Fast Initial Alignment Aiding Device and Its Working Method

Abstract

The present invention relates to the field of inertial navigation technology, and particularly to a rapid initial alignment auxiliary device and its working method. Among them, the rapid initial alignment auxiliary device includes an auxiliary device main body, a circuit board, a biaxial MEMS accelerometer, a biaxial fiber optic gyroscope, a connector, and a card slot. The bottom end of the inner wall of the auxiliary device main body is fixedly installed with a circuit board, the upper end of the circuit board is fixedly installed with a biaxial MEMS accelerometer, the upper end of the inner wall of the auxiliary device main body is fixedly installed with a biaxial fiber optic gyroscope, the right end of the auxiliary device main body is fixedly connected with a connector, the lower end of the auxiliary device main body is fixedly connected with a card slot, and the right side of the card slot is adhesively connected with a main inertial navigation. Without changing the installation method and structure of the original inertial navigation device, the external auxiliary alignment device design of the present invention greatly improves the operation convenience. Secondly, the auxiliary device significantly shortens the initial alignment time through data acquisition at two different positions, thereby greatly improving the alignment accuracy of the main inertial navigation.

Description

Technical Field

[0001] The present invention relates to the technical field of inertial navigation, and particularly to a rapid initial alignment assistance device and its working method. Background Art

[0002] Currently, for inertial navigation devices, after power-on, initial alignment needs to be completed first to provide attitude angles (pitch angle, roll angle, heading angle) and an initial attitude matrix for the carrier. Initial alignment is a relatively important link in the inertial navigation system and is closely related to the subsequent inertial navigation accuracy. Generally, it is divided into two stages: rough alignment and fine alignment. The entire alignment process takes about 10 - 15 minutes. In rough alignment, analytical self-alignment is used. The vector matrix is solved by using the angular velocity components measured by the gyroscope and the specific force components measured by the accelerometer. The method is simple, but since the outputs of the gyroscope and accelerometer contain constant zero-bias terms, it will bring errors to the initial alignment. In the fine alignment stage, the velocity error is used as the observable quantity, and Kalman filtering is used for error estimation. However, the time is relatively long, and some state variables are unobservable or have weak observability, which affects the alignment accuracy.

[0003] In the prior art, generally, there are two methods to quickly improve the inertial navigation initial alignment accuracy, namely external heading alignment or two-position alignment. External heading alignment uses the GNSS dual-antenna heading angle or the externally loaded heading angle for rapid alignment. However, there is an installation error angle between the external heading angle and the inertial navigation body coordinate system, and calibration is relatively difficult. Two-position alignment requires the inertial navigation device to be rotated 90° or 180° through a rotating mechanism during the alignment process to improve the observability of the system, thereby improving the alignment accuracy. However, in the actual environment, the inertial navigation device is generally fixedly connected to the carrier, and this method is generally difficult to implement.

[0004] Therefore, in view of the problem that the existing inertial navigation devices are difficult to achieve rapid alignment and accuracy improvement, a rapid initial alignment assistance device and its working method can be designed. Summary of the Invention

[0005] In order to overcome the problem that the existing inertial navigation devices are difficult to achieve rapid alignment and accuracy improvement.

[0006] The technical solution of the present invention is: a rapid initial alignment assistance device, including an auxiliary device main body, a circuit board, a dual-axis MEMS accelerometer, a dual-axis fiber optic gyroscope, a connector, and a card slot. The bottom end of the inner wall of the auxiliary device main body is fixedly installed with a circuit board, the upper end of the circuit board is fixedly installed with a dual-axis MEMS accelerometer, the upper end of the inner wall of the auxiliary device main body is fixedly installed with a dual-axis fiber optic gyroscope, the right end of the auxiliary device main body is fixedly connected with a connector, the lower end of the auxiliary device main body is fixedly connected with a card slot, and the right side of the card slot is adhesively connected with a main inertial navigation.

[0007] Preferably, the main inertial navigation is electrically connected to the connector.

[0008] Preferably, the sensitive axes of the dual-axis fiber optic gyroscope are aligned with the horizontal X and Y axes.

[0009] A working method for the rapid initial alignment auxiliary device, including the rapid initial alignment auxiliary device as described above, the steps are as follows: First step, the main body 1 of the auxiliary device is closely attached to the edge of the main inertial navigation 7 through the card slot 6, the axes are completely parallel, and it is connected to the connector 5 through the connecting wire on the main inertial navigation 7. After the connection is completed, the main body 1 of the auxiliary device is powered on for self-check; Second step, the auxiliary device collects the original IMU data. First, collect data for 30 s at the first position, then manually rotate the main body 1 of the auxiliary device by 180°, and then collect data for 30 s at the second position to obtain the measurement values; Third step, after the data collection at the second position is completed, calculate the pitch angle , roll angle , and heading angle of the main inertial navigation according to Formula 1 and Formula 2, as well as the three components of the earth's angular velocity of rotation in the X, Y, and Z axis directions , , . After the calculation is completed, the calculation results of these six components are transmitted to the main inertial navigation 7 through the connector 5; Fourth step, the main inertial navigation 7 is powered on for self-check; Fifth step, the main inertial navigation 7 starts to collect the original IMU data and continuously judges whether it has received the calculation results of the auxiliary device. After receiving it, calculate the attitude matrix according to Formula 3 to complete the initial alignment process; Sixth step, correct the inertial navigation zero bias parameters according to Formula 4 and Formula 5 , , , , . If the calculation results of the auxiliary device are not received, the analytical rough alignment and Kalman filter fine alignment are carried out according to the conventional process. After the alignment is completed, enter the navigation calculation and integrated navigation process. If the calculation results of the auxiliary device are received, the main inertial navigation 7 completes the rapid initial alignment and error compensation.

[0010] Preferably, the calculation formulas for the measurement values of the dual-axis fiber optic gyroscope 4 and the dual-axis MEMS accelerometer 3 in the auxiliary device at the first position and the second position in the second step are as follows:

[0011] First position: , second position: , where , are the measurement values of the two gyroscopes on the X and Y axes at the first position of the auxiliary device, , are the measurement values of the two gyroscopes on the X and Y axes at the second position, , are the zero bias values of the gyroscopes on the X and Y axes of the auxiliary device. , are the components of the angular velocity of the Earth's rotation on the X and Y axes, , , , are the measurement noises of the gyroscopes of the auxiliary devices, , , , are the measurement noises of the accelerometers of the auxiliary devices, is the pitch angle of the main inertial navigation, is the roll angle of the main inertial navigation, g is the acceleration due to gravity, generally taken as 9.8 m / s 2 .

[0012] Preferably, the formula one in the third step is as follows: .

[0013] Preferably, the formula two in the third step is as follows: .

[0014] Preferably, the formula three in the fifth step is as follows: .

[0015] Preferably, while calculating the attitude matrix of the main inertial navigation 7 in the fifth step, the main inertial navigation 7 can quickly separate the horizontal zero bias components , of the accelerometer and the zero bias components , , of the gyroscope according to the pitch angle, roll angle, and the components of the angular velocity of the Earth's rotation in the X and Y axis directions transmitted by the auxiliary devices.

[0016] Take the average values of the measurement values of the gyroscopes and accelerometers of the main inertial navigation over a period of time , , , Their mathematical model is: , where , are the measurement noises of the gyroscopes of the main inertial navigation, , are the measurement noises of the accelerometers of the main inertial navigation.

[0017] Preferably, the formula four and formula five in the sixth step are as follows: .

[0018] Advantages of the present invention:

[0019] Without changing the installation method and structure of the original inertial navigation device, the external auxiliary alignment device of this rapid initial alignment auxiliary device enables extremely convenient disassembly and assembly processes, without specific installation requirements, achieving the flexibility of plug-and-play, greatly enhancing the operation convenience. Secondly, by collecting data at two different positions, the auxiliary device can quickly calculate the attitude angle of the main inertial navigation and the earth's rotation angular velocity, significantly shortening the initial alignment time, and effectively estimating and compensating the zero bias of the gyroscope and the zero bias error of the accelerometer, thereby greatly improving the alignment accuracy of the main inertial navigation, solving the problems of error influence and long alignment time in traditional alignment methods, and having extremely high practical value and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of the present invention; Figure 2 Schematic diagram of the connection relationship between the auxiliary device at the first position and the main inertial navigation of the present invention; Figure 3 Schematic diagram of the connection relationship between the auxiliary device at the second position and the main inertial navigation of the present invention; Figure 4 Flowchart of the operation of the present invention.

[0021] Description of reference numerals: 1. Main body of the auxiliary device; 2. Circuit board; 3. Biaxial MEMS accelerometer; 4. Biaxial fiber optic gyroscope; 5. Connector; 6. Card slot; 7. Main inertial navigation. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present invention will be further described below with reference to the drawings and embodiments.

[0023] Please refer to Figures 1-4 , the present invention provides an embodiment: a rapid initial alignment auxiliary device, including a main body 1 of the auxiliary device, a circuit board 2, a biaxial MEMS accelerometer 3, a biaxial fiber optic gyroscope 4, a connector 5 and a card slot 6. The bottom end of the inner wall of the main body 1 of the auxiliary device is fixedly installed with a circuit board 2, the upper end of the circuit board 2 is fixedly installed with a biaxial MEMS accelerometer 3, the upper end of the inner wall of the main body 1 of the auxiliary device is fixedly installed with a biaxial fiber optic gyroscope 4, the right end of the main body 1 of the auxiliary device is fixedly connected with a connector 5, the lower end of the main body 1 of the auxiliary device is fixedly connected with a card slot 6, the right side of the card slot 6 is adhesively connected with a main inertial navigation 7. The circuit board 2 is used for data acquisition and processing. The design of the card slot 6 below the main body 1 of the auxiliary device is to fit with the edge of the main inertial navigation 7, so that the auxiliary device and the main inertial navigation device are axially aligned. The main inertial navigation 7 is electrically connected with the connector 5, and through the connector 5, the auxiliary device can be connected with the main inertial navigation device. The sensitive axes of the biaxial fiber optic gyroscope 4 are consistent with the horizontal X and Y axis directions, and are used to measure the angular velocity in the horizontal direction. The biaxial accelerometer measures the specific force components in the horizontal direction.

[0024] The working method of the rapid initial alignment auxiliary device is as follows:

[0025] First step: The auxiliary device body is closely attached to the edge of the main inertial navigation through the card slot, with the axes being completely parallel. It is connected to the connector through the connecting wire on the main inertial navigation. After the connection is completed, power on the auxiliary device body for self-check; Second step: The auxiliary device collects the original IMU data. First, collect data for 30 s at the first position, then manually rotate the auxiliary device body by 180°, and then collect data for 30 s at the second position to obtain the measured values; Third step: After completing the data collection at the second position, calculate the pitch angle of the main inertial navigation according to Formula 1 and Formula 2 , roll angle , and heading angle , and the three components of the earth's angular velocity of rotation in the X, Y, and Z axis directions , , . After the calculation is completed, transmit the calculation results of these six components to the main inertial navigation through the connector; Fourth step: Power on the main inertial navigation for self-check; Fifth step: The main inertial navigation starts to collect the original IMU data and continuously judges whether it has received the calculation results of the auxiliary device. After receiving them, calculate the attitude matrix according to Formula 3 to complete the initial alignment process; Sixth step: Correct the inertial navigation zero bias parameters according to Formula 4 and Formula 5 , , , , . If it has not received the calculation results of the auxiliary device, perform analytical rough alignment and Kalman filter fine alignment according to the conventional process. After the alignment is completed, enter the navigation calculation and integrated navigation process. If it has received the calculation results of the auxiliary device, the main inertial navigation completes the rapid initial alignment and error compensation

[0026] The calculation formulas for the measured values of the dual-axis fiber optic gyroscope and the dual-axis MEMS accelerometer in the auxiliary device at the first position and the second position in the second step are as follows:

[0027] First position: , second position: , where , are the measured values of the two gyroscopes on the X and Y axes at the first position of the auxiliary device, , are the measured values of the two gyroscopes on the X and Y axes at the second position, , are the zero bias values of the gyroscopes on the X and Y axes of the auxiliary device, , are the components of the earth's angular velocity of rotation on the X and Y axes, , , , are the measurement noises of the gyroscopes of the auxiliary device, ​​​​​​​, , , is the measurement noise of the accelerometer of the auxiliary device, is the pitch angle of the main inertial navigation, is the roll angle of the main inertial navigation, and g is the acceleration due to gravity, generally taken as 9.8 m / s 2 .

[0028] The first formula in the third step is as follows: , and the second formula in the third step is as follows: , and the third formula in the fifth step is as follows: .

[0029] While calculating the attitude matrix of the main inertial navigation in the fifth step, the main inertial navigation can quickly separate the horizontal zero bias component , of the accelerometer and the zero bias component , , of the gyroscope according to the pitch angle, roll angle, and the components of the earth's angular velocity in the X and Y axis directions transmitted by the auxiliary device.

[0030] Take the average values of the measured values of the gyroscope and accelerometer of the main inertial navigation over a period of time , , , , and its mathematical model is: , where , is the measurement noise of the gyroscope of the main inertial navigation, , is the measurement noise of the accelerometer of the main inertial navigation.

[0031] The fourth and fifth formulas in the sixth step are as follows: .

[0032] Embodiment

[0033] Since the main inertial navigation and the auxiliary device are closely attached through the card slot at the two positions and are completely parallel axially, it is considered that the pitch angle, roll angle, and heading angle of the main inertial navigation and the auxiliary device are the same, and the components of the earth's angular velocity on the body coordinate systems of the two devices are also the same.

[0034] The measured values of the gyroscope and accelerometer at the two positions of the auxiliary device are respectively:

[0035] First position: , second position: . Among them, , the measured values of the two gyroscopes on the X and Y axes at the first position of the auxiliary device, , are the measured values of two gyroscopes on the second position's X and Y axes, , are the zero bias values of the X and Y axis gyroscopes of the auxiliary device. , are the components of the earth's angular velocity of rotation on the X and Y axes. , , , are the measurement noises of the gyroscopes of the auxiliary device, , , are the measurement noises of the accelerometers of the auxiliary device. is the pitch angle of the main inertial navigation system, is the roll angle of the main inertial navigation system. g is the acceleration due to gravity, generally taken as 9.8 m / s 2 .

[0036] Since the two positions are 180° apart, the signs of the components of the earth's angular velocity of rotation on the body coordinate system and the horizontal attitude angle components (pitch angle and roll angle) are opposite at the two different positions, while the gyroscope zero bias and accelerometer zero bias are constant components with unchanged signs. Thus, based on the measured values at the two positions, the pitch angle , roll angle , heading angle of the main inertial navigation system, as well as the three components , , of the earth's rotation component on the b coordinate system of the inertial navigation body can be calculated. The calculation formulas are as follows: Transfer the pitch angle, roll angle, and heading angle measured by the auxiliary device to the main inertial navigation system, and calculate the attitude matrix of the main inertial navigation system according to the following formula That is, the initial alignment of the main inertial navigation system is completed, .

[0037] At the same time, based on the pitch angle, roll angle transferred by the auxiliary device, and the components of the earth's angular velocity of rotation in the X and Y axis directions, the main inertial navigation system can quickly separate the horizontal zero bias components , of the accelerometer and the zero bias components , , of the gyroscope.

[0038] Take the average values , , , of the measured values of the gyroscopes and accelerometers of the main inertial navigation system over a period of time. Its mathematical model is: , where , is the measurement noise of the main inertial navigation gyroscope, , is the measurement noise of the main inertial navigation accelerometer. Thus, we obtain: .

[0039] According to the above calculations, the auxiliary device not only quickly provides the pitch angle, roll angle, and heading angle for the main inertial navigation, calculates the initial attitude matrix, and achieves rapid initial alignment, but also compensates for the gyroscope zero bias and accelerometer zero bias that cannot be accurately estimated during fine alignment. After the main inertial navigation achieves rapid initial alignment, there is no need to perform the fine alignment process again, which not only improves the alignment accuracy but also greatly shortens the alignment time.

[0040] Through the above steps, the role of the auxiliary device is to quickly separate the attitude angle and the earth's angular velocity component of the main inertial navigation through the two-position angular velocity measurement and specific force measurement of the auxiliary device. After transmitting them to the main inertial navigation, a relatively accurate initial attitude matrix can be directly obtained based on the attitude angle. Then, based on the gyroscope measurement value and accelerometer measurement value of the main inertial navigation, the gyroscope zero bias and accelerometer zero bias are separated, and a relatively accurate initial alignment result can be quickly obtained, so as to solve the problem that it is difficult for existing inertial navigation devices to achieve rapid alignment and accuracy improvement.

[0041] Experimental example

[0042] Two sets of inertial navigations are used for experimental verification. One set is a high-precision fiber optic inertial navigation as the main inertial navigation, and the other set is a miniaturized low-precision fiber optic inertial navigation as the auxiliary device. After power-on, the auxiliary device collects data according to two positions and calculates the pitch angle, roll angle, and heading angle of the main inertial navigation, as well as the earth's angular velocity component. After transmitting the results to the main inertial navigation, the main inertial navigation calculates the attitude matrix in real time and corrects the gyroscope zero bias and accelerometer zero bias.

[0043] The test results show that compared with the self-alignment method of the main inertial navigation, after using the auxiliary device, the initial alignment time of the main inertial navigation is greatly shortened, and the accuracy is also significantly improved. The results are compared as follows:

[0044] Serial number Option Self-alignment method Using auxiliary equipment Lifting range 1 Alignment time 10 minutes 1.5 minutes ↓85% 2 Pitch angle accuracy 20 arcseconds 1 arcsecond ↑95% 3 Roll angle accuracy 20 arcseconds 1 arcsecond ↑95% 4 Heading angle accuracy 3 arcminutes 0.6 arcminutes ↑80%

[0045] The alignment time is reduced by 85%, the horizontal attitude angle accuracy is improved by 95%, and the heading angle accuracy is improved by 80%. It can be seen that using the alignment auxiliary device method greatly shortens the initial alignment time and improves the initial alignment accuracy.

[0046] The above has described the embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the gist of the present invention.

Claims

1. A rapid initial alignment auxiliary device, comprising an auxiliary device body (1); characterized in that: The auxiliary device also comprises a circuit board (2), a dual-axis MEMS accelerometer (3), a dual-axis fiber optic gyroscope (4), a connector (5) and a card slot (6); the circuit board (2) is fixedly mounted on the bottom end of the inner wall of the auxiliary device body (1); the dual-axis MEMS accelerometer (3) is fixedly mounted on the upper end of the circuit board (2); the dual-axis fiber optic gyroscope (4) is fixedly mounted on the upper end of the inner wall of the auxiliary device body (1); the connector (5) is fixedly connected to the right end of the auxiliary device body (1); and the card slot is fixedly connected to the lower end of the auxiliary device body (1). (6), the main inertial navigation system (7) is fitted and connected to the right side of the card slot (6); the auxiliary device body (1) is tightly fitted with the edge of the main inertial navigation system (7) through the card slot (6), the axes are completely parallel, and the auxiliary device body (1) is connected to the connector (5) through the connecting line on the main inertial navigation system (7), and after the connection is completed, the auxiliary device body (7) is powered on for self-test; the auxiliary device collects IMU raw data, first collects data for 30 seconds at the first position, then manually rotates the auxiliary device body (1) 180 degrees, and then collects data for 30 seconds at the second position to obtain the measurement value.

2. The rapid initial alignment auxiliary device according to claim 1, characterized in that: The main inertial navigation system (7) is electrically connected to the connector (5).

3. The rapid initial alignment auxiliary device according to claim 1, characterized in that: The sensitive axes of the dual-axis fiber optic gyroscope (4) are consistent with the directions of the horizontal X and Y axes.

4. The working method of the rapid initial alignment auxiliary device according to any one of claims 1 to 3, characterized in that: The working method comprises the following steps: first, the auxiliary device body (1) is tightly fitted with the edge of the main inertial navigation system (7) through the card slot (6), the axes are completely parallel, and the auxiliary device body (1) is connected to the connector (5) through the connecting wire on the main inertial navigation system (7). After the connection is completed, the auxiliary device body (1) is powered on for self-test; second, the auxiliary device collects IMU raw data, first collects data for 30 seconds at the first position, then manually rotates the auxiliary device body (1) by 180 degrees, and then collects data for 30 seconds at the second position to obtain a measurement value; The third step is to calculate the pitch angle of the main inertial navigation after completing the second position data collection. , Roll Angle , and the heading angle , and the three components of the Earth's rotational velocity in the X, Y, and Z directions , , After the calculation is completed, the solution results of the six components are transmitted to the main inertial navigation system (7) through the connector (5); Step 4: Power on the main inertial navigation system (7) for self-test; In the fifth step, the main inertial navigation (7) starts to collect IMU raw data and determines in real time whether it has received the solution results of the auxiliary equipment. After receiving them, it calculates the attitude matrix , complete the initial alignment process; Step 6: Correct the inertial navigation bias parameters according to formula 4 and formula 5 , , , , If the calculation result of the auxiliary equipment is not received, the analytical coarse alignment and Kalman filter fine alignment are performed according to the conventional process. After the alignment is completed, the navigation solution and combined navigation process are entered. If the calculation result of the auxiliary equipment is received, the main inertial navigation (7) completes the fast initial alignment and error compensation.

5. The working method of the rapid initial alignment auxiliary device according to claim 4, characterized in that: In the second step, the calculation formula of the measured values ​​of the dual-axis fiber optic gyroscope (4) and the dual-axis MEMS accelerometer (3) in the auxiliary equipment at the first position and the second position is as follows: First Position: , second position: ,in, , are the measurements of the two gyroscopes on the X and Y axes of the auxiliary device at the first position, , are the measurement values ​​of the two gyroscopes on the X and Y axes at the second position, , is the zero bias value of the auxiliary equipment X and Y axis gyroscope, , is the component of the Earth's rotation angular velocity on the X and Y axes, , , , To assist the measurement noise of the device gyroscope, , , , is the measurement noise of the auxiliary device accelerometer, is the pitch angle of the main inertial navigation, is the roll angle of the main inertial navigation system, g is the acceleration of gravity, which is generally taken as 9.8m / s 2 .

6. The working method of the rapid initial alignment auxiliary device according to claim 4, characterized in that: In the third step, after completing the second position data acquisition, the pitch angle of the main inertial navigation is calculated according to formula 1 and formula 2. , Roll Angle , and the heading angle , and the three components of the Earth's rotational velocity in the X, Y, and Z directions , , , where formula 1 is as follows: .

7. The working method of the rapid initial alignment auxiliary device according to claim 4, characterized in that: In the third step, after completing the second position data acquisition, the pitch angle of the main inertial navigation is calculated according to formula 1 and formula 2. , Roll Angle , and the heading angle , and the three components of the Earth's rotational velocity in the X, Y, and Z directions , , , where formula 2 is as follows: .

8. The working method of the rapid initial alignment auxiliary device according to claim 4, characterized in that: In the fifth step, the main inertial navigation system (7) starts to collect IMU raw data and determines in real time whether the solution result of the auxiliary device has been received. After receiving it, the attitude matrix is ​​calculated according to formula 3 , complete the initial alignment process, where Formula 3 is as follows: .

9. The working method of the rapid initial alignment auxiliary device according to claim 4, characterized in that: In the fifth step, the attitude matrix of the main inertial navigation (7) is calculated At the same time, the main inertial navigation (7) can quickly separate the horizontal zero bias component of the accelerometer according to the pitch angle, roll angle, and the earth's rotation angular velocity components in the X and Y axis directions transmitted by the auxiliary equipment. , and gyro bias component , , , take the average value of the gyro and accelerometer measurements of the main inertial navigation for a period of time , , , , its mathematical model is: ,in , The main inertial navigation gyro measures noise, , Measure noise for the primary inertial navigation accelerometer.

10. The working method of the rapid initial alignment auxiliary device according to claim 4, characterized in that: Formula 4 and Formula 5 in step 6 are as follows: .

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