Error self-calibration and compensation method for liquid floated gyro platform type inertial navigation system

Abstract

A method for error self-calibration and compensation of liquid floated gyro platform inertial navigation system is provided. In the condition of static base, the platform is locked at 13 frame angle positions, then the platform is controlled to track inertial coordinate system through the stable loop, and the measurement values of accelerometer and frame angle sensor are collected. The platform attitude angle in the earth coordinate system is calculated by using the platform attitude solution method of inertial navigation system, and is compared with the platform attitude angle measured by the platform frame angle sensor to obtain the attitude misalignment angle observation. The state misalignment angle sequence of each tracking inertial coordinate system process is linearly fitted to obtain the comprehensive angular velocity error of the inertial navigation system at each calibration position. The residual of the zero order, first order and cross term drift error coefficients is solved by using the total least squares algorithm, the estimated value of the measured parameter is corrected, and the self-calibration result of each drift error coefficient is obtained by iterative calculation until the iterative convergence criterion is met.

Description

TECHNICAL FIELD

[0001] The application relates to a liquid floated gyro platform type inertial navigation system error self-calibration and compensation method and belongs to the technical field of inertial navigation. BACKGROUND

[0002] An inertial navigation system measures carrier angular motion and linear motion parameters by using an accelerometer and a gyroscope, and obtains carrier speed, position and attitude information through navigation calculation. According to the establishment mode of an inertial measurement reference, the inertial navigation system can be divided into a platform type inertial navigation system and a strapdown type inertial navigation system.

[0003] The platform type inertial navigation system (also referred to as an inertial platform) installs inertial measurement elements (mainly including a gyroscope and an accelerometer) on the same inertial measurement assembly (hereinafter referred to as a platform body), uses a gyroscope to sense angular motion of the platform body, controls the platform body to track a navigation coordinate system through a rotating frame mechanism, and isolates angular motion of a carrier; and then uses an accelerometer to measure acceleration information (specific force) of the platform body in the navigation coordinate system, and obtains speed and position information of the platform body through integral operation of a navigation computer.

[0004] The liquid floated gyro platform type inertial navigation system controls the platform body to track the navigation coordinate system based on a liquid floated gyroscope. The liquid floated gyroscope is a kind of mechanical rotor type gyroscope, which senses angular motion of the gyroscope relative to an inertial space based on characteristics such as axis fixation and precession, including a full liquid floated gyroscope and a three floated gyroscope. The liquid floated gyro platform type inertial navigation system is currently mainly applied to high-precision application fields such as navigation and guidance of a long-range missile weapon system, and common types include a three-axis frame type platform system and a four-axis frame type platform system, and a typical feature is that the platform body tracks an inertial coordinate system.

[0005] In the application of the inertial navigation system, the errors of the inertial instruments need to be compensated to improve navigation precision. For the inertial navigation system using the liquid floated gyroscope, the error coefficient of the gyroscope is in the form of drift angular velocity relative to the inertial space, including constant drift, drift error proportional to a certain axial overload (first order term), drift error proportional to the square of a certain axial overload (second order term), and drift error proportional to the product of axial overloads (cross term) and the like. Among them, the second order term of the gyroscope is generally not significant in a 1g gravity field environment, and needs to be calibrated under high overload conditions. SUMMARY

[0006] The technical problem to be solved by the application is to overcome the shortcomings of the prior art and solve the problem of liquid floated gyro platform type inertial navigation system error self-calibration and compensation.

[0007] The application achieves the above purpose by the following technical scheme.

[0008] A self-calibration and compensation method for errors in a liquid-floated gyroscope platform-type inertial navigation system is disclosed. Under static base conditions, the platform is locked at 13 frame angle positions. A stabilization loop is then used to control the platform to track the inertial coordinate system, and measurements from accelerometers and frame angle sensors are collected. The attitude angles of the platform in the ground coordinate system are calculated using the platform attitude calculation method of the inertial navigation system. These angles are compared with the attitude angles measured by the platform frame angle sensors to obtain the observed attitude misalignment angles. Linear fitting is performed on the sequence of state misalignment angles during each segment of the inertial coordinate system tracking process to obtain the comprehensive angular velocity error of the inertial navigation system at its respective calibration position. The residuals of the zero-order, first-order, and cross-term drift error coefficients are calculated using the overall least squares algorithm. The estimated values ​​of the measured parameters are corrected, and iterative calculations are performed using the corrected error coefficient estimates until the iterative convergence criterion is met, yielding the self-calibration results for each drift error coefficient. This method can calibrate 21 error coefficients, including zero-order, first-order, and cross-terms of the liquid-floated gyroscope, and estimate the base azimuth angle of the inertial navigation system. By self-calibrating and compensating for the error coefficients, the inertial navigation accuracy of the liquid-floating platform inertial navigation system, as well as the attitude measurement accuracy of the carrier or base, can be improved.

[0009] A method for error self-calibration and compensation in a liquid-floating gyroscope platform-type inertial navigation system, such as... Figure 4 As shown, it includes the following steps:

[0010] (1) Place the liquid-floating gyro platform inertial navigation system under test on a stable foundation with vibration isolation, such as a marble slab or turntable, ensuring that the horizontal attitude angle of the inertial navigation system base is less than 3°. Adjust the attitude angle of the inertial navigation system base and control the frame rotation mechanism to orient the inertial navigation system frame as follows: Figure 1 As shown. For a four-axis platform-type inertial measurement system, one axis needs to be locked to operate in three-axis mode. (Please click...) Figure 1 The diagram shows the definition of the polarity of the accelerometer's X, Y, and Z channels relative to the input axis: X p Z p The axes are perpendicular to each other in an approximately horizontal position, Y p The axis is perpendicular to X. p OZ p Plane, X p Y p Z p An orthogonal coordinate system is formed using the right-hand rule, pointing in the front, top, and right directions of the platform coordinate system, respectively. The zero-point of the frame angle sensor is defined as follows: when the outputs of all frame angle sensors in the inertial navigation system are zero, the base coordinate system and the platform coordinate system approximately coincide, have the same polarity, and X... p Y p Z p Pointing to the front, top, and right directions of the base coordinate system respectively, X p Yp Z p respectively with X F Y F Z F Parallel and with the same polarity. Assume the range of the frame angle sensor measurement value is [0, 360°].

[0011] (2) Control the rotation frame of the inertial navigation system and lock the platform at the frame angle positions shown in Table 1. After locking and stabilizing, enable the system to operate in the navigation application mode that tracks the inertial coordinate system. That is, the rotation control loop of the inertial navigation system controls the platform to stabilize in inertial space based on the angular motion information sensitive by the gyroscope. At this time, the angular velocity of the platform relative to the inertial space is composed of the drift errors of the gyroscope constant drift, first term, and cross term. Collect the measured values ​​of the inertial navigation system frame angle sensors at a frequency of 10Hz or higher for no less than 3 minutes, in degrees. The order of the frame angle positions locked in Table 1 is not required.

[0012] Table 1 Initial values ​​of the angular position of the self-calibration locking frame of the inertial navigation system

[0013] Position number Outer ring frame angle (°) Middle ring frame angle (°) Inner ring frame angle (°) 1 0 0 0 2 0 0 90 3 0 0 180 4 0 0 270 5 270 0 0 6 180 0 0 7 90 0 0 8 90 [Alpha]1 0 9 90 360 - β1 0 10 <![CDATA[β2]]> 0 0 11 360 - β2 0 0 12 0 0 [Alpha]3 13 0 0 360-β3

[0014] Where, β j Values ​​can be taken within the range of [5°, 85°], but typically 15° ≤ |β| is chosen. j |≤75°,j=1,2,3。

[0015] For inertial measurement systems with different frame orientations, it may not be necessary to require... Figure 1 The frame orientation shown is correct, but the initial angular relationship between the inertial measurement system platform and the base during the self-calibration process needs to be consistent with... Figure 1 Same as described in Table 1.

[0016] (3) Perform inertial navigation system self-alignment and determine the azimuth angle α of the inertial navigation system base. p (Taking north by west as positive, i.e., α) p (This refers to the angle of counter-clockwise rotation from geographic north to the X-axis of the inertial navigation system base.)

[0017] (4) Calculate the error coefficient observation matrix for each calibration position and form the overall error coefficient observation matrix. Let the expression for the direction cosine matrix from the ideal table coordinate system to the single-axis turntable base coordinate system be:

[0018]

[0019] In the formula, c ij The elements of the cosine matrix in this direction The frame angle values of the outer ring, the middle ring and the inner ring in the kth row of Table 1, respectively, the error coefficient observation matrix H of the kth self-calibration locking position (k) The calculation method of H is

[0020]

[0021] In the formula, H (k) The calculation result of the kth position should be taken. The superscript T represents the transpose of the matrix. ij The superscript T represents the transpose of the matrix.

[0022] The expression of the error coefficient overall observation matrix is

[0023]

[0024] (5) Calculate the direction cosine matrix from the platform coordinate system p to the geographic coordinate system g at the initial time of tracking the inertial coordinate system navigation at each calibration position:

[0025]

[0026] In the formula, is the base attitude matrix determined by the inertial navigation system self-alignment, is the direction cosine matrix from the platform coordinate system p to the geographic coordinate system g at the initial time t0 of navigation at each position, and the expression is

[0027]

[0028] In the formula, k = 1, 2, … 9; are the measurement values of the outer ring, the middle ring and the inner ring frame angle sensors, respectively, in rad; are the middle ring and the inner ring frame angle zero offsets, respectively, in rad, j = 1, 2, 3; γ ij is the frame non-orthogonal error angle, in rad, i, j = x, y, z.

[0029] (6) Define that the navigation coordinate system i (inertial coordinate system) coincides with the geographic coordinate system g at the initial time, then the direction cosine matrix from the platform coordinate system p to the inertial coordinate system i at the initial time is

[0030]

[0031] (7) At each calibration position, the inertial navigation attitude is solved periodically using the measurement values of the accelerometer of the inertial navigation system in the whole process of tracking the inertial coordinate system navigation, and the specific method is as follows:

[0032] The specific method is as follows: the specific method is as follows: The specific method is as follows: the specific method is as follows:

[0033]

[0034] where k = 1, 2, … 13; K 0j is the bias of the j accelerometer, unit: pulse / s; K 1j is the scale factor of the accelerometer, unit: pulse / (s-g0); E ij is the installation error angle, which represents the influence of the i direction specific force on the j accelerometer measurement, unit: rad; Δ nj is the asymmetric scale error coefficient of the j accelerometer, unit: 1, i, j = x, y, z; calibration parameter K 0j ,E ij ,Δ nj The initial value of K 1j is taken as the factory nominal value of the instrument. is the output value of the j accelerometer at the k position at time t, unit: pulse / s.

[0035] The angular velocity of the platform relative to the inertial space can be calculated from the mathematical model of the gyroscope drift:

[0036]

[0037] where D 0j is the zero-order drift error coefficient of the gyroscope, unit: ° / h; D ij is the first-order drift error coefficient of the gyroscope, unit: ° / h / g; D i2j is the cross-term drift error coefficient related to the product of the j gyroscope and the overload along the two axes other than the i axis of the platform coordinate system, unit: ° / h / g 2 ;

[0038] The expression for calculating the direction cosine matrix of the platform coordinate system p to the inertial coordinate system i at time t+Δt is

[0039]

[0040] where ω j is the j component of , that is,

[0041] The expression for calculating the direction cosine matrix of the inertial coordinate system i to the geographic coordinate system g at time t+Δt is

[0042]

[0043] where ω ie is the angular velocity of the earth, and L is the local latitude. Then the direction cosine matrix of the platform coordinate system p to the geographic coordinate system g is​​ The expression of the above formula is

[0044]

[0045] (8) The direction cosine matrix from the platform coordinate system p to the geographic coordinate system g is calculated using the inertial navigation system frame angle sensor measurement value at time t+Δt

[0046]

[0047] In the formula, m3 is the inner ring frame coordinate system, m2 is the middle ring frame coordinate system, and m1 is the outer ring frame coordinate system. The expression of each matrix factor is as follows:

[0048] ① The direction cosine matrix from the platform coordinate system to the inner ring frame coordinate system is

[0049]

[0050] In the formula, γ zx , γ zy is the non-orthogonal error angle of the inner ring frame.

[0051] ② The direction cosine matrix from the inner ring frame coordinate system to the middle ring frame coordinate system is

[0052]

[0053] In the formula, γ yz is the non-orthogonal error angle of the middle ring frame, is the inner ring frame angle sensor measurement value at time t+Δt, is the inner ring frame angle sensor zero offset.

[0054] ③ The direction cosine matrix from the middle ring frame coordinate system to the outer ring frame coordinate system is

[0055]

[0056] In the formula, γ xy is the non-orthogonal error angle of the platform axis, is the middle ring frame angle sensor measurement value at time t+Δt, is the middle ring frame angle sensor zero offset.

[0057] ④ The direction cosine matrix from the outer ring frame coordinate system to the base coordinate system is

[0058]

[0059] In the formula, is the outer ring frame angle sensor measurement value at time t+Δt.

[0060] (9) Since the base coordinate system attitude angle measured by the frame angle sensor is not affected by the drift error of the gyroscope, it can be used as a reference for the error angle tracked by the gyroscope-controlled stable loop in the inertial coordinate system. The expression of the attitude misalignment angle of the optical liquid-floated gyroscope platform inertial navigation system at time t+Δt is

[0061]

[0062] where φ j is the inertial navigation system j-direction attitude misalignment angle, j=x, y, z.

[0063] (10) The attitude misalignment angles of all N navigation calculation periods in each flight navigation process are calculated, and the comprehensive drift error angular velocity of each calibration position is calculated using a linear fitting algorithm. The expression of the j-direction comprehensive drift error angular velocity of the inertial navigation system at the kth position is

[0064]

[0065] where j=x, y, z, n=1, 2, 3, …, N, N is the number of navigation calculation periods at each position; Δt is the navigation calculation period, unit: s; and the comprehensive drift error angular velocity vector at the kth position is

[0066]

[0067] (11) The estimated value of the error coefficient is calculated using the total least squares algorithm:

[0068] X=(H T H) -1 H T Z=[X1 X2 … X 22 ] T

[0069] where Z is the total observation composed of X1, X2, …, XN, and its expression is

[0070]

[0071] (12) The estimated value of the calibrated parameter and the base attitude angle is corrected using the least squares estimation result, and the calculation method is as follows:

[0072] Base azimuth angle:

[0073]

[0074] Gyroscope zero-order term:

[0075] D fx | (l+1) =D fx |(l) +X2

[0076] D fy | (l+1) =D fy | (l) +X3

[0077] D fz | (l+1) =D fz | (l) +X4

[0078] Gyroscope primary term:

[0079] D xx | (l+1) =D xx | (l) +X5

[0080] D xy | (l+1) =D xy | (l) +X6

[0081] D xz | (l+1) =D xz | (l) +X7

[0082] D yx | (l+1) =D yx | (l) +X8

[0083] D yy | (l+1) =D yy | (l) +X9

[0084] D yz | (l+1) =D yz | (l) +X 10

[0085] D zx | (l+1) =D zx | (l) +X 11

[0086] D zy | (l+1) =D zy | (l) +X 12

[0087] D zz | (l+1) =Dzz | (l) +X 13

[0088] Gyroscope cross terms:

[0089] D x2x | (l+1) = D x2x | (l) +X 14

[0090] D y2x | (l+1) = D y2x | (l) +X 15

[0091] D z2x | (l+1) = D z2x | (l) +X 16

[0092] D x2y | (l+1) = D x2y | (l) +X 17

[0093] D y2y | (l+1) = D y2y | (l) +X 18

[0094] D z2y | (l+1) = D z2y | (l) +X 19

[0095] D x2z | (l+1) = D x2z | (l) +X 20

[0096] D y2z | (l+1) = D y2z | (l) +X 21

[0097] D z2z | (l+1) = D z2z | (l) +X 22

[0098] In the above formula, l is the iteration calculation number, represents the result of the lth error separation, l = 0, 1, 2, …, wherein l = 0 represents the initial value of the error coefficient.

[0099] (13) using the modified error coefficient estimate to perform iteration calculation, i.e. repeating steps (5)-(12) until each component X of the correction amount X (least square estimation result) satisfies the iteration convergence criterion: i (X i is the convergence criterion value of the ith dimension component), the modified error coefficient estimate of the current least square estimation result is the self-calibration result of each error coefficient. (i = 1, 2, …, 22) In engineering applications, the iteration number N can be directly taken as 5-10 times.

[0100] Compared with the prior art, the present application has the following beneficial effects:

[0101] The present application can realize self-calibration of all zero-order term, first-order term and cross term drift error coefficients of the liquid floated gyro platform type inertial navigation system, and can also accurately estimate the base azimuth angle of the inertial navigation system. Through self-calibration and compensation of the error coefficients, the inertial navigation precision of the liquid floated platform type inertial navigation system and the carrier or base attitude measurement precision can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0102] Figure 1 is the frame orientation of the frame type inertial navigation system of the present application.

[0103] Figure 2 is the measurement value curve of the frame angle sensor in the process of tracking inertial space at each calibration position simulated in the simulation verification of the present application.

[0104] Figure 3 is the measurement value curve of the accelerometer in the process of tracking inertial space at each calibration position simulated in the simulation verification of the present application.

[0105] Figure 4 is the flowchart of the method of the present application. DETAILED DESCRIPTION

[0106] In order to make the purpose, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0107] Based on the simulation test, the specific embodiment and application effect of the present application are given, a liquid floated gyro platform type inertial navigation system error self-calibration and compensation method, assuming that the frame orientation of the inertial navigation system is as follows: Figure 1 ​The error coefficients of the inertial navigation system are normal distribution random constants. The equivalent value range of the accelerometer is 5000±50 pulses / (s·g0), the error value range of the nominal value used in the calibration of the present method is [-1e-5, 1e-5], the value range of the accelerometer zero offset is [-0.25, 0.25] pulses / s, the error value range of the nominal value used in the calibration of the present method is [-1e-5, 1e-5], the value range of the accelerometer asymmetric scale error is [-1e-5, 1e-5] g0, the value range of the accelerometer installation error is [-180, 180] arcseconds, the error value range of the nominal value used in the calibration of the present method is [-5, 5] arcseconds, the value range of the frame non-orthogonal error angle is [-180, 180] arcseconds, the error value range of the nominal value used in the calibration of the present method is [-5, 5] arcseconds, the value range of the frame angle sensor zero offset is [-180, 180] arcseconds, the error value range of the nominal value used in the calibration of the present method is [-5, 5] arcseconds, the value range of the inertial navigation system base horizontal attitude angle is [-3°, 3°], the base azimuth angle is uniformly distributed in the range of [0°, 360°), the error value range of the self-alignment result used in the calibration of the present method is [-5, 5] arcseconds for the horizontal alignment error and [-60, 60] arcseconds for the azimuth alignment error. The gyro drift error coefficients to be calibrated of the inertial navigation system are normal distribution random constants, the value range of the zero-order term is [-0.1, 0.1]° / h, the value range of the first-order term is [-0.1, 0.1]° / h / g0, and the value range of the cross term is [-0.1, 0.1]° / h / g0 2 The self-calibration initial values of the zero-order term, the first-order term and the cross term are all 0.

[0108] The self-calibration locking frame angle positions used in the self-calibration are shown in Table 2.

[0109] Table 2 Self-calibration locking frame angle position initial values of the inertial navigation system

[0110] Position number Outer ring frame angle (°) Middle ring frame angle (°) Inner ring frame angle (°) 1 0 0 0 2 0 0 90 3 0 0 180 4 0 0 270 5 270 0 0 6 180 0 0 7 90 0 0 8 90 30 0 9 90 330 0 10 30 0 0 11 330 0 0 12 0 0 30 13 0 0 330

[0111] The angular position relationship of the platform inertial navigation system liquid floating gyro drift angular velocity model simulation table body relative to the geographic coordinate system is simulated, the real-time output values of each frame angle sensor are calculated according to the platform frame angle direction cosine matrix mathematical model and the frame angle axis non-orthogonal error model, the gravitational acceleration is projected into the table coordinate system, the accelerometer combined actual sensitive specific force is obtained, the accelerometer specific force real-time measurement values at each calibration position are calculated according to the accelerometer specific force output error model, the data sampling frequency is 100 Hz, and the data acquisition time at each position is 3 min. The accelerometer output values and the frame angle output values in the process of tracking the inertial coordinate system of each section generated in the simulation are shown in Figs. Figure 2 、 Figure 3 .

[0112] Before starting the self-calibration procedure, the self-alignment of the liquid floated gyro platform type inertial navigation system is performed to determine the platform base attitude angle. Herein is introduced a coarse alignment method of analytical expression: (its principle is the known technology in the field of inertial navigation, and does not belong to the features of the present application.)

[0113] The platform body of the platform type inertial navigation system is locked at the zero position of the frame angle by the control of the stabilizing loop and the torque, and the 3-minute accelerometer measurement value and the gyro torque current are collected after the locking is stabilized. (In the torque locking and stabilized state, the torque current of the liquid floated gyro is equivalent to its angular velocity measurement value.) The average value of the specific force vector measurement value of the three accelerometers (unit: m / s 2 ) and the average value of the angular velocity measurement value vector of the three gyros (unit: rad / s) are calculated. Then the calculation method of the platform body attitude matrix for locking the frame angle zero position is

[0114]

[0115] The calculation method of the attitude matrix of the base of the inertial navigation system is

[0116]

[0117] The simulated generated accelerometer measurement value is processed by the method of steps (2)-(11) of the present application, the iteration number N=10 is taken, and the self-calibration result is shown in Table 3.

[0118] Table 3 Self-calibration simulation test result

[0119]

[0120]

[0121] The simulation test result verifies the effectiveness of the method of the present application.

[0122] The contents not described in detail in the specification of the present application are the known technology of the person skilled in the art.

[0123] Although the present application has been disclosed with the above preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not depart from the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application.

Claims

1. A method for error self-calibration and compensation of a liquid floated gyro platform type inertial navigation system, characterized in that, The method comprises the following steps: (1) placing the liquid floated gyro platform type inertial navigation system to be measured on a stable base with shock isolation function, so that the horizontal attitude angle of the base of the inertial navigation system is less than 3°; (2) controlling a rotating frame of the inertial navigation system, locking the platform body at 13 different frame angle positions respectively, and collecting measurement values of a frame angle sensor of the inertial navigation system; (3) performing self-alignment of the inertial navigation system, and determining a base azimuth angle of the inertial navigation system; (4) calculating error coefficient observation matrices at the respective calibration positions, and composing an overall error coefficient observation matrix; (5) calculating a direction cosine matrix of the platform body coordinate system to the geographic coordinate system at an initial time of tracking inertial coordinate system navigation at the respective calibration positions; (6) defining that the navigation coordinate system coincides with the geographic coordinate system at the initial time, and determining a direction cosine matrix of the platform body coordinate system to the inertial coordinate system; (7) periodically performing inertial navigation attitude solution by using measurement values of an accelerometer of the inertial navigation system in the whole process of tracking the inertial coordinate system navigation at the respective calibration positions; (8) calculating the direction cosine matrix of the platform body coordinate system to the geographic coordinate system by using the measurement values of the frame angle sensor of the inertial navigation system; (9) calculating an attitude misalignment angle of the liquid floated gyro platform type inertial navigation system according to a reference benchmark of an error angle of the measurement attitude of the inertial coordinate system tracked by the gyro controlled stable loop; (10) obtaining attitude misalignment angles of all N navigation calculation periods in the navigation process of each flight segment, calculating comprehensive drift error angular velocities at the respective calibration positions by using a linear fitting algorithm, and determining comprehensive drift error angular velocities of the inertial navigation system in different directions at the respective calibration positions; (11) obtaining an estimated value of the error coefficient by using a total least square algorithm; (12) correcting estimated values of the calibrated parameters and the base attitude angle by using the estimated value of the error coefficient; (13) performing iterative calculation by using the corrected estimated values, and repeating steps (5)-(12) until a correction amount in the estimated value of the error coefficient meets an iterative convergence criterion.

2. The error self-calibration and compensation method of liquid floated gyro platform type inertial navigation system according to claim 1, characterized in that, In step (2), the frame angle positions locked in the self-calibration of the inertial navigation system are shown in the following table: The sequence of the frame angle positions locked in the data acquisition in the table has no requirement.

3. The error self-calibration and compensation method of liquid floated gyro platform type inertial navigation system according to claim 2, characterized in that, In step (4), the expression of the direction cosine matrix of the platform body coordinate system to the single-axis turntable base coordinate system in an ideal case is as follows: In the formula, c ij is the element of the direction cosine matrix, a p is the base azimuth angle of the inertial navigation system, The error coefficient observation matrix H (k) of the kth position is calculated as follows: where H (k) The middle c ij The calculation result of the kth position; the superscript T represents the transpose of the matrix; The expression of the overall error coefficient observation matrix is as follows:

4. The method of claim 3, wherein, In step (5), the direction cosine matrix of the platform body coordinate system p to the geographic coordinate system g at an initial time of tracking the inertial coordinate system navigation at the respective calibration positions is as follows: wherein is the base attitude matrix determined by the inertial navigation system self-alignment, is the direction cosine matrix of the platform coordinate system p to the geographic coordinate system g at the initial time t0 of each position navigation, expressed as: where k = 1, 2, … 13; respectively, the middle ring, the inner ring frame angle zero offset; γ ij frame non-orthogonal error angle, i, j = x, y, z.

5. The error self-calibration and compensation method of liquid floated gyro platform type inertial navigation system according to claim 4, characterized in that, In step (7), the inertial navigation attitude solution is periodically performed by using the measurement values of the accelerometer of the inertial navigation system in the whole process of tracking the inertial coordinate system navigation at the respective calibration positions, and the specific method is as follows: The specific method is as follows: where k = 1, 2,... 13; K 0j is the accelerometer bias in j direction; K 1j is the accelerometer scale factor; E ij is the installation error angle, representing the effect of the i direction specific force on the j direction accelerometer measurement; Δ nj is the asymmetric scale error coefficient of the j direction accelerometer, i, j = x, y, z; K 0j , E ij , Δ nj is initialized to 0, K 1j is initialized to the factory nominal value of the instrument; is the output of the j direction accelerometer at time t in the k position; The specific method is as follows: where D 0j is the zero-order drift error coefficient of the gyroscope; D ij is the first-order drift error coefficient of the gyroscope; D i2j is the cross-term drift error coefficient related to the product of the overloads along the two axes other than the i-axis of the platform coordinate system of the j gyroscope The expression of the direction cosine matrix of the platform coordinate system p to the inertial coordinate system i at time t+Δt is ​ where ω j is the j- component of the vector ​ The expression for the direction cosine matrix from the inertial coordinate system i to the geographical coordinate system g at time t + Δt is The expression for the direction cosine matrix from the inertial coordinate system i to the geographical coordinate system g at time t + Δt is In the formula, ω ie Let L be the Earth's angular velocity and L be the local latitude; then the direction cosine matrix from the platform coordinate system p to the geographic coordinate system g is... The expression is 6. The method of claim 5, wherein, In step (8), the direction cosine matrix p to g of the platform coordinate system p to the geographic coordinate system g is calculated using the inertial navigation system frame angle sensor measurement at time t+Δt The angular velocity of the platform body relative to the inertial space can be calculated according to a gyro drift mathematical model: In the formula, m3 is an inner ring frame coordinate system, m2 is a middle ring frame coordinate system, and m1 is an outer ring frame coordinate system; the expressions of the matrix factors are as follows: The direction cosine matrix from the table coordinate system to the inner ring frame coordinate system is In the formula, γ zx ,γ zy is the non-orthogonal error angle of the inner ring frame. The direction cosine matrix from the inner ring frame coordinate system to the middle ring frame coordinate system is In the formula, γ yz is a non-orthogonal error angle of the inner ring frame, is a measurement value of the inner ring frame angle sensor at time t+Δt, is a zero offset of the inner ring frame angle sensor; The direction cosine matrix from the middle ring frame coordinate system to the outer ring frame coordinate system is In the formula, γ xy is the non-orthogonal error angle of the axle of the table body, is the measurement value of the middle ring frame angle sensor at time t+Δt, is the zero offset of the middle ring frame angle sensor; The direction cosine matrix from the outer ring frame coordinate system to the base coordinate system is In the formula, is the outer ring frame angle sensor measurement at time t + Δt.

7. The error self-calibration and compensation method of liquid floated gyro platform type inertial navigation system according to claim 6, characterized in that, In step (9), the table base coordinate system attitude angle measured by the frame angle sensor is not affected by the gyro drift error, and thus can be used as a reference for the error angle tracked by the gyro-controlled stable loop to measure the attitude of the inertial coordinate system. Therefore, the expression of the attitude misalignment angle of the liquid-floated gyro platform type inertial navigation system at time t+Δt is where φ j is the attitude misalignment angle of the inertial navigation system j, j = x, y, z.

8. The method of claim 7, wherein, In step (10), the attitude misalignment angles of all N navigation calculation periods in the flight navigation process are calculated, and the comprehensive drift error angular velocity at each calibration position is calculated using the linear fitting algorithm. The expression of the comprehensive drift error angular velocity of the inertial navigation system at the kth position in the j direction is In the formula, j=x, y, z, n=1, 2, 3, …, N, N is the number of navigation calculation periods at each position; Δt is the navigation calculation period; and the comprehensive drift error angular velocity vector at the kth position is 9. The method of claim 8, wherein, In step (11), the total least squares algorithm is used to obtain the estimated value of the error coefficient: X = (H T H) -1 H T Z = [X1 X2... X 22 ] T wherein Z is δω (k) the total observed quantity of constituents, expressed as 10. The method of claim 9, wherein, In step (12), the least squares estimation result is used to correct the estimated value of the calibrated parameters and the base attitude angle, and the calculation method is as follows: Base azimuth angle: Gyroscope zero-order term: D 0x | (l+1) = D 0x | (l) + X2 D 0y | (l+1) = D 0y | (l) + X3 D 0z | (l+1) = D 0z | (l) + X4 Gyroscope first-order term: D xx | (l+1) = D xx | (l) + X5 D xy | (l+1) = D xy | (l) + X6 D xz | (l+1) = D xz | (l) + X7 D yx | (l+1) = D yx | (l) + X8 D yy | (l+1) = D yy | (l) + X9 D yz | (l+1) = D yz | (l) + X 10 D zx | (l+1) = D zx | (l) + X 11 D zy | (l+1) = D zy | (l) + X 12 D zz | (l+1) = D zz | (l) + X 13 Gyroscope cross term: D x2x | (l+1) = D x2x | (l) + X 14 D y2x | (l+1) = D y2x | (l) + X 15 D z2x | (l+1) = D z2x | (l) + X 16 D x2y | (l+1) = D x2y | (l) + X 17 D y2y | (l+1) = D y2y | (l) + X 18 D z2y | (l+1) = D z2y | (l) + X 19 D x2z | (l+1) = D x2z | (l) + X 20 D y2z | (l+1) = D y2z | (l) + X 21 D z2z | (l+1) = D z2z | (l) + X 22 In the above formulas, l is the number of iteration calculations, representing the result of the lth error separation, l=0, 1, 2, …, wherein l=0 represents the initial value of the error coefficient.

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