A method for self-calibration of mounting angle between frames of a rotary inertial navigation system

Abstract

The application discloses a kind of rotary inertial navigation system frame installation deviation angle self-calibration method, first, rotary inertial navigation system power preheating;Second, rotary inertial navigation system control frame is rotated according to the rotation scheme designed, while recording gyroscope original data;Finally, original data is processed, compensates gyroscope error, and uses the step difference between the angular velocity output mean in positive rotation and reverse rotation period to rotary inertial navigation system frame installation deviation angle is calibrated and compensated step by step.The application provides rotary inertial navigation system frame installation deviation angle self-calibration method, uses the rotation mechanism of rotary inertial navigation system self and realizes the self-calibration of frame installation deviation angle, without disassembly, engineering practicability is strong;Directly using compensated gyroscope output, without navigation solution;Calibration process is simple and fast, and calibration precision is high, and it has important significance for improving inertial navigation system attitude output precision.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of frame installation bias angle calibration of rotary inertial navigation system, and particularly relates to a frame installation bias angle self-calibration method of rotary inertial navigation system. BACKGROUND

[0002] The inertial navigation system is a self-contained navigation positioning and orientation system, which is based on an inertial measurement unit composed of an accelerometer and a gyroscope and uses an acceleration meter and a gyroscope to measure the position, velocity and attitude of a moving object.

[0003] The rotary inertial navigation system introduces a rotating frame, and can automatically compensate for constant and slowly varying errors of inertial devices through rotation modulation, so as to improve the position and velocity accuracy of the system; meanwhile, the rotary inertial navigation system can stimulate errors through a reasonable rotation strategy, so as to realize self-calibration without external facilities such as a turntable. However, the frame installation bias angle caused by frame processing and assembly errors will cause a large oscillation in the output carrier attitude, and the attitude output accuracy of the rotary inertial navigation system will be reduced.

[0004] In occasions where an attitude reference is required to be provided for a carrier task load, and in occasions where attitude transmission is required between a main inertial navigation system and a sub inertial navigation system, such as transmission alignment, cooperative navigation and the like, the output attitude accuracy of the inertial navigation system is required. Calibrating and compensating for the frame installation bias angle has important engineering significance for improving the attitude output accuracy and improving the alignment accuracy between the main inertial navigation system and the sub inertial navigation system. The existing frame installation bias angle calibration methods mainly use attitude as a measurement, and use least squares, Kalman filtering and the like based on modeling, which has problems such as complex modeling and unclear physical meaning. SUMMARY

[0005] The application aims at the above-mentioned problems, and provides a frame installation bias angle self-calibration method of rotary inertial navigation system, which realizes simple and rapid self-calibration and compensation of the frame installation bias angle of the rotary inertial navigation system. The method uses a rotation mechanism of the rotary inertial navigation system itself, designs a corresponding rotation scheme to stimulate errors, and does not require external devices such as a turntable; directly uses the gyro output after error compensation, and does not require navigation calculation, so as to realize high-precision calibration of the frame installation bias angle; and the oscillation of the attitude output of the rotary inertial navigation system after compensation is obviously suppressed.

[0006] To achieve the above-mentioned purposes, the application adopts the following technical scheme:

[0007] A frame installation bias angle self-calibration method of rotary inertial navigation system, comprising the following steps:

[0008] Step 1: controlling the rotary inertial navigation system to rotate according to a designed frame installation bias angle self-calibration rotation scheme, continuously rotating forward and backward around the inner frame shaft, the middle frame shaft and the outer frame shaft at a constant angular velocity, and recording original gyro data.

[0009] Step 2: Process the raw data and compensate for the gyroscope error. Then, use the step difference between the average angular velocity output values ​​during the forward and reverse rotation cycles to perform step-by-step calibration and compensation for the installation angle between the frames of the rotating inertial navigation system. After compensation, the attitude output oscillation of the rotating inertial navigation system is significantly suppressed.

[0010] Furthermore, in step 1, the self-calibration rotation scheme for the installation angle between frames is specifically divided into the following three steps:

[0011] (1) The middle frame and the outer frame are locked at 0°. The rotating inertial navigation system rotates around the inner frame axis for N consecutive cycles of forward and reverse rotation at a constant angular velocity.

[0012] (2) The inner frame and outer frame are locked at 0°, and the rotating inertial navigation system rotates around the middle frame axis for N consecutive cycles of forward and reverse rotation at a constant angular velocity;

[0013] (3) The inner frame and middle frame are locked at 0°, and the rotating inertial navigation system rotates around the outer frame axis for N cycles of continuous forward and reverse rotation at a constant angular velocity.

[0014] Furthermore, in step 2, the step-by-step calibration and compensation method is as follows:

[0015] The calibration method is as follows:

[0016] (1) When the rotating inertial navigation system rotates about the inner frame axis, the installation deflection angle β between the inertial measurement coordinate system and the inner frame coordinate system. ZX and β ZY The calculation method is as follows:

[0017]

[0018] in and These represent the average angular velocity of the S-frame in the x-direction when the inner frame rotates clockwise and counterclockwise, respectively. and These represent the average angular velocities in the y-direction of the S-frame during clockwise and counterclockwise rotations of the inner frame, respectively. ∫(·) represents the integral operation, and φ z It is the absolute rotation angle value of the frame grating output within a forward or reverse rotation cycle;

[0019] N forward and reverse cycles yield 2N-1 step differences, and the final calibration result is:

[0020]

[0021] β ZX_i and β ZY_i The installation offset angle between the inertial measurement coordinate system and the inner frame coordinate system calibrated for the i-th step difference. and The average installation angle between the inertial measurement coordinate system and the inner frame coordinate system calibrated for 2N-1 step differences, N is the number of positive and reverse rotation periods of the system in step 1, i=1, 2, 3…2N-1.

[0022] (2) When the rotary inertial navigation system rotates around the middle frame shaft, the above-mentioned β ZX and β ZY The compensation method of the calibration results of the two installation angles is as follows: XY and β XZ The calculation method of the installation angles β

[0023]

[0024] and are the average values of the y-direction angular velocity of the r1 system when the middle frame rotates forward and reversely, respectively, and are the average values of the z-direction angular velocity of the r1 system when the middle frame rotates forward and reversely, respectively, φ x is the absolute rotation angle value of the middle frame grating output in a positive or reverse rotation period;

[0025] The final calibration result is:

[0026]

[0027] (3) When the rotary inertial navigation system rotates around the outer frame shaft, the above-mentioned β ZX , β ZY , β XY and β XZ The compensation method of the calibration results of the two installation angles is as follows: YX and β YZ The calculation method of the installation angles β

[0028]

[0029] and are the average values of the x-direction angular velocity of the r2 system when the outer frame rotates forward and reversely, respectively, and are the average values of the z-direction angular velocity of the r2 system when the outer frame rotates forward and reversely, respectively, φ y is the absolute rotation angle value of the outer frame grating output in a positive or reverse rotation period;

[0030] The final calibration result is:

[0031]

[0032] The compensation method is as follows:

[0033] Rotary inertial navigation system inter-frame installation bias angle is obtained through attitude conversion matrix Compensation, The expression of the above formula is respectively:

[0034]

[0035]

[0036]

[0037]

[0038] Wherein, is the attitude conversion matrix from s system to b system, is the attitude conversion matrix from s system to r1 system, is the attitude conversion matrix from r1 system to r2 system, is the attitude conversion matrix from r2 system to r3 system, is the attitude conversion matrix from r3 system to b system; φ1, φ2, φ3 are absolute rotation angle values output by the inner frame, middle frame and outer frame of the rotary inertial navigation system respectively; the inter-frame installation bias angle β ZX , β ZY , β XY , β XZ , β YX and β YZ are obtained through the above calibration process, and I is a unit matrix.

[0039] Compared with the prior art, the present application has the following advantages:

[0040] (1) The self-calibration method for the inter-frame installation bias angle of the rotary inertial navigation system proposed in the present application greatly reduces the influence of vortex by averaging the step difference of the average angular velocity output in the forward and reverse rotation periods, and realizes high-precision calibration of the inter-frame installation bias angle. The self-calibration and compensation model established through theoretical derivation is simpler than the model established by filtering method; the step difference is calculated, and the physical meaning is clear.

[0041] (2) The present application designs a self-calibration rotation scheme using the rotary structure of the inertial navigation system itself, without the need for external facilities such as a turntable, without the need for navigation solution, and the calibration process is simple and the data processing calculation is simple.

[0042] (3) The present application has high calibration precision for the inter-frame installation bias angle, good compensation effect after the result is brought into the system, and the attitude precision is greatly improved. After the calibrated inter-frame installation bias angle is compensated into the rotary inertial navigation system, the system attitude output oscillation is reduced from a maximum of 700" to below 15".

[0043] (4) The application has wide application range, and can delete the rotation process according to the number of frames, and is popularized to various inertial navigation systems with rotation mechanisms. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 A flowchart of the self-calibration method for the installation bias angle between frames of the rotating inertial navigation system (taking a three-axis rotating inertial navigation system as an example for illustration);

[0045] Figure 2 A schematic diagram of the self-calibration rotation scheme for the installation bias angle between frames of the three-axis rotating inertial navigation system;

[0046] Figure 3 A schematic diagram of the installation bias angle between frames of the three-axis rotating inertial navigation system;

[0047] Figure 4 A schematic diagram of the rotating frame structure of the three-axis rotating optical fiber inertial navigation system according to an embodiment of the application, wherein 1 is an inner frame, 2 is a middle frame, and 3 is an outer frame, and the system can rotate around three axes;

[0048] Figure 5 A comparison of the attitude output before and after compensation of the three-axis rotating optical fiber inertial navigation system around the inner frame axis according to an embodiment of the application; the upper graph is a comparison of the pitch angle output before and after compensation, and the lower graph is a comparison of the roll angle output before and after compensation;

[0049] Figure 6 A comparison of the attitude output before and after compensation of the three-axis rotating optical fiber inertial navigation system around the middle frame axis according to an embodiment of the application; the upper graph is a comparison of the roll angle output before and after compensation, and the lower graph is a comparison of the heading angle output before and after compensation;

[0050] Figure 7 A comparison of the attitude output before and after compensation of the three-axis rotating optical fiber inertial navigation system around the outer frame axis according to an embodiment of the application; the upper graph is a comparison of the pitch angle output before and after compensation, and the lower graph is a comparison of the heading angle output before and after compensation. DETAILED DESCRIPTION

[0051] In order to make the objectives, technical solutions, and advantages of the present application clearer, further detailed descriptions will be given to the present application in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0052] As shown in Figure 1 , 2 , the self-calibration method for the installation bias angle between frames of the rotating inertial navigation system is as follows (taking a three-axis rotating inertial navigation system as an example for illustration):

[0053] First, the rotary inertial navigation system is powered and preheated;

[0054] Second, the rotary inertial navigation system is controlled to self-calibrate the installation angle between frames according to a designed frame installation angle self-calibration rotation scheme, continuously rotates in positive and reverse directions at a constant angular velocity around the inner frame shaft, the middle frame shaft and the outer frame shaft respectively, and records original data of the gyroscope;

[0055] Finally, after processing the original data and compensating the gyroscope error, the installation angle between frames of the rotary inertial navigation system is stepwise calibrated and compensated by using the step difference between the average angular velocity outputs in the positive and reverse rotation periods, and the oscillation of the attitude output of the rotary inertial navigation system after compensation is obviously suppressed, thereby improving the attitude output precision of the system.

[0056] As shown in Figure 4 , taking a three-axis rotary inertial navigation system as an example, the rotary frame structure of the three-axis rotary optical fiber inertial navigation system in the application is composed of an inner frame 1, a middle frame 2 and an outer frame 3, and the system can rotate around three axes.

[0057] As shown in Figure 2 , the frame installation angle self-calibration rotation scheme includes three steps. Step 1: the middle frame and the outer frame are locked at 0°, the system rotates in N continuous positive and reverse directions around the inner frame shaft at an angular velocity of 6° / s; Step 2: the inner frame and the outer frame are locked at 0°, the system rotates in N continuous positive and reverse directions around the middle frame shaft at an angular velocity of 6° / s; Step 3: the inner frame and the middle frame are locked at 0°, the system rotates in N continuous positive and reverse directions around the outer frame shaft at an angular velocity of 6° / s. In this embodiment, the number of positive and reverse rotation periods N is 4, and 8 min is required for each step.

[0058] The method for stepwise calibrating and compensating the installation angle between frames of the rotary inertial navigation system by using the step difference between the average angular velocity outputs in the positive and reverse rotation periods is as follows:

[0059] In step 1, when the rotary inertial navigation system rotates around the inner frame shaft, due to the installation angle, the rotation angular velocity will be projected onto two directions perpendicular to the inner frame shaft in the inertial measurement coordinate system s:

[0060]

[0061] and are the angular velocities of s in the x direction when the inner frame rotates in positive and reverse directions respectively, and are the angular velocities of s in the y direction when the inner frame rotates in positive and reverse directions respectively, ω r1 is the rotation angular velocity of the inner frame, which is a constant value, β ZX and β ZY are the installation angles between the inertial measurement coordinate system and the inner frame coordinate system, as shown in Figure 3The calculation method of β ZX and β ZY is as follows:

[0062]

[0063] That is, the output angular velocity in the positive rotation period and the output angular velocity in the reverse rotation period are averaged respectively, and the step difference between the two is used to calculate β ZX and β ZY . The average can eliminate the influence of the earth rotation angular velocity and part of the vortex, and ∫(·) is the integral operation, φ z is the integral of ω r1 in a positive rotation or reverse rotation period, that is, the absolute rotation angle value of the inner frame grating output. N positive and reverse rotation periods can obtain 2N-1 step difference values, and the final calibration result is:

[0064]

[0065] β ZX_i and β ZY_i are the installation bias angles between the inertial measurement coordinate system and the inner frame coordinate system calibrated by the i-th step difference, and are the average installation bias angles between the inertial measurement coordinate system and the inner frame coordinate system calibrated by 2N-1 step differences. N is the number of positive and reverse rotation periods of the system, and i=1, 2, 3…2N-1. Multiple sets of average can effectively reduce the influence of residual vortex.

[0066] In step 2, when the rotary inertial navigation system rotates around the middle frame shaft, due to the existence of the installation bias angle, the rotation angular velocity will be projected onto two directions perpendicular to the middle frame shaft in the inner frame coordinate system r1:

[0067]

[0068] and are the angular velocities of r1 y direction when the middle frame rotates positively and reversely, and are the angular velocities of r1 z direction when the middle frame rotates positively and reversely, ω r2 is the rotation angular velocity of the middle frame, which is a constant value, β XY and β XZ are the installation bias angles between the inner frame coordinate system and the middle frame coordinate system, as shown in Figure 3 . The calculation method of β XY and β XZ is as follows:

[0069]

[0070] The above r1 angular velocity outputs are all compensated by β ZX and βZY Output after two installation offset angles. φ x ω is within a forward or reverse rotation cycle r2 The integral of this is the absolute rotation angle value output by the mid-frame grating. The final calibration result is:

[0071]

[0072] β XY_i and β XZ_i The installation offset angle between the inner frame coordinate system and the middle frame coordinate system, calibrated for the i-th step difference. and The mean installation offset angle between the inner frame coordinate system and the middle frame coordinate system, calibrated for 2N-1 step differences.

[0073] In step 3, when the rotating inertial navigation system rotates around the outer frame axis, due to the installation offset angle, the rotational angular velocity will be projected onto two directions perpendicular to the outer frame axis in the middle frame coordinate system r2:

[0074]

[0075] and These represent the angular velocities of the r2 system in the x-direction when the outer frame rotates clockwise and counterclockwise, respectively. and These represent the angular velocities in the z-direction of the r2 system when the outer frame rotates clockwise and counterclockwise, respectively, ω. r3 The outer frame rotational angular velocity is a constant value, β. YX and β YZ It is the installation offset angle between the middle frame coordinate system and the outer frame coordinate system, such as Figure 3 As shown. Then β YX and β YZ The calculation method is as follows:

[0076]

[0077] All the above r2 series angular velocity outputs are compensated for β. ZX β ZY β XY and β XZ Output after four installation angles. φ y ω is within a forward or reverse rotation cycle r3 The integral of this is the absolute rotation angle value output by the outer frame grating. The final calibration result is:

[0078]

[0079] β YX_i and β YZ_i The installation offset angle between the middle frame coordinate system and the outer frame coordinate system, calibrated for the i-th step difference. and The average installation bias angle between the middle frame coordinate system and the outer frame coordinate system calibrated for 2N-1 step differences.

[0080] Specifically, the compensation method is:

[0081] The inter-frame installation bias angle is converted by a pose conversion matrix Compensate into the system, The expressions are respectively:

[0082]

[0083]

[0084]

[0085]

[0086] wherein, is the pose conversion matrix from s system to b system, is the pose conversion matrix from s system to r1 system, is the pose conversion matrix from r1 system to r2 system, is the pose conversion matrix from r2 system to r3 system, is the pose conversion matrix from r3 system to b system; φ1, φ2, φ3 are absolute rotation angle values output by the inner frame, the middle frame and the outer frame of the rotary inertial navigation system respectively; the inter-frame installation bias angles β ZX , β ZY , β XY , β XZ , β YX and β YZ are obtained from the above calibration process, and I is a unit matrix.

[0087] Figure 3 The definitions of the inter-frame installation bias angles β ZX , β ZY , β XY , β XZ , β YX , β YZ of the three-axis rotary inertial navigation system are given. Wherein, O-X s Y s Z s is the inertial measurement coordinate system of the system, i.e. s system, the X s OY s plane is defined by the x and y accelerometer sensitive axes, the OX s axis points to the projection of the x gyro sensitive axis on the X s OY s plane, and the OY s axis points to the projection of the y gyro sensitive axis on the X sOY s in the plane along the OX s axis and the y accelerometer sensitive axis is an acute angle, OZ s axis and the OX s axis, OY s axis together form a right-handed rectangular coordinate system. is the inner frame axis coordinate system, i.e. r1 system, and the inner frame axis when each frame angle is 0 is axis, OX s in the projection on the vertical plane is axis, axis, axis is determined by the right-hand rule. is the middle frame axis coordinate system, i.e. r2 system, and the middle frame axis when each frame angle is 0 is axis, inner frame coordinate system in the projection on the vertical plane is axis, axis, axis is determined by the right-hand rule. is the outer frame axis coordinate system, i.e. r3 system, and the outer frame axis when each frame angle is 0 is axis, middle frame coordinate system in the projection on the vertical plane is axis, axis, axis is determined by the right-hand rule.

[0088] Table 1 shows the calibration result statistics of β ZX , β ZY , β XY , β XZ , β YX , β YZ in one experiment. When the positive and negative rotation period is 4, 7 steps can be obtained, corresponding to 7 results. As can be seen from Table 1, the results obtained from different steps are consistent, and the range is better than 0.5", which shows the reliability of the step method proposed in the application.

[0089] Table 2 shows the experimental results of 4 repeated experiments of self-calibration of the installation bias angle between the frames of the three-axis rotary inertial navigation system. According to Table 2, the calibration results of the self-calibration method of the installation bias angle between the frames of the rotary inertial navigation system proposed in the application are good in repeatability, and the calibration accuracy is better than 1".

[0090] Table 1 shows the experimental results of self-calibration of the installation bias angle between the frames of the three-axis rotary inertial navigation system.

[0091]

[0092] Table 2 shows the experimental results of self-calibration of the installation bias angle between the frames of the three-axis rotary inertial navigation system.

[0093]

[0094] Figure 5 , Figure 6 and Figure 7 A comparison of attitude output before and after installation of the frame between the compensation frames of a three-axis rotating inertial navigation system is presented, corresponding to the rotation process of the system around the inner frame axis, the middle frame axis and the outer frame axis, respectively; Figure 5 The top image shows a comparison of pitch angle output before and after compensation, while the bottom image shows a comparison of roll angle output before and after compensation. Figure 6 The top image shows a comparison of roll angle output before and after compensation, while the bottom image shows a comparison of yaw angle output before and after compensation. Figure 7 The upper figure shows a comparison of pitch angle output before and after compensation, and the lower figure shows a comparison of yaw angle output before and after compensation. The dashed line represents the attitude output before the system compensates for the angle of deflection between the frames, and the solid line represents the attitude output after compensation. θ represents the pitch angle, γ represents the roll angle, and ψ represents the yaw angle. The three-axis rotating inertial navigation system is initially placed in the northeast direction. When it rotates around the inner frame axis in both forward and reverse directions, as shown in formula (1), it will excite β. ZX and β ZY Errors cause output pitch and roll angle errors, such as Figure 5 The dashed line shows an oscillation in the form of sine and cosine, with a fluctuation amplitude of up to about 200". The frame installation deflection angle obtained by the calibration method proposed in this invention is compensated into the system according to formulas (10)-(13). After compensation, the fluctuation amplitudes of pitch angle and roll angle are both less than 15". When rotating around the middle frame axis in both forward and reverse directions, as shown in formula (4), β will be excited. XY and β XZ Errors cause errors in the output roll angle and yaw angle, such as Figure 6 The dashed line shows an oscillation in the form of sine and cosine, with a fluctuation amplitude of up to about 700". The frame installation deflection angle obtained by the calibration method proposed in this invention is compensated into the system according to formulas (10)-(13). After compensation, the fluctuation amplitudes of the roll angle and heading angle are both less than 15". When rotating around the outer frame axis in both forward and reverse directions, as shown in formula (7), β will be excited. YX and β YZ Errors cause errors in the output pitch and yaw angles, such as Figure 7 The dashed line shows an oscillation in the form of sine and cosine, with a fluctuation amplitude of up to about 400". The frame installation deflection angle obtained by the calibration method proposed in this invention is compensated into the system according to (10)-(13). After compensation, the fluctuation amplitude of pitch angle and heading angle is less than 15".

[0095] Figure 5 , Figure 6 and Figure 7The reliability of the self-calibration method of the mounting angle between frames of the rotary inertial navigation system is proved, and the accuracy of the calibration result and the effectiveness of the compensation model are verified.

[0096] The part of the application not disclosed in detail belongs to the known technology in the art.

[0097] Although the above describes the specific embodiments of the present application in detail, so that those skilled in the art can understand the present application, it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, as long as various changes are within the spirit and scope of the present application defined and determined by the appended claims, all the inventions utilizing the concept of the present application are included in the protection.

Claims

1. A method for self-calibration of mounting misalignment angle between frames of a rotary inertial navigation system, characterized in that, The method comprises the following steps: Step 1, controlling the rotary inertial navigation system to self-calibrate the designed frame installation bias angle rotation scheme, continuously and reversely rotating around the inner frame shaft, the middle frame shaft and the outer frame shaft at a constant angular velocity, and recording the original data of the gyroscope; Step 2, processing the original data, compensating the gyroscope error, and using the step difference between the average angular velocity output in the positive rotation and reverse rotation periods to step by step calibrate and compensate the frame installation bias angle of the rotary inertial navigation system, so that the oscillation of the attitude output of the rotary inertial navigation system is obviously suppressed after compensation; In the step 2, the step by step calibration and compensation method is as follows: The calibration method is specifically as follows: (1) When the rotary inertial navigation system rotates around the inner frame axis, the installation angle between the inertial measurement coordinate system (i.e., s system) and the inner frame coordinate system (i.e., x system) is calculated as follows: the installation angle between the two coordinate systems and is calculated as follows: (1) wherein, and are the average values of the angular velocity of the inner frame in the x direction during forward and reverse rotation, respectively, and are the average values of the angular velocity of the inner frame in the y direction during forward and reverse rotation, respectively, is an integral operation, is the absolute rotation angle value of the inner frame during a forward or reverse rotation period. N positive and negative rotation periods obtain 2N-1 step difference values, and the final calibration result is: (2) and the installation bias angle between the inertial measurement coordinate system and the inner frame coordinate system calibrated for the i th step difference, and the installation bias angle between the inertial measurement coordinate system and the inner frame coordinate system calibrated for the 2N-1 step differences, N is the number of forward and reverse rotation periods of the system in step 1, ; (2) When the rotary inertial navigation system rotates around the middle frame axis, the above-mentioned and After compensation of the calibration results of the two installation bias angles, the inner frame coordinate system and the middle frame coordinate system are the installation bias angle between the coordinate systems and The calculation method is as follows: (3) and are the average values of the angular velocity in the x direction when the middle frame is rotated forward and backward, respectively is the average value of the angular velocity in the y direction, and are the average values of the angular velocity in the x direction when the middle frame is rotated forward and backward, respectively is the average value of the angular velocity in the z direction, is the absolute rotation angle value of the middle frame grating output in a forward or backward rotation period The final calibration result is: (4) (3) When the rotary inertial navigation system rotates about the outer frame axis, the above-mentioned , , and After compensation for the calibration results of the four installation offset angles, the coordinate systems of the middle frame and the outer frame are... Installation offset between systems and The calculation method is as follows: (5) and are the average values of the angular velocity in the x direction when the outer frame is rotated forward and backward, respectively is the average value of the angular velocity in the x direction, and are the average values of the angular velocity in the z direction when the outer frame is rotated forward and backward, respectively is the average value of the angular velocity in the z direction, is the absolute rotation angle value of the outer frame grating output in one forward or backward rotation period The final calibration result is: (6) The compensation method is as follows: Inter-frame installation angle of rotary inertial navigation system through attitude conversion matrix Compensation, The expressions are respectively:​ (7) (8) (9) (10) wherein, is a posture conversion matrix from the s system to the b system, is a posture conversion matrix from the s system to the b system, is a posture conversion matrix from the s system to the b system, is a posture conversion matrix from the s system to the b system, is a posture conversion matrix from the s system to the b system; , , are absolute rotation angle values output by inner, middle and outer ring grating of the rotary inertial navigation system, respectively; installation bias angle between frames , , , , and are obtained from the above calibration process, and I is an identity matrix.

2. The method of claim 1, wherein: In the step 1, the frame installation bias angle self-calibration rotation scheme is specifically divided into the following three steps: (1) the middle frame and the outer frame are locked at 0°, the rotary inertial navigation system continuously and reversely rotates around the inner frame shaft at a constant angular velocity for N periods; (2) the inner frame and the outer frame are locked at 0°, the rotary inertial navigation system continuously and reversely rotates around the middle frame shaft at a constant angular velocity for N periods; (3) the inner frame and the middle frame are locked at 0°, the rotary inertial navigation system continuously and reversely rotates around the outer frame shaft at a constant angular velocity for N periods.

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