Underwater platform inertial navigation calibration method and device

Abstract

The invention belongs to the technical field of navigation positioning, and provides an underwater platform inertial navigation calibration method and device in order to solve the problem that an inertial navigation system of an existing underwater carrying platform is large in calibration error, and the method comprises the steps that a plurality of buoys are released, and after the buoys are exposed out of the water surface, satellite positioning signals are received for positioning; the underwater platform continuously sends inquiry signals through the bow underwater acoustic transducer and the stern underwater acoustic transducer; after receiving the inquiry signal, the buoy sends satellite positioning information and a response signal back to the underwater platform; according to the satellite positioning information and the underwater acoustic positioning information, coordinates of a bow underwater acoustic transducer and a stern underwater acoustic transducer are obtained through calculation; and according to the coordinates of the bow underwater acoustic transducer and the stern underwater acoustic transducer, obtaining real-time coordinates and course of the inertial navigation system so as to calibrate the inertial navigation system. On one hand, the underwater carrying platform is high in concealment and free in operation range, and the limitation of an operation area is broken through; on the other hand, the problem that the underwater GNSS technology is large in error is solved, and the precision of inertial navigation calibration is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of navigation and positioning, and more specifically, relates to an inertial navigation calibration method and device for an underwater platform. Background Art

[0002] GPS (Global Positioning System) positioning technology is widely used for high-precision navigation and positioning of various moving carriers at sea, on land, and in the air. Since electromagnetic wave signals cannot propagate in water, submarines, underwater robots, and other underwater vehicles mainly use inertial navigation systems for underwater navigation and positioning. Generally, inertial navigation systems used by large underwater vehicles have relatively high autonomous navigation accuracy, but the position error of the inertial navigation accumulates over time. When the error accumulates to a certain extent, the underwater vehicle must surface regularly to obtain position information for readjusting and calibrating the inertial navigation system. Extending the recalibration period and underwater endurance time of the underwater vehicle's inertial navigation system is the key to improving its stealth.

[0003] The technology of obtaining the relative position between an underwater target and a GPS antenna on the water surface by means of underwater acoustic positioning and other technologies, thereby extending GPS positioning on the water surface to underwater, is called underwater GPS technology. Among them, the ultra-short baseline positioning (USBL) in underwater acoustic positioning technology has an acoustic array composed of only a compact transducer, with a simple system, convenient installation, easy operation, high ranging accuracy, and the transducer can be designed into an integrated structure with the inertial navigation system, enabling the device to be plug-and-play without fixed installation, and the positioning accuracy at a long distance can be improved by using a multi-element array.

[0004] Traditional underwater GPS technology generally uses a single buoy and a single set of USBL for calibration, with limited positioning accuracy; or conducts underwater positioning in waters where transponders have been pre-laid on the seabed, and the operation range is limited. Summary of the Invention

[0005] The embodiments of the present application provide an inertial navigation calibration method and device for an underwater platform, which can, on the one hand, solve the problems that a long-endurance underwater vehicle needs to surface, has poor stealth, and needs to operate in a pre-laid environment, etc.; on the other hand, solve the problem of large errors in underwater GNSS technology and improve the accuracy of inertial navigation calibration.

[0006] In a first aspect, the embodiments of the present application provide an inertial navigation calibration method for an underwater platform, including: Releasing a plurality of buoys, and after the buoys emerge from the water surface, receiving satellite positioning signals for positioning; The underwater platform continuously sends interrogation signals through a bow underwater acoustic transducer and a stern underwater acoustic transducer; after receiving the interrogation signals, the buoys send the satellite positioning information and response signals back to the underwater platform; Based on the satellite positioning information and the underwater acoustic positioning information, the coordinates of the bow underwater acoustic transducer and the stern underwater acoustic transducer are calculated; Based on the coordinates of the bow underwater acoustic transducer and the stern underwater acoustic transducer, the real-time coordinates and heading of the inertial navigation system are obtained, and the inertial navigation system is calibrated according to the obtained real-time coordinates and heading; the relative position relationship between the bow underwater acoustic transducer and the stern underwater acoustic transducer and the inertial navigation system is fixed and known. The calculation module of the underwater platform converts the geometric coordinates of the bow and stern underwater acoustic transducers to obtain the real-time coordinates and heading of the inertial navigation system, and sends the obtained real-time coordinates and heading to the inertial navigation system, and the inertial navigation system is calibrated according to the received real-time coordinates and heading.

[0007] In some embodiments, a plurality of buoys are released. After the buoys emerge from the water surface, they receive satellite positioning signals for positioning, including: the underwater platform travels along a preset route and sequentially releases a plurality of buoys. After the buoys emerge from the water surface, they receive satellite positioning signals for positioning.

[0008] In some embodiments, the buoy includes a satellite signal positioning module, an antenna, an underwater acoustic communication module, and an underwater acoustic transponder. The buoy is positioned through the satellite signal positioning module and the antenna. The underwater acoustic transponder is used to receive the interrogation signal sent by the underwater acoustic transducer. The buoy transmits the positioning information and the response signal to the underwater platform through the underwater acoustic communication module and the underwater acoustic transponder.

[0009] In some embodiments, based on the satellite positioning information and the underwater acoustic positioning information, calculating the coordinates of the bow underwater acoustic transducer and the stern underwater acoustic transducer includes: Step 1, assume that at any k moment, the coordinates of the underwater acoustic transducer are , the position of the underwater acoustic transponder of the buoy is , the round-trip time of the acoustic ranging signal is , and the sound speed is C. Then the basic observation equation from i to j is:

[0010] Among them, is the geometric distance from i to j, is the distance observation value, is the sound speed measurement error, is the time delay error of the underwater acoustic transducer, is the time delay error of the underwater acoustic transponder, is the random error of acoustic ranging. i represents the underwater acoustic transducer, and j represents the buoy; Taking the position of the inertial navigation system on the underwater platform reduced to the position of the underwater acoustic transducer as , then Linearizing the observation equation to obtain the error equation as:

[0011] Among them, , , is the coordinate correction; if the variance of the epoch observer is , and the variance of unit weight is , a stochastic model can be constructed:

[0012] Among them is the incident angle between the buoy j and the transducer i. At this time, the variance-covariance matrix is:

[0013] Select the first buoy that meets the preset conditions as the reference buoy; Step 2, when the underwater acoustic transducer synchronously observes the reference buoy and the buoy j, taking the difference between the observation equations of the buoy j and the reference buoy can eliminate the transducer time-delay error and greatly weaken the sound speed measurement systematic error , that is

[0014] The single-difference observation equation between buoys can be obtained as:

[0015] Among them, represents the single-difference symbol of the transponder difference between buoys, is the sound speed measurement error of the buoy j, is the sound speed measurement error of the reference buoy, is the difference in observed values between the buoy j and the reference buoy, is the observation matrix composed of direction cosines, dX is the coordinate correction, is the time-delay error between the buoy j and the reference buoy, is the random error of acoustic ranging; Let the single-difference conversion factor between buoys:

[0016] According to the error propagation law, the variance-covariance matrix of the single-difference between buoys is:

[0017] Step 3, when the bow underwater acoustic transducer and the stern underwater acoustic transducer synchronously observe the buoy j, the transducer and transponder time-delay errors can be eliminated simultaneously, and the sound speed measurement error can be greatly weakened. Thus, the double-difference observation equation is obtained:

[0018] Among them, is a double-difference symbol; Variance-covariance matrix of single differences between buoys is:

[0019] Step 4, the weighted least squares model is:

[0020] where L is the observed value, A is the coefficient matrix, X is the state vector, v is the residual of the observed value, E(v)=0 is the least squares assumption, is the mean square error of unit weight, and P is the weight matrix of each observation equation; Solve under the least squares criterion, substitute the double-difference observation equation and the stochastic model, and calculate the geometric coordinates of the bow underwater transducer and the stern underwater transducer.

[0021] In some embodiments, select the buoy with the largest elevation angle or the strongest acoustic signal quality as the reference buoy; or determine the reference buoy according to the elevation angle and the acoustic signal quality.

[0022] In some embodiments, it further includes recovering the buoy after the inertial navigation system is calibrated.

[0023] In a second aspect, the present application provides an underwater platform inertial navigation calibration device, including: Multiple buoys floating on the water surface for receiving satellite positioning signals for positioning; An underwater platform for continuously sending interrogation signals through a bow underwater transducer and a stern underwater transducer; The buoy is used for sending the satellite positioning information and the response signal back to the underwater platform after receiving the interrogation signal; The underwater platform is used for: calculating the coordinates of the bow underwater transducer and the stern underwater transducer according to the satellite positioning information and the underwater acoustic positioning information; obtaining the real-time coordinates and heading of the inertial navigation system according to the coordinates of the bow underwater transducer and the stern underwater transducer, and the inertial navigation system is calibrated according to the obtained real-time coordinates and heading; the relative position relationship between the bow underwater transducer and the stern underwater transducer and the inertial navigation system is fixed and known, and the calculation module of the underwater platform converts the geometric coordinates of the bow and stern underwater transducers to obtain the real-time coordinates and heading of the inertial navigation system, and sends the obtained real-time coordinates and heading to the inertial navigation system, and the inertial navigation system is calibrated according to the received real-time coordinates and heading.

[0024] In a third aspect, an embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, it implements the steps of the method described in any one of the above.

[0025] Fourthly, the present application provides an underwater vehicle platform, and the underwater vehicle platform calibrates an inertial navigation system by using any one of the above underwater platform inertial navigation calibration methods.

[0026] The underwater platform inertial navigation calibration method and device in the embodiments of the present application have the following beneficial effects: On the one hand, the present application solves the problems that a long-endurance underwater vehicle platform needs to surface, has poor concealment, and needs to operate in a pre-laid environment, etc., has high concealment, a free operation range, and breaks through the limitation of the operation area; on the other hand, it solves the problem of large errors in underwater GNSS technology and improves the accuracy of inertial navigation calibration. Description of the Drawings

[0027] Figure 1 is a schematic flow chart of the underwater platform inertial navigation calibration method in the embodiments of the present application; Figure 2 is a schematic diagram of the principle of dual-difference underwater positioning and inertial navigation calibration of a vehicle based on a buoy array in the present application; Figure 3 is a schematic diagram of the principle of the buoy structure in the present application; Figure 4 is a flow chart of the high-precision underwater platform inertial navigation calibration method based on GNSS / hydroacoustic buoy array in the present application; Figure 5 is a schematic diagram of the route adopted for releasing buoys in the present application; Figure 6 is a flow chart of the dual-difference underwater positioning and inertial navigation calibration program of the underwater vehicle platform navigation system. Detailed Embodiments

[0028] The present application will be further introduced below with reference to the drawings and embodiments.

[0029] In the following description, the terms "first" and "second" are only for the purpose of description and cannot be construed as indicating or implying relative importance. The following description provides multiple embodiments of the present invention, and different embodiments can be replaced or combined, so the present application can also be considered to include all possible combinations of the same and / or different embodiments described. Thus, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then the present application should also be considered to include embodiments containing one or more all other possible combinations of features A, B, C, and D, although such embodiments may not be explicitly described in the following content.

[0030] As Figure 1As shown in the figure, the inertial navigation calibration method for the underwater platform of the present application includes: S101, releasing a plurality of buoys. After the buoys emerge above the water surface, satellite positioning signals are received for positioning; S103, the underwater platform continuously sends interrogation signals through the bow underwater acoustic transducer and the stern underwater acoustic transducer; after the buoys receive the interrogation signals, the satellite positioning information and the response signals are sent back to the underwater platform; S105, according to the satellite positioning information and the underwater acoustic positioning information, the coordinates of the bow underwater acoustic transducer and the stern underwater acoustic transducer are calculated; S107, according to the coordinates of the bow underwater acoustic transducer and the stern underwater acoustic transducer, the real-time coordinates and heading of the inertial navigation system are obtained, and the inertial navigation system is calibrated according to the obtained real-time coordinates and heading.

[0031] On the one hand, the present application can solve the problems that the long-endurance underwater vehicle platform needs to surface, has poor concealment, and needs to operate in a pre-laid environment, etc.; on the other hand, it solves the problem of large errors in underwater GNSS (Global Navigation Satellite System) technology, and improves the accuracy of inertial navigation calibration.

[0032] Figure 2 It is a schematic diagram of dual-difference underwater positioning and inertial navigation calibration of the vehicle based on the buoy array in the present application. As Figure 2 shown, the long-endurance positioning of the underwater vehicle platform 12 mainly relies on the inertial navigation system 15. A bow underwater acoustic transducer 13 is installed at the bow of the underwater vehicle platform 12, and a stern underwater acoustic transducer 14 is installed at the stern. The bow underwater acoustic transducer 13 and the stern underwater acoustic transducer 14 are used for underwater acoustic communication and inertial navigation calibration. The buoy 11 is positioned through the GNSS satellite 10.

[0033] Figure 3 It is a schematic diagram of the structure of the buoy. As Figure 3 shown, the buoy 11 integrates GNSS and USBL technologies. The accurate position of the buoy 11 is obtained through GNSS, and then the position of the buoy and the position of the buoy relative to the vehicle are transmitted back to the underwater vehicle platform 12 through the acoustic transponder part and the acoustic communication module of USBL, which can extend the function of GNSS underwater. The buoy 11 includes a GNSS positioning module 112, a GNSS antenna 111, an underwater acoustic communication module 113, and an underwater acoustic transponder 114. The buoy 11 is positioned through the GNSS positioning module 112 and the GNSS antenna 111. The underwater acoustic transponder 114 is used to receive the interrogation signals sent by the underwater acoustic transducer. The buoy 11 transmits the positioning information and the response signals to the underwater platform through the underwater acoustic communication module 113 and the underwater acoustic transponder 114.

[0034] The inertial navigation calibration method for the underwater platform of the present application includes the following steps: (1) As Figure 4 and Figure 5As shown, after entering the inertial navigation calibration process, four buoys are successively released along a specific route. Here, the route is the route of the underwater vehicle platform. Since, compared with hovering, the underwater vehicle platform always moves forward at an economic speed, which consumes less energy and is easier to control. Some underwater vehicle platforms cannot even hover because they do not have the ability to adjust buoyancy. Therefore, this application designs a route that can make the underwater vehicle platform operate as much as possible within the geometric configuration of several buoy arrays. Compared with routes such as straight lines or round trips, the HDOP (horizontal dilution of precision) will be smaller and the positioning accuracy will be higher.

[0035] (2) After the buoy emerges from the water surface, it receives GNSS signals for positioning.

[0036] (3) As Figure 5 shown, the transducers at the bow and stern of the underwater vehicle platform continuously send interrogation signals.

[0037] (4) After the underwater acoustic transponder in the buoy receives the interrogation signal, it immediately feeds back the response signal and converts the GNSS positioning information corresponding to the interrogation signal received at time t into an acoustic signal and transmits it back to the underwater vehicle platform.

[0038] (5) After receiving the signal, execute the double-difference solution program to calculate the heading and position of the underwater vehicle platform. The program flow is as Figure 6 shown, and the detailed steps are as follows: Step ①, assume that at any k moment, the coordinates of the underwater acoustic transducer are , the position of the underwater acoustic transponder of the buoy is , the round-trip time of the acoustic ranging signal is , and the speed of sound is C. Then the basic observation equation from i to j is:

[0039] Among them, is the geometric distance from i to j, i represents the transducer, j represents the buoy, is the distance observation value, is the speed-of-sound measurement error, is the time-delay error of the underwater acoustic transducer, is the time-delay error of the underwater acoustic transponder, is the random error of acoustic ranging, i represents the underwater acoustic transducer, j represents the buoy; Taking the position of the inertial navigation system on the underwater platform reduced to the position of the underwater acoustic transducer as , then Linearize the observation equation to obtain the error equation as:

[0040] Among them, , , is the coordinate correction; if the variance of the epoch observer is , an observation period t is an epoch, and the variance of unit weight is , a stochastic model can be constructed:

[0041] where is the incident angle between buoy j and transducer i. At this time, the variance-covariance matrix is:

[0042] Select the first buoy that meets the preset conditions as the reference buoy; for example, as the reference buoy, a buoy with the largest elevation angle or the strongest acoustic signal quality can be selected, or a result value can be calculated by weighting the two criteria (elevation angle and acoustic signal quality), and the buoy with the largest result value is used as the reference buoy, denoted as reference buoy 1.

[0043] Step ②, when the underwater acoustic transducer synchronously observes buoy j and the reference buoy, taking the difference between the observation equations of buoy j and the reference buoy can eliminate the transducer time-delay error and greatly weaken the sound velocity measurement systematic error , that is

[0044] The observation equation of the single difference between buoys can be obtained as:

[0045] where represents the single difference symbol of the transponder difference between buoys, is the sound velocity measurement error of buoy j, is the sound velocity measurement error of the reference buoy, is the difference between the observation values of buoy j and the reference buoy, is the observation matrix composed of direction cosines, dX is the coordinate correction, is the time-delay error between buoy j and the reference buoy, is the random error of acoustic ranging; Let the single difference conversion factor between buoys:

[0046] According to the error propagation law, the variance-covariance matrix of the single difference between buoys is:

[0047] Step ③, when the bow underwater transducer and the stern underwater transducer perform synchronous observations on buoy j, the time-delay errors of the transducers and the transponder can be eliminated simultaneously, and the sound speed measurement error can be greatly reduced. Thus, the double-difference observation equation is obtained:

[0048] where is the double-difference symbol; The variance-covariance matrix of the single difference between buoys is:

[0049] Step ④, the weighted least squares model is:

[0050] where it is assumed that the observation model is linear, that is, there is such a least squares model between the observation value L and the state X. L is the observation value, A is the coefficient matrix, X is the state vector, v is the observation value residual, and E(v)=0 is the least squares assumption. is the mean square error of unit weight, and P is the weight matrix of each observation equation; Solve under the least squares criterion, substitute the double-difference observation equation and the stochastic model, and calculate the geometric coordinates of the bow underwater transducer and the stern underwater transducer.

[0051] Step ⑤, it can be considered that there is a rigid connection between the transducer and the inertial navigation, that is, the relative position relationship between the bow underwater transducer and the stern underwater transducer and the inertial navigation system is fixed and known. The calculation module of the underwater vehicle platform converts the geometric coordinates of the bow and stern underwater transducers to obtain the real-time high-precision coordinates and heading of the inertial navigation system.

[0052] Step ⑥, send the obtained real-time coordinates and heading to the inertial navigation system, and the inertial navigation system calibrates according to the received real-time coordinates and heading.

[0053] (6) After completing the inertial navigation calibration, recover the buoy.

[0054] The high-precision underwater platform inertial navigation calibration method for the GNSS / hydroacoustic buoy array provided by this application includes: after the carrier reaches the deep-sea operation area, it moves along a specific route, releases the buoys, and waits for the buoys to float to the water surface to receive and record continuously valid GNSS information; after all the buoys are released, the underwater vehicle platform continuously sends interrogation signals through the USBL transducers at the bow and stern; after the buoys receive the interrogation signals, they send the corresponding GNSS information and response signals back to the underwater vehicle platform. By integrating the GNSS information and the USBL hydroacoustic positioning information, the internal navigation computer of the navigation system of the underwater vehicle platform completes the process of double-difference underwater positioning, obtains the positions of the bow and stern USBL transducers and the heading information of the underwater vehicle platform. It can be considered that the transducers and the inertial navigation are rigidly connected (that is, the relative position relationship between the two is fixed and known). Therefore, through the geometric coordinates of the bow and stern transducers, the real-time high-precision coordinates and heading of the inertial navigation can be obtained through coordinate transformation.

[0055] In this application, the buoy is equipped with a built-in GNSS, which is convenient for obtaining initial positioning information and has high accuracy; as a supporting device for the underwater vehicle platform, the buoy does not need to be deployed in advance, has high concealment, a free operation range, and breaks through the limitations of the operation area; based on the double-difference hydroacoustic positioning technology, it solves the problems of large underwater positioning errors and limited accuracy, and improves the accuracy of inertial navigation calibration.

[0056] This application also provides an underwater platform inertial navigation calibration device, including: a plurality of buoys floating on the water surface for receiving satellite positioning signals for positioning; an underwater platform for continuously sending interrogation signals through the bow hydroacoustic transducer and the stern hydroacoustic transducer; the buoy is used to send the satellite positioning information and the response signal back to the underwater platform after receiving the interrogation signal; the underwater platform is used to: calculate the coordinates of the bow hydroacoustic transducer and the stern hydroacoustic transducer according to the satellite positioning information and the hydroacoustic positioning information; obtain the real-time coordinates and heading of the inertial navigation system according to the coordinates of the bow hydroacoustic transducer and the stern hydroacoustic transducer, and the inertial navigation system is calibrated according to the obtained real-time coordinates and heading; the relative position relationship between the bow hydroacoustic transducer and the stern hydroacoustic transducer and the inertial navigation system is fixed and known, and the calculation module of the underwater platform converts the geometric coordinates of the bow and stern hydroacoustic transducers to obtain the real-time coordinates and heading of the inertial navigation system, and sends the obtained real-time coordinates and heading to the inertial navigation system; the inertial navigation system is calibrated according to the received real-time coordinates and heading.

[0057] In this application, the embodiment of the underwater platform inertial navigation calibration device is basically similar to the embodiment of the underwater platform inertial navigation calibration method. For the related parts, please refer to the introduction of the embodiment of the underwater platform inertial navigation calibration method.

[0058] This application also provides an underwater vehicle platform, and the underwater vehicle platform uses any one of the above-mentioned underwater platform inertial navigation calibration methods to calibrate the inertial navigation system.

[0059] An embodiment of the present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps of the above-mentioned underwater platform inertial navigation calibration method are implemented. Among them, the computer-readable storage medium may include, but is not limited to, any type of disk, including floppy disks, optical disks, DVDs, CD-ROMs, microdrives, and magneto-optical disks, ROMs, RAMs, EPROMs, EEPROMs, DRAMs, VRAMs, flash memory devices, magnetic cards or optical cards, nanosystems (including molecular memory ICs), or any type of medium or device suitable for storing instructions and / or data.

[0060] The above introduction is only the preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for calibrating an underwater platform inertial navigation system, characterized in that: include: Release multiple buoys, and after the buoys emerge from the water, they receive satellite positioning signals for positioning; The underwater platform continuously sends interrogation signals through the bow hydroacoustic transducer and the stern hydroacoustic transducer; after receiving the interrogation signal, the buoy sends the satellite positioning information and the response signal back to the underwater platform; The coordinates of the bow hydroacoustic transducer and the stern hydroacoustic transducer are calculated based on the satellite positioning information and the hydroacoustic positioning information; According to the coordinates of the bow hydroacoustic transducer and the stern hydroacoustic transducer, the real-time coordinates and heading of the inertial navigation system are obtained, and the inertial navigation system is calibrated according to the obtained real-time coordinates and heading; the relative position relationship between the bow hydroacoustic transducer and the stern hydroacoustic transducer and the inertial navigation system is fixed and known, and the computing module of the underwater platform converts the geometric coordinates of the bow and stern hydroacoustic transducers to obtain the real-time coordinates and heading of the inertial navigation system, and sends the obtained real-time coordinates and heading to the inertial navigation system, and the inertial navigation system is calibrated according to the received real-time coordinates and heading.

2. The underwater platform inertial navigation calibration method according to claim 1, characterized in that: A plurality of buoys are released, and after the buoys are exposed to the water surface, satellite positioning signals are received for positioning, including: an underwater platform travels according to a preset route, and a plurality of buoys are released in sequence, and after the buoys are exposed to the water surface, satellite positioning signals are received for positioning.

3. The underwater platform inertial navigation calibration method according to claim 2, characterized in that: The buoy includes a satellite signal positioning module, an antenna, a hydroacoustic communication module and a hydroacoustic transponder. The buoy is positioned by the satellite signal positioning module and the antenna. The hydroacoustic transponder is used to receive the inquiry signal sent by the hydroacoustic transducer. The buoy transmits the positioning information and the response signal to the underwater platform through the hydroacoustic communication module and the hydroacoustic transponder.

4. The underwater platform inertial navigation calibration method according to any one of claims 1 to 3, characterized in that: According to the satellite positioning information and the hydroacoustic positioning information, the coordinates of the bow hydroacoustic transducer and the stern hydroacoustic transducer are calculated, including: Step 1: Assume that the coordinates of the underwater acoustic transducer at any time k are , the hydroacoustic transponder position of the buoy is , the round trip time of the acoustic ranging signal is , the speed of sound is C, then the basic observation equation from i to j is: in, is the geometric distance from i to j, is the observed distance, is the sound velocity measurement error, is the delay error of the underwater acoustic transducer, is the delay error of the underwater acoustic transponder, is the random error of acoustic ranging, i represents the hydroacoustic transducer, and j represents the buoy; The position of the inertial navigation system on the underwater platform is converted to the position on the hydroacoustic transducer: ,but The error equation obtained by linearizing the observation equation is: in, , , is the coordinate correction number; if the variance of the epoch observer is , the unit weight variance is , a random model can be constructed: in is the incident angle from buoy j to transducer i, then the variance-covariance matrix for: Selecting a first buoy that meets preset conditions as a reference buoy; Step 2: When the hydroacoustic transducer performs synchronous observations on the reference buoy and buoy j, the difference between the observation equations of buoy j and the reference buoy can eliminate the transducer delay error and greatly reduce the sound velocity measurement system error. ,Right now The single difference observation equation between buoys is obtained as follows: in, Represents the single difference symbol of the transponders between buoys, is the sound velocity measurement error of buoy j, is the sound velocity measurement error of the reference buoy, is the difference in observations between buoy j and the reference buoy, is the observation matrix composed of direction cosines, dX is the coordinate correction number, is the time delay error between buoy j and the reference buoy, is the random error of acoustic ranging; Assume the single difference conversion factor between buoys: According to the error propagation law, the variance-covariance matrix of the single difference between buoys is for: Step 3: When the bow hydroacoustic transducer and the stern hydroacoustic transducer synchronously observe the buoy j, the time delay errors of the transducer and the transponder can be eliminated at the same time, and the sound velocity measurement error can be greatly weakened, thereby obtaining the double difference observation equation: in, is the double difference symbol; Variance-covariance matrix of single differences between buoys for: Step 4, the weighted least squares model is: Among them, L is the observation value, A is the coefficient matrix, X is the state vector, v is the observation value residual, and E(v)=0 is the least squares assumption. is the unit weighted error, P is the weight matrix of each observation equation; The solution is obtained under the least squares criterion, and the double-difference observation equation and the random model are introduced to calculate the geometric coordinates of the bow and stern hydroacoustic transducers.

5. The underwater platform inertial navigation calibration method according to claim 4, characterized in that: Select the buoy with the largest elevation angle or the strongest acoustic signal quality as the reference buoy; or determine the reference buoy based on the elevation angle and the acoustic signal quality.

6. The underwater platform inertial navigation calibration method according to any one of claims 1 to 3, characterized in that: It also includes recovering the buoy after the inertial navigation system is calibrated.

7. An underwater platform inertial navigation calibration device, characterized in that: include: A plurality of buoys, each buoy floating on the water surface and used to receive satellite positioning signals for positioning; An underwater platform for continuously sending interrogation signals via a bow hydroacoustic transducer and a stern hydroacoustic transducer; The buoy is used to send satellite positioning information and a response signal back to the underwater platform after receiving the inquiry signal; The underwater platform is used to: calculate the coordinates of the bow hydroacoustic transducer and the stern hydroacoustic transducer according to the satellite positioning information and the hydroacoustic positioning information; obtain the real-time coordinates and heading of the inertial navigation system according to the coordinates of the bow hydroacoustic transducer and the stern hydroacoustic transducer, and calibrate the inertial navigation system according to the obtained real-time coordinates and heading; the relative position relationship between the bow hydroacoustic transducer and the stern hydroacoustic transducer and the inertial navigation system is fixed and known, and the calculation module of the underwater platform converts the geometric coordinates of the bow and stern hydroacoustic transducers to obtain the real-time coordinates and heading of the inertial navigation system, and sends the obtained real-time coordinates and heading to the inertial navigation system, and the inertial navigation system is calibrated according to the received real-time coordinates and heading.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method described in any one of claims 1 to 6 are implemented.

9. An underwater carrier platform, characterized in that: The underwater carrier platform uses the underwater platform inertial navigation calibration method described in any one of claims 1-6 to calibrate the inertial navigation system.

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