A Method for Quick Alignment and In-air Correction during Emergency Launch

Abstract

The present invention discloses a method for rapid alignment and in-air correction during emergency launch, including: during the ground parsing and rough alignment stage, the strapdown inertial navigation system performs parsing and rough alignment according to the already bound launch position coordinates and flight target coordinates, determines the initial horizontal attitude angle and the initial azimuth angle, and calculates the initial attitude matrix for inertial navigation; during the in-air correction stage, the strapdown inertial navigation system performs inertial navigation solution; when the aircraft is in the ascending section of the flight path and the satellite navigation information is valid, the strapdown inertial navigation system is roughly corrected according to the satellite navigation information and fine alignment is performed through a Kalman filter for a period of time, and the attitude matrix is corrected using the fine alignment result, thereby realizing integrated navigation; during the accuracy verification and secondary correction stage, the accuracy of the inertial system is verified during the flight of the aircraft. If the accuracy does not meet the requirements, the strapdown inertial navigation system is secondarily corrected.

Description

Technical Field

[0001] The present invention relates to the field of strapdown inertial technology, and particularly to a method for rapid alignment and in-air correction during emergency launch, which is applicable to the rapid alignment of a strapdown inertial navigation system on a rocket-propelled aircraft before launch. Background Art

[0002] At present, using a strapdown inertial navigation system for attitude control and route correction of a rocket-propelled aircraft can effectively increase its range and significantly improve its landing accuracy, becoming the main development trend of rocket-propelled aircraft.

[0003] The strapdown inertial navigation system needs to perform initial alignment during operation: determine the attitude matrix at the initial moment to make the mathematical platform coordinate system coincide with the navigation coordinate system. Initial alignment can be divided into coarse alignment and fine alignment according to stages; it can be divided into static base alignment and moving base alignment according to the motion state of the base; it can be divided into autonomous alignment and non-autonomous alignment according to the dependence on external information; the accuracy and time of initial alignment are its two most important technical indicators.

[0004] The strapdown inertial navigation system on a rocket-propelled aircraft usually adopts a static base alignment scheme. The alignment process is to first perform coarse alignment, and then use Kalman filtering for fine alignment. The alignment time usually takes more than 150 s. With the requirement of shorter launch response time, the initial alignment time may be only a few seconds in the case of emergency launch. The traditional strapdown inertial navigation initial alignment scheme cannot meet the requirements of the system; moreover, due to the short preparation time, it may not even provide accurate azimuth information for the inertial navigation system. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for rapid alignment and in-air correction during emergency launch to overcome the problems of long alignment time and difficulty in meeting the requirements of emergency launch existing in the existing alignment methods.

[0006] To achieve the above task, the present invention adopts the following technical solutions:

[0007] A method for rapid alignment and in-air correction during emergency launch includes:

[0008] In the ground analytical coarse alignment stage, the strapdown inertial navigation system performs analytical coarse alignment according to the bound launch position coordinates and flight target coordinates, determines the initial horizontal attitude angle and initial azimuth angle, and calculates the initial attitude matrix for inertial navigation;

[0009] In the in-air correction stage, the strapdown inertial navigation system performs inertial navigation solution; when the aircraft is in the ascending section of the route and the satellite navigation information is valid, the strapdown inertial navigation system is roughly corrected according to the satellite navigation information and fine alignment is performed through a Kalman filter for a period of time, and the attitude matrix is corrected using the fine alignment result, thereby realizing integrated navigation;

[0010] In the accuracy verification and secondary correction stage, the accuracy of the strapdown inertial navigation system is verified during the flight of the aircraft. If the accuracy does not meet the requirements, the strapdown inertial navigation system is secondarily corrected.

[0011] Furthermore, the strapdown inertial navigation system performs analytical coarse alignment based on the loaded launch position coordinates and flight target coordinates, determines the initial horizontal attitude angle and the initial azimuth angle, and calculates the initial attitude matrix for inertial navigation, including:

[0012] Load the launch position coordinates and the flight target coordinates into the strapdown inertial navigation system, where both the launch position coordinates and the flight target coordinates include longitude and latitude;

[0013] Collect the outputs of the accelerometer in three directions within the first preset time, take the mean of each output respectively to obtain the output components in three directions, and determine the initial horizontal attitude angle, including the initial pitch angle and the initial roll angle, by using the relationship between the output components in three directions;

[0014] Determine the initial azimuth angle by using the longitudes and latitudes in the launch position coordinates and the flight target coordinates;

[0015] Determine the initial attitude matrix based on the initial azimuth angle, the initial pitch angle, and the initial roll angle.

[0016] Furthermore, the strapdown inertial navigation system performs inertial navigation solution, including the update of the attitude matrix;

[0017] When updating the attitude matrix, the quaternion method is adopted. First, based on the angular increments in three directions within the navigation period output by the gyroscope, determine the equivalent angular increments in three directions; then use the equivalent angular increments to update and normalize the attitude quaternion, and use the normalized quaternion to update the attitude matrix.

[0018] Furthermore, the strapdown inertial navigation system performs inertial navigation solution, including the update of the three-dimensional velocity and the update of the three-dimensional position;

[0019] When updating the three-dimensional velocity, use the projection of the acceleration vector output by the accelerometer in the navigation coordinate system, the velocity of the strapdown inertial navigation system at the previous moment, and the projection of the gravitational acceleration vector in the navigation coordinate system to calculate the velocity increment of the strapdown inertial navigation system within one navigation period in the navigation coordinate system; based on the velocity increment and the velocity of the strapdown inertial navigation system at the previous moment, determine the three-dimensional velocity of the strapdown inertial navigation system at the current moment;

[0020] When updating the three-dimensional position, the latitude, longitude, and altitude of the strapdown inertial navigation system at the previous moment are used, combined with the velocities of the strapdown inertial navigation system at the current moment and the previous moment in the navigation coordinate system, to calculate the longitude, latitude, and altitude at the current moment, thereby obtaining the three-dimensional position.

[0021] Further, the rough correction of the strapdown inertial navigation system according to the satellite navigation information includes:

[0022] After the satellite navigation information is valid, the three-dimensional velocities and three-dimensional positions in the eastward, northward, and upward directions in the navigation coordinate system provided by the satellite navigation information are directly assigned to correct the three-dimensional velocities and three-dimensional positions during the inertial navigation solution of the strapdown inertial navigation system; at the same time, the track angle of the aircraft is calculated using the three-dimensional velocity, and the initial azimuth angle is corrected by assigning the track angle, thereby performing a rough correction on the inertial navigation.

[0023] Further, the fine alignment through the Kalman filter for a period of time includes:

[0024] According to the error equation of the strapdown inertial navigation system, the state equation and measurement equation for the fine alignment process are established;

[0025] The recurrence equation of the discrete Kalman filter is constructed, and iterative Kalman filtering operations are performed through the recurrence equation until the specified second preset time is reached, obtaining the estimated values of the three misalignment angles in the eastward, northward, and upward directions after fine alignment.

[0026] Further, the state equation and measurement equation for the fine alignment process are expressed as:

[0027] ;

[0028] ;

[0029] Among them, the dot above the parameter indicates the first derivative of the parameter, is the state variable, is the measurement variable, is the state transition matrix, and are the system noise and measurement noise respectively; is the measurement matrix, is the noise driving matrix;

[0030] ;

[0031] ;

[0032] Among them, represents the estimated values of the three misalignment angles in the eastward, northward, and upward directions, It represents the velocity errors in the east, north, and up directions in the navigation coordinate system. It represents the longitude error, latitude error, and altitude error. They are the gyro constant drift errors in the x, y, and z directions in the airborne coordinate system. They are the accelerometer constant zero bias errors in the x, y, and z directions in the airborne coordinate system.

[0033] Furthermore, the method of using the fine alignment result to correct the attitude matrix to achieve integrated navigation includes:

[0034] Construct a skew-symmetric matrix using the three misalignment angle estimation values in the east, north, and up directions after fine alignment.

[0035] Use the skew-symmetric matrix and the identity matrix to correct the current attitude matrix to obtain the corrected attitude matrix, and use the corrected attitude matrix for inertial navigation, thereby performing integrated navigation of Kalman filtering and inertial navigation.

[0036] A terminal device includes a processor, a memory, and a computer program stored in the memory; when the processor executes the computer program, it implements the method for rapid alignment and in-air correction during emergency launch.

[0037] A computer-readable storage medium stores a computer program; when the computer program is executed by a processor, it implements the method for rapid alignment and in-air correction during emergency launch.

[0038] Compared with the prior art, the present invention has the following technical features:

[0039] 1. In view of the limitation that the alignment time is only a few seconds in the case of emergency launch of a rocket-propelled aircraft, the present invention adopts an analytical coarse alignment method to obtain relatively accurate initial pitch angle, initial roll angle, and rough initial azimuth angle; it provides the attitude control information required for the rocket-propelled aircraft during the active flight segment when satellite navigation and positioning information is missing for the airborne computer; after the satellite positioning information becomes valid, through in-air coarse correction and fine alignment, and according to the fine alignment result, correct the azimuth angle, velocity, and position information of the inertial navigation system to improve the accuracy of the inertial navigation system, and utilize the maneuver of the rocket-propelled aircraft to improve the observability of the system; in the later flight stage, verify the accuracy of the strapdown inertial navigation system and perform secondary correction as needed. The present invention provides a complete alignment scheme under emergency launch conditions, overcoming the shortcomings of traditional initial alignment: transfer alignment requires the information of the master inertial navigation and a certain time of maneuver; self-alignment requires high-precision inertial devices and a long alignment time.

[0040] 2. The present invention utilizes the maneuver of the rocket - propelled aircraft during in - flight route correction for in - air alignment, which improves the observability of the azimuth misalignment angle and achieves a relatively high alignment accuracy, without the need for the rocket - propelled aircraft to perform additional dedicated maneuvers at the cost of energy. Brief Description of the Drawings

[0041] Figure 1 It is a schematic flowchart of the method in an embodiment of the present invention;

[0042] Figure 2 It is a working principle diagram of the solution of inertial navigation in an embodiment of the present invention;

[0043] Figure 3 It is a misalignment angle estimation curve in an embodiment of the present invention. Detailed Embodiment

[0044] The present invention provides a method for rapid alignment and in - air correction during emergency launch. Refer to Figure 1 , which includes a ground analytical rough alignment stage, an in - air correction stage, and an accuracy verification and secondary correction stage;

[0045] In the ground analytical rough alignment stage, the strap - down inertial navigation system performs analytical rough alignment based on the loaded launch position coordinates and flight target coordinates, determines the initial horizontal attitude angle and initial azimuth angle, and calculates the initial attitude matrix for inertial navigation;

[0046] In the in - air correction stage, the strap - down inertial navigation system performs the solution of inertial navigation; when the aircraft is in the ascending section of the route and the satellite navigation information is valid, the strap - down inertial navigation system is roughly corrected according to the satellite navigation information and finely aligned through a Kalman filter for a period of time, and the attitude matrix is corrected using the fine alignment result, thereby realizing integrated navigation;

[0047] In the accuracy verification and secondary correction stage, the accuracy of the strap - down inertial navigation system is verified during the flight of the aircraft. If the accuracy does not meet the requirements, the strap - down inertial navigation system is subjected to secondary correction.

[0048] The following further elaborates on the specific implementation process of the present invention with reference to the accompanying drawings.

[0049] I. Ground Analytical Rough Alignment Stage.

[0050] Step 1, the strap - down inertial navigation system carried on the aircraft is in a stationary state and powers on for preparation.

[0051] Step 2, load the launch position coordinates (longitude , latitude and altitude ) and flight target coordinates (longitude , latitude and height )

[0052] Step 3, the strapdown inertial navigation system performs analytic coarse alignment: collect the outputs of the accelerometer in the x, y, and z directions within the first preset time and take their respective means to obtain , , Substitute into the following formula, then the initial horizontal attitude angles, including the initial pitch angle and the initial roll angle are:[[]]

[0053] ;

[0054] ;

[0055] The initial azimuth angle can be calculated from the launch position coordinates and the flight target coordinates using the following formula, or can be roughly measured by geomagnetism or other sensors:[[]]

[0056] ;

[0057] Then substitute the initial azimuth angle , the initial pitch angle and the initial roll angle into the azimuth angle parameter , the pitch angle parameter , the roll angle parameter in the following formula to calculate the initial attitude matrix :[[]]

[0058] ;

[0059] Among them, represents the aircraft's body coordinate system, taking the right-front-up coordinate system, with the coordinate origin located at the centroid of the strapdown inertial navigation system; n is the navigation coordinate system, taking the northeast-up coordinate system ENU, with the coordinate origin located at the centroid of the strapdown inertial navigation system; is the attitude matrix between the body coordinate system and the navigation coordinate system, which is the variable to be determined for the alignment of the strapdown inertial navigation system; the initial attitude matrix is used for the update iteration in the subsequent inertial navigation process.

[0060] II. In-air correction stage.

[0061] Step 4, the strapdown inertial navigation system performs inertial navigation calculation; during the launch process of the aircraft, the initial attitude matrix is updated, and information such as the three-axis angular velocity, three-axis acceleration, initial horizontal attitude angle, initial azimuth angle, three-dimensional velocity, and three-dimensional position is sent to the aircraft's on-board computer for the information required for inertial navigation, so as to maintain the attitude stability of the aircraft after launch.

[0062] Among them, in the initial horizontal attitude angle, the initial pitch angle and the initial roll angle are relatively accurate because they are directly calculated from the output of the accelerometer; while the initial azimuth angle has a large error, so it is a rough alignment stage; the three-dimensional velocity and three-dimensional position are given by the inertial navigation calculation, and the inertial navigation calculation process is as follows:

[0063] Step 4.1, use the classical quaternion method to update the attitude matrix.

[0064] a) Equivalent angle increment calculation.

[0065] ;

[0066] In the formula, is the navigation solution period; , , are the equivalent angle increments in the x, y, and z directions within the navigation solution period; , , are the angle increments in the x, y, and z directions within the navigation period output by the gyroscope, obtained by integrating the angular velocity; is the latitude of the location where the strapdown inertial navigation system is located; , are the northward velocity and eastward velocity in the navigation coordinate system; is the altitude of the location where the strapdown inertial navigation system is located; is the angular velocity of the Earth's rotation; and are the radius of the Earth's prime vertical and the radius of the meridian respectively.

[0067] b) Use the equivalent angle increment to update and normalize the attitude quaternion.

[0068] ;

[0069] ;

[0070] ;

[0071] ;

[0072] In the formula, are the attitude quaternions of the strapdown inertial navigation system at time k and k+1 respectively; and are the components of the attitude quaternion before and after normalization respectively; is the equivalent angular increment 、 、 is the modulus of; is from the equivalent angular increment 、 、 constructed matrix; is identity matrix of.

[0073] c) Update of the attitude matrix.

[0074] ;

[0075] ;

[0076] In the formula, 、 、 、 are the four components of the attitude quaternion at time k+1 respectively; is the attitude matrix.

[0077] Step 4.2, Update of the three-dimensional velocity.

[0078] ;

[0079] ;

[0080] In the formula, is the velocity increment of the strapdown inertial navigation system in the navigation coordinate system within a navigation period ; is the projection of the acceleration vector output by the accelerometer in the navigation coordinate system; is the projection of the earth's angular rotation rate in the navigation coordinate system; is the angular rotation rate of the navigation coordinate system caused by the movement of the aircraft; is the velocity of the strapdown inertial navigation system at time k-1; is the projection of the gravitational acceleration vector in the navigation coordinate system; is the velocity of the strapdown inertial navigation system at the current time k. Its three-dimensional velocity in three directions is obtained by decomposing it in the navigation coordinate system.

[0081] Step 4.3, Update of the three-dimensional position.

[0082] ;

[0083] ;

[0084] ;

[0085] wherein, and are the latitudes of the strapdown inertial navigation system at the current time k and the time k-1 respectively; and are the longitudes of the strapdown inertial navigation system at the current time k and the time k-1 respectively; and are the altitudes of the strapdown inertial navigation system at the current time k and the time k-1 respectively; is the navigation solution period; and and are the northward, eastward, and upward velocities of the strapdown inertial navigation system in the navigation coordinate system at the current time k respectively; and and are the northward, eastward, and upward velocities of the strapdown inertial navigation system in the navigation coordinate system at the time k-1 respectively, and represent the radius of the meridian and the radius of the prime vertical respectively.

[0086] The schematic diagram of inertial navigation solution is shown in Appendix Figure 2 as follows.

[0087] Step 5, coarse in-air correction: When the aircraft is in the ascending stage of the flight path after launch, the satellite receiver continuously locates the aircraft. When the satellite navigation information is valid, the three-dimensional velocities and and in the eastward, northward, and upward directions in the navigation coordinate system provided by the satellite navigation information, longitude, latitude, and altitude and are directly used to assign values to correct the three-dimensional velocity and three-dimensional position during the inertial navigation solution of the strapdown inertial navigation system; meanwhile, is calculated using and the course angle

[0088] .

[0089] Step 6, perform fine alignment within the second preset time using the Kalman filter, and obtain the estimated values of the misalignment angles in the eastward, northward, and upward directions It should be noted that in order to improve the observability of the misalignment angle, the aircraft needs to perform maneuvers for a certain period of time. At this time, due to the large error in the previous azimuth, there is a certain error between the flight path of the aircraft and the theoretical flight path, and the aircraft needs to perform appropriate maneuvers to correct the flight path.

[0090] Step 6.1, according to the error equation of the strapdown inertial navigation system, establish the state equation and measurement equation of the fine alignment process:

[0091] ;

[0092] ;

[0093] Among them, the dot on the parameter superscript represents the first derivative of the parameter, is the state variable, is the measurement variable, is the state transition matrix, and are the system noise and measurement noise respectively; is the measurement matrix, is the noise driving matrix.

[0094] ;

[0095] Among them, represents the estimated values of the three misalignment angles in the east, north, and vertical directions, represents the velocity errors in the east, north, and vertical directions in the navigation coordinate system, represents the longitude error, latitude error, and altitude error, is the constant drift error of the gyroscope in the x, y, and z directions in the aircraft coordinate system, is the constant zero bias error of the accelerometer in the x, y, and z directions in the aircraft coordinate system.

[0096] ;

[0097] Among them, , , represent the three-dimensional velocities in the east, north, and vertical directions in the navigation coordinate system provided by the satellite navigation information, , , represent the longitude, latitude, and altitude provided by the satellite navigation information, , , are the three-dimensional velocities in the east, north, and vertical directions calculated by the strapdown inertial navigation system, , , The longitude, latitude, and altitude calculated by the strapdown inertial navigation system.

[0098] For the dimensional state transition matrix, it can be written as:

[0099] ;

[0100] where represents the zero matrix of and

[0101] ;

[0102] In the formula, , are the projection components of the earth's angular velocity vector in the celestial and north directions respectively; is the earth's radius; is the latitude of the location where the strapdown inertial navigation system is located; , are the projection components of the specific force of the three axes of the accelerometer in the east, north, and celestial directions; is the attitude matrix.

[0103] Step 6.2, construct the recurrence equation of the discrete Kalman filter, and perform iterative Kalman filtering operations through the recurrence equation until the operation reaches the specified second preset time , and obtain the estimated values of the three misalignment angles after fine alignment.

[0104] Step 7, in-air fine correction: Use the estimated misalignment angle value to correct the attitude matrix of the strapdown inertial navigation system, and use the corrected attitude matrix for inertial navigation, thereby performing combined navigation of Kalman filtering and inertial navigation.

[0105] The method for correcting the attitude matrix is as follows:

[0106] ;

[0107] ;

[0108] where is the skew-symmetric matrix constructed using the estimated misalignment angle value ; is the corrected attitude matrix; is the identity matrix; is the current attitude matrix.

[0109] It should be noted that in this stage, the correction process of the three-dimensional velocity and three-dimensional position during inertial navigation using the three-dimensional velocity and three-dimensional position information in the navigation coordinate system provided by satellite navigation information in step 5 is continuously executed.

[0110] III. Precision verification secondary correction stage.

[0111] Step 8, after the strapdown inertial navigation system is accurately corrected in the air, reset the Kalman filter and perform integrated navigation solution; during the integrated navigation process, verify the accuracy of the strapdown inertial navigation system. If the accuracy does not meet the requirements, the strapdown inertial navigation system can be secondarily corrected according to the methods in step 6 and step 7 to improve the accuracy.

[0112] To verify the effect of the present invention, the following simulation tests are carried out:

[0113] 1) Select a medium and low-precision strapdown inertial navigation system with a gyroscope zero bias of 0.5° / h and an accelerometer zero bias of 0.2mg.

[0114] 2) After power-on, perform static alignment for 3s and then transfer to inertial navigation; after rough correction in the air, the initial azimuth error is about 2°, and the initial pitch angle and initial roll angle errors are about 0.1°.

[0115] 3) From 5s to 15s during the flight, the aircraft has accelerations of 0.3g and 0.25g in the horizontal direction respectively, and flies in a uniform straight line at other times; the fine alignment time is 60s, and the alignment result is as Figure 3 shown.

[0116] From Figure 3 it can be seen that the misalignment angles in the east, north, and up directions all converge quickly. The estimated errors in the east and north directions are about 0.01°, and the estimated error of the up misalignment angle is about 0.03°, and the estimation effect is good.

[0117] It should be noted that the convergence speed of the direction misalignment angle is greatly affected by the horizontal acceleration. Therefore, in practical applications, the fine alignment time and horizontal acceleration should be reasonably arranged according to the maneuverability of the airframe and the flight time to achieve an ideal estimation effect.

[0118] 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 foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate 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 method for rapid alignment and in-air correction during emergency launch, characterized in that, Including: During the ground analytical coarse alignment phase, the strapdown inertial navigation system performs analytical coarse alignment based on the installed launch position coordinates and flight target coordinates, determines the initial horizontal attitude angles and the initial azimuth angle, and calculates the initial attitude matrix for inertial navigation, including: Installing the launch position coordinates and the flight target coordinates into the strapdown inertial navigation system, where both the launch position coordinates and the flight target coordinates include longitude and latitude; Collecting the outputs of the accelerometer in three directions within the first preset time, respectively taking their means to obtain the output components in three directions, and determining the initial horizontal attitude angles, including the initial pitch angle and the initial roll angle, by using the relationship between the output components in three directions; Determining the initial azimuth angle by using the longitudes and latitudes in the launch position coordinates and the flight target coordinates; Determining the initial attitude matrix based on the initial azimuth angle, the initial pitch angle, and the initial roll angle; During the in-air correction phase, the strapdown inertial navigation system performs inertial navigation solution; when the aircraft is in the ascending section of the flight path and the satellite navigation information is valid, the strapdown inertial navigation system is coarsely corrected according to the satellite navigation information and finely aligned through a Kalman filter for a period of time, including: establishing the state equation and the measurement equation for the fine alignment process according to the error equation of the strapdown inertial navigation system; constructing the recurrence equation of the discrete Kalman filter, and performing iterative Kalman filtering operations through the recurrence equation until the specified second preset time is reached, obtaining the estimated values of the three misalignment angles in the east, north, and vertical directions after fine alignment; and correcting the attitude matrix by using the fine alignment result, thereby realizing integrated navigation; During the accuracy verification and secondary correction phase, the accuracy of the strapdown inertial navigation system is verified during the flight of the aircraft. If the accuracy does not meet the requirements, the strapdown inertial navigation system is secondarily corrected.

2. The rapid alignment and in-air correction method during emergency launch according to claim 1, wherein The strapdown inertial navigation system performs inertial navigation solution, including the update of the attitude matrix; When updating the attitude matrix, the quaternion method is adopted. First, based on the angular increments in three directions within the navigation period output by the gyroscope, the equivalent angular increments in three directions are determined; then the attitude quaternion is updated and normalized by using the equivalent angular increments, and the attitude matrix is updated by using the normalized quaternion.

3. The rapid alignment and in-air correction method during emergency launch according to claim 1, characterized in that The strapdown inertial navigation system performs inertial navigation solution, including the update of the three-dimensional velocity and the update of the three-dimensional position; When updating the three-dimensional velocity, the projection of the acceleration vector output by the accelerometer in the navigation coordinate system, the velocity of the strapdown inertial navigation system at the previous moment, and the projection of the gravity acceleration vector in the navigation coordinate system are used to calculate the velocity increment of the strapdown inertial navigation system within the navigation coordinate system in a navigation period; Based on the velocity increment and the velocity of the strapdown inertial navigation system at the previous moment, the three-dimensional velocity of the strapdown inertial navigation system at the current moment is determined; When updating the three-dimensional position, the latitude, longitude, and altitude of the strapdown inertial navigation system at the previous moment are used, combined with the velocities of the strapdown inertial navigation system at the current moment and the previous moment in the navigation coordinate system, to calculate the longitude, latitude, and altitude at the current moment, thereby obtaining the three-dimensional position.

4. The rapid alignment and in-air correction method during emergency launch according to claim 1, characterized in that The coarse correction of the strapdown inertial navigation system according to the satellite navigation information includes: After the satellite navigation information becomes valid, the three-dimensional velocity and three-dimensional position in the eastward, northward, and upward directions in the navigation coordinate system provided in the satellite navigation information are directly assigned to correct the three-dimensional velocity and three-dimensional position during the inertial navigation solution of the strapdown inertial navigation system; at the same time, the track angle of the aircraft is calculated using the three-dimensional velocity, and the initial azimuth angle is corrected by assigning the track angle, thereby performing a rough correction on the inertial navigation.

5. The rapid alignment and in-air correction method during emergency launch according to claim 1, characterized in that, The state equation and measurement equation of the fine alignment process are expressed as: Z = HX + v; where the dot above the parameter indicates the first derivative of the parameter, X is the state variable, Z is the measurement variable, A is the state transition matrix, W and v are the system noise and measurement noise respectively; H is the measurement matrix, and G is the noise driving matrix; Z = [δV E , δV N , δV U , δλ, δL, δH]; Among them, represent the estimated values of three misalignment angles in the east, north, and sky directions, δV E , δV N , δV U represent the velocity errors in the east, north, and sky directions in the navigation coordinate system, δλ, δL, and δH represent the longitude error, latitude error, and altitude error, ε x , ε y , ε z are the constant drift errors of the gyroscopes in the x, y, and z directions in the aircraft body coordinate system, is the constant zero bias error of the accelerometers in the x, y, and z directions in the aircraft body coordinate system.

6. The rapid alignment and in-air correction method during emergency launch according to claim 1, characterized in that The correction of the attitude matrix using the fine alignment result to achieve integrated navigation includes: Constructing a skew-symmetric matrix using the three misalignment angle estimates in the eastward, northward, and upward directions after fine alignment; Correcting the current attitude matrix using the skew-symmetric matrix and the identity matrix to obtain the corrected attitude matrix, and performing inertial navigation using the corrected attitude matrix, thereby performing integrated navigation of Kalman filtering and inertial navigation.

7. 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, it implements the rapid alignment and in-air correction method during emergency launch according to any one of claims 1-6.

8. A computer-readable storage medium storing a computer program therein; characterized in that, When the computer program is executed by the processor, it implements the rapid alignment and in-air correction method during emergency launch according to any one of claims 1-6.

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