Strap-down inertial navigation system-level calibration method based on temperature control double-shaft position turntable

Abstract

The invention provides a strapdown inertial navigation system-level calibration method based on a temperature-control double-shaft position turntable, and overcomes the defects of high workload, easiness in making mistakes, high cost, waste of equipment and manpower and the like in the conventional calibration method. The invention provides temperature and position calibration based on a temperature control double-shaft position rotary table, the transposition limitation of the double-shaft rotary table is overcome, a rotating position and a rotating scheme are designed in a targeted manner, and meanwhile, automatic position calibration of a gyroscope and an accelerometer of a product is realized through automatic transposition of the rotary table. The method can control the temperature of the rotary table incubator, automatically identify the corresponding temperature point of the product, capture the error parameter of the product at the corresponding temperature point, and automatically solve the compensation values of the zero positions of the gyroscope and the accelerometer along with the initial temperature change.

Description

Technical Field

[0001] The invention belongs to the technical field of inertial navigation calibration, and in particular relates to a strapdown inertial navigation system-level calibration method based on a temperature-controlled dual-axis position turntable. Background Art

[0002] Inertial navigation / heading attitude products can measure and output the aircraft's heading, pitch, roll, longitude, latitude, altitude, eastward speed, northward speed, celestial speed and other navigation information in real time, and output the aircraft's three-axis angular rate and three-axis acceleration signals at the same time. Inertial navigation / heading attitude systems have the ability to provide high-precision autonomous navigation, output multiple information parameters, and maintain accuracy for a long time. They are the information basis of weapon systems and flight control systems, and are therefore often regarded as the most important navigation equipment.

[0003] Before using the inertial navigation / heading attitude products, the error parameters of the gyroscope and accelerometer must be determined through calibration tests and compensated in the inertial navigation system. The commonly used position calibration method is three-axis calibration. The calibration process requires manual operation of software to achieve the transformation of each position. This calibration method has high requirements for operators, huge workload, and is prone to errors. After the error occurs, it can only be solved by recalibration. At the same time, the current temperature calibration requires the operator to manually model and calculate the temperature compensation parameters based on a large amount of gyroscope and accelerometer data collected from low temperature to high temperature. The workload is large and the efficiency is low. It is easy to make mistakes and the inertial navigation performance cannot meet the requirements. After the error occurs, the temperature calibration and calculation verification need to be re-performed, which wastes a lot of equipment and human resources and delays the production cycle.

[0004] Therefore, it is necessary to explore a new strapdown inertial navigation system-level calibration method. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of the existing calibration methods, such as large workload, easy errors, high cost, waste of equipment and manpower, etc., and to provide a strapdown inertial navigation system-level calibration method based on a temperature-controlled dual-axis position turntable.

[0006] The concept of the present invention:

[0007] In view of the problems existing in the existing calibration methods, the present invention has conducted research and comparison, and found that the dual-axis turntable with the same precision not only has advantages in economy and site occupation compared with the three-axis turntable, but also can cover the combination of speed and attitude in the calibration process of existing products, and can completely replace the three-axis calibration scheme. Therefore, in order to simplify the calibration equipment and reduce the calibration cost, the present invention intends to carry out research on temperature and dual-axis turntable automatic calibration technology based on the temperature-controlled dual-axis position turntable to realize the inertial navigation / heading attitude temperature and dual-axis fully automatic calibration.

[0008] Based on the above invention concept, in order to achieve the above purpose, the technical solution provided by the present invention is:

[0009] A strapdown inertial navigation system-level calibration system based on a dual-axis position turntable, which is special in that it includes a temperature-controlled dual-axis position turntable, a mounting bracket, a calibration fixture, cables, a test fixture, and a main control computer;

[0010] The temperature-controlled dual-axis position turntable has two mutually perpendicular rotation axes, which provides a high-precision attitude basis for the calibration and testing of the inertial navigation system; the turntable is the core of the calibration system and is mainly used for the temperature calibration test and position rotation test of the inertial navigation system;

[0011] The calibration fixture is installed on the turntable surface of the temperature-controlled dual-axis position turntable inner frame to provide an installation positioning reference for the inertial navigation system;

[0012] The mounting bracket is used to fix the inertial navigation system on the calibration fixture;

[0013] The inertial navigation system is connected to the main control computer through cables and test fixtures in turn, wherein the test fixture is used to perform signal transmission (specifically, signal transfer between the inertial navigation system and the main control computer), and control the power on and off of the inertial navigation system and state switching (the state here only refers to the test state or calibration state);

[0014] The main control computer is used for inertial navigation system testing, controlling the entire calibration process, temperature-controlled dual-axis position turntable rotation, data acquisition and solution. That is to say, the main control computer has an automatic calibration function, which is used to control the temperature-controlled dual-axis position turntable to realize the dual-axis position rotation of the inertial navigation system, control the temperature of the temperature-controlled dual-axis position turntable, automatically calibrate the position of the dual-axis turntable of the inertial navigation system, automatically identify the temperature point of the temperature box, read and solve the error parameters of the current temperature point to realize automatic temperature calibration.

[0015] At the same time, the present invention provides a strapdown inertial navigation system-level calibration method based on a dual-axis position turntable, and the strapdown inertial navigation system-level calibration system based on the dual-axis position turntable is used to realize automatic dual-axis position calibration, temperature calibration and system error compensation of the inertial navigation system. The specific steps are as follows:

[0016] 1) According to the structure of the strapdown inertial navigation system-level calibration system based on the dual-axis position turntable, the calibration fixture is first installed on the turntable table of the temperature-controlled dual-axis position turntable incubator inner frame, and then the inertial navigation system to be calibrated is fixed on the calibration fixture through the mounting bracket;

[0017] 2) The main control computer controls the temperature-controlled dual-axis position turntable to rotate and perform initial positioning of the inertial navigation system;

[0018] 3) Temperature calibration

[0019] 3.1) After the main control computer controls the inertial navigation system to power on and enter the calibration state, the main control computer controls the temperature-controlled dual-axis position turntable to perform temperature calibration tests on the inertial navigation system at different temperatures, and collects the original pulse data of the gyro and accelerometer of the inertial navigation system at each temperature;

[0020] 3.2) Using the data collected in step 3.1), automatically perform parameter compensation in the full temperature range according to the segmented curve fitting model, and write the temperature compensation parameters into the inertial navigation system;

[0021] Because the output of the gyroscope and accelerometer changes nonlinearly with temperature, before calibrating the gyroscope and accelerometer, it is necessary to process the original pulse data of the gyroscope and accelerometer at different temperatures, calculate the relationship between the output pulse value of the gyroscope and accelerometer and the initial startup temperature and temperature change, that is, calculate the corresponding temperature zero deviation compensation and temperature change rate deviation compensation to avoid the influence of temperature on the calibration of the accelerometer and gyroscope.

[0022] 4) Calibration and parameter calculation

[0023] Specifically including accelerometer position calibration and parameter solution and gyroscope calibration and parameter solution;

[0024] Among them, the accelerometer position calibration and parameter solution are specifically as follows:

[0025] ①. The main control computer controls the temperature-controlled dual-axis position turntable to rotate, so that the sensitive axes of the three accelerometers of the inertial navigation system point to nine positions: "Sky-West-South", "Earth-West-North", "Earth-East-South", "East-Sky-South", "East-Earth-North", "West-Earth-South", "West-South-Sky", "West-North-Earth", and "East-South-Earth", and collect the output pulse values ​​of the accelerometers at each position in the same time period;

[0026] ②. Using the average value of 9 samples, calculate the zero position and scale factor of the accelerometer according to the accelerometer calibration principle;

[0027] The gyro calibration and parameter calculation are as follows:

[0028] Ⅰ. The main control computer controls the temperature-controlled dual-axis position turntable to rotate one circle clockwise and counterclockwise around the X-axis, Y-axis, and Z-axis respectively, and records the output pulse accumulation of the three-axis gyroscope of the inertial navigation system during the rotation process;

[0029] Ⅱ. Using the results of 6 samplings, the zero position and scale coefficient of the gyro are calculated according to the gyro calibration principle;

[0030] 5) Write the zero position and scale factor of the accelerometer and the zero position and scale factor of the gyroscope obtained in step 4) into the inertial navigation system parameter table to complete the calibration.

[0031] Furthermore, in step 2), the initial positioning means that the X-axis, Y-axis, and Z-axis of the inertial navigation system point to the east, north, and sky respectively.

[0032] Further, in step 3), different temperatures refer to -55°C, -40°C, -20°C, 0°C, 20°C, 40°C, 60°C and 70°C, that is, 8-point temperature calibration is performed; of course, 6-point temperature calibration can also be performed according to needs, such as: -40°C, -20°C, 0°C, 20°C, 40°C, 65°C.

[0033] Furthermore, in the accelerometer position calibration and parameter solution in step 4), the output pulse values ​​of the nine position accelerometers for 1 minute are collected respectively.

[0034] Advantages of the present invention:

[0035] 1. The present invention proposes a temperature and position calibration based on a temperature-controlled dual-axis position turntable, which not only overcomes the dual-axis turntable rotation limitation, but also specifically designs a rotation position and rotation scheme, and can also realize the automatic calibration of the product gyroscope and accelerometer position through the automatic rotation of the turntable. The present invention can also control the temperature of the turntable incubator, automatically identify the corresponding temperature points of the product and capture the product error parameters of the corresponding temperature points, and automatically solve the compensation value of the gyroscope and accelerometer zero position changing with the initial temperature. Compared with the original manual three-axis calibration method, this calibration method has the advantages of high efficiency and high degree of automation. It is suitable for the automatic calibration of inertial navigation products, can avoid calibration rework caused by human factors, and significantly improve the efficiency of inertial navigation / heading attitude calibration.

[0036] 2. The present invention establishes a dual-axis gyroscope and accelerometer calibration model, automatically controls the temperature-controlled dual-axis turntable to turn to the specified position, and reads in the temperature point judgment during temperature calibration, realizes the collection and solution of different temperature points and position data, automatically completes the parameter calibration and compensation of the inertial navigation system, realizes the temperature and position calibration compensation of the inertial navigation product, and improves the navigation accuracy of the inertial navigation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the strapdown inertial navigation system-level calibration connection of the dual-axis position turntable;

[0038] The accompanying drawings are marked as follows:

[0039] 1- Temperature-controlled dual-axis position turntable; 2- Inertial navigation system; 3- Mounting bracket; 4- Calibration fixture; 5- Cable; 6- Test tooling, 7- Main control computer, 8- Main control computer switch; 9- Socket; 10- Main power switch, 11- Turntable table; 12- Turntable power switch; 13- 28V power conversion. DETAILED DESCRIPTION

[0040] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0041] like Figure 1 As shown, the strapdown inertial navigation system-level calibration system based on the dual-axis position turntable includes a temperature-controlled dual-axis position turntable, a mounting bracket, a calibration fixture, a cable, a test fixture, and a main control computer. The temperature-controlled dual-axis position turntable has two mutually perpendicular rotation axes, which provide a high-precision attitude basis for the calibration and testing of the inertial navigation system; the calibration fixture is installed on the turntable table of the temperature-controlled dual-axis position turntable temperature box inner frame, and provides an installation positioning reference for the inertial navigation system, which is "seeking north" in this embodiment. No matter where the temperature-controlled dual-axis position turntable is placed, the calibration fixture can be used to provide an installation reference for the inertial navigation system; the mounting bracket is used to fix the inertial navigation system on the calibration fixture; the inertial navigation system is connected to the main control computer through cables and test fixtures in turn, wherein the test fixture is used to transmit signals and control the power on and off and state switching of the inertial navigation system; the main control computer is used for inertial navigation system testing, controlling the entire calibration process, the temperature-controlled dual-axis position turntable rotation, data acquisition and solution. Among them, the technical personnel in this field are well aware of how to implement the switch assembly of each component and the power conversion setting, which will not be elaborated here.

[0042] The method for calibrating the inertial navigation system using the above calibration system includes the following steps:

[0043] 1) First, install the calibration fixture on the turntable table of the temperature-controlled dual-axis position turntable incubator inner frame, and then fix the inertial navigation system to be calibrated on the calibration fixture through the mounting bracket;

[0044] 2) The main control computer controls the temperature-controlled dual-axis position turntable to rotate to perform initial positioning of the inertial navigation system; due to the structural limitation of the turntable, the inertial navigation system can only realize a clockwise and counterclockwise rotation of the Z gyro pointing to the sky, while the X gyro or the Y gyro cannot rotate around its sensitive axis when pointing to the sky. Therefore, in this embodiment, the initial positioning refers to the X-axis, Y-axis, and Z-axis of the inertial navigation system pointing to the east, north, and sky respectively;

[0045] 3) Temperature calibration

[0046] 3.1) After the main control computer controls the inertial navigation system to power on and enter the calibration state, the main control computer controls the temperature-controlled dual-axis position turntable to perform temperature calibration tests on the inertial navigation system at different temperatures (eight temperature points: -55°C, -40°C, -20°C, 0°C, 20°C, 40°C, 60°C and 70°C), and collects the original pulse data of the gyro and accelerometer of the inertial navigation system at each temperature;

[0047] 3.2) Using the data collected in step 3.1), according to the piecewise curve fitting model, parameter compensation is automatically performed in the full temperature range, and the temperature compensation parameters are written into the inertial navigation system;

[0048] 4) Calibration and parameter calculation

[0049] Specifically including accelerometer position calibration and parameter solution and gyroscope calibration and parameter solution;

[0050] Among them, the accelerometer position calibration and parameter solution are specifically as follows:

[0051] ①. The main control computer controls the temperature-controlled dual-axis position turntable to rotate, so that the sensitive axes of the three accelerometers of the inertial navigation system point to the nine positions of "sky-west-south", "ground-west-north", "ground-east-south", "east-sky-south", "east-ground-north", "west-ground-south", "west-south-sky", "west-north-ground", and "east-south-ground" (that is, through specific permutations and combinations, the sensitive axis of each accelerometer of the inertial navigation system can be calibrated), and the output pulse value of the accelerometer at each position for 1 minute is collected respectively;

[0052] Due to the particularity of the dual-axis position turntable, the accelerometer position calibration is performed by combining and controlling the X-axis and Z-axis of the dual-axis turntable to make the inertial navigation system point to the above nine positions. The initial positions of the dual-axis turntable at each position are shown in Table 1:

[0053] Table 1 Initial position of the double-axis turntable with nine-position calibration

[0054]

[0055] ②. Using the average value of 9 samples, calculate the zero position and scale factor of the accelerometer according to the accelerometer calibration principle;

[0056] The gyro calibration and parameter calculation are as follows:

[0057] Ⅰ. The main control computer controls the temperature-controlled dual-axis position turntable to rotate one circle clockwise and counterclockwise around the X-axis, Y-axis, and Z-axis respectively, and records the output pulse accumulation of the three-axis gyroscope of the inertial navigation system during the rotation process;

[0058] Due to the structural limitation of the turntable, the inertial navigation system can only realize the Z gyro pointing to the sky and rotating clockwise or counterclockwise for one circle, while the X gyro or Y gyro cannot rotate around its sensitive axis when pointing to the sky. Therefore, the initial position of the turntable and the rotation axis of the turntable need to be adjusted as follows:

[0059] When the X-axis rotates, the initial position is adjusted from "X points to the sky" and "X points to the sky counterclockwise" to "X points to the north" and "X points to the north counterclockwise" around the outer frame of the three-axis turntable for one rotation around the X-axis of the dual-axis turntable; when the Y-axis rotates, the initial position is adjusted from "Y points to the sky" and "Y points to the sky counterclockwise" to "Y points to the north" and "Y points to the north counterclockwise" around the outer frame of the three-axis turntable for one rotation around the X-axis of the dual-axis turntable.

[0060] The initial position and rotation axis of the dual-axis turntable during gyro calibration are shown in Table 2.

[0061] Table 2 Initial position and rotation axis of the dual-axis turntable for gyro calibration

[0062]

[0063] Ⅱ. Using the results of 6 samplings, the zero position and scale coefficient of the gyro are calculated according to the gyro calibration principle;

[0064] 5) Write the zero position and scale factor of the accelerometer and the zero position and scale factor of the gyroscope obtained in step 4) into the inertial navigation system parameter table to complete the calibration.

[0065] After verification, this method can realize the calculation and automatic writing of the calibration parameters of the gyro and accelerometer position and temperature of the inertial navigation system. The calibration results are shown in Table 3:

[0066] Table 3 Calibration parameters

[0067]

[0068]

[0069]

[0070] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be included in the protection scope of the present invention.

Claims

1. A strapdown inertial navigation system-level calibration system based on a dual-axis position turntable, characterized in that: Includes temperature-controlled dual-axis position turntable, mounting bracket, calibration fixture, cables, test fixture and main control computer; The temperature-controlled dual-axis position turntable has two mutually perpendicular rotation axes, providing a high-precision attitude basis for inertial navigation system calibration and testing; The calibration fixture is installed on the turntable surface of the temperature-controlled dual-axis position turntable incubator inner frame to provide an installation positioning reference for the inertial navigation system; The mounting bracket is used to fix the inertial navigation system on the calibration fixture; The inertial navigation system is connected to the main control computer via cables and a test fixture in sequence, wherein the test fixture is used to transmit signals and control the power on and off and state switching of the inertial navigation system; The main control computer is used for inertial navigation system testing, controlling the entire calibration process, temperature-controlled dual-axis position turntable rotation, data acquisition and solution.

2. A strapdown inertial navigation system-level calibration method based on a dual-axis position turntable, characterized in that: Here are the steps: 1) According to the structure of the strapdown inertial navigation system-level calibration system based on the dual-axis position turntable of claim 1, firstly install the calibration fixture on the turntable table of the temperature-controlled dual-axis position turntable incubator inner frame, and then fix the inertial navigation system to be calibrated on the calibration fixture through the mounting bracket; 2) The main control computer controls the temperature-controlled dual-axis position turntable to rotate and perform initial positioning of the inertial navigation system; 3) Temperature calibration 3.1) After the main control computer controls the inertial navigation system to power on and enter the calibration state, the main control computer controls the temperature-controlled dual-axis position turntable to perform temperature calibration tests on the inertial navigation system at different temperatures, and collects the original pulse data of the gyro and accelerometer of the inertial navigation system at each temperature; 3.2) Using the data collected in step 3.1), according to the piecewise curve fitting model, parameter compensation is automatically performed in the full temperature range, and the temperature compensation parameters are written into the inertial navigation system; 4) Calibration and parameter calculation Specifically including accelerometer position calibration and parameter solution and gyroscope calibration and parameter solution; Among them, the accelerometer position calibration and parameter solution are specifically as follows: ①. The main control computer controls the temperature-controlled dual-axis position turntable to rotate, so that the sensitive axes of the three accelerometers of the inertial navigation system point to nine positions: "sky-west-south", "ground-west-north", "ground-east-south", "east-sky-south", "east-ground-north", "west-ground-south", "west-south-sky", "west-north-ground", and "east-south-ground", and collect the output pulse values ​​of the accelerometers at each position in the same time period; ②. Using the average value of 9 samples, calculate the zero position and scale factor of the accelerometer according to the accelerometer calibration principle; The gyro calibration and parameter calculation are as follows: Ⅰ. The main control computer controls the temperature-controlled dual-axis position turntable to rotate one circle clockwise and counterclockwise around the X-axis, Y-axis, and Z-axis respectively, and records the output pulse accumulation of the three-axis gyroscope of the inertial navigation system during the rotation process; Ⅱ. Using the results of 6 samplings, the zero position and scale coefficient of the gyro are calculated according to the gyro calibration principle; 5) Write the zero position and scale factor of the accelerometer and the zero position and scale factor of the gyroscope obtained in step 4) into the inertial navigation system parameter table to complete the calibration.

3. The strapdown inertial navigation system-level calibration method based on a dual-axis position turntable according to claim 2, characterized in that: In step 2), the initial positioning means that the X-axis, Y-axis, and Z-axis of the inertial navigation system point to the east, north, and sky respectively.

4. The strapdown inertial navigation system-level calibration method based on a dual-axis position turntable according to claim 3, characterized in that: In step 3), different temperatures refer to -55°C, -40°C, -20°C, 0°C, 20°C, 40°C, 60°C and 70°C.

5. The strapdown inertial navigation system-level calibration method based on a dual-axis position turntable according to claim 4, characterized in that: In step 4), in the accelerometer position calibration and parameter solution, the output pulse values ​​of the nine position accelerometers for 1 minute are collected respectively.

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