Underwater integrated positioning and speed measuring device and use method thereof

Abstract

The invention relates to an underwater integrated positioning and speed measuring device and a use method thereof, the underwater integrated positioning and speed measuring device comprises a head sensor assembly and a pressure-resistant electronic cabin, the head is integrated with an acoustic positioning transducer and an electromagnetic speed measuring sensor, and an underwater acoustic signal processing board, an electromagnetic signal processing board, a heading attitude sensor and a main control board are arranged in the electronic cabin. According to the invention, the ultra-short baseline acoustic positioning technology and the electromagnetic induction velocity measurement technology are fused, the water velocity is estimated online in real time by using a state estimation method, and the accurately measured water velocity is converted into the ground velocity, so that the real-time measurement of the carrier position and the ground velocity is realized. The device can be used immediately after being powered on, does not need initial alignment, solves the problems that a traditional acoustic Doppler log is limited in ground velocity measurement acting distance, acoustic equipment interferes with each other and an inertial navigation system is slow to start, and realizes high-precision and high-reliability integrated positioning and velocity measurement of middle-layer and open sea underwater navigation bodies.

Description

Technical Field

[0001] This invention relates to the field of underwater positioning and speed measuring devices, and in particular to an integrated underwater positioning and speed measuring device and its usage method. Background Technology

[0002] Precise underwater positioning and velocity measurement are crucial for underwater vehicles to complete their underwater navigation and operational tasks. Currently, precise underwater positioning mainly relies on acoustic positioning systems (such as ultra-short baseline positioning systems), while precise ground velocity measurement primarily relies on acoustic Doppler logs. Furthermore, combining acoustic positioning systems, acoustic Doppler logs, and inertial navigation equipment can achieve even higher positioning and velocity measurement accuracy.

[0003] However, existing technologies mainly suffer from the following three problems: First, acoustic Doppler logs have a limited effective range for measuring ground velocity. For underwater vehicles in the mid-water zone, the platform is far from the seabed, exceeding the effective range, thus making it impossible to obtain accurate ground velocity information. Second, acoustic Doppler logs and acoustic positioning systems are both sonar devices, and there may be acoustic signal interference between them. Third, inertial navigation equipment has a relatively long initial alignment process during use, during which there are certain requirements for the motion state of the carrier platform (usually the carrier needs to remain stationary). Therefore, the equipment cannot immediately enter the navigation state after being powered on, and cannot immediately obtain navigation parameters such as the carrier's position, speed, and attitude. Power failure of the equipment may have a significant impact on the carrier platform's operation tasks.

[0004] Therefore, there is an urgent need for a new device and method that is suitable for mid-level waters, can overcome the above-mentioned technical defects, and can achieve high precision, high reliability, and integrated real-time positioning and velocity measurement. Summary of the Invention

[0005] To address the shortcomings of existing production technologies, the applicant provides an integrated underwater positioning and velocity measuring device and its usage method. This device combines the electromagnetic velocity measurement principle with the ultra-short baseline positioning principle, utilizes optimal state estimation theory to simultaneously calculate the precise position and ground velocity information of the carrier platform, and can immediately acquire navigation parameter information after power-on. Furthermore, the device's ground velocity measurement is not limited by the distance from the seabed, and there is no acoustic interference problem between sonar devices.

[0006] The technical solution adopted in this invention is as follows: An underwater integrated positioning and speed measuring device includes a pressure-resistant electronic compartment. The pressure-resistant electronic compartment includes an electronic compartment body, the bottom of which is a base plate and the top of which is a cover plate. The interior of the electronic compartment body is arranged from top to bottom as follows: an attitude sensor, an electromagnetic signal processing board, an underwater acoustic signal processing board, a main control board, and a power module. The main control board is connected to the underwater acoustic signal processing board, the electromagnetic signal processing board and the attitude sensor respectively. It is used to receive absolute position information, water velocity information and attitude angle information, and to process the data through a preset information fusion algorithm to output navigation parameters including the carrier's longitude, latitude, ground velocity and attitude in real time. A head sensor assembly is installed on the top surface of the cover plate. The head sensor assembly includes a sound-transmitting shroud fixed to the top surface of the cover plate, a transmitting transducer, four receiving transducers, and two electromagnetic speed sensors.

[0007] Its further technical solution lies in: The electronic cabin body adopts a thin-walled cylindrical structure.

[0008] A watertight joint is provided at the bottom center of the base plate.

[0009] A connecting frame extends downward from the bottom of the base plate.

[0010] The sound-permeable air guide cover is made of rubber.

[0011] The transmitting transducer is positioned in the middle of the cover plate, and four receiving transducers are evenly distributed around the transmitting transducer to form a receiving array.

[0012] Two electromagnetic velocity sensors are used to measure the velocity of the carrier platform relative to the water.

[0013] The two electromagnetic speed sensors are a front electromagnetic speed sensor and a rear electromagnetic speed sensor, respectively. Their forward and backward directions are consistent with the bow and stern directions of the carrier platform. The front electromagnetic speed sensor is used to measure the forward speed of the carrier platform, and the rear electromagnetic speed sensor is used to measure the lateral speed of the carrier platform. The two electromagnetic speed sensors are arranged orthogonally to each other.

[0014] The main body of the electromagnetic speed sensor is retracted inside the sound-permeable baffle, while the two electrode terminals protrude from the baffle.

[0015] A method for using an integrated underwater positioning and speed measuring device includes the following operating procedures: The first step is to select a fixed location in the navigation area as the origin of the coordinate system, and take the east, north, and sky directions as the three axes of the coordinate system to establish a local navigation coordinate system. The second step is to establish a state equation model, incorporate the unknown water flow velocity into the state vector, and simultaneously perform state estimation along with the platform's position and velocity:

[0016] in, for k The state vectors at time points represent the eastward position of the platform, the northward position of the platform, the eastward velocity of the platform, the northward velocity of the platform, the eastward component of the water flow velocity, and the northward component of the water flow velocity, respectively. for k The noise vector of the state equation at time t, where F is the state transition matrix, is expressed as:

[0017] In the formula It is a 2-order identity matrix. It is a 2-order zero matrix. The system sampling time interval; The third step is to establish the observation equation model:

[0018] in, for k The observation vector at time moment consists of two parameters: the first two parameters represent the absolute position information of the carrier platform projected onto the local navigation coordinate system from the measurement results of the underwater acoustic signal processing board, and the last two parameters represent the water velocity information of the carrier platform obtained after measurement by the electromagnetic signal processing board. for k The observation equation noise vector at time t, where H is the observation matrix, is expressed as:

[0019] In the formula It is a second-order rotation matrix, representing the rotation matrix from the vehicle coordinate system to the local navigation coordinate system. The rotation angle is obtained by the attitude sensor. Fourth, the robust Kalman filter method is used to calculate the state vector in real time, and the estimated values ​​of the eastward position, northward position, eastward velocity, and northward velocity of the carrier platform are obtained. Then, the eastward position and northward position are converted into longitude and latitude parameter information in the geodetic coordinate system through coordinate transformation.

[0020] The beneficial effects of this invention are as follows: (1) The present invention has highly integrated functions and a compact and reliable structure: This invention creatively integrates an ultra-short baseline acoustic positioning module and an electromagnetic velocity measurement module into a single device. By sharing a sound-transparent shroud, power supply, main control, and signal processing unit, it achieves an integrated design of "positioning-velocity measurement-information fusion." This effectively solves the problems of system complexity, large size, cumbersome installation, and high power consumption inherent in traditional multi-device combination schemes, significantly improving the system's structural stability, environmental adaptability, and engineering applicability, especially suitable for space-constrained underwater vehicle platforms.

[0021] (2) This invention fundamentally eliminates co-frequency interference between acoustic devices: This invention employs an "acoustic positioning combined with electromagnetic velocity measurement" approach, shifting the velocity measurement method from the acoustic domain to the electromagnetic domain. The two measurement methods operate on different physical principles and in completely isolated frequency bands, thus fundamentally avoiding the problem of interference from acoustic signals of the same or different frequencies that is difficult to overcome in traditional "acoustic positioning combined with Doppler velocity measurement" schemes. This ensures the independence and high reliability of positioning and velocity measurement data, and improves the system's operational stability in complex acoustic environments.

[0022] (3) This invention achieves "ready to use immediately", greatly improving task response capabilities: Unlike inertial navigation systems (INS), this invention eliminates the need for lengthy initial alignment. Upon power-up, the device immediately outputs effective navigation parameters based on raw acoustic positioning and electromagnetic velocity measurements via an information fusion algorithm. This enables underwater vehicles to deploy rapidly and be immediately deployed for missions. Furthermore, if the device restarts after a power outage during a mission, navigation can be restored without waiting, significantly enhancing the continuity and fault tolerance of mission execution.

[0023] (4) This invention achieves accurate ground velocity calculation by estimating water flow velocity online: This invention does not simply treat water velocity as ground velocity, but rather establishes a state-space model that includes water flow velocity components and employs robust optimal estimation algorithms (such as Kalman filtering) to estimate dynamically changing water flow velocity online in real time. This allows for the accurate conversion of precisely measured "water velocity" into more navigationally valuable "ground velocity," solving the problem of decreased navigation accuracy in mid-water areas where ground velocity cannot be directly measured.

[0024] (5) This invention has excellent anti-interference and anti-outlier capabilities, and its output is stable and reliable: To address the issue of underwater acoustic measurements being susceptible to environmental influences and potential outliers, this invention recommends and can employ advanced robust estimation algorithms, such as maximum correlation entropy Kalman filtering and robust Student t-distribution Kalman filtering, in the core information fusion algorithm. These algorithms effectively suppress non-Gaussian noise and outliers in the observation data, effectively smoothing disturbances caused by anomalous measurements and ensuring that the final output position and velocity information is more accurate, smooth, and reliable.

[0025] (6) This invention reduces the overall system cost and maintenance complexity: The integrated design reduces the number of sensors, cables, and interfaces, lowering system hardware, installation, and maintenance costs. Simultaneously, the unified software processing and external interfaces simplify user operation and integration, facilitating the widespread application of this technology.

[0026] In summary, this invention provides an innovative, high-performance integrated underwater navigation solution with outstanding comprehensive advantages in terms of functionality, applicability, reliability, real-time performance, and economy. It is particularly suitable for underwater navigation missions in mid-water areas with high navigation performance requirements. Attached Figure Description

[0027] Figure 1 This is the front view of the present invention.

[0028] Figure 2 This is a schematic diagram of the internal structure of the present invention.

[0029] Figure 3 This is a schematic diagram of the structure of the present invention (the sound-permeable flow guide hood is omitted).

[0030] Figure 4 This is a structural schematic diagram from another perspective of the present invention (the sound-permeable flow guide hood is omitted).

[0031] Figure 5 This is a diagram illustrating the application scenario of the present invention (I).

[0032] Figure 6 This is a diagram illustrating the application scenario of the present invention (II).

[0033] The components include: 1. Acoustic-transparent fairing; 2. Head sensor assembly; 3. Cover plate; 4. Electronics compartment body; 5. Base plate; 6. Connector; 7. Connecting frame; 8. Attitude and bearing sensor; 9. Electromagnetic signal processing board; 10. Underwater acoustic signal processing board; 11. Main control board; 12. Power module. 201. Receiving transducer; 202. Transmitting transducer; 203. Rear electromagnetic speed sensor; 204. Front electromagnetic speed sensor. Detailed Implementation

[0034] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0035] like Figures 1-6 As shown, the underwater integrated positioning and speed measuring device of this embodiment includes a pressure-resistant electronic compartment, which includes an electronic compartment body 4. The bottom of the electronic compartment body 4 is a bottom plate 5, and the top of the electronic compartment body 4 is a cover plate 3. The interior of the electronic compartment body 4 is arranged from top to bottom as follows: attitude sensor 8, electromagnetic signal processing board 9, underwater acoustic signal processing board 10, main control board 11, and power module 12. The main control board 11 is connected to the underwater acoustic signal processing board 10, the electromagnetic signal processing board 9 and the attitude sensor 8 respectively. It is used to receive absolute position information, water velocity information and attitude angle information, and to process the data through a preset information fusion algorithm to output navigation parameters including the longitude, latitude, ground velocity and attitude of the carrier in real time. A head sensor assembly 2 is installed on the top surface of the cover plate 3. The head sensor assembly 2 includes a sound-transmitting hood 1 fixed on the top surface of the cover plate 3, a transmitting transducer 202, four receiving transducers 201 and two electromagnetic speed sensors.

[0036] The electronic compartment hull 4 adopts a thin-walled cylindrical structure.

[0037] A watertight connector 6 is provided at the bottom center of the base plate 5.

[0038] A connecting frame 7 extends downward from the bottom of the base plate 5.

[0039] The sound-permeable airflow deflector 1 is made of rubber.

[0040] The transmitting transducer 202 is arranged in the middle of the cover plate 3, and four receiving transducers 201 are evenly distributed around the transmitting transducer 202 to form a receiving array.

[0041] Two electromagnetic velocity sensors are used to measure the velocity of the carrier platform relative to the water.

[0042] The two electromagnetic speed sensors are a front electromagnetic speed sensor 204 and a rear electromagnetic speed sensor 203. Their forward and backward directions are consistent with the bow and stern directions of the carrier platform. The front electromagnetic speed sensor 204 is used to measure the forward speed of the carrier platform, and the rear electromagnetic speed sensor 203 is used to measure the lateral speed of the carrier platform. The two electromagnetic speed sensors are arranged orthogonally to each other.

[0043] The main body of the electromagnetic speed sensor is retracted inside the sound-permeable shroud 1, while the two electrode terminals are exposed outside the sound-permeable shroud 1.

[0044] The specific structure and function of the underwater integrated positioning and speed measuring device described in this invention are as follows: It mainly includes a head sensor assembly 2, which consists of a sound-transparent shroud 1, a transmitting transducer 202, four receiving transducers 201, and two electromagnetic speed sensors (a front electromagnetic speed sensor 204 and a rear electromagnetic speed sensor 203). The four receiving transducers 201 and the two electromagnetic speed sensors have a hexagonal structure.

[0045] Among them, the sound-transmitting flow guide 1 is made of rubber. It serves two purposes: first, to allow sound waves to pass through and facilitate their effective transmission; and second, to stabilize the flow field and facilitate accurate speed measurement by the electromagnetic speed sensor.

[0046] Among them, the transmitting transducer 202 is based on the piezoelectric effect and is used to convert electrical signals into sound signals, which are then propagated to the outside world in the form of sound waves.

[0047] Among them, the receiving transducer 201 is also based on the piezoelectric effect and is used to convert the acoustic signal into an electrical signal. The four receiving transducers 201 are evenly distributed around the transmitting transducer 202 to form a receiving array.

[0048] Two electromagnetic velocity sensors are used to measure the velocity of the platform relative to the water. These sensors are arranged one in front of the other, with their forward and backward orientation aligned with the bow and stern of the platform. The forward electromagnetic velocity sensor 204 measures the forward velocity of the platform, while the rear electromagnetic velocity sensor 203 measures the lateral velocity. The two sensors are arranged orthogonally to each other. The main body of the electromagnetic velocity sensors is retracted inside the flow guide, while the two electrode terminals protrude from the flow guide.

[0049] It also includes a pressure-resistant electronic compartment, which consists of an electronic compartment body 4, a power module 12, a main control board 11, an underwater acoustic signal processing board 10, an electromagnetic signal processing board 9, and an attitude sensor 8.

[0050] The electronics compartment 4 mainly consists of a base plate 5 at the flange end of the device, a cover plate 3 on the top surface of the device, and the electronics compartment walls. The cover plate 3 is used for sealing and pressure resistance of the electronics compartment end face, and provides external installation and electrical interfaces for the entire device. The cover plate 3 also serves for sealing and pressure resistance of the electronics compartment end face, and simultaneously provides mounting brackets for the head sensor assembly 2. The electronics compartment walls are primarily used for pressure resistance of the electronics compartment.

[0051] The power module 12 is used to filter and convert external power to provide power to various electrical components of the device. This module is the external power supply interface of this device.

[0052] The main control board 11 is primarily used to read two types of position data from the underwater acoustic signal processing board 10, the water velocity data from the electromagnetic signal processing board 9, and the attitude parameters from the attitude sensor 8. It then combines the attitude parameters with the positioning and velocity data for information fusion processing, ultimately outputting the carrier platform's navigation parameters in the geodetic coordinate system, including longitude, latitude, eastward velocity, northward velocity, and attitude parameters. This board serves as the external communication interface for this device.

[0053] The underwater acoustic signal processing board 10 generates the excitation electrical signal for the transmitting transducer 202 and measures the voltage signal from the receiving transducer 201. After signal processing, it performs two tasks: first, it extracts the absolute position parameters of the beacon transmitted from the external beacon; second, it calculates the relative position parameters of the platform relative to the beacon based on the principle of ultra-short baseline positioning. Then, combined with the current attitude parameters, it calculates the absolute position parameters of the platform based on the principle of vector superposition. Finally, it sends the absolute position parameters of the platform to the main control board 11. The principle of ultra-short baseline positioning can be found in the paper "Ultra-short baseline positioning technology and its application in marine engineering" (Jin Bonan, Navigation, Positioning and Timing, 2018).

[0054] The electromagnetic signal processing board 9 is used to generate the excitation signal of the electromagnetic speed sensor and to measure the voltage signal from the electromagnetic speed sensor. After signal processing, it calculates the precise water velocity parameters of the carrier platform based on the principle of electromagnetic induction speed measurement and finally sends them to the main control board 11. The principle of electromagnetic induction speed measurement can be found in the book "Introduction to Navigation" (Bian Hongwei, Science Press, 2023).

[0055] The attitude sensor 8 is used to measure the heading angle, pitch angle and roll angle parameters of the carrier platform, and then sends the information to the main control board 11.

[0056] In practice, information fusion processing methods are adopted.

[0057] Main idea: Establish a state equation model and an observation equation model, add the unknown water flow velocity into the state vector, and use the optimal state estimation theory to estimate the longitude, latitude, eastward velocity, and northward velocity of the carrier platform in real time.

[0058] Specifically: First, select a fixed location in the navigation area as the origin of the coordinate system, and take the east, north, and sky directions as the three axes of the coordinate system to establish a local navigation coordinate system.

[0059] Second, establish a state equation model, incorporate the unknown water flow velocity into the state vector, and simultaneously perform state estimation along with the platform's position and velocity:

[0060] in, for k The state vectors at time points represent the eastward position of the platform, the northward position of the platform, the eastward velocity of the platform, the northward velocity of the platform, the eastward component of the water flow velocity, and the northward component of the water flow velocity, respectively. for k The state equation noise vector at time step (modeled as a white noise process with zero mean and variance Q), and F is the state transition matrix, expressed as:

[0061] In the formula It is a 2-order identity matrix. It is a 2-order zero matrix. This represents the system sampling time interval.

[0062] Third, establish the observation equation model:

[0063] in, for k The observation vector at time moment consists of two parameters: the first two parameters represent the absolute position information of the carrier platform projected onto the local navigation coordinate system from the measurement results of the underwater acoustic signal processing board, and the last two parameters represent the water velocity information of the carrier platform obtained after measurement by the electromagnetic signal processing board. for k The observation equation noise vector at time (modeled as a white noise process with zero mean and variance R), and H is the observation matrix, are expressed as:

[0064] In the formula It is a second-order rotation matrix, representing the rotation matrix from the vehicle coordinate system to the local navigation coordinate system. The rotation angle is obtained by the attitude sensor.

[0065] Fourth, robust Kalman filtering methods (such as maximum correlation entropy Kalman filtering, robust student t-Kalman filtering, etc.) are used to calculate the state vector in real time, and obtain the estimated values ​​of the eastward position, northward position, eastward velocity, and northward velocity of the carrier platform. Then, the eastward position and northward position are converted into longitude and latitude parameter information in the geodetic coordinate system through coordinate transformation.

[0066] Generally, this device needs to be used in conjunction with a beacon. The device is positioned on top of the carrier platform, while the beacon is positioned at the bottom of a surface buoy. The device and the beacon communicate and locate each other via wireless acoustic signals. Specifically, when the carrier platform is navigating underwater, the device first sends an acoustic signal to the beacon, which then responds and simultaneously transmits its own position information (obtained by the buoy via satellite navigation) to the device. The device can then calculate its absolute position in real time. Simultaneously, the device can accurately measure its velocity relative to the water using an electromagnetic induction sensor. Finally, based on the absolute position information and the accurate velocity relative to the water, the device uses an information fusion processing method to estimate the current velocity in real time, thereby calculating the precise velocity of the carrier platform relative to the ground, achieving precise underwater positioning and velocity measurement of the carrier platform.

[0067] This invention adopts a functional integration design: positioning and speed measurement functions are integrated into one device, which can simultaneously complete the accurate measurement of the absolute position of the carrier platform and the speed of the water.

[0068] This invention provides precise ground velocity estimation: by applying optimal state estimation theory, the unknown water flow velocity is added to the state vector for online estimation, thereby transforming precise water velocity information into precise ground velocity information, realizing information fusion processing, and obtaining precise ground velocity information of the carrier platform.

[0069] The invention's anti-interference capability: It proposes to use a robust Kalman filter method for state estimation, which is insensitive to acoustic measurement outliers, and the final obtained position and ground velocity are more accurate. This information fusion processing method has a certain anti-outlier interference capability.

[0070] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. An integrated underwater positioning and speed measuring device, characterized in that: The system includes a pressure-resistant electronic compartment, which includes an electronic compartment body (4), a bottom plate (5) at the bottom of the electronic compartment body (4), a cover plate (3) at the top of the electronic compartment body (4), and an attitude sensor (8), an electromagnetic signal processing board (9), an underwater acoustic signal processing board (10), a main control board (11), and a power module (12) arranged sequentially from top to bottom inside the electronic compartment body (4). The main control board (11) is connected to the underwater acoustic signal processing board (10), the electromagnetic signal processing board (9) and the attitude sensor (8) respectively. It is used to receive absolute position information, water velocity information and attitude angle information, and to process the data through a preset information fusion algorithm, and output navigation parameters including the longitude, latitude, ground velocity and attitude of the carrier in real time. A head sensor assembly (2) is installed on the top surface of the cover plate (3). The head sensor assembly (2) includes a sound-transmitting shroud (1) fixed on the top surface of the cover plate (3), a transmitting transducer (202), four receiving transducers (201) and two electromagnetic speed sensors.

2. The underwater integrated positioning and speed measuring device as described in claim 1, characterized in that: The electronic cabin body (4) adopts a thin-walled cylindrical structure.

3. The underwater integrated positioning and speed measuring device as described in claim 1, characterized in that: A watertight connector (6) is provided at the bottom center of the base plate (5).

4. The underwater integrated positioning and speed measuring device as described in claim 1, characterized in that: The bottom of the base plate (5) also extends downwards with a connecting frame (7).

5. The underwater integrated positioning and speed measuring device as described in claim 1, characterized in that: The sound-permeable air guide shroud (1) is made of rubber.

6. The underwater integrated positioning and speed measuring device as described in claim 1, characterized in that: The transmitting transducer (202) is arranged in the middle of the cover plate (3), and four receiving transducers (201) are evenly distributed around the transmitting transducer (202) to form a receiving array.

7. The underwater integrated positioning and speed measuring device as described in claim 1, characterized in that: Two electromagnetic velocity sensors are used to measure the velocity of the carrier platform relative to the water.

8. The underwater integrated positioning and speed measuring device as described in claim 1, characterized in that: The two electromagnetic speed sensors are a front electromagnetic speed sensor (204) and a rear electromagnetic speed sensor (203), respectively. The front and rear directions are consistent with the bow and stern directions of the carrier platform. The front electromagnetic speed sensor (204) is used to measure the forward speed of the carrier platform, and the rear electromagnetic speed sensor (203) is used to measure the lateral speed of the carrier platform. The two electromagnetic speed sensors are arranged orthogonally to each other.

9. The underwater integrated positioning and speed measuring device as described in claim 8, characterized in that: The main body of the electromagnetic speed sensor is retracted inside the sound-permeable shroud (1), while the two electrode terminals are exposed outside the sound-permeable shroud (1).

10. A method of using the underwater integrated positioning and speed measuring device as described in claim 1, characterized in that: The following operational procedures are included: The first step is to select a fixed location in the navigation area as the origin of the coordinate system, and take the east, north, and sky directions as the three axes of the coordinate system to establish a local navigation coordinate system. The second step is to establish a state equation model, incorporate the unknown water flow velocity into the state vector, and simultaneously perform state estimation along with the platform's position and velocity: in, for k The state vectors at time points represent the eastward position of the platform, the northward position of the platform, the eastward velocity of the platform, the northward velocity of the platform, the eastward component of the water flow velocity, and the northward component of the water flow velocity, respectively. for k The noise vector of the state equation at time t, where F is the state transition matrix, is expressed as: In the formula It is a 2-order identity matrix. It is a 2-order zero matrix. The system sampling time interval; The third step is to establish the observation equation model: in, for k The observation vector at time moment consists of two parameters: the first two parameters represent the absolute position information of the carrier platform projected onto the local navigation coordinate system from the measurement results of the underwater acoustic signal processing board, and the last two parameters represent the water velocity information of the carrier platform obtained after measurement by the electromagnetic signal processing board. for k The observation equation noise vector at time t, where H is the observation matrix, is expressed as: In the formula It is a second-order rotation matrix, representing the rotation matrix from the vehicle coordinate system to the local navigation coordinate system. The rotation angle is obtained by the attitude sensor. Fourth, the robust Kalman filter method is used to calculate the state vector in real time, and the estimated values ​​of the eastward position, northward position, eastward velocity, and northward velocity of the carrier platform are obtained. Then, the eastward position and northward position are converted into longitude and latitude parameter information in the geodetic coordinate system through coordinate transformation.

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