Rapid initial alignment auxiliary equipment and working method thereof

Abstract

The invention relates to the technical field of inertial navigation, in particular to rapid initial alignment auxiliary equipment and a working method.The rapid initial alignment auxiliary equipment comprises an auxiliary equipment body, a circuit board, a double-axis MEMS accelerometer, a double-axis optical fiber gyroscope, a connector and a clamping groove, the circuit board is fixedly installed at the bottom end of the inner wall of the auxiliary equipment body, and the circuit board is fixedly installed at the bottom end of the inner wall of the auxiliary equipment body; the upper end of the circuit board is fixedly provided with a double-shaft MEMS accelerometer, the upper end of the inner wall of the auxiliary equipment main body is fixedly provided with a double-shaft optical fiber gyroscope, the right end of the auxiliary equipment main body is fixedly connected with a connector, the lower end of the auxiliary equipment main body is fixedly connected with a clamping groove, and the right side of the clamping groove is connected with a main inertial navigation in an attached mode; on the premise that the installation mode and structure of original inertial navigation equipment are not changed, the operation convenience is greatly improved through the design of the external auxiliary alignment equipment, and then the initial alignment time is remarkably shortened through data acquisition at two different positions by the auxiliary equipment, so that the alignment precision of the main inertial navigation equipment is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of inertial navigation technology, and in particular to a rapid initial alignment auxiliary device and a working method thereof. Background Art

[0002] At present, for inertial navigation equipment, the initial alignment must be completed first after power-on to provide the carrier with attitude angles (pitch angle, roll angle, heading angle) and initial attitude matrix. Initial alignment is a relatively important part of the inertial navigation system, which is closely related to the subsequent inertial navigation accuracy. It is generally divided into two stages: coarse alignment and fine alignment. The entire alignment process takes about 10 to 15 minutes. Coarse alignment uses analytical self-alignment, using the angular velocity component measured by the gyroscope and the specific force component measured by the accelerometer to establish a vector matrix solution. The method is simple, but because the gyroscope and accelerometer outputs contain constant zero bias terms, it will cause errors in the initial alignment; the fine alignment stage uses velocity error as the observed quantity, and uses Kalman filtering for error estimation, but the time is relatively long, and some state variables are not observable or the observability is weak, which affects the alignment accuracy.

[0003] In the prior art, there are generally two methods to quickly improve the initial alignment accuracy of the inertial navigation system, namely external heading alignment or two-position alignment. External heading alignment uses the GNSS dual-antenna heading angle or the externally bound heading angle for rapid alignment, but there is an installation error angle between the external heading angle and the inertial navigation body coordinate system, which is difficult to correct; 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 and thus improve the alignment accuracy, but in actual environments, the inertial navigation device is generally fixed to the carrier, and this method is generally difficult to implement.

[0004] Therefore, in order to solve the problem that the existing inertial navigation equipment is difficult to achieve rapid alignment and accuracy improvement, a rapid initial alignment auxiliary equipment and a working method thereof can be designed. Summary of the invention

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

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

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

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

[0009] The working method of the rapid initial alignment auxiliary device includes the rapid initial alignment auxiliary device as described above, and the steps are as follows: in the first step, the auxiliary device body 1 is tightly fitted with the edge of the main inertial navigation 7 through the card slot 6, the axis is completely parallel, and the auxiliary device body 1 is connected to the connector 5 through the connecting line on the main inertial navigation 7. After the connection is completed, the auxiliary device body 1 is powered on for self-test; in the second step, the auxiliary device collects IMU raw data, first collects 30 seconds of data at the first position, then manually rotates the auxiliary device body 1 180°, and then collects 30 seconds of data at the second position to obtain the measurement value; in the third step, after completing the data collection at the second position, the pitch angle of the main inertial navigation is calculated according to Formula 1 and Formula 2 , Roll Angle , and 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; the fourth step is that the main inertial navigation system 7 is powered on for self-test; the fifth step is that the main inertial navigation system 7 starts to collect the IMU raw data and determines in real time whether the solution results of the auxiliary equipment are received. After receiving them, the attitude matrix is ​​calculated according to formula 3 , complete the initial alignment process; Step 6, correct the inertial navigation zero 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.

[0010] Preferably, the measurement value calculation formula 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 in the second step 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 due to gravity, and is generally taken as 9.8 m / s 2 .

[0011] Preferably, formula 1 in the third step is as follows: .

[0012] Preferably, formula 2 in the third step is as follows: .

[0013] Preferably, formula 3 in step 5 is as follows: .

[0014] As a preferred method, the attitude matrix of the main inertial navigation system 7 is calculated in the fifth step. At the same time, the main inertial navigation system 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 , , .

[0015] Take the average of the gyro and accelerometer measurements of the main inertial navigation system over a period of time , , , Its mathematical model is: , in , The main inertial navigation gyro measures noise, , Measure noise for the primary inertial navigation accelerometer.

[0016] Preferably, formula 4 and formula 5 in step 6 are as follows: .

[0017] Beneficial effects of the present invention: Without changing the installation method and structure of the original inertial navigation equipment, the external auxiliary alignment equipment design of the rapid initial alignment auxiliary equipment makes the disassembly and assembly process extremely convenient, without the need for specific installation requirements, and realizes the flexibility of plug-and-play, which greatly improves the convenience of operation. Secondly, the auxiliary equipment can quickly calculate the attitude angle of the main inertial navigation and the angular velocity of the earth's rotation by collecting data at two different positions, which significantly shortens the initial alignment time, and effectively estimates and compensates for the gyroscope zero bias and accelerometer zero bias errors, 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 has extremely high practical value and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a schematic diagram of the connection relationship between the first position auxiliary device and the main inertial navigation system of the present invention; Figure 3 It is a schematic diagram of the connection relationship between the second position auxiliary device and the main inertial navigation system of the present invention; Figure 4 It is the work flow chart of the present invention.

[0019] Explanation of the accompanying drawings: 1. Auxiliary equipment body; 2. Circuit board; 3. Dual-axis MEMS accelerometer; 4. Dual-axis fiber optic gyroscope; 5. Connector; 6. Card slot; 7. Main inertial navigation. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0021] See also Figure 1-Figure 4 The present invention provides an embodiment: a rapid initial alignment auxiliary device, comprising an auxiliary device body 1, 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 installed at the bottom end of the inner wall of the auxiliary device body 1, the dual-axis MEMS accelerometer 3 is fixedly installed at the upper end of the circuit board 2, the dual-axis fiber optic gyroscope 4 is fixedly installed at 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, the card slot 6 is fixedly connected to the lower end of the auxiliary device body 1, and the right side of the card slot 6 is bonded and connected with a main inertial navigation 7, the circuit board 2 is used for data acquisition and processing, the card slot 6 below the auxiliary device body 1 is designed to be bonded with the edge of the main inertial navigation 7, so that the auxiliary device is axially aligned with the main inertial navigation device, the main inertial navigation 7 is electrically connected to the connector 5, and the auxiliary device can be connected to the main inertial navigation device through the connector 5, the sensitive axis of the dual-axis fiber optic gyroscope 4 is consistent with the horizontal X and Y axis directions, and is used to measure the horizontal angular velocity, and the dual-axis accelerometer measures the specific force component in the horizontal direction.

[0022] The working method of the rapid initial alignment aid is as follows: In the first step, the auxiliary device body is tightly fitted with the edge of the main inertial navigation through the card slot, with the axis completely parallel, and connected to the connector through the connecting line on the main inertial navigation. After the connection is completed, the auxiliary device body is powered on for self-test; in the second step, the auxiliary device collects IMU raw data, first collects 30s of data at the first position, then manually rotates the auxiliary device body 180°, and then collects 30s of data at the second position to obtain the measurement value; in the third step, after completing the data collection at the second position, the pitch angle of the main inertial navigation is calculated according to formulas 1 and 2 , 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 these six components are transmitted to the main inertial navigation through the connector; the fourth step is the main inertial navigation power-on self-test; the fifth step is that the main inertial navigation starts to collect IMU raw data and judges in real time whether the solution results of the auxiliary equipment are received. After receiving them, the attitude matrix is ​​calculated according to formula three , complete the initial alignment process; Step 6, correct the inertial navigation zero 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 completes the rapid initial alignment and error compensation.

[0023] In the second step, the calculation formula for the measurement values ​​of the dual-axis fiber optic gyroscope and the dual-axis MEMS accelerometer 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, , Zero bias value of auxiliary equipment X and Y axis gyroscope, , The components of the Earth's rotational 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 .

[0024] The formula in step 3 is as follows: , Formula 2 in the third step is as follows: , Formula 3 in the fifth step is as follows: .

[0025] In the fifth step, the attitude matrix of the main inertial navigation is calculated At the same time, the main inertial navigation can quickly separate the horizontal zero bias component of the accelerometer based on 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 , , .

[0026] Take the average of the gyro and accelerometer measurements of the main inertial navigation system over a period of time , , , , its mathematical model is: , in , The main inertial navigation gyro measures noise, , Measure noise for the primary inertial navigation accelerometer.

[0027] Formula 4 and Formula 5 in step 6 are as follows: .

[0028] Example Since the main inertial navigation and the auxiliary equipment at the two positions are tightly fitted through the slots and the axes are completely parallel, it is believed that the pitch angle, roll angle and heading angle of the main inertial navigation and the auxiliary equipment are consistent, and the components of the earth's rotation angular velocity in the body coordinate systems of the two devices are also consistent.

[0029] The two position gyro and accelerometer measurements of the auxiliary device are: First Position: , second position: .in, , 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, , 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, , , Measurement noise of auxiliary equipment accelerometers. is the pitch angle of the main inertial navigation, The roll angle of the main inertial navigation. g is the acceleration of gravity, which is generally taken as 9.8m / s 2 .

[0030] Since the two positions differ by 180°, the components of the Earth's rotational angular velocity in the body coordinate system and the horizontal attitude angle components (pitch angle and roll angle) have opposite signs at the two different positions, while the gyroscope bias and accelerometer bias are constant components with unchanged signs. Therefore, the pitch angle of the main inertial navigation can be calculated based on the measured values ​​at the two positions. , Roll Angle , heading angle , and the three components of the earth's rotation component in the inertial navigation body coordinate system b , , The calculation formula is as follows: The pitch angle, roll angle and heading angle measured by the auxiliary equipment are transmitted to the main inertial navigation system, and the attitude matrix of the main inertial navigation system is calculated according to the following formula: That is to complete the initial alignment of the main inertial navigation. .

[0031] At the same time, the main inertial navigation can quickly separate the horizontal zero bias component of the accelerometer based on 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 , , .

[0032] Take the average of the gyro and accelerometer measurements of the main inertial navigation system over a period of time , , , , its mathematical model is: , in , The main inertial navigation gyro measures noise, , The noise is measured for the main inertial navigation accelerometer. Thus, we get: .

[0033] According to the above calculations, the auxiliary equipment not only quickly provides the pitch angle, roll angle and heading angle for the main inertial navigation, calculates the initial attitude matrix and realizes fast initial alignment, but also compensates for the gyroscope zero bias and accelerometer zero bias that cannot be accurately estimated by precise alignment. After the main inertial navigation realizes fast initial alignment, there is no need to perform precise alignment process, which not only improves the alignment accuracy, but also greatly shortens the alignment time.

[0034] Through the above steps, the role of the auxiliary equipment is to quickly separate the attitude angle of the main inertial navigation and the angular velocity component of the earth's rotation through the two-position angular velocity measurement and specific force measurement of the auxiliary equipment. After transmitting them to the main inertial navigation, a relatively accurate initial attitude matrix can be directly obtained according to the attitude angle, and then the gyroscope zero bias and the accelerometer zero bias are separated according to the gyroscope measurement value and accelerometer measurement value of the main inertial navigation. Then, a relatively accurate initial alignment result can be quickly obtained to solve the problem that the existing inertial navigation equipment is difficult to achieve rapid alignment and accuracy improvement.

[0035] Experimental example Two sets of inertial navigation systems were used for test verification. One set is a high-precision fiber-optic inertial navigation system, which is used as the main inertial navigation system, and the other set is a miniaturized low-precision fiber-optic inertial navigation system, which is used as an auxiliary device. After power-on, the auxiliary device collects data from two positions and calculates the pitch angle, roll angle and heading angle of the main inertial navigation system, as well as the angular velocity component of the earth's rotation. After passing the results to the main inertial navigation system, the main inertial navigation system calculates the attitude matrix in real time and corrects the gyroscope bias and accelerometer bias.

[0036] The test results show that compared with the main inertial navigation self-alignment method, the initial alignment time of the main inertial navigation is greatly shortened and the accuracy is significantly improved after the auxiliary equipment is used. The results are compared as follows: Serial number Options Self-alignment method Use auxiliary equipment Improvement 1 Align the time 10 minutes 1.5 minutes ↓85% 2 Pitch angle accuracy 20 arc seconds 1 arc second ↑95% 3 Roll angle accuracy 20 arc seconds 1 arc second ↑95% 4 Heading angle accuracy 3 arc minutes 0.6 arc minute ↑80% The alignment time was reduced by 85%, the horizontal attitude angle accuracy was improved by 95%, and the heading angle accuracy was improved by 80%. It can be seen that the use of alignment auxiliary equipment greatly shortened the initial alignment time and improved the initial alignment accuracy.

[0037] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of those skilled in the art without departing from the spirit 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); the card slot (6) is fixedly connected to the lower end of the auxiliary device body (1); and the main inertial navigation system (7) is bonded to the right side of the card slot (6).

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 claim 1, characterized in that: The method comprises the rapid initial alignment auxiliary device according to any one of claims 1 to 3, wherein the steps are as follows: In the first step, the auxiliary device body (1) is tightly fitted with the edge of the main inertial navigation system (7) through the card slot (6), with the axes being completely parallel, and 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; In the second step, 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; The third step is to calculate the pitch angle of the main inertial navigation system according to formula 1 and formula 2 after completing the second position data collection. , roll angle , and the heading angle , and the three components of the Earth's rotational angular 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 according to formula 3 , 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 integrated 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, , The measurement values ​​of the two gyroscopes on the X and Y axes at the second location, , 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: The formula in step 3 is as follows: 。 7. The working method of the rapid initial alignment auxiliary device according to claim 4, characterized in that: Formula 2 in the third step is as follows: 。 8. The working method of the rapid initial alignment auxiliary device according to claim 4, characterized in that: Formula 3 in step 5 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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