Transfer alignment method based on relative inertial navigation

Abstract

The invention designs a transfer alignment method based on relative inertial navigation, in particular relates to a relative inertial navigation transfer alignment method based on inertial navigation relative position measurement correction state quantity, and belongs to the technical field of transfer alignment. Aiming at the condition that the conventional relative inertial navigation transfer alignment only adopts simulation data verification, semi-physical experiment simulation is adopted for verification, and aiming at the condition that the conventional relative inertial navigation transfer alignment only can process the condition that an initial attitude misalignment angle is a small angle, a system error equation of the relative inertial navigation transfer alignment is newly deduced; the condition that the initial relative attitude angle is a large angle can be processed; the transfer alignment based on relative inertial navigation can guarantee high alignment precision and also can give consideration to rapidity of alignment, verification of the transfer alignment is simulation verification in the past, the authenticity of the transfer alignment is to be commercialized, and according to the method, actual inertial navigation data is adopted for semi-physical simulation verification, and the effectiveness of the transfer alignment is further verified.

Description

Technical Field

[0001] The invention discloses a transfer alignment method based on relative inertial navigation, in particular to a relative inertial navigation transfer alignment method based on inertial navigation relative position measurement and correction state quantity, belonging to the technical field of transfer alignment. Background Art

[0002] Since the advent of Newton's three laws of mechanics in 1687, they have not only laid the foundation for classical mechanics, but also provided a theoretical basis for the development of inertial navigation. The initial application of the inertial navigation system was the V-2 rocket during World War II. Today, the inertial navigation system has matured and is widely used in military and civilian fields, such as missiles, submarines, indoor positioning, and geodetic surveys. According to whether there is a physical platform, the inertial navigation system can be divided into platform type and strapdown type. Due to its unique advantages, the strapdown inertial navigation system uses a computing virtual platform instead of a physical platform to achieve miniaturization, lightweight and low cost. Due to the improvement of technical strength, its accuracy and reliability can also be guaranteed. As a result, strapdown inertial navigation has gradually developed into the mainstream direction of inertial navigation systems.

[0003] Before working, the inertial navigation system needs to determine its initial attitude, speed and position information, all of which need to be obtained through initial alignment. Therefore, the speed of the initial alignment of the inertial navigation determines the startup time of the inertial navigation, and the alignment accuracy directly affects the navigation solution accuracy. Its importance is self-evident. Transfer alignment is an extension of the initial alignment of the moving base. Usually there is at least one high-precision main inertial navigation system and a sub-inertial navigation system with lower accuracy. The alignment process is the same as the initial alignment and can be divided into two stages. The coarse alignment process directly assigns the main inertial navigation information to the sub-inertial navigation as its initial information, which is also called primary binding. The fine alignment process uses the precise information provided by the main inertial navigation to correct the sub-inertial navigation error, so that the sub-inertial navigation obtains more accurate initial information.

[0004] During the transfer alignment of the airborne master-slave inertial navigation, the wings will inevitably bend and deform due to the influence of airflow, self-maneuvering, etc. The flexural deformation is usually complex and unknown, and has a great relationship with the external environment, fuselage materials, etc. It is difficult to accurately model it, which will have a certain impact on the alignment accuracy of traditional transfer alignment methods such as attitude matching and angular velocity matching. However, the transfer alignment based on relative inertial navigation does not need to model the flexural deformation. It only uses the information output by the master-slave inertial navigation inertial sensor to solve the relative motion, and relies on relative position filtering to correct the state quantity, thereby realizing the accurate calculation of attitude information under the sub-insertial navigation system.

[0005] The measurement equation of relative inertial navigation transfer alignment is relatively fixed, obtained by subtracting the calculated relative position of the master inertial navigation from the nominal relative position of the master inertial navigation, and is in a linear form. There are two forms of derivation of the relative inertial navigation transfer alignment system error equation. By making a small angle assumption for the initial relative attitude angle, an approximately linear relative inertial navigation error equation is derived, which has a better effect on the transfer alignment when the initial relative attitude angle is a small angle; without restricting the size of the initial relative attitude angle, a nonlinear relative inertial navigation transfer alignment system error equation can be derived, and nonlinear filtering can be used for processing, which can also obtain a better transfer alignment effect.

[0006] In the existing relative inertial navigation transfer alignment research, only the linear relative inertial navigation transfer alignment system error equation has been derived, and all of them have been verified using simulation data, lacking actual inertial navigation data verification. Therefore, it is necessary to verify it using the actual output data of the inertial navigation and derive the nonlinear relative inertial navigation transfer alignment system equation. Summary of the invention

[0007] In view of the above-mentioned prior art, the present invention aims to improve the existing linear relative inertial navigation transfer alignment system model, re-derive a nonlinear relative inertial navigation transfer alignment system model suitable for when the initial relative attitude error angle is large, and verify the original relative inertial navigation transfer alignment with actual inertial navigation data.

[0008] In order to solve the above technical problems, a transfer alignment method based on relative inertial navigation of the present invention comprises the following steps:

[0009] Step 1: Establish a linear system model for relative inertial navigation transfer including state equations and measurement equations. The specific state equations are:

[0010]

[0011]

[0012] Among them, δξ is the relative attitude error, δD is the pseudo-relative velocity error, δr is the relative position error, is the gyroscope constant bias, is the gyroscope random drift vector, is the constant zero bias of the accelerometer, is the accelerometer random drift vector, is the attitude matrix between the master and slave INS, is the projection of the angular velocity of the main inertial navigation coordinate system relative to the inertial system in the main inertial navigation coordinate system, f s is the specific force of the sub-INS, W is the white noise with a mean value of 0, and F is the state transfer matrix.

[0013] The measurement equation is:

[0014]

[0015] Z=HX+V

[0016] H=[0 3×3 0 3×3 I 3×3 0 3×3 0 3×3 ]

[0017] in, represents the calculated value of the relative position, L represents the nominal value of the relative position, and L f represents the flexural displacement, Z represents the quantity measurement, which is obtained by subtracting the calculated value of the relative position from the nominal value, H represents the measurement matrix, and V represents the measurement noise;

[0018] Step 2: Establish the state equation of the relative inertial navigation transfer alignment nonlinear system model:

[0019]

[0020] Step 3: Use an existing navigation vehicle test vehicle, which is equipped with an industrial computer, uninterruptible power supply, equipment fixing plate, GPS antenna, laser strapdown inertial navigation, fiber strapdown inertial navigation and other equipment. The industrial computer is used as the host computer to send instructions to the inertial navigation. The laser strapdown inertial navigation is used as the experimental verification system, and the fiber strapdown inertial navigation / GPS combination is used as the reference system to provide reference navigation information for accuracy assessment. The fiber strapdown inertial navigation is used as the main inertial navigation, and the laser strapdown inertial navigation is used as the sub-inertial navigation. Carry out sports car experiments to obtain actual inertial navigation data.

[0021] Step 4: Design experimental verification. For linear relative inertial navigation transfer alignment, semi-physical simulation verification is used; for nonlinear relative inertial navigation transfer alignment, pure simulation verification is used.

[0022] Beneficial effects:

[0023] The transfer alignment based on relative inertial navigation can ensure high alignment accuracy while taking into account the rapidity of alignment. In the past, the verification of this type of transfer alignment was all simulation verification, and its authenticity is questionable. This invention uses actual inertial navigation data for semi-physical simulation verification to further verify its effectiveness. At the same time, in view of the fact that the existing relative inertial navigation transfer alignment can only handle the situation where the initial relative attitude angle is a small angle, the relative inertial navigation transfer alignment system equation is re-derived so that it can handle the situation where the relative attitude angle is a large angle. The beneficial effects of the present invention are summarized as follows:

[0024] 1. In view of the fact that relative inertial navigation transfer alignment was previously verified only by simulation data, the present invention uses semi-physical experimental simulation for verification;

[0025] Second, in view of the fact that the existing relative inertial navigation transfer alignment can only handle the situation where the initial attitude misalignment angle is a small angle, the present invention re-derives the system error equation of the relative inertial navigation transfer alignment so that it can handle the situation where the initial relative attitude angle is a large angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Transfer alignment flow chart for relative inertial navigation;

[0027] Figure 2 is the relative attitude error relationship diagram;

[0028] Figure 3 is the relative position error relationship diagram;

[0029] Figure 4 It is the three-axis posture diagram of the vehicle trajectory;

[0030] Figure 5 It is the vehicle trajectory map;

[0031] Figure 6 is the sub-INS attitude angle error;

[0032] Figure 7 is the relative attitude angle error of the master inertial navigation;

[0033] Figure 8 is the trajectory diagram of the carrier movement;

[0034] Fig. 9 is the sub-INS attitude angle error;

[0035] Fig.10 is the relative attitude angle error of the master inertial navigation. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be understood that the terms "upper", "middle", "outer", "inner" and the like indicating directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0038] The specific implementation modes of the present invention will be further described below in conjunction with the accompanying drawings.

[0039] Combination Figure 1 , the specific implementation mode of the present invention comprises the following steps:

[0040] Step 1: Establish a relative inertial navigation transfer quasi-linear system model including state equations and measurement equations;

[0041] The specific steps are as follows:

[0042] The first step is to establish the state equation of the system. In order to derive the system error equation for relative inertial navigation transfer alignment, we define the following coordinate system. The main inertial navigation coordinate system is represented as m, the sub-inertial navigation coordinate system is represented as s, and the inertial coordinate system is represented as i. By derivation, the error model of the inertial navigation system can be obtained:

[0043]

[0044]

[0045] Where δξ is the relative attitude error, δD is the pseudo-relative velocity error, and δr is the relative position error. is the gyroscope constant bias, is the gyroscope random drift vector, is the constant zero bias of the accelerometer, is the accelerometer random drift vector, is the attitude matrix between the master and slave INS, is the projection of the angular velocity of the main inertial navigation coordinate system relative to the inertial system in the main inertial navigation coordinate system, f s The comparison of sub-inertial navigation.

[0046] Take the relative attitude angle δξ, the pseudo velocity error δD, the relative position error δr, the constant deviation of the gyroscope and accelerometer is the state variable. According to equations (1) to (5), the following state equation can be obtained:

[0047]

[0048] Where F is the state transfer matrix, and W is white noise with an assumed mean of 0.

[0049] The second step is to establish the measurement equation of the system. Usually, the accuracy of the main inertial navigation is several orders of magnitude higher than that of the sub-inertial navigation. It is assumed that the navigation information output by the main inertial navigation is a true value without error, and the main inertial navigation coordinate system coincides with the carrier coordinate system. The relative position between the main and sub-inertial navigation is measured in advance and used as the nominal value. Figure 2 , the measurement equation is as follows:

[0050]

[0051] Z=HX+V (11)

[0052] H=[0 3×3 0 3×3 I 3×3 0 3×3 0 3×3 ] (12)

[0054] In the formula, represents the calculated value of the relative position, L represents the nominal value of the relative position, and L f represents the flexural displacement,

[0055] Z represents the measurement, which is obtained by subtracting the calculated value of the relative position from the nominal value. H represents the measurement matrix. V

[0056] Indicates the measurement noise. 0 3×3 is a 3×3 dimensional zero matrix. I3 represents the unit diagonal matrix.

[0057] Discretizing equations (7) and (11), we can obtain the following discrete time state space model of relative inertial navigation transfer alignment:

[0058] X k+1 =F k X k +W k (13)

[0059] Z k+1 =H k+1 X k+1 +V k+1 (14)

[0060] The accuracy of the sub-inertial navigation is usually low, and it is unable to complete the initial alignment with high accuracy independently. It needs to use the navigation parameter information output by the main inertial navigation to transfer the alignment in order to obtain high-precision attitude information. According to the above relative inertial navigation transfer alignment error equation, a suitable filter is designed to estimate the state quantity, thereby correcting the relative motion quantity solved by the relative inertial navigation and obtaining more accurate sub-inertial navigation attitude information.

[0061] Step 2: Establish the state equation of the relative inertial navigation transfer alignment nonlinear system model:

[0062] When the initial relative attitude angle is large, the relationship between the calculated relative attitude matrix and the ideal relative attitude matrix between the master and slave inertial navigation systems is as follows:

[0063]

[0064]

[0065] Taking the derivative of both ends of equation (16) simultaneously, we can obtain:

[0066]

[0067] Further transformation of formula (17) yields:

[0068]

[0069] In the above formula, since the accuracy of the main inertial navigation inertial device is much higher than that of the sub-inertial navigation, it is considered that the navigation parameter information output by the main inertial navigation is accurate, that is, The angular velocity measurement of the sub-inertial navigation system is

[0070] Expanding formula (18) yields:

[0071]

[0072] Formula (19) can also be written as follows:

[0073]

[0074] In addition Multiply both ends of equation (19) by the matrix Substituting into (20) we can obtain:

[0075]

[0076] Rewriting equation (21) into vector form, the relative attitude differential equation is as follows:

[0077]

[0078] The pseudo velocity differential equation is as follows:

[0079]

[0080] In summary, by combining equations (22), (23), (5), (2), and (1), we can obtain the nonlinear system equation as follows:

[0081]

[0082] Step 3: Obtain the actual inertial navigation output data of the master and slave inertial navigation transfer alignment, such as Figure 3 , Figure 4As shown. A dedicated navigation vehicle test vehicle is used, which is equipped with industrial computers, uninterruptible power supply, equipment fixing plate, GPS / RTK antenna, laser strapdown inertial navigation, fiber strapdown inertial navigation and other equipment. The industrial computer is used as the host computer to send instructions to the inertial navigation. The laser strapdown inertial navigation is used as the experimental verification system, and the fiber strapdown inertial navigation / GPS combination is used as the reference system to provide reference navigation information for accuracy assessment. Among them, the fiber strapdown inertial navigation is used as the main inertial navigation, and the laser strapdown inertial navigation is used as the sub-inertial navigation. Firstly, the static self-alignment of fiber optic inertial navigation for 300s is performed to obtain the rough initial attitude, and the obtained attitude is used as the initial attitude of the master inertial navigation; the master and sub-inertial navigation are combined with GPS for a total of 2300s, and the attitude value of the master and sub-inertial navigation at each sampling moment is recorded. The installation error angle between the master and sub-inertial navigation is [-0.17°, 0.04°, 1.42°] calculated by attitude matrix multiplication (the inverse matrix of the sub-inertial navigation attitude matrix multiplied by the main inertial navigation attitude matrix), which is used as the reference for the subsequent transfer alignment installation error angle; the arm between the master and sub-inertial navigation is [0, -0.3, 0.1] meters, and the data in the time period of 850s-1030s are selected to test the relative inertial navigation transfer alignment algorithm and the speed plus attitude matching transfer alignment algorithm.

[0083] Step 4: Design experimental verification. For linear relative inertial navigation transfer alignment, semi-physical simulation verification is used; for nonlinear relative inertial navigation transfer alignment, pure simulation verification is used.

[0084] The semi-physical simulation conditions of linear relative inertial navigation transfer alignment are shown in step 3. The parameters of the gyroscope and accelerometer used are as follows:

[0085]

[0086]

[0087] The flow chart of relative inertial navigation transfer alignment is as follows Figure 5 The semi-physical simulation results are shown in Figure 6 , Figure 7 As shown in the figure, the root mean square value of the relative attitude error and the sub-INS attitude error is used as the measurement index. The statistical interval is 40s-180s. The statistics of the sub-INS relative attitude error and attitude error RMS are as follows:

[0088]

[0089] Pure simulation conditions for nonlinear relative inertial navigation transfer alignment: The initial attitude of the carrier is θ = 0°, γ = 0° and ψ = -90°, and multiple turns are performed, with each turn angle of 70°. The flight lasts for 180 seconds, and the trajectory diagram is as follows: Figure 8As shown. The initial position is 30°N, 120°E, and 1000m high. The initial velocity is 200m / s. The flexural deformation is a second-order Markov process with a standard deviation of [2′, 2′, 2′]. The correlation time is 5s. The sampling frequency of the main and sub-inertial navigation systems is 200Hz. The arm length is [5, 0.5, 1]m. The measurement value of the main inertial navigation inertial sensor is the true value, and the error of the sub-inertial navigation inertial sensor is set as follows:

[0090]

[0091] In order to simulate the situation that the initial relative attitude error angle of the sub-INS is large misalignment angle, large azimuth misalignment angle and small misalignment angle, the installation deviation angles between the master and sub-INS are [30°, 30°, 30°], [0.5°, 0.5°, 30°], and [0.5°, 0.5°, 0.5°] respectively. When the initial relative attitude error angle is large misalignment angle, large azimuth misalignment angle and small misalignment angle, the legend is marked with LMA, LAMA and SMA respectively, and the true value is abbreviated as TV. Fig. 9 and Fig.10 The results of nonlinear relative inertial navigation transfer alignment are shown, and the RMS statistics of the sub-inertial navigation attitude error and the relative attitude error are as follows:

[0092]

[0093] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0094] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A transfer alignment method based on relative inertial navigation, characterized in that: The steps include: A linear system model of relative inertial navigation transfer including state equation and measurement equation is established. The specific state equation is: Among them, δξ is the relative attitude error, δD is the pseudo-relative velocity error, δr is the relative position error, is the gyroscope constant bias, is the gyroscope random drift vector, is the constant zero bias of the accelerometer, is the accelerometer random drift vector, is the attitude matrix between the master and slave INS, is the projection of the angular velocity of the main inertial navigation coordinate system relative to the inertial system in the main inertial navigation coordinate system, f s is the specific force of the sub-INS, W is the white noise with a mean value of 0, and F is the state transfer matrix.

2. A transfer alignment method based on relative inertial navigation according to claim 1, characterized in that: The measurement equation is: Z=HX+V H=[0 3×3 0 3×3 I 3×3 0 3×3 0 3×3 ] in, represents the calculated value of the relative position, L represents the nominal value of the relative position, and L f represents the flexural displacement, Z represents the measurement, which is obtained by subtracting the calculated value of the relative position from the nominal value, H represents the measurement matrix, and V represents the measurement noise.

3. The transfer alignment method based on relative inertial navigation according to claim 2, characterized in that: The state equation of the relative inertial navigation transfer to the nonlinear system model is established as follows:

4. The transfer alignment method based on relative inertial navigation according to claim 3, characterized in that: Use the latest navigation vehicle test vehicle, which is equipped with industrial computer, uninterruptible power supply, equipment fixing plate, GPS antenna, laser strapdown inertial navigation, optical fiber strapdown inertial navigation and other equipment; The industrial computer is used as the host computer to send instructions to the inertial navigation system; The laser strapdown inertial navigation system is used as the experimental verification system, and the fiber-optic strapdown inertial navigation system / GPS combination is used as the reference system to provide reference navigation information for accuracy assessment; The fiber strapdown inertial navigation system is used as the main inertial navigation system, and the laser strapdown inertial navigation system is used as the sub-inertial navigation system. Conduct sports car experiments to obtain actual inertial navigation data.

5. The transfer alignment method based on relative inertial navigation according to claim 4, characterized in that: Experimental verification is designed. Semi-physical simulation verification is used for linear relative inertial navigation transfer alignment, and pure simulation verification is used for nonlinear relative inertial navigation transfer alignment.

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