A method and system for high-precision measurement of underwater magnetic field

Abstract

This invention discloses a high-precision underwater magnetic field measurement method and system. The system includes an underwater measurement subsystem, an underwater relay subsystem, a central control subsystem, and a base station positioning subsystem. The measurement subsystem is mounted on a first UUV, and the relay subsystem is mounted on a second UUV. Both the first and second UUVs navigate along a magnetic field measurement trajectory. The measurement subsystem measures underwater magnetic field information and transmits it to the control subsystem, which processes the magnetic field information. During the magnetic field measurement process, the relay subsystem performs attitude calibration on the first UUV, while the measurement subsystem performs attitude calibration on the second UUV. This application eliminates the need for a fixed underwater magnetic field measurement site. By cooperating with multiple subsystems, underwater magnetic field detection is achieved, ensuring the positioning accuracy and measurement accuracy of the magnetic measurement instrument, improving the efficiency of magnetic field detection, and enabling underwater magnetic field detection even during long voyages.

Description

Technical Field

[0001] This invention relates to the field of magnetic field measurement technology, and in particular to a high-precision underwater magnetic field measurement method and system. Background Technology

[0002] Currently, there are two main approaches to underwater magnetic field measurement. One approach involves deploying a magnetic field measuring device in a fixed underwater environment to directly measure the underwater magnetic field. The other involves deploying the device on a vessel, which then navigates within a designated measurement area to complete the measurement. Underwater magnetic field measurement demands extremely high positioning accuracy from the measuring device, typically within one meter. When using the first method, the measurement accuracy is easily affected by water flow speed or underwater depth, leading to low accuracy. When using the second method, the vessel carrying the measuring device has significant inertia, making vessel control extremely difficult, resulting in low measurement efficiency and making it impossible to perform magnetic field measurements during long voyages. Summary of the Invention

[0003] The purpose of this invention is to provide a simple and highly maneuverable method and system for measuring underwater magnetic fields with high precision. Through the autonomous and intelligent cooperation of each subsystem, the underwater magnetic field can be measured autonomously and accurately. The method is simple to operate, highly maneuverable, and can effectively improve the measurement accuracy of underwater magnetic fields.

[0004] The solution to the technical problem of this invention is as follows: Firstly, this application provides a high-precision underwater magnetic field measurement method, applied to an underwater magnetic field high-precision measurement system, the system comprising:

[0005] A first UUV and a second UUV are connected by an optical fiber. Both the first UUV and the second UUV travel along a magnetic field measurement trajectory. The magnetic field measurement trajectory is set with i magnetic field measurement positions and i corresponding magnetic field measurement sub-positions, where i = 1, 2, 3, ..., n.

[0006] An underwater measurement subsystem, mounted on the first UUV, communicates in real time with the underwater relay subsystem.

[0007] The underwater relay subsystem is mounted on the second UUV;

[0008] The central control subsystem communicates in real time with the underwater relay subsystem.

[0009] Includes the following steps:

[0010] The second UUV remains stationary, while the first UUV navigates toward the i-th magnetic field measurement position. The underwater measurement subsystem transmits a second high-frequency sonar signal, and the underwater relay subsystem performs attitude calibration on the first UUV based on the transmission and arrival times of the second high-frequency sonar signal to ensure that the first UUV can reach the i-th magnetic field measurement position.

[0011] When the first UUV reaches the i-th magnetic field measurement position, the first UUV stops sailing, and the underwater measurement subsystem measures the underwater magnetic field and outputs the magnetic field measurement information to the underwater relay subsystem; where i = 1, 2, 3, ..., n;

[0012] When the first UUV reaches the i-th magnetic field measurement position, the second UUV sails to the i-th magnetic field measurement sub-position. During the sailing of the second UUV, the underwater measurement subsystem performs pose calibration on the second UUV based on the transmission and arrival times of the second high-frequency sonar signal.

[0013] Determine whether the underwater measurement subsystem has completed magnetic field measurements at all the magnetic field measurement locations;

[0014] If not, then let i = i + 1 and repeat the above steps;

[0015] If the underwater measurement subsystem completes magnetic field measurements at all the magnetic field measurement locations, then both the first UUV and the second UUV return to the starting position of the magnetic field measurement trajectory.

[0016] When the second UUV obtains the magnetic field measurement information, the underwater relay subsystem sends the magnetic field measurement information to the central control subsystem. The central control subsystem processes and calculates the magnetic field measurement information, outputs the calculation results, and displays them.

[0017] On the other hand, this application provides a high-precision underwater magnetic field measurement system, including: a base station positioning subsystem, an underwater measurement subsystem, an underwater relay subsystem, and a central control subsystem. The underwater measurement subsystem is mounted on a first UUV, and the underwater relay subsystem is mounted on a second UUV. The underwater relay subsystem communicates in real time with the underwater measurement subsystem and the central control subsystem, respectively.

[0018] The first UUV and the second UUV are connected by optical fiber, and both the first UUV and the second UUV travel along the magnetic field measurement trajectory;

[0019] The base station positioning subsystem includes:

[0020] A high-frequency sonar spotter is used to emit a first high-frequency sonar signal downward in a vertical direction. The first high-frequency sonar signal is used to locate the second UUV and ensure that the initial position of the second UUV is directly below the high-frequency sonar spotter.

[0021] A rigid telescopic rod, one end of which is fixed to the bow of the ship, and the other end of which is connected to the high-frequency sonar beam emitter;

[0022] The underwater measurement subsystem includes:

[0023] The first depth sensor is used to detect the water depth at the location of the first UUV;

[0024] A magnetic field measuring device is used to measure underwater magnetic fields and obtain magnetic field measurement information.

[0025] A first high-frequency sonar transducer and a second high-frequency sonar transducer are used to transmit a second high-frequency sonar signal; the first high-frequency sonar transducer and the second high-frequency sonar transducer are connected by a rigid body, the first high-frequency sonar transducer is fixed to one end of the first UUV, and the second high-frequency sonar transducer is fixed to the other end of the first UUV.

[0026] The first optical fiber communication device is used for real-time communication with the underwater relay subsystem;

[0027] A first embedded intelligent control device is used to record a second transmission time value and a second arrival time value. Based on the difference between the second transmission time value and the second arrival time value, it outputs a second pose calibration signal to the underwater relay subsystem through the first optical fiber communication device. The second pose calibration signal is used to control the second UUV to perform pose calibration.

[0028] The first embedded intelligent control device is also used to generate specific state information of the first UUV;

[0029] The second transmission time value is defined as the time value at which the underwater measurement subsystem transmits the second high-frequency sonar signal during the navigation of the second UUV;

[0030] The second arrival time value is defined as the time value at which the second high-frequency sonar signal arrives at the underwater relay subsystem during the second UUV's voyage.

[0031] The underwater relay subsystem includes:

[0032] The second depth sensor is used to detect the water depth at the location of the second UUV;

[0033] A hydrophone array comprising three hydrophones arranged in an equilateral triangle with the center of the second UUV as the center, wherein each hydrophone is used to receive the second high-frequency sonar signal.

[0034] The second optical fiber communication device is used to communicate with the first optical fiber communication device in real time.

[0035] The second embedded intelligent control device is used to record the first arrival time value and the first transmission time value, and outputs the first pose calibration signal through the second optical fiber communication device based on the difference between the first arrival time value and the first transmission time value. The first pose calibration signal is used to perform pose calibration on the first UUV.

[0036] Wherein, the first transmission time value is defined as the time value at which the underwater measurement subsystem transmits the second high-frequency sonar signal during the first UUV's navigation;

[0037] The first arrival time value is defined as the time when the second high-frequency sonar signal arrives at the underwater relay subsystem during the first UUV's voyage.

[0038] The second embedded intelligent control device is also used to generate specific state information of the second UUV;

[0039] A buoy communication device is used to output the magnetic field measurement information, the specific status information of the first UUV, and the specific status information of the second UUV to the central control subsystem.

[0040] The central control subsystem includes:

[0041] A radio communication device for real-time communication with the buoy communication device;

[0042] The host computer is used to process the magnetic field measurement information, the specific status information of the first UUV and the specific status information of the second UUV, output the processing results and display them on the human-computer interaction interface.

[0043] The beneficial effects of this invention are: it provides a high-precision underwater magnetic field measurement method and system. This method does not require the construction of a fixed underwater magnetic field measurement site, nor does it require human control. Through the cooperation of multiple subsystems, it can detect multiple areas of the underwater magnetic field, ensuring the positioning accuracy and measurement accuracy of the magnetic measuring instrument, improving the working efficiency of magnetic field detection, and enabling underwater magnetic field detection during long voyages. Attached Figure Description

[0044] Figure 1 A structural diagram of the high-precision underwater magnetic field measurement system provided in the embodiments of this application;

[0045] Figure 2 This is a structural diagram of the base station positioning subsystem provided in an embodiment of this application;

[0046] Figure 3 A schematic diagram of the underwater relay subsystem and the underwater measurement subsystem provided in the embodiments of this application;

[0047] Figure 4 A flowchart of the underwater magnetic field high-precision measurement method provided in the embodiments of this application;

[0048] Figure 5A A schematic diagram of a first application scenario for the high-precision underwater magnetic field measurement method provided in this application embodiment;

[0049] Figure 5B A schematic diagram of a second application scenario for the high-precision underwater magnetic field measurement method provided in the embodiments of this application;

[0050] Figure 5C This is a schematic diagram of a third application scenario for the high-precision underwater magnetic field measurement method provided in the embodiments of this application. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0052] The present application will be further described below with reference to the accompanying drawings and specific embodiments. The described embodiments should not be considered as limitations on the present application, and all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present application.

[0053] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0055] Before providing a further detailed description of the embodiments of this application, the nouns and terms involved in the embodiments of this application will be explained, and the nouns and terms involved in the embodiments of this application shall be interpreted as follows.

[0056] (1) UUV (underwater unmanned vehicle) refers to an underwater vehicle that does not require human piloting and performs navigation tasks underwater through autonomous or remote control means. It is mainly used for underwater environmental detection, rescue and other purposes. UUVs can carry a variety of sensors or marine-specific equipment and have the characteristics of autonomy, low risk, stealth, deployability and environmental adaptability.

[0057] It should be noted that the unmanned underwater vehicle mentioned in the following embodiments refers to UUV.

[0058] Currently, in this field, underwater magnetic field measurements are typically achieved by deploying a magnetic field measuring device in a fixed underwater area; or by deploying the device on a vessel and having the vessel move within a fixed measurement area as required to measure the underwater magnetic field. However, underwater magnetic field measurements require extremely high positioning accuracy for the measuring device, typically within one meter. When using the first method, the accuracy is easily affected by water flow speed or underwater depth, resulting in low measurement accuracy. When using the second method, the vessel carrying the measuring device has significant inertia during navigation, making it difficult to control and reducing measurement efficiency. Furthermore, neither of these methods can perform high-precision magnetic field measurements during long voyages.

[0059] To address the aforementioned technical problems in this field, such as low efficiency, high cost, and poor mobility in underwater magnetic field measurement, this application provides an underwater magnetic field measurement method and system. This method achieves coordinated measurement of the magnetic field in different areas through autonomous intelligent collaboration of multiple systems, reducing the accumulated positioning errors of magnetic measuring instruments and improving both positioning accuracy and work efficiency. Furthermore, this application eliminates the need for a fixed underwater magnetic field measurement site, improving the flexibility of magnetic measurement operations, reducing costs, and autonomously and efficiently achieving underwater magnetic field measurement without human control.

[0060] Reference Figure 1 As shown, Figure 1 The diagram shown is a structural diagram of the high-precision underwater magnetic field measurement system provided in an embodiment of this application. Before describing and elaborating on the high-precision underwater magnetic field measurement method provided in this application, the structure of the high-precision underwater magnetic field measurement system used in this method will be described first. This high-precision underwater magnetic field measurement system includes four subsystems, namely:

[0061] The underwater measurement subsystem is installed on the first unmanned submersible 100 and communicates in real time with the underwater relay subsystem.

[0062] It should be noted that the function of the measurement subsystem is to measure the underwater magnetic field at a certain depth, obtain magnetic field measurement information by measuring the magnetic field at a certain depth, and calibrate the position and attitude of the second unmanned submersible 200 during navigation.

[0063] The underwater relay subsystem is installed on the second unmanned submersible 200 and communicates in real time with the underwater measurement subsystem.

[0064] It should be noted that the relay subsystem is used to calibrate the position and attitude of the first unmanned submersible 100 at a certain underwater depth while it is navigating, so as to improve the accuracy of the magnetic field measurement information obtained by the measurement subsystem.

[0065] Furthermore, the relay subsystem also serves to receive magnetic field measurement information from the measurement subsystem and send it to the central control subsystem.

[0066] It should be noted that the two unmanned underwater vehicles (UUVs) in this application are connected via fiber optic cable 400 and both move along a magnetic field measurement trajectory. The magnetic field measurement trajectory has several magnetic field measurement positions and sub-positions, with a one-to-one correspondence between the measurement positions and sub-positions. When the first UUV 100 reaches a measurement position, it stops its navigation and begins magnetic field measurement, while the second UUV 200 navigates towards the sub-position. When the second UUV 200 reaches a sub-position, it stops its navigation, and the first UUV 100 stops magnetic field measurement and navigates towards the next measurement position. This cycle continues until the first UUV 100 completes its magnetic field measurement at the last measurement position.

[0067] The central control subsystem communicates in real time with the underwater relay subsystem. Its function is to receive information from the relay subsystem, analyze, process, and calculate the information to obtain relevant calculation results.

[0068] Optionally, the relevant calculation results are displayed on the human-machine interface of the control subsystem.

[0069] The base station positioning subsystem 300 is used to calibrate the position and attitude of the second unmanned submersible 200 during the descent of the first unmanned submersible 100 and the second unmanned submersible 200 to a certain underwater depth, so as to ensure that the position and attitude of the second unmanned submersible 200 are correct and improve the accuracy of magnetic field measurement.

[0070] Reference Figure 1 and Figure 2 As shown, Figure 2This is a structural diagram of a base station positioning subsystem 300 provided in an embodiment of this application. An embodiment of this application is described below, and the positioning subsystem 300 is further illustrated. The positioning subsystem 300 includes a rigid telescopic rod 310 and a high-frequency sonar beam emitter 320.

[0071] It should be noted that the function of the high-frequency sonar spotlight transmitter 320 is to emit high-frequency sonar signals downward in a vertical direction. The signal emitted by the high-frequency sonar spotlight transmitter 320 is referred to as the first high-frequency sonar signal.

[0072] Optionally, the high-frequency sonar beamforming transmitter 320 mainly consists of a sub-high-frequency sonar transducer and an acoustic beamforming device. The sub-high-frequency sonar transducer is a transducer that converts electrical signals into underwater acoustic signals to radiate sound waves into the water. It must withstand sufficient power, have high mechanical strength and high electroacoustic efficiency, and be easily matched with the transmitter. The acoustic beamforming device reduces the directional angle of the acoustic signal, thus focusing the acoustic signal onto the relay subsystem.

[0073] It should be noted that the rigid telescopic rod 310 is a rod that can extend and retract vertically. One end of it can be fixed at the bow of the vessel, while the end away from the bow is connected to the high-frequency sonar spotter 320. The function of the rigid telescopic rod 310 is to place the high-frequency sonar spotter 320 underwater. Here, "vehicle" refers to the vessel used by the user of this underwater magnetic field high-precision measurement system.

[0074] In this specific embodiment, the relay subsystem can calibrate the position and attitude of the second unmanned underwater vehicle (UUV) 200 using the high-frequency sonar signal emitted by the high-frequency sonar spotter 320, ensuring that the initial position of the second UUV 200 is directly below the high-frequency sonar spotter 320. The second UUV 200 is connected to the first UUV 100 via optical fiber 400. The accurately positioned second UUV 200 can adjust the position and attitude of the first UUV 100, thereby enabling the first UUV 100 to reach the magnetic field measurement trajectory. The positioning subsystem 300 provided in this application enables precise positioning of the two UUVs, ensuring that the second UUV 200 accurately reaches the starting position of the magnetic field measurement trajectory, with its initial position being the starting position of the magnetic field measurement trajectory. This provides a guarantee for high-precision magnetic field measurement.

[0075] Reference Figure 1 and Figure 3 As shown, Figure 3This is a schematic diagram of the underwater relay subsystem and underwater measurement subsystem provided in an embodiment of this application. In one embodiment of this application, the process by which the underwater measurement subsystem and the measurement subsystem jointly perform underwater magnetic field measurement and transmission of magnetic field measurement information will be further explained and elaborated below.

[0076] One of the functions of the measurement subsystem is to measure the underwater magnetic field and transmit the underwater magnetic field and related information of the first unmanned submersible 100 to the control subsystem via the relay subsystem. To this end, the measurement subsystem is equipped with a magnetic field measuring device 120 and a first fiber optic communication device. The measurement subsystem achieves underwater magnetic field measurement through the magnetic field measuring device 120 and the first fiber optic communication device.

[0077] Specifically, the function of the magnetic field measuring device 120 is to measure the underwater magnetic field and obtain magnetic field measurement information.

[0078] It should be noted that the magnetic field measuring device 120 is also called a magnetic measuring instrument. Magnetic measuring instruments are instruments used to measure magnetic quantities of macroscopic magnetic fields and magnetic materials. They are generally divided into two main categories according to the object being measured. The first type of instrument is used to measure physical quantities characterizing magnetic fields, such as magnetic field strength, magnetic flux density, magnetic flux, and magnetic moment. The second type of instrument is used to measure the properties of magnetic materials, such as magnetic permeability, magnetization, magnetization curve, hysteresis loop, and AC loss.

[0079] It should be noted that this application does not specifically limit the type of magnetic measuring instrument, which can be selected according to the actual situation. Therefore, this application also does not specifically limit the physical quantities of the magnetic field characteristics characterized by the measured magnetic field information, which are determined by the type of magnetic measuring instrument.

[0080] Optionally, when the first unmanned underwater vehicle 100 moves along the trajectory to the magnetic field measurement position, the magnetic field measurement device 120 starts measuring the underwater magnetic field information and obtains the magnetic field measurement information; when the second unmanned underwater vehicle 200 moves along the trajectory to the magnetic field measurement sub-position, the magnetic field measurement device 120 stops measuring the underwater magnetic field information.

[0081] It should be noted that the function of the first optical fiber communication device is to communicate with the relay subsystem in real time, that is, to transmit signals and information with the relay subsystem.

[0082] In this specific embodiment, since the first unmanned underwater vehicle 100 and the second unmanned underwater vehicle 200 are connected by an optical fiber 400, i.e., they communicate with each other via optical fiber, the magnetic field measurement information is transmitted in real time to the relay subsystem through the first and second optical fiber communication devices. Optical fiber communication has a wide bandwidth and large communication capacity, which can support the transmission of large amounts of data between the two unmanned underwater vehicles. Furthermore, optical fiber communication is resistant to electromagnetic interference and will not be affected by underwater magnetic fields during communication between the two unmanned underwater vehicles.

[0083] The relay subsystem is equipped with a second fiber optic communication device and a buoy communication device 500. The second fiber optic communication device communicates with the first fiber optic communication device, thereby enabling signal and information transmission between the relay subsystem and the measurement subsystem. The buoy communication device 500 enables data communication between the relay subsystem and the control subsystem.

[0084] In one embodiment, the first fiber optic communication device of the measurement subsystem transmits magnetic field measurement information to the second fiber optic communication device in real time, and the second fiber optic communication device transmits the magnetic field measurement information to the buoy communication device 500. The buoy communication device 500 then transmits the received magnetic field measurement information to the control subsystem for underwater magnetic field analysis.

[0085] Based on the above embodiments, since the first unmanned underwater vehicle 100 carries the measurement subsystem, its position and attitude significantly affect the accuracy of the magnetic field measurement of the measurement subsystem. If the position and attitude of the first unmanned underwater vehicle 100 are incorrect, it will prevent the first unmanned underwater vehicle 100 from accurately reaching the magnetic field measurement position, or cause errors in the angle at which the magnetic field measurement instrument it carries measures the magnetic field. Therefore, calibrating the position and attitude of the first unmanned underwater vehicle 100 is essential.

[0086] In this application, to reduce the impact of the position and attitude of the first unmanned underwater vehicle (UUV) 100 on the magnetic field measurement, ensure that the first UUV 100 maintains the correct position and attitude, and ensure that the first UUV 100 accurately reaches the magnetic field measurement position, during the process of the first UUV 100 moving to the magnetic field measurement position, the relay subsystem acquires the second high-frequency sonar signal sent by the measurement subsystem, and adjusts the position and attitude of the first UUV 100 in real time using the second high-frequency sonar signal. This ensures that the first UUV 100 can accurately reach the magnetic field measurement position, thereby ensuring the accuracy of the underwater magnetic field measurement.

[0087] In one embodiment of this application, the process of calibrating the position and attitude of the first unmanned submersible 100 by the underwater relay subsystem will be further explained and elaborated below.

[0088] The measurement subsystem is also equipped with a high-frequency sonar transducer group 110. The high-frequency sonar transducer group 110 is divided into a first high-frequency sonar transducer 111 and a second high-frequency sonar transducer 112. The function of the high-frequency sonar transducer group 110 is to emit high-frequency sonar signals, and the signal emitted by the high-frequency sonar transducer group 110 is denoted as the second high-frequency sonar signal.

[0089] Furthermore, the two high-frequency sonar transducers are connected together by a rigid body. One end of the rigid body is fixed with the first high-frequency sonar transducer 111, and the other end is fixed with the second high-frequency sonar transducer 112.

[0090] In this specific embodiment, as the first unmanned underwater vehicle 100 moves along the magnetic field measurement trajectory, the high-frequency sonar transducer array 110 continuously emits high-frequency sonar signals until the magnetic field measurement of the entire measurement trajectory is completed. In one embodiment, the high-frequency sonar signals emitted by the high-frequency sonar transducer array 110 are provided to the relay subsystem for calibrating the position and attitude of the first unmanned underwater vehicle 100. In another embodiment, the high-frequency sonar signals emitted by the high-frequency sonar transducer array 110 are also provided to the measurement subsystem for calibrating the position and attitude of the second unmanned underwater vehicle 200.

[0091] The relay subsystem is also equipped with a hydrophone array 210 and a second embedded intelligent control device. In this application, the hydrophone array 210, the second embedded intelligent control device, and the second fiber optic communication device of the relay subsystem work together to calibrate the position and attitude of the first unmanned underwater vehicle 100 during its navigation.

[0092] Specifically, the hydrophone array 210 is used to acquire a first high-frequency sonar signal and a second high-frequency sonar signal. The first high-frequency sonar signal is transmitted by the high-frequency sonar transducer group 110 of the base station positioning subsystem; the second high-frequency sonar signal is transmitted by the high-frequency sonar transducer group 110 of the measurement subsystem.

[0093] Optionally, the hydrophone array 210 consists of a first hydrophone 211, a second hydrophone 212, and a third hydrophone 213. The first hydrophone 211, the second hydrophone 212, and the third hydrophone 213 are arranged in an equilateral triangle with the center of the second unmanned underwater vehicle 200 as the center point. The purpose of the equilateral triangle is to measure the distance to the high-frequency sonar beam emitter 320. When any pair of the first hydrophone 211, the second hydrophone 212, and the third hydrophone 213 are equidistant, it indicates that the second unmanned underwater vehicle 200 is directly below the high-frequency sonar beam emitter 320.

[0094] It should be noted that a hydrophone is a transducer that converts sound signals into electrical signals. Its role in sonar is similar to that of an antenna in radio equipment, used to receive sound signals in water. Hydrophones are widely used in underwater communication, exploration, target location, and tracking. Optionally, the type of hydrophone can be a vector hydrophone or a fiber optic hydrophone.

[0095] Specifically, the function of the second embedded intelligent control device is to obtain the first transmission time value through the optical fiber communication device.

[0096] It should be noted that the first launch time value is defined as the time value at which the high-frequency sonar transducer group 110 of the measurement subsystem launches the second high-frequency sonar signal during the navigation of the first unmanned underwater vehicle 100.

[0097] Specifically, the second embedded intelligent control device also includes storing the first arrival time value, subtracting the first launch time value from the first arrival time value to obtain the first distance, and outputting the first attitude calibration signal to the underwater measurement subsystem through the first distance to calibrate the position and attitude of the first unmanned submersible 100.

[0098] It should be noted that the first arrival time value is defined as the time when the second high-frequency sonar signal arrives at the hydrophone array 210 of the underwater relay subsystem during the navigation of the first unmanned underwater vehicle 100.

[0099] It should be noted that the underwater relay subsystem transmits the first attitude calibration signal to the underwater measurement subsystem through the second optical fiber communication device.

[0100] In this specific embodiment, when the first unmanned underwater vehicle (UUV) 100 arrives at the magnetic field measurement location, the measurement subsystem performs magnetic field measurement. During the navigation of the first UUV 100, the hydrophone array 210 acquires the second high-frequency sonar signal emitted by the high-frequency sonar transducer group 110 of the measurement subsystem in real time; the second embedded intelligent control device receives the first transmission time value through the second fiber optic communication device; the second embedded intelligent control device records the first transmission time value and the first arrival time value. The second embedded intelligent control device processes and calculates the first transmission time value and the first arrival time value to obtain the current position information of the first UUV 100, that is, the distance between the first UUV 100 and the magnetic field measurement location. Subsequently, the second embedded intelligent control device calibrates the position and attitude of the first UUV 100 based on the distance between the first UUV 100 and the magnetic field measurement location to ensure that the position and attitude of the first UUV 100 are correct, reduce the influence of the position and attitude of the first UUV 100 on the magnetic field measurement device 120, and thus improve the accuracy of underwater magnetic field measurement.

[0101] Based on the above embodiments, this application uses a second unmanned underwater vehicle (UUV) 200 to calibrate the position and attitude of a first UUV 100. Therefore, the position and attitude of the second UUV 200 have a certain influence on the attitude calibration of the first UUV 100. If there is a deviation in the position and attitude of the second UUV 200, it may lead to calibration errors when calibrating the position and attitude of the first UUV 100, which in turn may lead to measurement errors when the magnetic measuring instrument measures the underwater magnetic field. Therefore, calibrating the position and attitude of the second UUV 200 is also very necessary. To reduce the influence of the position and attitude of the second UUV 200 on the attitude calibration of the first UUV 100, this application controls the high-frequency sonar transducer group 110 to continuously emit high-frequency sonar signals. Based on these high-frequency sonar signals, the measurement subsystem calibrates the position and attitude of the second UUV 200.

[0102] In one embodiment of this application, the process of calibrating the position and attitude of the second unmanned underwater vehicle 200 by the measurement subsystem will be further described and explained below. The measurement subsystem is also equipped with a first embedded intelligent control device.

[0103] Specifically, the first embedded intelligent control device obtains the second arrival time value through an optical fiber communication device.

[0104] It should be noted that the second arrival time value is defined as the time when the second high-frequency sonar signal arrives at the hydrophone array 210 of the underwater relay subsystem during the navigation of the second unmanned underwater vehicle 200.

[0105] The first embedded intelligent control device also includes: recording the second launch time value and the second arrival time value; subtracting the second launch time value and the second arrival time value to obtain the second distance; and outputting a second pose calibration signal to the relay subsystem through the second distance to calibrate the position and attitude of the second unmanned underwater vehicle 200.

[0106] It should be noted that the second launch time value is defined as the time value at which the measurement subsystem launches the second high-frequency sonar signal during the navigation of the second unmanned underwater vehicle 200.

[0107] It should be noted that the measurement subsystem transmits the second pose calibration signal to the relay subsystem through the first optical fiber communication device.

[0108] In this specific embodiment, during the process of the second unmanned underwater vehicle 200 navigating towards the first unmanned underwater vehicle 100, the measurement subsystem calibrates the position and attitude of the second unmanned underwater vehicle 200. The calibration of the position and attitude of the first unmanned underwater vehicle 100 is based on the calibration of the position and attitude of the second unmanned underwater vehicle 200. The position and attitude of the second unmanned underwater vehicle 200 will affect the second high-frequency sonar signal it receives, potentially causing errors in the received signal. This, in turn, leads to erroneous calibration of the attitude and position of the first unmanned underwater vehicle 100 by the relay subsystem. Therefore, it is necessary for the relay subsystem to calibrate the position and attitude of the second unmanned underwater vehicle 200 simultaneously with the calibration of the position and attitude of the first unmanned underwater vehicle 100.

[0109] In this application, the hydrophone array 210 of the relay subsystem acquires the second high-frequency sonar signal emitted by the high-frequency sonar transducer group 110 of the measurement subsystem in real time. The first embedded intelligent control device acquires the arrival time value of the second high-frequency sonar signal at the relay subsystem, i.e., the second arrival time value, through the first fiber optic communication device. The first embedded intelligent control device calculates the difference between the second arrival time value and the second emission time value to obtain the current position information of the second unmanned underwater vehicle 200, i.e., the distance between the second unmanned underwater vehicle 200 and the magnetic field measurement sub-position. The first embedded intelligent control device calibrates the position and attitude of the second unmanned underwater vehicle 200 based on this distance to ensure the correct position and attitude of the second unmanned underwater vehicle 200, thereby ensuring the accuracy of the relay subsystem's calibration of the position and attitude of the first unmanned underwater vehicle 100.

[0110] Based on the above embodiments, magnetic field measurements typically require the magnetic measuring instrument to reach a certain depth before measurements can be performed. Underwater depth significantly affects underwater magnetic field measurements. Water currents at different depths not only suppress high-frequency information from changing geomagnetic fields, but the activity of these changing geomagnetic fields also influences the characteristics of the induced geomagnetic field. Therefore, the first unmanned submersible 100 and the second unmanned submersible 200 of this application can only begin the magnetic field measurement process after descending to a certain underwater depth.

[0111] According to one embodiment of this application, the process of the first unmanned submersible 100 and the second unmanned submersible 200 descending to a certain underwater depth will be described and explained below.

[0112] The measurement subsystem is also equipped with a first depth sensor. The function of the first depth sensor is to detect the water depth at the current position of the first unmanned submersible 100 and obtain the water depth at the location of the first unmanned submersible 100.

[0113] In this specific embodiment, this application uses a depth sensor to detect the water depth at the current position of the first unmanned submersible 100. When the water depth at its current position has not reached the designated underwater depth, the first unmanned submersible 100 continues to move vertically downwards. When the water depth at its current position reaches the designated underwater depth, the first unmanned submersible 100 stops moving and remains stationary, ensuring that the first unmanned submersible 100 reaches the depth for underwater magnetic field measurement, thus providing a guarantee for high-precision magnetic field measurement.

[0114] The relay subsystem is also equipped with a second depth sensor. The function of the second depth sensor is to detect the water depth at the current location of the second unmanned submersible 200 and obtain the water depth at the location of the second unmanned submersible 200.

[0115] In this specific embodiment, the second unmanned underwater vehicle 200, equipped with a relay subsystem, serves as the basis for calibrating the first unmanned underwater vehicle 100. Therefore, the underwater depth reached by the second unmanned underwater vehicle 200 affects the accuracy of the relay subsystem's position and attitude calibration of the first unmanned underwater vehicle 100 to a certain extent. This application uses a depth sensor to detect the water depth at the current position of the second unmanned underwater vehicle 200. When the water depth at its current position has not reached the designated underwater depth, the second unmanned underwater vehicle 200 maintains vertical downward movement. When the water depth at its current position reaches the designated underwater depth, the second unmanned underwater vehicle 200 stops moving and remains stationary, ensuring that the second unmanned underwater vehicle 200 reaches the depth for underwater magnetic field measurement and improving the accuracy of magnetic field measurement.

[0116] In one embodiment of this application, the first embedded intelligent control device and the second embedded intelligent control device are also used to generate specific state information of the unmanned underwater vehicle.

[0117] Specifically, the first embedded intelligent control device also includes generating specific state information of the first unmanned underwater vehicle 100. Optionally, the specific state information of the first unmanned underwater vehicle 100 includes at least the motion state of the first unmanned underwater vehicle 100, the position information of the magnetic field measurement position it has reached, and the first attitude calibration signal. The specific state information of the first unmanned underwater vehicle 100 is transmitted to the relay subsystem through the first optical fiber communication device and the second optical fiber communication device.

[0118] Specifically, the second embedded intelligent control device also includes generating specific state information of the second unmanned underwater vehicle 200. Optionally, the specific state information of the second unmanned underwater vehicle 200 includes at least the motion state of the second unmanned underwater vehicle 200, the position information of the magnetic field measurement position it has reached, and the second pose calibration signal.

[0119] An embodiment of this application will be further described and illustrated below, illustrating the control subsystem. This control subsystem includes: a radio communication device and a host computer.

[0120] It should be noted that radio communication equipment is a device on ships that uses radio waves to transmit information. Its primary purpose is for external communication and it is the only means of long-distance communication. A radio communication device consists of a transmitter, receiver, antenna, feeder, and corresponding terminal equipment.

[0121] In this specific embodiment, the radio communication device and the buoy communication device 500 transmit magnetic field measurement information, specific information of the first unmanned underwater vehicle 100, and specific information of the second unmanned underwater vehicle 200, thereby realizing communication between the control subsystem and the relay subsystem. The host computer processes the magnetic field measurement information, the specific information of the first unmanned underwater vehicle 100, and the specific information of the second unmanned underwater vehicle 200, and analyzes the underwater magnetic field situation. The host computer displays the processed results on the human-computer interaction interface, showing the user important information such as the current status information of the unmanned underwater vehicle, the underwater magnetic field information, and the movement trajectory of the unmanned underwater vehicle.

[0122] Based on the current characteristics of underwater magnetic field measurement, this invention utilizes a swarm intelligence algorithm to achieve autonomous and efficient underwater magnetic field detection through the collaborative efforts of multiple unmanned submersibles. Simultaneously, this invention employs a cooperative positioning method to ensure the accuracy of positioning for both the unmanned submersible and the magnetic field measurement device, as well as the accuracy of underwater magnetic field measurements, ensuring real-time communication and the observability of the entire underwater operation process.

[0123] Reference Figure 4 As shown, Figure 4 The diagram shows a flowchart of a high-precision underwater magnetic field measurement method provided in an embodiment of this application. In conjunction with the preceding description of the high-precision underwater magnetic field measurement system, an embodiment of this application will be described and explained below. This high-precision underwater magnetic field measurement method may include, but is not limited to, the following steps.

[0124] 101. The second UUV remains stationary, while the first UUV navigates towards the i-th magnetic field measurement position. The underwater measurement subsystem transmits a second high-frequency sonar signal. The underwater relay subsystem uses the transmission and arrival times of the second high-frequency sonar signal to perform attitude calibration on the first UUV, ensuring that the first UUV can reach the i-th magnetic field measurement position. Where i = 1, 2, 3, ..., n.

[0125] It should be noted that the magnetic field measurement trajectory of this application is arranged with i magnetic field measurement positions and corresponding magnetic field measurement sub-positions. The number of magnetic field measurement sub-positions is the same as the number of magnetic field measurement positions. Wherein, i = 1, 2, 3, ..., n. This application does not impose a specific limit on the number of magnetic field measurement positions.

[0126] It should be noted that when the first unmanned underwater vehicle 100 reaches the i-th magnetic field measurement position, it stops sailing, and the second unmanned underwater vehicle 200 moves along the trajectory towards the corresponding magnetic field measurement sub-position. When the second unmanned underwater vehicle 200 reaches the corresponding magnetic field measurement sub-position, it stops sailing, and the first unmanned underwater vehicle 100 moves along the trajectory towards the next magnetic field measurement position. This cycle continues until the second unmanned underwater vehicle 200 reaches the last magnetic field measurement sub-position, at which point the first unmanned underwater vehicle 100 and the second unmanned underwater vehicle 200 return to the starting position of the trajectory.

[0127] In this step, the first unmanned underwater vehicle 100 carrying the magnetic measurement instrument needs to first reach its magnetic field measurement location, i.e., the i-th magnetic field measurement location. To prevent the first unmanned underwater vehicle 100 from veering off course during its journey to the magnetic field measurement location, its high-frequency sonar transducer array 110 continuously emits high-frequency sonar signals during its journey. The relay subsystem receives these high-frequency sonar signals and uses them to calibrate the position and attitude of the first unmanned underwater vehicle 100 in real time. This prevents the first unmanned underwater vehicle 100 from deviating from the magnetic field measurement route, ensuring that the first unmanned underwater vehicle 100 accurately reaches the magnetic field measurement location, thereby ensuring the accuracy of the underwater magnetic field measurement.

[0128] In this application, since the first unmanned underwater vehicle 100 carries the measurement subsystem, its position and attitude significantly affect the accuracy of the magnetic field measurement. If the position and attitude of the first unmanned underwater vehicle 100 are incorrect, it will prevent it from accurately reaching the magnetic field measurement location, or cause errors in the angle at which the magnetic field measurement instrument it carries measures the magnetic field. Therefore, calibrating the position and attitude of the first unmanned underwater vehicle 100 is essential. To reduce the impact of the position and attitude of the first unmanned underwater vehicle 100 on the magnetic field measurement, ensure that the first unmanned underwater vehicle 100 maintains the correct position and attitude, and ensure that it accurately reaches the magnetic field measurement location, this application controls the high-frequency sonar transducer group 110 to continuously emit high-frequency sonar signals. The relay subsystem receives these high-frequency sonar signals and continuously calibrates the position and attitude of the first unmanned underwater vehicle 100 based on these signals, ensuring that the first unmanned underwater vehicle 100 reaches the magnetic field measurement location.

[0129] 102. When the first UUV reaches the i-th magnetic field measurement position, the first UUV stops sailing, and the underwater measurement subsystem measures the underwater magnetic field and outputs the magnetic field measurement information to the underwater relay subsystem. Where i = 1, 2, 3, ..., n.

[0130] In this step, when the first unmanned underwater vehicle 100 accurately arrives at the magnetic field measurement position, the magnetic field measurement device 120 of the measurement subsystem completes the monitoring and data measurement of the underwater magnetic field at the i-th magnetic field measurement position. Afterwards, the measurement subsystem transmits the magnetic field measurement information to the relay subsystem via the first optical fiber communication device.

[0131] 103. When the first UUV reaches the i-th magnetic field measurement position, the second UUV sails to the i-th magnetic field measurement sub-position. During the sailing of the second UUV, the underwater measurement subsystem performs attitude calibration on the second UUV based on the transmission and arrival time of the second high-frequency sonar signal.

[0132] In this step, when the first unmanned underwater vehicle (UUV) 100 arrives at the magnetic field measurement position, it stops moving, while the second UUV 200 begins to move towards the magnetic field measurement position. The purpose of this is to shorten the distance between the second UUV 200 and the first UUV 100, i.e., to shorten the distance between the relay subsystem and the first UUV 100, thereby reducing the positioning and calibration errors of the first UUV 100. During the movement of the second UUV 200, the measurement subsystem calibrates its position and attitude.

[0133] In this application, the position and attitude of the first unmanned underwater vehicle (UUV) 100 are calibrated using the second UUV 200. Therefore, the position and attitude of the second UUV 200 have a certain influence on the attitude calibration of the first UUV 100. If there is a deviation in the position and attitude of the second UUV 200, it may lead to calibration errors when calibrating the position and attitude of the first UUV 100, which in turn may cause measurement errors when the magnetic measuring instrument measures the underwater magnetic field. Therefore, calibrating the position and attitude of the second UUV 200 is also very necessary. To reduce the influence of the position and attitude of the second UUV 200 on the attitude calibration of the first UUV 100, this step controls the high-frequency sonar transducer group 110 to continuously emit high-frequency sonar signals. Based on these high-frequency sonar signals, the measurement subsystem calibrates the position and attitude of the second UUV 200.

[0134] 104. Determine whether the underwater measurement subsystem has completed magnetic field measurements at all magnetic field measurement locations; if not, proceed to step 105.

[0135] 105. Let i = i + 1, and repeat steps 101 to 104.

[0136] If the underwater measurement subsystem completes the magnetic field measurements at all magnetic field measurement locations, then both the first UUV and the second UUV will return to the starting position of the magnetic field measurement trajectory.

[0137] Furthermore, in the above steps, the first unmanned underwater vehicle 100 sends magnetic field measurement information to the second unmanned underwater vehicle 200. When the second unmanned underwater vehicle 200 receives the magnetic field measurement information sent by the first unmanned underwater vehicle 100, the underwater relay subsystem sends the magnetic field measurement information to the central control subsystem. The central control subsystem processes and calculates the magnetic field measurement information, obtains the calculation results, and displays them.

[0138] In one embodiment of this application, the underwater relay subsystem transmits magnetic field measurement information to the central control subsystem. The central control subsystem processes and calculates the magnetic field measurement information, outputs and displays the calculation results, including:

[0139] The underwater relay subsystem acquires magnetic field measurement information through its included second optical fiber communication device;

[0140] The underwater relay subsystem outputs magnetic field measurement information to the central control subsystem through its included buoy communication device;

[0141] The central control subsystem acquires magnetic field measurement information through its included radio communication device, calculates the magnetic field measurement information through its included host computer, outputs the calculation results and displays them.

[0142] In the above steps, the radio receiving device of the central control subsystem receives the information sent by the relay unmanned underwater vehicle platform and inputs the information into the host computer for processing. The host computer displays the processed results on the human-machine interface, showing the user important information such as the current status information of the unmanned underwater vehicle, underwater magnetic field information, and the movement trajectory of the unmanned underwater vehicle.

[0143] In one embodiment of this application, the underwater measurement subsystem in step 101 transmits a second high-frequency sonar signal. The process of transmitting the second high-frequency sonar signal may include, but is not limited to, the following steps.

[0144] 1011, the underwater measurement subsystem transmits a second high-frequency sonar signal through its first and second high-frequency sonar transducers.

[0145] It should be noted that the first high-frequency sonar transducer 111 and the second high-frequency sonar transducer 112 together constitute the high-frequency sonar transducer group 110. The function of the high-frequency sonar transducer group 110 is to emit high-frequency sonar signals, and the signal emitted by the high-frequency sonar transducer group 110 is denoted as the second high-frequency sonar signal.

[0146] Furthermore, the two high-frequency sonar transducers are rigidly connected together and fixed to the first UUV. The first high-frequency sonar transducer 111 is fixed to one end of the first UUV, and the second high-frequency sonar transducer 112 is fixed to the other end.

[0147] In this step, as the first unmanned underwater vehicle 100 moves along the magnetic field measurement trajectory, the high-frequency sonar transducer group 110 continuously emits high-frequency sonar signals until the magnetic field measurement of the entire measurement trajectory is completed. The high-frequency sonar signals emitted by the high-frequency sonar transducer group 110 are provided to the relay subsystem for calibrating the position and attitude of the first unmanned underwater vehicle 100.

[0148] In one embodiment of this application, the underwater relay subsystem in step 101 performs attitude calibration on the first unmanned underwater vehicle 100 based on the second high-frequency sonar signal. The process of performing attitude calibration on the first unmanned underwater vehicle 100 may include, but is not limited to, the following steps.

[0149] 1012, the underwater relay subsystem acquires a second high-frequency sonar signal through its included hydrophone array;

[0150] 1013, the underwater relay subsystem acquires the first transmission time value sent by the underwater measurement subsystem through its included second optical fiber communication device.

[0151] It should be noted that the first launch time value is defined as the time value at which the high-frequency sonar transducer group 110 of the measurement subsystem launches the second high-frequency sonar signal during the navigation of the first unmanned underwater vehicle 100.

[0152] 1023, the underwater relay subsystem records the first arrival time value through its included second embedded intelligent control device.

[0153] It should be noted that the first arrival time value is defined as the time when the second high-frequency sonar signal arrives at the underwater relay subsystem during the navigation of the first unmanned underwater vehicle 100.

[0154] 1024, The second embedded intelligent control device calculates the distance between the first UUV and the i-th magnetic field measurement position by subtracting the first arrival time value and the first transmission time value, and records it as the first distance;

[0155] 1025. Based on the first distance, the second embedded intelligent control device outputs the first posture calibration signal through the second optical fiber communication device.

[0156] It should be noted that the first attitude calibration signal is used to perform attitude calibration on the first unmanned underwater vehicle 100.

[0157] In the above steps, during the navigation of the first unmanned underwater vehicle 100 towards the magnetic field measurement location, the hydrophone array 210 acquires the second high-frequency sonar signal emitted by the high-frequency sonar transducer group 110 of the measurement subsystem in real time. The second embedded intelligent control device records the first arrival time value of the second high-frequency sonar signal to the hydrophone array 210, and acquires the first transmission time value of the second high-frequency sonar signal emitted by the high-frequency sonar transducer group 110 through the second fiber optic communication device. The second embedded intelligent control device processes and calculates the first arrival time value and the first transmission time value to obtain the current position information of the first unmanned underwater vehicle 100, that is, the distance between the first unmanned underwater vehicle 100 and the magnetic field measurement location. Then, the second embedded intelligent control device calibrates the position and attitude of the first unmanned underwater vehicle 100 according to the distance between the first unmanned underwater vehicle 100 and the magnetic field measurement location to ensure that the position and attitude of the first unmanned underwater vehicle 100 are correct, to ensure that the first unmanned underwater vehicle can accurately reach the magnetic field measurement location, and thus ensure the accuracy of underwater magnetic field measurement.

[0158] In one embodiment of this application, the underwater measurement subsystem in step 102 measures the underwater magnetic field and outputs the magnetic field measurement information to the underwater relay subsystem, which may include, but is not limited to, the following steps.

[0159] 1021, the underwater measurement subsystem measures the underwater magnetic field through its included magnetic field measurement device to obtain magnetic field measurement information.

[0160] It should be noted that the magnetic field measuring device 120, also known as a magnetic measuring instrument, is used to measure the underwater magnetic field and obtain magnetic field measurement information. This application does not specifically limit the type of magnetic measuring instrument; its type can be selected according to the actual situation. Therefore, this application also does not specifically limit the physical quantities representing the magnetic field characteristics indicated by the obtained magnetic field measurement information; the physical quantities representing the magnetic field characteristics depend on the type of magnetic measuring instrument.

[0161] 1022, the underwater measurement subsystem transmits magnetic field measurement information to the underwater relay subsystem through its included first optical fiber communication device.

[0162] In the above steps, when the first unmanned underwater vehicle 100 moves along the trajectory to the magnetic field measurement position, the magnetic field measurement device 120 begins to measure the underwater magnetic field information and obtains the magnetic field measurement information; when the second unmanned underwater vehicle 200 moves along the trajectory to the magnetic field measurement sub-position, the magnetic field measurement device 120 stops measuring the underwater magnetic field information. Since the first unmanned underwater vehicle 100 and the second unmanned underwater vehicle 200 are connected via optical fiber 400, i.e., they communicate via optical fiber, the measurement subsystem transmits the magnetic field measurement information to the relay subsystem in real time through the first optical fiber communication device. Optical fiber communication has a wide bandwidth and large communication capacity, capable of supporting the transmission of large amounts of data between the two unmanned underwater vehicles. Furthermore, optical fiber communication is resistant to electromagnetic interference and will not be affected by the underwater magnetic field during communication between the two unmanned underwater vehicles.

[0163] In one embodiment of this application, the underwater measurement subsystem in step 103 performs attitude calibration on the second unmanned underwater vehicle 200 based on the second high-frequency sonar signal. The process of performing attitude calibration on the second unmanned underwater vehicle 200 may include, but is not limited to, the following steps.

[0164] 1031, the underwater measurement subsystem records the second launch time value through its included first embedded intelligent control device.

[0165] It should be noted that the second launch time value is defined as the time value during which the high-frequency sonar transducer group 110 launches the second high-frequency sonar signal during the navigation of the second unmanned underwater vehicle 200.

[0166] 1032, the underwater measurement subsystem acquires the second arrival time value transmitted by the underwater relay subsystem through its included first optical fiber communication device.

[0167] It should be noted that the second arrival time value is defined as the time when the second high-frequency sonar signal arrives at the underwater relay subsystem during the navigation of the second unmanned underwater vehicle 200.

[0168] 1033, the first embedded intelligent control device calculates the distance between the second UUV and the position of the i-th magnetic field measuring sub-sub ...

[0169] 1034. According to the second distance, the first embedded intelligent control device outputs a second pose calibration signal through the first optical fiber communication device. The second pose calibration signal is used to perform pose calibration on the second UUV.

[0170] In this application, during the navigation of the second unmanned underwater vehicle 200 towards the first unmanned underwater vehicle 100, the measurement subsystem calibrates the position and attitude of the second unmanned underwater vehicle 200. The calibration of the position and attitude of the first unmanned underwater vehicle 100 is based on the calibration of the position and attitude of the second unmanned underwater vehicle 200. The position and attitude of the second unmanned underwater vehicle 200 will affect the received second high-frequency sonar signal, potentially causing errors in the received signal. This, in turn, leads to erroneous calibration of the attitude and position of the first unmanned underwater vehicle 100 by the relay subsystem. Therefore, it is necessary for the relay subsystem to calibrate the position and attitude of the second unmanned underwater vehicle 200 simultaneously with the calibration of the position and attitude of the first unmanned underwater vehicle 100.

[0171] The hydrophone array 210 of the relay subsystem acquires the second high-frequency sonar signal emitted by the high-frequency sonar transducer group 110 of the measurement subsystem in real time. The first embedded intelligent control device transmits the arrival time value of the acquired second high-frequency sonar signal at the hydrophone array 210, i.e., the second arrival time value, through the second optical fiber communication device. The first embedded intelligent control device calculates the difference between the second arrival time value and the second transmission time value to obtain the current position information of the second unmanned underwater vehicle 200, i.e., the distance between the second unmanned underwater vehicle 200 and the magnetic field measuring sub-position. The first embedded intelligent control device calibrates the position and attitude of the second unmanned underwater vehicle 200 based on this distance to ensure that the position and attitude of the second unmanned underwater vehicle 200 are correct, thereby ensuring the accuracy of the position and attitude calibration of the first unmanned underwater vehicle 100 by the relay subsystem.

[0172] In another embodiment of this application, the entity performing the calibration of the position and attitude of the second unmanned underwater vehicle 200 can also be a second embedded intelligent control device, and the measurement subsystem may not need to include a first embedded intelligent control device. Specifically, the second embedded intelligent control device acquires a second launch time value and records a second arrival time value, calculates the difference between the second arrival time value and the second launch time value to obtain the current position information of the second unmanned underwater vehicle 200, i.e., the distance between the second unmanned underwater vehicle 200 and the magnetic field measuring sub-position. The second embedded intelligent control device calibrates the position and attitude of the second unmanned underwater vehicle 200 based on this distance.

[0173] In one embodiment of this application, prior to step 101, the following is further included:

[0174] A. The first UUV and the second UUV descend to the designated underwater depth, and the first UUV and the second UUV are located at the starting point of the magnetic field measurement trajectory.

[0175] Furthermore, step A may include, but is not limited to, the following steps:

[0176] A1, during the descent of the first UUV in the water, the underwater measurement subsystem measures the water depth at the location of the first UUV using its included first depth sensor. When the water depth at the location of the first UUV is the specified underwater depth, the first UUV stops descent.

[0177] In this step, magnetic field measurement typically requires the magnetic measuring instrument to reach a certain depth before measurement can be performed. Underwater depth significantly affects the measurement of the underwater magnetic field. Water currents at different depths not only suppress high-frequency information from changing geomagnetic fields, but the activity of these changing geomagnetic fields also influences the characteristics of the induced geomagnetic field. This application uses a depth sensor to detect the water depth at the current position of the first unmanned underwater vehicle 100. When the water depth at its current position has not reached the designated underwater depth, the first unmanned underwater vehicle 100 continues to move vertically downwards. When the water depth at its current position reaches the designated underwater depth, the first unmanned underwater vehicle 100 stops moving and remains stationary, ensuring that the first unmanned underwater vehicle 100 reaches the depth required for underwater magnetic field measurement and improving the accuracy of the magnetic field measurement.

[0178] A2, during the descent of the second UUV in the water, the underwater relay subsystem measures the water depth at the location of the second UUV using its included second depth sensor. When the water depth at the location of the second UUV is the specified underwater depth, the second UUV stops descent.

[0179] In this step, the second unmanned underwater vehicle 200, equipped with a relay subsystem, serves as the basis for calibrating the first unmanned underwater vehicle 100. Therefore, the underwater depth reached by the second unmanned underwater vehicle 200 affects the accuracy of the relay subsystem's position and attitude calibration of the first unmanned underwater vehicle 100 to a certain extent. This application uses a depth sensor to detect the water depth at the current position of the second unmanned underwater vehicle 200. When the water depth at its current position has not reached the designated underwater depth, the second unmanned underwater vehicle 200 maintains vertical downward movement. When the water depth at its current position reaches the designated underwater depth, the second unmanned underwater vehicle 200 stops moving and remains stationary, ensuring that the second unmanned underwater vehicle 200 reaches the depth for underwater magnetic field measurement and improving the accuracy of magnetic field measurement.

[0180] In one embodiment of this application, prior to step A, the following is further included:

[0181] Step 1: One end of the first rigid telescopic rod 310 of the base station positioning subsystem 300 is fixed to the bow of the ship, and the other end of the first rigid telescopic rod 310 is connected to a high-frequency sonar beam emitter 320.

[0182] It should be noted that the vessel refers to the vessel used by the user of this high-precision underwater magnetic field measurement system.

[0183] Step 2: The high-frequency sonar spotlight transmitter 320, the first UUV and the second UUV are placed underwater, and the high-frequency sonar spotlight transmitter 320 emits the first high-frequency sonar signal vertically downward.

[0184] Step 3: The underwater relay subsystem acquires the first high-frequency sonar signal through its included hydrophone array 210;

[0185] Step four: The underwater relay subsystem, through its included second embedded intelligent control device, adjusts the pose of the second UUV in conjunction with the first high-frequency sonar signal to ensure that the initial position of the second UUV is directly below the high-frequency sonar beam emitter 320.

[0186] It should be noted that ensuring the initial position of the second UUV is directly below the high-frequency sonar beam emitter 320 is to ensure that the second unmanned underwater vehicle 200 is at the starting position of the magnetic field measurement trajectory.

[0187] In the above steps, the high-frequency sonar beamforming transmitter 320 emits high-frequency sonar signals downwards in a vertical direction and aggregates the sonar signals for easy reception by the relay subsystem. The hydrophone array 210 of the relay subsystem receives the first high-frequency sonar signal, and the three hydrophones in the array 210 are arranged in an equilateral triangle. The relay subsystem corrects the position and attitude of the second unmanned underwater vehicle 200 based on the first high-frequency sonar signal. When the distance between the three hydrophones is equal, it indicates that the second unmanned underwater vehicle 200 is directly below the high-frequency sonar beamforming transmitter 320.

[0188] Optionally, the underwater relay subsystem, through its included second embedded intelligent control device, adjusts the pose of the second UUV in conjunction with the first high-frequency sonar signal to ensure that the second UUV is directly below the high-frequency sonar beam emitter 320, specifically including:

[0189] Step 41: The second embedded intelligent control device acquires the third arrival time value.

[0190] It should be noted that the third arrival time value is the time when the first high-frequency sonar signal arrives at the hydrophone array 210 of the underwater relay subsystem during the process of the second unmanned submersible 200 descending to a certain depth.

[0191] Step 42: The buoy communication device acquires the third transmission time value and forwards it to the second embedded intelligent control device.

[0192] It should be noted that the third launch time value is the time value at which the high-frequency sonar spotter 320 launches the first high-frequency sonar signal during the process of the second unmanned submersible 200 descending to a certain depth.

[0193] Step 43: The second embedded intelligent control device calculates the difference between the third arrival time value and the third transmission time value, and records it as the third distance;

[0194] Step 44: Based on the third distance, the second embedded intelligent control device adjusts the pose of the second UUV to ensure that the second UUV is directly below the high-frequency sonar beam emitter.

[0195] Reference Figures 5A to 5C As shown, Figure 5A The diagram shown is a schematic diagram of the first application scenario of the high-precision underwater magnetic field measurement method provided in the embodiments of this application; Figure 5B The diagram shown is a second application scenario of the high-precision underwater magnetic field measurement method provided in this application embodiment; Figure 5C The diagram shown illustrates a third application scenario of the high-precision underwater magnetic field measurement method provided in this application. The working process and principle of the high-precision underwater magnetic field measurement method provided in this application will be explained and illustrated below with an example. Figures 5A to 5C The circles with shaded areas represent the magnetic field measurement positions and sub-positions, respectively, while the dashed lines represent the magnetic field measurement trajectory.

[0196] Assume there are four magnetic field measurement positions and four corresponding sub-positions along the magnetic field measurement trajectory. Before conducting the magnetic field measurement, the following setup is performed: The user travels by boat to a designated location for the measurement. The user must install the first rigid telescopic rod 310 at the bow of the boat, securing one end of the rod to the bow with a rope. The other end of the rod is equipped with a high-frequency sonar beam emitter 320. Afterward, the user must submerge the first unmanned underwater vehicle 100, the second unmanned underwater vehicle 200, and the high-frequency sonar beam emitter 320 underwater.

[0197] After the first unmanned underwater vehicle 100, the second unmanned underwater vehicle 200, and the high-frequency sonar spotlight transmitter 320 are all deployed underwater, the first unmanned underwater vehicle 100 and the second unmanned underwater vehicle 200 reach the designated underwater depth through their deployed depth sensors. Simultaneously, the high-frequency sonar spotlight transmitter 320 emits a first high-frequency sonar signal to allow the second unmanned underwater vehicle 200 to adjust its position and attitude, ensuring that it is directly below the high-frequency sonar spotlight transmitter 320. The status of the two unmanned underwater vehicles is as follows: Figure 5A As shown.

[0198] Once both unmanned submersibles (UUVs) have reached the designated underwater depth, and the second UUV 200 is directly below the high-frequency sonar beam emitter 320, the first UUV 100 begins to move towards the first magnetic field measurement location, while the second UUV 200 remains stationary. During the movement of the first UUV 100 towards the first magnetic field measurement location, the high-frequency sonar transducer array 110 continuously transmits a second high-frequency sonar signal. The relay subsystem calibrates the position and attitude of the first UUV 100 based on the second high-frequency sonar signal, ensuring that the first UUV 100 accurately reaches the first magnetic field measurement location.

[0199] When the first unmanned submersible 100 accurately reaches the first magnetic field measurement location, the first unmanned submersible 100 stops moving and controls the magnetic field measurement device 120 to detect the underwater magnetic field at that location. At this time, the status of the two unmanned submersibles is as follows: Figure 5B As shown. Simultaneously, the second unmanned underwater vehicle 200 moves towards the first magnetic field measurement sub-position, and the measurement subsystem corrects the position and attitude of the second unmanned underwater vehicle 200 based on the second high-frequency sonar signal. When the second unmanned underwater vehicle 200 reaches the first magnetic field measurement sub-position, it stops moving. At this time, the states of the two unmanned underwater vehicles are as follows. Figure 5C As shown. Afterwards, the first unmanned underwater vehicle 100 began to move towards the second magnetic field measurement position. During the movement of the first unmanned underwater vehicle 100 towards the second magnetic field measurement position, the high-frequency sonar transducer assembly 110 continued to transmit the second high-frequency sonar signal. The status of the two unmanned underwater vehicles is as follows. Figure 5A As shown, the relay subsystem calibrates the position and attitude of the first unmanned underwater vehicle 100 based on the second high-frequency sonar signal, enabling the first unmanned underwater vehicle 100 to accurately reach the second magnetic field measurement position.

[0200] When the first unmanned submersible 100 reaches the second magnetic field measurement position, the first unmanned submersible 100 stops moving and controls the magnetic field measurement device 120 to detect the underwater magnetic field at that position. At this time, the status of the two unmanned submersibles is as follows: Figure 5B As shown. Simultaneously, the second unmanned underwater vehicle 200 moves towards the second magnetic field measurement sub-position, and the relay subsystem corrects the position and attitude of the second unmanned underwater vehicle 200 based on the second high-frequency sonar signal. When the second unmanned underwater vehicle 200 reaches the second magnetic field measurement sub-position, it stops moving. At this time, the states of the two unmanned underwater vehicles are as follows. Figure 5C As shown. Afterwards, the first unmanned underwater vehicle 100 began moving towards the third magnetic field measurement position. During the movement of the first unmanned underwater vehicle 100 towards the third magnetic field measurement position, the high-frequency sonar transducer assembly 110 continued to transmit the second high-frequency sonar signal. The status of the two unmanned underwater vehicles is as follows. Figure 5AAs shown, the relay subsystem calibrates the position and attitude of the first unmanned underwater vehicle 100 based on the second high-frequency sonar signal, enabling the first unmanned underwater vehicle 100 to accurately reach the third magnetic field measurement location.

[0201] When the first unmanned submersible 100 reaches the third magnetic field measurement position, the first unmanned submersible 100 stops moving and controls the magnetic field measurement device 120 to detect the underwater magnetic field at that position. At this time, the status of the two unmanned submersibles is as follows: Figure 5B As shown. Simultaneously, the second unmanned underwater vehicle 200 moves towards the third magnetic field measurement sub-position, and the relay subsystem corrects the position and attitude of the second unmanned underwater vehicle 200 based on the second high-frequency sonar signal. When the second unmanned underwater vehicle 200 reaches the third magnetic field measurement sub-position, it stops moving. At this time, the states of the two unmanned underwater vehicles are as follows. Figure 5C As shown. The first unmanned underwater vehicle 100 begins to move towards the fourth magnetic field measurement position. During the movement of the first unmanned underwater vehicle 100 towards the fourth magnetic field measurement position, the high-frequency sonar transducer assembly 110 continues to transmit the second high-frequency sonar signal. The status of the two unmanned underwater vehicles is as follows. Figure 5A As shown, the relay subsystem calibrates the position and attitude of the first unmanned underwater vehicle 100 based on the second high-frequency sonar signal, enabling the first unmanned underwater vehicle 100 to accurately reach the fourth magnetic field measurement location.

[0202] When the first unmanned submersible 100 reaches the fourth magnetic field measurement location, it stops moving and controls the magnetic field measurement device 120 to detect the underwater magnetic field at that location. At this time, the status of the two unmanned submersibles is as follows: Figure 5B As shown. Simultaneously, the second unmanned underwater vehicle 200 moves towards the fourth magnetic field measurement sub-position, and the relay subsystem corrects the position and attitude of the second unmanned underwater vehicle 200 based on the second high-frequency sonar signal. When the second unmanned underwater vehicle 200 reaches the fourth magnetic field measurement sub-position, both the first unmanned underwater vehicle 100 and the second unmanned underwater vehicle 200 return to the starting position of their trajectory. At this point, the underwater magnetic field measurement is complete.

[0203] The magnetic field measurement information obtained at these four locations is transmitted in real time to the central control subsystem via the buoy communication device 500. The radio receiving device receives the information relayed by the unmanned submersible platform and inputs it into the host computer for processing. The host computer then displays the processed results on the human-machine interface, showing the user important information such as the current status of the unmanned submersible, underwater magnetic field information, and the unmanned submersible's trajectory.

[0204] The technical benefits of the high-precision underwater magnetic field measurement method and system provided in this application include at least one of the following:

[0205] (1) It is easy to operate and has good mobility, which reduces the cost of magnetic field measurement.

[0206] The system described in this application can autonomously and efficiently measure underwater magnetic fields using only two unmanned underwater vehicles (UUVs), without the need for human control or the construction of a fixed underwater magnetic field measurement site. Furthermore, the system is small in size, easy to carry, and can conveniently perform magnetic field measurement operations during long voyages.

[0207] (2) It can improve the accuracy and efficiency of magnetic field measurement.

[0208] This application employs two sets of unmanned underwater vehicles (UUVs) to collaboratively measure the magnetic field in different areas. The second UUV 200 calibrates the attitude of the first UUV 100, which carries the measurement subsystem, reducing accumulated positioning errors and improving both positioning accuracy and work efficiency. Specifically, this application uses an underwater relay subsystem to autonomously and accurately acquire the position and attitude information of the first UUV 100 and calibrate its position and attitude, achieving high-precision underwater positioning of the first UUV 100 and ensuring that its position and attitude are within the correct range. Furthermore, the underwater measurement subsystem acquires the position and attitude information of the second UUV 200 and calibrates its position and attitude. This ensures that the attitude and position of the second UUV 200 are also correct, improving the accuracy of the relay subsystem's calibration of the first UUV 100's attitude and reducing calibration errors.

[0209] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatuses.

[0210] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items.

[0211] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, apparatuses, or units, and may be electrical, mechanical, or other forms.

[0212] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, the functional units in the various embodiments of this application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The integrated units described above can be implemented in hardware or as software functional units.

[0213] The step numbers in the above method embodiments are set only for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

Claims

1. A high-precision underwater magnetic field measurement method, applied to an underwater magnetic field high-precision measurement system, the system comprising: A first UUV and a second UUV are connected by an optical fiber. Both the first UUV and the second UUV travel along a magnetic field measurement trajectory. The magnetic field measurement trajectory is set with i magnetic field measurement positions and i corresponding magnetic field measurement sub-positions, where i = 1, 2, 3, ..., b. The underwater measurement subsystem is mounted on the first UUV and communicates in real time with the underwater relay subsystem. The underwater relay subsystem is mounted on the second UUV; The central control subsystem communicates in real time with the underwater relay subsystem. Its features include the following steps: The second UUV remains stationary, while the first UUV navigates toward the i-th magnetic field measurement position. The underwater measurement subsystem transmits a second high-frequency sonar signal, and the underwater relay subsystem performs attitude calibration on the first UUV based on the transmission and arrival times of the second high-frequency sonar signal to ensure that the first UUV can reach the i-th magnetic field measurement position. When the first UUV reaches the i-th magnetic field measurement position, the first UUV stops sailing, and the underwater measurement subsystem measures the underwater magnetic field and outputs the magnetic field measurement information to the underwater relay subsystem; where i = 1, 2, 3, ..., n; When the first UUV reaches the i-th magnetic field measurement position, the second UUV sails to the i-th magnetic field measurement sub-position. During the sailing of the second UUV, the underwater measurement subsystem performs pose calibration on the second UUV based on the transmission and arrival times of the second high-frequency sonar signal. Determine whether the underwater measurement subsystem has completed magnetic field measurements at all the magnetic field measurement locations; If not, then let i = i + 1 and repeat the above steps; If the underwater measurement subsystem completes magnetic field measurements at all the magnetic field measurement locations, then both the first UUV and the second UUV return to the starting position of the magnetic field measurement trajectory. When the second UUV obtains the magnetic field measurement information, the underwater relay subsystem sends the magnetic field measurement information to the central control subsystem. The central control subsystem processes and calculates the magnetic field measurement information, outputs the calculation results, and displays them.

2. The method for high-precision underwater magnetic field measurement according to claim 1, characterized in that, The underwater relay subsystem performs pose calibration on the first UUV using the second high-frequency sonar signal, specifically including: The underwater relay subsystem acquires the second high-frequency sonar signal through its included hydrophone array; The underwater relay subsystem acquires the first transmission time value sent by the underwater measurement subsystem through its included second optical fiber communication device; Wherein, the first transmission time value is defined as the time value at which the underwater measurement subsystem transmits the second high-frequency sonar signal during the first UUV's navigation; The underwater relay subsystem records the first arrival time value through its included second embedded intelligent control device; Wherein, the first arrival time value is defined as the time value at which the second high-frequency sonar signal arrives at the underwater relay subsystem during the first UUV's voyage; The second embedded intelligent control device calculates the distance between the first UUV and the i-th magnetic field measurement position by subtracting the first arrival time value and the first transmission time value, and records it as the first distance; Based on the first distance, the second embedded intelligent control device outputs a first pose calibration signal through the second optical fiber communication device. The first pose calibration signal is used to perform pose calibration on the first UUV. The hydrophone array includes three hydrophones arranged in an equilateral triangle with the center of the second UUV as the center. Each hydrophone is used to receive the second high-frequency sonar signal.

3. The method for high-precision underwater magnetic field measurement according to claim 1, characterized in that, During the navigation of the second UUV, the underwater measurement subsystem performs attitude calibration on the second UUV based on the second high-frequency sonar signal, specifically including: The underwater measurement subsystem records the second launch time value through its first embedded intelligent control device. The second transmission time value is defined as the time value at which the underwater measurement subsystem transmits the second high-frequency sonar signal during the navigation of the second UUV. The underwater measurement subsystem acquires the second arrival time value sent by the underwater relay subsystem through its first optical fiber communication device; The second arrival time value is defined as the time when the second high-frequency sonar signal arrives at the underwater relay subsystem during the second UUV's navigation. The first embedded intelligent control device calculates the distance between the second UUV and the position of the i-th magnetic field measuring sub-position by subtracting the second arrival time value and the second transmission time value, and records it as the second distance; Based on the second distance, the first embedded intelligent control device outputs a second pose calibration signal through the first optical fiber communication device. The second pose calibration signal is used to perform pose calibration on the second UUV.

4. The underwater magnetic field high-precision measurement method according to claim 1, characterized in that, Before the first UUV travels to the i-th magnetic field measurement position while the second UUV remains stationary, the process further includes: The first UUV and the second UUV descend to a specified underwater depth, and the first UUV and the second UUV are located at the starting position of the magnetic field measurement trajectory; Wherein, the first UUV and the second UUV descend to a specified underwater depth, including: During the descent of the first UUV in the water, the underwater measurement subsystem measures the water depth at the location of the first UUV using its included first depth sensor. When the water depth at the location of the first UUV is the specified underwater depth, the first UUV stops descent. During the descent of the second UUV in the water, the underwater relay subsystem measures the water depth at the location of the second UUV using its included second depth sensor. When the water depth at the location of the second UUV reaches the specified underwater depth, the second UUV stops descent.

5. The underwater magnetic field high-precision measurement method according to claim 4, characterized in that, The system also includes: a base station positioning subsystem; Before the first UUV and the second UUV descend to the designated underwater depth, the process also includes: One end of the first rigid telescopic rod of the base station positioning subsystem is fixed to the bow of the ship, and the other end of the first rigid telescopic rod is connected to a high-frequency sonar beam emitter. The high-frequency sonar spotter, the first UUV, and the second UUV are placed underwater, and the high-frequency sonar spotter emits a first high-frequency sonar signal vertically downwards. The underwater relay subsystem acquires the first high-frequency sonar signal through its included hydrophone array; The underwater relay subsystem, through its included second embedded intelligent control device, combines the first high-frequency sonar signal to adjust the pose of the second UUV, ensuring that the initial position of the second UUV is directly below the high-frequency sonar beam emitter.

6. The method for high-precision underwater magnetic field measurement according to claim 1, characterized in that, The underwater measurement subsystem transmits a second high-frequency sonar signal, including: The underwater measurement subsystem transmits the second high-frequency sonar signal through its first and second high-frequency sonar transducers. The first high-frequency sonar transducer and the second high-frequency sonar transducer are connected by a rigid body. The first high-frequency sonar transducer is fixed to one end of the first UUV, and the second high-frequency sonar transducer is fixed to the other end of the first UUV.

7. The method for high-precision underwater magnetic field measurement according to claim 1, characterized in that, The underwater measurement subsystem measures the underwater magnetic field and outputs the magnetic field measurement information to the underwater relay subsystem, including: The underwater measurement subsystem measures the underwater magnetic field through its included magnetic field measurement device to obtain the magnetic field measurement information. The underwater measurement subsystem transmits the magnetic field measurement information to the underwater relay subsystem via its included first optical fiber communication device.

8. The method for high-precision underwater magnetic field measurement according to claim 1, characterized in that, The underwater relay subsystem transmits the magnetic field measurement information to the central control subsystem. The central control subsystem processes and calculates the magnetic field measurement information, outputs and displays the calculation results, including: The underwater relay subsystem acquires the magnetic field measurement information through its included second optical fiber communication device; The underwater relay subsystem outputs the magnetic field measurement information to the central control subsystem through its included buoy communication device; The central control subsystem acquires the magnetic field measurement information through its included radio communication device, calculates the magnetic field measurement information through its included host computer, outputs the calculation results, and displays them.

9. A high-precision underwater magnetic field measurement system, characterized in that, include: The system includes a base station positioning subsystem, an underwater measurement subsystem, an underwater relay subsystem, and a central control subsystem. The underwater measurement subsystem is mounted on a first UUV, and the underwater relay subsystem is mounted on a second UUV. The underwater relay subsystem communicates in real time with the underwater measurement subsystem and the central control subsystem, respectively. The first UUV and the second UUV are connected by optical fiber, and both the first UUV and the second UUV travel along the magnetic field measurement trajectory; The base station positioning subsystem includes: A high-frequency sonar spotter is used to emit a first high-frequency sonar signal downward in a vertical direction. The first high-frequency sonar signal is used to locate the second UUV and ensure that the initial position of the second UUV is directly below the high-frequency sonar spotter. A rigid telescopic rod, one end of which is fixed to the bow of the ship, and the other end of which is connected to the high-frequency sonar beam emitter; The underwater measurement subsystem includes: The first depth sensor is used to detect the water depth at the location of the first UUV; A magnetic field measuring device is used to measure underwater magnetic fields and obtain magnetic field measurement information. A first high-frequency sonar transducer and a second high-frequency sonar transducer are used to transmit a second high-frequency sonar signal; the first high-frequency sonar transducer and the second high-frequency sonar transducer are connected by a rigid body, the first high-frequency sonar transducer is fixed to one end of the first UUV, and the second high-frequency sonar transducer is fixed to the other end of the first UUV. The first optical fiber communication device is used for real-time communication with the underwater relay subsystem; A first embedded intelligent control device is used to record a second transmission time value and a second arrival time value. Based on the difference between the second transmission time value and the second arrival time value, it outputs a second pose calibration signal to the underwater relay subsystem through the first optical fiber communication device. The second pose calibration signal is used to control the second UUV to perform pose calibration. The first embedded intelligent control device is also used to generate specific state information of the first UUV; The second transmission time value is defined as the time value at which the underwater measurement subsystem transmits the second high-frequency sonar signal during the navigation of the second UUV; The second arrival time value is defined as the time value at which the second high-frequency sonar signal arrives at the underwater relay subsystem during the second UUV's voyage. The underwater relay subsystem includes: The second depth sensor is used to detect the water depth at the location of the second UUV; A hydrophone array comprising three hydrophones arranged in an equilateral triangle with the center of the second UUV as the center, wherein each hydrophone is used to receive the second high-frequency sonar signal. The second optical fiber communication device is used to communicate with the first optical fiber communication device in real time. The second embedded intelligent control device is used to record the first arrival time value and the first transmission time value, and outputs the first pose calibration signal through the second optical fiber communication device based on the difference between the first arrival time value and the first transmission time value. The first pose calibration signal is used to perform pose calibration on the first UUV. Wherein, the first transmission time value is defined as the time value at which the underwater measurement subsystem transmits the second high-frequency sonar signal during the first UUV's navigation; The first arrival time value is defined as the time when the second high-frequency sonar signal arrives at the underwater relay subsystem during the first UUV's voyage. The second embedded intelligent control device is also used to generate specific state information of the second UUV; A buoy communication device is used to output the magnetic field measurement information, the specific status information of the first UUV, and the specific status information of the second UUV to the central control subsystem. The central control subsystem includes: A radio communication device for real-time communication with the buoy communication device; The host computer is used to process the magnetic field measurement information, the specific status information of the first UUV and the specific status information of the second UUV, output the processing results and display them on the human-computer interaction interface.

10. A high-precision underwater magnetic field measurement system according to claim 9, characterized in that, The hydrophone array is also used to acquire the first high-frequency sonar signal; The second embedded intelligent control device is also used to adjust the pose of the second UUV in conjunction with the first high-frequency sonar signal to ensure that the second UUV is directly below the high-frequency sonar beam emitter.

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