Quick alignment method based on virtual gyroscope and accelerometer

Abstract

The invention discloses a quick alignment method based on a virtual gyroscope and an accelerometer, which comprises the following steps: a strapdown inertial navigation system performs coarse alignment under a carrier inertial navigation system according to bound initial position information of an aircraft, and constructs an initial attitude matrix of the strapdown inertial navigation system; building a mathematical model of the virtual gyroscope and the virtual accelerometer, and obtaining virtual output values of the gyroscope and the accelerometer through the mathematical model by using the collected output values of the gyroscope and the accelerometer; the strapdown inertial navigation system carries out inertial navigation calculation by using virtual output values of a gyroscope and an accelerometer, wherein the calculation comprises updating of an attitude matrix, a speed and a position; performing fine alignment by using a Kalman filter, and performing fine correction on the attitude matrix by using a fine alignment result; the finely corrected attitude matrix, the position and the speed are used for subsequent inertial navigation of the strapdown inertial navigation system. According to the method, the time of fine alignment can be greatly shortened, and the alignment longitude is improved.

Description

Technical Field

[0001] The invention relates to the field of strapdown inertial technology, and in particular to a rapid alignment method based on a virtual gyroscope and an accelerometer, which is suitable for rapid alignment of high-precision strapdown inertial navigation systems on various rocket-propelled aircraft before launch. Background Art

[0002] At present, the use of strapdown inertial navigation systems to perform attitude and full-course corrections on rocket-propelled aircraft can effectively increase their range and significantly improve their landing accuracy, becoming a major trend in the development of rocket-propelled aircraft.

[0003] With the advancement of technology, the cost of strapdown inertial navigation systems using medium and high precision fiber optic gyroscopes and accelerometers is becoming lower and lower, and the size is becoming smaller and smaller, making them more and more widely used in rocket-propelled aircraft airborne applications.

[0004] The strapdown inertial navigation system needs to be initially aligned when working: determine the attitude matrix at the initial moment so that the mathematical platform coordinate system and the navigation coordinate system coincide. Initial alignment can be divided into coarse alignment and fine alignment according to the stage; it can be divided into static base alignment and dynamic base alignment according to the motion state of the base; it can be divided into autonomous alignment and non-autonomous alignment according to the degree of dependence on external information. The accuracy and time of initial alignment are the two most important technical indicators.

[0005] The strapdown inertial navigation system on rocket-propelled aircraft usually adopts a static base alignment scheme. The alignment process is coarse alignment first, and then fine alignment using Kalman filtering. During alignment, the data of gyroscopes and accelerometers must be collected in real time, and the alignment time usually takes more than 150 seconds. As the preparation time requirements for rocket-propelled aircraft become shorter and shorter, the traditional strapdown inertial navigation initial alignment scheme cannot meet the requirements. Summary of the invention

[0006] The purpose of the present invention is to provide a fast alignment method based on a virtual gyroscope and an accelerometer, so as to greatly shorten the time of precise alignment and improve the alignment longitude.

[0007] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0008] A fast alignment method based on a virtual gyroscope and an accelerometer, comprising:

[0009] The strapdown inertial navigation system performs rough alignment of the aircraft in the inertial coordinate system according to the bound initial position information of the aircraft, and constructs the initial attitude matrix of the strapdown inertial navigation system;

[0010] Constructing a mathematical model of a virtual gyroscope and a virtual accelerometer, and using the collected output values ​​of the gyroscope and the accelerometer to obtain virtual output values ​​of the gyroscope and the accelerometer through the mathematical model;

[0011] The strapdown inertial navigation system uses the virtual output values ​​of the gyroscope and accelerometer to perform inertial navigation solutions, including the update of attitude matrix, velocity and position;

[0012] A Kalman filter is used for fine alignment, and the attitude matrix is ​​finely corrected based on the fine alignment result; the finely corrected attitude matrix and the position and velocity are used for subsequent inertial navigation of the strapdown inertial navigation system.

[0013] Furthermore, the rough alignment in the inertial coordinate system of the aircraft is performed to construct an initial attitude matrix of the strapdown inertial navigation system, including:

[0014] The attitude matrix is ​​obtained by the direction cosine matrix between the geocentric inertial coordinate system and the navigation coordinate system. , the direction cosine matrix between the solidification inertial coordinate system and the aircraft inertial coordinate system , the direction cosine matrix between the geocentric inertial coordinate system and the solidification inertial coordinate system Multiply them together to get:

[0015] for , decompose it into the direction cosine matrix between the earth coordinate system and the navigation coordinate system , the direction cosine matrix between the geocentric inertial coordinate system and the earth coordinate system The multiplication form is obtained based on the longitude, latitude and time interval of the strapdown inertial navigation system;

[0016] for , determined by solving the direction cosine matrix differential equation using the gyroscope output;

[0017] for , obtained by using the projection of the velocity vector in the geocentric inertial coordinate system and the solidification inertial coordinate system.

[0018] Furthermore, the , obtained by using the projection of the velocity vector in the geocentric inertial coordinate system and the solidification inertial coordinate system, including:

[0019] First determine the projection of gravity acceleration in the geocentric inertial coordinate system , and then in the time period between the current time and the initial time Integrate to obtain the relationship between the aircraft speed and time in the geocentric inertial coordinate system ; Using the output value of the accelerometer in the inertial coordinate system of the aircraft , get the current accelerometer velocity value ; According to the method of orthogonalization of attitude matrix, at different moments , The relationship between aircraft speed and time , , and the corresponding accelerometer velocity value , Obtain .

[0020] Furthermore, the construction of the mathematical model of the virtual gyroscope and the virtual accelerometer uses the collected output values ​​of the gyroscope and the accelerometer to obtain the virtual output values ​​of the gyroscope and the accelerometer through the mathematical model, including:

[0021] First, based on the output values ​​of the gyroscope and accelerometer collected over a period of time, the mean and standard deviation are calculated as follows:

[0022] , ;

[0023] , ;

[0024] In the formula, For the Axis gyro The output value at the moment, ; are the three axes of the gyroscope; , Indicates the total number of sampling moments; For the Axis accelerometer The output value at each moment; and Respectively The mean and standard deviation of the output values ​​of the gyro; and Respectively The mean and standard deviation of the output values ​​of the axis accelerometer;

[0025] The mathematical models of the virtual gyroscope and virtual accelerometer are constructed according to the mean and standard deviation, and the virtual output values ​​are generated:

[0026] ;

[0027] ;

[0028] In the formula, , is the preset noise amplification factor; The standard deviation is Random noise; The standard deviation is Random noise; For the Axis gyro The virtual output value at a moment, For the Axis accelerometer The virtual output value at a certain moment.

[0029] Furthermore, the strapdown inertial navigation system uses virtual output values ​​of the gyroscope and accelerometer to perform inertial navigation solution, wherein the quaternion method is used for attitude matrix update calculation, firstly, based on the angular increments in three directions within the navigation cycle output by the gyroscope, the equivalent angular increments in the three directions are determined; then, the attitude quaternion is updated and normalized using the equivalent angular increments, and the attitude matrix is ​​updated using the normalized quaternion.

[0030] Furthermore, the strapdown inertial navigation system uses the virtual output values ​​of the gyroscope and the accelerometer to perform inertial navigation solution, wherein the speed update method is:

[0031] ;

[0032] ;

[0033] In the formula, For a navigation cycle The velocity increment of the strapdown inertial navigation system in the navigation coordinate system; Virtual output values ​​generated by the mathematical model of the virtual accelerometer Projection in the navigation coordinate system; is the projection of the Earth's rotation angular rate in the navigation coordinate system; The angular rate of rotation of the navigation coordinate system caused by the motion of the aircraft; is the speed of the strapdown inertial navigation system at time k-1; is the projection of the gravity acceleration vector in the navigation coordinate system; is the speed of the strapdown inertial navigation system at the current moment k.

[0034] Furthermore, the strapdown inertial navigation system uses the virtual output values ​​of the gyroscope and the accelerometer to perform inertial navigation solution, wherein the position update method is:

[0035] ;

[0036] ;

[0037] ;

[0038] In the formula, , are the latitudes of the strapdown inertial navigation system at the current time k and time k-1 respectively; , are the longitudes of the strapdown inertial navigation system at the current time k and time k-1 respectively; , are the altitudes of the strapdown inertial navigation system at the current time k and time k-1 respectively; It is the navigation solution cycle; , , are the velocities of the strapdown inertial navigation system in the north, east and celestial directions at the current time k in the navigation coordinate system, respectively; , , are the north, east and celestial velocities of the strapdown inertial navigation system at time k-1 in the navigation coordinate system, , They represent the meridian radius and the meridian radius respectively.

[0039] Further, the fine alignment using the Kalman filter and the fine correction of the attitude matrix based on the fine alignment result include:

[0040] According to the error equation of strapdown inertial navigation system, the state equation and measurement equation of the precise alignment process are established;

[0041] Construct a recursive equation of a discrete Kalman filter, perform iterative Kalman filter operations through the recursive equation until the specified time is reached, and obtain three misalignment angle estimation values ​​after precise alignment;

[0042] The attitude matrix of the strapdown inertial navigation system is corrected using the estimated value of the misalignment angle, and the corrected attitude matrix is ​​used for inertial navigation.

[0043] Furthermore, the state equation and measurement equation of the precise alignment process are expressed as:

[0044] ;

[0045] ;

[0046] The dot above the parameter indicates the first-order derivative of the parameter. is the state variable, is the measured variable, is the state transfer matrix, and are system noise and measurement noise respectively; is the measurement matrix, It is a noise driven array;

[0047] ;

[0048] ;

[0049] in, It represents the estimated values ​​of misalignment angles in the east, north and sky directions in the navigation coordinate system. It indicates the velocity error in the east, north and sky directions in the navigation coordinate system. Indicates the longitude error, latitude error and altitude error in the position error. is the gyro constant drift error in the x, y, and z directions in the airborne coordinate system, is the constant zero bias error of the accelerometer in the x, y, and z directions in the airborne coordinate system.

[0050] Furthermore, the attitude matrix of the strapdown inertial navigation system is corrected by using the misalignment angle estimation value, which is expressed as:

[0051] ;

[0052] ;

[0053] in, To use the misalignment angle estimate The constructed skew-symmetric matrix; is the corrected attitude matrix; is the identity matrix; is the current posture matrix.

[0054] A terminal device comprises a processor, a memory and a computer program stored in the memory; when the processor executes the computer program, the fast alignment method based on a virtual gyroscope and an accelerometer is implemented.

[0055] A computer-readable storage medium stores a computer program; when the computer program is executed by a processor, the rapid alignment method based on a virtual gyroscope and an accelerometer is implemented.

[0056] Compared with the prior art, the present invention has the following technical features:

[0057] 1. Aiming at the characteristics of high alignment accuracy but long alignment time of traditional precise alignment scheme, the present invention utilizes the powerful computing power of onboard computer to virtualize the output of gyroscope and accelerometer and perform direct calculation, thus saving the time required for collecting data of gyroscope and accelerometer. While retaining the advantage of high alignment accuracy of precise alignment scheme, the disadvantage of long alignment time is overcome.

[0058] 2. In the traditional Kalman filter equation, the noise characteristics of the gyro and accelerometer are usually pre-set, but the strapdown inertial navigation system is affected by the environment in actual application, and sometimes a large deviation occurs. In the present invention, the noise characteristics are calculated using the gyro and accelerometer data collected in real time, avoiding the drawback of large parameter deviation. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a schematic diagram of the process of the present invention;

[0060] Figure 2 A schematic diagram of a rough alignment of an aircraft inertial navigation system according to an embodiment of the present invention;

[0061] Figure 3 A working principle diagram of a navigation solution according to an embodiment of the present invention;

[0062] Figure 4 is an east misalignment angle alignment curve in one embodiment of the present invention;

[0063] Figure 5 is a north misalignment angle alignment curve in one embodiment of the present invention;

[0064] Figure 6 It is an alignment curve of the azimuth misalignment angle in one embodiment of the present invention. DETAILED DESCRIPTION

[0065] The present invention provides a fast alignment method based on a virtual gyroscope and an accelerometer, see the attached Figure 1 ,include:

[0066] Step 1: The strapdown inertial navigation system performs a rough alignment in the inertial coordinate system of the aircraft according to the bound initial position information of the aircraft, and constructs the initial attitude matrix of the strapdown inertial navigation system.

[0067] First, bind the initial position information of the aircraft to the strapdown inertial navigation system, including the longitude ,latitude and height ; Then perform a rough alignment under the inertial navigation system to obtain the initial attitude matrix; rough alignment is an alignment method that uses the slow change of the projection of gravity acceleration on the aircraft inertial coordinate system of the aircraft to extract the north information, which is expressed as:

[0068] ;

[0069] in, is the inertial coordinate system of the aircraft, using the right front upper coordinate system, and the origin of the coordinate is located at the center of mass of the strapdown inertial navigation system; n is the navigation coordinate system, using the northeast celestial coordinate system ENU, and the origin of the coordinate is located at the center of mass of the strapdown inertial navigation system; i is the geocentric inertial coordinate system, and the origin of the coordinate is located at the center of mass of the reference earth model; ib0 represents the solidified inertial coordinate system that is solidified with the aircraft inertial coordinate system at the initial moment; is the direction cosine matrix between the aircraft inertial coordinate system and the navigation coordinate system, that is, the attitude matrix; is the direction cosine matrix between the geocentric inertial coordinate system and the navigation coordinate system; is the direction cosine matrix between the solidification inertial coordinate system and the vehicle inertial coordinate system; is the direction cosine matrix between the geocentric inertial coordinate system and the solidification inertial coordinate system.

[0070] (1-1) Strapdown Inertial Navigation System Longitude ,latitude and time interval To determine:

[0071] ;

[0072] in is the Earth's rotation angular velocity, is the direction cosine matrix between the earth coordinate system e and the navigation coordinate system n; is the direction cosine matrix between the geocentric inertial coordinate system and the earth coordinate system; is the precision parameter, is the latitude, which is replaced by the longitude in the above initial location information ,latitude Perform the solution; and Represent the current time and the initial time respectively.

[0073] (1-2) The output of the gyroscope is determined by solving the direction cosine matrix differential equation:

[0074] ;

[0075] ;

[0076] In the formula express The first-order differential of for The identity matrix of is the output value of the gyroscope; is a skew-symmetric matrix of output values.

[0077] (1-3) Using the projection of the velocity vector in the two coordinate systems i and ib0, we can obtain:

[0078] As the Earth rotates, the acceleration due to gravity Projection in the geocentric inertial coordinate system is a quantity that changes with time and can be expressed as:

[0079] ;

[0080] In time period Integrate the above formula to get the relationship between the speed of the aircraft and time in the geocentric inertial coordinate system: :

[0081] ;

[0082] The output value of the accelerometer is expressed in the aircraft inertial coordinate system as :

[0083] ;

[0084] In the formula, is the accelerometer bias, is the projection of gravity acceleration in the aircraft inertial coordinate system.

[0085] The output value of the accelerometer in the solid inertial coordinate system is , then the velocity value of the accelerometer at time t is for:

[0086] ;

[0087] make , then:

[0088] ;

[0089] It can be seen from the above formula that the direction cosine matrix between the solidification inertial coordinate system and the geocentric inertial coordinate system can be obtained through the velocity vectors in different coordinate systems.

[0090] According to the method of orthogonalization of the attitude matrix, at different times , The relationship between aircraft speed and time , , and the corresponding accelerometer velocity value , , the formula can be constructed as follows:

[0091] ;

[0092] The superscript represents the transposition operation. At this point, the initial attitude matrix of the strapdown inertial navigation system can be obtained: ,like Figure 2 shown.

[0093] Step 2: construct mathematical models of the virtual gyroscope and the virtual accelerometer, and obtain virtual output values ​​of the gyroscope and the accelerometer through the mathematical model using the collected output values ​​of the gyroscope and the accelerometer.

[0094] (2-1) First, based on the output values ​​of the gyroscope and accelerometer collected over a period of time, the mean and standard deviation are calculated as follows:

[0095] , ;

[0096] , ;

[0097] In the formula, For the Axis gyro The output value at the moment, ; are the three axes of the gyroscope; , Indicates the total number of sampling moments; For the Axis accelerometer The output value at each moment; and Respectively The mean and standard deviation of the output values ​​of the gyro; and Respectively The mean and standard deviation of the output values ​​of the axis accelerometer.

[0098] (2-2) According to the mean and standard deviation, the mathematical model of the virtual gyroscope and virtual accelerometer is constructed, and the virtual output value is generated:

[0099] ;

[0100] ;

[0101] In the formula, , is the preset noise amplification factor; The standard deviation is Random noise; The standard deviation is Random noise; For the Axis gyro The virtual output value at a moment, For the Axis accelerometer The virtual output value at a certain moment.

[0102] Step 3: The strapdown inertial navigation system uses the virtual output values ​​of the gyroscope and accelerometer to perform inertial navigation solution, including the update of attitude matrix, velocity and position.

[0103] (3-1) Use the classic quaternion method to update the attitude matrix.

[0104] a) Calculation of equivalent angular increment.

[0105] ;

[0106] In the formula, It is the navigation solution cycle; , , It is the equivalent angular increment in the x, y and z directions during the navigation solution cycle; , , The angular increments in the x, y, and z directions of the gyroscope output during the navigation cycle are respectively, and the virtual output values ​​generated by the mathematical model of the virtual gyroscope in step 2 are Integrate to obtain; is latitude; , are the north speed and east speed in the navigation coordinate system; is the height of the strapdown inertial navigation system; is the Earth's rotation angular rate; and are the radii of the earth's meridian and meridian respectively, is the attitude matrix.

[0107] b) Update the attitude quaternion using the equivalent angle increment and normalize it.

[0108] ;

[0109] ;

[0110] ;

[0111] ;

[0112] In the formula, are the attitude quaternions of the strapdown inertial navigation system at time k and time k+1 respectively; and are the components of the attitude quaternion before and after normalization respectively; is the equivalent angular increment , , Model; The equivalent angular increment , , Constructed matrix; for The identity matrix of .

[0113] c) Update calculation of the attitude matrix.

[0114] ;

[0115] ;

[0116] In the formula, , , , They are the attitude quaternions at time k+1 respectively The four components of is the attitude matrix.

[0117] (3-2) Speed ​​update.

[0118] ;

[0119] ;

[0120] In the formula, For a navigation cycle The velocity increment of the strapdown inertial navigation system in the navigation coordinate system; The virtual output value generated by the mathematical model of the virtual accelerometer in step 2 Projection in the navigation coordinate system; is the projection of the Earth's rotation angular rate in the navigation coordinate system; The angular rate of rotation of the navigation coordinate system caused by the motion of the aircraft; is the speed of the strapdown inertial navigation system at time k-1; is the projection of the gravity acceleration vector in the navigation coordinate system; is the speed of the strapdown inertial navigation system at the current time k, which is decomposed into the navigation coordinate system to obtain its three-dimensional speed in three directions.

[0121] (3-3) Update of position.

[0122] ;

[0123] ;

[0124] ;

[0125] In the formula, , are the latitudes of the strapdown inertial navigation system at the current time k and time k-1 respectively; , are the longitudes of the strapdown inertial navigation system at the current time k and time k-1 respectively; , are the altitudes of the strapdown inertial navigation system at the current time k and time k-1 respectively; It is the navigation solution cycle; , , are the north, east and celestial velocities of the strapdown inertial navigation system at the current time k in the navigation coordinate system; , , are the north, east and celestial velocities of the strapdown inertial navigation system at time k-1 in the navigation coordinate system, , They represent the meridian radius and the meridian radius respectively. Figure 3 shown.

[0126] Step 4, using the Kalman filter to perform fine alignment, and using the fine alignment result to perform fine correction on the attitude matrix; the finely corrected attitude matrix and the position and velocity are used for subsequent inertial navigation of the strapdown inertial navigation system.

[0127] (4-1) Based on the error equation of the strapdown inertial navigation system, the state equation and measurement equation of the precise alignment process are established:

[0128] ;

[0129] ;

[0130] The dot above the parameter indicates the first-order derivative of the parameter. is the state variable, is the measured variable, is the state transfer matrix, and are system noise and measurement noise respectively; is the measurement matrix, The noise driven array.

[0131] ;

[0132] ;

[0133] in, It represents the estimated values ​​of misalignment angles in the east, north and sky directions in the navigation coordinate system. It indicates the velocity error in the east, north and sky directions in the navigation coordinate system. Indicates the longitude error, latitude error and altitude error in the position error. is the gyro constant drift error in the x, y, and z directions in the airborne coordinate system, is the constant zero bias error of the accelerometer in the x, y, and z directions in the airborne coordinate system.

[0134] for dimensional state transfer matrix, which can be written as:

[0135] ;

[0136] in, express The zero matrix of is the attitude matrix.

[0137] ;

[0138] In the formula, , are the projection components of the earth's rotation angular velocity vector in the celestial direction and the northern direction respectively; is the radius of the Earth; is latitude; , It is the projection component of the three-axis specific force of the triaxial accelerometer in the east, north and sky directions.

[0139] (4-2) Construct the recursive equation of the discrete Kalman filter, and perform iterative Kalman filter operation through the recursive equation until the operation reaches the specified time, and obtain the three misalignment angle estimates after precise alignment .

[0140] (4-3) Using the estimated value of the misalignment angle Attitude matrix of strapdown inertial navigation system Correction is made and the corrected attitude matrix is ​​used for inertial navigation, thereby performing combined navigation of Kalman filtering and inertial navigation.

[0141] Pose Matrix The correction method is:

[0142] ;

[0143] ;

[0144] in, To use the misalignment angle estimate The constructed skew-symmetric matrix; is the corrected attitude matrix; is the identity matrix; is the current posture matrix.

[0145] The above technical solution of the present invention can construct a virtual gyroscope and a virtual accelerometer on the basis of coarse alignment, and use the output values ​​of the virtual gyroscope and the virtual accelerometer for fine alignment through the powerful computing power of the onboard computer, thereby greatly shortening the fine alignment time and improving the alignment accuracy.

[0146] In order to verify the effect of the present invention relative to the traditional initial alignment, a medium-precision strapdown inertial navigation device is used, whose gyro zero bias stability is about 0.03° / h, and accelerometer zero bias stability is about 0.2mg; after power-on, the output values ​​of the gyro and accelerometer are collected in real time at 5ms intervals for a total of 200s of data; in the traditional initial alignment scheme, the first 20s of data are used for coarse alignment of the inertial system, and the last 180s of data are used for fine alignment; in the scheme of the present invention, the first 20s of data are used for inertial coarse alignment and a virtual gyro and accelerometer model is constructed, and its output is used for an equivalent 180s fine alignment. The fine alignment process curves of the two schemes are shown as follows. Figures 4 to 6 As shown; it can be seen from the figure that the alignment accuracy of the two schemes is equivalent, and the actual operation time of the precise alignment of the present invention is about 8s, which has a significant effect in shortening the time.

[0147] It is worth noting that: 1) The calculation scheme of the present invention can significantly shorten the precision alignment calculation time by shortening the navigation solution cycle, shortening the Kalman filter cycle, and improving the computing power of the onboard computer; while the traditional initial alignment scheme is restricted by the sampling time, and the alignment time is basically fixed. 2) In actual application, if the gyroscope and accelerometer have a significant startup process or are significantly disturbed during the alignment process, this scheme will cause the mean value of the gyroscope and accelerometer to deviate from the true value due to the short sampling time, resulting in a decrease in alignment accuracy.

[0148] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A fast alignment method based on a virtual gyroscope and an accelerometer, characterized in that: include: The strapdown inertial navigation system performs rough alignment of the aircraft in the inertial coordinate system according to the bound initial position information of the aircraft, and constructs the initial attitude matrix of the strapdown inertial navigation system; Constructing a mathematical model of a virtual gyroscope and a virtual accelerometer, and using the collected output values ​​of the gyroscope and the accelerometer to obtain virtual output values ​​of the gyroscope and the accelerometer through the mathematical model; The strapdown inertial navigation system uses the virtual output values ​​of the gyroscope and accelerometer to perform inertial navigation solutions, including the update of attitude matrix, velocity and position; A Kalman filter is used for fine alignment, and the attitude matrix is ​​finely corrected based on the fine alignment result; the finely corrected attitude matrix and the position and velocity are used for subsequent inertial navigation of the strapdown inertial navigation system.

2. The rapid alignment method based on virtual gyroscope and accelerometer according to claim 1, characterized in that: The rough alignment in the inertial coordinate system of the aircraft is performed to construct the initial attitude matrix of the strapdown inertial navigation system, including: The attitude matrix is ​​obtained by the direction cosine matrix between the geocentric inertial coordinate system and the navigation coordinate system. , the direction cosine matrix between the solidification inertial coordinate system and the aircraft inertial coordinate system , the direction cosine matrix between the geocentric inertial coordinate system and the solidification inertial coordinate system Multiply them together to get: for , decompose it into the direction cosine matrix between the earth coordinate system and the navigation coordinate system , the direction cosine matrix between the geocentric inertial coordinate system and the earth coordinate system The multiplication form is obtained based on the longitude, latitude and time interval of the strapdown inertial navigation system; for , determined by solving the direction cosine matrix differential equation using the gyroscope output; for , obtained by using the projection of the velocity vector in the geocentric inertial coordinate system and the solidification inertial coordinate system.

3. The rapid alignment method based on virtual gyroscope and accelerometer according to claim 2, characterized in that: Said for , obtained by using the projection of the velocity vector in the geocentric inertial coordinate system and the solidification inertial coordinate system, including: First determine the projection of gravity acceleration in the geocentric inertial coordinate system , and then in the time period between the current time and the initial time Integrate to obtain the relationship between the aircraft speed and time in the geocentric inertial coordinate system ; Using the output value of the accelerometer in the inertial coordinate system of the aircraft , get the current accelerometer velocity value ; According to the method of orthogonalization of attitude matrix, at different moments , The relationship between aircraft speed and time , , and the corresponding accelerometer velocity value , Obtain .

4. The rapid alignment method based on virtual gyroscope and accelerometer according to claim 1, characterized in that: The method of constructing a mathematical model of a virtual gyroscope and a virtual accelerometer, using the collected output values ​​of the gyroscope and the accelerometer, and obtaining the virtual output values ​​of the gyroscope and the accelerometer through the mathematical model comprises: First, based on the output values ​​of the gyroscope and accelerometer collected over a period of time, the mean and standard deviation are calculated as follows: ， ； ， ； In the formula, For the Axis gyro The output value at the moment, ; are the three axes of the gyroscope; , Indicates the total number of sampling moments; For the Axis accelerometer The output value at each moment; and Respectively The mean and standard deviation of the output values ​​of the gyro; and Respectively The mean and standard deviation of the output values ​​of the axis accelerometer; The mathematical models of the virtual gyroscope and virtual accelerometer are constructed according to the mean and standard deviation, and the virtual output values ​​are generated: ； ； In the formula, , is the preset noise amplification factor; The standard deviation is Random noise; The standard deviation is Random noise; For the Axis gyro The virtual output value at a moment, For the Axis accelerometer The virtual output value at a certain moment.

5. The rapid alignment method based on virtual gyroscope and accelerometer according to claim 1, characterized in that: The strapdown inertial navigation system uses virtual output values ​​of a gyroscope and an accelerometer to perform inertial navigation solution, wherein a quaternion method is used when performing attitude matrix update calculation, firstly, based on the angular increments in three directions within a navigation cycle output by the gyroscope, equivalent angular increments in three directions are determined; then, the attitude quaternion is updated and normalized using the equivalent angular increments, and the attitude matrix is ​​updated using the normalized quaternion.

6. The rapid alignment method based on virtual gyroscope and accelerometer according to claim 1, characterized in that: The strapdown inertial navigation system uses the virtual output values ​​of the gyroscope and accelerometer to perform inertial navigation solution, wherein the speed update method is: ； ； In the formula, For a navigation cycle The velocity increment of the strapdown inertial navigation system in the navigation coordinate system; Virtual output values ​​generated by the mathematical model of the virtual accelerometer Projection in the navigation coordinate system; is the projection of the Earth's rotation angular rate in the navigation coordinate system; The angular rate of rotation of the navigation coordinate system caused by the motion of the aircraft; is the speed of the strapdown inertial navigation system at time k-1; is the projection of the gravity acceleration vector in the navigation coordinate system; is the speed of the strapdown inertial navigation system at the current moment k.

7. The rapid alignment method based on virtual gyroscope and accelerometer according to claim 1, characterized in that: The strapdown inertial navigation system uses the virtual output values ​​of the gyroscope and accelerometer to perform inertial navigation solution, wherein the position update method is: ； ； ； In the formula, , are the latitudes of the strapdown inertial navigation system at the current time k and time k-1 respectively; , are the longitudes of the strapdown inertial navigation system at the current time k and time k-1 respectively; , are the altitudes of the strapdown inertial navigation system at the current time k and time k-1 respectively; It is the navigation solution cycle; , , are the north, east and celestial velocities of the strapdown inertial navigation system at the current time k in the navigation coordinate system; , , are the north, east and celestial velocities of the strapdown inertial navigation system at time k-1 in the navigation coordinate system, , They represent the meridian radius and the meridian radius respectively.

8. The rapid alignment method based on virtual gyroscope and accelerometer according to claim 1, characterized in that: The method of using a Kalman filter to perform fine alignment and finely correcting the attitude matrix based on the fine alignment result includes: According to the error equation of strapdown inertial navigation system, the state equation and measurement equation of the precise alignment process are established; Construct a recursive equation of a discrete Kalman filter, perform iterative Kalman filter operations through the recursive equation until the specified time is reached, and obtain three misalignment angle estimation values ​​after precise alignment; The attitude matrix of the strapdown inertial navigation system is corrected using the estimated value of the misalignment angle, and the corrected attitude matrix is ​​used for inertial navigation.

9. The rapid alignment method based on virtual gyroscope and accelerometer according to claim 8, characterized in that: The state equation and measurement equation of the precise alignment process are expressed as: ； ； The dot above the parameter indicates the first-order derivative of the parameter. is the state variable, is the measured variable, is the state transfer matrix, and are system noise and measurement noise respectively; is the measurement matrix, It is a noise driven array; ； ； in, It represents the estimated values ​​of misalignment angles in the east, north and sky directions in the navigation coordinate system. It indicates the velocity error in the east, north and sky directions in the navigation coordinate system. Indicates the longitude error, latitude error and altitude error in the position error. is the gyro constant drift error in the x, y, and z directions in the airborne coordinate system, is the constant zero bias error of the accelerometer in the x, y, and z directions in the airborne coordinate system.

10. A terminal device comprising a processor, a memory and a computer program stored in the memory; characterized in that: When the processor executes the computer program, the fast alignment method based on the virtual gyroscope and accelerometer according to any one of claims 1 to 9 is implemented.

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