolite tracks the optical target, and its angle value is converted into the azimuth and elevation angle of the electrical signal with the mechanical axis of the electrical equipment according to the geodetic measurement results. The electrical equipment antenna is fixed and the antenna amplitude is adjusted to ensure that the electrical axis is parallel to the mechanical axis. 4) A0 and K z Calibration Under far-field conditions, the calibration tower is set up with electrical signals for electrical equipment tracking and optical signals for theodolite tracking, which are horizontally projected onto the deck system. Through geodetic measurement and conversion, the A0 of the electrical equipment can be obtained. A0=A c -TO 标 At the same time, geodetic measurement can give the theoretical azimuth from the center of the three axes to the electric mark, and the difference between the actual measured value and the azimuth can be obtained by dividing the difference by secE. z , where E is the elevation angle of the antenna; A 标 Calculate using the following formula HAS 标 =180-arcos((L OC -L AB -L OA cosθ) / L BC ) Where: L OC is the distance from the electrical equipment to the theodolite, L AB is the distance from the cursor to the electric mark, L OA is the distance from the cursor to the theodolite, L BC The distance from the electrical mark to the electrical equipment; 5) E0 and K n Calibration Under far-field conditions, the calibration tower is set up with an electrical signal for electrical equipment tracking and an optical signal for theodolite tracking. They are horizontally projected onto the deck system, and the vertical line of the deck system is drawn. According to the trigonometric relationship, the E0 of the electrical equipment can be obtained: E0=E c -E 标 At the same time, geodetic measurement can give the theoretical pitch angle from the three-axis center to the electric mark, and the difference between it and the actual measured value can be used to obtain K n+ ΔE g ;E 标 Calculate using the following formula AND 标 =Arsine((L OA cosθ−D) / L BC ) Where: L OA is the distance from the cursor to the theodolite, D is the height difference between the theodolite and the three-axis center of the electrical equipment, L BC The distance from the electrical mark to the electrical equipment.

2. The method for dock calibration based on theodolite according to claim 1, characterized in that: The error sources in step 1) include the non-leveling of the large disk, non-orthogonality of the two axes, azimuth zero position, pitch zero position and gravity droop, wherein the non-leveling of the large disk refers to the non-parallelism between the azimuth turntable plane and the inertial navigation deck system reference plane, which is usually represented by the maximum tilt βm and the maximum tilt direction Am; the non-orthogonality of the two axes means that the pitch axis is not perpendicular to the azimuth axis, which will cause azimuth angle error; azimuth zero position refers to the output value of the azimuth encoder when the mechanical axis is parallel to the normal of the azimuth reference mirror; pitch zero position refers to the output angle value of the pitch encoder when the pitch axis is parallel to the azimuth turntable plane.

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