Method for precise aerial delivery and aerial fast alignment based on inertial navigation / satellite integrated navigation

Abstract

This invention discloses a method for precise airdrop and rapid in-flight alignment based on inertial navigation / satellite integrated navigation. The method includes: after the navigation device is powered on, establishing a carrier and navigation inertial coordinate system through inertial solidification; periodically acquiring angular rate and specific force data from the inertial measurement unit and position and velocity data from the satellite receiver; sequentially calculating carrier system tracking, specific force integration, navigation system tracking, and acceleration integration; and recursively solving the problem using a Rodrigues parameter multi-vector attitude determination algorithm to calculate the real-time attitude matrix, repeating this process until alignment is complete. This invention simplifies the initial alignment problem without initial values ​​for arbitrary attitudes into an unconstrained linear optimal estimation problem for Rodrigues parameters, utilizing specific force and acceleration integration as measurement information, and fully utilizing all effective data during the alignment process. It requires no initial attitude information and can rapidly complete alignment under complex dynamic base conditions such as airdrop swaying and rotation, outputting attitude results in real time, significantly improving alignment accuracy and speed.

Description

Technical Field

[0001] This invention belongs to the field of precision airdrop navigation control technology for equipment inertial navigation / satellite integrated navigation devices. It relates to a method for rapid air alignment of an inertial navigation device with arbitrary misalignment angles based on inertial navigation / satellite integrated navigation precision airdrop, and more particularly to a method for determining the short-term rapid initial attitude of the navigation device after airdrop payload is deployed and activated in the air. Background Technology

[0002] Precision airdrop systems are systems that perfectly combine modern navigation (especially inertial navigation technology), guidance and control technology, and traditional airdrop technology. They can realize functions such as airdrop trajectory planning, parachute control, atmospheric estimation, and long-distance precision delivery, greatly expanding the practical applications of airdrops. Whether or not they have inertial navigation devices and satellite navigation systems is the main feature that distinguishes modern precision airdrops from traditional airdrops, and it is also the mainstream direction of airdrop technology development.

[0003] Inertial navigation, as a real-time navigation method based on dead reckoning, is completely autonomous and has a natural advantage in combination with satellite navigation systems. However, before entering the navigation working state, the inertial navigation device first needs to determine its own initial attitude information, that is, initial alignment. The length of alignment time and accuracy represent the rapid response capability and navigation performance of the inertial navigation system.

[0004] Because the airdrop payload of the precision airdrop system is connected to the parachute by ropes, the airdrop device will sway arbitrarily in the air. After the SINS / GNSS integrated navigation system is powered on and the GNSS achieves normal positioning, it enters initial alignment. At this time, the initial attitude of the SINS may be arbitrary, and the GNSS track angle cannot be used as the coarse heading angle of the inertial navigation system. Traditional GNSS-assisted alignment methods are no longer applicable. Therefore, it is necessary to consider GNSS-assisted alignment algorithms under arbitrary misalignment angles under the condition of a moving base in the air. In addition, since the airdrop payload is in the process of returning to the airdrop target point after deployment, and the shorter the airdrop time, the better the safety and combat effectiveness of the airdrop payload can be guaranteed, the navigation system must enter navigation mode as soon as possible to maximize the accuracy of the precise airdrop landing point. Therefore, when designing the alignment algorithm, it is necessary to focus on the speed of alignment while ensuring alignment accuracy.

[0005] Chinese patent CN112099071B, published on December 18, 2020, discloses a rapid initial attitude determination device and method for a precise airdrop navigation device. This method employs a combination of satellite navigation module and inertial measurement unit (IMU) for calculation, enabling rapid calculation of the initial attitude value of the air-dropped vehicle under motion and swaying conditions. However, this method uses the TRIAD algorithm to calculate the initial attitude, which has significant technical drawbacks: First, information utilization is incomplete; attitude results cannot be output during alignment, and only a single-point attitude can be obtained at the end of alignment, hindering the control system from adjusting the vehicle's attitude in a timely manner. Second, the final result calculation and orthogonalization require matrix inversion, significantly increasing the algorithm's complexity. Third, it is susceptible to measurement noise, potentially leading to attitude determination failure under extreme conditions. Summary of the Invention

[0006] To address the problems existing in the prior art, the purpose of this invention is to provide a rapid initial alignment method for accurately airdropping an inertial navigation device equipped with a SINS / GNSS integrated navigation system. This method enables rapid and high-precision initial alignment after the inertial navigation device is powered on in the air. The core of this method is the use of a Rodrigues parameter multi-vector attitude determination recursive algorithm, which can output the attitude results of the inertial navigation device in real time, while significantly improving the alignment accuracy.

[0007] The technical solution adopted in this invention is:

[0008] The method for precise airdrop and rapid in-flight alignment based on inertial navigation / satellite integrated navigation is as follows: After the navigation device is powered on, the carrier inertial coordinate system and the navigation inertial coordinate system are established through inertial solidification. The angular rate and specific force data of the inertial measurement unit and the position and velocity data of the satellite receiver are periodically collected. The carrier system attitude tracking, specific force integration, navigation system attitude tracking and acceleration integration are calculated in sequence, and the integration is normalized. The Rodrigo parameters corresponding to the initial attitude of the inertial navigation are recursively solved through a multi-vector attitude determination recursive algorithm, and then the real-time attitude matrix is ​​calculated. The process is repeated until the alignment is completed.

[0009] The beneficial effects of this invention are: (1) The method of the present invention takes the Rodrigue parameters corresponding to the attitude matrix at the initial alignment time as the estimation target, and simplifies the initial alignment problem without initial value under any attitude into an unconstrained linear optimal estimation problem of Rodrigue parameters. (2) The method of the present invention establishes a corresponding measurement model by using the specific force integral and acceleration integral as measurement information, and gives a specific recursive process. This method makes full use of all effective data in the alignment process, thereby improving the alignment accuracy. (3) The method of the present invention has no special requirements for the installation of the precision airdrop inertial navigation device. It can be powered on in the air without initial information and can quickly complete the initial alignment under complex conditions such as shaking and rotation in the air, thereby improving the combat effectiveness and airdrop accuracy of the equipment. Attached Figure Description

[0010] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is the pitch angle estimation result curve using existing methods with an initial attitude of a small angle; Figure 3 The curve represents the roll angle estimation result using existing methods with a small initial attitude angle. Figure 4 The curve represents the heading angle estimation result using existing methods with a small initial attitude angle. Figure 5 This is the pitch angle estimation result curve using the method of this invention with an initial attitude of a small angle; Figure 6 This is the roll angle estimation result curve using the method of this invention with an initial attitude of a small angle; Figure 7 This is the curve of the heading angle estimation result using the method of this invention with an initial attitude of a small angle; Figure 8 The curve represents the pitch angle estimation result using existing methods with an initial attitude of a large angle. Figure 9 The curve represents the roll angle estimation result using existing methods with a large initial angle. Figure 10 The curve represents the heading angle estimation result using existing methods with an initial attitude at a large angle. Figure 11 This is the pitch angle estimation result curve using the method of this invention with an initial attitude of a large angle; Figure 12 This is the roll angle estimation result curve using the method of this invention with an initial attitude of a large angle; Figure 13 The curve represents the heading angle estimation result using the method of this invention with an initial attitude of a large angle. Detailed Implementation

[0011] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0012] This invention relates to a method for rapid aerial alignment of a precision airdrop device based on inertial navigation / satellite integrated navigation. It utilizes only the angular velocity and force information output by the inertial navigation system and the velocity and position information output by the satellite receiver to achieve rapid aerial alignment of the precision airdrop navigation device. The process is as follows: Figure 1As shown, please follow these steps: Step 1: Power on the navigation device in the air. After the GNSS positioning is normal, start the alignment mode and record the initial geographical location latitude of the carrier at the start of alignment. ,longitude Initial velocity And establish the carrier's inertial coordinate system based on the start time. Navigation inertial coordinate system Specifically, the relevant coordinate systems involved in the alignment process are defined as follows: —The coordinate system of the precision airdrop inertial navigation device carrier is determined by the “right-front-up” direction of the inertial measurement unit (IMU); —The carrier's inertial coordinate system, at the initial moment of alignment, is artificially set to the carrier coordinate system. By "freezing" in inertial space, the carrier's inertial coordinate system is obtained. ; —Navigation coordinate system, the navigation coordinate system is selected as the "East-North-Sky" geographic coordinate system; —The navigation inertial coordinate system, at the initial moment of alignment, is manually adjusted. By "freezing" in inertial space, the navigation inertial coordinate system is obtained. .

[0013] Step 2, Inertial Measurement Unit Data Acquisition: in periodic... Angular rates measured by a triaxial gyroscope and a triaxial accelerometer were collected. Comparison data ,in , , and , , These are the triaxial angular velocity and specific force, respectively. Indicates the carrier coordinate system. These represent the three axes of the load system: right, front, and top.

[0014] Step 3, Satellite Receiver Data Acquisition: (periodic) Read and analyze satellite receiver information to obtain real-time data from the carrier. time( , (Positive integers) position and velocity, where position includes geographic latitude. ,longitude and height The speed includes the eastward speed in the local geographic coordinate system. Northbound speed And the speed of the sky ,in for Integer multiples of.

[0015] Step 4, Carrier system attitude matrix and Time comparison integral Calculation: Among them, the attitude matrix The attitude differential equation is: (1) In the formula, Indicates the gyroscope output angular velocity The cross product of the antisymmetric matrix, Represents the coordinate system of the inertial navigation vehicle to the carrier inertial coordinate system The attitude transformation matrix, This represents a third-order identity matrix.

[0016] The above equation is solved using the mature quaternion algorithm for strapdown inertial navigation.

[0017] Time comparison integral Calculation: (2) The calculation of the above formula can be referenced from the single-sample algorithm for velocity calculation in strapdown inertial navigation systems, that is: (3) in, , .

[0018] Step 5, Navigation system attitude matrix and acceleration integral Calculation: Among them, the attitude matrix The attitude differential equation is: (4) In the formula, Represents the real-time navigation coordinate system To navigation inertial coordinate system The attitude transformation matrix can be calculated by parsing the position information output by the satellite receiver: (5) in, , They represent The latitude and longitude at any given time are obtained from the satellite receiver. Here, represents the longitude value rotated relative to the inertial frame during the carrier alignment process. This represents the Earth's rotational angular rate.

[0019] Comparative integral calculate: (6) The above formula is equivalent to: (7) in, To align the carrier velocity at the start time; For satellite receiver The speed output at any given moment, i.e. ; and Received by satellite The location information at a given time is calculated, i.e. , , The calculation is then performed using the Earth's gravity model: .

[0020] The discrete update method of equation (7) is as follows: (8) In the formula: (9) (10) (11) Step 6: Integral calculated in Steps 4 and 5 and Normalization is performed to eliminate the difference in the dimensions of integrals and improve the accuracy of recursive solutions; The normalization process is as follows: (12) (13) Step 7: Complete the recursive process for linear optimal estimation of multi-vector attitude determination based on Rodrigue parameters; the specific recursive process is as follows: (1) When At that time, perform recursive initialization: , , ; (2) When When recursively, proceed as follows: (14) (15) (16) (17) (18) (19) (3) ; (4) When At that time, obtained by recursive update and Solve for the Rodrigues parameters : (20) Step 8: Determine if If the condition is met, proceed to step 9; otherwise, return to step 2. Step 9: Based on the calculation results of Step 7 Calculate the attitude matrix : (twenty one) Step 10: Calculate the real-time attitude matrix ; Combined with the calculation in step 4 The calculation in step 5 The calculation in step 9 It can be calculated: (twenty two) Step 11: Determine if alignment is complete. If not, return to Step 2 to continue; if complete, proceed with the steps calculated in Step 10. This is the final alignment result, and the alignment is now complete.

[0021] The following simulation experiment further illustrates the specific implementation methods and effects of the present invention.

[0022] Example 1: Simulation conditions: The total simulation duration is 10 seconds. The trajectory is set according to the precise airdrop hovering homing method, with a hovering turning radius of 1000m and a hovering speed of 180m / s. The gyroscope constant drift in the precise airdrop inertial navigation system is 1° / h, and the random walk noise is 0.1° / h. Accelerometer zero point is 200ug, random noise is 20ug / The inertial navigation sampling period is 10ms, and the satellite receiver speed accuracy is... Position accuracy is The satellite receiver sampling period is 1 second.

[0023] Setting the initial attitude of the precise airdrop inertial navigation device using Euler angles can be divided into two cases: small attitude angle and large attitude angle.

[0024] Small attitude angles are set as follows: pitch angle is 1°; roll angle is 2°; azimuth angle is 3°.

[0025] The large attitude angles are set as follows: pitch angle 30°; roll angle 60°; azimuth angle 120°.

[0026] The initial attitude was calculated using both the method of this invention and the existing method mentioned in the background (patent publication number CN112099071B), and the results are as follows. Figures 2-13 The figures show the estimation results of the initial attitude angles at small and large angles obtained by the two methods, respectively. As can be seen from the figures, regardless of the size of the initial attitude angle, the method of this invention can complete the correct estimation of the initial attitude within 10 seconds, achieving high-precision alignment quickly. In comparison, existing methods, due to the use of the TRIAD algorithm for initial attitude calculation, only utilize partial observation vector information, resulting in insufficient information utilization, susceptibility to measurement noise interference, and a longer time required for alignment results to stabilize. In contrast, the method of this invention employs a multi-vector recursive estimation algorithm based on Rodrigue parameters, which can fully utilize all effective measurement information, has stronger robustness to noise, significantly improves alignment accuracy, and can output alignment results in real time.

[0027] Example 2: This embodiment is based on an inertial navigation / satellite integrated navigation method for precise airdrop and rapid aerial alignment, and is implemented according to the following steps: Step 1: Power on the navigation device in the air. After the GNSS positioning is normal, start the alignment mode and record the initial latitude of the carrier at the start of alignment. ,longitude Initial velocity And establish the carrier's inertial coordinate system based on the start time. Navigation inertial coordinate system ; Step 2, in a periodic manner Angular rates measured by a triaxial gyroscope and a triaxial accelerometer were collected. Comparison data ,in , , and , , These are the triaxial angular velocity and specific force, respectively. Indicates the carrier coordinate system. These represent the three axes of the load system: right, front, and top. Step 3, in cycles Read and analyze satellite receiver information to obtain real-time data from the carrier. Time, location, and speed, where location includes geographic latitude. ,longitude and height The speed includes the eastward speed in the local geographic coordinate system. Northbound speed And the speed of the sky ,and for Integer multiples of, , It is a positive integer; Step 4: Calculate the attitude matrix of the carrier system. and Time comparison integral ; Step 5: Calculate the navigation system attitude matrix and acceleration integral ; Step 6: Integral calculated in Steps 4 and 5 and After normalization, we get and ; Step 7: Complete the linear optimal estimation recursive process for multi-vector attitude determination based on Rodrigue parameters; Step 8: Determine if If the condition is met, proceed to step 9; otherwise, return to step 2. Step 9: Based on the Rodrigues parameters in Step 7 The calculation results are used to calculate the attitude matrix. ; Step 10: Calculate the real-time attitude matrix ; Step 11: Determine if alignment is complete. If not, return to Step 2 to continue; if complete, proceed with the steps calculated in Step 10. This is the final alignment result, and the alignment is now complete.

[0028] Example 3: Based on Example 2, the carrier inertial coordinate system established in step 1 Navigation inertial coordinate system as follows: —The coordinate system of the precision airdrop inertial navigation device carrier is determined by the “right-front-up” direction of the inertial measurement unit; —The carrier's inertial coordinate system, at the initial moment of alignment, is artificially set to the carrier coordinate system. By "freezing" in inertial space, the carrier's inertial coordinate system is obtained. ; —Navigation coordinate system, the navigation coordinate system is selected as the "East-North-Sky" geographic coordinate system; —The navigation inertial coordinate system, at the initial moment of alignment, is manually adjusted. By "freezing" in inertial space, the navigation inertial coordinate system is obtained. .

[0029] Example 4: Based on Example 3, in step 4, the attitude matrix The attitude differential equation is:

[0030] in, Indicates the gyroscope output angular velocity The cross product of the antisymmetric matrix, Represents the coordinate system of the inertial navigation vehicle to the carrier inertial coordinate system The attitude transformation matrix, Represents a third-order identity matrix; Time comparison integral The calculation formula is as follows:

[0031] The calculation in the above formula is based on the single-sample algorithm for velocity calculation in strapdown inertial navigation systems, namely:

[0032] in, , .

[0033] Example 5: Based on Example 4, in step 5, the attitude matrix Position information output from satellite receiver is analyzed and calculated:

[0034] In the formula, , where represents the longitude value rotated relative to the inertial frame during the carrier alignment process. This represents the Earth's rotational angular rate; Comparative integral The calculation formula is as follows:

[0035] The above formula is equivalent to:

[0036] In the formula, For satellite receiver The speed output at any given moment; and Received by satellite The location information at a given time is calculated, where, , , The calculation is then performed using the Earth's gravity model: ; The discrete update method for the above formula is:

[0037] In the formula:

[0038]

[0039] .

[0040] Example 6: Based on Example 5, the specific recursive process of step 7 is as follows: (1) When At that time, perform recursive initialization: , , ; (2) When When recursively, proceed as follows:

[0041]

[0042]

[0043]

[0044]

[0045]

[0046] (3) ; (4) When At that time, obtained by recursive update and Solve for the Rodrigues parameters : .

Claims

1. A method for precise airdrop and rapid aerial alignment based on inertial navigation / satellite integrated navigation, characterized in that: The method is as follows: after the navigation device is powered on, the carrier inertial coordinate system and the navigation inertial coordinate system are established through inertial solidification. The angular rate and force data of the inertial measurement unit and the position and velocity data of the satellite receiver are periodically collected. The carrier system attitude tracking, force integration, navigation system attitude tracking and acceleration integration are calculated in sequence, and the integration is normalized. The Rodrigues parameters corresponding to the initial attitude of the inertial navigation system are recursively solved by a multi-vector attitude determination recursion algorithm, and then the real-time attitude matrix is ​​calculated. This process is repeated until alignment is completed.

2. The method for precise airdrop and rapid aerial alignment based on inertial navigation / satellite integrated navigation according to claim 1, characterized in that, The specific steps are as follows: Step 1: Power on the navigation device in the air. After the GNSS positioning is normal, start the alignment mode and record the initial latitude of the carrier at the start of alignment. ,longitude Initial velocity And establish the carrier's inertial coordinate system based on the start time. Navigation inertial coordinate system ; Step 2, in a periodic manner Angular rates measured by a triaxial gyroscope and a triaxial accelerometer were collected. Comparison data ,in , , and , , These are the triaxial angular velocity and specific force, respectively. Indicates the carrier coordinate system. These represent the three axes of the load system: right, front, and top. Step 3, in cycles Read and analyze satellite receiver information to obtain real-time data from the carrier. Time, location, and speed, where location includes geographic latitude. ,longitude and height The speed includes the eastward speed in the local geographic coordinate system. Northbound speed And the speed of the sky ,and for Integer multiples of, , It is a positive integer; Step 4: Calculate the attitude matrix of the carrier system. and Time comparison integral ; Step 5: Calculate the navigation system attitude matrix and acceleration integral ; Step 6: Integral calculated in Steps 4 and 5 and After normalization, we get and ; Step 7: Complete the linear optimal estimation recursive process for multi-vector attitude determination based on Rodrigue parameters; Step 8: Determine if If the condition is met, proceed to step 9; otherwise, return to step 2. Step 9: Based on the Rodrigues parameters in Step 7 The calculation results are used to calculate the attitude matrix. ; Step 10: Calculate the real-time attitude matrix ; Step 11: Determine if alignment is complete. If not, return to Step 2 to continue; if complete, proceed with the steps calculated in Step 10. This is the final alignment result, and the alignment is now complete.

3. The method for precise airdrop and rapid aerial alignment based on inertial navigation / satellite integrated navigation according to claim 2, characterized in that, The carrier inertial coordinate system established in step 1 Navigation inertial coordinate system as follows: —The coordinate system of the precision airdrop inertial navigation device carrier is determined by the "right-front-up" direction of the inertial measurement unit; —The carrier's inertial coordinate system, at the initial moment of alignment, is artificially set to the carrier coordinate system. By "freezing" in inertial space, the carrier's inertial coordinate system is obtained. ; —Navigation coordinate system, the navigation coordinate system is selected as the "East-North-Sky" geographic coordinate system; —The navigation inertial coordinate system, at the initial moment of alignment, is manually adjusted. By "freezing" in inertial space, the navigation inertial coordinate system is obtained. .

4. The method for precise airdrop and rapid aerial alignment based on inertial navigation / satellite integrated navigation according to claim 2, characterized in that, In step 4, the attitude matrix The attitude differential equation is: in, Indicates the gyroscope output angular velocity The cross product of the antisymmetric matrix, Represents the coordinate system of the inertial navigation vehicle to the carrier inertial coordinate system The attitude transformation matrix, Represents a third-order identity matrix; Time comparison integral The calculation formula is as follows: The calculation in the above formula is based on the single-sample algorithm for velocity calculation in strapdown inertial navigation systems, namely: in, , .

5. The method for precise airdrop and rapid aerial alignment based on inertial navigation / satellite integrated navigation according to claim 2, characterized in that, In step 5, the attitude matrix Position information output from satellite receiver is analyzed and calculated: In the formula, , where represents the longitude value rotated relative to the inertial frame during the carrier alignment process. This represents the Earth's rotational angular rate; Comparative integral The calculation formula is as follows: The above formula is equivalent to: In the formula, For satellite receiver The speed output at any given moment; and Received by satellite The location information at a given time is calculated, where, , , The calculation is then performed using the Earth's gravity model: ; The discrete update method for the above formula is: In the formula: 。 6. The method for precise airdrop and rapid aerial alignment based on inertial navigation / satellite integrated navigation according to claim 2, characterized in that, The specific recursive process of step 7 is as follows: (1) When At that time, perform recursive initialization: , , ; (2) When When recursively, proceed as follows: （3） ； (4) When At that time, obtained by recursive update and Solve for the Rodrigues parameters : 。 7. The method for precise airdrop and rapid aerial alignment based on inertial navigation / satellite integrated navigation according to claim 2, characterized in that, In step 9, the attitude matrix The calculation formula is: in, pose matrix The corresponding Rodrigue parameters.

8. The method for precise airdrop and rapid aerial alignment based on inertial navigation / satellite integrated navigation according to claim 2, characterized in that, In step 10, the attitude matrix of the carrier system obtained in step 4 is used. The navigation system attitude matrix obtained in step 5 and the attitude matrix obtained in step 9 Calculate the real-time attitude matrix : 。

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