Dynamic transfer alignment method suitable for attitude overturning

Abstract

The invention discloses a dynamic transfer alignment method suitable for attitude turnover, which comprises the following steps: receiving turnover state, working state of main inertial navigation, direction attitude of the main inertial navigation and speed information of the main inertial navigation after a sub inertial navigation is electrified, executing a transfer alignment process when the main inertial navigation finishes initial alignment and the working state is normal, otherwise, enabling the sub inertial navigation to be in a preparation state; compared with the prior art, the scheme can adapt to the influence of the overturning action of the sea-based sub inertial navigation on transfer alignment, and the zero offset of the gyroscope accelerometer is estimated by fully utilizing the overturning action, so that the alignment precision is improved.

Description

Technical Field

[0001] This invention belongs to the field of inertial navigation technology and relates to a dynamic transfer alignment method applicable to attitude flipping between master and slave inertial navigation systems. Background Technology

[0002] In main / sub-platform application scenarios, the inertial navigation equipment in the sub-platform typically completes the initialization of navigation information quickly by transmitting alignment, providing initial conditions for the platform's subsequent navigation, positioning, and attitude measurement.

[0003] In some application scenarios, the sub-platform and the main platform rotate relative to each other, resulting in a non-rigid connection between the main and sub-inertial navigation systems and the error model no longer meeting the requirements of the small-angle error model, thus causing the traditional transfer alignment method to fail.

[0004] In application scenarios where attitude flipping occurs between the master and slave inertial navigation systems, traditional transfer alignment has the following problems:

[0005] (1) The sub-inertial navigation system has a large angle of flip relative to the main inertial navigation system, which does not meet the requirement that the attitude error observation in the traditional transfer alignment is a small angle;

[0006] (2) The Euler angle rotation sequence commonly used in inertial navigation is yaw-pitch-roll sequence. When the pitch angle is raised to 90 degrees, a spurious event occurs, that is, yaw and roll cannot be separated. Summary of the Invention

[0007] This application effectively avoids the aforementioned problems by rationally designing the IMU's internal coordinate system switching and fully utilizes both the pre-flip and post-flip states to estimate gyroscope and accelerometer zero bias, thereby improving alignment accuracy. To overcome the aforementioned deficiencies of the prior art, this invention provides...

[0008] The technical solution of this invention is as follows:

[0009] A dynamic transfer alignment method suitable for attitude flipping includes: after the sub-inertial navigation system is powered on, it receives the flipping state, the working state of the main inertial navigation system, the directional attitude of the main inertial navigation system and the speed information of the main inertial navigation system. When the main inertial navigation system has completed the initial alignment and is in normal working state, the transfer alignment process is executed; otherwise, the sub-inertial navigation system is in the ready state.

[0010] The steps for transferring alignment are as follows:

[0011] Step 1: In the horizontal state, switch to the horizontal state IMU coordinate system for transfer alignment estimation, gyroscope addition, and zero bias.

[0012] Step 2: Stop filtering during the flipping process and save the zero-bias estimation results;

[0013] Step 3: After flipping to the correct position, switch to the vertical IMU coordinate system, use the zero bias estimated in the horizontal state as the initial value, and restart the alignment transfer.

[0014] Step one specifically involves: with the sub-inertial navigation system in a horizontal state, rotating the coordinate system of the IMU's sensing axis inside the sub-inertial navigation system by 90 degrees around the lateral axis, switching it to a coordinate system roughly consistent with the sensing axis of the main inertial navigation system's IMU. The sub-inertial navigation system uses the heading and attitude of the main inertial navigation system as its initial heading and attitude values ​​after one binding, and uses the velocity and position of the main inertial navigation system after lever compensation as its initial velocity and position values. Then, a 15-dimensional state Kalman filter is established to estimate the zero bias of the gyroscope and accelerometer through "attitude + velocity" matching.

[0015] In a horizontal orientation, the coordinate system is rotated using the gyroscope and dial indicator measurements obtained from the sub-inertial navigation system calculations according to the following formula:

[0016]

[0017]

[0018]

[0019] Construct a state estimation model, and the system state vector X is as follows:

[0020]

[0021]

[0022] In the formula, These are attitude errors (i.e., heading angle error, pitch angle error, and roll angle error). This refers to the horizontal velocity error (i.e., the eastward velocity error and the northward velocity error). Accelerometer zero bias (including X / Y / Z three-axis accelerometer zero bias). Zero bias of the gyroscope (including zero bias of the X / Y / Z three-axis gyroscope). The installation error angle of the sub-inertial navigation system relative to the main inertial navigation system. Here is the state transition matrix. This is the system noise matrix.

[0023] The measurement equation is as follows:

[0024]

[0025] In the formula, For attitude measurement noise, Noise for speed measurement.

[0026] Step two specifically involves: after the sub-inertial navigation system detects the start of erection command, it judges the variance of the zero bias estimation of the gyro accelerometer. If convergence is achieved, the current estimation result is recorded; error estimation is stopped and the sub-inertial navigation system transfer alignment filter is reset; the coordinate system of the sensitive axis of the IMU inside the sub-inertial navigation system is restored to its original state (a coordinate system that is roughly consistent with the sensitive axis of the main inertial navigation IMU after flipping).

[0027] The zero bias of the gyroscope after restoring it to its original state can be calculated using the following formula.

[0028]

[0029]

[0030] In the formula, for The transpose of .

[0031] Step three specifically involves: after the sub-inertial navigation system detects that the system has been erected, the heading and attitude of the main inertial navigation system are used as the initial values ​​of the heading and attitude. The velocity and position of the main inertial navigation system after the arm compensation are used as the initial values ​​of velocity and position. The zero bias result of the gyroscope and accelerometer estimated by the horizontal state is used as the initial value. Then, a 15-dimensional state Kalman filter is established to estimate the zero bias of the gyroscope and accelerometer, as well as the attitude error and velocity error, through "attitude + velocity" matching.

[0032] The state equation and measurement equation used in step three are the same as those in step one.

[0033] The technical effects and advantages of this invention are as follows:

[0034] Compared with the prior art, the present invention can adapt to the influence of the flipping action of the sea-based inertial navigation system on the transmission alignment, and makes full use of the flipping action to estimate the zero bias of the gyroscope and the table to improve the alignment accuracy. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] like Figure 1The method shown is a dynamic transfer alignment method suitable for attitude flipping, which includes: after the sub-inertial navigation system is powered on, it receives the flipping state, the working state of the main inertial navigation system, the main inertial navigation system's heading attitude and the main inertial navigation system's speed information. When the main inertial navigation system has completed the initial alignment and is in normal working state, the transfer alignment process is executed; otherwise, the sub-inertial navigation system is in the preparation state.

[0039] The steps for transferring alignment are as follows:

[0040] Step 1: In the horizontal state, switch to the horizontal state IMU coordinate system for transfer alignment estimation, gyroscope addition, and zero bias.

[0041] Step 2: Stop filtering during the flipping process and save the zero-bias estimation results;

[0042] Step 3: After flipping to the correct position, switch to the vertical IMU coordinate system, use the zero bias estimated in the horizontal state as the initial value, and restart the alignment transfer.

[0043] Example 2

[0044] A dynamic transfer alignment method suitable for attitude flipping includes:

[0045] Step 1: With the sub-INS in a horizontal position, rotate the coordinate system of the IMU's sensing axis inside the sub-INS by 90 degrees around the lateral axis, switching it to a coordinate system roughly consistent with the sensing axis of the main INS IMU. The sub-INS uses the heading and attitude of the main INS as its initial heading and attitude values ​​after one binding, and uses the velocity and position of the main INS after lever compensation as its initial velocity and position values. Then, a 15-dimensional state Kalman filter is established to estimate the gyroscope and accelerometer bias through "attitude + velocity" matching.

[0046] In a horizontal orientation, the coordinate system is rotated using the gyroscope and dial indicator measurements obtained from the sub-inertial navigation system calculations according to the following formula:

[0047]

[0048]

[0049]

[0050] Construct a state estimation model, and the system state vector X is as follows:

[0051]

[0052]

[0053] In the formula, These are attitude errors (i.e., heading angle error, pitch angle error, and roll angle error). This refers to the horizontal velocity error (i.e., the eastward velocity error and the northward velocity error). Accelerometer zero bias (including X / Y / Z three-axis accelerometer zero bias). Zero bias of the gyroscope (including zero bias of the X / Y / Z three-axis gyroscope). The installation error angle of the sub-inertial navigation system relative to the main inertial navigation system. Here is the state transition matrix. This is the system noise matrix.

[0054] The measurement equation is as follows:

[0055]

[0056] In the formula, For attitude measurement noise, Noise for speed measurement.

[0057] Step two is as follows: After the sub-inertial navigation system detects the start of erection command, it judges the variance of the zero bias estimation of the gyro accelerometer. If it converges, it records the current estimation result; stops error estimation and resets the sub-inertial navigation system's transfer alignment filter; and restores the coordinate system of the sensitive axis of the IMU inside the sub-inertial navigation system to its original state (a coordinate system that is roughly consistent with the sensitive axis of the main inertial navigation IMU after flipping).

[0058] The zero bias of the gyroscope after restoring it to its original state can be calculated using the following formula.

[0059]

[0060]

[0061] In the formula, for The transpose of .

[0062] Step three specifically involves: after the sub-inertial navigation system detects that the system has been erected, the heading and attitude of the main inertial navigation system are used as the initial values ​​of the heading and attitude. The velocity and position of the main inertial navigation system after the arm compensation are used as the initial values ​​of velocity and position. The zero bias result of the gyroscope and accelerometer estimated by the horizontal state is used as the initial value. Then, a 15-dimensional state Kalman filter is established to estimate the zero bias of the gyroscope and accelerometer, as well as the attitude error and velocity error, through "attitude + velocity" matching.

[0063] Step 3: The state equation and measurement equation used are the same as in Step 1.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dynamic transfer alignment method suitable for attitude flipping, characterized in that, include: After the sub-inertial navigation system is powered on, it receives the flip status, the working status of the main inertial navigation system, the directional attitude of the main inertial navigation system, and the speed information of the main inertial navigation system. If the main inertial navigation system has completed the initial alignment and is in normal working condition, it executes the transfer alignment process; otherwise, the sub-inertial navigation system is in the ready state. The steps for transferring alignment are as follows: Step 1: In the horizontal state, switch to the horizontal state IMU coordinate system for transfer alignment estimation, gyroscope addition, and zero bias. Step 2: Stop filtering during the flipping process and save the zero-bias estimation results; Step 3: After flipping to the correct position, switch to the vertical IMU coordinate system, use the zero bias estimated in the horizontal state as the initial value, and restart the alignment transfer.

2. The dynamic transfer alignment method for attitude flipping according to claim 1, characterized in that: Step one specifically involves: with the sub-inertial navigation system in a horizontal state, rotating the coordinate system of the IMU sensitive axis inside the sub-inertial navigation system by 90 degrees around the lateral axis, switching it to a coordinate system that is roughly consistent with the sensitive axis of the main inertial navigation system IMU; the sub-inertial navigation system uses the heading attitude of the main inertial navigation system as the initial value of heading attitude, and uses the velocity and position of the main inertial navigation system after arm compensation as the initial values ​​of velocity and position, and then establishes a 15-dimensional state Kalman filter to estimate the zero bias of the gyroscope and accelerometer through "attitude + velocity" matching; In a horizontal orientation, the coordinate system is rotated using the gyroscope and dial indicator measurements obtained from the sub-inertial navigation system calculations according to the following formula: Construct a state estimation model, and the system state vector X is as follows: In the formula, These are attitude errors, namely, heading angle error, pitch angle error, and roll angle error; This refers to the horizontal velocity error, namely the eastward velocity error and the northward velocity error; Accelerometer zero bias, including X / Y / Z three-axis accelerometer zero bias; Zero bias for gyroscopes, including zero bias for X / Y / Z three-axis gyroscopes; The installation error angle of the sub-inertial navigation system relative to the main inertial navigation system; Here is the state transition matrix. The system noise matrix; The measurement equation is as follows: In the formula, For attitude measurement noise, Noise for speed measurement.

3. The dynamic transfer alignment method for attitude flipping according to claim 1, characterized in that: Step two specifically involves: after the sub-inertial navigation system detects the start of erection command, it judges the variance of the zero bias estimation of the gyro accelerometer. If convergence is achieved, the current estimation result is recorded; error estimation is stopped and the sub-inertial navigation system transfer alignment filter is reset; the coordinate system of the IMU sensitive axis inside the sub-inertial navigation system is restored to its original state. The zero bias of the gyroscope after restoring it to its original state can be calculated using the following formula: In the formula, for The transpose of .

4. The dynamic transfer alignment method suitable for attitude flipping according to claim 1, characterized in that: Step three specifically involves: after the sub-inertial navigation system detects that the system has been erected, the heading and attitude of the main inertial navigation system are used as the initial values ​​of the heading and attitude. The velocity and position of the main inertial navigation system after the arm compensation are used as the initial values ​​of velocity and position. The zero bias result of the gyroscope and accelerometer estimated by the horizontal state is used as the initial value. Then, a 15-dimensional state Kalman filter is established to estimate the zero bias of the gyroscope and accelerometer, as well as the attitude error and velocity error, through "attitude + velocity" matching.

5. The dynamic transfer alignment method for attitude flipping according to claim 1, characterized in that: The state equation and measurement equation used in step three are the same as those in step one.

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