A method and system for underwater glider dead reckoning

Abstract

This invention discloses a method and system for dead reckoning of underwater gliders, belonging to the field of underwater glider navigation technology. The method includes the following steps: S1, acquiring basic data; S2, calculating position using gliding slope; S201, calculating the vertical velocity of the underwater glider based on the rate of change of depth data; S202, establishing a mathematical relationship between vertical velocity and marine environmental parameters; S203, calculating the gliding slope using the mathematical relationship and the glider's dynamic equations; S204, calculating the eastward and northward horizontal velocity components using the gliding slope and vertical velocity, combined with the heading angle; S205, calculating the position increment based on the eastward and northward horizontal velocity components using an integral algorithm, and updating the position based on the position increment; S3, ocean current compensation; and updating the position using ocean current velocity correction. This invention utilizes multiple types of data for underwater dead reckoning and leverages an ocean current compensation mechanism to improve the navigation performance of underwater gliders, thereby meeting the requirements for high-precision positioning.

Description

Technical Field

[0001] This invention belongs to the field of underwater glider navigation technology, and in particular relates to an underwater glider dead reckoning method and system. Background Technology

[0002] Underwater gliders, as advanced underwater exploration devices, play an increasingly important role in various fields such as marine scientific research, marine resource exploration, and marine environmental monitoring. They can operate autonomously for extended periods in the vast ocean, collecting a wealth of valuable data. However, accurate underwater navigation and positioning has always been a major challenge in this field. Traditional positioning methods, such as those based on a single hydrodynamic model or simple dead reckoning, often have significant errors and cannot meet the requirements for high-precision positioning.

[0003] While the Global Positioning System (GPS) provides relatively accurate location information on the surface of water, its signals cannot propagate effectively underwater, making it difficult for underwater gliders to directly acquire high-precision positioning data during underwater operations. To address this issue, researchers have been exploring and developing various alternative positioning technologies, such as acoustic positioning systems, inertial navigation systems, and underwater acoustic communication technologies. These technologies have compensated for some of GPS's shortcomings, but still have certain limitations.

[0004] For example, existing gliding slope models have certain limitations in practical applications. These models typically assume that ocean currents have a uniform and consistent influence on gliders, but in reality, the complexity and variability of ocean currents often render this assumption invalid. Furthermore, existing error correction mechanisms are not perfect and cannot fully account for the impact of various environmental factors on positioning accuracy. These factors all restrict further improvements in the positioning accuracy of underwater gliders and affect their performance in practical applications.

[0005] Therefore, to improve the positioning accuracy of underwater gliders, researchers need to further optimize and improve existing positioning models and algorithms, fully consider the influence of various environmental factors such as ocean currents, water temperature, and salinity, and combine them with advanced sensor technology to achieve more precise underwater positioning. Only in this way can underwater gliders play a greater role in marine scientific research and resource exploration, providing humanity with more accurate and abundant marine data. Summary of the Invention

[0006] To address the technical problems mentioned above, a method and system for underwater glider dead reckoning is proposed. This method utilizes data from multiple sensors for underwater dead reckoning and employs an innovative ocean current compensation mechanism to reduce the impact of various error factors on positioning accuracy, thereby improving the navigation performance of underwater gliders and meeting the high-precision positioning requirements of underwater gliders in the marine field.

[0007] The first objective of this invention is to provide a method for dead reckoning of underwater gliders, comprising:

[0008] S1. Acquire basic data, which includes the attitude angle, heading angle, depth data, marine environmental parameters, ocean current speed, dynamic pressure, and position information of the glider when it is on the water surface at different times.

[0009] S2. Position estimation using gliding inclination; specifically including:

[0010] S201. Calculate the vertical velocity of the underwater glider based on the rate of change of depth data;

[0011] S202. Construct the mathematical relationship between vertical velocity and marine environmental parameters;

[0012] S203. Calculate the gliding slope using the mathematical relationship and the glider dynamics equation;

[0013] S204. Calculate the eastward and northward horizontal velocity components by using the gliding slope and vertical velocity, combined with the heading angle.

[0014] S205. Based on the eastward and northward horizontal velocity components, calculate the position increment using an integration algorithm, and update the position based on the position increment;

[0015] S3, Ocean Current Compensation; Uses ocean current velocity to correct and update position.

[0016] Preferably, the attitude angles include pitch angle and roll angle.

[0017] Preferably, the marine environmental parameters include seawater density and seawater temperature.

[0018] Preferably, in S1, pressure data of the underwater glider is acquired using a pressure sensor, and depth data is calculated based on the pressure data;

[0019] In S202, the mathematical relation is expressed as follows: Where: q is dynamic pressure, v z ρ is the vertical velocity, ρ is the seawater density, and γ is the gliding angle.

[0020] Preferably, the glider's dynamic equations are:

[0021] (ql2 ) 2 bq -(1 / 4) -Bql 2 sin(γ)+B 2 cα -2 cos 2 (γ)=0

[0022] cα 2 +aαtan(γ)+bq -(1 / 4) =0

[0023] Where a, b, c are hydrodynamic coefficients, l is the glider length, B is buoyancy, and α is the angle of attack;

[0024] The relationship between pitch angle θ, glide angle γ, and angle of attack α is: γ = θ - α;

[0025] The gliding angle γ can be solved iteratively; the gliding slope is tanγ.

[0026] Preferably, the eastward horizontal velocity component v x The expression is:

[0027] Northward horizontal velocity component v y The expression is:

[0028] in, This refers to the heading angle;

[0029] The expression for the position increment is: Δx = v x Δt; Δy = v y Δt;

[0030] The expression for updating the position is: x n+1 =x n +Δx;y n+1 =y n +Δy.

[0031] Preferably, in S3, ocean current compensation is performed using a VMD-LSTM neural network;

[0032] Measuring the ocean current speed v around the glider current Decomposed into levels (v) current,x ,v current,y ) and vertical component v current,z ;

[0033] A VMD-LSTM neural network-based model for predicting ocean current impacts:

[0034] Δx current =f(v current,x ,…);

[0035] Δy current =g(v current,y ,…);

[0036] f and g are prediction functions; in dead reckoning, the influence of ocean currents is compensated for in real time.

[0037] x compensated =x calc +Δx current ;

[0038] y compensated =y calc +Δy current .

[0039] A second objective of this invention is to provide an underwater glider dead reckoning system, comprising:

[0040] The basic data acquisition module includes the attitude angle, heading angle, depth data, marine environmental parameters, ocean current speed, dynamic pressure, and position information of the underwater glider at different times.

[0041] The position estimation module uses gliding inclination to estimate position; specifically, it includes:

[0042] Calculate the vertical velocity of the underwater glider based on the rate of change of depth data;

[0043] Establish the mathematical relationship between vertical velocity and marine environmental parameters;

[0044] The gliding slope is calculated using the aforementioned mathematical relationships and the glider dynamics equations.

[0045] The eastward and northward horizontal velocity components are calculated using the gliding slope and vertical velocity, combined with the heading angle.

[0046] The position increment is calculated using an integral algorithm based on the eastward and northward horizontal velocity components, and the position is updated based on the position increment.

[0047] The ocean current compensation module uses ocean current velocity to correct and update the position.

[0048] The third objective of this patent is to provide a computer program product, including a computer program that, when executed by a processor, implements the aforementioned underwater glider dead reckoning method.

[0049] The fourth objective of this patent is to provide a computer-readable storage medium, including instructions that, when executed on a computer, cause the computer to perform the aforementioned underwater glider dead reckoning method.

[0050] The advantages and positive effects of this invention are as follows:

[0051] The core of this invention lies in the integration of multiple cutting-edge technologies, including but not limited to multi-source satellite positioning systems (such as GPS and BeiDou), high-precision sensor data processing techniques, and innovative ocean current compensation algorithms. Through the comprehensive application of these technologies, this invention can significantly improve the positioning accuracy of underwater gliders in complex and ever-changing marine environments. This improved positioning accuracy is crucial for the precise navigation of underwater gliders and also provides more reliable technical support for marine data collection and monitoring. As a result, underwater gliders can more accurately locate their own position during missions, effectively collect marine environmental data, and provide a solid technical foundation for marine scientific research and related applications. Attached Figure Description

[0052] Figure 1 A flowchart of a preferred embodiment of the present invention;

[0053] Figure 2 This is a flowchart illustrating position calculation using gliding inclination in a preferred embodiment of the present invention;

[0054] Figure 3 This is a schematic diagram of the calculation method during system operation in a preferred embodiment of the present invention;

[0055] Figure 4 This is a schematic diagram of the main angles of the underwater glider motion model in a preferred embodiment of the present invention;

[0056] Figure 5 This is a flowchart of the VMD-LSTM neural network prediction method in a preferred embodiment of the present invention;

[0057] Figure 6 This is an example diagram of dead reckoning results in a preferred embodiment of the present invention. Detailed Implementation

[0058] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed descriptions are given in conjunction with the accompanying drawings.

[0059] Table 1 is the parameter definition table.

[0060]

[0061]

[0062] Please see Figures 1 to 6 The specific plan is as follows:

[0063] A first embodiment provides a method for dead reckoning of an underwater glider, comprising the following steps:

[0064] S1. Obtain basic data, including the attitude angle, heading angle, depth data, marine environmental parameters, ocean current speed, dynamic pressure, and the glider's position information when it is on the water surface at different times; specifically:

[0065] Attitude angles (pitch angle θ, roll angle) can be directly obtained using high-precision attitude sensors. ) and heading angle The attitude and heading sensor should possess high stability and low noise characteristics, and its measurement accuracy should meet the requirements of underwater gliders for attitude and heading measurement under complex motion conditions. When installing the attitude and heading sensor, it must be precisely installed in a suitable location inside the underwater glider to ensure accurate measurement of attitude changes. After installation, the attitude and heading sensor should be rigorously calibrated using professional calibration equipment to eliminate measurement deviations caused by the installation process or the sensor itself.

[0066] A high-precision pressure sensor is used to acquire depth information for an underwater glider. The pressure sensor should have high resolution and good linearity, capable of accurately measuring changes in water pressure experienced by the glider at different depths and converting this into accurate depth data. The pressure sensor is installed in a location unaffected by water flow and capable of accurately reflecting changes in the glider's depth. Rigorous accuracy testing is required before installation, and regular calibration is necessary after installation to ensure the accuracy and reliability of depth measurements.

[0067] The marine environmental parameters mainly include seawater density and seawater temperature, which are collected by density sensors and temperature sensors.

[0068] Ocean current velocity is collected using a current velocity sensor;

[0069] Dynamic pressure is collected by a pressure sensor;

[0070] The glider's position information while on the water surface is obtained through the Global Positioning System (GPS) or the BeiDou Navigation Satellite System. When the underwater glider is on the surface, its initial position information (x0, y0, z0) is acquired via GPS or BeiDou. The positioning system should possess rapid and high-precision positioning capabilities, enabling it to obtain accurate position coordinates within a short time after the glider surfaces. Simultaneously, the timestamp of the position information acquisition is recorded for subsequent calculation of surface drift error.

[0071] S2. Position estimation using gliding inclination; specifically including:

[0072] S201. Calculate the vertical velocity of the underwater glider based on the rate of change of depth data;

[0073] The initial velocity v0 = 0 is set, and the initial position (x0, y0, z0) is determined by the surface GPS or BeiDou positioning system. Precise attitude and heading angles obtained from the attitude sensors are used for initialization to ensure the glider has accurate initial attitude and heading information when dead reckoning begins.

[0074] Based on the depth change rate measured by the pressure sensor Calculate the vertical velocity v z .

[0075] S202. Construct the mathematical relationship between vertical velocity and marine environmental parameters;

[0076] Real-time marine environmental parameters (such as seawater density ρ) are incorporated to optimize the gliding slope calculation. Dynamic pressure q and vertical velocity v are also considered. z The relationship is:

[0077]

[0078] S203. Calculate the gliding slope using the mathematical relationship and the glider dynamics equation;

[0079] The glider's dynamic equations are:

[0080] (ql 2 ) 2 bq -(1 / 4) -Bql 2 sin(γ)+B 2 cα -2 cos 2 (γ)=0

[0081] cα 2 +aαtan(γ)+bq -(1 / 4) =0

[0082] Where a, b, and c are hydrodynamic coefficients, l is the glider length, B is buoyancy, and α is the angle of attack.

[0083] Then combine the relationship between pitch angle, glide angle, and angle of attack:

[0084] γ=θ-α

[0085] The glide angle γ can be solved iteratively.

[0086] The gliding slope is tanγ.

[0087] S204. Calculate the eastward and northward horizontal velocity components by using the gliding slope and vertical velocity, combined with the heading angle.

[0088] Using the gliding angle γ and vertical velocity v z Calculate the eastward horizontal velocity component v by combining the heading angle. x The expression is:

[0089] Using the gliding angle γ and vertical velocity v z Calculate the northward horizontal velocity component v by combining the heading angle. y The expression is:

[0090] S205. Based on the eastward and northward horizontal velocity components, calculate the position increment and update the position using a precise integration algorithm;

[0091] The expression for the position increment is: Δx = v x Δt; Δy = v y Δt;

[0092] The expression for updating the position is: x n+1 =x n +Δx;y n+1 =y n +Δy.

[0093] S3, Ocean Current Compensation; Uses ocean current velocity to correct and update position.

[0094] Install an electromagnetic current meter to measure the ocean current velocity v around the glider. current Decomposed into levels (v) current,x ,v current,y ) and vertical component v current,z .

[0095] For the horizontal component, a prediction model for ocean current impact based on VMD-LSTM neural network is established:

[0096] Δx current =f(v current,x ,…)

[0097] Δy current =g(v current,y ,…)

[0098] f and g are prediction functions. In dead reckoning, the influence of ocean currents is compensated for in real time.

[0099] x compensated =x calc +Δx current

[0100] y compensated =y calc +Δy current

[0101] For the vertical component, a buoyancy adjustment system and depth control algorithm are combined. Based on the magnitude of the vertical component of the ocean current, buoyancy is automatically adjusted to enable the glider to resist the influence of the ocean current in the vertical direction, maintain a stable depth, ensure accurate depth measurement, and indirectly improve the accuracy of dead reckoning.

[0102] The VMD-LSTM neural network prediction method used in this invention combines the advantages of VMD and LSTM. VMD is used to decompose the original time series to obtain multiple intrinsic mode functions (IMFs). Each IMF represents the components of the original signal at different frequencies and amplitudes, and has better local feature representation. These IMFs are used as input sequences, and an LSTM prediction model is constructed for each mode for learning and prediction, thereby improving the prediction performance of the model. The prediction results of each mode are then superimposed and reconstructed to obtain the ideal output value.

[0103] A second embodiment provides an underwater glider dead reckoning system for implementing the method of the first embodiment, the system comprising:

[0104] The basic data acquisition module includes the attitude angle, heading angle, depth data, marine environmental parameters, ocean current speed, dynamic pressure, and position information of the underwater glider at different times.

[0105] The position estimation module uses gliding inclination to estimate position; specifically, it includes:

[0106] Calculate the vertical velocity of the underwater glider based on the rate of change of depth data;

[0107] Establish the mathematical relationship between vertical velocity and marine environmental parameters;

[0108] The gliding slope is calculated using the aforementioned mathematical relationships and the glider dynamics equations.

[0109] The eastward and northward horizontal velocity components are calculated using the gliding slope and vertical velocity, combined with the heading angle.

[0110] The position increment is calculated using an integral algorithm based on the eastward and northward horizontal velocity components, and the position is updated based on the position increment.

[0111] The ocean current compensation module uses ocean current velocity to correct and update the position.

[0112] In this embodiment, sensor selection and installation:

[0113] When selecting a high-performance, accurate attitude sensor from the market, ensure it is installed near the underwater glider's center of gravity or in another location capable of accurately capturing changes in the glider's attitude. The installation process must strictly follow the manufacturer's installation guidelines to guarantee accuracy. After installation, the attitude sensor should be calibrated using professional calibration equipment and procedures. The calibration process must cover all measurement axes of the sensor to ensure the accuracy of attitude and heading angle measurements.

[0114] Select a high-precision, high-resolution pressure sensor and install it in a location on the glider that is not directly impacted by water currents and can accurately reflect depth changes, such as a suitable position on the bottom or side of the glider. Before installation, the pressure sensor should undergo comprehensive accuracy testing, including key indicators such as linearity, repeatability, and hysteresis, to ensure that the sensor performance meets standards. After installation, regular calibration should be performed. The calibration cycle should be determined based on the sensor's stability and the operating environment; it is generally recommended to perform calibration at regular intervals (such as once a month or after a mission cycle).

[0115] Select a high-resolution, highly sensitive electromagnetic current meter and install it at an appropriate location on the glider to ensure comprehensive measurement of ocean currents at different depths around the glider. During installation, care should be taken to avoid electromagnetic interference or physical obstruction from other equipment to ensure the accuracy of the current measurements.

[0116] For GPS or BeiDou satellite positioning systems, ensure that the receiving equipment has good signal reception capability and fast positioning performance, and install it on the top of the glider or other locations with good signal reception, while taking protective measures such as waterproofing and collision protection.

[0117] Data processing and model calculation

[0118] Optimize the sensor data acquisition frequency by dynamically adjusting it according to the underwater glider's motion state. When the glider is moving steadily, appropriately reduce the sensor data acquisition frequency to decrease data processing volume and energy consumption; when the glider is accelerating, turning, or in complex ocean current environments, or when its motion state changes significantly, increase the sensor data acquisition frequency to ensure timely capture of the glider's state changes and provide accurate data support for dead reckoning.

[0119] In gliding slope calculation, accurate marine environmental parameters are acquired in real time. These parameters can be obtained by measuring seawater temperature, salinity, and density using a temperature, salinity, and density sensor (CTD) carried by the glider, or through wireless data communication with nearby marine monitoring equipment such as buoys and seabed observation stations. These environmental parameters are then accurately applied to the gliding slope calculation model to improve the accuracy of the calculation. During velocity and position estimation, the velocity correction factor and integral algorithm parameters are adjusted appropriately based on the glider's actual hydrodynamic characteristics and motion state to ensure the accuracy of both velocity and position calculations.

[0120] Training the current compensation model should utilize a large amount of representative historical ocean current data, glider motion data, and corresponding dead reckoning error data. The training data should cover various scenarios, including different ocean regions, seasons, and current conditions, to improve the model's generalization ability. The training data should be updated regularly to allow the model to adapt to changes in the marine environment. In practical applications, real-time acquisition of current data measured by electromagnetic current meters is crucial, and this data should be accurately input into the current compensation model for calculation and compensation.

[0121] Performance evaluation and optimization

[0122] The underwater glider should be tested under various marine environmental conditions. The test area should cover different ocean depths, current intensities and directions, and ocean topography to simulate various scenarios of underwater gliders in actual marine operations and obtain comprehensive and accurate test data.

[0123] The dead reckoning results calculated by the method of this invention are compared with high-precision acoustic positioning systems or other reliable positioning reference systems. The comparison indicators include statistical indicators such as the mean, standard deviation, and maximum error of the position error. At the same time, the distribution of the error at different depths, positions, and motion states is analyzed, the causes of the error are analyzed in depth, and the performance advantages and disadvantages of the method of this invention are evaluated.

[0124] Based on the performance evaluation results, the algorithm parameters, sensor configuration, or data processing strategies can be adjusted accordingly. For example, if the current compensation effect in a certain area is found to be unsatisfactory, the parameters of the current compensation model can be further optimized or the training data for that area can be increased; if abnormal fluctuations are found in sensor data, the sensor installation can be checked for secureness and interference, and corresponding improvement measures can be taken; if the error correction model is found to be inaccurate in certain situations, the model structure can be adjusted or new feature inputs can be added to continuously optimize the dead reckoning method and improve the positioning accuracy and navigation reliability of the underwater glider.

[0125] Figure 6 Numerical simulation results of dead reckoning under two different conditions based on actual sea trial data are presented. Specific details are as follows:

[0126] Solid lines represent the calculated trajectory of the equipment without ocean current compensation. Dashed lines represent the calculated trajectory of the equipment considering real-time ocean current compensation. Square markers indicate the actual entry point of the equipment. Triangle markers indicate the actual exit point of the equipment. Diamond markers indicate the theoretical exit point calculated by the equipment without ocean current compensation. Star markers indicate the theoretical exit point calculated by the equipment with real-time ocean current compensation.

[0127] By comparing the actual entry and exit points with the theoretical exit points under two different conditions, it can be seen that the total navigation distance (distance from the actual entry point to the actual exit point) is 2281.39m. The distance from the actual entry point to the theoretical exit point calculated without current compensation is 159.63m, and the distance from the actual entry point to the theoretical exit point calculated with real-time current compensation is 6.5m. The errors in the calculated exit points under the two different conditions are 159.63m and 6.5m, with calculation accuracies of 93% and 99.7%, respectively. Therefore, real-time current compensation can significantly improve the accuracy of dead reckoning.

[0128] The system's working steps are as follows:

[0129] 1. Start the underwater glider, initialize the sensor and model parameters, and acquire various sensor data at the initial moment (including attitude angle, depth, GPS or BeiDou positioning information, etc.).

[0130] 2. Enter the main loop, at each time step:

[0131] (1) Collect the latest sensor data, including attitude angle and heading angle data from the attitude sensor, depth data from the pressure sensor, and ocean current data measured by the electromagnetic current meter (or GPS or Beidou positioning data if on the water surface).

[0132] (2) Calculate the gliding slope and velocity position based on the gliding slope model.

[0133] (3) Perform depth constraint checks and adjustments to ensure the accuracy of glider depth calculations.

[0134] (4) Apply the ocean current compensation mechanism to correct the position calculation results and offset the influence of ocean current on the glider's position.

[0135] (5) Record the current dead reckoning results.

[0136] 3. Continue the cycle until the diving mission is completed or the termination conditions are met.

[0137] The third embodiment is a computer program product, including a computer program that, when executed by a processor, implements the above-described underwater glider dead reckoning method.

[0138] Fourth embodiment: an information data processing terminal for an underwater glider dead reckoning method.

[0139] Fifth embodiment: A computer-readable storage medium including instructions that, when executed on a computer, cause the computer to perform the above-described underwater glider dead reckoning method.

[0140] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented, in whole or in part, as a computer program product, the computer program product includes one or more computer instructions. When the computer program instructions are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0141] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A method for dead reckoning of underwater gliders, characterized in that, include: S1. Acquire basic data, which includes the attitude angle, heading angle, depth data, marine environmental parameters, ocean current speed, dynamic pressure, and position information of the glider when it is on the water surface at different times. S2. Position estimation using gliding inclination; specifically including: S201. Calculate the vertical velocity of the underwater glider based on the rate of change of depth data; S202. Construct the mathematical relationship between vertical velocity and marine environmental parameters; S203. Calculate the gliding slope using the mathematical relationship and the glider dynamics equation; S204. Calculate the eastward and northward horizontal velocity components by using the gliding slope and vertical velocity, combined with the heading angle. S205. Based on the eastward and northward horizontal velocity components, calculate the position increment using an integration algorithm, and update the position based on the position increment; S3, Ocean Current Compensation; Uses ocean current velocity to correct and update position.

2. The underwater glider dead reckoning method according to claim 1, characterized in that, The attitude angles include pitch angle and roll angle.

3. The underwater glider dead reckoning method according to claim 1, characterized in that, The marine environmental parameters include seawater density and seawater temperature.

4. The underwater glider dead reckoning method according to claim 1, characterized in that: In S1, pressure data of the underwater glider is acquired using pressure sensors, and depth data is calculated based on the pressure data. In S202, the mathematical relation is expressed as follows: Where: q is dynamic pressure, v z ρ is the vertical velocity, ρ is the seawater density, and γ is the gliding angle.

5. The underwater glider dead reckoning method according to claim 4, characterized in that, The glider's dynamic equations are: (ql 2 ) 2 bq -(1 / 4) -Bql 2 sin(γ)+B 2 cα -2 cos 2 (γ)=0 cα 2 +aαtan(γ)+bq -(1 / 4) =0 Where a, b, c are hydrodynamic coefficients, l is the glider length, B is buoyancy, and α is the angle of attack; The relationship between pitch angle θ, glide angle γ, and angle of attack α is as follows: γ = θ - α; The glide angle γ can be solved iteratively. The gliding slope is tanγ.

6. The underwater glider dead reckoning method according to claim 5, characterized in that, Eastward horizontal velocity component v x The expression is: Northward horizontal velocity component v y The expression is: in, This refers to the heading angle; The expression for the position increment is: Δx = v x Δt; Δy = v y Δt; The expression for updating the position is: x n+1 =x n +Δx;y n+1 =y n +Δy.

7. The underwater glider dead reckoning method according to claim 6, characterized in that, In S3, the VMD-LSTM neural network is used for ocean current compensation; Measuring the ocean current speed v around the glider current Decomposed into levels (v) current,x ,v current,y ) and vertical component v current,z ; A VMD-LSTM neural network-based model for predicting ocean current impacts: Δx current =f(v current,x ,…); Δy current =g(x current,y ,…); f and g are prediction functions; in dead reckoning, the influence of ocean currents is compensated for in real time. x compensated =x calc +Δx current ; y compensated =y calc +Δy current 。 8. A dead reckoning system for underwater gliders, characterized in that, include: The basic data acquisition module includes the attitude angle, heading angle, depth data, marine environmental parameters, ocean current speed, dynamic pressure, and position information of the underwater glider at different times. The position estimation module uses gliding inclination to estimate position; specifically, it includes: Calculate the vertical velocity of the underwater glider based on the rate of change of depth data; Establish the mathematical relationship between vertical velocity and marine environmental parameters; The gliding slope is calculated using the aforementioned mathematical relationships and the glider dynamics equations. The eastward and northward horizontal velocity components are calculated using the gliding slope and vertical velocity, combined with the heading angle. The position increment is calculated using an integral algorithm based on the eastward and northward horizontal velocity components, and the position is updated based on the position increment. The ocean current compensation module uses ocean current velocity to correct and update the position.

9. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it is the underwater glider dead reckoning method according to any one of claims 1-7.

10. A computer-readable storage medium comprising instructions, when executed on a computer, causing the computer to perform the underwater glider dead reckoning method as described in any one of claims 1-7.

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